1,721,045 research outputs found
Angular distributions for knockout and scattering of protons in the eikonal approximation
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Monte Carlo simulation of the Sivers effect in high-energy proton-proton collisions
No full textWe present Monte Carlo simulations of the Sivers effect in the polarized Drell-Yan pp(up arrow)->mu(+)mu X- process at the center-of-mass energy root s=200 GeV reachable at the Relativistic Heavy-Ion Collider (RHIC) of BNL. We use two different parametrizations for the Sivers function, one deduced from the analysis of semi-inclusive deep-inelastic scattering (SIDIS) data at much lower energies, and another one constrained by the RHIC data for the pp(up arrow)->pi X process at the same energy. For a given luminosity of 10(32) cm(-2) s(-1), we explore the necessary conditions to reach a statistical accuracy that allows one to extract unambiguous information on the structure of the Sivers function. In particular, we consider the feasibility of the test on its predicted universality property of changing sign when switching from SIDIS to Drell-Yan processes
Monte Carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions: The fully polarized case
No full textIn this paper, we extend the study of Drell-Yan processes with antiproton beams already presented in a previous work. We consider the fully polarized (p) over bar (up arrow)p(up arrow)->mu(+)mu(-)X process, because this is the simplest scenario for extracting the transverse spin distribution of quarks, or transversity, which is the missing piece to complete the knowledge of the nucleon spin structure at leading twist. We perform Monte Carlo simulations for transversely polarized antiproton and proton beams colliding at a center-of-mass energy of interest for the future HESR at GSI. The goal is to possibly establish feasibility conditions for an unambiguous extraction of the transversity from data on double spin asymmetries
Monte Carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
No full textThe complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan (p) over barp((up arrow))->mu(+)mu(-)X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons
Constraining quark angular momentum with the Sivers function
No full textThe determination of quark angular momentum requires the knowledge of the generalized parton distribution E in the forward limit. We assume a connection between this function and the Sivers transverse-momentum distribution, based on model calculations and theoretical considerations. Using this assumption, we show that it is possible to fit at the same time nucleon magnetic moments and semi-inclusive single-spin asymmetries. This imposes additional constraints on the Sivers function and opens a plausible way to quantifying quark angular momentum
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