Venue: via Zoom

Time: Thursday, June, 2023, 2:15 pm

Contact: hees@itp.uni-frankfurt.de

Recently, the STAR collaboration has
presented preliminary results on the splitting of $v_1(y)$-slope ($\Delta
(\mathrm{d} v_1/\mathrm{d}y)$) between positively and negatively charged
hadrons as a function of centrality. The observed sign change of $\Delta
(\mathrm{d} v_1/\mathrm{d}y)$ with centrality is proposed as a signature
of the electromagnetic field. But, using a suitable Glauber-based initial
condition of energy and baryon distribution that captures the rapidity
dependence of directed flow of identified hadrons, we demonstrate that the
measured sign change can be described with our model of baryon stopping
without considering any electromagnetic field effects. This suggests that
baryon stopping in the initial stage serves as a large background to such
signals of the electromagnetic field. However, we have found that the
measurement of the centrality-dependent splitting of directed flow
($\Delta v_1$) between protons and antiprotons by the STAR collaboration
is extremely responsive to changes in the baryon diffusion coefficient
($\kappa_{\mathrm{B}}$) of the strongly interacting medium. Hence, we are
able to provide the first estimate of $\kappa_{\mathrm{B}}$ by
model-to-data comparison. Furthermore, we propose that the measurement of
transverse momentum differential $\Delta v_1$ can put additional
constraints on $\kappa_{\mathrm{B}}$.

Refs: arxiv : 2211.15729 (https://arxiv.org/pdf/2211.15729.pdf)

arxiv : 2211.15659 (https://arxiv.org/pdf/2211.15659.pdf)

arxiv : 2305.08806 (https://arxiv.org/pdf/2305.08806.pdf)

arxiv : 2305.10371 (https://arxiv.org/pdf/2305.10371.pdf)

The talk will be live-streamed (but not recorded) via Zoom under

https://uni-frankfurt.zoom.us/j/62522680916?pwd=M0VQeHplSFNDc0ZHbFRnK2JuZEllZz09

Transport Meeting Homepage