Multiplicity dependence of (anti-)deuteron production in pp collisions at root s=7 TeV

none1019siIn this letter, the production of deuterons and anti-deuterons in pp collisions at root s = 7 TeV is studied as a function of the charged-particle multiplicity density at mid-rapidity with the ALICE detector at the LHC. Production yields are measured at mid-rapidity in five multiplicity classes and as a function of the deuteron transverse momentum (p(T)). The measurements are discussed in the context of hadron-coalescence models. The coalescence parameter B-2, extracted from the measured spectra of (anti-)deuteronsand primary (anti-)protons, exhibits no significant p(T)-dependence for p(T) < 3 GeV/c, in agreement with the expectations of a simple coalescence picture. At fixed transverse momentum per nucleon, the B-2 parameter is found to decrease smoothly from low multiplicity pp to Pb-Pb collisions, in qualitative agreement with more elaborate coalescence models. The measured mean transverse momentum of (anti-)deuterons in pp is not reproduced by the Blast-Wave model calculations that simultaneously describe pion, kaon and proton spectra, in contrast to central Pb-Pb collisions. The ratio between the p(T)-integrated yield of deuterons to protons, d/p, is found to increase with the charged-particle multiplicity, as observed in inelastic pp collisions at different centre-of-mass energies. The d/p ratios are reported in a wide range, from the lowest to the highest multiplicity values measured in pp collisions at the LHC. (C) 2019 The Author(s). Published by Elsevier B.VnoneAcharya, S.; Acosta, F. T.; Adamova, D.; Adhya, S. P.; Adler, A.; Adolfsson, J.; Aggarwal, M. M.; Rinella, G. Aglieri; Agnello, M.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Al-Turany, M.; Alam, S. N.; Albuquerque, D. S. D.; Aleksandrov, D.; Alessandro, B.; Alfanda, H. M.; Alfaro Molina, R.; Ali, B.; Ali, Y.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altenkamper, L.; Altsybeev, I; Anaam, M. N.; Andrei, C.; Andreou, D.; Andrews, H. A.; Andronic, A.; Angeletti, M.; Anguelov, V; Anson, C.; Anticic, T.; Antinori, F.; Antonioli, P.; Anwar, R.; Apadula, N.; Aphecetche, L.; Appelshaeuser, H.; Arcelli, S.; Arnaldi, R.; Arratia, M.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badala, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Baral, R. C.; Barbera, R.; Barioglio, L.; Barnafoldi, G. G.; Barnby, L. S.; Barret, V; Bartalini, P.; Barth, K.; Bartsch, E.; Bastid, N.; Basu, S.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Bauri, D.; Bazo Alba, J. L.; Bearden, I. G.; Bedda, C.; Behera, N. K.; Belikov, I; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Beltran, L. G. E.; Belyaev, V; Bencedi, G.; Beole, S.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhatt, H.; Bhattacharjee, B.; Bianchi, A.; Bianchi, L.; Bianchi, N.; Bielcik, J.; Bielcikova, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Blair, J. T.; Blau, D.; Blume, C.; Boca, G.; Bock, F.; Bogdanov, A.; Boldizsar, L.; Bolozdynya, A.; Bombara, M.; Bonomi, G.; Bonora, M.; Borel, H.; Borissov, A.; Borri, M.; Botta, E.; Bourjau, C.; Bratrud, L.; Braun-Munzinger, P.; Bregant, M.; Broker, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Buckland, M. D.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buhler, P.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camacho, R. S.; Camerini, P.; Capon, A. A.; Carnesecchi, F.; Castellanos, J. Castillo; Castro, A. J.; Casula, E. A. R.; Sanchez, C. Ceballos; Chakraborty, P.; Chandra, S.; Chang, B.; Chang, W.; Chapeland, S.; Chartier, M.; Chattopadhyay, S.; Chauvin, A.; Cheshkov, C.; Cheynis, B.; Barroso, V. Chibante; Chinellato, D. D.; Cho, S.; Chochula, P.; Chowdhury, T.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Concas, M.; Balbastre, G. Conesa; del Valle, Z. Conesa; Contin, G.; Contreras, J. G.; Cormier, T. M.; Morales, Y. Corrales; Cortese, P.; Cosentino, M. R.; Costa, F.; Costanza, S.; Crkovska, J.; Crochet, P.; Cuautle, E.; Cunqueiro, L.; Dabrowski, D.; Dahms, T.; Dainese, A.; Damas, F. P. A.; Dani, S.; Danisch, M. C.; Danu, A.; Das, D.; Das, I; Das, S.; Dash, A.; Dash, S.; Dashi, A.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; De Souza, R. D.; Degenhardt, H. F.; Deisting, A.; Deloff, A.; Delsanto, S.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Diaz, R. A.; Dietel, T.; Dillenseger, P.; Ding, Y.; Divia, R.; Djuvsland, O.; Dobrin, A.; Domenicis Gimenez, D.; Doenigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Dudi, S.; Duggal, A. K.; Dukhishyam, M.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Epple, E.; Erazmus, B.; Erhardt, F.; Erokhin, A.; Ersdal, M. R.; Espagnon, B.; Eulisse, G.; Eum, J.; Evans, D.; Evdokimov, S.; Fabbietti, L.; Faggin, M.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Fernandez Tellez, A.; Ferrero, A.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiorenza, G.; Flor, F.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Girard, M. Fusco; Gaardhoje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Galvan, C. D.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Garg, K.; Gargiulo, C.; Garner, K.; Gasik, P.; Gauger, E. 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C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badala, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Baral, R. C.; Barbera, R.; Barioglio, L.; Barnafoldi, G. G.; Barnby, L. S.; Barret, V; Bartalini, P.; Barth, K.; Bartsch, E.; Bastid, N.; Basu, S.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Bauri, D.; Bazo Alba, J. L.; Bearden, I. G.; Bedda, C.; Behera, N. K.; Belikov, I; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Beltran, L. G. E.; Belyaev, V; Bencedi, G.; Beole, S.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhatt, H.; Bhattacharjee, B.; Bianchi, A.; Bianchi, L.; Bianchi, N.; Bielcik, J.; Bielcikova, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Blair, J. T.; Blau, D.; Blume, C.; Boca, G.; Bock, F.; Bogdanov, A.; Boldizsar, L.; Bolozdynya, A.; Bombara, M.; Bonomi, G.; Bonora, M.; Borel, H.; Borissov, A.; Borri, M.; Botta, E.; Bourjau, C.; Bratrud, L.; Braun-Munzinger, P.; Bregant, M.; Broker, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Buckland, M. D.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buhler, P.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camacho, R. S.; Camerini, P.; Capon, A. A.; Carnesecchi, F.; Castellanos, J. Castillo; Castro, A. J.; Casula, E. A. R.; Sanchez, C. Ceballos; Chakraborty, P.; Chandra, S.; Chang, B.; Chang, W.; Chapeland, S.; Chartier, M.; Chattopadhyay, S.; Chauvin, A.; Cheshkov, C.; Cheynis, B.; Barroso, V. Chibante; Chinellato, D. D.; Cho, S.; Chochula, P.; Chowdhury, T.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Concas, M.; Balbastre, G. Conesa; del Valle, Z. Conesa; Contin, G.; Contreras, J. G.; Cormier, T. M.; Morales, Y. Corrales; Cortese, P.; Cosentino, M. R.; Costa, F.; Costanza, S.; Crkovska, J.; Crochet, P.; Cuautle, E.; Cunqueiro, L.; Dabrowski, D.; Dahms, T.; Dainese, A.; Damas, F. P. A.; Dani, S.; Danisch, M. C.; Danu, A.; Das, D.; Das, I; Das, S.; Dash, A.; Dash, S.; Dashi, A.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; De Souza, R. D.; Degenhardt, H. F.; Deisting, A.; Deloff, A.; Delsanto, S.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Diaz, R. A.; Dietel, T.; Dillenseger, P.; Ding, Y.; Divia, R.; Djuvsland, O.; Dobrin, A.; Domenicis Gimenez, D.; Doenigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Dudi, S.; Duggal, A. K.; Dukhishyam, M.; Dupieux, P.; Ehlers, R. 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K.; Kollegger, T.; Kondratyeva, N.; Kondratyuk, E.; Konopka, P. J.; Konyushikhin, M.; Koska, L.; Kovalenko, O.; Kovalenko, V; Kowalski, M.; Kralik, I; Krav

Multiplicity dependence of light (anti-)nuclei production in p–Pb collisions at sNN=5.02 TeV

The measurement of the deuteron and anti-deuteron production in the rapidity range −1 < y < 0 as a function of transverse momentum and event multiplicity in p–Pb collisions at √sNN = 5.02 TeV is presented. (Anti-)deuterons are identified via their specific energy loss dE/dx and via their time-of- flight. Their production in p–Pb collisions is compared to pp and Pb–Pb collisions and is discussed within the context of thermal and coalescence models. The ratio of integrated yields of deuterons to protons (d/p) shows a significant increase as a function of the charged-particle multiplicity of the event starting from values similar to those observed in pp collisions at low multiplicities and approaching those observed in Pb–Pb collisions at high multiplicities. The mean transverse particle momenta are extracted from the deuteron spectra and the values are similar to those obtained for p and particles. Thus, deuteron spectra do not follow mass ordering. This behaviour is in contrast to the trend observed for non-composite particles in p–Pb collisions. In addition, the production of the rare 3He and 3He nuclei has been studied. The spectrum corresponding to all non-single diffractive p-Pb collisions is obtained in the rapidity window −1 < y < 0 and the pT-integrated yield dN/dy is extracted. It is found that the yields of protons, deuterons, and 3He, normalised by the spin degeneracy factor, follow an exponential decrease with mass number

Multiplicity dependence of (anti-)deuteron production in pp collisions at 1as=7TeV

In this letter, the production of deuterons and anti-deuterons in pp collisions at 1as = 7 TeV is studied as a function of the charged-particle multiplicity density at mid-rapidity with the ALICE detector at the LHC. Production yields are measured at mid-rapidity in five multiplicity classes and as a function of the deuteron transverse momentum (pT). The measurements are discussed in the context of hadron\u2013coalescence models. The coalescence parameter B2, extracted from the measured spectra of (anti-)deuterons and primary (anti-)protons, exhibits no significant pT-dependence for pT < 3 GeV/c, in agreement with the expectations of a simple coalescence picture. At fixed transverse momentum per nucleon, the B2 parameter is found to decrease smoothly from low multiplicity pp to Pb\u2013Pb collisions, in qualitative agreement with more elaborate coalescence models. The measured mean transverse momentum of (anti-)deuterons in pp is not reproduced by the Blast-Wave model calculations that simultaneously describe pion, kaon and proton spectra, in contrast to central Pb\u2013Pb collisions. The ratio between the pT-integrated yield of deuterons to protons, d/p, is found to increase with the charged- particle multiplicity, as observed in inelastic pp collisions at different centre-of-mass energies. The d/p ratios are reported in a wide range, from the lowest to the highest multiplicity values measured in pp collisions at the LHC

Multiplicity dependence of (anti-)deuteron production in pp collisions at s\sqrt{s} = 7 TeV

In this letter, the production of deuterons and anti-deuterons in pp collisions at $\sqrt{s}$ = 7 TeV is studied as a function of the charged-particle multiplicity density at mid-rapidity with the ALICE detector at the LHC. Production yields are measured at mid-rapidity in five multiplicity classes and as a function of the deuteron transverse momentum ($p_{\rm T}$). The measurements are discussed in the context of hadron–coalescence models. The coalescence parameter B$_2$ , extracted from the measured spectra of (anti-)deuterons and primary (anti-)protons, exhibits no significant $p_{\rm T}$-dependence for $p_{\rm T}$ < 3 GeV/c , in agreement with the expectations of a simple coalescence picture. At fixed transverse momentum per nucleon, the B$_2$ parameter is found to decrease smoothly from low multiplicity pp to Pb–Pb collisions, in qualitative agreement with more elaborate coalescence models. The measured mean transverse momentum of (anti-)deuterons in pp is not reproduced by the Blast-Wave model calculations that simultaneously describe pion, kaon and proton spectra, in contrast to central Pb–Pb collisions. The ratio between the $p_{\rm T}$-integrated yield of deuterons to protons, d/p, is found to increase with the charged-particle multiplicity, as observed in inelastic pp collisions at different centre-of-mass energies. The d/p ratios are reported in a wide range, from the lowest to the highest multiplicity values measured in pp collisions at the LHC

Coherent J/ψ\psi photoproduction at forward rapidity in ultra-peripheral Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm{NN}}}=5.02 TeV

The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The J/ψ is detected via its dimuon decay in the forward rapidity region (−4.0 < y <−2.5 ) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 $\mu$b$^{-1}$ . The cross section for coherent J/ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J/ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons

Measurement of charged jet cross section in pppp collisions at s=5.02{\sqrt{s}=5.02} TeV

International audienceThe cross section of jets reconstructed from charged particles is measured in the transverse momentum range of 5<pT<100  GeV/c in pp collisions at the center-of-mass energy of s=5.02  TeV with the ALICE detector. The jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, and 0.6 in the pseudorapidity range |η|<0.9-R. The charged jet cross sections are compared with the leading-order (LO) and to next-to-leading-order (NLO) perturbative quantum chromodynamics (pQCD) calculations. It is found that the NLO calculations agree better with the measurements. The cross section ratios for different resolution parameters are also measured. These ratios increase from low pT to high pT and saturate at high pT, indicating that jet collimation is larger at high pT than at low pT. These results provide a precision test of pQCD predictions and serve as a baseline for the measurement in Pb-Pb collisions at the same energy to quantify the effects of the hot and dense medium created in heavy-ion collisions at the LHC

Real-time data processing in the ALICE High Level Trigger at the LHC

International audienceAt the Large Hadron Collider at CERN in Geneva, Switzerland, atomic nuclei are collided at ultra-relativistic energies. Many final-state particles are produced in each collision and their properties are measured by the ALICE detector. The detector signals induced by the produced particles are digitized leading to data rates that are in excess of 48 GB/s. The ALICE High Level Trigger (HLT) system pioneered the use of FPGA- and GPU-based algorithms to reconstruct charged-particle trajectories and reduce the data size in real time. The results of the reconstruction of the collision events, available online, are used for high level data quality and detector-performance monitoring and real-time time-dependent detector calibration. The online data compression techniques developed and used in the ALICE HLT have more than quadrupled the amount of data that can be stored for offline event processing

Measurement of charged jet cross section in pp collisions at √s = 5.02 TeV

The cross section of jets reconstructed from charged particles is measured in the transverse momentum range of 5<pT<100 GeV/c in pp collisions at the center-of-mass energy of s√=5.02 TeV with the ALICE detector. The jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, and 0.6 in the pseudorapidity range |η|<0.9−R. The charged jet cross sections are compared with the leading order (LO) and to next-to-leading order (NLO) perturbative Quantum ChromoDynamics (pQCD) calculations. It was found that the NLO calculations agree better with the measurements. The cross section ratios for different resolution parameters were also measured. These ratios increase from low pT to high pT and saturate at high pT, indicating that jet collimation is larger at high pT than at low pT. These results provide a precision test of pQCD predictions and serve as a baseline for the measurement in Pb−Pb collisions at the same energy to quantify the effects of the hot and dense medium created in heavy-ion collisions at the LHC