time. So we'll have four talks, which are all 15 plus three, and then we'll have
approximately 20 minutes of discussion. So our first presentation will be on the
latest experimental results related to initial state physics and that will be
given by a medium. So could you try sharing your site's again?
Okay, so let's see. Is it fine now?
Yes, that's perfect. So I'll take the time and please go ahead when you're ready.
Okay, thank you. So it's my pleasure to speak a second page here and to present to
tell you about latest experimental results related to the to the initial state.
So first, have a quick introduction also since
the first one decision, but so I'll be covering a couple of topics here. So okay,
what we want to do is to characterize the initial state VPN collisions. One thing is
called spatial distributions. So, the geometry of the region in particular to
better test and constrain the global model in particular. So, this is what is
represented and on the right and then of course, another important thing is to
study the momentum distributions and particular the nuclear button distribution
functions. So, what is shown on the right is a platform the PVS 16 paper, so, this
is the ratio of the BDF of Iran in the land close to that of Finnegan and he had
the the best feet and the uncertainties for ek 16 and NCD 15 are shown and also we
can see, maybe I can also introduce the different regions that we that we Discuss
here. So, at Lu x we have the shadowing region where we there is a separation
compared to physicians then under shadowing at intermediate x here and then
at large x we go into the AMC effect and similarly for for quarks and indictments
and yeah just a disclaimer so of course 15 minutes is very short to cover everything.
So, I'm just going to cover kind of best known selection of recent results by just
address and CMS but also covering a bit of Allison Okay, let me start with the
collision geometry and starting with W and z bosons okay. So as we know they are not
expected to be affected or very little by this only interacting GGP and we can use
them to test the initial state geometry. So the global model so here two plus the
four to six To vCenter class results, the one on the left is for W bosons plus or
minus minus and blue and plus in white and then the right plot is for z bosons, we
see that we have indeed what a flat behavior with centrality not perfectly,
but I will mention this in the next slide. And what is also interesting to see here
is that the experimental uncertainties are these for instance, if we can get the W
was on the left this vertical line on the white rectangle and this is smaller than
the normalization uncertainty meaning that and this is also the case for for the
buttons on the right. Only for very for events for simple events, the global is
more precise than the data and that means that we can start you know thinking about
using w z bosons, as a As actually the reference for the other half whoops. So,
instead of having the usual ta for for a, we could start thinking about normalizing
to WSU versions. And then a look more closely at the twins as a function of
centrality. So, Atlas sees this nun perfectly flat trend as it may be
something rising when you go to bury for events. So who once again are in blue and
reds and zebras and some green and they they seem to be slightly rising towards
pay for events Why? The model they plot is just htpc where you try to account for
correlations between the centrality as estimated for what it does and what
happens in the world. We measure we use buttons. And we would expect this kind of
correlations to have the opposite trend. So that is interesting. And I just want to
mention also that next week for the Hopper conference, we have new results from from
CMS that unfortunately, infection at eye control your account to get today. And
also still we have some new results from Alice which are shown here on the right.
It's a bit less precise, but it's a different facility coverage and here also
we see that Okay, there within the uncertainties. There is no very clear
trends, the most beautiful beanies not the IPF, you're still Welcome to this later
but the data seem to agree better than with the calculations which include PDFs.
Okay, so moving to nuclear PDFs. So we're putting the body back on the content of
the initial state. Of course, this is very important because as soon as we do any
constriction or a plant you know, we we need to know when the initial states and
the nature of the internet we will have some correlation between the mutual
kinematics and the x lead. So I have some examples here. The blood on the left is
from the paper from from CMS, the y axis is the X in the LEDs and the x axis 88 of
the pseudo PDT of the moon, the UPS NDK and we see a very clear correlation here.
And the same here in the center for digests, also studying portal equations
where we see that we have this collision between the stability of the de jet and
the x, the ratio of the X in the lead to that of the proton. And then also on the
right we see that by scanning different jet BTS girls Different correlation
between x in the lead on the agent and then also in lead we can add some further
information as we see. I'll start with w presence in potential collisions. So, this
is a recent paper from CMS. Interesting interestingly we see that yeah, this is
what the precise data on the experimental uncertainties are much besides and the
uncertainty events from the from the nuclear PDFs and what is shown here on
this plot is not the usual 90% confidence level then from between we scaled it to
68%. And still the data is greater and more precise. And we see also quite
clearly from from this that the data will not consistent with the prediction from a
three button PDF, which is ct 14 here in red. There is a better agreement with SPS
16 in green, then with entity 15 in orange weather, we'll get conceptions of the left
at the far back about a ratio in the center or the challenge between the right
so, better argument with EPSDT than etech 15. But better get the data if we look at
the if we do a chi square accounting formulations, the data is not completely
inconsistent with NC taxation. And the main difference here we see two in
particular on this book is the the amount of shadowing between these these models. I
mean one of the differences of course, in these companies, we also have some some
new results from from CMS which is study of brilliant production. So, mu plus b
minus production in important equations, not only z bosons but also the virtual
photon continuum from 15 to 600, gv and this is complimentary to with w boson
measurements. The data is up Besides, but we add them as dependents. So we it's kind
of a scan of different scales. And also we add the pity dependents since we have a
final state. So the left plot is the cost section as a function of Damien mess,
where we see this continuum here. And we compared to bootleg so next week in order
predictions, we're done with a free PDF cd 14, or with nuclear modifications to the
PDF CPP f 16. In the center, we have the cross section in the low mass region
between 15 and 60 G. And then on the right, this is the forward backward ratio
for those ms region 60 to 120 G. And there's many, much more to see in these
different
models. Moving to
lead the video on zebras on Cinder. Let's So back to our class as mentioned before,
They mentioned them George W and z bosons in positions, the data seem to be at least
for the normalization to be here better described by ct 14
when you use such 14 rather than using,
yes.
But also in in, in these papers, it's mentioned that the next two next to
anything other effects are important and the effect of normalization. So it's so
big I hear seems that city 14 keeps a bit of prediction with the description. And
also we have this new results from Alice. Were also when we saw maybe a different
bit here, what they see is that the description seems to be better when you
include
nuclear modifications of the PDF, so MPP
16,
let me move to the Jets which I mentioned earlier. So this is a Very good job of
glue and nuclear PDFs of a wide range of, of acts
from shadowing to actually doing an EMC.
So So yeah, if you look at this, but since we have this
anti correlation
between x and theta jitsu, we see on Tasha doing some shadowing and then actually
doing it at midnight PDT and then gets to diabetes, we have to see effect. And it's
worth noting that the data was already included into ebp f 16. Fit. But here, so
there was a previous paper from CMS with only p net but here, this is a p net to PP
ratio. And this is let's sensitive to the modeling of the process in pp. So we
directly see the medications that they give. Again, move now to photons.
Important collisions. So they're also expected to be sensitive to the initial
state i just been in an ETF. So here we see that the main modification with
respect to a flatline to a flat outlet is simply as a spin. So different grouping of
photons to up and down quarks and different mixtures and we have various
tones in the ledgers and the data agree better with the when you pay 16 receipt,
for instance, here in the center, but okay, the consensus orbits model here,
given the composition, and also from CMS, we have a new paper on photon position
pump photon pollution in lead collisions. And, and this is also sensitive to PDFs
though not very sensitive because again, we have we don't expect very large effects
on the job PDFs. And the uncertainties asked to do much better than the previous
results of cosmic maybe not fully precise enough to to see this more nuclear PDF
effects here. Okay, I'll move for the last few minutes to prepare for collisions and
then
the peak meter.
Yes. So, here the idea is to use the lead ions as a source of material photons. And
they can be used as a probe of the political structure and we have some
sensitivity to ups especially for instance with photonic your prediction as the
production site as shown on the right.
Do you have two minutes? Okay.
Just a world first about Graco Yeah,
in photon photon photon lead collisions with some of the synthesis from Allison
LCB. Go here on gypsy in delegations equations and then on the right this is a
coherent epsilon prediction input. equations from CMS and the data are
compared to many different kinds of models with leading all their own excluding other
and different implementations of billing situation. And we see that okay, the data
is already telling us something about these models I mentioned earlier for
nuclear jets. So here is again a sketch of how these are produced. So we're putting
probing gluons in the in the lead nucleus. And the photon lead interactions are
selected using GCC ability gaps. And then the data compared to PCR with a photon
spectrum which is related to predictions from satellite and naturally shown here
but as discussed earlier, we this process is sensitive to nuclear PDFs and just
quickly flash the slide on the clock on the on the heavy flavor which are more
produced in Korean fusion and so we have sensitivity to pure nuclear PDFs and very
small x square, chunky, the precision is quite limited. They have logical sections.
So here I'm interested in many different results from Allison lcV. And the
experimental precision is is is really excellent. The difficulty is to process by
process to to make sure that to study the importance of higher twist or
factorization breaking effects one place where I think it's obvious is here when
compared to FCM say to us up yet so we have PP in for Patel equation says
efficient ability for medics and we see here that a twist is different from GPI
meaning that navely
okay chip say
we have to see if def sec can be included in in PDF IDs Problem site with cannot
because we don't really expect I mean, from the nuclear PDF point of view, we
don't really expect big differences between chips I am say two. So, probably
some other effects are in play for from say twice that may be different from from
Gypsy. But for the other data we see that these are quite precise data and there is
a lot of ongoing discussions from from the service side to see how these data can be
included to counseling therapy. Yes, audience mics and some just in here since
an out of time with a sorority. So, we have really a lot of recent results on
experimental results sensitive to initial state, the uncertainties are getting quite
small and they will get even smaller in the future of course, but we saw also that
depending on the process, the entropy of interpretation Not the wayside for a
while, we have to keep in mind details of patterning, process modeling, geometric
scaling, factorization, breaking effects. Thank you.
Thank you. Thanks so much for this interesting talk, you really covered a
wide range of experimental probes. So we now have just maybe a minute or two we
could take a question. If you have a question, please press the raised hand
button that you have. Okay. I see a question from question.
Yes. So, I mean, can you go to your page two slides, can you I mean, probably not
in question. And can you explain a bit why four w plus w minus a.
Now these suck me next next page sorry, x base on is I have WPS Yes, this one so
left hand so why w plus the b minus they are different. I have different I. Oh,
yes, sorry. So they have different
so I'll try to explain it quick. But
simply because the
the coupling of W buttons to up and down quarks is different, and they also have
different probability distributions. So So that's, that's why and so this ratio of w
plus to w minus is different in the lead to pp. Again, because of I just been
effects, so.
Okay, I see, I would need a sketch.
He does, but in short, this is the reason.
Okay, okay. I see. Okay. Thank you.
Very good. Thanks. So I think that we should move on to the next talk in order
to keep with the agenda, but just a reminder that we will