The present work is devoted to developing the integrated hydrokinetic model (iHKM) for relativistic nucleus-nucleus collisions. While the previous cycle of works on this topic focused on ultrarelativistic collisions at the top RHIC and different LHC energies, the current work addresses relativistic collisions at the lower energies, specifically ranging from approximately 2 to 50 GeV per nucleon pair in the center-of-mass colliding system. In such collisions, the formation times for the initial state of dense matter can be up to three orders of magnitude longer than those in ultrarelativistic collisions. This difference reflects a fundamentally distinct nature and formation process, particularly regarding the possible stages of initial state evolution, including thermalization (which may be only partial at very low collision energies), subsequent hydrodynamic expansion, and the final transition of matter evolution into a hadronic cascade. These stages, which are fully realized in ultrarelativistic reactions, can also occur within the energy range of BES RHIC, albeit with distinct timescales. This publication not only advances the theoretical development of iHKM [referred to, if necessary, as the extended version of integrated hydrokinetic model (<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>iHKM</mi><mi>e</mi></math>)], but also provides examples of model applications for calculating observables. A systematic description across a wide range of experimental energies, which is preliminary yet quite satisfactory, for spectra, flow, and femtoscopy, will follow this study.

Ukraine

Musfer Adzhymambetov

Poland

Yuri Sinyukov

Extension of the integrated hydrokinetic model to nuclear collision energies relevant for the RHIC Beam-Energy Scan program and the research program at GSI-FAIR

The cross sections for the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi><mo>→</mo><mi>p</mi><mi>p</mi><mi>η</mi></mrow></math> reaction are evaluated at energies relevant for the HADES, PANDA, and SIS100 experiments at GSI-FAIR (Facility for Antiproton and Ion Research). Consideration includes the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>η</mi></math>-bremsstrahlung mechanism involving intermediate proton exchange via the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>π</mi><mn>0</mn></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>η</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ω</mi></math> exchanges and the mechanism involving the nucleon resonances <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1650</mn><mo>)</mo></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1710</mn><mo>)</mo></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1880</mn><mo>)</mo></mrow></math> excited via the pseudoscalar- and/or vector-meson exchanges, depending on the model. The role of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ω</mi><mi>ω</mi></mrow></math>- and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>ρ</mi><mn>0</mn></msup><msup><mi>ρ</mi><mn>0</mn></msup></mrow></math>-fusion processes with the Reggeized vector-meson exchanges is also discussed. The calculation is done in an effective Lagrangian approach. To determine the parameters of the model, the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>γ</mi><mi>p</mi><mo>→</mo><mi>η</mi><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>η</mi><mi>n</mi></mrow></math> reactions are studied and the results are then compared with the Crystal Ball and CLAS data. For the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi><mo>→</mo><mi>p</mi><mi>p</mi><mi>η</mi></mrow></math> reaction, the model results are compared with the energy dependence of the cross section measured far from the threshold and with the differential distributions <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>d</mi><mi>σ</mi><mo>/</mo><mi>d</mi><mo form="prefix">cos</mo><msub><mi>θ</mi><mi>η</mi></msub></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>d</mi><mi>σ</mi><mo>/</mo><mi>d</mi><msub><mi>p</mi><mi>η</mi></msub></mrow></math> measured by the DISTO Collaboration. The comparison shows that the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></mrow></math> resonance is the dominant contribution and that other contributions are also important due to interference effects. Assuming that the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ρ</mi></math> exchange is the dominant resonant excitation process, the model is able to describe the available data, e.g., it reproduces the shape of the angular distributions measured by the DISTO Collaboration. Predictions are given for the HADES experiment at center-of-mass energy of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>3.46</mn></mrow></math> GeV, which can be verified in the near future, and for planned PANDA and SIS100 experiments at higher energies.

Piotr Lebiedowicz

Exclusive <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>η</mi></math> production in proton-proton collisions at energies available at the GSI Facility for Antiproton and Ion Research

The identification of jets originating from quarks and gluons, often referred to as quark/gluon tagging, plays an important role in various analyses performed at the Large Hadron Collider, as Standard Model measurements and searches for new particles decaying to quarks often rely on suppressing a large gluon-induced background. This paper describes the measurement of the efficiencies of quark/gluon taggers developed within the ATLAS Collaboration, using $\sqrt{s} = 13$ TeV proton–proton collision data with an integrated luminosity of 140 fb $^{-1}$ collected by the ATLAS experiment. Two taggers with high performances in rejecting jets from gluon over jets from quarks are studied: one tagger is based on requirements on the number of inner-detector tracks associated with the jet, and the other combines several jet substructure observables using a boosted decision tree. A method is established to determine the quark/gluon fraction in data, by using quark/gluon-enriched subsamples defined by the jet pseudorapidity. Differences in tagging efficiency between data and simulation are provided for jets with transverse momentum between 500 GeV and 2 TeV and for multiple tagger working points.

France

G. Aad

B. Abbott

Germany

K. Abeling

N.J. Abicht

S.H. Abidi

Morocco

A. Aboulhorma

Israel

H. Abramowicz

H. Abreu

Y. Abulaiti

Italy

United Kingdom

B.S. Acharya

C. Adam Bourdarios

L. Adamczyk

S.V. Addepalli

M.J. Addison

J. Adelman

A. Adiguzel

T. Adye

A.A. Affolder

Switzerland

Y. Afik

Spain

M.N. Agaras

J. Agarwala

A. Aggarwal

Romania

C. Agheorghiesei

A. Ahmad

Azerbaijan

F. Ahmadov

Canada

W.S. Ahmed

S. Ahuja

X. Ai

G. Aielli

A. Aikot

M. Ait Tamlihat

B. Aitbenchikh

I. Aizenberg

M. Akbiyik

Sweden

T.P.A. Åkesson

A.V. Akimov

Japan

D. Akiyama

N.N. Akolkar

K. Al Khoury

G.L. Alberghi

J. Albert

P. Albicocco

G.L. Albouy

S. Alderweireldt

M. Aleksa

I.N. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

F. Alfonsi

M. Algren

M. Alhroob

Czechia

B. Ali

H.M.J. Ali

S. Ali

S.W. Alibocus

M. Aliev

G. Alimonti

W. Alkakhi

C. Allaire

B.M.M. Allbrooke

J.F. Allen

Chile

C.A. Allendes Flores

P.P. Allport

A. Aloisio

Argentina

F. Alonso

C. Alpigiani

M. Alvarez Estevez

A. Alvarez Fernandez

M. Alves Cardoso

M.G. Alviggi

M. Aly

Brazil

Y. Amaral Coutinho

A. Ambler

C. Amelung

M. Amerl

C.G. Ames

D. Amidei

Portugal

S.P. Amor Dos Santos

K.R. Amos

Norway

V. Ananiev

C. Anastopoulos

T. Andeen

J.K. Anders

S.Y. Andrean

A. Andreazza

S. Angelidakis

A. Angerami

A.V. Anisenkov

A. Annovi

C. Antel

M.T. Anthony

E. Antipov

M. Antonelli

F. Anulli

M. Aoki

T. Aoki

J.A. Aparisi Pozo

M.A. Aparo

L. Aperio Bella

C. Appelt

Performance and calibration of quark/gluon-jet taggers using 140 fb$^{−1}$ of $\textit{pp}$ collisions at ${{\sqrt{\boldsymbol s}\bf = 13}}$ TeV with the ATLAS detector * We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; Minciencias, Colombia; MEYS CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRI, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MEiN, Poland; FCT, Portugal; MNE/IFA, Romania; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DSI/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taipei; TENMAK, Türkiye; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, CANARIE, CRC and DRAC, Canada; PRIMUS 21/SCI/017 and UNCE SCI/013, Czech Republic; COST, ERC, ERDF, Horizon 2020, ICSC-Next Generation EU and Marie Skłodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and MINERVA, Israel; Norwegian Financial Mechanism 2014-2021, Norway; NCN and NAWA, Poland; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom.

We evaluate the cross section for the <math><mi>p</mi><mi>p</mi><mo>→</mo><mi>p</mi><mi>p</mi><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo></math> and <math><mi>p</mi><mover><mi>p</mi><mo>¯</mo></mover><mo>→</mo><mi>p</mi><mover><mi>p</mi><mo>¯</mo></mover><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo></math> reactions at near threshold energies relevant for the HADES and PANDA experiments at GSI-FAIR. We assume that at energies close to the threshold the <math><mi>ω</mi><mi>ω</mi><mo>→</mo><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo></math> and <math><msup><mi>ρ</mi><mn>0</mn></msup><msup><mi>ρ</mi><mn>0</mn></msup><mo>→</mo><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo></math> fusion processes are the dominant production mechanisms. The vertex for the <math><mi>V</mi><mi>V</mi><mo>→</mo><msub><mi>f</mi><mn>1</mn></msub></math> coupling is derived from an effective coupling Lagrangian. The <math><msub><mi>g</mi><mrow><mi>ρ</mi><mi>ρ</mi><msub><mi>f</mi><mn>1</mn></msub></mrow></msub></math> coupling constant is extracted from the decay rate of <math><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo><mo>→</mo><msup><mi>ρ</mi><mn>0</mn></msup><mi>γ</mi></math> using the vector-meson-dominance ansatz. We assume <math><msub><mi>g</mi><mrow><mi>ω</mi><mi>ω</mi><msub><mi>f</mi><mn>1</mn></msub></mrow></msub><mo>=</mo><msub><mi>g</mi><mrow><mi>ρ</mi><mi>ρ</mi><msub><mi>f</mi><mn>1</mn></msub></mrow></msub></math>, equality of these two coupling constants, based on arguments from the naive quark model and vector-meson dominance. The amplitude for the <math><mi>V</mi><mi>V</mi><mo>→</mo><msub><mi>f</mi><mn>1</mn></msub></math> fusion, supplemented by phenomenological vertex form factors for the process, is given. The differential cross sections at energies close to the threshold are calculated. In order to determine the parameters of the model the <math><mi>γ</mi><mi>p</mi><mo>→</mo><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo><mi>p</mi></math> reaction is discussed in addition and results are compared with the CLAS data. The possibility of a measurement by HADES@GSI is presented and discussed. We perform a Monte Carlo feasibility simulation of the <math><mi>p</mi><mi>p</mi><mo>→</mo><mi>p</mi><mi>p</mi><msub><mi>f</mi><mn>1</mn></msub></math> reaction for <math><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>3.46</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> with the <math><msub><mi>f</mi><mn>1</mn></msub></math> decaying into the <math><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> (not shown explicitly) and <math><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>η</mi><mo>(</mo><mo>→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mo>)</mo></mrow></math> final states using the PLUTO event generator. The latter <math><msub><mi>f</mi><mn>1</mn></msub></math> decay is especially promising as a peak in the <math><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mi>η</mi></math> mass distribution should be observable by HADES.

Otto Nachtmann

Piotr Salabura

Antoni Szczurek

Exclusive <math><msub><mi>f</mi><mn>1</mn></msub><mo>(</mo><mn>1285</mn><mo>)</mo></math> meson production for energy ranges available at the GSI-FAIR with HADES and PANDA

The production of 
					 baryons in proton-proton collisions at a centre-of-mass energy of 
					 is measured in the transverse-momentum range 
					 and the rapidity range 
					. The data used in this measurement correspond to an integrated luminosity of 
					, recorded by the LHCb experiment during 2016. The ratio of the 
					 production cross-section times the branching fraction of the 
					 decay relative to the prompt 
					 production cross-section is found to be 
					, assuming the central value of the measured 
					 lifetime, where the first uncertainty is statistical and the second systematic.
				

R. Aaij

C. Abellán Beteta

T. Ackernley

B. Adeva

M. Adinolfi

H. Afsharnia

C.A. Aidala

S. Aiola

Z. Ajaltouni

S. Akar

J. Albrecht

F. Alessio

M. Alexander

A. Alfonso Albero

G. Alkhazov

P. Alvarez Cartelle

A.A. Alves Jr

S. Amato

Y. Amhis

L. An

L. Anderlini

G. Andreassi

M. Andreotti

F. Archilli

A. Artamonov

M. Artuso

K. Arzymatov

E. Aslanides

M. Atzeni

B. Audurier

S. Bachmann

J.J. Back

S. Baker

V. Balagura

W. Baldini

A. Baranov

R.J. Barlow

S. Barsuk

W. Barter

M. Bartolini

F. Baryshnikov

J.M. Basels

G. Bassi

V. Batozskaya

B. Batsukh

A. Battig

A. Bay

M. Becker

F. Bedeschi

I. Bediaga

A. Beiter

L.J. Bel

V. Belavin

S. Belin

V. Bellee

K. Belous

I. Belyaev

G. Bencivenni

E. Ben-Haim

S. Benson

S. Beranek

A. Berezhnoy

R. Bernet

D. Berninghoff

Measurement of 
					 production in pp collisions at 
					 TeV Supported by CERN and national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (USA). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from AvH Foundation (Germany); EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union); ANR, Labex P2IO and OCEVU, and Région Auvergne-Rhône-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, and the Thousand Talents Program (China); RFBR, RSF and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Royal Society and the Leverhulme Trust (United Kingdom).