Science Lecture: Talking the Higgs Boson with Dr. Joseph Incandela

Uploaded by USdepartmentofenergy on 17.09.2012

bjbj U.S. Department of Energy Science Lecture: Talking the Higgs Boson with Dr. Joseph Incandela
Welcome: William Brinkman, Director of Office of Science, Department of Energy; Secretary
of Energy Steven Chu Speaker: Joseph Incandela, Professor of Physics at the University of
California, Santa Barbara; Spokesperson for the Compact Muon Solenoid Experiment at the
Large Hadron Collider Location: Forrestal Large Auditorium, Department of Energy, Washington,
D.C. Time: 10:00 a.m. EDT Date: Friday, September 14, 2012 Transcript by Federal News Service,
Washington, D.C. WILLIAM BRINKMAN: Good morning. I m Bill Brinkman, I m the director of the
Office of Science, and I d like to thank all of you for joining us at our third science
lecture. These those of you who are here in the auditorium as well as all of you who are
watching online at Germantown, so we hope we have a good audience out there as well
as here. d especially like to welcome our distinguished guest Joe Incandela and Secretary
Steven Chu. You ll hear from Joe and about the and about the Higgs boson in a few moments.
I m proud of the work that he and so many others have, supported by the Office of Science,
did in the long search for this important particle, and there are many contributions
to the potential breakthrough this past summer that s wonderful. Like you, I m looking forward
to hearing more about their efforts, but I d first like to thank Secretary Chu for initiating
this lecture series. This is this is just one of his achievements as the energy secretary,
and I believe that he has accomplished many things in the past three and a half years.
ve brought significant new resources to the innovative approaches to the department s
research and development mission. We re breaking down stovepipes between our existing basic
and applied sciences teams and also launched new research models, like the energy frontier
research centers, the energy innovation hubs and ARPA-E. These activities created a new
and exciting interest in solving the world s energy problems sustainably. Our investments
in wind and solar power have put the country on track to double renewable energy over the
past four years. We ve partnered with utilities, local communities and other federal agencies
to accelerate America s transition to a stronger, smarter, more robust power grid, including
more than 30 smart grid and energy storage demonstration projects nationwide. Steve personally
took responsibility for our response to the Macondo oil spill and the Fukushima nuclear
disaster. In both cases, we managed to bring useful resources to the problems and helped
solve critical issues. Secretary Chu has led all this and more. So it s my pleasure in
to welcome him today as he introduces our speaker for today s science lecture. Please
join us in welcoming Secretary Chu. (Applause.) SECRETARY STEVEN CHU: Thank you. I m going
to my pleasure to introduce our speaker today, Joseph Incandela. I m just going to give you
a brief bio, and then I m going to try to give you a five-minute synopsis of what he
s going a prelude to what he s going to talk about. So Professor Incandela is a professor
of physics at the University of California Santa Barbara. He got his Ph.D. with Henry
Frisch at the University of Chicago in experiment looking for monopoles there was a potential
candidate monopole before a couple of years later that turned out not to be. And he went
into hadron physics, worked at Fermi lab in the 90s, then became professor at Santa Barbara,
started working at CERN, and he rose in the CERN ranks working on the Compact Nuon Solenoid
collaboration which you will hear about, and right now he is been elected the senior spokesman
for that group. So you will hear about what they have been doing at CERN at the Large
Hadron Collider, not only that particular group, but I presume the other (day ?), ATLAS
and others. I see but anyway but let me tell you about what this is so I m going to go
back in time, way back in time, a couple hundred years, and when physics was first essentially
being born in a quantitative way, we began to try to describe forces like gravitational
forces, and the remarkable thing about these forces is, people began to realize that these
forces had a universality to them in the sense that the same force that was responsible for
an apple falling on the Earth would also be responsible for the planets circling the sun
and the dynamics of the galaxies and so on and so forth. or the same forces actually,
with a smaller mass, should be there, indeed, on atomic and quantum scale. So the gravitational
force was something that would be universal over all scales, that goes over many, many
orders of magnitude, all right? Which is something different. Usually in science, you think of
something, ah, it works in this range, and there and it s not going to work everywhere
else. So one of the most successful theories in physics in the later half of the 20th century
was electricity of magnetism, which had its roots first unified by Maxwell around the
time of the Civil War in the 1860s. And in and then there was a realization that electricity
and magnetism were really a unified force, even though they looked very different, and
then, much later, Einstein came along and said, not only do they kind of look the same,
they are the same. They re unified, and you can write a set of equations, but they re
even more unified than you think in the following sense. Suppose you have, let s say, a coordinate
system. An X axis and a Y axis, OK? And in that coordinate system, you might say, where
is my nose along the X axis and the Y axis, right? It s there, and it s got an X coordinate,
Y coordinate. But if you rotate the coordinate system, the coordinates change, the nose is
still there, OK? And Einstein said, to degree there s a magnetic field, an electric field
depends on the relative velocity of an object and the observer. And you by so by going to
different velocity frames, it s like a rotation, and so the amount of the electrical field
and the magnetic field are just like X and Y axes, truly unified, OK? With me so far?
So that rotation was a rotation and transformation of velocity space. Then there were great attempts
by Einstein and others to unify gravity and the electromagnetic forces, and he did not
succeed, others did not succeed. But then in the 60s there came a maybe you can unify
the electric and magnetic forces with weak nuclear forces. These are the forces responsible
for radioactive decay. And what do you mean by unification? You mean exactly the same
thing. You have a set of fields so every force, there s now a field. There s electromagnetic
forces, there s an electromagnetic field. We learn by electrodynamics that with this
field are associate quanta or particles, photons. So you got a field, you got a force, you got
a particle associated with the field. So the unification of the weak and electromagnetic
forces where, OK, there were two fields that we knew about the weak forces in the electromagnetic
field, but in order to unify it, they had to postulate another weak field, one positively-charged,
negatively-charged and one neutral with the electromagnetic, now the four of them and
guess what? If you rotated you first construct this field mathematically, and with very,
very symmetric looking. Then you do a fake rotation to try to get the real fields, the
electromagnetic field, the two charged fields of weak decay, and this new field that had
to be postulated. And in 1978, strong evidence of the new field emerged and the inventors
of the theory got a Nobel Prize for it. Now, here s the problem. You started with these
four fields four forces, but the weak force is very, very short-range only extended to
the kind of the radius of the nucleus. With a very short-range force, we already know,
since the 1930s, that associated with the particle associated with that field had to
be extremely massive, whereas the electromagnetic field, very long-range, massless, photon massless,
goes at the speed of light. So here, we re in a conundrum. The three weak fields had
to be very, very massive, but we knew that the electromagnetic field, no mass. You do
the rotations, it doesn t confer any mass, OK? So Peter Higgs and others developed what
appeared to be a mathematical trick in order to confer mass. So the so-called Higgs mechanism
was a trick which Professor Incandela will talk about. It was not considered something
it was kind of a I was doing my Ph.D. work at the time, actually on this stuff. It was
not considered really it was a mathematical trick. Now, as time wore on, OK, where were
we? Every force, every field every force there was a field. With a field, you quantize the
field so-called quantum field theory. Once you ve quantized the field, you ll expect
a particle to be there. Now these particles had mass, but the Higgs mechanism sent something
different, because it s not the electromagnetic force or the weak force or the strong force,
it s the coupling of any particle to the vacuum that gives it this mass property, OK? So it
s a very different type of particle than all the other particles, like the photons or the
gluon force bosons or any of those others, OK? So that s what makes it a little bit more
special, which makes it a little bit more exciting. It was so the discovery was a capstone
to that, to this theory that had been developed beginning in the 1960s, and here s the deal:
We want there to be a surprise in this thing. If this particle turns out to be the standard
model which he will talk about this is not good news. (Laughter.) It s good news that
we figured something out, but it s not good news because if this theory turns out to be
right, then we have some fundamental problems of where to go next. And let me finish by
one final thing that brings me back to the universal laws of Newton: We know that our
understanding of nature is inherently inconsistent, therefore, at some level, it has to be wrong,
and it can be described very simply. We believe our understanding of nature is derived from
these so-called quantum fields and quantum descriptions and quantum field descriptions
in nature, but we also have another pillar of science, general relativity. As you get
to smaller and smaller distances, there are fluctuations that get larger and larger, and
once you get so small s such a small dimension these quantum fluctuations that we know are
there get bigger and bigger, and they get and fluctuations in fields means fluctuations
in energy, which fluctuations in energy is linked to mass. The fluctuations get so large
that in that dimension and in that space, you go into singularity space in the sense
that you now have black hole type stuff. You have mathematical singularities popping up.
So at that lens scale, now where do you go? OK, because space becomes not continuous,
all sorts of things happen and the whole idea of string theory is to limit the size you
can go. There s a fundamental size, and you can t go beyond that, OK? Now, the amazing
thing about this is, it has to do with physicists faith. If they think they got something, they
re willing to extrapolate by, this is about 26 orders of how many orders of magnitude?
Nineteen orders of magnitude from where we are today? OK, that s a lot. So just as and
so we know gravity, when you extrapolate to the size of the universe, so far seems to
work going back down the other way, so maybe, in all that, maybe 26 orders of magnitude.
It s going to s not going to be consistent with the fundamental quantum theories. So
we got a problem, OK? But we want a problem that we can solve one step at a time. (Chuckles.)
And so that s the exciting thing about this. Does this particle have all the properties
it was supposed to have? Not determined yet. He will talk about that. And but is there
a sign of some new physics in a range where the current Large Hadron Collider or the upgrade
to that or a new machine that the world can indeed build, give us those answers. So with
that I think it was 10 minute introduction, it s my pleasure to give the remaining five
minutes to professor (laughter) Incandela. (Applause.) JOSEPH INCANDELA: Hello. Is it
working? OK. I hope to fill the details in a little bit. So this is a picture of the
CMS experiment. I ll come back to this later. So for my talk, I decided to call it and sometimes
I do this title my talk searching for the genetic code of the universe, and discovery
at the LHC is what I want to talk about. So to say that you re looking for the genetic
code of the universe sounds pretty big. You know, it s like let me explain to you. It
may not be so big as you think. I told the I had a graduate student friend and who was
working on string theory at the University of California Santa Barbara where I m professor,
and I asked her, are you interested in what we ll learn at the LHC? And she said no, not
really. I said really, why not? She said, well, it only pertains to this universe. (Laughter.)
So, you know, this is actually a rather modest topic. (Laughter.) OK, before I get started,
I have to tell you a bit about particle physics and the standard model. I won t be going into
great detail on the theory, but let me just tell you some things. I have a lot of slides,
so I have to move somewhat quickly. OK. The standard model is took about a hundred years,
and it s a combination of quantum field theory and the discovery of many new particles, led
to what something like a periodic table. A new periodic table of fundamental elements,
and this is what s shown here. You have quarks, leptons and the particles that carry the forces
between them. As Carlo Rubbia once said, we a hundred years and billions of dollars, and
this is all we know. (Laughter.) But actually, this is what we want. We want it simple. So
this is a very simple view of things, and it s remarkable that the universe, in some
sense, is this simple. There is a piece that s been missing, which is the Higgs. And it
s a very important piece, and this has been one of the greatest achievements of 20th century
science. There s no doubt about it. Now interestingly, there are some strange things that we don
t fully understand. These are the quarks the six quarks which have all been now discovered
and studied. The top quark is incredibly heavy. It s actually heavier than a gold atom, and
we don t really understand these things. Why are those these different scales and so forth?
So there are many things we have to understand. So coming back to this table, again remarkably,
this model is probably one of the best-tested models in history. We ve done hundreds of
measurements, sub percent level. Everything holds up. What we see in the universe are
these things. We see the up and down quark and the electron. The up and down quark are
the quarks, really, that make up the neutron and the proton. So that s what makes up atoms,
these three things here. In some sense, we do see the effect of this, but we don t see
neutrinos, and yet there are sort of three sets of these particles. There s one missing
piece, and that s the Higgs. That was the missing piece ll talk about that. It may still
be we don t know, but I ll tell you what we ve got. Now, while developing this fundamental
theorem theory of fundamental forces and interactions, physicists hit a snag and this is what Secretary
Chu was talking about but the particles that carry forces had to be massless, but the data
seemed to say otherwise, OK? We see we see that the force the weak force was very short-range.
And in fact, why do any particles have mass, and what is mass? We didn t have any way to
explain this. Now, massless particles move at the speed of light. The speed of light,
as you know, is 186,000 miles per second. We know that energy is related to mass, so
if a particle has mass M, its rest energy is MC squared, but if a particle has momentum
P this is the actual formula that you use, from Einstein s equations and so if a particle
has no mass, there s still this piece left over. The energy is equal to momentum times
the speed of light. And this is the equation, basically, for a particle moving at the speed
of light. So there was an ingenious idea that came along. Suppose there s a force field
filling the universe that somehow slows particles down to below the speed of light. This would
make them have mass, and that was basically what this Higgs field introduction was to
be. So here s kind of a graphical representation of this. Particles are moving through the
universe through the vacuum we call it a vacuum and there s a field, there s this Higgs field
that permeates the entire universe, and some particles interact with it more than others.
And the more they try to increase their momentum, the more they interact. Other particles don
t interact. The photon, for instance, doesn t see this at all, but all the other particles
that have mass, all the fundamental particles, interact with this field, and it slows them
down. OK. Is it a field or a particle? Fields have very small packets of energies associated
with them called quanta, as Secretary Chu mentioned. Elementary particles interact by
exchange of field quanta. So here I show, for instance, the exchange of a photon for
the repulsion of two electrons, OK? This is not so hard to believe, OK. But it gets a
bit more counterintuitive with more complicated processes. In fact, it gets very, very, very,
counterintuitive. So, OK I already told you that E equals MC squared. Now it turns out
that a particle and an anti-particle could just pop out of empty space and then return.
We call this the vacuum and this is a vacuum fluctuation and then vanish again, OK? These
are virtual particles, and it s a very important part of the universe. It has very far-reaching
consequences. The structure of the universe actually depends on particles that don t exist
in the usual sense but did when the universe was very hot and very young. And in some sense,
this is the reason we do what we do. We re trying to understand what particles could
exist because they actually have an impact on the structure of the universe and particles
that do exist that we use and see. So I ll show you some more on this. Now, for example,
top quarks were seen for the first time at the Department of Energy s Fermilab near Chicago,
and this is a top quark event from the early 90s. Now, what makes us so sure about the
Higgs? The Higgs theory has predictable consequences. It predicts very heavy force particles that
carry the weak nuclear force, W, the W plus, W minus and zenot (ph). In fact, it s designed
to do this. These should have a mass about 80 juv (ph) and the Z should have a mass of
91.1. The proton has a mass of about 1 juv (ph). So these are very, very massive particles,
as was mentioned earlier. We should be able to find them and measure their masses. In
fact, for example, the Z should decay the two muons sometimes, and we can calculate
we can take and measure the momenta of the muons and reconstruct the zenot (ph) mass.
And if we do this many times, we get a distribution for the mass values that has a very predictable
shape. In fact, we predict the shape for many thousands of Z to mu events to look like this,
OK? You have a peak at 91.1. This is what a mass peak looks like. There s some backgrounds.
Actually, this is from top quarks producing two muons. But this is what we see. So we
get very close to what s expected. We know that there s something that is engendering
mass to these force carriers, and the Higgs the Higgs mechanism, as it was portrayed,
it was a mathematical trick, but it worked incredibly well. It gives you exactly what
you want. Now, moving on, there are fundamental connections, as I said before, between particles
let me get some water. I m afraid I have a cold, so I m a bit dehydrated. There are particles
that we don t see that have an impact on the particles that we do see. So the mass of the
W depends a lot on the mass of the top quark and the mass of the Higgs, in fact, OK, through
virtual interactions. And these are the kind of interactions I ll show you in a minute.
And this is because a particle s identity really cannot be so well-separated from the
things it can transform into in field theory. So for instance, here you see a W decaying
to a well, not decaying but actually transforming into a top and a bottom quark and then back
into a W, OK? This is one of many possible diagrams that determine the mass of a W. And
the W, in some sense, is a top and a bottom, is a charm and a strange. All the time all
of these things are sort of happening in reality, but in a virtual sense. Similarly, a W can
basically transform into a Higgs and a W and back into a W. So this is sort of the strange
part of quantum field theory and one of the things I have the hardest time trying to explain
to people, but I think it s one of the most interesting things about what we do. There
is a vacuum. We call this vacuum. You normally would think of the vacuum of outer space,
if you took all the atoms out and all the light and so forth, as completely empty. But
in fact it s kind of a teeming foam of quantum possibilities. And when a particle passes
through the vacuum, it actually can create and interact with it and become, if you like,
a much more complicated thing. So it depends what determines the vacuum. What states can
exist actually determine a lot about the particles that we see. OK, so the upshot is if you were
to measure the top quark and the W mass very precisely, you could predict the mass of the
Higgs in the standard model. And in fact, this is what we ve done. We know the top mass
now at a very high precision from Fermilab very well, and we know the W mass also from
Fermilab very well. And so we can plot the W mass versus the top mass, and with their
uncertainties, we find that in this plane, we re basically expecting well, I m sorry,
this actually shows you the measurement with its uncertainties. This is about 70 percent
probability. That s where we think these two masses would lie. Now, these diagonals tell
you what the Higgs mass would be, OK? The gray region was actually ruled out. I don
t know if you understand this. Some plots sometimes it s very difficult. But you see
the diagonals; this corresponds to 114 GeV, 300, 1,000 roughly 110 times or 114 times
the proton mass, 300 times the proton mass and so forth. We make these measurements,
and it tells us the Higgs should be basically between these two red bands, OK? But the gray
whole gray region was ruled out, OK? So we think, giving ourselves a little leeway, that
the Higgs must be between where it was ruled out out to about here. And that corresponds
to the range from 114 to 185 times the proton mass, roughly speaking. And again, we know
this because we know that the W is affected by the top and the Higgs. OK, now, the problem
is there is one big problem. The Higgs actually solves a big problem, and it explains why
we have mass for these elementary force carriers, but it creates probably many more problems
than it solves. Now, virtual as I mentioned before, virtual particles contribute to the
Higgs mass via these what we call loop corrections, but it s really that the Higgs can transform
into other particles. And here I show you, for instance this is a classical diagram for
the Higgs if it had no quantum interactions. But it has interactions with all of the fermions.
All the particles that are in the standard model, it can interact with in a virtual way.
And that affects its identity in the way that I mentioned before. OK, when you calculate
the Higgs mass, you find that there s a correction due to this effect, which is huge. This factor,
lambda, is Planck-scale, and it s about 10^19 times the mass of the proton. So we find that
as soon as we try to calculate the mass of the Higgs, it goes berserk, extremely high.
This is what s called the hierarchy problem. And there s something to that s needed to
cancel these effects out, OK, or the universe may, by chance, be unbelievably well-balanced.
It turns out that if you fine-tune all of the constants in the Standard Model, all the
masses, all the couplings and so forth to about 30 decimal places, everything works
out. But we don t usually run into those kind of circumstances in physics. If there s really
there s usually something that creates a state of balance, an equilibrium, not such a fine
tuning that, you know, would require 32 decimal places. Well, it turns out if you actually
bring in a new set of particles with roughly the same masses, you get a cancellation, if
the particles are different spin. And this is essentially one of the things we think
may be happening in the universe. OK, we think, first of all, you have to have these partners,
and you add these terms; you get a nice cancellation. There s a much smaller term that s left. It
too becomes large, though, if the partners if these particles are much more heavy than
these particles, you start to get fine tuning again. But all indications are that these
particles should be in the range of the LHC, and the question is what are they. How do
you get partners to all the Standard Model particles? Well, you can introduce a very
basic symmetry and say that for every half-integer spin particle particles have half-integer
spin or integer spin. If it s half-integer, it s a fermion; if it s integer zero, one,
two, et cetera s called a boson. So if you ever wondered where those come from, these
are two physicists, Fermi and Bose, and these are two different types of particles, depending
on their spin. So you need a in this in this idea of supersymmetry, basically, you create
for every particle that exists, if it s half-integer spin, you create an integer-spin particle
that corresponds to it, and vice versa. And this is what you get. You get a whole new
set of particles. In some sense, it s like a mirror image of the particle structure of
our universe. And this is one of the things we think is worth searching for. But I won
t talk about that in great detail. I will mention a few things that are nice about it.
We talked m sorry, Steven talked about unification. If you look at the forces for the for instance,
for the weak, strong nuclear force and electromagnetism, these coupling strengths which are universal,
they depend on what energy you re working at. The strength actually changes with energy.
And if you go to higher and higher energies, which is basically going back toward the Big
Bang, this is what you get. They kind of don t get very close. If you introduce this supersymmetry,
they actually merge to a point. And one of the greatest physicists I know, Ed Witten,
said this is, for him, the most convincing argument why supersymmetry may really exist.
So this is one of the thing we re studying at the at the LHC. And as Secretary Chu mentioned,
if we only see a Higgs now that has only the properties of the Standard Model, we don t
know how is it how is its mass being obtained? How is everything working? How is everything
so well-balanced? What we d like is to find some indication that it s not Standard Model
and some indication that it may be represented by something in supersymmetry, for example.
So there s something worth mentioning, though. Supersymmetry generally predicts that there
exists a Higgs particle that s very much like the Standard Model Higgs but very light, under
130 GeV. And remember, the range that hasn t been ruled out for the Standard Model was
114 to 185. So things are kind of lining up. There s one other thing. There s a connection
to dark matter. As you know may know I think there was a talk here about dark energy not
long ago. It was observed that if you look at stars and see how they re moving in galaxies
as a function of the radius from the center of the galaxy, you d expect that as they get
further and further away, they would be less connected and move more and more slowly, along
a line like this. But in fact, this is what s been observed, that they actually increase
in speed. And it s as if there was some heavy material that was holding them all together
like rice pudding and spinning them around. And so we believe and there s a lot of evidence
now that the universe has this material, which we don t know what it is, called dark matter.
So moving to the dark side (laughter) m almost done with the theoretical part of the talk.
We know that about 5 percent of the energy in the universe is ordinary matter. That s
all. We re really in the minority. We know very ve done all this work and thought we
understood everything, but it s only about 5 percent of the universe. We re really not
doing so great. And we have to do better. Twenty-five percent is dark matter. And SUSY
theory, supersymmetry theories, predict exactly this, if you like. This was kind of a miracle,
they called it at one point, that the supersymmetric theories not only predicted this beautiful
unification, not only solved the problem of the Higgs mass but also predicted dark matter
at about the right abundancy. But there are other possibilities. SUSY is the favorite.
As I said, it produces a nice dark matter candidate, leads to the universal forces and
fixes this hierarchy problem with the Higgs. The remaining 70 percent is dark energy, OK,
and I think it s fair to say we have fewer good ideas about what this is, although it
s evolving rather rapidly. But it ll probably be (taxed ?) someday, for one thing. (Laughter.)
Deparment of dark energy? (Laughter.) Has that been mentioned? No. So I anyway, OK.
OK, or maybe not, all right? The absence frankly, we ve been searching for supersymmetry for
years, and we have no evidence at all, none. And some theorists are quite depressed about
this. We ve looked at every accelerator; we find nothing. And that means maybe it s something
else. And there are many theories that have appeared to try and fix all these problems.
Usually they re like supersymmetry in introducing new particles that balance out this problem
with the Higgs, but sometimes they introduce new spatial dimensions. And they do that because
if you do add small spatial dimensions that you can t see, it turns out it makes this
very high-energy scale that I mentioned come very far down, and then the problem kind of
disappears that way. So one way or another, either we have a mirror image of all the particles,
or we have additional dimensions, we think, to solve this thing, or else everything is
extremely well-balanced by chance. Those are the three options. OK, so there are lots and
lots of theories that try to solve all these problems. And we re studying all of them,
actually. And in fact, if you don t know exactly what you re looking for, a Large Hadron Collider
is actually the very best tool you could use. And that s what we use. So let me show you
a picture. This is the LHC accelerator complex viewed from the Jura Mountains. And so you
can see how enormous it is. This is the actual LHC, this yellow line. This purple line is
a smaller accelerator that is used to inject into it, and here s another one. Here s Mont
Blanc. My house is right over there. (Laughter.) But it took many, many years to paint those
stripes, by the way. (Laughter.) That is one of my favorite views. Now, there are two really
big experiments. Here s another view. And actually, you get a better feel of how big
this thing is, because this is the Geneva airport, OK. So it s really huge. And there
are two multipurpose detectors called ATLAS and CMS. I m the head of the CMS experiment.
And I ll talk about both very, very balanced mostly CMS, of course, but (laughter) and
then there are two other experiments, LHCb and ALICE, I won t talk about. These are doing
very interesting physics, but it is very, very specific problems that they re trying
to solve, which we are also trying to do in these two big experiments. And this shows
the complex. There s a little linear accelerator that goes to a booster ring to another ring
to another ring and finally into the LHC. And the reason you do that is the energy range
you can push particles depends on how far you can change the magnetic fields of your
magnets in the accelerator. And typically, it s a factor of 10 or 20. So to get to very,
very high energy, you need many stages, and this shows what those stages give you. Now,
I ll tell you some facts about the LHC, because it s pretty amazing. This shows the two beam
lines, actually, in a dipole magnet. It s all one magnet system, but there are two beam
two beam lines side by side. OK, for the tunnel, it s 3-meter diameter, 16 miles around around,
and there were 2 billion pounds excavated. For the beams, they re made up of bunches,
and they re separated by 50 billionths of a second, which is about 15 meters right now.
In fact, they ll cut that in half pretty soon. Now, at the interaction points, the bunch
length is pretty small, and the beam radius gets squeezed down to less than a thousandth
of an inch, which I think is pretty amazing to have a machine that s 16 miles around and
then be able to do something at the level of a thousandth of an inch. And this is a
branch of physics I don t really participate in, accelerator physics, but it s really quite
amazing. And the rates at which we have collisions of these bunches about 32 million per second
eventually, but at the moment we re running at about 16 million per second. OK, I won
t go into great detail here, but just to say that everything is kept very cold, 1.9 degrees
absolute, so it s the world s largest cryogenic system. It s colder than space, and it s emptier
than space. And it s like Swiss chocolate. (Laughter.) You were wondering about this,
aren t you? (Laughter.) OK, so the magnets if we go to the highest energy possible, each
of these magnets, of which there s over a thousand, stores about 7 million joules of
energy. Together, it s 10.4 billion joules, OK. This is way beyond any previous accelerator.
And it s enough to melt that energy is enough to melt 12 tons of copper. And it s the kinetic
energy, actually, of an A380 moving at 700 kilometers per hour. The energy stored in
the beams, actually if you look at one bunch, the kinetic energy is 129,000 joules. For
all the bunches, you re up to 362 million joules. That s equivalent to 90 kilograms
of TNT or 15 kilograms of chocolate. (Laughter.) I bet you didn t know chocolate had so many
calories. (Laughter.) And then what happens is the two beams they get squeezed. This shows
an actual simulation of what the what the magnets do to squeeze the beams. They fire
them at each other, and they cross. And it s equivalent geometrically, but at a much
smaller scale, to, they say, shooting two knitting needles from either side of the Atlantic
and having them hit head-on halfway over. And that actually is done by devices that
were built in the U.S. In fact, there were many U.S. contributions. I won t go into all
this detail. But these focus magnets came from Fermilab; there were separators from
Brookhaven many operational contributions, and lots almost all the R&D for future accelerators
is going on in the U.S., OK? OK, I move on to the experiments, ATLAS and CMS. This is
ATLAS. I all the slides I got from the for ATLAS are from the spokesman of ATLAS spokesperson,
Fabiola Gianotti. So these detectors are very complex. They re the most complex ever built
for our field. They re the largest. It s a very big jump in technology. To give you an
idea of how big this is, this is a person, OK. So it s a very large detector, about 45
meters long, 25 meters tall, very fast response and can handle a huge amount of data very
quickly. And I ll tell you a bit more about this. Let me show you ATLAS as it was being
built. This is the cavern in which it was installed. These are people, for scale in
2003. And then you see how it goes together. Voila. And there s a picture. So this is a
huge detector. And all of this now is filled also with detector elements. These are big
collaborations, many, many countries. In fact, there s about 38 countries, 176 institutions,
3,000 authors. About 1,800 are Ph.D.s, about 900 graduate students on this experiment.
And then you can see U.S. ATLAS has 44 institution, about 600 authors and 170 graduate students.
And this shows you the distribution. It s not a vote map. Now, let me tell you about
my experiment, or at least the one I m leading at the moment, Compact Muon Solenoid. It is
it was interesting because we had to build it on the surface and then lower it. So it
had to be built in pieces, and so it s rather modular, and it s rather small, compared to
the other one, actually. It s very compact. Because we have an extremely strong magnetic
field. The key is, when we when we collide particles, new particles come out. We turn
all the energy of motion of the two protons into energy to create new particles. When
the particles are charged, they come out. We use magnetic fields to make the particle
trajectories arc, OK? They get bent. And the curvature tells us their momentum, so we really
need to know that. These particles that we re producing are so high-energy that it s
quite hard to bend them, OK? So either you use a typical one (Tesla ?) magnet, say, and
a very large distance in order to see the arc which is what ATLAS does, to some extent
or you go to a very, very strong magnet, OK? We go to a very, very strong magnet, and this
allows us to bend the particles directions in a much smaller size scale. And in fact,
it s not even that small, but it this is our detector s much smaller than ATLAS, but you
can see, this is the magnet. So it s not so small. OK. And this is the last time the detector
was actually open. This is a view looking down at the central region. OK. Let me give
you a quick tour of CMS. I don t have the nice collage of photos, but this is the (inaudible)
when it was empty and this shows when we lowered these pieces. This is 2,000 metric tons, about
4 million pounds; had to be lowered with a huge crane. And there were four straps. There
s a high school I gave a talk on this once at a high school, and some high school student
said, well, what do they use for these straps. And I said, I have no idea. You know, I really
don t. I went back and discovered that the straps are each made of 55 steel cables over
an inch thick that go to separate reels that are monitored by individual engineers so that
they actually form the strap as they lower it, and they monitor all the tension so that
they don t create any torsion or swing, because we only have three centimeters clearance.
I mean, it s not so it s pretty amazing. There s many, many interesting engineering feats.
Now, we actually turned some brass casings from the Russian military there s a happy
guy (laughter) into our Hadron Calorimeter, OK, as you see here. And this is a calorimeter
measures calories, it measures energy. OK, I mentioned this. This shows you the cabling
and cooling lines coming in. This is like was over it was a bit of an oversight. We
just said, oh, we ll be able to take care of that later. It took about two or three
years of engineering and 50,000 man hours to lay all of this out. And this shows the
last pieces getting installed, the tracking system, and then we re ready to close and
this is what it looks like closed, which is not very pretty. But that s how it is at this
very moment. Here s the (beam line ?) coming in. There s one on the other side doing the
same. This is the collaboration part of it. It s only about an eighth of the people involved.
This is a life-size photograph of the detector. And we have about 4,000 science, 800 Ph.D.
students m sorry, 4,000 includes engineers. We have about 3,000 scientists, like ATLAS.
We have 41 countries and 190 institutes. And this shows the U.S. distribution, 48 institutions,
450 Ph.D. physicists and about 200 graduate students. OK. Now, interestingly, Newsweek
came out a few years ago with this saying, this is the biggest experiment ever, and it
s European. And of course, the news always gets it wrong. First of all, ATLAS is bigger
than CMS, and this is a picture of CMS. (Laughter.) So they screwed up. Second of all, oh, here,
I see. The U.S. is very much welcome by the Europeans. But second of all, actually, everything
you see in this picture was built in California. (Soft laughter.) The U.S. has a big contribution.
We re the biggest contributors to these experiments, about one-third one quarter to one-third of
the equipment and about one-third of the people very big contributions, as I mentioned, to
the LHC. And we really thank DOE and NSF. It s really been a fantastic experience. There
are also many U.S. labs and universities involved that contributed. Anyway, so how do we reconstruct
what happened in the collision? This is the more practical end of things. Let me just
show you. This is the detector before we put an (end cap ?) on it, and I thought it was
a good picture to show because you see the cylinders. And basically we just have nested
cylinders, many, many of them. As the particles move through them, we get signals, either
to track the particles or later to try and stop them and measure all of their energy.
So this is kind of a little cartoon diagram of what s going on. And you see, you have
many layers. On the inner-most layers, we use silicone detectors very, very lightweight
and we try not to deflect the particles. We want them to move through without any almost
seeing nothing, OK? We want to actually measure their trajectories in the magnetic field.
We look at the bending, and we get their momentum. Then we put them in the path of basically
lead tungstate crystals, really heavy crystals which will stop any kind of electromagnetic
particles, namely electrons or photons. And that s this region here. You see you have
an electron that basically stops and showers tons of energy, and we measure that energy
very precisely. If it s a hadron which is like kaons, pions, protons, something like
that we use the brass, the picture you saw before the brass stops them. And the only
thing that gets through everything is a muon. And so if I go back here, all these red chambers
out here red m sorry, the red is iron. The silver are detectors for particles, and those
will detect muons. And that s basically how it works. And very close to the beam we have
a super high-resolution pixel detector with about 70 million pixels that we can use to
actually measure things so precisely, we can tell if a particle traveled a little distance
before decaying. So we can actually measure lifetimes of particles to about a trillionth
of a second, that way. This is the first collisions on March 2009. This is me. I was running the
operations for the experiment, and the press was supposed to stay back there. But if you
tell the press to stay somewhere, they don t stay there. So this guy snuck up behind
our who was from Reuters, from behind all of our control panels and managed to get this
fisheye picture of us. So we collide beams, OK? So we have two beams circulating opposite
directions with one oops 1,380 bunches at the moment. Each bunch has 160 billion protons.
The bunches cross at four places. And in fact, despite the fact that they re squeezed to
only a thousandth of an inch or less, and despite the fact that there are so many protons,
we only get 20 to 30 pairs actually colliding. Protons are very small. And so you get a collision.
And most of the time, they re not very interesting. The protons break up. It turns out quarks
can t be separated. As soon as you try to pull a quark out, it creates a new one to
pair up with it. So you get processes like this, where you turn quarks into various kinds
of hadronic particles, nuclear particles that don t live very long themselves. Let me show
you what a what one of our first events looked like just so you get a picture of what s going
on, because it s important that you visualize it. And this is happening 16 million times
per second, OK? This is one of the first events we took year with the highest energies. So
you see all the layers of the detector there. The bunches cross, and that s what happens.
We have 20 proton pairs colliding, and all of these particles come out. And that s a
real event, and we really can reconstruct all that, and with that kind of detail. now
more interesting events are when you have a very hard interaction. The protons just
don t break up with the quarks inside or the gluons inside actually collide very high energy,
and you can produce interesting things like a W, which I told you about before. This is
a fine Venn diagram showing a u and a dbar quark interacting to produce a positive W,
which decays to an electron and a neutrino. And let me show you even a more interesting
event. This is a Higgs possible Higgs event. It s a candidate Higgs event. Very possibly,
in fact, this is a Higgs event that we saw, where the Higgs decays to two Z s, and the
two Z s decay to electrons, one pair one to electrons, one to muons. It s a bit of a mess,
right? How do you dig this out? Well, let s see if I can stop the thing, right? Probably
can t. Did you catch that? (Laughter.) Well, what happens is let me do it real quickly
again you see lots of tracks that are curling a lot. They re not very energetic, but you see
these color tracks here deposit lots of energy only in electromagnetic section or only in
the muon part of the detector. In fact yeah. So I don t know how to stop that. But we know
that that is a pair of Z s. We can reconstruct the two Z By the way, I just show you heavy
ions because it s cool. (Laughter.) When you smash two led ions together, it s quite a
spectacular thing. These are two very, very high-energy led ions that collide. And for
us, what s amazing is that the detector can actually handle that. There s never been detectors
in the past that could do that, to my knowledge. OK. It s a camera. We often call it a camera.
It takes a picture. It has many, many pixels. So you can think of it as these detectors
as cameras. They have 80 million pixels, but they re obviously not ordinary cameras, for
several reasons. They re designed to take up to 40 million pictures per second, which
is pretty impressive. The pictures are three-dimensional. They re extremely precise, to a few microns,
a few millionths of a meter. And at 15 (million) and 31 million pounds, they re not very portable,
these (inaudible). But they re pretty good. Now the challenges are that we have these
16 million times per second. And if we were to take each of those events, which is about,
I don t know, a couple hundred kilobytes, you could imagine how much data we d be collecting.
We just can t handle all that data. So what we do in fact is we look for the more interesting
ones, which are rare. For instance, the Higgs are one in a trillion, basically, but we look
for not something that rare, but we look for very rare things that are interesting. And
we keep only about a thousand events per second, OK? That s all. So we have to pick the good
ones and we have to pick them fast, so we use triggers. And the triggers basically,
first, we do kind of a millionth-of-a-second analysis, very quick, and we decide, this
is interesting. And if it is, we keep it, and we keep about a 100,000 per second, and
we feed those to a farm of about 10,000 computers with Gchat in about a 10th of a second to
say, is it worth keeping or not? And we keep the 400 to 1,000 best of those. And we still
end up with lots of data. We have about 22 petabytes per year of data that s distributed
around the world. You can see the distribution. And I think I have a little yeah, this is
for CMS. It shows you how we distribute data. First we have from CERN we go to seven giant
computing centers. One is in Firmilab. And from those they go to a set of smaller ones
around the world, and then from those to yet a smaller set. So we have something like a
hundred thousand processors working for us at any given time. And remarkably, we can
get the data distrusted worldwide in six hours, which is pretty impressive, I think. Now,
I won t show a lot of results. I don t know how well you read plots and so forth, but
the point is here, this shows kind of the rate at which this process occurs. The bigger
numbers means it happens more often. And this is a production of W s. In this plot, at least,
it s the most common, then Z s, then top quarks single top quark instead of a pair a pair
of W s, a W and a Z, a W and a top quark, two Z s, more and more rare processes. These
are factors of 10. Then we studied these, and you can see, where these orange bars are
that are horizontal, that s what s predicted. And these little blocks are what we actually
measured. So we did the same thing. We have very fantastic agreement also in CMS, same
idea. So we understand all of the processes we should understand, and we measure them
all as we expect. So this allows us to move on to the Higgs. So, Higgs searches. Excuse
all the graphs, but it s hard for us not to show graphs in my field, but don t worry if
you don t follow them very well. The basic idea here is that we don we have a theory
for the Higgs which allows us to predict everything you could possibly know about it but its mass.
We don t know its mass. So at any given value of the mass, we could tell you for instance
how frequently it s produced and how it s produced. For instance, this red line corresponds
to two pairs of gluons actually fusing into top quarks to generate a Higgs. This sounds
pretty far-fetched, but we think it s real, and there s indications that it works. There
s another way you can actually fuse two W s or two Z s and they kick out a Higgs. So
these are different production modes. And you can see as you go to higher and higher
mass, it s less and less likely you produce them. And then when you produce them, again,
depending on the mass, they will decay different ways so a somewhat complicated animal. If
they re very, very massive, they can decay to very heavy objects, like W s and Z s and
top quarks. These are the most massive particles we knew of. But if it s light, it can decay
also to light particles. So in this region, which is where we said it would be most likely
to be found, you can see we have the most complicated set of different decays. By the
way, all these different curves add up to one. So it s just saying, there 100 percent
probability it decays to something. This is the relative proportions into different things.
And this is how we d look for it. If it decayed to two photons, we d have a huge background
as a function of mass of just random pairs of photons, basically. But the Higgs would
appear as a little bump, OK? Same thing for Higgs decaying to two Z s: We d see if the
two Z s decayed to four electrons or muons, we can reconstruct it and it makes a peak.
So part of what we do are look for bumps, as I d shown you before, for the Z, looking
for bumps for the Higgs. And I will show you the bumps that we found and they re pretty
small, OK? But they re very significant. All right. I don t know if I m going to go through
this in great detail, but what we did this is an old plot from basically about a year
and a half ago or less, where we d searched for the Higgs. And if it were a standard model
Higgs, it should be along this red line. And we predicted our sensitivity could be looking
for something that s produced even more rarely, OK? So as you go down, it s more and more
rare produced. And the black line shows you where we actually kind of sit with our experiment.
So anywhere you see the black line below the red means we can rule out the standard model
Higgs at about 95 percent. So you see there s a big range over which we ruled out the
standard model Higgs. Up here, though, where it s above the dashed line, what we re observing
is much higher than we expected, OK, from just background processes. This tells you
there could be something there. I m going to skip through this. So these are more recently
what we showed at the end of last year in CMS. This shows you, again, we can rule out
everything where the black solid line is below the red, so a big range of the mass. But there
s something here, which now I have blown up and you can see the data somehow is much higher
than you d expect if it were just standard model backgrounds, OK? So we re seeing some
excess of events around 125 GeV, but it s just a hint. Interestingly, though, ATLAS
saw the same thing. About 125, we see a bit of an excess, but it was very statistically
insignificant, so we made no major claims about this. And we moved on to 2012 and we
started looking. But at the end of last year, remember I showed you before that we thought
that the range that was available was sort of 114 to 185. With these experiments we had
ruled out a lot more. And interestingly, this is green region here was predicted by Fermilab
this is, again, the W mass versus top mass the Higgs bands and we d wiped out this whole
region here that s white. And the only place a standard model Higgs boson could sit is
right here, which is about in the range of 115 to 127. So that s where we decided to
look very carefully. This was the main story last year, by the way, that we squeezed it
into this little tiny space where it could live, if it s standard model, and that s what
led us this year to really focus on that region. So I m going to show you our results now very
quickly. Again, it s a little technical to show these things, but I hope you ll follow
it OK. So we saw these tantalizing hints of an excess. So what I want to show now is the
cases where we would see a bump, mostly Higgs to ZZ, Higgs to two photons. I ll show results
for W s, but W s don t give you bumps, so I m not going to spend a lot of time on those.
Anyway, this is a display of an event in ATLAS for Higgs to two photons. Here you can see
a map of the energy, and this is kind of (five ?) versus angle theta, but you can see the
two photons produced here. What we re dealing with, though, are many, many interactions.
And the photons have no charge, so we can t track them. And we have to figure out which
one of the interactions it came from, so that s one of the complications. It makes it very
hard. You have to know where it was to within about a centimeter, which doesn t sound too
bad, but this all of this activity that you see here is within a couple of centimeters.
So you want to try and find out where the photons came from, which proton proton interaction.
This is an event in CMS. You can see lots of debris from the proton, and then two photons
just really back to back, shooting out like this at about 125 GeV. So this is a really
interesting event. So we look, and this is a probability plot. Now, if we see an excess
of events, we can ask, what s the probability that just background events would produce
this, not some new signal? And what you find is that if we combine the 2011 data and the
2012 data, the probability is extremely low, less than, you know, something like a hundred
one in a 100,000 or something like this, so or one in 50,000. So this is this is where
we stood on this case. And you can see if you look at it in terms of standard deviations,
it s more than four standard deviations. So this reaches the point where we really think
we have something. But this was done using statistical tools, and it s hard to visualize
it, OK? So what we do is then we combine the data for all the channels, and sure enough,
right at about 125 we see a bump. It s a rather tiny bump, OK, but it s a very significant
bump. And there s nothing else like it anywhere else. So this is our strongest evidence that
we found a new particle. ATLAS has similar results. You see a very nice bump, OK? These
are just two different expressions of the same data. And they also calculate that for
this to happen just from background is very, very improbable, about 4.7 standard deviations,
one in, you know, almost a million, OK. And this shows you that the next search that we
look at carefully which the Higgs decaying to two Z s and the two Z s each decaying to
two pairs of electrons and muons. And this is a beautiful event in ATLAS where you have
two electrons I think these are actually all electrons, OK. These two match up to one Z
and these two to the other Z. And again, we look for a bump. Now, you get a bump here
from just Standard Model production of pairs of Z s. What we re interested in is to if
there s a bump somewhere below. And you see, in fact, there s a very nice little bump here
at 125, OK. So now we have indications of something in two channels this is this little
bump. But it s weak. You know, it s not huge. OK. So this shows you the results. ATLAS now
has been able to rule out all of this region that s in red. And this shows the probability
for those events to be background events for the Z s. And it s about, you know, one in
10,000-something. This is an event with four Z four muons, two Z s and CMS. And CMS also
looks for a bump. And we see a little bump also at 125. So you see, we re seeing in all
these in both of these experiments, in both of these channels, little bumps, OK, but they
re exactly at the same place. And when you add them all up, you get a very significant
statistically very significant result. Here I show the CMS results. It s very improbable
that this came from background. The lower this dips, the more improbable it could be
from background. So if we combine those two channels in CMS, you get five standard deviations.
And that s the kind of the official level for discovery. Our expectation was about 4.7
ATLAS, similarly. In fact, if they add in the W s decaying to electron, muon plus neutrino,
they get six standard deviations. And that s what you have. This is CMS adding in the
W s and all the other channels. We still stand about five standard deviations, OK. So these
are the final, final results, very improbable that this could be coming from background.
We both see excesses at about 125, in both cases, extremely improbably. Voil Now, what
s interesting to look at is how things match up to what you expect for the Standard Model.
And I think I m almost done. But you see, in both experiments actually, Higgs to two
photons tends to be much higher than what you d expect for the Standard Model. That
s this dashed line here or in this case it s this black line. About 1.5 to 1.8 times
higher than expected. And that was true in both years. If you look if you dissect the
data into two years, in both cases it s high in both experiments both years. ATLAS has
not yet looked at Higgs decaying to spin-half particles, CMS has. And interestingly, we
don t see much indication. Although the arrows are very large, we re basically at zero here
and a little bit above zero here. So this is actually what we re working on now. We
re trying to get more data. We have lots more data. And by the end of the year, we ll have
three times more data. These arrow bars will get much smaller, OK. And referring back to
what Secretary Chu said, if it s Standard Model Higgs, all these things should start
to line up with this number one basically line up with one here, line up with the dashed
line there. But if we stay high, OK, for instance, with the photons, and the arrows become very
small, then we have a very significant discrepancy with the Standard Model. And that would be
very exciting difficult to explain, but extremely exciting. Similarly here, if the taus stay
at zero, and the decays to fermions spin-half particles don t occur, that means we have
something very exotic. At the moment though, everything is still consistent because the
uncertainties are large. So we can we can t yet rule out that it s Standard Model Higgs.
All right, other things we look at are the mass. These plots just show you the probability
as a function of the mass. There are contours in probability of signal versus mass. And
you can see that we measure the two experiments measure around 125 or 126. ATLAS is 126. We
get 125.3 very close. The uncertainty is no problem, so we re consistent. The next thing
we want to do oh, let me mention, Fermilab also has some evidence. They look for Higgs
decaying to bb-bar, for example, or to WW and they see quite a big signal in the same
region for Higgs decaying to bb-bar. So this is corroborating evidence. The big question
though to tell us whether it s a Higgs or not is whether or not its spin is zero, OK.
This is a big issue. And we know its spin has to be integer, because it s decaying to
two photons. It has to be, in fact, even. So it s either spin zero or spin two. And
the question is, can we separate these? And these plots just show you, to some extent,
how well we ll separate by the end of the year when we have this much data. Ignoring
the plots, you can look at just the standard deviations if you like, we think we ll able
to tell zero from two at about four standard deviations. And I think if turns out that
it s zero then we ll be sure it s a Higgs and somebody will probably get a Nobel Prize.
Not me, but somebody named Higgs perhaps, I don t know. Now, to know it s Standard Model
or not will be very hard. In fact, the Large Hadron Collider, we won t be able to tell
that. If it if it continues to look Standard Model no matter how far we go, we won t be
able to say with 100 percent confidence that it is Standard Model because there are many
other models that predict a low-mass Higgs particle that is very much like a Standard
Model Higgs. All right, so we just submitted our papers last week. New boson has been found.
It s 40 years 48 years since this was predicted. It s 20 years it took us to design and build
these experiments and accelerator; it was three years to acquire the data and a generation
of intense effort for about 6,000 physicists to get this data which is pretty remarkable.
So what s next? We got to figure out what it is (laughter) and see where it may take
us. And in fact, the Higgs may be a portal to new things. This is one thing we re trying
to understand. If it s not Standard Model-like, it could guide us in trying to understand
how to answer all of these other questions that I mentioned. Anyway, stay tuned. Thanks
very much. (Applause.) SEC. CHU: All right. Thank you very much. And now open it up to
questions. Come forward, there s maybe some remote people also, I think, but any questions?
Q: The gravitational the gravitational field is everybody knows about it. And you can why
is it so difficult to quantize it to have a the properties that of the graviton, that
you do quantize the gravitation field? MR. INCANDELA: You wonder why we can t have a
quantum theory of gravity, you mean? Q: Where does the graviton fit in this in this model
in the Standard Model without MR. INCANDELA: The graviton s not really gravity s not really
in the Standard Model. And string theory s trying to figure that out how to make a quantum
theory of gravity and bring it into a single model. But when we talk about the Standard
Model, we tend to just not even mention gravity because (laughter) s not part of anything
we can really see or detect unless there were very small extra dimensions, as I said. Then
there s a possibility we could detect those. And we have searches at the LHC for those.
We haven t had any sightings. You could that s how you produce miniature black holes, for
example. And we have searches for those. We haven t seen any of those either. SEC. CHU:
Any other questions? That goes back to the thing I mean, our theory of gravity and our
theory of quantum fields it s the rest well, the rest of what we know. And we don t know
anything about their energy. (Laughter.) But the rest of what we know, and we don we have
candidates for dark matter but are in conflict they re not they re not they re not tied in.
Yeah. MR. INCANDELA: Do you have a question? Q: You were showing the values for the decay
by ZZ and et cetera. If those line up, then effectively, a Higgs explains all the different
masses? Is that what it means? MR. INCANDELA: Well, it means we expect the Higgs to decay
oh, I d have to go back quite a ways maybe, I don t know. But I have this plot showing
all the different decay modes. And beginning it here, and you d expect the Higgs well,
it s further back than I thought. It must be the next one here. We think in this region,
at 125, that the Higgs, if it s a this is what you d expect for a Standard Model exactly.
So you pick a mass. The Higgs should only have one mass and there should only be one
type of Higgs and it should decay to all of these different things to bb-bar, these are
quarks, to photons to taus to W s, cc-bar. Photons, by the way m sorry, GG, this is this
is muons and these are the photons. Cc-bar is down here. So we should see a pattern.
We should be able to look for all these things and see a pattern that matches up at one mass.
But it s hard for us to do that. Now, the ones we see the best are the photons and the
Z s. And we ve checked those. And sure enough, they line up. We re at the same mass; we see
excess. But we re seeing more photons than were expected. And that, like I said, is not
significant. If you combine the two experiments it s two point two sigma, something like this.
So it s not huge, but if it sustains if that excess in photons doesn t change by the end
of the year when we have three times more data than what I ve shown here, that becomes
four sigma. And then we have something pretty interesting. SEC. CHU: I think maybe the question
was slightly different because you re talking about the K characteristics and I think maybe
his question and if he didn t ask it, I ll ask it which is which is you know, the mass
of any particle, like the top quark, would depend on the coupling of that particle through
the Higgs field. MR. INCANDELA: That s right. SEC. CHU: And is there a way of predicting
the strength of those couplings? MR. INCANDELA: Is that what you meant? To predict these values
we predict these based on the mass because the Higgs produces I mean, the Higgs engenders
mass, and so we can predict the coupling based on the mass. But we don t have a fundamental
prediction of those couplings, of why those masses are what they are. That s what I said
very early on. SEC. CHU: So the fundamental reason why the top weigh so much has so much
is, OK, using those couples strongly. OK, like the neutrinos, we don t know why, you
know, we can t predict the masses, we can t predict the hierarchy. So as far as I know,
and the high-energy physicist m just the secretary of energy but the high-energy physicist (laughter)
can chime in if I ve said something wrong. MR. INCANDELA: (Inaudible) by the way. (Laughter.)
There is an interesting there are some interesting theories coming out that say that there is
a you know, this kind of idea of a fifth dimension and that the there are these brains that and
what s quite interesting is you find that you can predict these couplings based on the
overlap of the way it functions in this weird space. We ll have to see. Q: So, so far this
looks consistent with the standard model, which you express some disappointment about
sometimes. In refining this and seeing things like branching ratios and so on, what are
the what are the chances are that you will find something inconsistent with the Standard
Model? MR. INCANDELA: You know, we don no, I was saying that right now things are not
very precise. We just reached the point where we know it s there. So that just you know,
at that point, if you just reach five sigma, it s very unlikely you have enough data to
start studying the properties. On the other hand, we have studied them to the extent we
can and there are some inconsistencies. The Higgs to tau tau channel we looked at is zero.
There s no indication of any signal at all. And we come very close to ruling out the standard
model just in that channel alone. The photons, as I mentioned, were too high. There were
too many photons. In fact, we wouldn t have made the discovery as early as we did if the
photons were at the Standard Model level. Remember, we were expecting about three sigma
and both experiments got four to four point five. But it s still low statistics. So the
uncertainty is fairly high. So as I said, for the photons alone, if you combine the
two experiments we re at two point two sigma, something like this, just roughly speaking.
we haven t done this carefully so you shouldn this shouldn t go out to the newspapers and
things. (Laughter.) It probably will, so I m going to get in trouble for that. But it
s around two sigma. With three times the data, you multiple it by, you know, square root
of three, it s 1.7 you get to 3.5 to 4 sigma. Then that s pretty significant. So by the
end of the year re all kind of waiting for the end of the year, it s going to be like
opening Christmas presents, you know? What have we got, you know? We really don t know.
And we will know a lot more, but those results come out in March. Now, we have an intermediate
set of results coming out in November for the Kyoto Conference with double the data,
which will already do something. Then we got to triple. And then we wait because the machine
shuts off for two years to repair so it can go to higher energy. And then we get lots
of data. And we think we can measure all of these things to about 10 percent, maybe even
5 percent, OK, by 2017. It takes us a long time to do these things because this is a
really rare process. So again, this is one in a trillion collisions. And we ve had in
three years about 1,000 trillion collisions. So it took us three years to produce a thousand
of them, of which we can only detect a couple hundred. So it s slow going, but SEC. CHU:
(Inaudible) yes. Q: A question about your early work. Do you see any future for magnetic
monopoles? MR. INCANDELA: Magnetic monopoles? That s a I did this as a graduate student.
It was a candidate event that was so spectacular. Everyone believed that it was there. There
were like 800 theory papers written. I did an experiment with 200 times the surface area
that killed it completely. And then you become famous for, you know, having looked for this
strange particle. Kind of a little wacky thing. We do look for them, actually, at the LHC
in all the accelerator experiments. They take the beam pipes out after they ve been used
and they used and they grind them up and they send them through quantum interference devices
trying to see if there are any trapped monopoles and things like that. But we ve had no evidence
anywhere, unfortunately. (Laughter.) We look for a lot of things that aren t there. SEC.
CHU: Wait, there s a speaker coming to you. Thank you. Q: So the two experiments CMS and
ATLAS are they in any sense complementary as far as the way they do the analysis or
the technique? Or is it pretty much the same method that two different groups are using?
MR. INCANDELA: We re complementary in many ways. The detectors actually use different
technologies but achieve the same more or less the same performance using completely
different technologies. You can different systematic uncertainties, OK. That s one thing.
The analysis techniques are a little bit different as well. On the other hand, as we see each
other present our results, if somebody on the other side had something interesting they
were doing that was very powerful, we ll adapt it and so we adopt it and vice versa. But
there are different people. It s different completely different data, don t forget. So
to some extent they are complementary. But we really need the two to corroborate any
kind of founding this profound, for example. But they re probably I think that s all I
can tell you about it, basically somewhat, yeah. SEC. CHU: OK. I first, just kind of
a comment, fabulous talk; fabulous work. I think the idea of the something this complex
the huge, complex there are things that they did not go into that really push the frontiers
in materials and engineering and electronics and everything. And it was done. And it was
done and it worked. And it s an amazing thing, when you have these really literally 10,000-plus
on both and then you add the accelerators something that complex can actually work.
And the more you get into the details, the more awesome it looks at how can something
so huge, so complex, so complicated actually work. It s an amazing thing. Let me just end
on this note, on Christmas presents and Swiss chocolate. (Laughter.) They got a big Christmas
present a little bit before Christmas. They got what they wanted. But the best Christmas
presents are surprises and the boxes that you know, in a certain sense we want a surprise,
we desperately want to see supersymmetry or something else, because if don t have that,
as clearly explained, we got other questions, other problems that we don t know anything
about. And even if we do get supersymmetry, that s good because then it ll give us another
set of problems that we know nothing about. And so on Swiss chocolate. So you now know
that Swiss chocolate has more energy kilogram for kilogram, pound for pound, than TNT. But
now you will have to ponder this. How can what s the powerful force field that a few
moments on your lips become forever on your hips? (Laughter.) And how what are the forces
that ended up putting depositing that energy there? All right, anyway thank you very much.
(Applause.) (END) gdlR gdlR qeq}q}q}qYq}q}Mq hfl h"@% gdi9: h>fl h\Pv
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