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Background: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton-proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton-nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclear-matter effects. Most of these effects are expected to modify open-charm production at low transverse momenta (p(T)) and, so far, no measurement of D-meson production down to zero transverse momentum was available at mid-rapidity at the energies attained at the CERN Large Hadron Collider (LHC). Purpose: The measurements of the production cross sections of promptly produced charmed mesons in p-Pb collisions at the LHC down to p(T) = 0 and the comparison to the results from pp interactions are aimed at the assessment of cold-nuclear-matter effects on open-charm production, which is crucial for the interpretation of the results from Pb-Pb collisions. The prompt charmed mesons D-0, D+, D*+, and D-s(+) were measured at mid-rapidity in p-Pb collisions at a center-of-mass energy per nucleon pair root S-NN = 5.02 TeV with the ALICE detector at the LHC. D mesons were reconstructed from their decays D-0 -> K- pi(+), D+ -> K- pi(+) pi(+), D*+ -> D-0 pi(+), D-S(+) -> phi pi(+) -> K- K+ pi(+), and their charge conjugates, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. In addition, the prompt D 0 production cross section was measured in pp collisions at root S = 7 TeV and p-Pb collisions at root S-NN = 5.02 TeV down to p(T) = 0 using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the D-0 decay vertex. Results: The production cross section in pp collisions is described within uncertainties by different implementations of pQCD calculations down to p(T) = 0. This allowed also a determination of the total c (c) over bar production cross section in pp collisions, which is more precise than previous ALICE measurements because it is not affected by uncertainties owing to the extrapolation to pT = 0. The nuclear modification factor R-pPb( p(T)), defined as the ratio of the p(T)-differential D meson cross section in p-Pb collisions and that in pp collisions scaled by the mass number of the Pb nucleus, was calculated for the four D-meson species and found to be compatible with unity within uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium. Conclusions: These measurements add experimental evidence that the modification of the D-meson transverse momentum distributions observed in Pb-Pb collisions with respect to pp interactions is due to strong final-state effects induced by the interactions of the charm quarks with the hot and dense partonic medium created in ultrarelativistic heavy-ion collisions. The current precision of the measurement does not allow us to draw conclusions on the role of the different cold-nuclear-matter effects and on the possible presence of additional hot-medium effects in p-Pb collisions. However, the analysis technique without decay-vertex reconstruction, applied on future larger data samples, should provide access to the physics-rich range down to p(T) = 0.
D-meson production in p-Pb collisions at root S-NN=5.02 TeV and in pp collisions at root S=7 TeV
Adam, J.;Adamova, D.;Aggarwal, M. M.;Rinella, G. Aglieri;Agnello, M.;Agrawal, N.;Ahammed, Z.;Ahmad, S.;Ahn, S. U.;Aiola, S.;Akindinov, A.;Alam, S. N.;Albuquerque, D. S. D.;Aleksandrov, D.;Alessandro, B.;Alexandre, D.;Molina, R. Alfaro;Alici, A.;Alkin, A.;Alme, J.;Alt, T.;Altinpinar, S.;Altsybeev, I.;Prado, C. Alves Garcia;Andrei, C.;Andronic, A.;Anguelov, V.;Anticic, T.;Antinori, F.;Antonioli, P.;Aphecetche, L.;Appelshaeuser, H.;Arcelli, S.;Arnaldi, R.;Arnold, O. W.;Arsene, I. C.;Arslandok, M.;Audurier, B.;Augustinus, A.;Averbeck, R.;Azmi, M. D.;Badala, A.;Baek, Y. W.;Bagnasco, S.;Bailhache, R.;Bala, R.;Balasubramanian, S.;Baldisseri, A.;Baral, R. C.;Barbano, A. M.;Barbera, R.;Barile, F.;Barnafoldi, G. G.;Barnby, L. S.;Barret, V.;Bartalini, P.;Barth, K.;Bartke, J.;Bartsch, E.;Basile, M.;Bastid, N.;Basu, S.;Bathen, B.;Batigne, G.;Camejo, A. Batista;Batyunya, B.;Batzing, P. C.;Bearden, I. G.;Beck, H.;Bedda, C.;Behera, N. K.;Belikov, I.;Bellini, F.;Bello Martinez, H.;Bellwied, R.;Belmont, R.;Belmont Moreno, E.;Beltran, L. G. E.;Belyaev, V.;Bencedi, G.;Beole, S.;Berceanu, I.;Bercuci, A.;Berdnikov, Y.;Berenyi, D.;Bertens, R. A.;Berzano, D.;Betev, L.;Bhasin, A.;Bhat, I. R.;Bhati, A. K.;Bhattacharjee, B.;Bhom, J.;Bianchi, L.;Bianchi, N.;Bianchin, C.;Bielcik, J.;Bielcikova, J.;Bilandzic, A.;Biro, G.;Biswas, R.;Biswas, S.;Bjelogrlic, S.;Blair, J. T.;Blau, D.;Blume, C.;Bock, F.;Bogdanov, A.;Boggild, H.;Boldizsar, L.;Bombara, M.;Bonora, M.;Book, J.;Borel, H.;Borissov, A.;Borri, M.;Bossu, F.;Botta, E.;Bourjau, C.;Braun Munzinger, P.;Bregant, M.;Breitner, T.;Broker, T. A.;Browning, T. A.;Broz, M.;Brucken, E. J.;Bruna, E.;Bruno, G. E.;Budnikov, D.;Buesching, H.;Bufalino, S.;Buncic, P.;Busch, O.;Buthelezi, Z.;Butt, J. B.;Buxton, J. T.;Cabala, J.;Caffarri, D.;Cai, X.;Caines, H.;Diaz, L. Calero;Caliva, A.;Calvo Villar, E.;Camerini, P.;Carena, F.;Carena, W.;Carnesecchi, F.;Castellanos, J. Castillo;Castro, A. J.;CASULA, ESTER ANNA RITA;Ceballos Sanchez, C.;Cepila, J.;Cerello, P.;Cerkala, J.;Chang, B.;Chapeland, S.;Chartier, M.;Charvet, J. L.;Chattopadhyay, S.;Chattopadhyay, S.;Chauvin, A.;Chelnokov, V.;Cherney, M.;Cheshkov, C.;Cheynis, B.;Barroso, V. Chibante;Chinellato, D. D.;Cho, S.;Chochula, P.;Choi, K.;Chojnacki, M.;Choudhury, S.;Christakoglou, P.;Christensen, C. H.;Christiansen, P.;Chujo, T.;Chung, S. U.;CICALO', CORRADO;Cifarelli, L.;Cindolo, F.;Cleymans, J.;Colamaria, F.;Colella, D.;Collu, A.;Colocci, M.;Balbastre, G. Conesa;del Valle, Z. Conesa;Connors, M. E.;Contreras, J. G.;Cormier, T. M.;Morales, Y. Corrales;Cortes Maldonado, I.;Cortese, P.;Cosentino, M. R.;Costa, F.;Crkovska, J.;Crochet, P.;Albino, R. Cruz;Cuautle, E.;Cunqueiro, L.;Dahms, T.;Dainese, A.;Danisch, M. C.;Danu, A.;Das, D.;Das, I.;Das, S.;Dash, A.;Dash, S.;De, S.;De Caro, A.;de Cataldo, G.;de Conti, C.;de Cuveland, J.;DE FALCO, ALESSANDRO;De Gruttola, D.;De Marco, N.;De Pasquale, S.;De Souza, R. 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F.;Hillemanns, H.;Hippolyte, B.;Horak, D.;Hosokawa, R.;Hristov, P.;Hughes, C.;Humanic, T. J.;Hussain, N.;Hussain, T.;Hutter, D.;Hwang, D. S.;Ilkaev, R.;Inaba, M.;INCANI, ELISA;Ippolitov, M.;Irfan, M.;Isakov, V.;Ivanov, M.;Ivanov, V.;Izucheev, V.;Jacak, B.;Jacazio, N.;Jacobs, P. M.;Jadhav, M. B.;Jadlovska, S.;Jadlovsky, J.;Jahnke, C.;Jakubowska, M. J.;Janik, M. A.;Jayarathna, P. H. S. Y.;Jena, C.;Jena, S.;Bustamante, R. T. Jimenez;Jones, P. G.;Jusko, A.;Kalinak, P.;Kalweit, A.;Kang, J. H.;Kaplin, V.;Kar, S.;Uysal, A. Karasu;Karavichev, O.;Karavicheva, T.;Karayan, L.;Karpechev, E.;Kebschull, U.;Keidel, R.;Keijdener, D. L. D.;Keil, M.;Khan, M. Mohisin;Khan, P.;Khan, S. A.;Khanzadeev, A.;Kharlov, Y.;Khatun, A.;Kileng, B.;Kim, D. W.;Kim, D. J.;Kim, D.;Kim, H.;Kim, J. S.;Kim, J.;Kim, M.;Kim, S.;Kim, T.;Kirsch, S.;Kisel, I.;Kiselev, S.;Kisiel, A.;Kiss, G.;Klay, J. L.;Klein, C.;Klein, J.;Klein Boesing, C.;Klewin, S.;Kluge, A.;Knichel, M. L.;Knospe, A. 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I.;Loginov, V.;Loizides, C.;Lopez, X.;Lopez Torres, E.;Lowe, A.;Luettig, P.;Lunardon, M.;Luparello, G.;Lupi, M.;Lutz, T. H.;Maevskaya, A.;Mager, M.;Mahajan, S.;Mahmood, S. M.;Maire, A.;Majka, R. D.;Malaev, M.;Maldonado Cervantes, I.;Malinina, L.;Mal'Kevich, D.;Malzacher, P.;Mamonov, A.;Manko, V.;Manso, F.;Manzari, V.;Mao, Y.;Marchisone, M.;Mares, J.;Margagliotti, G. V.;Margotti, A.;Margutti, J.;Marin, A.;Markert, C.;Marquard, M.;Martin, N. A.;Martinengo, P.;Martinez, M. I.;Garcia, G. Martinez;Pedreira, M. Martinez;Mas, A.;Masciocchi, S.;Masera, M.;Masoni, A.;Mastroserio, A.;Matyja, A.;Mayer, C.;Mazer, J.;Mazzoni, M. A.;Mcdonald, D.;Meddi, F.;Melikyan, Y.;Menchaca Rocha, A.;Meninno, E.;Perez, J. Mercado;Meres, M.;Mhlanga, S.;Miake, Y.;Mieskolainen, M. M.;Mikhaylov, K.;Milano, L.;Milosevic, J.;Mischke, A.;Mishra, A. N.;Miskowiec, D.;Mitra, J.;Mitu, C. M.;Mohammadi, N.;Mohanty, B.;Mohler, C.;Molnar, L.;Montano Zetina, L.;Montes, E.;De Godoy, D. A. Moreira;Moreno, L. A. P.;Moretto, S.;Morreale, A.;Morsch, A.;Muccifora, V.;Mudnic, E.;Muehlheim, D.;Muhuri, S.;Mukherjee, M.;Mulligan, J. D.;Munhoz, M. G.;Muenning, K.;Munzer, R. H.;Murakami, H.;Murray, S.;Musa, L.;Musinsky, J.;Naik, B.;Nair, R.;Nandi, B. K.;Nania, R.;Nappi, E.;Naru, M. U.;da Luz, H. Natal;Nattrass, C.;Navarro, S. R.;Nayak, K.;Nayak, R.;Nayak, T. K.;Nazarenko, S.;Nedosekin, A.;De Oliveira, R. A. Negrao;Nellen, L.;Ng, F.;Nicassio, M.;Niculescu, M.;Niedziela, J.;Nielsen, B. S.;Nikolaev, S.;Nikulin, S.;Nikulin, V.;Noferini, F.;Nomokonov, P.;Nooren, G.;Noris, J. C. C.;Norman, J.;Nyanin, A.;Nystrand, J.;Oeschler, H.;Oh, S.;Oh, S. K.;Ohlson, A.;Okatan, A.;Okubo, T.;Oleniacz, J.;Da Silva, A. C. Oliveira;Oliver, M. H.;Onderwaater, J.;Oppedisano, C.;Orava, R.;Oravec, M.;Ortiz Velasquez, A.;Oskarsson, A.;Otwinowski, J.;Oyama, K.;Ozdemir, M.;Pachmayer, Y.;Pagano, D.;Pagano, P.;Paic, G.;Pal, S. K.;Palni, P.;Pan, J.;Pandey, A. K.;Papikyan, V.;Pappalardo, G. S.;Pareek, P.;Park, W. J.;Parmar, S.;Passfeld, A.;Paticchio, V.;Patra, R. N.;Paul, B.;Pei, H.;Peitzmann, T.;Peng, X.;Da Costa, H. Pereira;Peresunko, D.;Lezama, E. Perez;Peskov, V.;Pestov, Y.;Petracek, V.;Petrov, V.;Petrovici, M.;Petta, C.;Piano, S.;Pikna, M.;Pillot, P.;Pimentel, L. O. D. L.;Pinazza, O.;Pinsky, L.;Piyarathna, D. B.;Ploskon, M.;Planinic, M.;Pluta, J.;Pochybova, S.;Podesta Lerma, P. L. M.;Poghosyan, M. G.;Polichtchouk, B.;Poljak, N.;Poonsawat, W.;Pop, A.;Poppenborg, H.;Porteboeuf Houssais, S.;Porter, J.;Pospisil, J.;Prasad, S. K.;Preghenella, R.;Prino, F.;Pruneau, C. A.;Pshenichnov, I.;Puccio, M.;PUDDU, GIOVANNA;Pujahari, P.;Punin, V.;Putschke, J.;Qvigstad, H.;Rachevski, A.;Raha, S.;Rajput, S.;Rak, J.;Rakotozafindrabe, A.;Ramello, L.;Rami, F.;Raniwala, R.;Raniwala, S.;Rasanen, S. S.;Rascanu, B. T.;Rathee, D.;Ravasenga, I.;Read, K. F.;Redlich, K.;Reed, R. J.;Rehman, A.;Reichelt, P.;Reidt, F.;Ren, X.;Renfordt, R.;Reolon, A. R.;Reshetin, A.;Reygers, K.;Riabov, V.;Ricci, R. 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H.;Yurchenko, V.;Zaborowska, A.;Zaccolo, V.;Zaman, A.;Zampolli, C.;Zanoli, H. J. C.;Zaporozhets, S.;Zardoshti, N.;Zarochentsev, A.;Zavada, P.;Zaviyalov, N.;Zbroszczyk, H.;Zgura, I. S.;Zhalov, M.;Zhang, H.;Zhang, X.;Zhang, Y.;Zhang, C.;Zhang, Z.;Zhao, C.;Zhigareva, N.;Zhou, D.;Zhou, Y.;Zhou, Z.;Zhu, H.;Zhu, J.;Zichichi, A.;Zimmermann, A.;Zimmermann, M. B.;Zinovjev, G.;Zyzak, M.
2016-01-01
Abstract
Background: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton-proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton-nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclear-matter effects. Most of these effects are expected to modify open-charm production at low transverse momenta (p(T)) and, so far, no measurement of D-meson production down to zero transverse momentum was available at mid-rapidity at the energies attained at the CERN Large Hadron Collider (LHC). Purpose: The measurements of the production cross sections of promptly produced charmed mesons in p-Pb collisions at the LHC down to p(T) = 0 and the comparison to the results from pp interactions are aimed at the assessment of cold-nuclear-matter effects on open-charm production, which is crucial for the interpretation of the results from Pb-Pb collisions. The prompt charmed mesons D-0, D+, D*+, and D-s(+) were measured at mid-rapidity in p-Pb collisions at a center-of-mass energy per nucleon pair root S-NN = 5.02 TeV with the ALICE detector at the LHC. D mesons were reconstructed from their decays D-0 -> K- pi(+), D+ -> K- pi(+) pi(+), D*+ -> D-0 pi(+), D-S(+) -> phi pi(+) -> K- K+ pi(+), and their charge conjugates, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. In addition, the prompt D 0 production cross section was measured in pp collisions at root S = 7 TeV and p-Pb collisions at root S-NN = 5.02 TeV down to p(T) = 0 using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the D-0 decay vertex. Results: The production cross section in pp collisions is described within uncertainties by different implementations of pQCD calculations down to p(T) = 0. This allowed also a determination of the total c (c) over bar production cross section in pp collisions, which is more precise than previous ALICE measurements because it is not affected by uncertainties owing to the extrapolation to pT = 0. The nuclear modification factor R-pPb( p(T)), defined as the ratio of the p(T)-differential D meson cross section in p-Pb collisions and that in pp collisions scaled by the mass number of the Pb nucleus, was calculated for the four D-meson species and found to be compatible with unity within uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium. Conclusions: These measurements add experimental evidence that the modification of the D-meson transverse momentum distributions observed in Pb-Pb collisions with respect to pp interactions is due to strong final-state effects induced by the interactions of the charm quarks with the hot and dense partonic medium created in ultrarelativistic heavy-ion collisions. The current precision of the measurement does not allow us to draw conclusions on the role of the different cold-nuclear-matter effects and on the possible presence of additional hot-medium effects in p-Pb collisions. However, the analysis technique without decay-vertex reconstruction, applied on future larger data samples, should provide access to the physics-rich range down to p(T) = 0.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/216413
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