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Nuclear Theory·nucl-th

Friday·May 11, 2018

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 10 May 2018]

    Longitudinal fluctuations and decorrelations of anisotropic flows at the LHC and RHIC energies

    Xiang-Yu Wu🇨🇳 · Long-Gang Pang🇺🇸 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳

    We perform a systematic study on the decorrelation of anisotropic flows along the pseudorapidity in relativistic heavy-ion collisions at the LHC and RHIC energies. The dynamical evolution of the QGP fireball is simulated via the CLVisc (ideal) (3+1)-dimensional hydrodynamics model, with the fully fluctuating initial condition from A-Multi-Phase-Transport (AMPT) model. Detailed analysis is performed on the longitudinal decorrelations of elliptic, triangular and quadrangular flows in terms of flow vectors, flow magnitudes and flow orientations (event planes). It is found that pure flow magnitudes have smaller longitudinal decorrelation than pure flow orientations, and the decorrelation of flow vectors is a combined effect of both flow magnitudes and orientations. The longitudinal decorrelation of elliptic flow has a strong and non-monotonic centrality dependence due to the initial elliptic collision geometry: smallest decorrelation in mid-central collisions. In contrast, the decorrelations of triangular and quadrangular flows have weak centrality dependence, slightly larger decorrelations in more peripheral collisions. Our numerical results for Pb+Pb collisions at the LHC are in good agreement with the ATLAS data, while our RHIC results predict much larger longitudinal decorrelations as compared to the LHC. We further analyze the longitudinal structures of the AMPT initial conditions and find that the final-state longitudinal decorrelation effects are strongly correlated with the lengths of the initial string structures in the AMPT model. The decorrelation effects are typically larger at lower collision energies and in more peripheral collisions due to shorter lengths of the string structures in the initial states.

    Comments:
    14 pages, 14 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1805.03762 [pdf]
    PRC(2018)·61 citations
  2. 02

    [Submitted on 10 May 2018]

    Modified Skellam, Poisson and Gaussian distributions in semi-open systems at charge-like conservation law

    Yuri Sinyukov🇺🇦

    A modification of the Skellam and Poisson distributions is proposed for subsystems when the constraints imposed by the charge conservation law in the complete system are taken into account. Such distributions can be applied, for example, for an analysis of the fluctuations of baryon and net baryon numbers in certain pseudo-rapidity interval in and collisions with high multiplicities. The presented modified Skellam, Poisson and Gaussian distributions can be utilized also in various branches of science, when one studies the fluctuations of the two variables related to a subsystem, as well as the distribution of the difference of these variables, while the mentioned difference in the total system is fixed.

    Comments:
    13 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Data Analysis, Statistics and Probability (physics.data-an)
    arXiv:
    1805.03884 [pdf]
    0 citations
  3. 03

    [Submitted on 10 May 2018]

    How to test path-length dependence in energy loss mechanisms: analysis leading to a new observable

    Magdalena Djordjevic🇷🇸 · Dusan Zigic🇷🇸 · Marko Djordjevic🇷🇸 · Jussi Auvinen🇷🇸

    When traversing QCD medium, high partons lose energy, which is typically measured by suppression, and also predicted by various energy loss models. A crucial test of different energy loss mechanisms is how the energy loss depends on the length of traversed medium (so-called path-length dependence). The upcoming experimental results will allow to, at least in principle, for the first time, clearly observe how the energy loss changes with the size of the medium, in particular, by comparing already available measurements with now upcoming data at the LHC. However, in practice, to actually perform such test, it becomes crucial to chose an optimal observable. With respect to this, a ratio of observed suppression for the two systems may seem a natural (and frequently mentioned) choice. We, however, show that extracting the path-length dependence from this observable would not be possible. We here provide an analytical derivation based on simple scaling arguments, as well as detailed numerical calculations based on our advanced energy loss framework, showing that a different observable is suitable for this purpose. We call this observable path-length sensitive suppression ratio () and provide our predictions before experimental data become available. This predictions also clearly show that this observable will allow a simple comparison of the related theoretical models with the experimental data, and consequently to distinguish between different (underlying) energy loss mechanisms, which is in turn crucial for understanding properties of created QCD medium.

    Comments:
    4 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1805.04030 [pdf]
    PRC(2019)·31 citations
  4. 04

    [Submitted on 10 May 2018]

    Dissociation of heavy quarkonium states in rapidly varying strong magnetic field

    Partha Bagchi🇨🇳 · Nirupam Dutta🇮🇳 · Souvik Priyam Adhya🇮🇳 · Bhaswar Chatterjee🇵🇱

    In a transient magnetic field, heavy quarkonium bound states evolve non adiabatically. In presence of a strong magnetic field, and become more tightly bound than we expected earlier for a pure thermal medium. We have shown that in a time varying magnetic field, there is a possibility of moderate suppression of through the non adiabatic transition to continuum where as the is so tightly bound that can not be dissociated through this process. We have calculated the dissociation probabilities up to the first order in the time dependent perturbation theory for different values of initial magnetic field intensity.

    Comments:
    4 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1805.04082 [pdf]
    Mod.Phys.Lett.A(2023)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE