Suchergebnisse

We study the in-medium effects in strangeness production in heavy-ion collisions at (sub)threshold energies of (1-2)A GeV based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach. The in-medium modifications of the antikaon (K̄=K-,K̄0) properties are described via the self-consistent coupled-channel unitarized scheme based on a SU(3) chiral Lagrangian which incorporates explicitly the s and p waves of the kaon-nucleon interaction. This scheme provides the antikaon potential, spectral functions, and reaction cross sections as well as their dependence on baryon density, temperature, and antikaon momentum in the nuclear medium, which are incorporated in the off-shell dynamics of the PHSD. The in-medium modification of kaons (K=K+,K0) are accounted via the kaon-nuclear potential, which is assumed to be proportional to the local baryon density. The manifestation of the medium effects in observables is investigated for the K and K̄ rapidity distributions, pT spectra, the polar and azimuthal angular distributions, and directed (v1) and elliptic (v2) flows in C+C, Ni+Ni, and Au+Au collisions. We find - by comparison to experimental data from the KaoS, FOPI, and HADES Collaborations - that the modifications of (anti)kaon properties in nuclear matter are necessary to explain the data in a consistent manner. Moreover, we demonstrate the sensitivity of kaon observables to the equation of state of nuclear matter. ; Furthermore, we acknowledge support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Grant No. BR 4000/7-1, by the Russian Science Foundation Grant 19-42-04101, and by the GSI-IN2P3 agreement under Contract No. 13-70. L.T. acknowledges support from the Deutsche Forschungsgemeinschaft (DFG, German research Foundation) under the Projects No. 383452331 (Heisenberg Programme) and No. 411563442 (Hot Heavy Mesons). Her research has been also supported by the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2016-81114-P and Ministerio de Ciencia e Innovación under Contract No. PID2019-110165GB-I00. This project has, furthermore, received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 824093 (STRONG-2020). Also we acknowledge support via the COST Action THOR, CA15213, and CRC-TR 211 "Strong-interaction matter under extreme conditions," Project No. 315477589-TRR 211. The computational resources were provided by the LOEWE Center for Scientific Computing and the "Green Cube" at GSI, Darmstadt.

The possibility of separating quark and gluon jets in heavy ion collisions, both in the presence of the jet
quenching effect and in its absence, has been investigated. Using machine learning methods, a technique
has been developed to recover the fraction of quark and gluon jets, using variables characterizing the shape,
multiplicity, and charge of the jet. The potential of using these variables to study the characteristics of the
dense medium that arises during high-energy ion collisions has been demonstrated.

The introduction of a two-body spin-orbit force in the effective nuclear interaction is studied as a possible solution to difficulties encountered in the generator-coordinate description of heavy-ion collisions. The general framework of the method is presented in a case where the colliding nuclei are described in the jj-coupling scheme. The angular momentum projection is discussed and the promotion is shown to provide a valuable test of the correctness of the matrix elements. Properties of the spin-orbit force are studied and illustrated on several examples with a particular emphasis on the α + 12C system.

Heavy-ion-induced projectile fragmentation reactions at Fermi energies are of interest to investigate the properties
of nuclei far from the valley of stability, nuclear potentials, to get knew knowledge about nuclear equation of state.
Isotopes far from stability line can be useful for various applications. It is therefore of interest to predict relative
yields of isotopes and their energies with high precision. Here we treat such reactions in a microscopic approach,
which consists of several steps: initialization of ground states of the colliding nuclei, dynamical evolution until
the freeze-out point where the primary fragments can be identified, calculation of the excitation energy of
the primary fragments, and their de-excitation. For the dynamical evolution we use a Boltzmann–Vlasov type
transport equation, and for the de-excitation a statistical multi-fragmentation description. We apply this approach
to collisions of projectile nuclei 40Ar on target 9Be at energy 36.5 A MeV, obtain isotope distributions and velocity
spectra of the produced isotopes and compare the results of our calculations to experimental data obtained at
COMBAS set-up in JINR.

This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark–Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton–proton, proton–nucleus and nucleus–nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photoproduction in nucleus–nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7 $\mathrm{th}$ Framework Programme.

Microscopic methods and tools to describe nuclear dynamics have considerably been improved in the past few years. They are based on the time-dependent Hartree-Fock (TDHF) theory and its extensions to include pairing correlations and quantum fluctuations. The TDHF theory is the lowest level of approximation of a range of methods to solve the quantum many-body problem, showing its universality to describe many-fermion dynamics at the mean-field level. The range of applications of TDHF to describe realistic systems allowing for detailed comparisons with experiment has considerably increased. For instance, TDHF is now commonly used to investigate fusion, multi-nucleon transfer and quasi-fission reactions. Thanks to the inclusion of pairing correlations, it has also recently led to breakthroughs in our description of the saddle to scission evolution, and, in particular, the non-adiabatic effects near scission. Beyond mean-field approaches such as the time-dependent random-phase approximation (TDRPA) and stochastic mean-field methods have reached the point where they can be used for realistic applications. We review recent progresses in both techniques and applications to heavy-ion collision and fission. ; This work has been supported by the Australian Research Council Grant Nos. FT120100760 and DP160101254, and by the U.S. Department of Energy under Grant No. DESC0013847 with Vanderbilt University. Part of this research was undertaken with the assistance of resources from the National Computational Infrastructure (NCI), which is supported by the Australian Government

We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, HGF and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZC, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, CANARIE, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, ERDF, FP7, Horizon 2020 and Marie Sklodowska-Curie Actions, European Union; Investissements dAvenir Labex and Idex, ANR, Region Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; CERCA Programme Generalitat de Catalunya, Generalitat Valenciana, Spain; the Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. 51. ; Light-by-light scattering (γγ → γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb−1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 ± 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (γγ) → Pb(∗) + Pb(∗)γγ, for photon transverse energy ET > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ± 17 (syst.) nb, which is in agreement with the standard model predictions. ; BCKDF ; Canada Council ; CANARIE ; Australian Government ; Department of Industry, Innovation and Science ; Cooperative Research Centres (CRC) Programme ; Compute Canada ; FQRNT ; Ontario Innovation Trust, Canada ; EPLANET ; European Research Council (ERC) ; European Union (EU) ; FP7 ; Horizon 2020 ; French National Research Agency (ANR) ; Fondation Partager le Savoir, France ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Thales programme ; Aristeia programme ; Greek Ministry of Development-GSRT ; BSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; Minerva, Israel ; BRF, Norway ; Generalitat Valenciana ; Royal Society of London ; Leverhulme Trust

WOS: 000409235100017 ; Light-by-light scattering (gamma gamma -> gamma gamma) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 mu b(-1) of lead-lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 +/- 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (gamma gamma) -> Pb-(center dot) + Pb-(center dot) gamma gamma, for photon transverse energy E-T > 3 GeV, photon absolute pseudorapidity vertical bar eta vertical bar < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 +/- 24 (stat.) +/- 17 (syst.) nb, which is in agreement with the standard model predictions. ; BCKDF; Canada Council; CANARIE; CRCAustralian GovernmentDepartment of Industry, Innovation and ScienceCooperative Research Centres (CRC) Programme; Compute Canada; FQRNTFQRNT; Ontario Innovation Trust, Canada; EPLANET; ERCEuropean Research Council (ERC); ERDFEuropean Union (EU); FP7; Horizon 2020; Marie Sklodowska-Curie Actions, European UnionEuropean Union (EU); Investissements dAvenir Labex and IdexFrench National Research Agency (ANR); ANRRegion AuvergneFrench National Research Agency (ANR); Fondation Partager le Savoir, France; DFG, GermanyGerman Research Foundation (DFG); AvH Foundation, GermanyAlexander von Humboldt Foundation; Thales programme; Aristeia programme; EU-ESFEuropean Union (EU); Greek NSRFGreek Ministry of Development-GSRT; BSF, Israel; GIF, IsraelGerman-Israeli Foundation for Scientific Research and Development; Minerva, Israel; BRF, Norway; CERCA Programme Generalitat de Catalunya, Generalitat Valenciana, SpainGeneralitat Valenciana; Royal Society, United KingdomRoyal Society of London; Leverhulme Trust, United KingdomLeverhulme Trust ; We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, HGF and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZC, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, CANARIE, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, ERDF, FP7, Horizon 2020 and Marie Sklodowska-Curie Actions, European Union; Investissements dAvenir Labex and Idex, ANR, Region Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; CERCA Programme Generalitat de Catalunya, Generalitat Valenciana, Spain; the Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. 51.

Light-by-light scattering (gamma gamma -> gamma gamma) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 mu b(-1) of lead-lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 +/- 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (gamma gamma) -> Pb-(center dot) + Pb-(center dot) gamma gamma, for photon transverse energy E-T > 3 GeV, photon absolute pseudorapidity vertical bar eta vertical bar < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 +/- 24 (stat.) +/- 17 (syst.) nb, which is in agreement with the standard model predictions. ; ATLAS Collaboration, for complete list of authors see https://doi.org/10.1038/nphys4208 Funding: We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, HGF and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, CANARIE, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, ERDF, FP7, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d'Avenir Labex and Idex, ANR, Région Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; CERCA Programme Generalitat de Catalunya, Generalitat Valenciana, Spain; the Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. 51.

Quark gluon plasma (QGP) is a special state of nuclear matter where quarks and gluons behave like free particles. Recently, a number of investigations of this state with high temperature and/or density have been conducted using collisions of relativistic and ultra-relativistic heavy nuclei. It is accepted that depending on the temperature and density, 1st or the 2nd order phase transitions take place in hadron matter during the formation of QGP. Herein, we have modeled heavy ion collisions using a HIJING Monte-Carlo generator, taking into account the description of the 1st order phase transition as a probabilistic process. We analyzed the behavior of the fluctuations of the total (N = N+ – N–) and resultant (Q = N+ – N–) electric charges of the system. Different phases were introduced using the BDMPS (Baier – Dokshitzer – Mueller – Piegne – Schiff) model of parton energy loss during crossing through a dense nuclear medium.

BMWF (Austria) ; FWF (Austria) ; FNRS (Belgium) ; FWO (Belgium) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; MES (Bulgaria) ; CERN ; CAS (China) ; MoST (China) ; NSFC (China) ; COLCIENCIAS (Colombia) ; MSES (Croatia) ; RPF (Cyprus) ; MEYS (Czech Republic) ; MoER (Estonia) ; SF0690030s09 ; ERDF (Estonia) ; Academy of Finland (Finland) ; MEC (Finland) ; HIP (Finland) ; CEA (France) ; CNRS/IN2P3 (France) ; BMBF (Germany) ; DFG (Germany) ; HGF (Germany) ; GSRT (Greece) ; OTKA (Hungary) ; NKTH (Hungary) ; DAE (India) ; DST (India) ; IPM (Iran) ; SFI (Ireland) ; INFN (Italy) ; NRF (Korea) ; WCU (Korea) ; LAS (Lithuania) ; CINVESTAV (Mexico) ; CONACYT (Mexico) ; SEP (Mexico) ; UASLP-FAI (Mexico) ; MSI (New Zealand) ; PAEC (Pakistan) ; MSHE (Poland) ; NSC (Poland) ; FCT (Portugal) ; JINR (Armenia) ; JINR (Belarus) ; JINR (Georgia) ; JINR (Ukraine) ; JINR (Uzbekistan) ; MON (Russia) ; RosAtom (Russia) ; RAS (Russia) ; RFBR (Russia) ; MSTD (Serbia) ; SEIDI (Spain) ; CPAN (Spain) ; Swiss Funding Agencies (Switzerland) ; NSC (Taipei) ; TUBITAK (Turkey) ; TAEK (Turkey) ; NASU (Ukraine) ; STFC (United Kingdom) ; DOE (USA) ; NSF (USA) ; Marie-Curie programme and the European Research Council and EPLANET (European Union) ; Leventis Foundation ; A. P. Sloan Foundation ; Alexander von Humboldt Foundation ; Belgian Federal Science Policy Office ; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium) ; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium) ; Ministry of Education, Youth and Sports (MEYS) of Czech Republic ; Council of Science and Industrial Research, India ; Compagnia di San Paolo (Torino) ; HOMING PLUS programme of Foundation for Polish Science ; EU ; Regional Development Fund ; Thalis and Aristeia programmes ; EU-ESF ; Greek NSRF ; The production of (1S), (2S), and (3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 nb(-1) (pPb) and 5.4 pb(-1) (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval |y (CM)| < 1.93 in the nucleon-nucleon centre-of-mass frame. Their production is studied as a function of two measures of event activity, namely the charged-particle multiplicity measured in the pseudorapidity interval |eta| < 2.4, and the sum of transverse energy deposited at forward pseudorapidity, 4.0 < |eta| < 5.2. The cross sections normalized by their event activity integrated values, (nS)/aEuro(nS)aEuro parts per thousand, are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, (nS)/ (1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. The event activity integrated double ratios, [(nS)/ (1S)](pPb) /[(nS)/ (1S)](pp), are also measured and found to be 0.83 +/- 0.05 (stat.) +/- 0.05 (syst.) and 0.71 +/- 0.08 (stat.) +/- 0.09 (syst.) for (2S) and (3S), respectively.

Open Access: This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0).-- et al. ; The production of Y (1S), Y (2S), and Y (3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 nb−1 (pPb) and 5.4 pb−1 (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval |y CM| < 1.93 in the nucleon-nucleon centre-of-mass frame. Their production is studied as a function of two measures of event activity, namely the charged-particle multiplicity measured in the pseudorapidity interval |η| < 2.4, and the sum of transverse energy deposited at forward pseudorapidity, 4.0 < |η| < 5.2. The Y cross sections normalized by their event activity integrated values, Y (nS)/〈 Y (nS)〉, are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, Y (nS)/ Y (1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. The event activity integrated double ratios, [ Y (nS)/ Y (1S)]pPb /[ Y (nS)/ Y (1S)]pp, are also measured and found to be 0.83 ± 0.05 (stat.) ± 0.05 (syst.) and 0.71 ± 0.08 (stat.) ± 0.09 (syst.) for Y (2S) and Y (3S), respectively. ; Acknowledge support from: BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MEYS (Czech Republic); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation `a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation for Polish Science, cofinanced by EU, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF. ; Article funded by SCOAP3. ; Peer reviewed

Journal of High Energy Physics 2016.1 (2016): 006 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; Artículo escrito por un elevado número de autores, sólo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiera, y los autores pertenecientes a la UAM ; An analysis of dijet events in PbPb and pp collisions is performed to explore the properties of energy loss by partons traveling in a quark-gluon plasma. Data are collected at a nucleon-nucleon center-of-mass energy of 2.76 TeV at the LHC. The distribution of transverse momentum (pT) surrounding dijet systems is measured by selecting charged particles in different ranges of pT and at different angular cones of pseudorapidity and azimuth. The measurement is performed as a function of centrality of the PbPb collisions, the pT asymmetry of the jets in the dijet pair, and the distance parameter R used in the anti-kT jet clustering algorithm. In events with unbalanced dijets, PbPb collisions show an enhanced multiplicity in the hemisphere of the subleading jet, with the pT imbalance compensated by an excess of low-pT particles at large angles from the jet axes ; Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation `a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of the Foundation for Polish Science, cofinanced from European Union, Regional Development Fund; the OPUS programme of the National Science Center (Poland); the Compagnia di San Paolo (Torino); the Consorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF; the National Priorities Research Program by Qatar National Research Fund; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand); and the Welch Foundation, contract C-1845

BMWFW (Austria) ; FWF (Austria) ; FNRS (Belgium) ; FWO (Belgium) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; MES (Bulgaria) ; CERN ; CAS (China) ; MoST (China) ; NSFC (China) ; COLCIENCIAS (Colombia) ; MSES (Croatia) ; CSF (Croatia) ; RPF (Cyprus) ; MoER (Estonia) ; ERC IUT (Estonia) ; ERDF (Estonia) ; Academy of Finland (Finland) ; MEC (Finland) ; HIP (Finland) ; CEA (France) ; CNRS/IN2P3 (France) ; BMBF (Germany) ; DFG (Germany) ; HGF (Germany) ; GSRT (Greece) ; OTKA (Hungary) ; NIH (Hungary) ; DAE (India) ; DST (India) ; IPM (Iran) ; SFI (Ireland) ; INFN (Italy) ; MSIP (Republic of Korea) ; NRF (Republic of Korea) ; LAS (Lithuania) ; MOE (Malaysia) ; UM (Malaysia) ; CINVESTAV (Mexico) ; CONACYT (Mexico) ; SEP (Mexico) ; UASLP-FAI (Mexico) ; MBIE (New Zealand) ; PAEC (Pakistan) ; MSHE (Poland) ; NSC (Poland) ; FCT (Portugal) ; JINR (Dubna) ; MON (Russia) ; RosAtom (Russia) ; RAS (Russia) ; RFBR (Russia) ; MESTD (Serbia) ; SEIDI (Spain) ; CPAN (Spain) ; Swiss Funding Agencies (Switzerland) ; MST (Taipei) ; ThEPCenter (Thailand) ; IPST (Thailand) ; STAR (Thailand) ; NSTDA (Thailand) ; TUBITAK (Turkey) ; TAEK (Turkey) ; NASU (Ukraine) ; SFFR (Ukraine) ; STFC (United Kingdom) ; DOE (U.S.A.) ; NSF (U.S.A.) ; Austrian Federal Ministry of Science, Research and Economy ; Austrian Science Fund ; Belgian Fonds de la Recherche Scientifique ; Fonds voor Wetenschappelijk Onderzoek ; Bulgarian Ministry of Education and Science ; Chinese Academy of Sciences ; Ministry of Science and Technology ; National Natural Science Foundation of China ; Colombian Funding Agency (COLCIENCIAS) ; Croatian Ministry of Science, Education and Sport ; Croatian Science Foundation ; Research Promotion Foundation, Cyprus ; Ministry of Education and Research ; Estonian Research Council ; European Regional Development Fund, Estonia ; Academy of Finland ; Finnish Ministry of Education and Culture ; Helsinki Institute of Physics ; Institut National de Physique Nucleaire et de Physique des Particules / CNRS, France ; Commissariat a l'Energie Atomique et aux Energies Alternatives / CEA, France ; Bundesministerium fur Bildung and Forschung, Germany ; Deutsche Forschungsgemeinschaft, Germany ; Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany ; General Secretariat for Research and Technology, Greece ; National Scientific Research Foundation, Hungary ; National Innovation Office, Hungary ; Department of Atomic Energy, India ; Department of Science and Technology, India ; Institute for Studies in Theoretical Physics and Mathematics, Iran ; Science Foundation, Ireland ; Istituto Nazionale di Fisica Nucleare, Italy ; Ministry of Science, ICT and Future Planning ; National Research Foundation (NRF), Republic of Korea ; Lithuanian Academy of Sciences ; Ministry of Education ; University of Malaya (Malaysia) ; Mexican Funding Agency CINVESTAV ; Mexican Funding Agency CONACYT ; Mexican Funding Agency SEP ; Mexican Funding Agency UASLP-FAI ; Ministry of Business, Innovation and Employment, New Zealand ; Pakistan Atomic Energy Commission ; Ministry of Science and Higher Education, Poland ; National Science Centre, Poland ; Fundacao para a Ciencia e a Tecnologia, Portugal ; JINR, Dubna ; Ministry of Education and Science of the Russian Federation ; Federal Agency of Atomic Energy of the Russian Federation ; Russian Academy of Sciences ; Russian Foundation for Basic Research ; Ministry of Education, Science and Technological Development of Serbia ; Secretaria de Estado de Investigacion, Spain ; Desarrollo e Innovation, Spain ; Programa Consolider-Ingenio, Spain ; Swiss Funding Agency ETH Board ; Swiss Funding Agency ETH Zurich ; Swiss Funding Agency PSI ; Swiss Funding Agency SNF ; Swiss Funding Agency UniZH ; Swiss Funding Agency Canton Zurich ; Swiss Funding Agency SER ; Ministry of Science and Technology, Taipei ; Thailand Center of Excellence in Physics ; Institute for the Promotion of Teaching Science and Technology of Thailand ; Special Task Force for Activating Research ; National Science and Technology Development Agency of Thailand ; Scientific and Technical Research Council of Turkey ; Turkish Atomic Energy Authority ; National Academy of Sciences of Ukraine ; State Fund for Fundamental Researches, Ukraine ; Science and Technology Facilities Council, U.K. ; US Department of Energy ; US National Science Foundation ; Marie-Curie programme (European Union) ; European Research Council (European Union) ; EPLANET (European Union) ; Leventis Foundation ; A. P. Sloan Foundation ; Alexander von Humboldt Foundation ; Belgian Federal Science Policy Office ; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium) ; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium) ; Ministry of Education, Youth and Sports (MEYS) of the Czech Republic ; Council of Science and Industrial Research, India ; HOMING PLUS programme of the Foundation for Polish Science ; European Union ; Regional Development Fund ; OPUS programme of the National Science Center (Poland) ; Compagnia di San Paolo (Torino) ; Consorzio per la Fisica (Trieste) ; MIUR project (Italy) ; Thalis programme ; Aristeia programme ; EU-ESF ; Greek NSRF ; National Priorities Research Program by Qatar National Research Fund ; Rachadapisek Sompot Fund for Postdoctoral Fellowship ; Chulalongkorn University (Thailand) ; Welch Foundation ; Science and Technology Facilities Council ; Estonian Research Council: IUT23-4 ; Estonian Research Council: IUT23-6 ; MIUR project (Italy): 20108T4XTM ; Welch Foundation: C-1845 ; Science and Technology Facilities Council: ST/K003224/1 CMS Upgrades ; Science and Technology Facilities Council: ST/K001639/1 CMS Upgrades ; Science and Technology Facilities Council: ST/K001639/1 ; Science and Technology Facilities Council: ST/I003622/1 GRIDPP ; Science and Technology Facilities Council: ST/I005912/1 GRIDPP ; Science and Technology Facilities Council: ST/K003844/1 GRIDPP ; Science and Technology Facilities Council: ST/N000242/1 ; Science and Technology Facilities Council: ST/I003622/1 ; Science and Technology Facilities Council: ST/H000925/1 ; Science and Technology Facilities Council: ST/M004775/1 ; Science and Technology Facilities Council: ST/M005356/1 ; Science and Technology Facilities Council: ST/J005665/1 ; Science and Technology Facilities Council: ST/K003542/1 GRID PP ; Science and Technology Facilities Council: ST/K003542/1 GRIDPP ; Science and Technology Facilities Council: ST/L00609X/1 ; Science and Technology Facilities Council: GRIDPP ; Science and Technology Facilities Council: ST/M004775/1 GRIDPP ; Science and Technology Facilities Council: ST/K003844/1 ; Science and Technology Facilities Council: ST/L00609X/1 GRIDPP ; Science and Technology Facilities Council: ST/K003542/1 ; Science and Technology Facilities Council: CMS ; Science and Technology Facilities Council: ST/I005912/1 ; Science and Technology Facilities Council: ST/J004871/1 ; Science and Technology Facilities Council: ST/M005356/1 GRIDPP ; Science and Technology Facilities Council: ST/J004901/1 ; Science and Technology Facilities Council: ST/L005603/1 ; Science and Technology Facilities Council: PP/E000479/1 ; Science and Technology Facilities Council: ST/K001531/1 ; Science and Technology Facilities Council: ST/I000305/1 ; Science and Technology Facilities Council: ST/K001256/1 ; Science and Technology Facilities Council: ST/J50094X/1 ; Science and Technology Facilities Council: ST/J005479/1 ; Science and Technology Facilities Council: PP/E002803/1 ; Science and Technology Facilities Council: ST/H000925/2 ; Science and Technology Facilities Council: ST/N001273/1 ; Science and Technology Facilities Council: ST/N000250/1 ; Science and Technology Facilities Council: ST/M002020/1 ; An analysis of dijet events in PbPb and pp collisions is performed to explore the properties of energy loss by partons traveling in a quark-gluon plasma. Data are collected at a nucleon-nucleon center-of-mass energy of 2.76 TeV at the LHC. The distribution of transverse momentum (p(T)) surrounding dijet systems is measured by selecting charged particles in different ranges of p(T) and at different angular cones of pseudorapidity and azimuth. The measurement is performed as a function of centrality of the PbPb collisions, the p(T) asymmetry of the jets in the dijet pair, and the distance parameter R used in the anti-k(T) jet clustering algorithm. In events with unbalanced dijets, PbPb collisions show an enhanced multiplicity in the hemisphere of the subleading jet, with the p(T) imbalance compensated by an excess of low-p(T) particles at large angles from the jet axes.

BMWFW (Austria) ; FWF (Austria) ; FNRS (Belgium) ; FWO (Belgium) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; MES (Bulgaria) ; CERN ; CAS (China) ; MoST (China) ; NSFC (China) ; COLCIENCIAS (Colombia) ; MSES (Croatia) ; CSF (Croatia) ; RPF (Cyprus) ; SENESCYT (Ecuador) ; MoER (Estonia) ; ERC IUT (Estonia) ; ERDF (Estonia) ; Academy of Finland (Finland) ; MEC (Finland) ; HIP (Finland) ; CEA (France) ; CNRS/IN2P3 (France) ; BMBF (Germany) ; DFG (Germany) ; HGF (Germany) ; GSRT (Greece) ; OTKA (Hungary) ; NIH (Hungary) ; DAE (India) ; DST (India) ; IPM (Iran) ; SFI (Ireland) ; INFN (Italy) ; MSIP (Republic of Korea) ; NRF (Republic of Korea) ; LAS (Lithuania) ; MOE (Malaysia) ; UM (Malaysia) ; BUAP (Mexico) ; CINVESTAV (Mexico) ; CONACYT (Mexico) ; LNS (Mexico) ; SEP (Mexico) ; UASLP-FAI (Mexico) ; MBIE (New Zealand) ; PAEC (Pakistan) ; MSHE (Poland) ; NSC (Poland) ; FCT (Portugal) ; JINR (Dubna) ; MON (Russia) ; RosAtom (Russia) ; RAS (Russia) ; RFBR (Russia) ; MESTD (Serbia) ; SEIDI (Spain) ; CPAN (Spain) ; Swiss Funding Agencies (Switzerland) ; MST (Taipei) ; ThEPCenter (Thailand) ; IPST (Thailand) ; STAR (Thailand) ; NSTDA (Thailand) ; TUBITAK (Turkey) ; TAEK (Turkey) ; NASU (Ukraine) ; SFFR (Ukraine) ; STFC (United Kingdom) ; DOE (U.S.A.) ; NSF (U.S.A.) ; Marie-Curie programme and the European Research Council and EPLANET (European Union) ; Leventis Foundation ; A. P. Sloan Foundation ; Alexander von Humboldt Foundation ; Belgian Federal Science Policy Office ; Fonds pour la Formation a a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium) ; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium) ; Ministry of Education, Youth and Sports (MEYS) of the Czech Republic ; Council of Science and Industrial Research, India ; HOMING PLUS programme of the Foundation for Polish Science ; European Union ; Regional Development Fund ; Mobility Plus programme of the Ministry of Science and Higher Education ; National Science Center (Poland) ; Thalis and Aristeia programmes - EU-ESF ; Greek NSRF ; National Priorities Research Program by Qatar National Research Fund ; Programa Clarin-COFUND del Principado de Asturias ; Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University ; Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand) ; Welch Foundation ; Science and Technology Facilities Council ; National Science Center (Poland): 2014/14/M/ST2/00428 ; National Science Center (Poland): 2013/11/B/ST2/04202 ; National Science Center (Poland): 2014/13/B/ST2/02543 ; National Science Center (Poland): 2014/15/B/ST2/03998 ; National Science Center (Poland): 2012/07/E/ST2/01406 ; Welch Foundation: C-1845 ; Science and Technology Facilities Council: ST/N001273/1 ; Science and Technology Facilities Council: ST/K003542/1 GRID PP ; Science and Technology Facilities Council: ST/K001639/1 CMS Upgrades ; Science and Technology Facilities Council: ST/N000250/1 ; Science and Technology Facilities Council: ST/J005479/1 ; Science and Technology Facilities Council: PP/E002803/1 ; Science and Technology Facilities Council: PP/E000479/1 ; Science and Technology Facilities Council: ST/K003224/1 CMS Upgrades ; Science and Technology Facilities Council: ST/H000925/2 ; Science and Technology Facilities Council: ST/K003542/1 ; Science and Technology Facilities Council: ST/K003542/1 GRIDPP ; Science and Technology Facilities Council: ST/J004871/1 ; Science and Technology Facilities Council: ST/K001256/1 ; Science and Technology Facilities Council: ST/L005603/1 ; Science and Technology Facilities Council: ST/K001639/1 ; Science and Technology Facilities Council: ST/H000925/1 ; Science and Technology Facilities Council: ST/M004775/1 ; Science and Technology Facilities Council: ST/M004775/1 GRIDPP ; Science and Technology Facilities Council: ST/M002020/1 ; Science and Technology Facilities Council: ST/K001531/1 ; Science and Technology Facilities Council: ST/N000242/1 ; Science and Technology Facilities Council: GRIDPP ; Science and Technology Facilities Council: CMS ; Science and Technology Facilities Council: ST/I003622/1 GRIDPP ; Science and Technology Facilities Council: ST/I003622/1 ; Science and Technology Facilities Council: ST/I000305/1 ; Interactions between jets and the quark-gluon plasma produced in heavy ion collisions are studied via the angular distributions of summed charged-particle transverse momenta (p(T)) with respect to both the leading and subleading jet axes in high-p(T) dijet events. The contributions of charged particles in different momentum ranges to the overall event p(T) balance are decomposed into short-range jet peaks and a long-range azimuthal asymmetry in charged-particle p(T). The results for PbPb collisions are compared to those in pp collisions using data collected in 2011 and 2013, at collision energy root s(NN) = 2.76 TeV with integrated luminosities of 166 mu b(-1) and 5.3 pb(-1), respectively, by the CMS experiment at the LHC. Measurements are presented as functions of PbPb collision centrality, charged-particle p(T), relative azimuth, and radial distance from the jet axis for balanced and unbalanced dijets.