The chiral magnetic effect in heavy-ion collisions predicts an electric charge separation along the direction of a strong magnetic field, which indicates local parity ( ) and charge-conjugation-parity ( ) violation in strong interactions. We report measurements of electric charge separation signals perpendicular to the spectator event plane in Au+Au collisions using high-statistics data from RHIC Beam Energy Scan II and top-RHIC energy ( GeV) runs. A novel event shape selection method is employed to suppress the flow-induced background. The residual charge-separation signal fractions near the zero-flow limit are positive in Au+Au collisions within the 20%−50% centrality range. The significance levels are , , and at 11.5, 14.6, and 19.6 GeV, respectively. At other beam energies, the signals are either statistically limited or consistent with zero.

The measurement of two-particle Bose–Einstein momentum correlation functions are presented using $\sqrt{s_{{}_{\mathrm{NN}}}}=5.02$ TeV PbPb collision data, recorded by the CMS experiment in 2018. The measured correlation functions are discussed in terms of Lévy-type source distributions. The Lévy source parameters are extracted as functions of transverse mass and collision centrality. These source parameters include the correlation strength $\lambda$, the Lévy stability index $\alpha$, and the Lévy scale parameter R. The source shape, characterized by $\alpha$, is found to be neither Gaussian nor Cauchy. A hydrodynamic-like scaling of R is also observed.

A bstract: We report on the first measurement of the Central Exclusive Production process in proton-proton collisions: pp → ph ⁺ h ⁻ p (where h = π , K , p ) at the center-of-mass energy $$\sqrt{s}=510$$ GeV with the STAR experiment at RHIC. At this energy, the process is dominated by a double Pomeron exchange mechanism. Hence, it provides a clean environment for investigating Pomeron interactions by measuring fully reconstructed final states involving only two hadrons and two forward scattered protons. The oppositely charged hadron pairs are measured within the central detector of STAR. The forward scattered protons are measured in the Roman Pot system allowing the verification of the event’s exclusivity. Differential fiducial cross sections within the STAR acceptance are presented as a function of the difference in the azimuthal angle between the outgoing protons. The invariant masses of the charged hadron pairs are measured up to approximately 3 GeV and the square of the four-momentum transfer ( t ₁ and t ₂ ) of the two forward-scattered protons in the range 0.3 GeV ² < − t ₁ , − t ₂ < 1.6 GeV ² . The differential fiducial cross sections of the forward protons as a function of the | t ₁ + t ₂ | are also presented. All results for the π ⁺ π ⁻ pair are presented in three mass ranges. A comparison with GRANIITTI Monte Carlo predictions are also presented, where the spectra include continuum and resonant contributions. The observed spectra are consistent with double Pomeron exchange, including resonances seen in previous studies.