Low-x 2019

26 Aug 2019, 08:45 → 31 Aug 2019, 09:00 Europe/Rome

Nicosia, Cyprus

The purpose of the Low-x workshop is to stimulate discussions between experimentalists and theorists in diffractive hadronic physics, QCD dynamics at low-x, parton saturation and exciting problems in QCD at HERA, Tevatron, LHC, RHIC and the future EIC.

The conference venue will be at hotel The Landmark Nicosia Hotel (formerly Hilton Hotel) in Nicosia, Cyprus, from August 26th in the morning to August 31st at lunch time. Sessions will take place in room ``Akamas'', at the end of the hallway on the right-hand side from the entrance of the hotel. In order to benefit from special prices at the hotel for the conference the promo code will be indicated soon in this webpage. In addition to the registration for the workshop, please book directly your room at the hotel webpage.

The registration fee will be 300 Euros for participants of the workshop, and 100 Euros for companions. The registration fee can be paid with cash or together with the cost of Landmark Hotel. The fees cover all lunches, coffee breaks and the workshop dinner as well as a one-day tour on Wednesday in Cyprus and an afternoon tour in the Mountains on Thursday before the workshop dinner.

The Wednesday tour includes a visit to Chirokitia (the palaiolithic settlement), the roman theater of Kourion after Lemessos, Aphrodite’s birth place, the mosaics and the kings tombs, Latsi for lunch, afternoon in Paphos' old port, and on the way back a stop at Lefkara, return around 7:30 PM at Nicosia, Cyprus.

The Thursday tour includes a visit to the most famous monastery of Cyprus (Kykkos monastery), a stop on a village named Kakopetria (there is a church there in the UNESCO heritage) and also a stop on the village of Kalopanayiotis (there is another church there); people can walk around or go to a cafe.

Low-x is an annual workshop whose spirit is to favour fruitful and informal discussions between experimentalists and theorists in low-x, diffractive hadronic physics and exciting problems in QCD at HERA, Tevatron and LHC. Low-x has been held since DESY (1993), then Saclay (May 1994), Cambridge (July 1995), Durham (June 1996), Madrid (June 1997), Berlin (June 1998), Tel Aviv (June 1999), Oxford (July 2000), Cracow (June 2001), Antwerpen (September 2002), Nafplio (June 2003), Prague (September 2004), Sinaia (June 2005), Lisbon (June 2006), Helsinki (September 2007), Crete (July 2008), Ischia (September 2009), Kavala (June 2010), Santiago de Compostela (June 2011), Cyprus (June 2012), Eilat (June 2013), Kyoto (June 2014), Sandomierz (September 2015), Gyongyos (June 2016), Bisceglie (June 2017) and Reggio Calabria (August 2018).

A note about the power plugs: Cyprus uses the same type of plugs as in the UK.  Driving is also the same as in the UK.

 

 

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The Workshop is organized and sponsored by the University of Kansas, the University of Cyprus, ExtreMe Matter Institute at GSI (EMMI) and CERN

 

Monday, 26 August

08:45 → 09:00 Welcome

Speakers: Christophe Royon (The University of Kansas (US)), Fotios Ptochos (University of Cyprus (CY))

09:00 → 09:30 Latest results on double parton scattering and MC tuning from CMS

Speaker: Radek Zlebcik (Deutsches Elektronen-Synchrotron (DE))

cms_Tunes_DPS.pdf

09:30 → 10:00 Measurements of multi-parton interactions at ATLAS

Speaker: Tibor Zenis (Comenius University (SK))

Zenis_MPI_ATLAS.pdf

10:00 → 10:25 J/\psi production in hadron scattering: two parton showers contribution

Speaker: Eugene Levin (Tel Aviv University)

Levin2Lowx2019.pdf

10:25 → 10:50 Coffee break

10:50 → 11:15 Regge cuts in the Reggeized gluon channel

Speaker: Victor Fadin (Budker Institute of Nuclear Physics)

Regge cuts in the Reggeized gluon channel.pdf

11:15 → 11:40 BFKL resummation in inclusive processes

Speaker: Alessandro Papa (Universita` della Calabria & INFN-Cosenza)

low-x_2019.pdf

11:40 → 12:05 Low $x$ physics and saturation in terms of TMD distributions

One of the main difficulties to understand the continuity between low x physics and more standard QCD factorization frameworks which apply for more moderate energies is the very nature of the parton distributions involved. I will argue that low x physics can be understood as the eikonal limit of an infinite twist TMD distribution framework, and discuss the consequences of this observation for saturation and for gluon polarizations at small x.

Speaker: Renaud Boussarie (Brookhaven National Lab)

BoussarieLowX2019.pdf

12:05 → 12:40 Discussion session: DPS, saturation

Speakers: Brian Foster (University of Oxford (GB)), Dimitri Colferai, Eugene Levin (Tel Aviv University)

12:40 → 14:00 Lunch break

14:00 → 14:30 Forward photon measurements with ALICE at the LHC as a probe for low-x gluons

Speaker: Thomas Peitzmann (Nikhef National institute for subatomic physics (NL))

lowx-2019-focal.pdf

14:30 → 15:00 Measurements of event properties and correlations in multi jet events in CMS

Measurements of event properties and correlations in multi jet events in CMS are reviewed.

Speaker: Cristian Baldenegro Barrera (The University of Kansas (US))

event_shape_variables.pdf

15:00 → 15:25 Mueller Tang cross sectiona at NLL

Speaker: Federico Deganutti

low-x_cyprus.pdf

15:25 → 15:50 Topological charge fluctuations in the Glasma

Speaker: Pablo Guerrero Rodríguez (UGR)

topological_charge_fluctuations.pdf

15:50 → 16:15 Coffee break

16:15 → 16:40 The NL BFKL vertex for Mueller-Tang jets in the soft-gluon approximation

Speaker: Dimitri Colferai

colferai.pdf

16:40 → 17:05 Forward jet cross sections: from trijet to NLO dijet

Using the formalism of the light-cone wave function in pQCD together with the hybrid factorization, we compute the cross-section for two and three particle production at forward rapidities in proton-nucleus collisions. We focus on the quark channel, in which the three produced partons -- a quark accompanied by a gluon pair, or two quarks plus one antiquark -- are all generated via two successive splittings starting with a quark that was originally collinear with the proton. The produced partons are put on-shell by their scattering off the nuclear target, described as a Lorentz-contracted "shockwave". By using the three-parton component of the quark light-cone wave function, together with the virtual corrections, we can then present our progress on the computation of the next-to-leading order correction to the cross-section for the production of a pair of jets.

Speaker: Yair Mulian

Low-x2019Mulian.pdf

17:05 → 17:30 Impact parameter dependence of colinearly improved Balitsky-Kovchegov evolution

Speaker: Marek Matas (CERN)

Impact%20parameter%20dependence%20of%20colinearly%20improved%20Balitsky-Kovchegov%20evolution-2.pdf

17:30 → 17:55 BFKL Resummation in the inclusive Higgs Boson Plus Jet production at the LHC

The inclusive production of a Higgs boson and of a jet at the LHC, featuring a wide separation in rapidity, is an interesting probe process for the investigation of the BFKL mechanism of resummation of energy logarithms in the QCD perturbative series. Here, we present for the first time a partial next-to-leading order BFKL analysis for cross sections and azimuthal correlations.

Speaker: Mohammed Maher Abdelrahim Mohammed (Università della Calabria and INFN - Gruppo collegato di Cosenza)

TalkM-2.pdf

17:55 → 18:30 Discussion session: jet gap jets, BFKL saturation

Speakers: Dimitri Colferai, Eugene Levin (Tel Aviv University)

18:30 → 20:30 Reception

Tuesday, 27 August

09:00 → 09:30 Recent PDF results from top physics and heavy flavour results at CMS

Speaker: Katarzyna Wichmann (Deutsches Elektronen-Synchrotron (DE))

kwichmann-lowx19-cms.pdf

09:30 → 09:55 Multiple scattering effects in heavy quarkonia hadroproduction

Speaker: Leszek Motyka

jpsilowx19.pdf

09:55 → 10:20 Correlations at unequal rapidity in the dilute limit of JIMWLK

Unequal rapidity correlations can be studied within the stochastic Langevin picture of JIMWLK evolution in the Colour Glass Condensate effective field theory. By evolving the classical field in the direct and complex conjugate amplitudes, the Langevin formalism can be used to study two-particle production at large rapidity separations. The evolution between the rapidities of the two produced particles can be expressed as a linear equation, even in the full nonlinear limit. In addition, the Langevin formalism for two-particle correlations reduces to a BFKL picture in the dilute limit and in momentum space, providing an interpretation of BFKL evolution as a stochastic process for colour charges.

Speaker: Andrecia Ramnath (University of Jyvaskyla)

Ramnath Low-x.pdf

10:20 → 10:45 Introduction to XFitter

Speaker: Katarzyna Wichmann (Deutsches Elektronen-Synchrotron (DE))

kwichmann-lowx19-xfitter.pdf

10:45 → 11:10 Coffee break

11:10 → 11:35 xFitter project - a framework for QCD studies

Speaker: Agnieszka Luszczak

aluszczak-lowx2019.pdf

11:35 → 12:05 Determination of proton parton distribution functions using ATLAS data

Speaker: Lorenzo Bellagamba (Universita e INFN, Bologna (IT))

Low-x_bellagamba.pdf

12:05 → 12:40 Discussion session: PDFs, DGLAP...

Speakers: Brian Foster (University of Oxford (GB)), Katarzyna Wichmann (Deutsches Elektronen-Synchrotron (DE)), Leszek Motyka

12:40 → 14:00 Lunch break

14:00 → 14:25 Prospects for measurements of H/Z production cross section ratios using CMS Run II data

Speaker: Louis Moureaux (Universite Libre de Bruxelles (BE))

Moureaux_Lowx2019-handout.pdf

14:25 → 14:50 Initial-state fluctuations and anisotropies in heavy-ion collisions

Speakers: Cyrille Marquet (CPHT - Ecole Polytechnique), Cyrille Marquet (Theory Division - CERN), Cyrille Michel Marquet (Universidade de Santiago de Compostela (ES))

marquet.pdf

14:50 → 15:15 Sudakov resummation in the CGC framework

In this talk we would like to present our recent works on how to incorporate Sudakov resummation into the dilute-dense factorization framework.

Speaker: Dr Shu-yi Wei (CPHT, Ecole Polytechnique)

Cyprus.pdf

15:15 → 15:40 Thermal radiation and inclusive production in the CGC/saturation approach at high energies for hadron-hadron and ion-ion collision

Speaker: Eugene Levin (Tel Aviv University)

LevinLowx2019.pdf

15:40 → 16:10 Coffee break

16:10 → 16:35 Vertices of three reggeized gluons and the unitarity corrections to the propagator of reggeized gluons

High energy QCD hadronic interactions in the Regge kinematics, when the transferred transverse momenta are much smaller than an energies of colliding particles, can be described by the interaction of gluons with reggeized ones ("reggeized gluons", reggeons). The description of these processes was firstly introduced in series of L.N. Lipatov's papers. Calculations of the amplitudes of different scattering processes in this approach reveal also a so-called multi-Regge structure of the amplitudes. Therefore, in order to analyze different scattering processes with multi-Regge kinematics, L.Lipatov proposed an effective action based on QCD properties at high energy.

We develop the effective action formalism, see \cite{1,2,3,4,5,6} , based on the reggeized gluons as the main degrees of freedom, which can be considered as a reformulation of the RFT (Regge field theory) calculus for the case of high-energy QCD. The perturbation theory is based on the knowledge of the classical solutions of equations of motion and loops contributions to effective action.

Our main goal in this study is to obtain unitarity corrections to amplitudes. The unitarity corrections to the propagator of reggeized gluons calculated in the framework of QCD RFT require a knowledge of the expressions for reggeon propagator and vertices of the interaction of three reggeons to one QCD loop precision. In the last paper \cite{6}, we calculated the vertex of interactions of $A_+A_+A_-$ Reggeon fields to this precision. We demonstrated, that all loop leading logarithmic order contributions to the vertex can be summed through the integro-differential equation similar to the BFKL one.

\renewcommand\bibsection{\nsection{References}}

\begin{thebibliography}{4}

\bibitem{1}
S.Bondarenko, L.Lipatov, S.Pozdnyakov, A.Prygarin. One loop light-cone QCD, effective action for reggeized gluons and QCD RFT calculus (2017) //
Eur. Phys. J. 2017. Vol. {\bf C77}:630.

\bibitem{2}
S.Bondarenko, S.S.Pozdnyakov (2018). NNLO classical solution for Lipatov's effective action for reggeized gluons // Submitted to Int.J.Mod.Phys. A, arXiv:1802.05508

%\cite{Bondarenko:2018kqs}
\bibitem{3}
S.Bondarenko, S.S.Pozdnyakov (2018). S-matrix and productions amplitudes in high energy QCD //
Phys.Lett. B783 207-211
%%CITATION = ARXIV:1803.04131;%%

\bibitem{4}
S. Bondarenko, S.S. Pozdnyakov (2018). On correlators of Reggeon fields and operators of Wilson lines in high energy QCD, Int.J.Mod.Phys. A33 (2018) no.35, 1850204\

\bibitem{5}
S. Bondarenko and S. Pozdnyakov (2018). On QCD RFT corrections to the propagator of reggeized gluons, arXiv:1903.11288 [hep-th]\

\bibitem{6}
S. Bondarenko and S. Pozdnyakov. On reggeization of vertex of three reggeized gluons in high energy QCD,
arXiv:1905.04916 [hep-ph].
%%CITATION = ARXIV:1905.04916;%%

\end{thebibliography}

Speaker: Semyon Pozdnyakov (Saint Petersburg State University, Ariel University)

small_x_conf__Copy___Copy___Copy_%20%281%29.pdf

16:35 → 17:05 UPC results from ALICE

Speaker: Roman Lavicka (Czech Technical University (CZ))

lowx19.pdf

17:05 → 18:05 Discussion session: Heavy ions

Speaker: Cyrille Marquet (CPHT - Ecole Polytechnique)

Wednesday, 28 August

08:30 → 19:30 Workshop tour

Thursday, 29 August

09:00 → 09:30 V+jets production and Jet cross sections at CMS and tests of QCD

Speaker: Bugra Bilin (Universite Libre de Bruxelles (BE))

bbilin_low-x2019_final

09:30 → 10:00 NNLO QCD fits to jets and extraction of alpha_s

Speaker: Katarzyna Wichmann (Deutsches Elektronen-Synchrotron (DE))

kwichmann-lowx19-hera.pdf

10:00 → 10:30 Measurements of single diffraction using forward proton tagging at ATLAS

Speaker: Rafał Staszewski (IFJ PAN Cracow (PL))

Lowx2019_staszewski.pdf

10:30 → 11:00 Coffee break

11:00 → 11:30 Diffractive PDF determination from HERA inclusive and jet data at NNLO QCD

Speaker: Radek Zlebcik (Deutsches Elektronen-Synchrotron (DE))

dPDFs.pdf

11:30 → 12:00 Recent results on soft and forward physics from CMS

Recent results on soft and forward physics from CMS are reviewed.

Speaker: Cristian Baldenegro Barrera (The University of Kansas (US))

cms_soft.pdf

12:00 → 12:30 LHCf forward physics results

The main aim of the LHC forward (LHCf) experiment is to provide precise measurements of the particles production spectra in the forward region of the hadronic collisions. These high energy calibration data are very important for the tuning of hadronic interaction models used by ground-based cosmic rays experiments. LHC is the best place where we can perform these measurements, because proton-proton collisions at √s = 14 TeV is equivalent to the interaction of a 10^17 eV cosmic ray with the atmosphere.
LHCf makes use of two small sampling calorimeters installed at ±140 m from LHC IP1, so that it can detect neutral particles produced by p-p and p-ion collisions with pseudo-rapidity η > 8.4.
In the past years, LHCf acquired data in p-p and p-ion collisions at different energies (p-p at √s = 0.9, 2.76, 7 and 13 TeV; p-Pb at √sNN = 5.02 and 8.1 TeV). In this talk, we will present the analysis results published by the collaboration, relative to neutrons, photons and π0 production spectra, compared with models predictions.
We will also present some preliminary results relative to the ATLAS-LHCf common analysis, from which we expect to significantly increase the impact of LHCf measurements, discriminating between diffractive and non- diffractive events by the use of ATLAS information in the central region.
A short overview of the future activities foreseen at the LHC-Run3 (14 TeV p-p and p-O runs) will also be given.

Speaker: Oscar Adriani (Dipartimento di Fisica)

Adriani_LHCf_LowX_2019.pdf

12:30 → 13:00 Discussion session: inclusive diffraction

Speakers: Michael Albrow (Fermi National Accelerator Lab. (US)), Rafał Staszewski (IFJ PAN Cracow (PL))

13:00 → 14:30 Lunch break

14:30 → 23:30 Mountain tour and workshop dinner

Friday, 30 August

09:00 → 09:30 Recent results from PPS and PPS status and prospects

Speaker: Andrea Bellora (Universita e INFN Torino (IT))

Bellora_Low-x_2019.pdf

09:30 → 10:00 Recent results CMS and TOTEM on exclusive production, light by light scattering and diffraction

Recent results CMS and TOTEM on exclusive production, light by light scattering and diffraction are reviewed.

Speaker: Michael Albrow (Fermi National Accelerator Lab. (US))

Albrow-Cyprus-CMSTotemFinal.pdf

Albrow-Cyprus-CMSTotemFinal.pptx

10:00 → 10:25 Anomalous coupling studies and the pomeron structure at the LHC

Speaker: Christophe Royon (The University of Kansas (US))

lowx2019.pdf

10:25 → 10:50 Coffee break

10:50 → 11:15 Axion-like particles in light-by-light scattering in pp, pPb, and Ar-Ar collisions

Speaker: Cristian Baldenegro Barrera (The University of Kansas (US))

alp_cristian.pdf

11:15 → 11:40 Searches for Dark Matter at the LHC in forward proton mode

Speaker: Valery Khoze (University of Durham (GB))

11:40 → 12:10 Studies of Central Exclusive Production and Soft QCD phenomena at LHCb

The LHCb detector at the LHC offers unique coverage of forward rapidities. This enables complementary measurements of soft QCD phenomena to those at the other LHC detectors. Measurements of the inelastic cross-section and of particle production will be presented. Measurements of Central Exclusive Production (CEP) at LHCb will also be presented. These measurements probe QCD, allowing investigation of the nature of pomerons, and provide constraints on low-x gluon phenomenology, probing potential saturation effects. CEP measurements at LHCb in the most recent LHC run have significantly benefited from the installation of new high rapidity shower counters (the “HeRSCHel” subdetector). The performance and use of this new detector for CEP studies will also be discussed.

Speaker: Lavinia-Elena Giubega (IFIN-HH (RO))

ElenaGiubega_Central Exclusive Production and Soft QCD at LHCb_Cyprus.pdf

12:10 → 12:45 Discussion session: exclusive diffraction

Speakers: Christophe Royon (The University of Kansas (US)), Valery Khoze (University of Durham (GB))

ForTsorgo2019%20%28dragged%29.pdf

12:45 → 14:00 Lunch break

14:00 → 14:30 Review of TOTEM results

Speaker: Jan Kaspar (Acad. of Sciences of the Czech Rep. (CZ))

jan_kaspar_TOTEM.pdf

14:30 → 14:55 Scaling properties of elastic pp and ppbar scattering at LHC energies

Speaker: Tamas Csorgo (Hungarian Academy of Sciences (HU))

2019-08-30-Csorgo-Pasechnik-Ster-Szanyi-Scaling-Low-x-19-Cyprus.pptx

2019-08-30-Csorgo-Pasechnik-Ster-Szanyi-Scaling-Low-x-19-Cyprus-v2.pdf

14:55 → 15:20 Photon-induced processes in production of heavy particle pairs at the LHC

Speaker: Marta Luszczak (University of Rzeszow)

luszczak-Lowx-2019.pdf

15:20 → 15:50 Coffee break

15:50 → 16:20 Results on Total and Elastic Cross Sections in p+p collisions at sqrt(s) = 200 GeV with the STAR Detector at RHIC

Speaker: Dr Wlodek Guryn (Brookhaven National Laboratory)

GurynLow-x2019.pdf

16:20 → 16:45 Roman pots and the impact parameter for ion-ion

Speaker: Janusz Chwastowski (Polish Academy of Sciences (PL))

JChwastowski_Lowx2019.pdf

16:45 → 17:10 Recent results on central exclusive production within the tensor-pomeron and vector-odderon approach

Speaker: Piotr Lebiedowicz (Institute of Nuclear Physics PAN)

Lowx2019_Lebiedowicz.pdf

17:10 → 18:00 Discussion session: Soft and hard diffraction

Speakers: Tamas Csorgo (Hungarian Academy of Sciences (HU)), Valentina Avati (AGH University of Science and Technology (PL))

Albrow%20Lowx%20ISR%20data%20.pdf

Albrow%20Lowx%20ISR%20data%20.pptx

Albrow-Lowx-SAS.pdf

Albrow-Lowx-SAS.pptx

levin_plb.pdf

18:00 → 18:10 Closing items

Speakers: Christophe Royon (The University of Kansas (US)), Fotios Ptochos (University of Cyprus (CY))