Good afternoon, everybody, and welcome to this Friday's Physics Colloquium.
It's a great pleasure to introduce, first of all, Gibson from the University of Cambridge today.
So Val is actually a local production is once upon a time a graduate student here dphil in 1986.
So I'd say we both of us remember a time when in the basement of the Venice Room building,
there were things called faxes and terminal rooms and all kinds of strange stuff like that, which has long since disappeared.
Anyway, since. Since, since. Since then. About the first to Sir.
And then in 1989, I think he moved to Cambridge, Missouri, where professor of physics of the in the Cavendish Laboratory.
And she's going to talk to us today about the beauty of flavour, the LHC, the experiment of the Large Hadron Collider.
But thank you, John. Actually, I'm going to tell you about the work of the Oxford Group, the LHC group here,
because any one of them and they're sitting in the audience and they know who they are, could have actually given this talk.
But it's nice to actually come to Oxford because I haven't been here for a long while.
And not only to talk about the beauty of flavour, but also to talk about trying to get more women into physics, which is my other passion.
And I've had a very good conversation with John and the team on that.
So I'm going to tell you about the LHC experiment at the Large Hadron Collider, probably because this is a colloquium.
I should probably give you a little bit of an introduction as far as the physics is concerned.
I'll give you a little bit of an abstract, so to get our minds in order.
This is the standard model of particle physics.
And we have the matter carrying particles, matter particles of the quarks and the leptons, and we have the force carrying particles,
the photon for the electromagnetic force, the glue on for the strong force, and the w inside for the weak force.
And sitting behind all of this is this illustrious Higgs boson, which gives particles their mass.
I'm sure you've seen this before. I just want to say, because we're talking about flavour in this talk, it's just a label.
It's a label that distinguishes between all of these different matter particles, whether they be quarks or whether they be leptons.
But you'll find that in this talk, I'm really just going to concentrate on the Coke flavour physics.
Now, the Higgs boson,
that was a great breakthrough in 2012 with other colleagues from from Oxford have a great deal to do with the discovery of the Higgs boson.
And this is a recent picture form from the Atlas experiment.
And we so we know its mass. We know it's 125, possibly GV and we know it's couplings to to the other particles of the standard model,
although at the moment we don't know the coupling of the Higgs to itself, but you can see it all agrees with what we predict from the standard model.
What is intriguing, however, is the mass of the Higgs boson, and that brings into sort of a the theoretical problem with this,
which is is sort of encompassed within the naturalness hierarchy problem.
And if you were you try and calculate the Higgs mass within the standard model, then this is how you calculate it.
You see, you got to the Bear Higgs mass here and you've got a bunch of constants and then you've got
all of these contributions from the 82 corrections for the other standard model particles.
And you've got this lambda in here, which is the scale up to which the standard model is valid.
Now to explain, the Higgs mass actually requires a fine tuning of these contributions at the level of ten to the -34.
So you can imagine two numbers which agree down to the 34th decimal place.
That's a sort of a naturalness that this means with within with the Higgs mass.
And it also means that the scale to which the standard model is valid is about the TV scale.
This is also known as the hierarchy problem.
And a solution to this is actually to tie the Higgs mass to another symmetry which predicts and protects against these quadratic divergences.
And you can choose your symmetry, which is super symmetry, and there you'll get more.
Higgs is coupling to fermions. You'll get if you put in global symmetry, you get extra dimensions.
Global symmetry, sorry, global symmetries. You get little Higgs technicolour and this is the regime of B beyond the standard model.
Now the LHC, we've been running and we've been searching for beyond the standard model particles.
And you can see just by here for the sort of searches that you look for, for supersymmetry, nothing has been found yet.
Up to about the the TV level. So this is a plot from from Atlas.
And then we have something similar from CMS where they're looking for more exotic particles and indeed nothing new yet has been found.
Now, in naturalness or the naturalness problem, hierarchy problem is not new, but we've seen this actually many years ago and we've seen it further.
John Kwok So in order to explain two effects, one which was the, the interaction between a K0 and a K0 ball,
so the mixing between two flavour I can states and also to explain the particular decay rate.
Then we had to introduce what was called the mechanism and the mechanism if you include that in the standard model,
then in order to to actually pin down the difference between these two, I can states then once again you've got this lambda in here.
So the scale at which the theory is involved, but also you had to include a new particle.
And the prediction in 1970 was that new particle had to have a mass of about 1.2 GV and we now know it as the charm quark.
And that was discovered in 1974 with the discovery of the J PSI, which is direct observation of the charm quark,
which would've been predicted indirectly through this gem mechanism for years previously.
So this is actually the regime, if you like, of quark flavour physics is looking in things like these quantum loops,
if you like to see if you can indirectly observe new physics before you actually observe it directly with direct production of new particles.
Now things have gone on from then. We now know that we've got three generations of quarks and leptons,
and this mechanism has been extended to explain those three generations and their interactions and the interactions between the
quarks of the generations is described by something called the could be Bo Kobayashi Must Go a mixing matrix which is written here.
You see, it's a relationship between weak and states and the mass iron states of the quarks.
Now the c k theory is highly predictive.
It has a huge range of phenomena over a huge, massive energy scale,
and you only need to input full parameters, and we will see those full parameters soon.
It's also hierarchical because the masses have different masses and it's distinctive to the standard model,
so it's not necessarily replicated in other of the theories.
Another important point this second matrix is the only source of matter anti-matter asymmetries in the standard model.
And the matter on some actually symmetries is something which is called which is given by something called CP violation.
Okay. And that's accommodate by one single complex phase in the second matrix.
So beyond the standard model, as I said, standard model is an approximate theory.
A Higgs much like sector is a natural because of this mass of the Higgs, you can't quite understand it,
which is really coming from the energy that you require to produce the Higgs, which we call the vacuum expectation value.
The neutrino mass is not explained in the standard model to many free parameters,
maybe 20 out of 25 parameters of the standard model or in this flavour sector there is no unification of the gauge interactions,
no explain explanation of dark matter, dark energy and we know there must be more CP relation in the beyond the standard model
to explain why we live in a universe which is made of matter and not anti-matter.
Now the core flavour physics probes beyond the LHC energy frontier because you can look in directly in quark loops,
in Quantum Loops, and you can see that the direct search is sort of reaching up to the, the 1tv level.
If you want to put your toes in the water beyond that, then you need to look in directly.
Currently, you need to look in directly with the energies that we're working at to try and find new physics beyond the standard model.
So this is the regime, if you like, of the LHC experiment is we're looking for processes indirectly for new physics.
Now, let me tell you a little bit about the Large Hadron Collider.
As nice as a cartoon sweeping up the Higgs and other matter.
So it started taking data in March 2010.
And I'm sure you've all seen pictures like this before. So there's four experiments around the 27 kilometres of the LHC.
There's the two general purpose experiments, Atlas and CMS.
And then there's a more specific purpose, if you like, experiments at least,
which is looking at gluon plasma, which is another form of matter at the beginning of the universe.
And then there's LHC B, which is doing quark flavour physics.
It is a picture down. The LHC is the magnets that was seen that before.
One key parameter to particle physicists is the luminosity.
And at the LHC we have counter-rotating bunches of protons and each of those bunches is about 10 to 11 protons.
And the rate of events that we get is proportional to, let's say, this luminosity.
Now, that depends on these key parameters. It depends on the circulation frequency.
It depends on the number of protons per bunch, which is probably ten to the 11, the number of punches per B and the beam size itself.
So you quite often hear particle physicists murmuring in the corridors, Ooh, how much integrated luminosity have we got?
Or What's the peak luminosity today? So this defines those terms.
The peak luminosity is our event rate per unit of area.
So it's a centimetre squared. The second. And then we have our integrated luminosity, which is just proportional to the number of collisions.
And so currently we're talking in units of per inverse attempt all.
But the luminosity in LCP is actually tuned, if you like, to produce a sort of a level luminosity all the way through the data taken.
Because what we require is conditions which do not change.
And our event rate, we have so many good events that we can choose what we would like.
So what happens at the LHC? B Interaction point is the the beams are sort of separated vertically and a little bit of tilt on them.
And then as the, the luminosity within the, the beams, the, the interactions itself decreases,
we bring the beams closer and closer together, which means that we have a luminosity which is level.
So it's at this constant level during the the data running.
So our luminosity is different from the luminosity.
If you like, you'll hear Atlas and CMS people talk about.
So this is the story so far for our proton proton collisions.
I'm only going to discuss proton proton collisions.
LCP can take data in proton and and heavy ions like LED collisions or led on like collisions or indeed in a fixed target format.
But today I'm just going to tell you about Proton. Proton. We started running in 2010 and the last round was 2016.
And you can see here where the energy has changed to those running.
So we approximately doubled the energy over the two runs.
So far, the number of punches is increased substantially.
You see, when we were in run one,
we're now doubled the number of punches in the machine and the punch spacing instead of being 50 nanoseconds is 25 nanoseconds now.
That's about seven and a half metres between the punches as they go around the 27 kilometres.
Our peak luminosity stays at about 410 to 32 and then this is our integrated luminosity so far.
So that's the story so far for the schedule. The overall schedule for LHC looks something like this.
So we're with 2006. We just finished 2016 getting ready for the 2017 run.
So we're in the middle of this run too of the LHC.
We then have a brake shutdown where we are going to upgrade the experiment,
which brings us into run three and then with future potential upgrades that will take us all the
way through in the high luminosity running era of the LHC up to 2030 plus plus wherever we end up.
And these are the sorts of integrated luminosity that we would expect our hope to expect in the future.
You can see with our current luminosity, we are way only got a few percent of the data that we would ultimately expect.
So really the key issue, the key message here is the LHC has only just started taking data and that's the case for all of the the LHC experiments.
So this is a picture of the integrated luminosity field for the LHC experiment.
Here we started in 2010 and you can see how much data we've got over these five, six years.
And the last run we're running pretty much we did in run one at the 2012, and we'll start taking data again in March, April time this year.
So at the moment we have a total integrated luminosity of just over five inverse pickup peak.
Sorry, I should've said p couple wrong units.
Let me tell you about the the experiment itself.
We have a huge broad physics program, and it would be absolutely impossible to tell you about everything we did in the time I've got available.
So we can look at CP violation matter, anti-matter asymmetries.
We look at rare decays of particles, we look at QCT, the strong interaction,
do a lot of spectroscopy electroweak we look at the W side and top quarks and also heavy iron, a fixed target type physics as well.
Well, I'm going to do today is really focus on the to be quiet physics physics because this is one of the core physics areas of the experiment.
Now. Why the big clock? Well, it's a third generation clock.
And being in that third generation really means it's intimately linked to CP violation, because that complex phase and the second matrix comes in,
the third generation only comes if you've got three generations of quarks and leptons.
So it's the heaviest clock that forms bound states.
It's mass is about five GV and because it's sitting there in the third generation, it has to decay outside.
It's it's generation to a second or a first generation state.
So that means it's got a long lifetime and it has a lifetime of the order of 1.6 PICOSECONDS Which means if you're going near the speed of light,
the speed of light, you're travelling about a centimetre before you decay.
And that centimetre is crucial to LHC in picking out the clock because it's also got a high mass,
which means there's many accessible final states and also you've got a big production of different sorts of beam particles,
whether that be metals or b baryons that you can look at to to study the sort of physics that we're interested in.
The other thing at the LHC is the main production process is called blue on Blue and fusion,
which means that you produce a B quark and it's anti-matter equivalent.
So you're got a controlled experiment, if you like, of matter and anti-matter produced at the same time.
And these things are correlated. So if the B Corp goes in one direction, the B Bach will go in the same direction as well.
So these are correlated, which that determines what the experiment actually looks like.
And so here it is. This is a schematic of the experiment.
It's a forward so in the forward direction, call it a single arm spectrometer.
It only covers 4% of the solid angle for the interactions, but actually it's got 40% more of the cross-section in there.
It's got excellent tracking precision silicon detector, which is called the Velo.
They've got excellent particle identification. So that means we can really tell when one of these big metals or barrels decays what it's decaying to.
So we know we can pick out what the final state particles are, whether they're piles or count.
And we do that with two ring imaging detectors, and we have an excellent and efficient trigger as well.
So this is a picture of of some of the collaboration and whether Neville's in here must be somewhere.
I was always there. The drink in the button in the back of the in his hand.
So that's a picture of Alex. And you can't really tell what the experiment looks like because you're really looking at scaffolding here.
But at least you get some sense of the size of the experiment.
It's a collaboration of over a thousand members.
773 authors from 69 institutes in 16 countries across the world.
And in the UK we're 11 institutes, so these are the list of them.
And you see Cambridge and Oxford here.
And our main contributions are the very low, the rich computing and the physics, where 18% of the authors are more than 30% of the PhD students.
And so Oxford are the leaders in the rich and the very low and the physics and the computing, of course, because they would do everything.
Okay, this is a nice picture of the the velo detector.
This is half of the velo it's got. What you're seeing here is 21 stations made of silicon detectors separated by three millimetres.
And so there's another half which sort of comes on top of it.
And here it's sitting around the the interaction point. And what's unique about it is when the LHC is running, it's very, very close to the beam.
So it's about eight millimetres from the peak.
When we're setting up and tuning the beams, then we're sitting at about a 30 millimetres 30 centimetres away.
I always love this picture, which is the beam's eye view down our beam pipe.
And this is the aluminium foil which separates the the silicon very low from the beam itself.
So it's in a secondary vacuum and this is in its retracted position.
And when it comes together, it just slightly overlaps. So you don't have any dead that regions.
And the sort of resolution that you get on this millimetre or so sorry, in a centimetre or so that you need to actually detect to get the b,
b, hadrons is 13 microns in the transverse direction and 17 microns, 70 odd microns in the, um, the longitudinal direction.
So this is an excellent, really excellent vertex detector.
And of course, we have the particle ID as well. So the two rich detectors, I don't have time to go into these in detail at all,
but we have two one, which is just before our magnet, which is about the size of a a small car.
And we have one which is after the magnet, which is sort of the size of a double decker bus.
And these two between them give us really good,
efficient particle identification over a large range of momentum from the order of few gbps up to 100 giving.
And I always like this picture that right at the beginning when we started taking data, we took a bit of data with no particle ID information at all,
and then we just applied the rich information and immediately we saw peek of the fly come out.
And that was just with just a very, very little bit of data. And this is what the events look like in the rich detector.
This is a picture of the first big cock event from LHC.
So this is the the full LHC be.
This is where you actually zubin into the halo and you can see all the hits in the very low.
And then this is where the interaction point is. And then if you go even further and start reconstructing and extrapolating the tracks,
you get the primary vertex here and then you get the BTK vertex here.
And this, you can see is of the order of a few a half, a few millimetres, one millimetres.
Okay. So let me get onto the physics. I want to give you a taste of flavour, first of all.
And the first thing I want to do. Well, let me just tell you about a number of publications we've got overall since 2010.
We have approximately 350 papers which have published from the experiment.
59 of them came last year, 16 still in the editorial board, 17 conference notes.
40 analyses are currently under review, so we'd expect another 40 odd papers to come out very, very soon.
So you can see I can only give you a few highlights in the half an hour that I have left.
So I apologise that I if I don't give everybody's favourite analysis as you just coming back to ammonium to the discovery of the J site,
this is where we sat in 1974. So when I was an undergraduate student,
I learned about the JCI and its discovery and I also looked at the GI ammonium spectrum and this is what it looked like pre 2003.
Since then, this picture is totally been revolutionised by several major discoveries and not only from LHC,
but also from the sort of B factories that came before LHC and also from Fermilab and elsewhere.
I'm just and it's not surprising, actually, because if you go back to Mary Girl Mum's original paper,
which is 1964, then if you read this and I'll just zoom in here,
you can see that barrels can now be constructed from quarks by using the combinations of three quartz,
which we all know about, but also five a metals likewise from 2:00 or Quark and Lunch Corp or four.
So even Murray go month in 1964 was predicting the existence of things called tetra quarks and pentaquarks.
And so this is where some of the major discoveries have been made recently in this area.
This is the tetra quarks. So LHC be have been looking at decays like the B minus going to j sci fi and the K minus and this is a three body decay.
And when you have a three body decay, one of the things you can do is is look at a plot, you know, balance, right?
So it's just looking at the kinematics in a three dimensional space and this is the plot for this decay.
Now, if you do a full amplitude analysis and you really have to put all the details into the amplitude analysis,
so you're not only putting the mass of the particles in, but you put in all the decay angles and so on.
Then you realise in order to explain this, this plot, which is a projection of the star plot, so it's the mass of the JSON phi,
then you actually need to include four tetra quarks of two are called X at the moment with this incredible significance.
Eight Sigma. Six Sigma. Six Sigma. Six Sigma. All in one analysis.
So that's petrol quarks and then pentaquarks as well.
And that was looking at the decay of a metal, looking at the decay of a B barium, going to a J so proton can once again look at the phthalates plot.
And you do the full amplitude analysis of that phthalates plot in order to explain its projection in the jet mass of the GE sci fi.
Then the only way you can do it is to include two new particles which are pentaquarks, which are all consistent with Pentaquarks.
And this was recently confirmed with another decay mode. And so this is the sort of pentaquarks.
It's got a CC bar in there and two years in a time clock.
So this picture that we had of shamanism has been totally revolutionised.
This is the current picture. This is the in the neutral case.
Here you can see our conventional status is a J psi, which is what we had before in other conventional states.
We've still got some conventional states which have been unobserved,
but now we have all of these exotic states which are in red that have been either discovered at LHC or previously with the big factories.
And not only do we have neutral harmonium, we now charged harmonium.
And that's got a whole spectrum with it as well.
And here you can see these two Pentaquarks states, which I just showed you.
So this whole QCT picture has now really changed.
And with theorists still trying to explain what these states are.
There's been 300 papers arising from that Pensacola paper.
Just trying to interpret what Pentaquarks are, and there's various interpretations,
if you like, the plain pentaquarks all the way up to try quarks and so on.
Okay. So that's one aspect of the experiment.
And I want to bring you on to looking at matter anti-matter asymmetry, so the CP violation and how the quark flavours mix.
So all of that sea camp theory that I talked about is real.
And there's an awful lot of work that's gone into it over the last 30 years.
And there's many, several people in this audience who have really contribute major to this.
And it's all encapsulated into this thing, which is called, well, this little triangle in the middle is called the unitary triangle.
So these are all the measurements which actually lead up to the the entirety triangle.
It may look a bit like this to those uninitiated, but it actually has got an awful lot of physics in it.
Let me point out a few key things. First of all,
all the measurements that have been made a point pointing towards this apex of
this triangle and the fact that this apex is not zero is the CP violation,
which is in the standard model that gives you the matter. Anti-matter asymmetries.
The area of this triangle actually gives you the amount of CP violation in the standard model.
And so the area is is given here, it's about 310 to the minus five in something called the y'all's code parameter.
And these are the four parameters of the standard.
Elizabeth Various ways of parameters rising, the square matrix.
And this is one by Wolfenstein which has become common use.
And these are the full parameters of the Wolfenstein PARAMETERISATION And this item here,
the fact that that's nonzero, is that where the peak of that triangle is?
So a lot of work has gone into this not only by experimentalists, but also theorists as well,
who've been calculating sort of lattice correct calculations which feed into to all of these measurements.
Now just want to tell you where matter anti-matter asymmetries come from in the standard model
because those who are uninitiated probably don't appreciate where it actually does come from.
So if you consider the decay of a matter particle, I've chosen a B minus here, which has got to be quark in it.
So that's why it's matter and anti-matter, which is a B plus.
It's got an A.P. in it. Then you write down the decay amplitudes which are written here.
The only way that you can get CP violation is if the difference in the rates is not equal to zero.
Now that can only happen if you have two processes which contribute to these decays.
So if we write down these amplitudes and these got two processes,
so this is for the the matter and this is for the anti-matter, then those two processes have a real and imaginary part.
And in here you've got the weak phase, which is part of the second matrix, and you've also got something which explains the strong interaction.
So working out what the difference in rate is, given these amplitudes,
you get a a formula that looks like this and you can only get CP violation if you've got more than one process.
So if you wrote that down just for one process, it would be zero.
You've got to have more than one process and they've got to interfere with different, weak and strong phases.
So that's how you get a difference between matter and anti-matter in the standard model.
So here's an example. This is CP violation in charge PD.
KS and this is the theoretically the cleanest way that you can do it.
You do it with what we call tree decays, where you've just got a line which radiates a W and here we've got B two decay and we've
got two diagrams which contribute one which is favoured where we got a B quark that can go
to a charm quark and one which is suppressed where you've got the B quark skipping a generation
and going to an up quark and skipping the generation brings in a phase called Gamma,
which is the CP phase in the C care matrix, which gives you the CP violation.
Now, if you can reconstruct this in final states, which are identical, then you can start looking at the interference between the two.
And so here you have the matter,
looking at the reconstructed mass of the matter particle when it decays into a particular final state and the antimony particle when it decays into a
particular final state and you can see the heights of these are different and
that's a direct observation of CP violation and matter anti-matter asymmetries.
But ultimately what we want to measure is actually the single gamma.
So that was one example here.
LCB have combined 19 different final states, 71 observables and 32 parameters in this current paper of measurement of combined measurement of gamma.
And you can see that the gamma we measure is 72 degrees with an uncertainty of about seven degrees.
I'm not sort of looking at the scale of new physics of about the five TV region.
Now, if you take this picture of. This universe unitary triangle.
You can see gamma here. That's a shade of brown shaded region.
If I took that measurement away and used all the other measurements to predict what Gamma was,
then you end up with gamma of 65 degrees with an uncertainty about one or three degrees.
Now, any difference between these two would be a direct indication of new physics.
So you can see we're not quite there yet to see a difference. The theoretical uncertainty in all this is incredibly small.
It's ten to the minus two degrees. So with a few more years and getting these measurements down to the order of a degree or so,
then we should be able to see where there's the difference between Measure Gamma in in three processes,
sort of pure standard model processes and other processes which include quantum leaps.
So that's an interesting thing to watch. Now that was charged BS.
Can also look neutral beams, ons and neutral B metals have this special special thing that they actually up just pure quantum mechanics.
I love love it because they just oscillate. They just change their flavour, they change from one to the other.
So you produce a b0 and it will oscillate into a b0 ball through this this diagram here, this box box, loop diagram.
And you can write down the the iron states, the physical iron states in terms of the flavour icon states like this.
So this is just pure trading in equation. There's three main observables in this.
One is the difference in the mass eigen sites or the physical eigen states and the difference in their widths.
But also there's a third observable here, which is the phase difference between the off diagonal elements of the mass and the decay matrix.
This sine 512 here and that's observable is a measure of the probability of a B mass on changing to a people metal compared to a B bar going to be.
So it gives you a difference in matter and anti-matter oscillations, which is in turn CP violation.
So this is the system and this is where you can see the oscillations over a decay time of four picoseconds.
If you work out that distances a couple of centimetres, so a couple of centimetres,
these things oscillate away like crazy with a bell trim, a difference in mass, a beep frequency, if you like, of 17 per picosecond.
That's, that's pure, pure quantum mechanics.
The other thing is you can see CP violation in this mixing.
Now this is actually a plot which I took which is pre LHC.
So before we even started and this is the measure of this third observable and there was great
interest in this before the LHC started because the standard model predictions sat here at zero zero.
And the measurements that were coming from Fermilab at the time were sort of indicating that it was a few sigma away from the standard model.
This is where we are now. So here are the lessons from summer 2016.
Here is the LHC beam measurement. Here are the Fermilab measurements.
Well, something from the big factory here on the beat system. And this is the current world average, which agrees totally with the standard model.
Oh, well, never mind. We went away. There's another one that was this is pre LHC again, which there was indications when you look at the phase here,
which is the B's going to find a state called J sci fi.
This phase is the phase in the decay but takes into account the mixing the mixing phase as well.
And here there was an indication which wasn't very strong, but the few sigma that is the standard model.
And the measurements were indicating that it was a couple of sigma away from the standard model.
We now have we can now zoom in with all the data that we have into this little box.
And this is the current situation where you can see standard multiple prediction
for this phase against Delta Gamma and you can see the combined of LHC B,
which is the Green Atlas and seems to see the zero is bang on the standard model.
So unfortunately, that little anomaly went away as well.
Okay. So it looks like we currently there are no, I think anomalies in the sort of CP violation mixing area in the system.
However, when you get to the rabbis, then we have another picture which is kind of interesting.
We're getting kind of interesting. So let me just tell you, my last 10 minutes about rabbi decays.
Now, Rabbi decays are such because they involve bottom up going to a strange quiet transition.
So be to transition and they're only allowed for via loop diagrams, quantum loop diagrams.
So here's one, for example, for what we call the be going to view plus me minus and here we've got to be a B going to B plus, B minus.
This one's called a penguin diagram because it looks like a penguin, obviously.
So here you can see all of them have loops in them. And in the standard model you can write down in the model independently, if you like,
sort of independent any new physics, an effective Hamiltonian which has constants.
I've got the Fermi coupling constants and the sum matrix elements from the C can make tricks and you can
write it down in terms of some operators and some coefficients which are called Wilson coefficients,
which actually tell you about the short range interactions between the quarks.
So first of all, to me, you know, this is a golden place to look for new physics because you've got a very, very rare process in the standard model.
The branching fractions of the probability that best goes to me plus me minus the branch and fraction is 3.7 times ten to the minus nine.
And for the big D, it's even it's even lower. So just to translate that, if you like,
you would expect the B's to decay into two new ones once every 3.7 billion decays or one every 2 trillion proton proton collisions at the LHC.
It really is the canonical, you know, needle in a haystack, this one.
However, the standard only you can predict this extremely precisely so beyond the standard
model processes can actually cause a measurable effect to the decay rate.
And here are some. Beyond the standard model processes, you can see this x whatever it is, whether it's charge or neutral,
could bring a change to the the the branching ratio, punching fraction.
So after 30 years, we've been looking for peace to me, maybe to me, me.
And then I look back and see them as actually combined forces with all of their data,
both of them individually cross the Four Sigma significance line.
But when they combined, we found that we had combined results to give us a greater than Six Sigma discovery of the best to me,
plus B minus and a greater than three sigma for the BD to me plus minus.
And unfortunately, if it was a couple of weeks, if I was giving this seminar in a couple of weeks time, there would be an update on this.
So keep your eyes and ears open. It would be a nice result.
But this resort in itself, just measuring the branching fractions for bass and being t really does sort of constrain any new physics phase space.
So this is a picture of various supersymmetric models is the standard model.
And if you include those results, then you're sort of looking now down into a box where B on the standard model in supersymmetry might lie.
Of course, there is kind of a way to do things to to change things.
The picture, I guess. Now, let me tell you a little bit about the other rare decay that I was mentioning,
and that is the B to S transition where you've got an L plus minus and the S is contained within a K on or K star.
So it's another powerful approach to to look for new physics.
There's many observables here. An experiment is a very nice thing to look for.
Clean, easy to pick out two leptons on the scale.
And it's also got very keen theoretical predictions, especially at low Q squared is the very mass of the 2 million square.
Now what we're finding here is, first of all, when we look at these processes, the decay rates just seem to be a little bit lower than expected.
We also measure the forward, backward asymmetry. This is a picture of the forward backward asymmetry.
And you can see this is the theoretical prediction and this is the data.
This sort of defines the forward and backward just depends on the orientation of the of the leptons with respect to the scale.
That seems to be slightly different. If you do a global analysis of all the angular observables.
And here's another one, which is anybody in the business will will probably not know what it is,
but it's one of the angular observables everybody always talks about.
You can see that there is a difference between what you measure and what you predict.
And then also there's another bit of information that comes in where you're looking at Lepton universality.
So you're looking at a difference between the decay rate of A B plus going to K plus new plus B minus and a B plus going to K plus E plus E minus.
And in the standard model, that ratio, this thing we call our K should be one.
But you can see the measurement here is significantly less than one at 2.6 sigma.
So there's lots of sort of intriguing anomalies which are coming into the Baby Reddy case.
And so how can you interpret this in any way?
Well, one thing you can do, one thing these people have done is to allow for some new physics in the global fits to the data.
So these coefficients I was talking about with Wilson coefficients, you can just say, okay,
I've got a standard model bit and then I've also got a new physics bit on top of that as well.
So these are two of the coefficients that the coefficients that the most interesting if you like.
Here's the standard model prediction. Here is where all the data is putting its constraints.
And you can see that it's sort of sitting away from the standard model prediction and consistent with this Wilson coefficient,
the c91 being about minus minus one.
So can we interpret that in any way? Well, of course we can.
We can cut it in two ways, if you like.
First of all, if you were to allow a new vector on a Z prime that has the effect in the Z prime would look something like this.
It would couple to the the o'clock be two S and you get the B plus B minus one Z prime.
That would have the effect of just changing the oh nine operator so it would change this Wilson coefficient this C nine and it would shift it to here.
So indirectly, there may be a little bit of indirect evidence for Z Prime.
But of course, we would need to see it directly. It would be fantastic.
Maybe it's out of the reach of the LHC. I don't know.
It depends what its masses. Alternatively a laptop quark.
So this is something which couples two quarks and leptons.
It would contribute equally to the two operators nine and ten contribute.
So you can see here, that's where the prediction would lie.
And if that was the case, if electro quark exists, it would naturally expect you would naturally expect to find flavour of Lepton flavour violation.
So you need to start looking for decays like B plus going to K plus E plus new minus, which clearly we are we are doing.
Anyway. So there's a interpretation of those results that I showed.
But of course, every result has only a couple of sigma.
And as we know from the experience with the CP violation and mixing, quite often a couple of signals go away.
So there's a reason that we wait until things are five or Six Sigma before claiming discoveries.
I know it's the indirect approach of looking, putting your feet in the water to see if there's any new physics outside that.
So just one word on the future for HCB.
This is where a lot of activity is going on now. Run one and run two well underway.
We'd expect to get 18% to bonds by the end of run, too.
So continue the analysis. Lots of results in the pipeline.
We'll update key measurements and get improved precision and push things as far as we can on all aspects of HCB.
The mid-term plan is to upgrade for run three, so run three, we get 25 infrastructure ball.
This is something we were working on very hard right now. It's all been approved and it's happening.
And what we're going to do there is actually replace basically the whole of the redoubtable ACP,
which is because it's limited to one megahertz readout.
We want to read it out of 40 megahertz, which is the crossing rate,
the LHC excellent physics case to to for this to improve the precision an ever increasing broader program of the the experiment and so on.
And this is all going to happen in the the shutdown of 2018 to 20.
Now, I haven't got time to go through exactly what we're going to change,
but basically we're changing majority of electronics and some detector components in order to go for this full 40 mega megahertz readout.
And then fifth, further future.
So more mid term plan is to do a little bit more upgrading for a run for where we should have 50 infrastructure bonds.
So that plan is to consolidate and enhance our current upgraded experiment when it's upgraded to improve the tracking acceptance
for low momentum particles and some replacement of some electromagnetic calorimeter to improve resolutions and so on.
And then the longer term plan, which is very, very interesting at the moment,
lots of discussions going on, what we can do in the fall future for the high luminosity LHC.
Lots going on in Oxford here for the upgrade to the phase two which will come in at five with the target of creating three 300 universe bombs.
So we're currently discussing the feasibility of this major upgrade is challenging because you're going to get thousand 50 events per interaction.
So now we got to look at whether we can use timing information in both our rich detectors,
our particle identity detectors, and also our payload detector in some way.
But it's very compelling.
We haven't reached the theoretical limit, if you like, of of how you can measure all the parameters observable in this field.
And once again, it's a very broad physics program. So this will, if this goes ahead, will take us all the way up to the end of the LHC.
And you see things like this. This is some of the physics I've discussed today.
The the uncertainty on those is just going to go rocket down where we do really get to the
precision that hopefully we might start finding new physics and significant discoveries.
So just to summarise, historically in particle physics, new physics actually first shown up in this sort of indirect method.
If you look at beech decay, the mechanism I've discussed that CP violation, the discovery of the top actually was an.
We knew the mass of the top before it was discovered directly.
We knew that from from the from the said the Higgs.
We had an indication of what the mass of the Higgs was before it was discovered.
So, you know, historically a lot happens in these indirect processes.
LHC B and flow physics really are at this precision frontier.
So hopefully history will repeat itself again very soon.
Thank you. I'll stop there.