D. Nawarathne | Searcharxiv

arXiv2026

Binned and Unbinned Transverse Single Spin Asymmetry Extraction, including Background Subtraction and Unfolding

The determination of transverse single-spin asymmetries in experiments involving polarized targets and/or beams may encounter challenges when (1) the magnitude of the polarization varies greatly with time, (2) the polarization magnitude is not the same for each spin state, (3) different integrated luminosities occur for different spin states or different target materials, and/or (4) some kinematic variables require unfolding; these are just a few examples. We present general methods of determining the asymmetry based on both binned analysis and unbinned maximum likelihood optimization, incorporating the unfolding of kinematic variables that are smeared by detector effects, and also including the possibility of background subtraction.

hep-ex↗

arXiv2024

Measurement of $J/ψ$ and $ψ\left(2S\right)$ production in $p+p$ and $p+d$ interactions at 120 GeV

We report the $p+p$ and $p+d$ differential cross sections measured in the SeaQuest experiment for $J/ψ$ and $ψ\left(2S\right)$ production at 120 GeV beam energy covering the forward $x$-Feynman ($x_F$) range of $0.5 < x_F <0.9$. The measured cross sections are in good agreement with theoretical calculations based on the nonrelativistic QCD (NRQCD) using the long-distance matrix elements deduced from a recent global analysis of proton- and pion-induced charmonium production data. The $σ_{ψ\left(2S\right)} / σ_{J/ψ}$ cross section ratios are found to increase as $x_F$ increases, indicating that the $q \bar{q}$ annihilation process has larger contributions in the $ψ\left(2S\right)$ production than the $J/ψ$ production. The $σ_{pd}/2σ_{pp}$ cross section ratios are observed to be significantly different for the Drell-Yan process and $J/ψ$ production, reflecting their different production mechanisms. We find that the $σ_{pd}/2σ_{pp}$ ratios for $J/ψ$ production at the forward $x_F$ region are sensitive to the $\bar{d}/ \bar{u}$ flavor asymmetry of the proton sea, analogous to the Drell-Yan process. The transverse momentum ($p_T$) distributions for $J/ψ$ and $ψ\left(2S\right)$ production are also presented and compared with data collected at higher center-of-mass energies.

hep-ex↗