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Nuclear Theory·nucl-th

Friday·September 27, 2019

9 papers—7 primary·2 cross-listed

All9Primary7Cross-lists2
  1. 08

    [Submitted on 26 Sept 2019] (cross-list from hep-ph)

    Probing the evolution of heavy-ion collisions using direct photon interferometry

    Oscar Garcia-Montero🇩🇪 · Nicole Löher🇩🇪 · Aleksas Mazeliauskas🇩🇪 · Jürgen Berges🇩🇪 · Klaus Reygers🇩🇪

    We investigate the measurement of Hanbury Brown-Twiss (HBT) photon correlations as an experimental tool to discriminate different sources of photon enhancement, which are proposed to simultaneously reproduce the direct photon yield and the azimuthal anisotropy measured in nuclear collisions at RHIC and the LHC. To showcase this, we consider two different scenarios in which we enhance the yields from standard hydrodynamical simulations. In the first, additional photons are produced from the early pre-equilibrium stage computed from the \textit{bottom-up} thermalization scenario. In the second, the thermal rates are enhanced close to the pseudo-critical temperature using a phenomenological ansatz. We compute the correlators for relative momenta and for different transverse pair momenta, , and find that the longitudinal correlation is the most sensitive to different photon sources. Our results also demonstrate that including anisotropic pre-equilibrium rates enhances non-Gaussianities in the correlators, which can be quantified using the kurtosis of the correlators. Finally, we study the feasibility of measuring a direct photon HBT signal in the upcoming high-luminosity LHC runs. Considering only statistical uncertainties, we find that with the projected heavy ion events a measurement of the HBT correlations for is statistically significant.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1909.12246 [pdf]
    PRC(2020)·24 citations
  2. 09

    [Submitted on 26 Sept 2019] (cross-list from hep-ph)

    Non-equilibrium photons from the bottom-up thermalization scenario

    Oscar Garcia-Montero🇩🇪

    In this work, I calculate the resolved spectra for the three stages of the \textit{bottom-up} scenario, which are comparable to the thermal contribution, particularly at higher values of the saturation scale . Analytical solutions are obtained by including a parametrization of scaling solutions from far-from-equilibrium classical statistical lattice simulations into a small angle kinetic rate. Furthermore, a theoretically motivated ansatz is used to account for near-collinear enhancement of the low- radiation. The system is phenomenologically constrained using the charge hadron multiplicities from LHC and RHIC as in previous parametric estimates and fair agreement with the data available for photons was found. I find that for this realistic set of parameters, the contribution from the thermalizing glasma dominates the excess photons.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1909.12294 [pdf]
    Annals Phys.(2022)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE