# Gamma-hadron spectra in $p$ + Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV

- Institution: CERN
- Department: Conferences
- Speaker: Man Xie
- Year: 2020
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3000956)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

Under the assumption that a quark-gluon plasma droplet is produced in $p$ + A collisions, $\gamma$-triggered hadron spectra \[1,2\] are studied within a next-to-leading-order perturbative QCD parton model with the medium-modified parton fragmentation functions in $p$ + Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The initial conditions and space-time evolution of the small system of hot and dense medium is simulated by superSONIC hydrodynamic model \[3\] and parton energy loss in such a medium is described by the high-twist (HT) approach \[4\]. The scaled jet transport coefficient $\hat{q}/T^3$ in this HT approach is extracted from single hadron in central A + A collisions because its values from single and dihadron suppressions are similar \[5\]. Numerical results show that $\gamma$-hadron spectra for $p_T^\gamma=12-40$ GeV/$c$ in this scenario are suppressed by 10% $\sim$ 20% in the most central 0 - 10% $p$ + Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The suppression becomes weaker with higher transverse momentum of the triggered-$\gamma$. As a comparison, $\gamma$-hadron suppression in Pb + Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ and 5.02 TeV is also predicted.

References \[1\] X. N. Wang, Z. Huang and I. Sarcevic, Phys. Rev. Lett. 77, 231 (1996) \[2\] H. Zhang, J. F. Owens, E. Wang and X. N. Wang, Phys. Rev. Lett. 103, 032302 (2009) \[3\] R. D. Weller and P. Romatschke, Phys. Lett. B 774, 351 (2017) \[4\] W. t. Deng and X. N. Wang, Phys. Rev. C 81, 024902 (2010) \[5\] M. Xie, S. Y. Wei, G. Y. Qin and H. Z. Zhang, Eur. Phys. J. C 79, no. 7, 589 (2019).

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## Lectures

1. [Gamma-hadron spectra in $p$ + Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV](https://invisiblenetwork.ai/learn/cern/3000956/37ee551c12af), 24 min (CERN's player)