Hypertriton Production in p-Pb Collisions at √sNN = 5.02 TeV

The study of nuclei and antinuclei production has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. The first measurement of the production of ${\rm ^{3}_{\Lambda}\rm H}$ in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV is presented in this Letter. Its production yield measured in the rapidity interval -1 < y < 0 for the 40% highest multiplicity p-Pb collisions is ${\rm d} N /{\rm d} y =[\mathrm{6.3 \pm 1.8 (stat.) \pm 1.2 (syst.) ] \times 10^{-7}}$. The measurement is compared with the expectations of statistical hadronisation and coalescence models, which describe the nucleosynthesis in hadronic collisions. These two models predict very different yields of the hypertriton in small collision systems such as p-Pb and therefore the measurement of ${\rm d} N /{\rm d} y$ is crucial to distinguish between them. The precision of this measurement leads to the exclusion with a significance larger than 6$\sigma$ of some configurations of the statistical hadronisation, thus constraining the production mechanism of loosely bound states

Direct observation of the dead-cone effect in quantum chromodynamics

In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD). These partons subsequently emit further partons in a process that can be described as a parton shower, which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass m_Q and energy E, within a cone of angular size m_Q/E around the emitter. Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics

K0SK0S and K0SK± femtoscopy in pp collisions at √s = 5.02 and 13 TeV

Femtoscopic correlations with the particle pair combinations (KSKS0)-K-0 and (KSK +/-)-K-0 are studied in pp collisions at root s= 5.02 and 13 TeV by the ALICE experiment. At both energies, boson source parameters are extracted for both pair combinations, by fitting models based on Gaussian size distributions of the sources, to the measured two-particle correlation functions. The interaction model used for the (KSKS0)-K-0 analysis includes quantum statistics and strong final-state interactions through the f(0) (980) and a(0) (980) resonances. The model used for the (KSK +/-)-K-0 analysis includes only the final-state interaction through the a(0) resonance. Source parameters extracted in the present work are compared with published values from pp collisions at root s = 7 TeV and the different pair combinations are found to be consistent. From the observation that the strength of the (KSKS0)-K-0 correlations is significantly greater than the strength of the (KSK +/-)-K-0 correlations, the new results are compatible with the a(0) resonance being a tetraquark state of the form (q(1), (q(2)) over bar, s, (s) over bar), where q(1) and q(2) are uor d quarks. (C) 2022 European Organization for Nuclear Research, ALICE. Published by Elsevier B.V

Inclusive J / ψ production at midrapidity in pp collisions at √s=13 TeV

open1030siAcknowledgements We wish to thank Mathias Butenschoen, Vincent Cheung, Bernd A. Kniehl, Artem V. Lipatov, Yan-Qing Ma, Raju Venugopalan and Ramona Vogt for kindly providing their calculations. The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable contributions to the construction of the experiment and the CERN accelerator teams for the outstanding performance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources and support provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration. The ALICE Collaboration acknowledges the following funding agencies for their support in building and running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation (ANSL), State Committee of Science and World Federation of Scientists (WFS), Armenia; Austrian Academy of Sciences, Austrian Science Fund (FWF): [M 2467-N36] and Nationalstiftung für Forschung, Technologie und Entwicklung, Austria; Ministry of Communications and High Technologies, National Nuclear Research Center, Azerbaijan; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (Finep), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Universidade Federal do Rio Grande do Sul (UFRGS), Brazil; Ministry of Education of China (MOEC) , Ministry of Science and Technology of China (MSTC) and National Natural Science Foundation of China (NSFC), China; Ministry of Science and Education and Croatian Science Foundation, Croatia; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Cubaenergía, Cuba; Ministry of Education, Youth and Sports of the Czech Republic, Czech Republic; The Danish Council for Independent Research | Natural Sciences, the VILLUM FONDEN and Danish National Research Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP), Finland; Commissariat à l’Energie Atomique (CEA) and Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) and Centre National de la Recherche Scientifique (CNRS), France; Bundesministerium für Bildung und Forschung (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany; General Secretariat for Research and Technology, Ministry of Education, Research and Religions, Greece; National Research, Development and Innovation Office, Hungary; Department of Atomic Energy Government of India (DAE), Department of Science and Technology, Government of India (DST), University Grants Commission, Government of India (UGC) and Council of Scientific and Industrial Research (CSIR), India; Indonesian Institute of Science, Indonesia; Istituto Nazionale di Fisica Nucleare (INFN), Italy; Institute for Innovative Science and Technology , Nagasaki Institute of Applied Science (IIST), Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and Japan Society for the Promotion of Science (JSPS) KAKENHI, Japan; Consejo Nacional de Ciencia (CONACYT) y Tecnología, through Fondo de Cooperación Internacional en Ciencia y Tecnología (FONCICYT) and Dirección General de Asuntos del Personal Academico (DGAPA), Mexico; Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands; The Research Council of Norway, Norway; Commission on Science and Technology for Sustainable Development in the South (COMSATS), Pakistan; Pontificia Universidad Católica del Perú, Peru; Ministry of Education and Science, National Science Centre and WUT ID-UB, Poland; Korea Institute of Science and Technology Information and National Research Foundation of Korea (NRF), Republic of Korea; Ministry of Education and Scientific Research, Institute of Atomic Physics and Ministry of Research and Innovation and Institute of Atomic Physics, Romania; Joint Institute for Nuclear Research (JINR), Ministry of Education and Science of the Russian Federation, National Research Centre Kurchatov Institute, Russian Science Foundation and Russian Foundation for Basic Research, Russia; Ministry of Education, Science, Research and Sport of the Slovak Republic, Slovakia; National Research Foundation of South Africa, South Africa; Swedish Research Council (VR) and Knut and Alice Wallenberg Foundation (KAW), Sweden; European Organization for Nuclear Research, Switzerland; Suranaree University of Technology (SUT), National Science and Technology Development Agency (NSDTA) and Office of the Higher Education Commission under NRU project of Thailand, Thailand; Turkish Energy, Nuclear and Mineral Research Agency (TENMAK), Turkey; National Academy of Sciences of Ukraine, Ukraine; Science and Technology Facilities Council (STFC), United Kingdom; National Science Foundation of the United States of America (NSF) and United States Department of Energy, Office of Nuclear Physics (DOE NP), United States of America. In addition, individual groups and members have received support from Horizon 2020 and Marie Skłodowska Curie Actions, European Union.We report on the inclusive J / ψ production cross section measured at the CERN Large Hadron Collider in proton–proton collisions at a center-of-mass energy s=13&nbsp;TeV. The J / ψ mesons are reconstructed in the e +e - decay channel and the measurements are performed at midrapidity (| y| &lt; 0.9) in the transverse-momentum interval 0 &lt; pT&lt; 40 GeV/c, using a minimum-bias data sample corresponding to an integrated luminosity Lint=32.2nb-1 and an Electromagnetic Calorimeter triggered data sample with Lint=8.3pb-1. The pT-integrated J / ψ production cross section at midrapidity, computed using the minimum-bias data sample, is dσ/dy|y=0=8.97±0.24(stat)±0.48(syst)±0.15(lumi)μb. An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and pT-differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models.openAcharya S.; Adamova D.; Adler A.; Aglieri Rinella G.; Agnello M.; Agrawal N.; Ahammed Z.; Ahmad S.; Ahn S.U.; Ahuja I.; Akbar Z.; Akindinov A.; Al-Turany M.; Alam S.N.; Aleksandrov D.; Alessandro B.; Alfanda H.M.; Alfaro Molina R.; Ali B.; Ali Y.; Alici A.; Alizadehvandchali N.; Alkin A.; Alme J.; Alt T.; Altenkamper L.; Altsybeev I.; Anaam M.N.; Andrei C.; Andreou D.; Andronic A.; Angeletti M.; Anguelov V.; Antinori F.; Antonioli P.; Anuj C.; Apadula N.; Aphecetche L.; Appelshauser H.; Arcelli S.; Arnaldi R.; Arsene I.C.; Arslandok M.; Augustinus A.; Averbeck R.; Aziz S.; Azmi M.D.; Badala A.; Baek Y.W.; Bai X.; Bailhache R.; Bailung Y.; Bala R.; Balbino A.; Baldisseri A.; Balis B.; Ball M.; Banerjee D.; Barbera R.; Barioglio L.; Barlou M.; Barnafoldi G.G.; Barnby L.S.; Barret V.; Bartels C.; Barth K.; Bartsch E.; Baruffaldi F.; Bastid N.; Basu S.; Batigne G.; Batyunya B.; Bauri D.; Alba J.L.B.; Bearden I.G.; Beattie C.; Belikov I.; Bell Hechavarria A.D.C.; Bellini F.; Bellwied R.; Belokurova S.; Belyaev V.; Bencedi G.; Beole S.; Bercuci A.; Berdnikov Y.; Berdnikova A.; Bergmann L.; Besoiu M.G.; Betev L.; Bhaduri P.P.; Bhasin A.; Bhat I.R.; Bhat M.A.; Bhattacharjee B.; Bhattacharya P.; Bianchi L.; Bianchi N.; Bielcik J.; Bielcikova J.; Biernat J.; Bilandzic A.; Biro G.; Biswas S.; Blair J.T.; Blau D.; Blidaru M.B.; Blume C.; Boca G.; Bock F.; Bogdanov A.; Boi S.; Bok J.; Boldizsar L.; Bolozdynya A.; Bombara M.; Bond P.M.; Bonomi G.; Borel H.; Borissov A.; Bossi H.; Botta E.; Bratrud L.; Braun-Munzinger P.; Bregant M.; Broz M.; Bruno G.E.; Buckland M.D.; Budnikov D.; Buesching H.; Bufalino S.; Bugnon O.; Buhler P.; Buthelezi Z.; Butt J.B.; Bylinkin A.; Bysiak S.A.; Cai M.; Caines H.; Caliva A.; Calvo Villar E.; Camacho J.M.M.; Camacho R.S.; Camerini P.; Canedo F.D.M.; Carnesecchi F.; Caron R.; Castillo Castellanos J.; Casula E.A.R.; Catalano F.; Ceballos Sanchez C.; Chakraborty P.; Chandra S.; Chapeland S.; Chartier M.; Chattopadhyay S.; Chattopadhyay S.; Chauvin A.; Chavez T.G.; Cheng T.; Cheshkov C.; Cheynis B.; Chibante Barroso V.; Chinellato D.D.; Cho S.; Chochula P.; Christakoglou P.; Christensen C.H.; Christiansen P.; Chujo T.; Cicalo C.; Cifarelli L.; Cindolo F.; Ciupek M.R.; Clai G.; Cleymans J.; Colamaria F.; Colburn J.S.; Colella D.; Collu A.; Colocci M.; Concas M.; Conesa Balbastre G.; Conesa del Valle Z.; Contin G.; Contreras J.G.; Coquet M.L.; Cormier T.M.; Cortese P.; Cosentino M.R.; Costa F.; Costanza S.; Crochet P.; Cruz-Torres R.; Cuautle E.; Cui P.; Cunqueiro L.; Dainese A.; Danisch M.C.; Danu A.; Das I.; Das P.; Das P.; Das S.; Dash S.; De S.; De Caro A.; de Cataldo G.; De Cilladi L.; de Cuveland J.; De Falco A.; De Gruttola D.; De Marco N.; De Martin C.; De Pasquale S.; Deb S.; Degenhardt H.F.; Deja K.R.; Stritto L.D.; Delsanto S.; Deng W.; Dhankher P.; Di Bari D.; Di Mauro A.; Diaz R.A.; Dietel T.; Ding Y.; Divia R.; Dixit D.U.; Djuvsland O.; Dmitrieva U.; Do J.; Dobrin A.; Donigus B.; Dordic O.; Dubey A.K.; Dubla A.; Dudi S.; Dukhishyam M.; Dupieux P.; Dzalaiova N.; Eder T.M.; Ehlers R.J.; Eikeland V.N.; Eisenhut F.; Elia D.; Erazmus B.; Ercolessi F.; Erhardt F.; Erokhin A.; Ersdal M.R.; Espagnon B.; Eulisse G.; Evans D.; Evdokimov S.; Fabbietti L.; Faggin M.; Faivre J.; Fan F.; Fantoni A.; Fasel M.; Fecchio P.; Feliciello A.; Feofilov G.; Fernandez Tellez A.; Ferrero A.; Ferretti A.; Feuillard V.J.G.; Figiel J.; Filchagin S.; Finogeev D.; Fionda F.M.; Fiorenza G.; Flor F.; Flores A.N.; Foertsch S.; Foka P.; Fokin S.; Fragiacomo E.; Frajna E.; Fuchs U.; Funicello N.; Furget C.; Furs A.; Gaardhoje J.J.; Gagliardi M.; Gago A.M.; Gal A.; Galvan C.D.; Ganoti P.; Garabatos C.; Garcia J.R.A.; Garcia-Solis E.; Garg K.; Gargiulo C.; Garibli A.; Garner K.; Gasik P.; Gauger E.F.; Gautam A.; Gay Ducati M.B.; Germain M.; Ghosh P.; Ghosh S.K.; Giacalone M.; Gianotti P.; Giubellino P.; Giubilato P.; Glaenzer A.M.C.; Glassel P.; Goh D.J.Q.; Gonzalez V.; Gonzalez-Trueba L.H.; Gorbunov S.; Gorgon M.; Gorlich L.; Gotovac S.; Grabski V.; Graczykowski L.K.; Greiner L.; Grelli A.; Grigoras C.; Grigoriev V.; Grigoryan S.; Groettvik O.S.; Grosa F.; Grosse-Oetringhaus J.F.; Grosso R.; Guardiano G.G.; Guernane R.; Guilbaud M.; Gulbrandsen K.; Gunji T.; Guo W.; Gupta A.; Gupta R.; Guzman S.P.; Gyulai L.; Habib M.K.; Hadjidakis C.; Halimoglu G.; Hamagaki H.; Hamar G.; Hamid M.; Hannigan R.; Haque M.R.; Harlenderova A.; Harris J.W.; Harton A.; Hasenbichler J.A.; Hassan H.; Hatzifotiadou D.; Hauer P.; Havener L.B.; Hayashi S.; Heckel S.T.; Hellbar E.; Helstrup H.; Herman T.; Hernandez E.G.; Herrera Corral G.; Herrmann F.; Hetland K.F.; Hillemanns H.; Hills C.; Hippolyte B.; Hofman B.; Hohlweger B.; Honermann J.; Hong G.H.; Horak D.; Hornung S.; Horzyk A.; Hosokawa R.; Hou Y.; Hristov P.; Hughes C.; Huhn P.; Humanic T.J.; Hushnud H.; Husova L.A.; Hutson A.; Hutter D.; Iddon J.P.; Ilkaev R.; Ilyas H.; Inaba M.; Innocenti G.M.; Ippolitov M.; Isakov A.; Islam M.S.; Ivanov M.; Ivanov V.; Izucheev V.; Jablonski M.; Jacak B.; Jacazio N.; Jacobs P.M.; Jadlovska S.; Jadlovsky J.; Jaelani S.; Jahnke C.; Jakubowska M.J.; Jalotra A.; Janik M.A.; Janson T.; Jercic M.; Jevons O.; Jimenez A.A.P.; Jonas F.; Jones P.G.; Jowett J.M.; Jung J.; Jung M.; Junique A.; Jusko A.; Kaewjai J.; Kalinak P.; Kalteyer A.S.; Kalweit A.; Kaplin V.; Kar S.; Karasu Uysal A.; Karatovic D.; Karavichev O.; Karavicheva T.; Karczmarczyk P.; Karpechev E.; Kazantsev A.; Kebschull U.; Keidel R.; Keijdener D.L.D.; Keil M.; Ketzer B.; Khabanova Z.; Khan A.M.; Khan S.; Khanzadeev A.; Kharlov Y.; Khatun A.; Khuntia A.; Kileng B.; Kim B.; Kim C.; Kim D.J.; Kim E.J.; Kim J.; Kim J.S.; Kim J.; Kim J.; Kim J.; Kim M.; Kim S.; Kim T.; Kirsch S.; Kisel I.; Kiselev S.; Kisiel A.; Kitowski J.P.; Klay J.L.; Klein J.; Klein S.; Klein-Bosing C.; 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Lopez X.; Lopez Torres E.; Luhder J.R.; Lunardon M.; Luparello G.; Ma Y.G.; Maevskaya A.; Mager M.; Mahmoud T.; Maire A.; Malaev M.; Malik N.M.; Malik Q.W.; Malinina L.; Mal'Kevich D.; Mallick N.; Malzacher P.; Mandaglio G.; Manko V.; Manso F.; Manzari V.; Mao Y.; Mares J.; Margagliotti G.V.; Margotti A.; Marin A.; Markert C.; Marquard M.; Martin N.A.; Martinengo P.; Martinez J.L.; Martinez M.I.; Martinez Garcia G.; Masciocchi S.; Masera M.; Masoni A.; Massacrier L.; Mastroserio A.; Mathis A.M.; Matonoha O.; Matuoka P.F.T.; Matyja A.; Mayer C.; Mazuecos A.L.; Mazzaschi F.; Mazzilli M.; Mazzoni M.A.; Mdhluli J.E.; Mechler A.F.; Meddi F.; Melikyan Y.; Menchaca-Rocha A.; Meninno E.; Menon A.S.; Meres M.; Mhlanga S.; Miake Y.; Micheletti L.; Migliorin L.C.; Mihaylov D.L.; Mikhaylov K.; Mishra A.N.; Miskowiec D.; Modak A.; Mohanty A.P.; Mohanty B.; Mohisin Khan M.; Molander M.A.; Moravcova Z.; Mordasini C.; Moreira De Godoy D.A.; Moreno L.A.P.; Morozov I.; Morsch A.; Mrnjavac T.; Muccifora V.; 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Slupecki M.; Smirnov N.; Snellings R.J.M.; Soncco C.; Song J.; Songmoolnak A.; Soramel F.; Sorensen S.; Sputowska I.; Stachel J.; Stan I.; Steffanic P.J.; Stiefelmaier S.F.; Stocco D.; Storehaug I.; Storetvedt M.M.; Stylianidis C.P.; Suaide A.A.P.; Sugitate T.; Suire C.; Sukhanov M.; Suljic M.; Sultanov R.; Sumbera M.; Sumberia V.; Sumowidagdo S.; Swain S.; Szabo A.; Szarka I.; Tabassam U.; Taghavi S.F.; Taillepied G.; Takahashi J.; Tambave G.J.; Tang S.; Tang Z.; Tapia Takaki J.D.; Tarhini M.; Tarzila M.G.; Tauro A.; Tejeda Munoz G.; Telesca A.; Terlizzi L.; Terrevoli C.; Tersimonov G.; Thakur S.; Thomas D.; Tieulent R.; Tikhonov A.; Timmins A.R.; Tkacik M.; Toia A.; Topilskaya N.; Toppi M.; Torales-Acosta F.; Tork T.; Torres S.R.; Trifiro A.; Tripathy S.; Tripathy T.; Trogolo S.; Trubnikov V.; Trzaska W.H.; Trzcinski T.P.; Trzeciak B.A.; Tumkin A.; Turrisi R.; Tveter T.S.; Ullaland K.; Uras A.; Urioni M.; Usai G.L.; Vala M.; Valle N.; Vallero S.; van der Kolk N.; van Doremalen L.V.R.; van Leeuwen M.; Vande Vyvre P.; Varga D.; Varga Z.; Varga-Kofarago M.; Vargas A.; Vasileiou M.; Vasiliev A.; Vazquez Doce O.; Vechernin V.; Vercellin E.; Vergara Limon S.; Vermunt L.; Vertesi R.; Verweij M.; Vickovic L.; Vilakazi Z.; Villalobos Baillie O.; Vino G.; Vinogradov A.; Virgili T.; Vislavicius V.; Vodopyanov A.; Volkel B.; Volkl M.A.; Voloshin K.; Voloshin S.A.; Volpe G.; von Haller B.; Vorobyev I.; Voscek D.; Vozniuk N.; Vrlakova J.; Wagner B.; Wang C.; Wang D.; Weber M.; Weelden R.J.G.V.; Wegrzynek A.; Wenzel S.C.; Wessels J.P.; Wiechula J.; Wikne J.; Wilk G.; Wilkinson J.; Willems G.A.; Windelband B.; Winn M.; Witt W.E.; Wright J.R.; Wu W.; Wu Y.; Xu R.; Yadav A.K.; Yalcin S.; Yamaguchi Y.; Yamakawa K.; Yang S.; Yano S.; Yin Z.; Yokoyama H.; Yoo I.-K.; Yoon J.H.; Yuan S.; Yuncu A.; Zaccolo V.; Zampolli C.; Zanoli H.J.C.; Zardoshti N.; Zarochentsev A.; Zavada P.; Zaviyalov N.; Zhalov M.; Zhang B.; Zhang S.; Zhang X.; Zhang Y.; Zherebchevskii V.; Zhi Y.; Zhigareva N.; Zhou D.; Zhou Y.; Zhu J.; Zhu Y.; Zichichi A.; Zinovjev G.; Zurlo N.Acharya S.; Adamova D.; Adler A.; Aglieri Rinella G.; Agnello M.; Agrawal N.; Ahammed Z.; Ahmad S.; Ahn S.U.; Ahuja I.; Akbar Z.; Akindinov A.; Al-Turany M.; Alam S.N.; Aleksandrov D.; Alessandro B.; Alfanda H.M.; Alfaro Molina R.; Ali B.; Ali Y.; Alici A.; Alizadehvandchali N.; Alkin A.; Alme J.; Alt T.; Altenkamper L.; Altsybeev I.; Anaam M.N.; Andrei C.; Andreou D.; Andronic A.; Angeletti M.; Anguelov V.; Antinori F.; Antonioli P.; Anuj C.; Apadula N.; Aphecetche L.; Appelshauser H.; Arcelli S.; Arnaldi R.; Arsene I.C.; Arslandok M.; Augustinus A.; Averbeck R.; Aziz S.; Azmi M.D.; Badala A.; Baek Y.W.; Bai X.; Bailhache R.; Bailung Y.; Bala R.; Balbino A.; Baldisseri A.; Balis B.; Ball M.; Banerjee D.; Barbera R.; Barioglio L.; Barlou M.; Barnafoldi G.G.; Barnby L.S.; Barret V.; Bartels C.; Barth K.; Bartsch E.; Baruffaldi F.; Bastid N.; Basu S.; Batigne G.; Batyunya B.; Bauri D.; Alba J.L.B.; Bearden I.G.; Beattie C.; Belikov I.; Bell Hechavarria A.D.C.; Bellini F.; Bellwied R.; Belokurova S.; Belyaev V.; Bencedi G.; Beole S.; Bercuci A.; Berdnikov Y.; Berdnikova A.; Bergmann L.; Besoiu M.G.; Betev L.; Bhaduri P.P.; Bhasin A.; Bhat I.R.; Bhat M.A.; Bhattacharjee B.; Bhattacharya P.; Bianchi L.; Bianchi N.; Bielcik J.; Bielcikova J.; Biernat J.; Bilandzic A.; Biro G.; Biswas S.; Blair J.T.; Blau D.; Blidaru M.B.; Blume C.; Boca G.; Bock F.; Bogdanov A.; Boi S.; Bok J.; Boldizsar L.; Bolozdynya A.; Bombara M.; Bond P.M.; Bonomi G.; Borel H.; Borissov A.; Bossi H.; Botta E.; Bratrud L.; Braun-Munzinger P.; Bregant M.; Broz M.; Bruno G.E.; Buckland M.D.; Budnikov D.; Buesching H.; Bufalino S.; Bugnon O.; Buhler P.; Buthelezi Z.; Butt J.B.; Bylinkin A.; Bysiak S.A.; Cai M.; Caines H.; Caliva A.; Calvo Villar E.; Camacho J.M.M.; Camacho R.S.; Camerini P.; Canedo F.D.M.; Carnesecchi F.; Caron R.; Castillo Castellanos J.; Casula E.A.R.; Catalano F.; Ceballos Sanchez C.; Chakraborty P.; Chandra S.; Chapeland S.; Chartier M.; Chattopadhyay S.; Chattopadhyay S.; Chauvin A.; Chavez T.G.; Cheng T.; Cheshkov C.; Cheynis B.; Chibante Barroso V.; Chinellato D.D.; Cho S.; Chochula P.; Christakoglou P.; Christensen C.H.; Christiansen P.; Chujo T.; Cicalo C.; Cifarelli L.; Cindolo F.; Ciupek M.R.; Clai G.; Cleymans J.; Colamaria F.; Colburn J.S.; Colella D.; Collu A.; Colocci M.; Concas M.; Conesa Balbastre G.; Conesa del Valle Z.; Contin G.; Contreras J.G.; Coquet M.L.; Cormier T.M.; Cortese P.; Cosentino M.R.; Costa F.; Costanza S.; Crochet P.; Cruz-Torres R.; Cuautle E.; Cui P.; Cunqueiro L.; Dainese A.; Danisch M.C.; Danu A.; Das I.; Das P.; Das P.; Das S.; Dash S.; De S.; De Caro A.; de Cataldo G.; De Cilladi L.; de Cuveland J.; De Falco A.; De Gruttola D.; De Marco N.; De Martin C.; De Pasquale S.; Deb S.; Degenhardt H.F.; Deja K.R.; Stritto L.D.; Delsanto S.; Deng W.; Dhankher P.; Di Bari D.; Di Mauro A.

Polarization of Λ and Λ¯ Hyperons along the Beam Direction in Pb-Pb Collisions at √sNN = 5.02 TeV

The polarization of the Lambda and (Lambda) over bar hyperons along the beam (z) direction, P-z, has been measured in Pb-Pb collisions at root s(NN) = 5.02 TeV recorded with ALICE at the Large Hadron Collider (LHC). The main contribution to P-z comes from elliptic flow-induced vorticity and can be characterized by the second Fourier sine coefficient P-z,P-s2 = &lt; P-z sin(2 phi - 2 Psi(2))&gt;, where phi is the hyperon azimuthal emission angle and Psi(2) is the elliptic flow plane angle. We report the measurement of P-z,P-s2 for different collision centralities and in the 30%-50% centrality interval as a function of the hyperon transverse momentum and rapidity. The P-z,P-s2 is positive similarly as measured by the STAR Collaboration in Au-Au collisions at root s(NN) = 200 GeV, with somewhat smaller amplitude in the semicentral collisions. This is the first experimental evidence of a nonzero hyperon P-z in Pb-Pb collisions at the LHC. The comparison of the measured P-z,P-s2 with the hydrodynamic model calculations shows sensitivity to the competing contributions from thermal and the recently found shear-induced vorticity, as well as to whether the polarization is acquired at the quark-gluon plasma or the hadronic phase

Charged-particle multiplicity fluctuations in Pb–Pb collisions at √sNN = 2.76 TeV

Measurements of event-by-event fluctuations of charged-particle multiplicities in Pb–Pb collisions at √sNN = 2.76 TeV using the ALICE detector at the CERN Large Hadron Collider (LHC) are presented in the pseudorapidity range |η|<0.8 and transverse momentum 0.2<pT<2.0 GeV/c. The amplitude of the fluctuations is expressed in terms of the variance normalized by the mean of the multiplicity distribution. The η and pT dependences of the fluctuations and their evolution with respect to collision centrality are investigated. The multiplicity fluctuations tend to decrease from peripheral to central collisions. The results are compared to those obtained from HIJING and AMPT Monte Carlo event generators as well as to experimental data at lower collision energies. Additionally, the measured multiplicity fluctuations are discussed in the context of the isothermal compressibility of the high-density strongly-interacting system formed in central Pb–Pb collisions.publishedVersio

Investigating charm production and fragmentation via azimuthal correlations of prompt D mesons with charged particles in pp collisions at root s=13 TeV

Angular correlations of heavy-flavour and charged particles in high-energy proton-proton collisions are sensitive to the production mechanisms of heavy quarks and to their fragmentation as well as hadronisation processes. The measurement of the azimuthal-correlation function of prompt D mesons with charged particles in proton-proton collisions at a centre-of-mass energy of root s = 13 TeV with the ALICE detector is reported, considering D-0, D+, and D*(+) mesons in the transverse-momentum interval 3 0.3 GeV/c and pseudorapidity vertical bar eta vertical bar < 0.8. This measurement has an improved precision and provides an extended transverse-momentum coverage compared to previous ALICE measurements at lower energies. The study is also performed as a function of the charged-particle multiplicity, showing no modifications of the correlation function with multiplicity within uncertainties. The properties and the transverse-momentum evolution of the near- and awayside correlation peaks are studied and compared with predictions from various Monte Carlo event generators. Among those considered, PYTHIA8 and POWHEG+PYTHIA8 provide the best description of the measured observables. The obtained results can provide guidance on tuning the generators

Study of very forward energy and its correlation with particle production at midrapidity in pp and p-Pb collisions at the LHC

The energy deposited at very forward rapidities (very forward energy) is a powerful tool for characterising proton fragmentation in pp and p-Pb collisions. The correlation of very forward energy with particle production at midrapidity provides direct insights into the initial stages and the subsequent evolution of the collision. Furthermore, the correlation with the production of particles with large transverse momenta at midrapidity provides information complementary to the measurements of the underlying event, which are usually interpreted in the framework of models implementing centrality-dependent multiple parton interactions. Results about very forward energy, measured by the ALICE zero degree calorimeters (ZDCs), and its dependence on the activity measured at midrapidity in pp collisions at √s = 13 TeV and in p-Pb collisions at √sNN = 8.16 TeV are discussed. The measurements performed in pp collisions are compared with the expectations of three hadronic interaction event generators: PYTHIA 6 (Perugia 2011 tune), PYTHIA 8 (Monash tune), and EPOS LHC. These results provide new constraints on the validity of models in describing the beam remnants at very forward rapidities, where perturbative QCD cannot be used

Inclusive J/psi production at midrapidity in pp collisions at root s=13 Tev

We report on the inclusive J/psi production cross section measured at the CERN Large Hadron Collider in proton-proton collisions at a center-of-mass energy root s = 13 TeV. The J/psi mesons are reconstructed in the e(+)e(-) decay channel and the measurements are performed at midrapidity (vertical bar y vertical bar &lt; 0.9) in the transverse-momentum interval 0 &lt; p(T) &lt; 40 GeV/c, using a minimum-bias data sample corresponding to an integrated luminosity L-int = 32.2 nb(-1) and an Electromagnetic Calorimeter triggered data sample with L-int = 8.3 pb(-1). The p(T)-integrated J/psi production cross section at midrapidity, computed using the minimumbias data sample, is d sigma/dy vertical bar(y) =0 = 8.97 +/- 0.24 (stat) 0.48 (syst) +/- 0.15 (lumi) mu b. An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and p(T)-differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models

Anisotropic flow of identified hadrons in Xe-Xe collisions at root s(NN)=5.44 TeV

Measurements of elliptic (v(2)) and triangular (v(3)) flow coefficients of pi(+/-), K-+/-, p+(p) over bar, K-S(0), and Lambda+(Lambda) over bar obtained with the scalar product method in Xe-Xe collisions at root sNN = 5.44TeV are presented. The results are obtained in the rapidity range |y| &lt; 0.5 and reported as a function of transverse momentum, p(T), for several collision centrality classes. The flow coefficients exhibit a particle mass dependence for pT &lt; 3 GeV/c, while a grouping according to particle type (i.e., meson and baryon) is found at intermediate transverse momenta (3 &lt; p(T) &lt; 8 GeV/c). The magnitude of the baryon v(2) is larger than that of mesons up to pT = 6 GeV/c. The centrality dependence of the shape evolution of the p(T)-differential v(2) is studied for the various hadron species. The v(2) coefficients of pi(+/-), K-+/-, and p+(p) over bar are reproduced by MUSIC hydrodynamic calculations coupled to a hadronic cascade model (UrQMD) for p(T) &lt; 1 GeV/c. A comparison with vn measurements in the corresponding centrality intervals in Pb-Pb collisions at root sNN = 5.02TeV yields an enhanced v(2) in central collisions and diminished value in semicentral collisions