Perfect. Okay, we can see your slides. We can't hear you Daniel.
Can you hear me now? Yes, perfect. Okay, and please go ahead. Thanks. Okay. So yes,
my name is Guerrero. I'm a PhD student at the University of Florida. And I'll
discuss the recent results on expert production using this CMS and ATLAS
detector. So, first, let's start talking about the physics motivation. So after the
discovery of the stellar model Higgs boson measurements of some of its couplings, we
have to answer two questions to answer one of them is, what's the Higgs potential
shape or structure where the Higgs boson coupled to itself or not as predicted in
the standard model? One way to measure it to answer this question questions is by a
measurement of the Higgs stuff coupling lambda here presented in the equation of
the potential. Now we also have a predicted value for for discovery.
In a stellar model using a Higgs boson measurements and measurement of the aspect
of
the value in the off in the vacuum, which gives us around a point 13. Now in the
standard model, the process that has direct access to this coupling is the
Higgs for production. The main production mode is the glue on fusion with a to
amplitude represented here in this slide, where one of them are the one on the left
it has the heats of coupling. Now these two diagrams interfere destructively and
this generator, a small cross section for this process, currently are actor one
femto bomb. And this makes this process very rare and very challenging to see the
LFC however, we can use the same signature now to look for physics beyond the
Standard Model A one way or to do this it's a it's in a production of the
anomalous couplings. They are a modification of stellar Merkel pins, for
instance, in the case of the South cup,
This is parameterised by a modifier this case cup Kappa lambda n or source of a
normal stop this could be the activation of of new vertices associated to new
physics An example is conduct interactions with the three diagrams presented at the
bottom. Now, these anomalous companies can not only enhance their cross sections but
also the mathematics of the process. One example of this is facility the figure on
the right where you can see the spectrum of mass of the Higgs boson pair for three
anomalous couplings. In this case, a couple equals zero that means loss of
coupling in black, a couple of the equal five which is a software spectrum, couple
lambda equal to which, as you can see here in the booth distribution has an
enhancement in a high mass tail. Under a source of new physics is the production of
new resonances. This is predicted in multiple models. An example of this is a
heavier scalar or graph indicating the Higgs boson pair. Now, the period
predict. This restaurant is in a wide range of masses from 250 gb to a few TVs.
Some examples of this theories are MSM inspired models, motors with an extra
singlet or motors will warp extra dimensions. Now let's talk about how, how
do we search for this type of signature in CMS and Atlas, that will depend on the way
that the Higgs boson decays. In this case, so far, let's see, we've proven the five
decades, when we to be the two W's to double leptons. To set both sides are two
gammas, or in this case, two photons. Now, using this final state, we can study a
rich variety of files. These were four data hits for production. Now each of each
of them have a different weight in the spreadsheet fraction, with LED one being
the one with four B's that holds a 33% of the wrenching fraction. Here in this case,
you can see the different different final states with the different branching
factor.
So far in Atlas and CMS, we have investigated seven of them and they are
highlighted here in the gray color and boxes. important to mention that in order
to keep the single yield our rates high, we use the history vdk.
Now, moving to experimental aspects related to this exploration one of them is
the reconstruction of the Higgs to be fair. Now in practice, the way that this
is done is like either with a to a small radius jets or one a large radius jet as
presented in the figure over here. There are different machine learning based
techniques that are using the study of the Higgs to be vdk. In terms of a
identification we have been double v tigers, in terms of their beak, they
address enough of the missing energy caused by similar tonic BDK is where a
neutrino is produced. We have a budget energy question which is multivariate
regression that allow us to correct the budget error
Jeep on it. And this has some implications for instance, in the spectrum of the
digest mass that is a you can see it here at the center of the figure with a
baseline where no correction is applied to the B jets and when up on the spectrum
after we apply this correction in the in the red distribution, and this, this extra
correction allow us to improve the, the the resolution by around 20%. And also
allow us to shift the picture words closer to the Higgs mass. And more important mass
spec expression is a histogram or gamma reconstruction. For this we have in both
experiments a good a gamma energy reconstruction that is translated into an
excellent resolution of the mass into two photons that is currently around, around
1%. An example of this and simulating the best you can see in here when they have
the spectrum of the photon here for heesu gamma gamma the case.
Now let's move to the different
final stages starting with the three that are the most sensitive. Now in this
instance you have the one we did for motor cortex this one holds the largest
branching fraction, but is has an overwhelming amount of multi yet PCD
background. This background is currently modal using data driven methods. Now for
the final analysis, so we have a different observables that could be machine learning
based discriminant, like a boosted decision tree output as presented in here
on the left figure or could be mass based discriminant as the reconstructed mass of
the Higgs boson pairs presented on the fear on the right. This particular channel
is good for studies that high that is mass
and very sensitive channel is the one with two what I'm quite excited to tell leptons
here presented then this one is more or less a compromise between a medium branch
infraction a medium background. Now this is a final set is that is that depending
on the way that he stood out the case, when we require at least one cow has to be
pressing
For final statistical analysis, the discriminant could be for instance, I must
base discriminant as presented on the bottom figure when you have the
reconstructed myself with the heat spare or it could be a machine learning based
discriminant as the BDT score presented on the top figure.
Another important channel is the one way to be sent to gammas presented here, where
this particular channel is characterized by the resonant signature of the of the
signal as it's presented in the bottle figure, and it's presented in a photon
masters spectrum in the red line over here. Now, this one, however,
has a small branching fraction, but at the same time has a small background which
helps in the in the end of for the different analysis performed for the
statistical analysis that it's take advantage of the of the iPhoto mass for
instance, in CMS there is a combined fit between the the photon mass and the mass
of the TV
Now with regards to three analysis that usually are three minute sensitivity, but
there are a nice way to explore and complement these searches is studying from
the one that has to put on words to verbose on. Now this one particular has a
good branching fraction also has a large on irreducible top background. The way
that we explore this channel depends on the way that is better. bosons are decay
in the case of the two simple sentences and started in channels that have to have
two leptons in a final state, in the case of the one with two Ws, this is studying a
single left on on the left on channel. This is presented over here with a with a
searcher that in which is used to discriminate based on the outputs of a
deep neural network. This particular search presented here is the only standard
Memorial search using for round two data. Now that's what regards to events that use
the Higgs to be vdk. So if you don't use it, then you start becoming statistically
limited and what happens with that
The channels ww gamma gamma presented here that is studied in similar tonic WWE case
with discriminant use a fit to the environment of their like photon system.
Finally, the the final channel is one which has four W's. And for the use cases
this is studied in, in multilateral in the multilateral channel, in this case for us
an example show you how it's done the search you have a total of nine
categories, a based on different characteristics of the two laptops or
three left on the far left on categories. And for final discriminate you use our
only accounting experiment
that regardless of a general idea of what is so for each of the final states for
now, let's talk about where where do we stand in the recent searches you see in
round two data, stunning for distant or more production. We know that there's no
quantum channel and well we do actually
To combine multiple channels so that we have a powerful sensitivity. Now, a
summary of this using early data, especially that here on Atlas on the left
are for CMS on the right. So where you can see the different perspective limit of the
production cross section across the different channels under a combination. As
you can observe in each side, you'll see that there are three channels that are
driven this density vt, BB, tau four V, some BB gamma gamma, the best single
channel in atlases BB tau, and the best single channel in CMS is a BB gamma gamma.
After we make this combination, expected a limit of the production cross section we
see that is currently approaching 10 times the standard model prediction
that what what regards or the standard model but now let's move on to the
understanding model search in this case, is a search for anomalous couplings a
couple lambda for this particular
Search, we have already a combination in which we use the most sensitive channels
in this case give us a powerful constraint on couple lambda. Here is a summary, a on
the left for AP class and on the right for CMS.
You have the graph of the limit on the production cross sectional versus say the
Kappa lambda coupling,
you have the combination of the different channels in the black lines. Then, we
compare this expected limit with the expected cross section we can set a
constraint on Kappa lambda that's what it's presented at the bottom for the
observe on this on the spectrum allow Kappa lambda intervals. In the case of
Atlas we have a minus five point A to 12 in the case of CMS yellow intervals from
expected allow the interval is from minus 7.1 to 13.6. Now this is not the only way
to do a constrained couple under very similar way you didn't in the indirect
searches are
Through single Higgs measurements and this is will be addressed by Stefan astok.
Now, that's what regards to non resonant enhancements of new physics. Now let's
let's talk about searches for new resonances in Atlas and CMS is a type of
searches are performed more or less in a model independent search, which you assume
different. Some different spin hypothesis two or zero, a and this is it's been done
a scan in a mass range is starting for two times the Higgs mass three TV. Here in
this slide, you can see there a summary of the expected limit on the production
production versus the mass of this resonance force being zero on the left for
outlets and force being two.
For CMS, this, the searches presented in here were done using around two data and
gave us after the combination the most the strongest constraints that we have early
on.
This type of resonances important to mention there, the different channels
contribute in a more in across the different mass ranges at low mass to be
become a gamma dome, it's it's dominated in medium and high mass range, the four v
channel contributes more to towards the the sensitivity. Now, after the
combination no significant excess of new physics was observed. And then what was
done was to allow us to set certain constraints or parameters. So we
understand moral theories that if you want more information, you can look at this the
additional material.
That's what with regards of the main production model of fusion, we now have a
look of the main production of the secondary production mode that is pectoral
muscle fusion. Now the physics of this production mode, it's it's determined by
this tree diagrams presented here. They important
of the processes that is give us access to the interaction between two vector bosons
and to Higgs bosons through the hh bb quartic coupling which is presented here
in orange. Now, this person is also have an extra handle on on the Higgs coupling
here highlighted in blue on in the second diagram. Now, when we compute the
production cross section, this yield saw for Section 1.73 femto barn which is a
small However, by the presence of new physics through a normal stopping, so, new
resonances this processions can vary and also the kinematics can also be enhanced.
Currently, the the first search was performed using the four B channel. And
you can see here the result of the upper limit on the production cross section
versus the K to be a modifier. In terms of the the expected limit on the standard
approach and cross section for really, it's a bit far from be sensitive and is
currently 140 times the standard model prediction.
That what regards to stellar modeling however, as you can see here in the graph,
currently we would LLC data are able to constrain already is the anomalous HPV
coupling. And in this case, the limit the expected constraint on the modifier t to
be currently ranges from minus six minus point six seven to 3.1. Moreover, this
analysis in the Furby channel also performed a resonant result and if you
want to know more information is in the additional material.
Now, just finally, to summarize the stock I like to say that that his signature a
student lied in, in the battle words, the measure men of the Higgs of coupling then
proven the heat self interaction that will lead to a better understanding of the
electroweak symmetry breaking mechanism. Also, this is shedding light on searches
on for new quarters of the face space for new phenomena. The exploration of the
single
The tour is currently stepping up at elite CES, various final states are already
started deploying powerful techniques for the analysis and the development of the
president the future are vital to search for this elusive signal. Now Karelia in
round two, we already have a spected limit on the two main production modes in of the
standard model for this type signature. So far, using the round two data we have not
observed new physics access and allowed us to constrain and new physics. Now, I also
would like to tell you to stay tuned us lots of results with full round to date
are on their way. This would not be DNS, this is less than 5% of what the LLC will
deliver in the future.
Finally, thank you. Let me know your questions. If you want to discuss more.
There will be a coffee break discussion with somebody that you can follow here in
this life.
Thank you very much Daniel for the for the nice talk.
Look, if anybody has any questions, please feel free to raise your hand. They can
unmute you. Don't be shy.
Okay, Luca.
Please go ahead, Luca. Yes. Can you hear me now? Yes, yes. Yes. Have a question. If
you could comment, for example, on the fact that some channels for the restaurant
searches like BB tau are quite less powerful than in the case of the let's
say, Standard Model signal search.
Yeah, exactly. We've dow seems to be quite powerful in this kind of modern search,
but not so much in the rest of us. Thanks.
Oh, I think my understanding it's that the optimization, what's Donna targeting the
Steiner model point. So in
in general, that put up
Probably the performance in for instance on almost all things on searches for for
for new residences.
Thank you. And we have another question from Catherine. Please go ahead. It wasn't
really a question more following on from the first question. I think the point with
BB tower tower is that it has a sort of sweet spot around sort of four or 500 gV
and which you can see in both cases there and this if you just look at the cross
section limits of the total predicted Standard Model dialog, so you have the two
contributions from the self coupling and then a top leap diagram, then this is
where Mhh peaks. So the way the plot was, if you go back to the,
to the resonant limits,
I can't remember which slide that was.
The way it was divided there low mass was sort of focused about 300 ish and high
mass was considered to be a bit higher than that. And BB tau tau is that that's a
crossover picture. But you can see even in the resonant limits at around four or 500,
Bv towers, that's
okay. Thank you. Do we have any more questions for Daniel?
If not, okay, let's think oh, one second we do.
Please go ahead.
So I was wondering them, I think he was like 717 or 18. So the bound you said on
capital V. is a bound which assumes that everything else is standard model like
Oops, sorry, can you please repeat the question? Because so the bound you said on
Kappa to v? Yes. I assumed that everything is a standard modern like
no, the standard moral like point would be in the middle when we don't currently
don't have a reach in acceptance. That's why the limited it's farther well, so I
mean, all the other parameters, right? Do you have a Kappa lambda? You come you have
a cup of tea? Yeah. The other ones are set to the standard model for them. Okay.
Okay. So it's not, it's not there. marginalized, is basically just an
individual feet to this parameter. Exactly. It's your scan and one of them
have your one sort of fix to this. Okay. Thanks.