Okay, thank you. And I'll present your results on the soft QC and exclusive
processes with nhB. I'll first discuss our results on both ice 10 correlations in
proton proton collisions. Then I'll go over to the measurement of the inelastic
proton proton cross section. And finally, I'll show you results on central x with
production objects I input on proton and in left conditions. So, first going over
to the Bose Einstein correlations. If we have an incoherent source of identical
bosons, then of course, our system needs to be symmetric on the exchange of the
identical bosoms. And what happens then is that different parts of the symmetrized
wave function will interfere constructively and this gives rise to the
Bose Einstein correlation effect. Now to understand a bit better, let's consider
two point sources of items. COBOL zones, let's take same time patterns, then the
two pi n wave function has can be described by the fact that you have
pythons emitted from source alpha detected in detector a with momentum K and pi and
emitted from source beta detected in detector view with momentum kb. And then
of course, you also have the interchange situations where payments are emitted from
source alpha and detected in detector B, and fines are emitted from source beta
detected in detector a. Now, if we assume that we can describe everything by plane
waves, then the amplitude squared of our two pi n system has the form one plus
cosine delta k times delta r where delta k is the difference in momentum between the
two piles and delta r is the distance between the sources. So, our to pine
correlation function will be proportional to one plus cosine delta k times delta r
And this illustrate that the Bose Einstein correlation effect actually measures the
projection of the distance between the two sources on to the difference between the
momenta of the particles. Now, this principle has already been applied in 56
by Henry brown and twist for the measurement of stellar radii. in particle
physics, it has been observed for the first time important antiproton collisions
in 59 already has been seen at Elysee in PPP lead and lead collisions. And it has
also been observed in equals A minus emulation and there are some measurements
in deep inelastic scattering. Now, we can generalize this situation of having to
point sources to a continuous space time distribution of sources. And there the two
kind of two particle correlation function is usually parametrized of the form one
plus lambda times the exponential of minus R times T U where r is the measure for the
size of our source you can think of it as the radius in case of a strictly symmetric
system, Q is a Lorentz invariant, which is a measure for the difference in for
momentum between the two particles and love that is the capacity and it is zero
in case of completely coherent sources when we don't have any Bose Einstein
correlation and love days one in case of completely incoherent sources. Now,
usually, in data, we extract the two particle correlation function by
constructing the ratio of the distribution of two pylons containing the Bose Einstein
correlation effect to a reference sample, which doesn't contain the Bose Einstein
correlation effect. And one way of constructing this reference sample is by
combining two pints from different events. Now, there was a there was always some
imperfections related to this construction of this reference sample and to cancel out
these imperfections, what I usually extract is the double ratio of the two
particle correlation function from data which contains possession correlation
effects, and the top part of the correlation function from simulation which
is free from the Bose Einstein correlation.
Now, we looked at this Bose Einstein correlation as LGB important proton
collisions at the center of mass energy of 70 v we selected same time payments we
transact momentum above hundred annually and through the rapid team between two and
five. We analyzed the bull's eye 10 correlation effect as a function of
charged particle multiplicity. Now, if you want to compare two results from other
experiments, of course, particle ellipticity is not a very practical
quantity. So, instead one construct so called accurate tivity classes, where the
low activity class corresponds to 48% of the event or primary tissues with lowest
multiplicity. Now, we have the medium activity class which corresponds to 37% of
primary vertices with higher multiplicity and then we have the high activity class
which corresponds to 15% of the primary dishes with highest multiplicity. Now,
here you see this double ratio of data to MonteCarlo as a function of q, which is a
measure for difference in for momentum of the two piles. And you see from top to
bottom for low medium and high activity classes. And what you see is that this
double ratio increases at low values of Q and this is a manifestation of the Bose
Einstein correlations. Now, we fit the deserve red data points with the
parameterization I described before and you extracted the parameters are Which is
a measure for the size of your source and love that the county city as a function of
the activity classes, and here you see on the right sorry on the left are and you
see that it increases with increasing particle multiplicity and on the other
hand love that decreases with increasing particle multiplicity. Now, the same trend
has also been observed in other experiments. And in particular, we can
next compare our values for R and lambda with those obtained from Atlas at 70 v.
And in general, the values for R and lambda from A to B are a bit lower than
those from Atlas. And now over to the internet st cross section which is of
course, a fundamental quantity in hedonic interactions, but it's also of importance
for for example, as to particle physics because it enters the description of the
air showers from cosmic rays, and the description of the transport of cosmic ray
particles in the interstellar medium. Now we extracted the inelastic cross section
at LGB important proton collisions at center of mass energy of 13. tv and also
seven TV. And we used an unbiased sample of proton proton collisions. And we only
analyzed the data of the leading bunch in each run in order to avoid background from
pileup, and in total, we collected a luminosity of 10.7 inverse nanobots.
First, we extracted the fiducial inelastic cross section for the cross section in the
acceptance, and we constructed it by looking at the number of events or proton
proton collisions containing at least one front lift a charged particle with
momentum above two GVM. pseudo rapidity between two and five. We, of course,
divided our number of events by our total luminosity, and we multiply it by you,
which is our average number of interactions per event and we corrected
for Background by looking at a bunch of square one of the beams was empty. So, we
obtained a fiducial inelastic cross section of 62.2 million barns with a
systematic uncertainty of Oh point two and a systematic diversity coming from the
luminosity measurement of 2.5 our statistical uncertainties neglige then we
extrapolated our fiducial inelastic cross section to obtain the total inelastic
cross section and we took into account the fractional contribution to the inelastic
cross section of non defective single diffractive and double diffractive
processes, we neglected the interference between these two these three types of
processes and we also neglected the contribution from Central exclusive
production. And then we had to multiply a fractional contribution FX by the fraction
of interactions inside our acceptance for Each of our sub processes and this number
was obtained from a syringe.
I obtained a total inelastic cross section of 75.4 million barn with three Mewbourne
uncertainty coming from the experiment and 4.5 coming from the extrapolation. And
here you see the total inelastic cross section as a function of the center of
mass energy, where the red points are the results from nhB x seven and 13. tv and
you see that our results are in good agreement with Atlas and total. Now, go
over to the exclusive chip side production in ultra peripheral collisions. So, in
ultra peripheral collisions, the beam particles interact at a distance far from
one another. And for the exclusive production of jPi. One of the being
particles emits a real photon this photon splits into a Quark anti quarter. This
work ethic worker interacts with the other being particle to the exchange of to glue
on, and finally the to the park and antique Park combined into Jake sire.
Another problem. And it's interesting to look at these exclusive processes, among
others because they give access to quote to so called generalized partisan
distributions, which are a generalization of the standard PDF. And those generalize
parts and distributions give access to the distribution of partners not only as a
function of their longitudinal momentum fraction x, but also as a function of
their transverse position. Now, let's see where it's high energy. So in other words,
we can reach very low values of exposure. And at these very low values of x, we can
we can approximate the exclusive forces in terms of standard blue on PDF. So by
measuring these exclusive processes, we get access to these standards on PDF and
in addition, the high energy As he puts us, potentially in a region where we could
probe saturation, so the recombination of clothes, neither LGB. Usually when we look
at exclusive chipset production, the jPi is typically reconstructed. So it's DK
into two oppositely charged neurons which are detected in our LCD detector. And
since we are looking at exclusive processes, we of course don't want to
present of any other particles than the two neurons. So ideally, you want to see
large rapidity gaps up to close to the beam line, void of any detector activity.
And the LGB detector itself covers a region in solar activity between two and
five. And our villo tracker provides an additional coverage into the rapidity
between minus 1.5 and minus 3.5. Now this was a situation for one Run one forum to
we install the series of simulators of 200 meters away from the interaction point.
And these simulators allowed us to extend our coverage in rapidity between minus 10
and minus five, and between five and 10. It was really nice to have these detectors
because it allowed us to reduce our systematic uncertainty by 50%. So, coming
to the measurement of exclusive chip site and I will also show you results website
to us. So we looked among others that proton proton collisions at 13 TV, were
both objects I am obsessed with a reconstructed 3d case into neurons are the
nodes of up to the rapidity between two and 4.5. As I already said, We veto any
event where we see additional detector activity, and furthermore, we are required
the value on cancerous momentum squared to be below point at V squared in order to
reduce background in particular coming from proton dissociation. Here you see the
Daniel invariant mass and you clearly see the Jake psi and the smaller site will
speak on top of the continuous Danyoung background that will of course the truck.
You see the cross section differential in rapidity on the left project side on the
right from site to F. And on top of our data points, you see a critical
calculations based on the gloom standard PDFs, you see the calculations at leading
ordering yellow and next to leading order in Yes, we mean it. Okay, and you see that
the next leading order predictions describe for data Well,
now from the job site site twist proton proton cross section, we can extract the
jPi your site twist photo production cross section, you see the foot production cross
section on the left 48 psi and on the right first sight to us as a function of
the photon photon invariant maps, and there should be measurements at 13 TV are
given by the red data points and we see that you see that the rich photon proton
environment mass up to two TV. On top of all the data points from all the
experiments you see also again these theoretical predictions based on standard
un PDF next to leading order given by this dotted line and you see that they describe
the data well. On the other hand, a portal of fit given by the blue curve has
problems to describe the data points at yo and high values of the photon photon
invariant maps. Now, I have a last slide showing you results on exclusive coherent
chips I production in dead lead collisions which gives us access to nuclear PDS or
nuclear generalized part on distributions and potentially also allows us to probe
saturation. So here you see the cross section differential in rapidity. And on
top of our data points, you'll see a whole series of predictions that are either
based on nuclear standard PDF, or on the saturation models. And I'd like to
highlight the model from Auntie Sally at all, which is given by the purple line and
the magenta line, it's based on the saturation model. And in the case of the
purple line, they assume that the distribution is uniform in transverse
positioning see that this doesn't describe our data. On the other hand, as given by
the magenta line, if you take into account the fluctuations of the blue and
distributions as a function of transverse position, you see that the model allows
managers to describe our data well. So in summary, I've shown you that we have clear
signals of Bose Einstein correlations where our results are in agreements with
the other experiments also are in elastic proton proton cross section, extracted
HCBS in agreement with the other energy experiments. And then action your results
on exclusive cheap sigh production important proton collisions, which are
well described by next to leading order standard new on PDF. And then finally,
I've shown you results on coherent exclusive production of jPi in lead, lead.
And here Well, a whole series of models based on saturation and nuclear PDS allows
us proper data. Well so far. Thank you.
Okay, thank you, john, for this very clear token for the perfectly on time to the
second. So is there any question
And in the meantime, maybe I have one myself. If you allow me in SQL yahzee,
things like 10, you have listed a number of processes, which you evaluate which one
of those gives you most of the systematic error when then you make the final
calculation.
I don't know by heart, sorry. Okay, fine.
Okay, if no one raised his hand, I would switch to the second presentation.