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5. Unconventional Mechanisms of Heavy Quark Fragmentation.

Author

Kopeliovich, Boris, Nemchik, Jan, Potashnikova, Irina, and Schmidt, Ivan

Subjects
*FLAVOR in particle physics, *QUARKS, *HEAVY ion collisions, *MESONS
Abstract

Heavy and light quarks produced in high- p T partonic collisions radiate differently. Heavy quarks regenerate their color field, stripped-off in the hard reaction, much faster than the light ones and radiate a significantly smaller fraction of the initial quark energy. This peculiar feature of heavy-quark jets leads to a specific shape of the fragmentation functions observed in e + e − annihilation. Differently from light flavors, the heavy quark fragmentation function strongly peaks at large fractional momentum z, i.e., the produced heavy–light mesons, B or D, carry the main fraction of the jet momentum. This is a clear evidence of the dead-cone effect, and of a short production time of a heavy–light mesons. Contrary to propagation of a small q q ¯ dipole, which survives in the medium due to color transparency, a heavy–light Q q ¯ dipole promptly expands to a large size. Such a big dipole has no chance to remain intact in a dense medium produced in relativistic heavy ion collisions. On the other hand, a breakup of such a dipole does not affect much the production rate of Q q ¯ mesons, differently from the case of light q q ¯ meson production. [ABSTRACT FROM AUTHOR]

Published
2023
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8. New opportunities at the photon energy frontier

Author

Klein, Spencer, Tapia Takaki, Daniel, Adam, Jaroslav, Aidala, Christine, Angerami, Aaron, Audurier, Benjamin, Bertulani, Carlos, Bierlich, Christian, Blok, Boris, Brandenburg, James Daniel, Brodsky, Stanley, Bylinkin, Aleksandr, Canoa Roman, Veronica, Francesco Giovanni Celiberto, Cepila, Jan, Chachamis, Grigorios, Cole, Brian, Contreras, Guillermo, D Enterria, David, Dumitru, Adrian, Fernández Téllez, Arturo, Frankfurt, Leonid, Gay Ducati, Maria Beatriz, Geurts, Frank, Da Silveira, Gustavo Gil, Giuli, Francesco, Goncalves, Victor P., Grabowska-Bold, Iwona, Guzey, Vadim, Harland-Lang, Lucian, Hentschinski, Martin, Hobbs, T. J., Jalilian-Marian, Jamal, Khoze, Valery A., Kim, Yongsun, Klein, Spencer R., Knapen, Simon, Kłusek-Gawenda, Mariola, Krelina, Michal, Kryshen, Evgeny, Lappi, Tuomas, Loizides, Constantin, Luszczak, Agnieszka, Machado, Magno, Mäntysaari, Heikki, Martins, Daniel, Mcnulty, Ronan, Murray, Michael, Nemchik, Jan, Noronha-Hostler, Jacquelyn, Nystrand, Joakim, Papa, Alessandro, Pire, Bernard, Ploskon, Mateusz, Przybycien, Marius, Ralston, John P., Rebello Teles, Patricia, Royon, Christophe, Schenke, Björn, Schmidke, William, Seger, Janet, Stasto, Anna, Steinberg, Peter, Strikman, Mark, Szczurek, Antoni, Szymanowski, Lech, Ulrich, Ralf, Villalobos Baillie, Orlando, Vogt, Ramona, Wallon, Samuel, Winn, Michael, Xie, Keping, Xu, Zhangbu, Yang, Shuai, Zhalov, Mikhail, Zhou, Jian, Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Physique Théorique [Palaiseau] (CPHT), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), National Center for Nuclear Research [Warsaw] (NCBJ), National Center for Nuclear Research (NCBJ), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Pire, Bernard

Subjects
[PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], hep-ex, Nuclear Theory, High Energy Physics::Phenomenology, FOS: Physical sciences, hep-ph, nucl-ex, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Physics - Experiment, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment, Particle Physics - Experiment, Particle Physics - Phenomenology
Abstract

Ultra-peripheral collisions (UPCs) involving heavy ions and protons are the energy frontier for photon-mediated interactions. UPC photons can be used for many purposes, including probing low-$x$ gluons via photoproduction of dijets and vector mesons, probes of beyond-standard-model processes, such as those enabled by light-by-light scattering, and studies of two-photon production of the Higgs., Letter of Interest submitted to Snowmass 2021

Published
2020

10. Survival of heavy flavored mesons in a hot medium

Author

Kopeliovich, B. Z., Nemchik, Jan, Potashnikova, I. K., and Schmidt, Ivan

Subjects
Nuclear Theory (nucl-th), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Nuclear Theory, High Energy Physics::Phenomenology, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract

Hadronization of heavy quarks reveals various unusual features. Gluon radiation by a heavy quark originated from a hard process, ceases shortly on a distance of the order of few fm. Due to the dead-cone effect a heavy quark radiates only a small fraction of its energy. This is why the measured fragmentation function D(z) peaks at large z. Hadronization finishes at very short distances, well shorter than 1 fm, by production of a colorless small-size Qq-bar dipole. This ensures dominance of a perturbative mechanism and makes possible factorization of short and long distances. The latter corresponds to final state interactions of the produced dipole propagating through a dense medium. The results provide good description of data on beauty and charm suppression in heavy ion collisions, fixing the transport coefficient for b-quarks about twice smaller than for charm, and both significantly lower that the values determined from data on suppression of high-pT light hadrons. We relate this to reduction of the QCD coupling at higher scales, and suppression of radiation by the dead-cone effect., 9 pages, 6 figures

Published
2019

11. Cronin effect at different energies: from RHIC to LHC

Author

Krelina Michal and Nemchik Jan

Subjects
Physics, QC1-999
Abstract

Using the QCD improved parton model we study production of hadrons with large transverse momenta pT in proton-proton and proton-nucleus collisions at different energies corresponding to experiments at RHIC and LHC. For investigation of large-pT hadrons produced on nuclear targets we include additionally the nuclear modification of parton distribution functions and the nuclear broadening calculated within the color dipole formalism. We demonstrate that complementary effect of initial state interactions causes a significant suppression at large pT and at forward rapidities. We provide a good description of the Cronin effect at medium-high pT and the nuclear suppression at large pT in agreement with available data from experiments at RHIC and LHC. In the LHC energy range this large-pT suppression expected at forward rapidities can be verified by the future measurements.

Published
2014
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12. Production of hadrons in proton-nucleus collisions: from RHIC to LHC

Author

Krelina Michal and Nemchik Jan

Subjects
Physics, QC1-999
Abstract

We study nuclear effects in production of large−pT hadrons on nuclear targets at different energies corresponding to RHIC and LHC experiments. For calculations we employ the QCD improved parton model including the intrinsic parton transverse momenta and the nuclear broadening. Besides nuclear modification of parton distribution functions we include also the complementary effect of initial state interactions causing a significant nuclear suppression at large−pT and at forward rapidities violating so the QCD factorization. Numerical results for nucleus-to-nucleon ratios are compared with available data from experiments at RHIC and LHC. We perform also predictions for nuclear effects at LHC expected at forward rapidities.

Published
2013
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13. A heuristic description of high-pT hadron production in heavy ion collisions

Author

Nemchik, Jan, Pasechnik, Roman, and Potashnikova, Irina

Subjects
Nuclear Theory (nucl-th), High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment, High Energy Physics - Experiment
Abstract

Using a simplified model for in-medium dipole evolution accounting for color filtering effects we study production of hadrons at large transverse momenta $p_T$ in heavy ion collisions. In the framework of this model, several important sources of the nuclear suppression observed recently at RHIC and LHC have been analysed. A short production length of the leading hadron $l_p$ causes a strong onset of color transparency effects manifested themselves as a steep rise of the nuclear modification factor $R_{AA}(p_T)$ at large hadron $p_T$'s. A dominance of quarks with higher $l_p$ leads to a weaker suppression at RHIC than the one observed at LHC. In the RHIC kinematic region we include an additional suppression factor steeply falling with $p_T$, which is tightly related to the energy conservation constraints. The latter is irrelevant at LHC up to $p_T\lesssim 70$ GeV while it causes a rather flat $p_T$ dependence of the $R_{AA}(p_T)$ factor at RHIC c.m. energy $\sqrt{s} = 200$ GeV and even an increasing suppression with $p_T$ at $\sqrt{s} = 62$ GeV. The calculations contain only a medium density adjustment, and for an initial time scale $t_0$ = 1 fm we found the energy-dependent maximal values of the transport coefficient, $\hat{q}_0 = 0.7, 1.0$ and 1.3 GeV$^2$/fm corresponding to $\sqrt{s} = 62, 200$ GeV and 2.76 TeV, respectively. We present a broad variety of predictions for the nuclear modification factor and the azimuthal asymmetry which are in a good agreement with available data from experiments at RHIC and LHC., 14 pages, 17 figures; extra clarifications added in Sects. II and III (with additional Figs. 1-6) and in the extended Sect. V B (with additional Fig.11), references added, conclusions unchanged

Published
2014

14. Predictions for p plus pb collisions at root s(nn)=5 tev

Author

Albacete, Javier L., Armesto, Nestor, Baier, Rudolf, Barnafoeldi, Gergely G., Barrette, Jean, De, Somnath, Deng, Wei-Tian, Dumitru, Adrian, Dusling, Kevin, Eskola, Kari J., Fries, Rainer, Fujii, Hirotsugu, Gelis, Francois, Gyulassy, Miklos, He, Yuncun, Helenius, Ilkka, Kang, Zhong-Bo, Kopeliovich, Boris Z., Kutak, Krzysztof, Levai, Peter, Lin, Zi-Wei, Mueller, Alfred H., Nara, Yasushi, Nemchik, Jan, Papp, Gabor, Petrovici, Mihai, Qiu, Jian-Wei, Rezaeian, Amir H., Ru, Peng, Schiff, Dominique, Sapeta, Sebastian, Pop, Vasile Topor, Tribedy, Prithwish, Venugopalan, Raju, Vitev, Ivan, Vogt, Ramona, Wang, Enke, Wang, Xin-Nian, Xing, Hongxi, Xu, Rong, Zhang, Ben-Wei, and Zhang, Wei-Ning

Published
2013

15. Predictions for p+pb collisions at (raiz cuadrada de)8nn = 5 tev

Author

Albacete, Javier L., Armesto, Nestor, Baier, Rudolf, Barnafoeldi, Gergely G., Barrette, Jean, De, Somnath, Deng, Wei-Tian, Dumitru, Adrian, Dusling, Kevin, Eskola, Kari J., Fries, Rainer, Fujii, Hirotsugu, Gelis, Francois, Gyulassy, Miklos, He, Yuncun, Helenius, Ilkka, Kang, Zhong-Bo, Kopeliovich, Boris Z., Kutak, Krzysztof, Levai, Peter, Lin, Zi-Wei, Mueller, Alfred H., Nara, Yasushi, Nemchik, Jan, Papp, Gabor, Petrovici, Mihai, Qiu, Jian-Wei, Rezaeian, Amir H., Ru, Peng, Schiff, Dominique, Sapeta, Sebastian, Pop, Vasile Topor, Tribedy, Prithwish, Venugopalan, Raju, Vitev, Ivan, Vogt, Ramona, Wang, Enke, Wang, Xin-Nian, Xing, Hongxi, Xu, Rong, Zhang, Ben-Wei, and Zhang, Wei-Ning

Published
2013

16. Predictions for $p+Pb$ Collisions at $\sqrt s_NN = 5 TeV$

Author

Albacete, Javier L., Armesto, Nestor, Baier, Rudolf, Barnafoeldi, Gergely G., Barrette, Jean, De, Somnath, Deng, Wei-Tian, Dumitru, Adrian, Dusling, Kevin, Eskola, Kari J., Fries, Rainer, Fujii, Hirotsugu, Gelis, Francois, Gyulassy, Miklos, He, Yuncun, Helenius, Ilkka, Kang, Zhong-Bo, Kopeliovich, Boris Z., Kutak, Krzysztof, Levai, Peter, Lin, Zi-Wei, Mueller, Alfred H., Nara, Yasushi, Nemchik, Jan, Papp, Gabor, Petrovici, Mihai, Qiu, Jian-Wei, Rezaeian, Amir H., Ru, Peng, Schiff, Dominique, Sapeta, Sebastian, Pop, Vasile Topor, Tribedy, Prithwish, Venugopalan, Raju, Vitev, Ivan, Vogt, Ramona, Wang, Enke, Wang, Xin-Nian, Xing, Hongxi, Xu, Rong, Zhang, Ben-Wei, Zhang, Wei-Ning, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Fakultät für Physik, Universität Bielefeld, Laboratoire Aimé Cotton (LAC), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École normale supérieure - Cachan (ENS Cachan), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Théorique d'Orsay [Orsay] (LPT), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Théorique et Hautes Energies (LPTHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Frederick Seitz Materials Research Laboratory, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Cachan (ENS Cachan)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Theory (nucl-th), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Astrophysics::High Energy Astrophysical Phenomena, High Energy Physics::Phenomenology, Perturbative QCD, FOS: Physical sciences, High Energy Physics::Experiment, hard probes of heavy-ion collisions, Nuclear Experiment
Abstract

Predictions for charged hadron, identified light hadron, quarkonium, photon, jet and gauge bosons in p+Pb collisions at sqrt s_NN = 5 TeV are compiled and compared. When test run data are available, they are compared to the model predictions., 84 pages

Published
2013
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18. Heavy flavor production in high-energy pp collisions: Color dipole description.

Author

Goncalves, Victor P., Kopeliovich, Boris, Nemchik, Jan, Pasechnik, Roman, and Potashnikova, Irina

Subjects
*LARGE Hadron Collider, *MOMENTUM (Mechanics), *MESONS
Abstract

We present a detailed study of open heavy flavor production in high-energy p p collisions at the LHC in the color dipole framework. The transverse momentum distributions of produced b -jets, accounting for the jet energy loss, as well as produced open charm D and bottom B mesons in distinct rapidity intervals relevant for LHC measurements are computed. The dipole model results for the differential b -jet production cross section are compared to the recent ATLAS and CMS data while the results for D and B mesons production cross sections--to the corresponding LHCb data. Several models for the phenomenological dipole cross section have been employed to estimate theoretical uncertainties of the dipole model predictions. We demonstrate that the primordial transverse momentum distribution of the projectile gluon significantly affects the meson spectra at low transverse momenta and contributes to the largest uncertainty of the dipole model predictions. [ABSTRACT FROM AUTHOR]

Published
2017
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19. Drell-Yan process in pA collisions: Path-integral treatment of coherence effects.

Author

Goncalves, Victor P., Krelina, Michal, Nemchik, Jan, and Pasechnik, Roman

Subjects
*COLLISIONS (Nuclear physics), *QUANTUM coherence, *PATH integrals
Abstract

In this work, we investigate production of Drell-Yan (DY) pairs in proton-nucleus collisions in kinematic regions where the corresponding coherence length does not exceed the nuclear radius, RA, and the quantum coherence effects should be treated with special care. The results for the nucleus-to-nucleon production ratio available in the literature so far are usually based on the assumption of a very long coherence length (LCL) lc ≫ RA. Since the onset of coherence effects is controlled by the coherence length lc, we estimated its magnitude in various kinematic regions of the DY process and found that the LCL approximation should not be used at small and medium c.m. collision energies (√s ≲ 200 GeV) as well as at large dilepton invariant masses. In order to obtain realistic predictions, we computed for the first time the DY cross section using the generalized color dipole approach based on the rigorous Green function formalism, which naturally incorporates the color transparency and quantum coherence effects and hence allows us to estimate the nuclear shadowing with no restrictions on the CL. In addition to the shadowing effect, we studied a complementary effect of initial state interactions (ISI) that causes an additional suppression at large values of the Feynman variable. Numerical results for the nuclear modification factor accounting for the ISI effect and the finite lc are compared to the data available from the fixed-target Fermi National Laboratory measurements and a good agreement has been found. Besides, we present new predictions for the nuclear suppression as a function of dilepton rapidity and invariant mass in the kinematic regions that can be probed by the RHIC collider as well as by the planned AFTER@LHC and LHCb fixed-target experiments. [ABSTRACT FROM AUTHOR]

Published
2016
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