Speaker
Description
We study the impact of the glasma initial pre-equilibrium stage of heavy-ion collisions on heavy quarks spectra and correlations. Our main finding is that the effect of glasma on the nuclear modification factor $R_{AA}$ for the heavy quark transverse momentum spectrum is moderate, while $c\overline{c}$ angular correlations are strongly affected by the glasma [1]. Such correlations are relevant for the experimentally measurable $D\overline{D}$ angular correlations.
We numerically evaluate the classical transport equations for heavy quarks in the glasma fields, which in turn are obtained from a numerical solution of the classical field equations of motion [2]. Within this approach, we simulate the transport of $Q\overline{Q}$ pairs produced back-to-back in the glasma fields and extract their two particle correlations $\mathcal{C}(\Delta\phi,\Delta\eta)$. We focus on the azimuthal correlations $\mathcal{C}(\Delta\phi)$ and evaluate the decorrelation width $\sigma_{\Delta\phi}$ as a function of the initial quark $p_T$ and Glasma saturation momentum $Q_s$. We find that pairs with moderate $p_T$ in a glasma with sufficiently large $Q_s$ values exhibit a noticeable decorrelation already during the glasma stage. Further, we investigate how heavy quark $p_T$-spectra, initialized according to the FONLL heavy quark production cross section, are affected by the glasma fields. The strong glasma fields cause a shift in the initial spectra from low to higher $p_T$. Nevertheless, this effect on $R_{AA}$ is moderate in comparison with the nPDF contribution to the input FONLL spectra.
[1] D. Avramescu, V. Greco, T. Lappi, H. Mäntysaari, D. Müller - 2409.10565 and 2409.10564
[2] D. Avramescu, V. Băran, V. Greco, A. Ipp, D. Müller, M. Ruggieri - Phys. Rev. D 107, 114021
| Category | Theory |
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