Yeah,
we can hear you.
Okay, so, um, yeah, so you're a member of the CMS collaboration. And I'm going to be
talking on behalf of both Atlas and CMS, on the production of quarks in association
with a couple of big quarks, WC, and gamma. Which of course, is these processes
are very important for searches for new physics. But as well as important
background for TT h analysis, which is the main topic of this session, so I'm going
to start with the dT by W process. Both collaborations Luca is one fraction of the
data that is 60 Miss titlebar. They focus in single left on triggers, and signal
regions are, are constructed based on the final estates, depending on how many
electrodes we have in the final step. So we focus in the electronic decay of the W
and depending on Common leptons, we have originated from the TPR system, we have
two channels, the same sign, they left on channel and they they try left on Channel
Four these generally generally subdivided in different signal regions as a function
of the sine flavor of the left turn, number of jets and number of digits. So
I'm going to start with the ATLAS experiment, which construct two MBAs. The
fers MBA is constructed to distinguish from leptons from fake leptons, fake
lectures, of course originating from hadron the case gamma conversions or
misidentified jets. The second MBA is designed to suppress misidentified
electron electric charge is only focused on the electron because the Misa the
charge misidentification for meals, it's very, very small, negligible and then
counting regions are constructed to characterize the background. So, the first
control region is the one called charge flip, in which the electric charge is
removed. And, and then these number of events is calibrated from data. So you can
see on the right side top plot, you have the environment of the electron system.
And you can see that is dominated by events originating from charge flips
events. So, you've seen that those events can be calibrated from data. Then the next
control region is about fake leptons. And these analysis use use the matrix methods
are also called tight to loose technique where we look at a sample with a loose
selection of the electron. And you can see on the right side those events from
control region is the meeting at the Kansas City nificant event originating
from events originated from fake letters, okay and additional samples or terminal
samples are produced by different combinations of inverting electron charge,
flavor a number of jets to estimate by one. So, in the case of CMS, the analysis
is very similar to address user BDD but in this case constructed with many variables
excuse me number of jets number of digits HD missing at empty and the angular
separation between the left turn and jet electives are also estimated using the
tight to lose metal but with a small difference. The momentum of the left arm
is corrected and parameterize a function of PD and data that helps to reduce
uncertainties and calibrate in control of these of these events.
Also, data driven nettles are used to estimate the needs identified the electric
charge and the WC events the race is taking from from simulation. So you can
see on the right side distributions for the same side the left on channel. On top
we have the genuine publicity, which you can see the significant violence is coming
from originating from fake leptons. The next one is the charge Miss ID. And the
next one is the WC events. So on the bottom block, you have the output of the
discriminator, the BDT and you can see that in the upper half of the
discriminator is dominated by seeing well it has a large number of single events at
W and in the other half of the discriminator is dominated by migrants. So
these events are divided health goes into the control region and the other health
into the single greater. The next slide, we can see going back to Atlas, the
distributions for the different flavors we have on top the electron. Then in the
middle we have a new and on the right side we have Damion, you can see that when the
electron is present, the charge flips starts those events and starts to appear.
And as I mentioned before, those are calibrated for our control region that you
can see on the bottom plot left side. And in blue, or dark blue, you can see the
fake leptons and also those events are calibrated from data. And you can see one
of those examples of that distribution from the control region on the right side.
So once that is done, then
You can put together along with the other channel that I left on, where church leaps
are no significant, but electrons are still present, then you put all those
samples together into a feed along with a control regions and that is represented on
the bottom plot and you perform a feed and you can extract the TT w cross section,
which Atos reports with a position of 22%. Next slide. So, in the case of CMS, we
look at the BDT distribution. And that is is being divided in in two regions, the
high discriminator value and the low discriminator value and all of that so,
divided as a function of J a number of J's the number of digits and in addition you
can separate it as a function of the sine of the electrons so, you have negative
sign and positive charge and you perform my livelihood feed and you can instruct
the information including the system uncertainties which the leading systematic
uncertainties are originating from the estimation of the fake leptons and also
from the modeling of the of the background, especially volume originated
from the case of dx or dy dx. And that is also another significant contribution
coming from statistics in the control victims. So, CMS also reports with a
similar position that Atlas cross section 40 tw with a precision of 22%. Next slide.
Now I'm moving the DTC channel. Similarly, signal regions are constructed depending
of the number of leptons in the final estate. So in the case that it goes to all
jets, we have the channel opposite signs I left on the next journal will be when the
TTY or ceasing goes to one single laptop final estate does it try left on and then
the next one is the tetra electron channel. Again all these channels are
subdivided with different signal regions to improve the discrimination and have a
better sensitivity on the signal events. These analyses in TDC focus only on the
two channels trial it turns on tetra leptons, because those channels have
higher purity compared with electron. Now the main backgrounds in the case of trial
atom is WC in the case of the tetra electron is cc events. Those can be
calibrated from control regions looking at sidebands for example, looking at evidence
without the Jets failing lectins are estimated something very similar to what
was done for btw and the rest of the process are taking from the simulation. On
the right side, you can see the video discriminator from Atlas on blue is a
signal to DC in the high tail and the dominant bargains are coming from TP VI
and C plus heavy flavor t devices emitted from a control region and the other
vitamins are taken from promote the girl. In the case of CMS, there is a recent
update that includes more data includes also more inclusive leptin triggers and a
modification of the leptin selection using a dedicated MBA, which has a 15% increase
in the efficiency to select leptons on the fake rate is reduced by a factor of two to
four compared with a bigger selection. Next slide. So here we have distributions
from Atlas for the tetra electron channel and the tri Lipton channel on the bottom.
The left on we reconstruct the zz events And we can calibrate that from data. And
similarly in the toilet on we can reconstruct the W z events in sideband
when the electron pair is chosen to be with opposite signs same flavor and know
the tagging requirement, and that those events can be extracted from data and then
calibrated into the scenery. So, then, everything is put together into a feed
here I am bringing back again the TT w because DDC entity Wi Fi together. So,
here are the results from Atlas, where you can see the list of systematic
uncertainties in the case of DPC, the largest uncertainties are originating from
modeling of the background, Monte Carlo and also modeling of the signal you can
see
and you can see The correlation between the two cross sections if you don't,
you'll end up seeing the bottom plot. And the precision measure by address for DDC
processes have about 13%. In the next slide is the results on CMS, which is the
latest result, where more data has been included is a sample of 70 77.5 investment
or in the top plot, you can see the control regions for WC zc and fake
leptons. And in the bottom plot, you can see the summary of the different signal
regions, which are divided as a function of gene multiplicity, number of beat jets
and number of leptons. So the first three blocks is for try left on and the last
block is for the tetra leptin. Remember three try lifting is dominated by fake
leptons and WC events. And in the case of the tetra lepton we have a significant
contribution from Cz events. So God these feet along with nuisance parameters for
the systematic uncertainties which is listed in the next slide. And the largest
uncertainties are originating from the estimation of the lepton id above the 4%
and modeling of the WC and rare bygones T or TTY plus x. So the precision of these
measurement by CMS or DTC is about a percent. That can be compared with a
theoretical prediction that is about the same sensitivity of 9%. The next slide is
a nice summary of these results from Atlas and CMS. For TP W and TTC. So Atlas is in
blue. CMS is in red. The fers ones are 40 tw and the last resource on the on the
plot is for dz so you can see that the only analysis that has higher precision is
the one that is more data of course, which is TTC from CMS, which is 78. It was
petabytes of data.
Everything is consistent with the analog predictions.
So I'm consistent between the two experiment. Next slide. So now, since we
have more events, a more precise analysis in TDC. So CMS went ahead and
additionally, measure the differential cross sections. And that is being done
with respect to electronic observables. Sorry, okay.
I saw that somebody was sending me a chat.
But two minutes.
Wow. Okay. Well, I'm going to speed up then. So these is the results of the
differential correction compared with analog prediction. Using those events, we
can go and search for the physics beyond the standard model using two approaches
the anomalous couplings and the EFT interpretation. So, in the next slide show
the results for the anomalous coupling, those factors are the actual vector on the
left side and the dipole moment on the sorry in the in the right side of that
moment and the actual vector in the left side. What is shown here is the log
likelihood ratio with respect to the base feed value, which is the diamond in blue
and that be compared with the Standard Model prediction the Red Cross which is
only about two sigma off from the standard model. In the next slide is a similar
analysis but using the EFT interpretation where we expand the Lagrangian as a
function of the withdrawal coefficients. And we have four wisdom coefficients that
are relevant for the TTC and on the right side you see the summary of the estimation
of the limits for the for this parameter heaters. Everything is consistent within
the standard model and between the two experiments. So I'm going to move to TD
photon very quickly. These analysis is tricky in the sense that we need to
differentiate very careful, real photons from fake photons. photons originated from
jets misidentified or electrons misidentified as a photons. The cross
section is presented measure measured with respect to a fiducial phase space. CMS has
put yourselves with a TV 22 bytes of data, an atlas with 30 dV in two channels single
leptons and emu channel 140 investment over the next slide is a summary of CMS
results where it performs a likelihood feat and in addition to extracting the
cross section extract the cross section ratio of TT gamma over dt By which are
reducing systematic uncertainties. And these analysis is being updated for 30.
tv, then next analysis is from an address where we have also differential cross
sections of PT gamma as a function of the kinematics of the photon. The most precise
results is from the election channel which uses 140 investment to buy data and and
he's been showing the slide, next slide. So, moving very quickly to the TT levy is
being done by Atlas and CMS in the electron channels one one lepto moto
leptons with high Gen multiplicity. The key here is looking at the betaine
discriminators. And so Atlas is looking at all the bands. CMS is focused in the
additional digits to the TT bar system and then livelihood feeds are constructed and
feed the living system uncertainties are of course be tagging generally the scale
is our FSR and distribution of those discriminators are showing the slide. Next
slide. There is an additional analysis from CMS on TT BB, which uses all jets,
which is interesting is no so sensitive as the other ones but is a nice exercise
where they did construct a good job constructing MBAs to reject QC D control
regions to estimate the background. And the dominant uncertainties are from beet
tagging, the quiet gloom livelihood minimization factorization is scales and
the results are showing this light compared with the predictions. These
results are presenting in different phases spaces. So the definition of the phase of
space are in the bottom plot and the summary is In the next slide, where you
can see in the left side the summary of the results for TPP for CMS and in the
bottom for Atlas. CMS includes leptons budgets, the electrons and the oil jets
sample and you can see, compare it with the Standard Model prediction that they're
all consistent. Similarly, for Atlas Atlas, in addition also present
differential cross sections of GTP be cross section as a function of kinematics
of the other digits. And that brings me to the end, sorry that they have to write in
the last few minutes. I got confused with the time
of the duration of the talk.
Thank you very much. Thanks to you. Any questions for Francesco? You can raise
your hands
Yeah, Francesco.
Hello, Francesco Esperanto again from our plus. I'd like to make a comment on slide
12. Yes, yes. So I think this, this is the CMS blog. Right. And it's correct. Yes. So
it's a CMS blog that illustrates historically what has happened recently.
So it's interesting, surely. One aspect that it's also useful to point out is that
in addition to being pushed, it's your choice to illustrate whatever you want,
and it's very pleasant to see in it and he tried to put things together and also
including the artists contributions, but the course we observe as an incident
storyboard plot. The points are not independent, right? They are correlated,
right? Even that with increasing luminosity. The relevant plots are the one
which have the light in the highest luminosity that I have had independent
results. So, there's basically two TTC results when Atlas one CMS and TT w
result, one Atlas and one CMS. So effectively, just to make sure that we all
pay attention to the labels, not thinking that we have many measurements that are
independent, but effectively that they evolve in time. Right?
Correct. Yes,
definitely is just as crystal, as you say, is a historical review of what was done in
the two experiments. But it should be explained in case that people miss
misunderstand and take these values in a different way.
Okay, is there any other question? I don't, I don't see any hands.
Okay, thank you very much Francesco and we can move on to the second. The second talk
of the session on Tth measurements in Atlas