Okay, thanks, Sam. So Hi, everybody. So, today I'm going to talk about the victor
was on sketching at high luminosity. Let's see. So
come on.
Okay. So to give you a small introduction first vector was on scattering is the
production of the divers on so as you can see from this Fineman diagram here along
with the two forward jets, and within this blog here, you can have the production via
electric vehicle, or quarter gauge couplings as highlighted in the blue here
in the Fineman diagrams or via the Higgs boson exchange at the tree level as
highlighted in the green in the Fineman diagrams below. So, this process is
interesting because it provides a test of the electroweak symmetry breaking and we
know that it is still to be proven that the presence of The discovered Higgs boson
preserves the unitarity of the longitudinal polarized dives on
scattering. And what this image shows you is the typical BBs topology, with the two
bosons produced centrally and to forward jets with large digest invariant mass and
large data. Gabby alijah it a gap between these two jets for the backgrounds. Strong
plus electronic interaction interactions as shown in the Fineman diagrams here
result in the irreducible background for this process. So, coming to the Heilmann
LSC prospects for these measurements, I will not go through the details of this
roadmap as it was already shown in the previous talk. What's important to take
away from here is that the These projections were done with the assumption
of 200 phyla, center of mass energy or 14 TV and integrated Leumi of up to three at
Oban inverse at high luminosity LSC to of course, cope with the increase Domi
radiation and the pile of challenges posed by the high luminosity LSC both Atlas and
CMS detectors need upgrades. So in the next slide, this slide summarizes briefly
the overview of both Atlas and CMS upgrades. Again, not going into details
what's important for the in the view of the BBs perspective is the extended
coverage of the silicon tracker on the or the inner detector with the Atlas is
extended Ada coverage or the forward chloramine and the forward calorimeter. So
Now coming to the overview of the VBS measurements. This slide shows you the
measurements that have been explored with the high luminosity let's see so far, and
the first three channels hair within the men in this table here with the same same
www z and zz are the analysis that are done with the fully electronic DK modes
via the simulate tonic decay mode was treated separately. And most of these
analysis have been extrapolated from the 13 t v analysis with corrections for cross
sections and parameterised efficiencies using fast simulation or the full detector
simulation. These projections are of course done with the upgraded detector
configurations as shown in the last slide and have been summarized in the yellow
report. For the sake of completeness, I also put a summary of the run to results
in the backup but for the detailed update on run to please see Christians talk on
Thursday. So, before going on to the details of the analysis, few words of the
systematic assumptions that were used for the high luminosity, let's see studies. So
broadly two scenarios were used. One was ran to scenario where the systematics for
a given analysis were taken as it is from the run to and use as it is for high
luminosity galaxy. While there was another scenario referred to as yellow report
scenario, where the theoretical uncertainties were reduced by a factor of
two compared to the current situation and experimental uncertainty These go as one
by square root of l until they hit the detector capabilities of the
Atlas or CMS.
So now, finally coming to the analysis. First, let's start with the same same ww
analysis. So the first goal of the analysis here is to extract the cross
section uncertainty and see how it varies with the luminosity. So to do this board
analysis and CMS in close, use 1d Bank maximum likelihood fit to the invariant
mass distribution as shown here for CMS to extract the uncertainty on the cross
section measurement so what you see on the these two plots, like the middle plot
Right plot the cross section uncertainty as a function of integrated Lumi. For the
systematic assumptions, Atlas uses return to scenario except that the rate
uncertainties on the backgrounds were half vital for the CMS, it is using the yellow
report scenario and in the plots here, you see the uncertainties going beyond 3000
time to bond invoice this is just to show what we can achieve if if we can we try to
combine the results from both CMS and Atlas. So, coming to the next slide and
there and talking about longitudinal scattering measurement from the same sign
ww So, we know that That total BBs cross section can be decomposed into the
polarized components where vo w was on scan longitudinally or transversely
polarized or it can as well be the mixture of longitudinal or data source polarized
component. So, this analysis is challenging because this Ll component is
only about six to 7% of the total VBS cross section, the PT of the jet to be
greater than 50 gb. And to do this measurement, we used delta phi between the
two jets to discriminate between the longitudinal component from the mixture of
the two for both CMS and Atlas, and what is shown is in these two plots delta phi
distribution of the two jets for signal and the big ground, but only in the in the
brain of where the invariant mass between the two jets is greater than 1100 gV. So,
to summarize the desert on this, it was I mean, it was extracted using a
simultaneous fate of to the delta phi distribution that I showed up in the
previous slide and in the Tomas regions of invariant mass of two jets and the
significance that we obtain is shown in the plots below for CMS in Atlas
respectively. And for CMS, we can see that at 3005 to one inverse, we have about 2.7
sigma and if we combine the results from Atlas and CMS, it can Go above three sigma
if you try to combine beyond
to at Oban inverse, but experiment, so, again here one can possibly improve the
results using multi variate based analysis. So, now coming to the WC
analysis here to extract the cross section uncertainty Atlas uses the cut on the dial
in where the invariant mass of two jets at 600 gV or multivariate based analysis
where they I mean where the distribution can be seen from the top right plot for
the signal and the backgrounds. However, CMS uses a two dimensional distribution of
the digit in variant mass in the bins of the digit Angular seven variation and the
result on the cross section uncertainty is shown in the bottom guide plot. And we see
that we have similar same sensitivity also from Atlas at the level of 5%, which is
feasible from both detectors. So, coming to the longitudinal scattering measurement
for this Atlas explore the cost data distribution shown here in the left for
obtaining the significance on the single longitudinal polarization factor fraction
and it was found to be around two to three sigma based on the different selections
that they studied to improve the signal clarity, and CMS used distribution which
is very similar to what I showed here in this slide for distinguishing Between the
LL component and the LL section significance here from CMS is shown in the
right plot and is found to be 1.6 sigma around 3000 to one inverse, again one can
use multivariate analysis to better discriminate against background, which
could possibly improve the results here.
So, now, coming to the Z channel here
this analysis is most challenging because it has height heretical uncertainty based
on the QC these easy process. To deal with this Atlas use three different assumptions
on the systematic biases CMS use both run to and yellow report scenarios with the
additional answer 20 10% on global z, big z big on yield. And Atlas uses this nGj
distribution by CMS uses multivariate analysis to differentiate between the
electroweak and kcd background processes. And when can see that this particular
process can be observed with the significance of about 13 sigma for both
around two or the yellow report scenario. At 3000 femto burn inverse and the
precision we reach to observe the significance describes the process. This
process is about 20% with the 5% theoretical uncertainty that was
considered from Atlas and about 8.5% for right There are four yellow reports in Are
you
at the CMS detector
then what's shown in this right plot is the expected significance of this z
longitudinal affection as a function of Noemi. And we can see again for this
particular process, we have the significance of 1.4 sigma at 3000 frame to
burn inverse for CMS such as tanks and so, coming to the semi electronic decades of
this channel, this analysis is of course different as it deals with diatonic the
case here we have BD DS that are chosen as discriminates to distinguish between the
signal versus the backgrounds and this BD DS are used to extract the results for the
expected significant gains on the Standard Model BBs process and what you see as a
result is shown in the right plot here. And we can see again from here that we
reach about 5.7 sigma at 370 upon inverse, and as far as the cross section
uncertainties are concerned, we reach about 6.5% at 3000 to one inverse. So, to
summarize, measurement on VBS production are presented for phase two Atlas and CMS
detector at high luminosity LLC. We expect expected cross section uncertainties are
at the level of 10% or mostly less than 5%. Also for especially for the same sign
ww or WC analysis for integrating Romeo Juliet Oban inverse and then we also
explored the protec for the potential for establishing the longitudinal vv
scattering and it will be showed that it is still challenging that even with the
combination of Atlas and CMS. It's a very challenging analysis. So we need more
sophisticated analysis and techniques like multivariate
analysis to
do better.
Yeah.
So that's all from my side.
Thank you very much. The floor is open for questions. Please raise your hand if you
have one.
Okay. I don't see a question here.
So was wondering,
on slide 13, but that might be more a question for the Atlas folks here. I see
this PDT distribution and I'm wondering why even for the signal, it's cut off
sharply at 0.6. Something to hear. Do you know why this could be?
I don't know this actually.
It's a good question.
Someone from the audience knows.
Okay. Seems to be a tough question.
We should follow up. So.
So then then I have have another one. And I mean, if you have the results are a bit
different between Atlas and CMS and you said partially, the uncertainty
assumptions are also different and you emphasized a lot That using MBAs might
help. But can we maybe learn anything already from the projections we are
having? We have right now where CMS does better Outlast us better with with similar
and uncertainty assumptions. What's the what is there already a takeaway message
that we can add on top of that?
Well, I mean,
the best I can say is that for the I mean, the uncertainties that we measure,
we could reach
up to the level which is less than 5%.
Okay, for the integrated NUMMI of 3000 came to bond inverse, which is quite good
for observing me on these processes. And for the the longitude nodes, scattering
cross section measurements. I mean, it ultimately will depend on the the various
aspects of the analysis how they take place, but I think I've What I can say is
that it remains very challenging at the end.
Last chance for a question.
All right, I don't see any race tense. So thanks a lot again Sandhya for for this
nice overview
and for answering my my questions.