To the rare processes first innopolis and then we'll go to
Yeah. So Hello, everybody, thank you for being here. And it's pleasure for me to
give you an overview on the latest results from Atlas regarding roto pork production
and yeah, just a bit of context. So, the huge amount of data that we collected
during the run to lead us to test the center model tighter precision, but also
to look so for two very, very tiny signal in basically exploring the right hand, the
right bottom plot, corner of this plot, where top Quark production process, cross
sections are here, and in this talk, I will cover three main analysis. I will fly
over because Carrillo rarely has mentioned a lot of details around the top two gamma
coupling and then CNC and then looking for standard model processes such as these
that qm for tops starting from the first one, so the D three on my CNC coupling
that's what that's because I've lost doesn't have really any latest results
addressing the Standard Model process and therefore, we are looking at the CNC
cabling looking for possible deviation that may come from beyond standard models
scenarios. And the the analysis targets especially the production mode from the
from the left hand diagram in the single top production but also include signals
from from the decay mode and the goal is to estimate EFT operators next lingo to
use D of course with the bosun WB and here right handed and left handed couplings
been treated independently. And the data set has been used is the partial from
2020 15 to 2017 of 2018. One inverse The barn and the selection tends to select
production mode Indeed, we have single top topology in electronic case. So, one
laptop one v jets are required and more than 330 gb of missing dt plus one photon.
And indeed when we look at the production to the, to the decay modes of the
coupling, we can see the need especially in the T q gamma, we have a factor of five
enhancements. When we look at the background, the composition here I will
focus here more on the experimental point of view we see more w plus Jetsons that
was jets event has their useful backgrounds and here we address fitting
generalization in dedicated control region that we can see here. And assuming
generalization here the shapes instead from the Monte Carlo. So, we made them
with the template method but we can see as well that's a gamma feature gamma faces a
large contribution and this is estimated with a data driven decision. Do method we
estimate the to gamma conversion efficiency in both domains in Monte Carlo
and data and then we apply the scale factor to the simulation to have the
prediction and the shape of the prediction is checked in dedicated validation region
where we can see excellent modeling of of the state type of background to be more
sensitive to different coupling also in your network have been trained and used as
a discriminant variable in senior region and for different neural networks have
been trained for all the possible for all the cabling.
Consider so do you gamma, light if the light left and right handed and TC gamma
left and right handed, going to the results very, very brief. We have a
profile on your feet has been done in the country. In the seagull region. Here we
can see an example of two gamma to a left handed scenario. And since we don't see
any deviation from the Standard Model Background we set limits at the 95%
confidence level improving the limit the already existing limits from two times up
to one order of magnitude better. Setting branching limits on the branching ratio
for example, up to the order of 10 to minus five. The limiting factor of the
analysis of course is statistics but also some calibration such as Judge energy
resolution, and gamma scale factor on PT and then modeling of GD bar and single top
that comes into play gamma. fakes go instead into the Standard Model production
mode is processes I will focus in on the tissue production. This is the production
of a single top producer associate with the set bows on him expected to end
predicted by the standard model with a cross section of 102 femto bars at level
of 5% next year in order to CD in a diner Face Face. Official face to face we
developed a muscle by both 30 gV that's very interesting because it's more
sensitive to the desert on the desert cabling because of this very small next to
the encoder using the correction. But it's also sensitive to W that kelvins through
Fineman diagrams such as the one on the right. When we the we use the full brand
new data set with 125 39 inverse femto barn and we selected one top decaying one
top the single top decaying lip tonically clauses that decay lip Donnie Canada as
well. So we expect free lectins in the final Saito's or relapse free leptons in
the final states and in terms of number of jets and V jets. We expect one the Jets
from the top and two and three v jets have been considered because we want to take
into account the curlicue CD radiation as well.
And but the while the B jets is expected to be central from the top, the extra
jetties BK is expected to be so the untag jets as a B jet is expected to be forward.
So, we extended the EDA and accelerate PDD acceptance of 2.4 4.5 the mass of the
electronic mass opposite sign are expected are required to be in desert within that
peak and in the seagull region the violet one, we want the pair to be E or mu mu of
course from the Zed boson while we the same requirements we can set up the
control region containing emu pairs to control this kind of background. But when
we look at the background composition, the most important backgrounds are a TD set in
Diebold simplicity flavor, and therefore, we set it up to call for different for
control region to take into or to control them because that control region at higher
jet multiplicity and to number to be jets, while the bozo dipole zone instead at the
same requirements in terms of jets as the signal region where we bet zero BJ midgets
and we can see that the modeling is quite good for both for both the backgrounds
When we look at the DT bar, let's let's come to this a bit. Tiki Bar Zed cos jets
and also dw can enter the signal region just via fake or non prompt lectins.
studies on the truth level I've seen that most of the contribution come from leptons
from non prompt, non or non prompt leptons from heavy flavor decays. And those are
estimated with the replacement method and normalization of these predictions left
free floating as a free floating parameters in the fit. Here we have, we
can see the control region for the D bar where minimization only is fitted.
Finally, the the discriminant variable need a single region in purple region is
the output of a neural network that has been trained for the signal against the
background, the total background and the most important variables for the training
as we can expect are the mass from the untagged and objects because we expect to
Central forward to apology. They thought they must have the top the reconstructed
top and the suitability of the untagged jets. Finally, the results the fitted
confusional cross region in the same space as the prediction is 94 7% as 997 femto
barn with an accuracy of 13% dominated by statistical uncertainty. There is also
while in agreement with Sundar model within one sigma and the significance over
the background of the signal is above five sigma and we can see as well from the plot
how the, the access is very compatible with these two features. So we can claim
observation of the standard model is a cube reduction. The limiting factors here
are data statistics and concerning the systematics already luminosity intervene
and also and especially modeling of non prompt button backgrounds is quite
important. Going to the latest to the latest analysis I wanted to talk about is
a production of the fourth tops in this system. Model process with a cross section
that is to edit is predicted the next leading order QC D plus electroweak of
correction at 12pm to 120 percent level of accuracy. And this has been very strongly
studied in the past because, yes are many videos under many scenarios predicts
announcement of the cross section for this process, some example are here below. And
the latest as the results combining for possible detection channel. So very
complex combination of analysis using the partial data set of 20 1516 data sets
observed a limit on the Four Tops cross section that is doubled than the expected
so it's worth it for this reason to look at, look at it with the full data to run
two data sets. And that's indeed what we have done looking at it using audio 139%
are born and here we are is not Oh no, we don't consider all the possible detection
channels coming from all the possibilities of the top decay modes, but we specialize
on the same sign the electron in three or more lepton colored so move the electron
channel corresponding to the 12% of the total of the total events. The Moreover,
we were required for six or more jets because the other tops are expected to
decay ironically, and two or more v jets not to decrease too much efficiencies on
the signal. Also in cut on this HD, that is some of the PTO though the objectives
in the final stages are required to be above 500 gV. And we can see from the plot
that this really cut down most of the background while keep a good efficiency on
the signal.
Looking at the background composition here in this region, we can see that the most
important are of course, tGwU that we'll come to this later. And here I want to
focus a bit more on the Freaking nonprofit lepton backgrounds that is very complex
because comes from many different resources such as charging
misidentification, nonprofit leptons from heavy flavor the case, but also conversion
of photons into material or low mass c plus d minus production. And those have
been addressed differently depending on the sources for most of them. So, for the
lessons from the heavy flavor and material conversion and low mass plus minus and
backgrounds, the template method has been has been used. So, MonteCarlo shapes are
assumed and normalization of the backgrounds has been fitted in indicated
control region as we can see just normalization in the control region for
behavioral flavor Latins have been fitted well for the material conversion and low
mass beaker II plus the minus background. The mass of the E pair at primary vertex
has been used because that's sensitive to different sources of the background in
different bits of the distribution. We can see also in this distribution a greenish
contribution is there and this comes from charge misidentification and this is
estimated with a data driven method based on data as the two events. Basically we we
estimated the charge misidentification efficiencies and then we apply that to
opposite sign events to estimate same sign contributions. But the most challenging
part is of course, the estimation or the TT w background in the in our sigma region
and for that, we use the template method we can see a contour region here we can
discuss later if you want about the definition of the country region and with
the chosen good modeling Pacific with the with the background but with the with the
data, but we also check the shapes and the modeling actually of the DW exploiting the
VW charges inventory in invalidation region. So we have the difference between
those In between the number of events we did total lip tonic charge positive and
negative and what is the difference we obtained a very, very pure entity by
entity w region very pure entity W and where we can check the modeling and here
we looked at it and we saw a good a large discrepancy between data MonteCarlo
especially we did with the DW associated with seven or eight jets. And from this
discrepancy, we associated the uncertainty of 154 25 and 300% respectively however,
is excessive we can see in the number of jets doesn't reflect in our BDD score that
we'll come to in the next slides and that is the discriminant variable so and that's
a good news indeed number of jets is not one of the most important variable
instability another answer another sir uncertainty included in the in the fetus
and btw with three and four v jets so associated with Devin farraj we If we
favor jets, and we assume the 50% coming from studies often favor ideation in Tiki
Bar, concerning the signal discrimination ability in our discriminating variable is
the output of BDD that has been trained with
for for the signal to separate with background and for stops in all the
backgrounds have very different topologies. So, we can expect that many
variables are actually important, but the most important one is is the besides game
information. And we can see here the most important variable is the sum over the
tagging score of digits in the events. We can see first a large separation between
shapes that say between the Four Tops and all the background picking into different
places, but also a good modeling of the of this variable. Finally, we we show the
results. So we may To profile likelihood fit in country region, a single region
Sima standardly in a single region, we can see our BTT score in the excellent data to
monta to predict a Monte Carlo agreement after the fit and the normalization
factors are have been fitted coherent as well in the profile it fit as a free 14
parameters for all the backgrounds for you that uses the template method and we can
see for example, their normalization for the material conversion is fitted 1.6 plus
minus 0.5. But very much more importantly a Tw background is fitted to be 1.6 plus
minus 0.3 times the standard error the the cross section, the Standard Model cross
section. And this is indeed very consistent with what has been observed for
example, in detachment 11 is similar, not exactly the same but similar face base.
Finally, coming to the results on in terms of Four Tops Wi Fi signal sent is double
the standard model, the Standard Model value but compatible with the sender model
within 1.7 sigma and a cross section of 24 femto barn with a certainty of 27%
approximately, the observed significance of the background is 4.3 standard
deviation were 2.5 point 2.4 were expected. And when we look at the features
of the data access with respect to the background, we see that the access is very
compatible with four stops feature, features and signature. So, we can claim
finally evidence for for this process. So, conclusions, we shown the latest results
from others in terms of rate of work processes. If mC mC dq gamma coupling has
been studied and best limits have been set concerning operators and renting ratio,
the standard monitors to production has been observed and with a cross section
compatible With the southern model within one sigma and the sun are more and we have
also evidence of the standard model for stops core production with a significance
of 4.3 standard deviation and the cross section compatible with the Standard Model
within one point 70.
And thank you.
Okay, thank you Paulo for this very nice talk. Are there questions for Paulo?
Please raise your hand if you have questions.
Okay, I see for the moment no hands, but I do have a question. At the end, I have
multiple questions, but I will start with the first one. You have shown the T gamma
q in the context of SNC. Did I miss whether you mentioned Do you have also a
cross section extraction from this or a separate analysis?
You mean limits on the FC NC cross For the gamma or
EQ gamma, the Standard Model, cross section mission. Do you have that?
You know, we don't have it's I think it's ongoing effort as far as I know.
There is no public results on it.
Okay, let's see the standard model. Thank you.
I see still no hands, but I saw I have, I will post the second question about the TT
w control region. It looks pretty nice and pure. Can you tell a bit more about the
control region?
How do you select is just the number of jets?
Do you mean the validation or the control region for the Tw backroom?
Actually both looks very pure the maybe the middle plot it's rather
okay. Yeah, this is this is used to check basically the the modeling of the DW.
Apart from the control region that is more closer to To our signal signal region by
the validation region it's made by subtracting the number event of events and
it has the total charge of the electrons of the leptons. So the sum of over over
all the charge the electronic charge positive minus all the the events with the
total electronic charge that is negative. And it's basically discard so the charge
symmetric processes and you get a very purity GW set. This is where we can check
the modeling Yeah.
Okay. So this is sort of background subtracted.
Innocence sense.
Yeah, it's it's basically it comes it comes by by the construction that all the
charge symmetric that is basically very, very similar.
It has basically symmetrical in charge gets gets
discarded from from how the region has been. has been constructed. So yeah.
It's kind of
a way to to to reduce the background in the in the region. Yeah.
Okay. Thank you. Um, so are there other questions for follow?