# EDS Blois 2017

Europe/Prague
Thakurova 7/2077 166 29 Praha 6 Dejvice <a href="http://www.cvut.cz/en/faculty-of-civil-engineering" target="_blank">Faculty of Civil Engineering, Czech Technical University in Prague</a>
Description

The 17th conference on Elastic and Diffractive scattering, EDS Blois 2017 will be held in Prague, Czech Republic between the 26th of June and the 30th of June, 2017.

The series of International Conferences on Elastic and Diffractive Scattering was founded in 1985 in the picturesque old French town of Blois, famous for its XIV - XVIIth century château, inside of which the first meeting took place. Since then, meetings have been organised every two years in different places of the world: New York (1987), Evanston (1989), Isola d'Elba (1991), Providence (1993), Blois (1995), Seoul (1997), Protvino (1999), Prague (2001), Helsinki (2003), Blois (2005), Hamburg (2007), CERN (2009), Quy Nhon (2011), Saariselkä (2013) and Borgo (2015). The conference will focus on the most recent experimental and theoretical results in particle physics with an emphasis on Quantum Chromodynamics (QCD).

Participants
• Alena Bakalová
• Alexander Kupco
• Alexey Yushkov
• Alice Valkarova
• Anderson Kendi Kohara
• Andre Martin
• Andreas van Hameren
• Anna Cisek
• Antoni Szczurek
• Brian Cole
• Chung-I Tan
• Cyrille Marquet
• Daniel Britzger
• Daniele De Gruttola
• Dmitri Semikoz
• Eva dos Santos
• Francesco Giovanni Celiberto
• Gabor Veres
• Giulia Pancheri
• Ian Balitsky
• István Szanyi
• Ivan Lopez Paz
• Jakub Vícha
• Jan Cepila
• Jan E. Olsson
• Jan Ebr
• Janusz Chwastowski
• Jesus Guillermo Contreras Nuno
• Jiri Prochazka
• Jörg Hörandel
• Karel Cerny
• Krzysztof Kutak
• Lara Lloret
• Lucian Harland-Lang
• Lukas Fiala
• László Jenkovszky
• M. Munir Islam
• Maciej Trzebinski
• Marcin Guzik
• Marek Tasevsky
• Maria Margherita Obertino
• Mario Deile
• Mario Sitta
• Mariola Klusek-Gawenda
• Marta Luszczak
• Marta Ruspa
• Martina Bohacova
• Mateus Broilo
• Michal Deak
• Michal Krelina
• Milos Lokajicek
• Oldrich Kepka
• Oleg Selyugin
• Otto Nachtmann
• Patricia Rebello Teles
• Patrick Kirchgaesser
• Paul Newman
• Petr Travnicek
• Piotr Lebiedowicz
• Qidong Zhou
• Rafal Maciula
• Rafał Staszewski
• Rainer Schicker
• Rajat Gupta
• Richard J. Luddy
• Risto Orava
• Ronan Mcnulty
• Sergey Ostapchenko
• Sofia Andringa
• Stanislav Tokar
• Tamas Csorgo
• Valery Khoze
• Valery Zhukov
• Victor Paulo Barros Goncalves
• Vojtech Kundrat
• William Hanlon
• Wolfgang Schaefer
• Zdenek Hubacek
Support
• Monday, June 26
• Registration
• Organization: Welcome
• 1
EDS 2017 Opening
Speaker: Oldrich Kepka (Acad. of Sciences of the Czech Rep. (CZ))
• Elastic Scattering and Total Cross Section
• 2
Measurements of the total cross section with the ATLAS detector

The total pp cross section is a fundamental property of the strong interaction which can not be calculated in perturbative QCD but only described based on phenomenological models.  The ATLAS collaboration has explored the total proton-proton cross section, using measurements of the total inelastic proton-proton cross sections and of the diffractive part of the inelastic cross section in special data sets taken with low beam currents. The measurements have been performed at center of mass energies of 7 TeV and 13 TeV, using forward scintillators.
The total pp cross section can also be extracted from a measurement of the differential elastic cross section using the optical theorem. The ATLAS Collaboration has performed this measurement in dedicated runs with high beta* optics at 7 and 8 TeV centre-of-mass energy with the ALFA Roman Pot detector. In addition, the nuclear slope of the elastic t-spectrum and the total elastic and inelastic cross sections are determined.

Speaker: Paul Richard Newman (University of Birmingham (GB))
• 3
Elastic and Total Cross-Section Measurements by TOTEM

The TOTEM collaboration at the LHC has completed its analysis of the elastic,
inelastic and total proton-proton cross-sections (via the optical
theorem) at sqrt(s) = 2.74 TeV. The new measurement lies close in energy
to the Tevatron's 1.8 TeV with its two slightly conflicting total
cross-section results.
The presentation will put the new measurement in the context of completed,
ongoing and future measurements at other energies. In particular, preliminary results on the elastic cross-section at sqrt(s) = 13 TeV will be shown.

Speaker: Mario Deile (CERN)
• Coffee Break
• Elastic Scattering and Total Cross Section
• 4
Model independent shape analysis of the differential cross-section of elastic pp scattering

In this work let me review some recent results on the model-independent shape analysis of the differential cross section of elastic proton-proton or proton-antiproton scattering. After a general introduction to the model independent shape analysis of correlation functions in general and functions that are squared moduli of Fourier-transformed amplitude, including Edgeworth, Laguerre, Gauss and Levy expansions [1], I introduce a new expansion technique that is based on the model-independent expansion of the parton-parton forward scattering amplitude in the multiple diffraction theory of elastic scattering [2]. I also discuss an application of these three different levels of the model independent method to elastic pp scattering using TOTEM data at 8 TeV.

Speaker: Tamas Csorgo (Harvard University)
• 5
Elastic pp Scattering at LHC at 13 TeV in the Condensate-Enclosed Chiral-Bag Model of the Proton

Our investigation of high energy pp and p ̅p elastic scattering over the last two decades has
led us to consider that the proton has three regions: i) an outer region consisting of a
quark-antiquark (qq ̅) condensate ground state (also described as quark-antiquark outer
cloud), ii) an inner shell of baryonic charge of size ~0.44 fm, and iii) a core of size ~0.2 fm, where the three valence quarks of a proton with baryonic charges are confined. The proton structure that has emerged leads to four main elastic scattering processes in pp scattering. The first process, which gives rise to diffraction scattering, is due to a glancing collision of the outer cloud of one proton with that of another proton. In a p ̅p glancing collision the corresponding process occurs. The second process involves multiple ω-exchanges. The third process in pp scattering is quark-quark scattering via gluon-gluon interaction. The fourth process – which appears for the first time in our investigation of pp scattering – is a glancing collision at the boundary of a proton with that of the other proton. To describe quantitatively the four processes, their parameters have been determined. For this purpose, we investigated pp 7 TeV dσ⁄dt measured by the TOTEM Collaboration and p ̅p 1.96 TeV dσ⁄dt measured by the D0 Collaboration.

Our calculated pp elastic dσ⁄dt at 13 TeV has no oscillations in the large |t| region, in good agreement with the preliminary TOTEM measurements.

Speaker: Dr Richard Luddy (University of Connecticut)
• 6
High precision description of forward elastic scattering at 8 TeV

The differential cross section in the forward region of
pp elastic scattering at 8 TeV has presented deviation
from pure exponential form. We analyse these data
with attention to the structure of the real part with a
t dependence for the real amplitude motivated by the
study of dispersion relations for slopes. The functional
form obtained is compatible with the existence of a zero
in the forward region. We determine the position of this
zero through the accurate analysis of TOTEM experimental
data at 8 TeV. This zero corresponds to the well known zero
of the Theorem by A. Martin. The characteristic description will
become more evident as the energy increases, such as at 13 TeV.

Speaker: Anderson Kendi Kohara (UFRJ-Brazil)
• 7
Structures in the diffraction cone: the "break" and "dip" in high-energy proton-proton scattering

Anticipating forthcoming publication by the TOTEM collaboration of low-t elastic scattering data at
\sqrt{s}=13 and 2.76 TeV, hereby we emphasize the correlation between two prominent structures
seen upon the otherwise exponential diffraction cone, namely a "break" staying fixed around t=-0.1 GeV^2
and a dip moving with energy logarithmically inwards; while at the ISR the two structures are separated by
a distance of about 1~GeV^2, at the LHC the dip comes close to the periphery of the "break", thus affecting
its parametrization. An unbiased disentangling and identification of the break at the LHC should account for
this correlation.

Speaker: Mr István Szanyi (Uzhgorod National University)
• 12:45 PM
Lunch
• Theory Development in Forward Physics Session
• 8
Problems in Diffractive Scattering

This is a review of recent trends and problems in high-energy diffraction, including elastic and inelastiuc scattering.

• 9
Production of two J/Psi mesons in proton-proton collisions at the LHC

The presentation will be based on our paper in preparation
[1].
We discuss production of pairs of $J/\psi$ quarkonia in
proton-proton collisions in the context of recent results obatained
at the LHC at large transverse momenta.
The leading-order $O(\alpha_s^4)$ contribution
is calculated in both collinear and the $k_t$-factorization approach
with the KMR unintegrated gluon distributions.
We include also two-gluon exchange
contribution which is of the order of $O(\alpha_s^6)$ (not included
routinely in collinear-factorization approach).
This contribution is calculated in the moment only in
the collinear approximation.
In addition we calculate cross sections for
$p p \to \chi_c(J_1) \chi_c(J_2)$.
A feed-down from double $\chi_c$ production to double $J/\psi$
production is estimated for a first time.
The double parton scattering cross section and differential
distributions are calculated using an educated parametrization
of experimental single $J/\psi$ differential distributions in rapidity
and transverse momentum at the LHC energies.
Many differential distributions are calculated.
Results of our calculations are compared with very recent ATLAS data
\cite{ATLAS}.
We find that the two-gluon exchange mechanism and feed down from
double $\chi_c$ production lead to very similar
(in shape) distributions in rapidity distance between the $J/\psi$
mesons as the double-parton scattering approach.
Much larger cross sections are obtained in the $k_t$-factorization approach.
Including the mechanisms leaves much
less room for the double parton scattering contribution which cannot
be calculated from first principle.
The $\sigma_{eff}$ parameter for DPS needed to describe the ATLAS data
is much larger than from previous analyses of double
quarkonium production, where a smaller number of mechanisms was included.
We present distributions in rapidity distance, two $J/\psi$ invariant
mass, azimuthal angle correlations between the two $J/\psi$ mesons
and transverse momentum of the pairs of quarkonia.
In all cases the sum of the four considered contributions reminds
experimental ATLAS distributions [2].

1) A. Cisek, W. Sch\"afer and A. Szczurek, a paper in preparation.

2) ATLAS collaboration,
CERN-EP-2016-211, arXiv:161202950.

Speaker: Antoni Szczurek (Institute of Nuclear Physics)
• 10
Single-diffractive dijet production at high energies within the k_t -factorization approach

We discuss single-diffractive production of dijets at high energies.
For a first time we propose a $k_t$-factorization approach to the diffractive processes [2].
The transverse momentum dependent diffractive parton distributions are obtained from standard (collinear) diffractive parton distributions used in the literature. In this calculation the transverse momentum of the pomeron is neglected with respect to transverse momentum of partons entering the hard process.
The differential cross sections for the diffractive dijets production are calculated in the framework of the $k_t$ -factorization approach based on the resolved pomeron model. Both pomeron flux factors as well as parton distributions in the pomeron are taken from the H1 Collaboration analysis of diffractive structure function and diffractive dijets at HERA.
All leading order processes are taken into consideration
in proton-antiproton collisions at the Tevatron and in proton-proton collisions at the LHC. The extra corrections from subleading reggeon exchanges are also explicitly calculated.
The distributions of the single-diffractive dijet cross section in
normalized average transverse-momentum and normalized average pseudorapidity
are compared with experimental data from the CDF collaboration.
Crucial aspects of possible standard and dedicated measurements within the ATLAS detector are also discussed.

Speaker: Marta Luszczak (University of Rzeszow)
• 11
Helicity in proton-proton elastic scattering and the spin structure of the pomeron

We discuss different models for the spin structure of the nonperturbative
pomeron: scalar, vector, and rank-2 symmetric tensor. The ratio of single-
helicity-flip to helicity-conserving amplitudes in polarised high-energy
proton-proton elastic scattering, known as the complex r5 parameter, is
calculated for these models. We compare our results to experimental data from
the STAR experiment. We show that the spin-0 (scalar) pomeron model is clearly
excluded by the data, while the vector pomeron is inconsistent with the rules
of quantum field theory. The tensor pomeron is found to be perfectly consistent
with the STAR data.

[1] C. Ewerz, P. Lebiedowicz, O. Nachtmann and A. Szczurek,
Helicity in Proton-Proton Elastic Scattering and the Spin Structure
of the Pomeron'',

Speakers: Otto Nachtmann (U), Rainer Schicker (Ruprecht-Karls-Universitaet Heidelberg (DE))
• Coffee Break
• Soft QCD and Soft Diffraction
• 12
Measurements of the particle production properties with the ATLAS detector

A correct modelling of the underlying event in proton-proton collisions is important for the proper simulation of kinematic distributions of high-energy collisions. The ATLAS collaboration extended previous studies at 7 TeV with a leading track or jet or Z boson by a new study at 13 TeV, measuring the number and transverse-momentum sum of charged particles as a function of pseudorapidity and azimuthal angle in dependence of the reconstructed leading track. These measurements are sensitive to the underlying-event as well as the onset of hard emissions. The results are compared to predictions of several MC generators. A similar comparison between measurements and MC generator predictions will be shown, if available, for the strange meson content in top-quark pair events.
Studies of particle correlations in high-energy collisions can provide valuable insights into the detailed understanding of the space-time geometry of the hadronization region. The ATLAS collaboration has studied the momentum difference between pairs of charged particles in data collected at center-of-mass energies of 0.9TeV and 7TeV in view of the presence of Bose-Einstein interference or new models of string fragmentation.

Speaker: Stano Tokar (Comenius University (SK))
• 13
Underlying Event Measurements at the CMS

Measurement of Underlying Event activity performed using proton-proton collision data collected by the CMS detector will be presented. To check the energy dependence of Underlying Event activity, the results are compared with previous measurements from different experiments at different center-of-mass energies.
Speakers

Speaker: Rajat Gupta (Panjab University (IN))
• 14
Soft and diffractive scattering in Herwig

We present a new model for soft interactions in the event-generator Herwig. The model consists of two components. One to model diffractive final states on the basis of the cluster hadronization model and a second component that addresses soft multiple interactions as multiple particle production in multiperipheral kinematics. We present much improved results for minimum-bias measurements at various LHC energies.

Speaker: Mr Patrick Kirchgaesser (Karlsruhe Institute of Technology)
• 15
The LHCf experiment: the very forward neutral particle measurements at LHC

LHC forward (LHCf) is an experiment dedicated to afford the data for verifying and
improving the hadronic interaction models. The LHCf detectors were installed at +/-
140m from the ATLAS interaction point, covered the pesudorapidity range |η|>8.4
including zero degree. LHCf had several operations with different collision energies in p-p and p-Pb collisions.In this talk, we would like to present several recent analysis results. In the operation of √s=13TeV p-p, and √sNN = 5, 8 TeV p-Pb collisions, LHCf had a common data acquisition with ATLAS. The common experiment allows LHCf to classify the collisions into diffraction and non-diffraction at event-by-event basis and test the models with more specific data. Especially, LHCf has unique sensitivities to the low-
mass diffraction, thus it is capable of measuring the low-mass diffraction directly by using ATLAS central information.

Speaker: Qidong Zhou (S)
• 16
Exclusive ρ0 Meson Photoproduction with a Leading Neutron at HERA

A first measurement is presented of exclusive photoproduction of ρ0 mesons associated with leading neutrons at HERA. The data were taken with the H1 detector at a centre-of-mass energy of sqrt(s)=319 GeV and correspond to an integrated luminosity of 1.16 pb−1. The ρ mesons are reconstructed from their decays to charged pions, the neutrons are detected in the Forward Neutron Calorimeter. The photon virtuality is limited to Q²<2 GeV², the total energy of the photon-proton system 20<W<100 GeV and the polar angle of the leading neutron θ<0.75 mrad. The cross section of the reaction γp→ρnπ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering is also extracted. The observed value indicates significant absorptive corrections for the exclusive reaction γp→ρ0+.

Speaker: jan olsson (D)
• Welcome drink
• Tuesday, June 27
• Elastic Scattering and Total Cross Section
• 17
Towards the precision measurements of differential cross sections for elastic pp scattering at the Protvino accelerator.

Elastic-scattering data were analyzed, and it was concluded on the basis of this analysis that precisionmeasurements of differential cross sections for elastic proton–proton scattering at the accelerator of the Logunov Institute for High Energy Physics (LIHEP, Protvino, Russia) over a broad momentum-transfer range are of importance and topical interest. The layout of the respective experimental facility detecting the scattered particle and recoil proton and possessing a high momentum-transfer resolution was examined along with the equipment constituting this facility. The facility in question is able to record up to a billion events of elastic proton–proton scattering per IHEP accelerator run (20 days). Other lines of physics research with this facility are briefly discussed.

Speaker: Dr Vladimir Petrov (Logunov Institute for High Energy Physics)
• 18
Eikonal model analysis of elastic proton-proton collisions at 53 GeV and 8 TeV

Under the influence of standardly used description of Coulomb-hadronic interference proposed by West and Yennie the protons have been interpreted as transparent objects; elastic events have been interpreted as more central than inelastic ones. It is known that using more general eikonal model measured elastic data may be interpreted also very differently; elastic processes being more peripheral than inelastic ones. The most ample elastic data set measured at ISR energy of 52.8 GeV have been recently reanalyzed with the help of the eikonal model and new results obtained. New alternatives of peripheral behavior will be presented and compared to a central one. The impact of recently established electromagnetic form factors on determination of quantities specifying hadron interaction determined from the fits of experimental elastic data will be discussed. The influence of some assumptions on proton characteristics derived from elastic hadronic scattering amplitude determined on the basis of experimental data will be mentioned, too. It concerns mainly the assumed t-dependence of phase of elastic hadronic amplitude. The results will be then compared to similar analysis of experimental data at much higher LHC energy of 8 TeV recently published by TOTEM experiment.

The talk will cover some of the main results obtained and published very recently in:

[1] J. Prochazka, V. Kundrat, Eikonal model analysis of elastic hadron collisions at high energies,
arXiv:1606.09479 (2016); https://arxiv.org/abs/1606.09479

[2] J. Prochazka, M. Lokajicek and V. Kundrat, Dependence of elastic hadron collisions on impact parameter, Eur. Phys. J. Plus (2016) 131: 147; http://link.springer.com/article/10.1140/epjp/i2016-16147-x

[3] TOTEM Collaboration (…,V. Kundrat, M. V. Lokajicek, J. Prochazka,…), Measurement of elastic pp scattering at sqrt(s) = 8 TeV in the Coulomb-nuclear interference region: determination of the rho parameter and the total cross section, Eur. Phys. J. C76 (2016) 661.

Speaker: Jiri Prochazka (Acad. of Sciences of the Czech Rep. (CZ))
• 19
The structure and analytic properties of the scattering amplitude at LHC energies

The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). Based on the analysis of the new LHC experimental data on the elastic proton-proton scattering, which announce the non-exponential behavior of the differential cross sections of the diffraction cone, different model assumptions are examined taking into account the analytical properties of the scattering amplitude.The influence of the different assumptions on the extraction of the parameters of the elastic scattering amplitude, especially on the size of the total cross sections, is examined. The impact of the real part of the scattering amplitude on the behavior of the differential cross sections is analysed in a wide region of the momentum transfer based on the dispersion relations in the local and integral forms. In the framework of the High Energy Generalized Structure (HEGS) model the impact of the unitarization procedure on the form of the diffraction structure in a wide energy region is analysed.
The corresponding functions and the energy dependence of the main parameters of the dip/bum structure of the differential cross sections are obtained. The different models of the hadron structure are analyzed. Their predictions for the elastic scattering differential cross sections are compared with the recent experimental data of the TOTEM and Atlas Collaborations.

Speaker: Oleg Selyugin (JINR)
• 20
Spin Dependence in Proton-Nucleus Elastic Scattering

We study the Coulomb-nuclear interference (CNI), a kinematical region of very low 4-momentum transfer squared, $-t$, where the single-spin asymmetry $A_N(t)$ is measured.
The measurement of the analyzing power $A_N(t)$ offers in particular a way of how polarimeters can determine the beam polarization e.g. in the RHIC spin program.

The current theoretical approaches assume that the proton non-flip to (single) spin-flip ratio, $r_5$, is the same for proton-proton as well as for proton-nucleus collisions.
Unfortunately, this approach is not able to describe newer data on analyzing power for heavy ions, particularly $p-Au$ measurements in the PHENIX experiment.

However, as we demonstrate, $r_5^{pA}$ is subject to strong nuclear effects and considerable differs from $r_5^{pp}$.

This new approach is compared with all available proton-nucleus data for analyzing power including $p-C, p-Al$ and $p-Au$ measurement at different energies.

Speaker: Dr Michal Krelina (Universidad Técnica Federico Santa María)
• Coffee Break
• Hard Diffraction and Central Exclusive Production Session
• 21
Studies of the diffractive photoproduction of isolated photons at HERA

The photoproduction of isolated photons is measured using diffractive events
recorded by the ZEUS detector at HERA. Cross sections are evaluated in the
photon transverse-energy and pseudorapidity ranges $5 < E_T^{\gamma} < 15$ GeV
and $-0.7 < \eta^{\gamma} < 0.9$, inclusively and with a jet with
transverse-energy and pseudorapidity in the ranges $4 < E_T^{\rm jet} < 35$ GeV
and $-1.5 < \eta^{\rm jet} < 1.8$, for an integrated electron-proton luminosity
of 374 ${\rm pb}^{-1}$. A number of kinematic variables are studied and compared
to predictions from the RAPGAP Monte Carlo model. In considering the fraction of
the energy of the colourless (Pomeron'') exchange that is transferred to the
photon--jet final state, $z_P$, it is found that the data lie above the RAPGAP
predictions for $z_P > 0.9$, giving evidence for direct-Pomeron interactions. The
shapes of the kinematic distributions of events below and above this value of
$z_P$ are separately well described by RAPGAP.

Speaker: Leszek Adamczyk (AGH University of Science and Technology (PL))
• 22
Open Charm Production in Diffractive Deep Inelastic Scattering at HERA

Measurements of D(2010) meson production are presented in diffractive deep inelastic scattering (5<Q²<100 GeV²), based on 287 pb−1 of H1 HERA-II data recorded at the centre-of-mass energy sqrt(s)=319 GeV. The event topology is given by ep→eXY, where the system X, containing at least one D meson, is separated from a leading low-mass proton dissociative system Y by a large rapidity gap. The D candidates are reconstructed in the Kππ decay channel. The measured cross sections are compared with next-to-leading order QCD predictions obtained in the massive scheme. The calculations rely on the collinear factorization theorem and are based on diffractive parton densities previously obtained by H1 from fits of the inclusive diffractive cross sections. The measured data are further used to estimate the ratio of diffractive to inclusive open charm production in deep inelastic scattering.

Speaker: Karel Cerny (Charles University)
• 23
Measurement of the cross-section ratio sigma(psi(2S))/sigma(J/psi(1S)) in deep inelastic exclusive ep scattering at HERA

The exclusive deep inelastic electroproduction of psi(2S) and J/\psi(1S)
at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS
detector at HERA in the kinematic range 2 < Q2 < 80 GeV2, 30 < W < 210 GeV
and |t| < 1 GeV2, where Q2 is the photon virtuality, W is the photon--proton
centre-of-mass energy and t is the squared four-momentum transfer at the
proton vertex. The data for 2 < Q2 < 5 GeV2 were taken in the HERA I running
period and correspond to an integrated luminosity of 114 pb-1. The data for
5 < Q2 < 80 GeV2 are from both HERA I and HERA II periods and correspond to
an integrated luminosity of 468 pb-1. The decay modes analysed were mu+ mu-
and J/psi(1S) pi+ pi- for the psi(2S) and mu+ mu- for the J/psi(1S). The
cross-section ratio sigma(psi(2S))/sigma(J/psi(1S)) has been measured as a
function of Q2, W, and t. The results are compared to predictions of
QCD-inspired models of exclusive vector-meson production.

Speaker: Marta Ruspa (Universita e INFN Torino (IT))
• 24
NNLO predictions for dijet production in diffractive DIS

We present the first calculations for dijet production in diffractive deep-inelastic scattering (DIS) at next-to-next-to-leading order accuracy (NNLO). The calculations are based on the antenna subtraction formalism, where the hard coefficients are convoluted with available PDFs for diffractive scattering (DPDFs). Unfortunately, these DPDFs are currently available only in NLO precision.
We outline the methodology of the calculations and compare the new predictions to a variety of observables measured single- and double-differentially at HERA.
The new calculations allow for improved tests of factorisation assumptions in diffractive DIS, tests of DPDFs, and hard QCD studies. In the future, these new calculations will help to constrain the gluon distribution in DPDFs.

Speaker: Daniel Britzger (DESY)
• 25
Rescattering effects in jet–gap–jet processes

The presentation discusses the process of colour-singlet parton–parton scattering, which in hadron–hadron collision can lead to production of jet events, where a rapidity gap is present between the jets. The dynamics of the process is calculated within LL BFKL approximation. Using Pythia 8 MC generator, hadronic shapes of jet–gap–jet events are studied, in particular the distributions of the rapidity gap size resulting from the jet formation processes. In addition, using Pythia's modelling of multiple parton interactions, the rescattering effects are simulated. It is shown how these effects influence the gap size distributions. The kinematic dependence of the gap survival probability is discussed. The talk is based on arXiv:1704.00546.

Speaker: Rafal Staszewski (IFJ PAN Cracow (PL))
• Lunch
• Excursion
• 26
Historic tram ride (departure at 14:30, Lotysska station!)

Lotysska station -> Prazsky hrad station

• 27
Guided walking tour

Approximate route: Prague castle and cathedral, decend to Mala Strana, cross over Charles Bridge to old town, Klementinum Charles university, Old Town Square

• Wednesday, June 28
• Forward physics (Low-x QCD)
• 28
Inclusive dihadron production at the LHC in the NLA BFKL

The inclusive production of a pair of hadrons (a “di-hadron” system), having high transverse momenta and separated by a large interval of rapidity, is investigated. This process has much in common with the widely discussed Mueller-Navelet jet production and can be also used to access the BFKL dynamics at proton colliders. The first full NLA BFKL analysis for cross sections and azimuthal angle correlations for dihadrons produced in the LHC kinematic ranges is presented. It is made use of the Brodsky-Lapage-Mackenzie (BLM) optimization method to set the values of the renormalization scale and study the effect of choosing different values for the factorization scale. The uncertainty coming from the use of different PDF and FF parametrizations is also investigated.

Speaker: Francesco Giovanni Celiberto (Università della Calabria and INFN Cosenza (Italy))
• 29
Photoproduction of J/Psi with dissociation of protons

We present the cross sections for both electromagnetic and diffractive dissociation of protons for semiexclusive production of J/ψ mesons in proton-proton collisions at the LHC.

Differential distributions in missing mass (MX), or single-particle variables related exclusively to the J/ψ meson are calculated for s√ = 7 TeV and 13 TeV.. We compare the distributions for purely electromagnetic and purely diffractive proton excitations/dissociation. We predict cross sections for electromagnetic and diffractive excitations of similar order of magnitude.

The talk is based on

Semiexclusive production of J/ψ
mesons in proton-proton collisions with electromagnetic and diffractive dissociation of one of the protons
Anna Cisek (Rzeszow U.), Wolfgang Schäfer, Antoni Szczurek (Cracow, INP). Nov 24, 2016. 19 pp.
e-Print: arXiv:1611.08210 [hep-ph] | PDF

Speaker: Wolfgang Schaefer (Institute of Nuclear Physics PAN)
• 30
Higher-twist corrections to gluon TMD factorization

I discuss the power corrections to TMD factorization for particle production

Speaker: Ian Balitsky (JLab/ODU)
• 31
Triple-parton scattering effects in D meson production at the LHC

We investigate whether the triple-parton scattering effects can be observed in open charm production in proton-proton collisions at the LHC.
We use so-called factorized Ansatz for calculations of hard multiple-parton interactions. The numerical results for each parton interaction are obtained within the $k_{T}$-factorization approach. Predictions for one, two and three $c\bar c$ pairs production are given for $\sqrt{s}= 7$ TeV and $\sqrt{s}= 13$ TeV. Quite large cross sections, of the order of milibarns, for the triple-parton scattering mechanism are obtained. We suggest a measurement of three $D^{0}$ mesons or three $\bar{D^{0}}$ antimesons by the LHCb collaboration. Confronting our results with recent LHCb experimental data for single and double $D^{0}$ (or $\bar{D^{0}}$) meson production we present our predictions for triple meson final states: $D^{0}D^{0}D^{0}$ or $\bar{D^{0}}\bar{D^{0}}\bar{D^{0}}$. We present cross sections for the LHCb fiducial volume as well as distributions for $D^{0}$ meson transverse momentum and three-$D^{0}$ meson invariant mass. The predicted visible cross sections, including the detector acceptance, hadronization effects and $c \to D^{0}$ branching fraction, is of the order of a few nanobarns. The counting rates including $D^{0} \to K^{-}\pi^{+}$ branching fractions are given for known or expected integrated luminosities. The talk is based on our recent paper [1].

[1] R. Maciula and A. Szczurek, "Can the triple-parton scattering be observed in open charm meson production at the LHC?", arXiv:1703.07163 [hep-ph].

Speaker: Antoni Szczurek (Institute of Nuclear Physics)
• Coffee Break
• Soft QCD and Soft Diffraction
• 32
A lower bound on the pion pion inelastic cross-section

We prove under some "reasonable" assumptions that the pion pion inelastic cross-section is larger than C exp(-C'sqrt{s} ln s)

Speaker: Andre Martin (Unknown)
• 33
Exclusive diffractive production of hadrons in pp collisions

We discuss central exclusive diffractive dihadron production in the reactions $pp \to pp \,\pi^{+} \pi^{-}$, $pp \to pp \,K^{+} K^{-}$ and $pp \to pp \,p \bar{p}$. The calculation is based on a tensor pomeron model and the amplitudes for the processes are formulated in an effective field-theoretic approach [1]. We include a purely diffractive dipion continuum, and the scalar and tensor resonances [2, 3] as well as the photoproduction contributions [4]. The theoretical results are compared with existing STAR, CDF, and CMS experimental data.Predictions for planned or being carried out experiments (ALICE, ATLAS) are presented. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions for outgoing particles.

We discuss the Drell-Hiida-Deck type mechanism with centrally produced $\rho^{0}$ meson associated with a very forward/backward $\pi N$ system [5]. The $pp \to pp \rho^{0} \pi^{0}$ and $pp \to pn \rho^{0} \pi^{+}$ processes constitute an inelastic (non-exclusive) background to the $p p \to p p \rho^0$ reaction in the case when only the centrally produced $\rho^{0}$ meson decaying into $\pi^{+} \pi^{-}$ is measured, the final state protons are not observed, and only rapidity-gap conditions are checked experimentally.

We discuss also the $pp \to pp \pi^{+} \pi^{-} \pi^{+} \pi^{-}$ reaction. Here the $\sigma \sigma$ and $\rho \rho$ contributions [6] as well as the triple Regge exchange mechanism [7] are considered focussing on their specificities. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions. We discuss whether the triple Regge exchange processes could be identified with the existing LHC detectors.

References:
[1] C. Ewerz, M. Maniatis, O. Nachtmann, Annals Phys. 342 (2014) 31;
[2] P. Lebiedowicz, O. Nachtmann, A. Szczurek, Annals Phys. 344 (2014) 301;
[3] P. Lebiedowicz, O. Nachtmann, A. Szczurek, Phys.Rev.D93 (2016) 5, 054015;
[4] P. Lebiedowicz, O. Nachtmann, A. Szczurek, Phys.Rev.D91 (2015) 074023;
[5] P. Lebiedowicz, O. Nachtmann, A. Szczurek, Phys.Rev.D95 (2017) 034036;
[6] P. Lebiedowicz, O. Nachtmann, A. Szczurek, Phys.Rev.D94 (2016) 034017;
[7] R. Kycia, P. Lebiedowicz, A. Szczurek, J. Turnau, arXiv:1702.07572.

Speaker: Dr Piotr Lebiedowicz (Institute of Nuclear Physics Polish Academy of Sciences)
• 34
GenEx - Exclusive Meson Generator

The possibilities of the GenEx Monte Carlo generator will be shown. This tool is being developed by our group and is complementary to the existing MC generators. The generator is self-adapting to the provided matrix element and acceptance cuts. The modular structure of the code, designed for easy process implementation, will be shown. As an example, the exclusive production of pions (continuum plus resonances) will be discussed. This includes predictions for polarised (LHC energies) and non-polarised (RHIC) proton-proton collisions for scalar, vectorial and tensorial Pomeron models.

Speaker: Maciej Trzebinski (Polish Academy of Sciences (PL))
• 35
Survival Probabilites at LHC in mini-jet and other models

Recent results for the total, elastic and inelastic hadronic cross-section from LHC experiments will be compared with predictions from one-channel eikonal mini-jet models, with QCD calculations from Durham and Telaviv groups, and with empirical models based on Regge-type parametrizations, adequately implemented with the very small $|t|$ behavior. The role of soft gluon resummation in the infrared region in taming the rise of mini-jets in their contribution to the increase of the total cross-sections at high energies will be discussed in the context of our proposed BN model. Recent observations such as the edge" and thehollowness " effect in impact-parameter distributions will be discussed and compared with expectations from our model. Survival probabilities at LHC will be estimated and compared with our 2008 results and recent calculations by different authors, which range from circa 10\% to a few permille. We clarify the origin of some such discrepancies.

Speaker: Giulia Pancheri (INFN Frascati)
• 36
Rapidity gap survival in enhanced Pomeron scheme

Rapidity gap survival factors are calculated in the Reggeon Field Theory
framework. In particular, the relative roles of eikonal and non-eikonal
absorptive corrections are investigated. Further, the impact parameter
dependence of rapidity gap suppression is studied, paying a special attention
to the effects of colour fluctuations in protons.

Speaker: Mr Sergey Ostapchenko (FIAS)
• Lunch
• Theory Development in Forward Physics Session
• 37
Holography and Central Production at High Energy

It has been shown that AdS/CFT calculations can reproduce certain
exclusive 2-to- 2 cross sections in QCD at high energy, both for near-
forward and for fixed-angle scattering. We extend prior treatments by
using AdS/CFT to calculate both the exclusive and inclusive central
production cross section in QCD at high center-of- mass energy. We
explore consequence of conformal invariance, and discuss how the
notion of graviton” enters into diffraction scattering, thus providing a
unified framework in interpreting some aspects of high-energy
scattering at LHC.

Speaker: Mr Chung-I Tan (Brown University)
• 38
One-loop amplitudes with an off-shell gluon

Factorization prescriptions that allow for non-vanishing components of
the momenta of initial-state partons require matrix elements with off-shell
partons. It is well known how to define and calculate such matrix elements
at tree-level in a gauge invariant manner. We present the first steps to
arrive at one-loop amplitudes with an off-shell gluon, necessary to reach

Speaker: Andreas van Hameren (IFJ PAN)
• 39
Elastic and inelastic diffraction at the LHC

Diffractive phenomena at the LHC are studied by several collaborations there. In this paper we present our recent results connected with the current and future studies at the LHC, namely the deviation of the exponential behavior in elastic proton-proton scattering at low values of |t| and central exclusive resonance production. Although the above phenomena occur in different kinematical regions, they are related e.g. by Regge-factorization. Deviation from the exponential behavior of the diffraction cone observed near both at the ISR and the
LHC (so-called break) follows from a two-pion loop in the -channel imposed by unitarity. By using a simple Regge-pole model we extrapolate the 'break' from the ISR energy region to that of the LHC. A model for
Pomeron-Pomeron total cross section in the resonance region is also presented.
Central production is treated in a Regge pole including the Pomeron and two different trajectories, as well as an isolated f 0 (500) resonance in the region . A slowly varying background is included. The presented Pomeron-Pomeron cross section is not directly measurable, but is an essential ingredient for calculating exclusive resonance production at the LHC.

Speaker: Laszlo Jenkovszky (Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrologicheskaya str., Kiev, 03680, UKRAINE)
• Coffee Break
• Hard Diffraction and Central Exclusive Production Session
• 40
Central Exclusive Production at LHCb

The cross-section for central exclusive production of J/psi and Psi(2S) mesons at 13 TeV is measured using the LHCb detector. Proton dissociative backgrounds are significant reduced compared to previous measurements through the use of forward shower counters, recently installed for Run 2. Plans for future measurements are also presented to exploit the new Run2 dataset.

Speaker: Ronan Mcnulty (University College Dublin (IE))
• 41
Recent diffractive and exclusive results from CMS

We will present recent results of diffractive and exclusive measurements with the CMS experiment.

Speaker: Patricia Rebello Teles (CBPF - Brazilian Center for Physics Research (BR))
• 42
Measurements of exclusive production with the ATLAS detector

In the absence of forward proton tagging, exclusive processes can be distinguished in the central part of the ATLAS detector exploiting the large rapidity gap in the central region and the absence of charged particles reconstructed in the inner tracking detector. This strategy has been adopted to study the exclusive production of dilepton pairs (ee and mumu) in
proton-proton collision data taken at centre-of-mass energies of 7, 8 and 13 TeV. The results show significant deviations from the pure QED prediction, which can be explained by photon
coherence and proton rescattering effects. If available, a measurement of the production of exclusive pions at 7 TeV with the ATLAS detector will be also presented.
In addition, an analysis performed at 8 TeV concentrates on the electron-muon final state to study the exclusive production of WW boson pairs. This analysis is re-optimised to search for the exclusive production of the Higgs boson in the WW* decay channel and the corresponding results will be discussed.

Speaker: Leszek Adamczyk (AGH University of Science and Technology (PL))
• 43
Results from the combined CMS and TOTEM data taking and high-mass dilepton and diphoton production with the CMS-TOTEM Precision Proton Spectrometer

The measurements of diffractive and exclusive processes in proton-proton collisions at 8 and 13 TeV are presented, covering results of hard single-diffractive and low-mass central diffractive processes. Events are selected by requiring the presence of scattered protons reconstructed in the Roman Pot detectors of the TOTEM experiment. Results from special data taking periods at 8 and 13 TeV with a high-$\beta^{\ast}$ LHC optics configuration and small average number of pile-up events are shown. The data amount to roughly 50~${\rm nb}^{-1}$ at 8 TeV and 400~${\rm nb}^{-1}$ at 13 TeV.

Additionally, the measurements of dilepton and diphoton production in photon-photon fusion with the CMS-TOTEM Precision Proton Spectrometer (CT-PPS) are presented. For the first time, exclusive dilepton production at high masses have been observed in the CMS detector while one or two outgoing protons are measured in CT-PPS using around 10~${\rm fb}^{-1}$ of data accumulated in 2016 during high-luminosity LHC operation. These first results show a good understanding, calibration and alignment of the new CT-PPS detectors installed in 2016. Preliminary results and expectations concerning the search for high-mass exclusive diphoton production are discussed.

Speaker: Lara Lloret Iglesias (LIP Laboratorio de Instrumentacao e Fisica Experimental de Part)
• 44
WE-HERAUS Physics School - Announcement
Speaker: Rainer Schicker (Ruprecht-Karls-Universitaet Heidelberg (DE))
• Conference Dinner - Brevnov Monastery
• 7:00 PM
Organ concert - Church
• 7:30 PM
Aperitive with czech traditional music - Atrium
• 8:00 PM
Conference Dinner - Theresian hall
• Thursday, June 29
• Heavy ions
• 45
Measurements of dijet production in ultra-peripheral Pb+Pb collisions with the ATLAS detector

Beams of relativistic heavy ions are accompanied by a large flux of equivalent photons, and photon-induced reactions are the dominant interaction mechanism in heavy-ion collisions when the colliding nuclei have transverse separation larger that the nuclear diameter. In these ultra-peripheral collisions (UPC) the photon can provide a clean probe of the partonic structure of the nucleus analogous with deep inelastic scattering. This talk presents measurements of dijet production in UPC Pb+Pb collisions performed with the ATLAS detector. Events are selected using requirements on rapidity gaps and forward neutron production to identify the photo-nuclear processes. The relatively clean environment of these events allows for measurements in a region of x and Q^2 where significant nuclear PDF modifications are expected to be present and not strongly constrained by previous measurements.

Speaker: Brian Cole (Columbia University (US))
• 46
Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC

Using the framework that interpolates between the leading power limit of the Color Glass Condensate and the High Energy (or kT) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb-Pb collisions at CM energy 5.1TeV per nucleon pair. The formalism is applicable when the average transverse momentum of the dijet system PT is much bigger than the saturation scale Qs, PT≫Qs, while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to the Weizs\"acker-Williams (WW) unintegrated gluon distribution, which is far less known from experimental data than the most common dipole gluon distribution appearing in inclusive small-x processes. We have calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL+DGLAP evolution equation. The saturation effects are visible but rather weak for realistic pT cut on the dijet system, reaching about 20% with the cut as low as 6GeV. We find that the LO collinear factorization with nuclear leading twist shadowing predicts quite similar effects.

Speaker: Prof. Krzysztof Kutak (IFJ)
• 47
Dijets in heavy ion collisions and the rapidity dependence of the nuclear medium

We use high energy factorisation (HEF) framework, implemented in Monte Carlo generator KaTie, to study forward-central dijets in heavy ion collisions. We argue, that the dijets in HEF allow to study the rapidity dependence of the structure of the fireball formed in the collision.

Speaker: Dr Michal Deak (Institute of Nuclear Physics PAN, Krakow, Poland)
• Coffee Break
• Cosmic Ray Session
• 48
Theoretical status of high energy cosmic rays and neutrinos

In this talk I'll review theoretical models, which explain main high-energy cosmic ray measurements, including spectrum, mass composition, anisotropy, and transition from galactic to extragalactic cosmic rays. Also I'll discuss models, which explain astrophysical neutrinos, recently discovered by IceCube experiment and diffuse gamma-ray background, measured by Fermi LAT.

Speaker: Dmitri Semikoz
• 49
Recent results from the KASCADE-Grande cosmic-ray experiment

High-energy cosmic rays, impinging onto the atmosphere of the Earth, initiate extensive air showers. KASCADE-Grande was recording such air showers over a wide energy range from about 10^5 GeV to almost 10^9 GeV. The properties of cosmic rays have been determined with unprecedented precision and the KASCADE-Grande results have boosted our understanding of the astrophysical origin of cosmic rays. Due to the high detector density and the long exposure time the results are not constraint by the number of air showers recorded. The main uncertainty for the interpretation of the recorded air showers is our incomplete understanding of inelastic hadronic interactions at high energies, in particular in the kinematic forward region. The air-shower data are used to set constraints on hadronic interaction models. Recent results will be presented.

Speaker: Jörg Hörandel (Radboud University Nijmegen)
• 50
Fixed target results from LHCb for cosmic rays physics

The LHCb experiment has the unique possibility to measure interaction
of a few TeV protons with different gas targets, such as He, Ne,
Ar, and Xe. Excellent particle identification in the 10-100 GeV/c
momentum range allows to measure exclusive particle production at an
energy of sqrt(sNN) ~ 100 GeV in the forward direction at 2<eta<5.
The reported measurements of antiproton production in p-He, and
charm production in p-Ar collisions are the first results in the
series of such measurements. While the measured antiproton cross section
significantly constraints the existing calculations of the cosmic
rays fluxes that are relevant for the space-born experiments, the
open charm production can be usde to improve the prediction for
atmospheric neutrino in the IceCube experiment.

Speaker: Dr Valery Zhukov (Rheinisch-Westfaelische Tech. Hoch. (DE))
• 51
Soft Particle Production in Cosmic Ray Showers

Indications of a discrepancy between simulations and data on the number of muons in cosmic ray showers exist over a large span of energies. We focus on the excess of multi-muon bundles observed by the DELPHI detector at LEP and on the excess in the muon number in general reported by the Pierre Auger Observatory. Even though the primary CR energies relevant for these experiments differ by orders of magnitude, we can find a single mechanism which can simultaneously increase predicted muon counts for both, while not violating constraints from accelerators or from the longitudinal shower development as observed by the Pierre Auger Observatory. We present a brief motivation and describe a practical implementation of such a model, based on the addition of soft particles to interactions above a chosen energy threshold. Results of an extensive set of simulations show the behavior of this model in various parts of a simplified parameter space.

Speaker: Jan Ebr (Institute of Physics, Prague)
• Lunch
• Forward physics (Low-x QCD)
• 52
The tensor pomeron and low x DIS

The tensor-pomeron model is applied to low x deep-inelastic lepton-nucleon
scattering (DIS). In addition to the soft tensor pomeron, which has proven
quite successful for the description of soft hadronic high-energy reactions,
we consider a hard tensor pomeron. The combination of these two pomeron
exchanges and the f2 reggeon exchange allows a description of the absorption
cross sections of real and virtual photons on the proton in the same
framework. A detailed comparison of the model with the latest HERA data is

Speakers: Otto Nachtmann (U), Rainer Schicker (Ruprecht-Karls-Universitaet Heidelberg (DE))
• 53
Inclusive production of vector quarkonia at the LHC

We discuse prompt production of $J/\psi$ mesons in proton-proton collisions at the LHC within NRQCD $k_{t}$ factorization approach using Kimber-Martin-Ryskin (KMR) and Kutak-Stasto (KS) unintegrated gluon distribution (UGDF). We include both direct color-singlet production ($gg \to J/\psi g$) as well as a feed-down from $\chi_{c} \to J/\psi \gamma$ and $\psi' \to J/\psi X$. The corresponding matrix elements for $gg \to J/\psi$, $gg \to \psi'$ and $gg \to \chi_{c}$ include parameters of the nonrelativistic space wave functions of the quarkonia at r=0, which are taken from potential models from the literature. We calculate the ratio of the corresponding cross sections for $\chi_{c2}/\chi_{c1}$. We compare our results with ATLAS experimental data. Differential distributions in rapidity and transverse momentum of $J/\psi$ and $\psi'$ are calculated and compared to experimental data of the ALICE and LHCb collaborations. We will present results for three different values of energy 2.76 TeV, 7 TeV and 13 TeV.

Speaker: Anna Cisek (University of Rzeszow)
• 54
Effects of parton shower dynamics on PDF evolution

We present results from a parton branching solution of the DGLAP equation which includes the transverse momentum distributions for all parton flavours.
The resulting parton distributions are confronted with semi-analytical DGLAP solution as well as with distributions obtained by Pythia parton-shower machinery.
In this way we test the consistency between Monte Carlo parton-showers and the PDFs based on collinear DGLAP evolution.

Speaker: Radek Zlebcik (Deutsches Elektronen-Synchrotron (DE))
• 55
Associated production of D mesons with one and two jets at the LHC

We have studied production of open charm mesons in association with one or two jets at the LHC.
The cross sections for $c\bar{c}+\mathrm{jet}$ and $c\bar{c}+\mathrm{2jets}$ final states production
are calculated in the leading-order collinear approximation as well as in the $k_{T}$-factorization
approach, where a part of higher order corrections is effectively included.

Both processes under consideration here give possibilities of detailed testing of pQCD dynamics beyond
standard case of inclusive charm cross section. This opens new ways, e.g. for phenomenological verification
of different models of transverse-momentum-dependent (unintegrated) parton distribution functions in the case
of mulit-particle final states. For the case of $c\bar{c}+\mathrm{jet}$ mechanism, different unintegrated gluon
distribution functions are used in the $k_{T}$-factorization approach. Several predictions for the LHC are presented,
including various correlation observables. Integrated cross sections for $D^{0}+\mathrm{jet}$ production for ATLAS
detector acceptance and for different cuts on jet transverse momenta are also presented [1].

Associated production of charm with two jets is also very interesting from the point of view of searching for
multiple-parton interaction effects. We have carefully examined production of $D^{0}+\mathrm{2jets}$ and
$D^{0}\bar{D^{0}}+\mathrm{2jets}$ in both single-parton scatttering (SPS) and double-parton scattering (DPS) mechanisms.
For both final states we indicate regions of phase-space where the DPS contributions clearly dominate over the standard
SPS components. Several correlation distributions useful for measuremt of the DPS effects for the LHCb experiment are proposed [2].

[1] R. Maciula, and A. Szczurek, "Charm quark and meson production in association with single-jet at the LHC", Phys. Rev. D94, 114037 (2016).

[2] R. Maciula, and A. Szczurek, a paper in preparation.

Speaker: Rafal Maciula (Institute of Nuclear Physics PAN)
• Coffee Break
• Hard Diffraction and Central Exclusive Production Session
• 56
Photon-Photon physics at the LHC

I discuss the possibilities for using the LHC as a photon-photon
collider.I demonstrate that the photon parton
density in the proton is currently quite well known and consider the
implications for the LHC phenomenology. In addition, the colour
singlet nature of the photon means that it can readily lead to
exclusive or semi-exclusive events, with limited or no extra particle
production in the final state. I show how such exclusive
processes, in particular in combination with proton tagging
measurements, provide an excellent environment in which to test
the Standard Model and search for the BSM physics.

Speaker: Prof. Valery Khoze (IPPP, Durham University,UK)
• 57
Prospects for gamma gamma -> Higgs and gamma gamma -> WW measurements at the Future Circular Collider

We present the possibilities for the measurement of two-photon production of the
Higgs boson and of $W^{+}W^{-}$ pairs in $e^{+}e^{-}$, $PbPb$ and $pPb$ collisions at the Future Circular Collider (FCC). The processes are simulated with dedicated Monte Carlo codes, using the effective photon approximation for the $e^{+}e^{-}$, $PbPb$ and $pPb$ photon fluxes, at several center of mass energies. The analyses include electron-positron, lead-lead and proton-lead tagging, realistic acceptance and reconstruction efficiencies for the final-state particles, and selection criteria to remove the backgrounds. Observation of the proposed channels is achievable with the expected few ab−1 integrated luminosities at FCC.

Speaker: Patricia Rebello Teles (CBPF - Brazilian Center for Physics Research (BR))
• 58
Prospects of diffractive physics with the ATLAS forward detectors

The ATLAS Forward Proton (AFP) detector provides measurements of the momentum and emission angle of very forward protons. This enables the observation and measurement of a range of processes where one or both protons remain intact. Such processes are associated with elastic and diffractive scattering. In this talk, we give on overview of the technical details of the AFP, its current status as well as its associated physics program.

Speaker: Ivan Lopez Paz (Universitat Autònoma de Barcelona (ES))
• 59
The CMS-TOTEM Precision Proton Spectrometer

The CT-PPS (CMS-TOTEM Precision Proton Spectrometer) detector system consists of silicon tracking stations as well as timing detectors to measure both the position and direction of protons and their time-of-flight with precision of the order of 20 ps. They are located at around 200 m from the interaction point in the very forward region on both sides of the CMS experiment. CT-PPS is built to study Central Exclusive Production (CEP) in proton-proton collisions at LHC, including photon-photon production of W and Z boson pairs, high-mass diphoton and dilepton production, high-pT jet production, as well as searches for anomalous couplings and new resonances.

In 2016 the CT-PPS detector has taken data at high luminosity while fully integrated to the CMS data acquisition system. The total data collected correspond to around 15~${\rm fb}^{-1}$. In this presentation an overview of the CT-PPS project is given. The CT-PPS operation during 2016 and the new detector systems installed in 2017 are discussed. The expected performance and sensitivity to different physics processes are outlined.

Speaker: Mrs Maria Margherita Obertino (University and INFN, Torino)
• 60
Exclusive production of resonances in proton-proton collisions at high energies

A model for exclusive diffractive resonance production in proton-proton
collisions at high energies is presented. Cross sections are calculated by folding
the Pomeron-Pomeron total cross section (∗) with the Donnachie-Landshoff
parameterisation of the Pomeron flux in the proton(∗∗). The single differential
cross section dsigma/dM as well as the double differential cross section
dsigma/dMdp_T will be shown for the resonances f0(980) and f2(1270).
The range of x-values of the Pomeron flux accessible in these measurements

*) R.Fiore, L.Jenkovszky, R.Schicker, Resonance production in Pomeron-Pomeron
collisions at the LHC, Eur. Phys. J. C76 (2016) 1, 38

**) A.Donnachie, P.V.Landshoff, Hard diffraction: Production of high p_T jets,
W or Z, and Drell-Yan pairs, Nucl. Phys. B303 (1988), 634

Speaker: Rainer Schicker (Ruprecht-Karls-Universitaet Heidelberg (DE))
• Friday, June 30
• Cosmic Ray Session
• 61
Monte Carlo generators for cosmic ray interactions

I'll review the status and recent developments of Monte Carlo models of high energy hadronic interactions, employed in the cosmic ray field. A special attention will be devoted to the impact of the LHC data on the model improvements. Additionally, the potential of the forthcoming LHC measurements to discriminate between the underlying model approaches will be analysed. Finally, the relation to the ultra-high energy cosmic ray composition puzzle will be discussed.

Speaker: Sergey Ostapchenko (Frankfurt Institute for Advanced Studies (FIAS))
• 62
Hadronic interactions at ultra high energies

The Pierre Auger Observatory is an hybrid detector for cosmic ray showers with
energy above 1 EeV. This has allowed us to measure the proton-proton cross-section at sqrt(s)=55 TeV and to test other features of the hadronic interaction models, which are extrapolated from the LHC energy and different phase spaces.

The electromagnetic shower component, carrying most of its energy, is precisely measured using fluorescence telescopes, while the hadronic backbone of the shower is more directly tested by measuring the muons arriving to the surface detector. The analyses show that the models fail to describe these two components in a consistent way, predicting a smaller number of muons than what is observed.

We will discuss these results highlighting the points in which other measurements could help to set more direct constraints on the model features relevant for cosmic ray analyses.

Speaker: Sofia Andringa (LIP)
• 63
Proton-Air Cross Section and Composition of Ultra High Energy CR Observed By Telescope Array

Ultra high energy cosmic ray composition provides important clues as to the nature and location of exotic, unknown sources capable of accelerating particles to the highest energies in the observable universe. To understand the chemical composition of UHECRs, we require large statistical samples of data and accurate hadronic models able to predict important properties such as cross section, multiplicity, and inelasticity in the UHECR energy regime. Current generation cosmic ray observatories now have large enough apertures to collect sufficient statistical samples for energies $> 10^{18}$ eV, but hadronic modelling at these energies is still reliant upon phenomenological and the theoretical extrapolations based upon terrestrial accelerator data. UHECR data can be used to improve these extrapolations of the proton-air cross section, but large uncertainties remain for other hadronic model parameters. I will present the most recent measurement of the inelastic proton-air cross section at $\sqrt{s} = 95$ TeV measured by Telescope Array using high quality $X_{\mathrm{max}}$ data collected in hybrid observing mode. This measurement is also used to infer the total proton-proton cross section. In addition I will present results of a recent study of the uncertainty of $\left< X_{\rm max} \right>$ obtained from hadronic model generators widely used in UHECR simulation packages when we extrapolate results from energies available at the LHC to those of UHECR air showers. Finally, the most recent composition data observed by TA will be presented, using a larger exposure and greater sensitivity than has previously been published.

Speaker: William Hanlon (University of Utah)
• 64
Muon bundles from cosmic rays with ALICE

ALICE, a general purpose experiment designed to investigate nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC), has also been used to detect atmospheric muons produced by cosmic-ray interactions in the atmosphere. The large size and excellent tracking capability of the ALICE Time Projection Chamber are exploited to detect and reconstruct these muons. A program of cosmic-ray data taking was started in 2010 in periods when there is no beam circulating in the LHC. To date ALICE has acquired several million events with at least one muon. After a short summary of the previous LEP results, the analysis of the multiplicity distribution of the atmospheric muons detected by ALICE between 2010 and 2013 is presented, along with a comparison with Monte Carlo simulations. Special emphasis is given to the study of high multiplicity events, i.e. those containing more than 100 reconstructed muons. Such high multiplicity events demand primary cosmic rays with energy above 1016 eV, and it will be shown that the frequency of these events can besuccessfully described by assuming a heavy mass composition of primary cosmic rays in this energy range, using the most recent interaction models to describe the development of the air shower resulting from the primary interaction.

Speaker: Mario Sitta (Universita del Piemonte Orientale (IT))
• Coffee Break
• Heavy ions
• 65

We shall present theoretical predictions for production of
$J/\Psi$ meson, $\gamma\gamma$, one and two pairs of leptons
and $p \bar{p}$ in ultrarelativistic UPC.
Analyses are done in the impact parameter space equivalent photon approximation.
We use so-called realistic form factor which is a Fourier transform
of the charge distribution in nuclei.
We consider both ultraperipheral and for the first time semi-central collisions.

We get very good description of the latest ALICE data for single $J/\psi$
photoproduction for different centrality bins. We show that a correct interpretation
of data requires to use a modification of a photon flux.
Next, we will report on our results for light-by-light scattering.
Our rather optimistic predictions became a motivation for experimental groups
to perform corresponding experimental studies.
Our calculations were a source of a ATLAS Monte Carlo simulation.
A recent ATLAS measurement is a first experimental observation
of the PbPb$\to$PbPb$\gamma\gamma$ mechanism and $\gamma \gamma \to \gamma \gamma$ scattering.

Next we will discuss a electromagnetic double scattering
production of two positron-electron pairs.
Our calculations suggest that measurements (with the help of
detectors at the LHC) are possible in a near future. We get very good agreement with ALICE data
for single $e^+e^-$ pair production.

Finally we shall present very fresh results for $p \bar{p}$ production.
We are a first group which can describe, concurrently, angular distributions and total cross section
for $\gamma\gamma \to p \bar{p}$ process. We inserted this elementary cross section
into nuclear UPC calculations and, dependently on $z=\cos\theta$ limitation,
we get a cross section of the order of 1 mb.

Speaker: Mariola Klusek-Gawenda (IFJ PAS)
• 66
Photoproduction of vector mesons in ultraperipheral Pb-Pb collisions with ALICE at LHC

In Ultra-Peripheral Collisions (UPC), two nuclei pass close to each other
at an impact parameter greater than the sum of their radii; in such
collisions hadronic processes are strongly suppressed, while γ interactions
are enhanced with respect to minimum-bias collisions.
Photoproduction of vector mesons in UPC is a powerful tool to probe the
nuclear gluon distribution in the nucleus, for which there is considerable
uncertainty in the low-x region.
The ALICE collaboration has published measurements of UPC J/ψ and ψ(2S) photoproduction in LHC Run 1 at forward (J/ψ) and at mid-rapidity.
In addition the increased energy and more detailed measurements in the
forward region in Run 2 give access to significantly lower values of
Bjorken-x than in previous studies.
In this talk, the latest available results from Run 2 will be given, together
with results on photoproduction of ρ0 from Run 1 and 2 and a comparison
with theoretical models.

Speaker: Daniele De Gruttola (Universita e INFN, Salerno (IT))
• 67
Electromagnetic processes in ultra peripheral Pb+Pb collisions with ATLAS

The large equivalent-photon fluxes accompanying Pb ion beams at the LHC initiate photon- photon and photo-nuclear interactions which dominate when the colliding nuclei have large impact parameter (ultra-peripheral collisions). These electromagnetically-induced processes are sensitive to the nuclear wave-function and in particular the nuclear modifications of the nucleon parton distribution functions (nPDFs). As such, they are complementary to the ongoing p+A program at RHIC and the LHC, as well as the upcoming electron-ion collider (EIC) program in the US. High-mass dilepton pair continuum rates have been measured and compared with theoretical predictions to test expectations for two-photon interactions, and good agreement with model calculations is obtained. Also the evidence for the elastic scattering of photons γγ→γγ (“light-by-light” scattering) will be presented, a previously unobserved process made possible by the high photon flux and low event pileup provided by the LHC. While of intrinsic interest as a heretofore-unobserved standard model process, it has also been proposed as a clean channel for searches for beyond the standard model (BSM) physics.

Speaker: Marcin Guzik (AGH University of Science and Technology (PL))
• 68
Investigating saturation effects in Ultraperipheral Heavy Ion Collisions

The exclusive vector meson production cross section is one of the most promising observables to probe the high energy regime of the QCD dynamics. In particular, the squared momentum transfer (t) distributions are an important source of information about the spatial distribution of the gluons in the hadron and about fluctuations of the color fields. In this contribution we present our recent results for the Run II of the LHC considering the presence of the gluon saturation effects. In particular, we present a comprehensive analysis of the t - spectrum measured in exclusive ρ, ϕ and J/Ψ photoproduction in pp and PbPb collisions at the LHC. We demonstrate that gluon saturation suppresses the magnitude of the cross sections and shifts the position of the dips towards smaller values of t. Moreover, we demonstrate that our predictions describe the recent LHC data.

Speaker: Victor Gonçalves (Universidade Federal de Pelotas)
• Organization: Closing words
• Lunch