## Nuclear and Quark Matter Seminar 2019 |

Dates:

07.02. |
05.03. |
05.06. |
14.08. |
18.09. |
16.10. |
04.12. |

Previous years: 2018 | 2017 | 2016 | 2015 | 2014 | 2013

- 7 February 2019, 16:30 - EMMI/KBW Lecture Hall Side room (1.17)

Evgeny Kryshen - Petersburg Nuclear Physics Institute

Shedding light on hadron structure with ultra-peripheral collisions

Abstract

Lead nuclei, accelerated at the LHC, are sources of strong electromagnetic fields that can be used to measure photon-induced interactions in a new kinematic regime. These interactions are usually studied in ultra-peripheral p-Pb and Pb-Pb collisions where hadronic interactions are strongly suppressed. Vector meson photoproduction is of particular interest since it is sensitive to gluon distributions in target hadrons. In this talk, an overview of ALICE, CMS and LHCb results on vector meson photoproduction in ultra-peripheral Pb-Pb and p-Pb collisions will be presented. Implications for the study of gluon saturation effects and nuclear gluon shadowing will be discussed. In addition projections for vector meson photoproduction measurements in LHC Run 3 and 4 will be presented.

Slides

- 5 March 2019, 10:30 - EMMI/KBW Lecture Hall Side room (1.17)

Ramona Vogt - Lawrence Livermore National Laboratory and University of California, Davis

Heavy flavor azimuthal correlations in cold nuclear matter

Abstract

It has been proposed that the azimuthal distributions of heavy quark-antiquark pairs may be modified in the medium of a heavy-ion collision. This assumption is tested through next-to-leading order (NLO) calculations of the azimuthal distribution including transverse momentum broadening. The differences between NLO calculations and heavy QQbar pair production in event generators are also discusssed. First, single inclusive pT distributions calculated with the exclusive HVQMNR code are compared to those calculated in the fixed-order next-to-leading logarithm approach. Next the azimuthal distributions are calculated and sensitivities to < k_T^2>, pT cut, and rapidity are studied at sqrt(s) = 7 TeV. Finally, calculations are compared to QQbar data in elementary p+p and p+pbar collisions at sqrt(s) = 7 TeV and 1.96 TeV as well as to the nuclear modification factor RpPb(pT) in p+Pb collisions at sqrt(s_NN) = 5.02 TeV measured by ALICE. While these studies were done for p+p, p+pbar and p+Pb collisions, understanding azimuthal angle correlations between heavy quarks in these smaller, colder systems is important for their interpretation in heavy-ion collisions. The low pT (pT<10 GeV) azimuthal distributions are very sensitive to the kT broadening and rather insensitive to the fragmentation function. The NLO contributions can result in an enhancement at phi ~ 0 absent any other effects. Agreement with the data was found to be good. The NLO calculations, assuming collinear factorization and introducing kT broadening, result in significant modifications of the azimuthal distribution at low pT which must be taken into account in calculations of these distributions in heavy-ion collisions.

Slides

- 5 June 2019, 13:30 - EMMI/KBW Lecture Hall (1.17)

Ulrich Heinz - The Ohio State University / J.W.Goethe-Universität

"Chemical" vs. "kinetic" freeze-out of light nuclei

Abstract

Measurements of the production of light nuclei in relativistic heavy-ion collisions present us with an apparent puzzle: While the momentum spectra of these nuclei indicate a low "kinetic freeze-out" temperature coupled with strong collective flow, their yields reflect a much higher "chemical freeze-out"temperature, consistent with the quark-gluon plasma hadronization temperature. How can these fragile nuclei "survive" the rescattering in the hadronic phase, cooling down in the process and picking up additional collective flow, without getting destroyed and depleted? I will explain how the coalescence model reconciles these observations and how recent kinetic simulations of the process support this model.

Slides

GSI Homepage, GSI Imprint (in German), GSI Privacy Policy (in German)

A. Andronic, R. Averbeck, V. Friese, B. Friman, R. Holzmann Last modified: Wed Dec 20 15:13:27 CEST 2017