Charge-dependent pair correlations relative to a third particle in $p$+Au and $d$+Au collisions at RHIC

The STAR collaboration Adam, J. ; Adamczyk, L. ; Adams, J.R. ; et al.
Phys.Lett.B 798 (2019) 134975, 2019.
Inspire Record 1738942 DOI 10.17182/hepdata.105911

Quark interactions with topological gluon configurations can induce chirality imbalance and local parity violation in quantum chromodynamics. This can lead to electric charge separation along the strong magnetic field in relativistic heavy-ion collisions -- the chiral magnetic effect (CME). We report measurements by the STAR collaboration of a CME-sensitive observable in $p$+Au and $d$+Au collisions at 200 GeV, where the CME is not expected, using charge-dependent pair correlations relative to a third particle. We observe strong charge-dependent correlations similar to those measured in heavy-ion collisions. This bears important implications for the interpretation of the heavy-ion data.

10 data tables

The $\gamma_{OS}$ correlators in p+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC as a function of multiplicity.

The $\gamma_{SS}$ correlators in p+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC as a function of multiplicity.

The $\gamma_{OS}$ correlators in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC as a function of multiplicity.

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First observation of the directed flow of $D^{0}$ and $\overline{D^0}$ in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV

The STAR collaboration Adam, Jaroslav ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Rev.Lett. 123 (2019) 162301, 2019.
Inspire Record 1733225 DOI 10.17182/hepdata.105914

We report the first measurement of rapidity-odd directed flow ($v_{1}$) for $D^{0}$ and $\overline{D^{0}}$ mesons at mid-rapidity ($|y| < 0.8$) in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200\,GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10--80\% Au+Au collisions, the slope of the $v_{1}$ rapidity dependence ($dv_{1}/dy$), averaged over $D^{0}$ and $\overline{D^{0}}$ mesons, is -0.080 $\pm$ 0.017 (stat.) $\pm$ 0.016 (syst.) for transverse momentum $p_{\rm T}$ above 1.5~GeV/$c$. The absolute value of $D^0$-meson $dv_1/dy$ is about 25 times larger than that for charged kaons, with 3.4$\sigma$ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.

3 data tables

Directed flow $v_1$ as a function of rapidity for $D^0$ and $\bar{D^0}$ mesons at $p_T>1.5$ GeV/c for 10–80% centrality Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Directed flow $\langle v_1 \rangle$ for the combined samples of $D^0$ and $\bar{D^0}$ mesons at $p_T>1.5$ GeV/c for 10–80% centrality Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Difference in $v_1(y)$ $(\Delta v_1)$ between $D^0$ and $\bar{D^0}$ mesons at $p_T>1.5$ GeV/c for 10–80% centrality Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.