Nuclear and Quark Matter Seminar 2019

Dates:
07.02. | 05.03. | 05.06. | 01.07. | 19.07. | 14.08. | 09.09. | 22.10. | 02.12. |

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

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• 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

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• 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.

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• 1 July 2019, 14:30 - EMMI/KBW Lecture Hall Side room (1.17)
  
  Prabhat Pujahari - Indian Institute of Technology Chennai
  Collectivity in hadronic systems at the LHC
  
  Abstract
  Hydrodynamics as a tool to describe the space-time evolution of the expanding matter and extract its properties has been a centrepiece of heavy ion physics essentially since its inception. It experienced a renaissance around 2010 when the importance of the initial state geometry and its event-by-event fluctuations finally became clear. In this talk, I will present the first comparison of anisotropy harmonics and event-by-event correlations of different orders between p-p, p-Pb and Pb-Pb as a function of multiplicity. These new data provide important insights into the origin of collectivity observed in small collision systems.

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• 19 July 2019, 13:30 - EMMI/KBW Lecture Hall Side room (1.17)
  
  Anthony Timmins - University of Houston
  The structure of the nucleus and proton at the LHC
  
  Abstract
  A variety of measurements from collisions of large and small systems are sensitive to the spatial configuration of the initial state of those systems. One important example is measurements of anisotropic flow, which carries information regarding the initial state eccentricity. To this end, I will review such measurements from the LHC running periods 1 and 2, and discuss their implications for state of the art initial state calculations. I will also discuss prospects for LHC running period 3, where much larger data samples will be collected, and a greater variety of nuclear species are expected to be collided.
  Slides

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• 14 August 2019, 13:30 - Theory Seminar Room (BZ SB3 3.170a)
  
  Sudhir Rode - Indian Institute of Technology Indore
  Open heavy-flavour production with ALICE at the LHC
  
  Abstract
  Heavy flavours are a crucial and well known probe to study the nature of the strongly interacting matter created in ultrarelativistic heavy-ion collisions, the so-called Quark Gluon Plasma (QGP). Investigating their production in proton-proton and proton-Pb collisions along with heavy-ion collisions is very important since the heavy quarks are produced at the early stages of the collision. Heavy-flavour hadrons can be measured via their hadronic and semileptonic decay channels. Here, recent results from ALICE will be presented, including the production cross section of open heavy-flavours in pp collisons and the nuclear modification factors of open heavy flavour in p-Pb and Pb-Pb collisions. The mass dependent energy loss of quarks in the QGP medium will be discussed.
  Slides

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• 9 September 2019, 16:15 - Theory Seminar Room (BZ SB3 3.170a)
  
  John Jowett - CERN
  Outlook for heavy-ion collisions in the LHC after Run 2
  
  Abstract
  LHC Run 2 ended with the 2018 Pb-Pb collision run, during which a luminosity 6 times beyond the design was achieved. With similar performance in multiple conditions for p-Pb collisions in 2016 and a pilot Xe-Xe run in 2017, many of the goals for the high luminosity phase in Run 3 and Run 4 are already in hand. I will review the prospects and report on plans to add O-O and p-O collisions in Run 3.
  Slides

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• 22 October 2019, 14:30 - Seminar Room (KBW 2.28)
  
  Ramona Lea - University and INFN Trieste
  Production of light (anti-) nuclei and (anti-)hypernuclei with ALICE at the LHC
  
  Abstract
  The high energy pp, p-Pb, and Pb-Pb collisions at the LHC offer a unique tool to study the production of nuclei and the corresponding anti-particles and of hyperon-baryon bound systems, called hypernuclei. The study of the production yield of (anti-)(hyper-)nuclei in heay-ion collisions at the LHC energy can help to probe the late stages in the evolution of the hot, dense nuclear matter created in the collision and serves as baseline for the search of exotic multi-baryon states. The measurements in smaller collision systems have direct connections to cosmological and astrophysical studies, in particular for the search of dark matter candidates where one possible signal is the increased flux of light anti-nuclei which has an interplay with the measurement in in pp and p-A collisions. Thanks to its excellent particle identification and tracking capabilities, the ALICE detector allows for the measurement of deuterons, tritons, 3He, 4He and their corresponding anti-nuclei. Moreover, the secondary vertices from the mesonic decays of (anti-)hypernuclei can be reconstructed. Results on the production yields of light nuclei and anti-nuclei in pp, p-Pb, and Pb-Pb collisions will be presented, together with the measurements of hypertriton lifetime and production rates in Pb-Pb collisions. The experimental results will be compared to the predictions of statistical (thermal) model and baryon coalescence models. Further constraints on the production mechanism of light nuclei are obtained from measurements of the elliptic flow of light-nuclei and their comparison to expectations from coalescence and hydrodynamic models.
  Slides

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• 2 December 2019, 13:30 - EMMI/KBW Lecture Hall (1.17)
  
  Various Presenters
  Highlights of the Quark Matter 2019 conference
  
  Abstract
  Selected highlights presented at the recent Quark Matter conference will be discussed.
  
  Program:
  Szymon Harabasz: Production of light nuclei
  Paula Hillmann: New results on collectivity
  Viktor Klochkov: New results on CME / magnetic field
  Anton Motornenko: QCD matter at finite density
  Andrea Dubla: New results on heavy flavor
  Hannah Elfner: Jet cone size dependence
  Florian Seck: Measurements of the process gamma gamma -> e+ e-
  Justin Mohs: Bayesian contraints on transport coefficients

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