Itzhak Tserruya

A bstract: The BM@N experiment (Baryonic Matter at the Nuclotron) is the first fixed-target experiment at the JINR NICA accelerator complex. In this work, data on the interactions of a carbon-ion beam with kinetic energies of 4.0A GeV and 4.5A GeV with C, Al, Cu, and Pb targets are used to measure transverse momentum spectra and rapidity distributions of Λ hyperon yields. The results are compared with the predictions of DCM-SMM, UrQMD, and PHSD transport models and with the Λ yield measurements in other experiments at similar collision energies.

We present the first measurements of the forward and midrapidity η -meson cross sections from p + p collisions at s = 500 and 510 GeV, respectively. We also report the midrapidity η / π 0 ratio at 510 GeV. The forward cross section is measured differentially in η -meson transverse momentum ( p T ) from 1.0 to 6.5 GeV / c for pseudorapidity 3.0 < | η | < 3.8 . The midrapidity cross section is measured from 3.5 to 44 GeV / c for pseudorapidity | η | < 0.35 . Both cross sections serve as critical inputs to an updated global analysis of the η -meson fragmentation functions.

Utilizing the 2012 transversely polarized proton data from the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, the forward η -meson transverse single-spin asymmetry ( A N ) was measured for p ↑ + p collisions at s = 200 GeV as a function of Feynman-x ( x F ) for 0.2 < | x F | < 0.8 and transverse momentum ( p T ) for 1.0 < p T < 5.0 GeV / c . Large asymmetries at positive x F are observed ( ⟨ A N ⟩ = 0.086 ± 0.019 ), agreeing well with previous measurements of π 0 and η A N , but with reach to higher x F and p T . The contribution of initial-state spin-momentum correlations to the asymmetry, as calculated in the collinear twist-3 framework, appears insufficient to describe the data.

Recent measurements of J / ψ production as a function of event charged-particle multiplicity at the collision energies of both the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) show enhanced J / ψ production yields with increasing multiplicity. One potential explanation for this type of dependence is multiparton interactions (MPI). We present the first study of potential autocorrelations at RHIC energies and forward and backward rapidity of self-normalized J / ψ yields and ψ ( 2 S ) to J / ψ ratio, as a function of self-normalized multiplicity in p + p collisions. In addition, detailed studies tuned to RHIC energies were performed to investigate the MPI impacts. We find that the PHENIX data at RHIC are consistent with recent LHC measurements and can only be described by calculations that include MPI effects. The forward and backward ψ ( 2 S ) to J / ψ ratio is found to be less dependent on the charged-particle multiplicity.

Results of the BM@N experiment at the Nuclotron/NICA complex on the production of protons, deuterons and tritons in interactions of an argon beam of 3.2 A GeV with fixed targets of C, Al, Cu, Sn and Pb are presented. Transverse mass spectra, rapidity distributions and multiplicities of protons, deuterons and tritons are measured. The results are treated within a coalescence approach and compared with predictions of theoretical models and with other measurements.