Measurement of parity-violating spin asymmetries inW±production at midrapidity in longitudinally polarizedp+p

Single-spin asymmetry ofJ/ψproduction inp+p,p+Al, andAidala1, Akiba2, Alfred3 et al. 2018Phys. Rev. DSelf Cite211180View full textAdd to dashboardCite

“…The background fraction f was obtained using the Gaussian process regression (GPR) method [56][57][58][59] for each p T and x F bin. The GPR method is a nonparametric regression approach considered to be less biased and has been used in several previous PHENIX measurements [55,60]. Figure 2 shows the fitting result with the GPR method using p þ Au data.…”

Cross section and longitudinal single-spin asymmetry AL for forward W±→μ±ν production in polarized Adare1, Aidala2, Ajitanand3 et al. 2018Phys. Rev. DSelf Cite

“…At forward μ − rapidities, the DSSV08 curves for two scenarios in which ΔdðxÞ=dðxÞ approaches unity when x is approaching unity are also displayed for comparison. The previously published central WðþZÞ → e asymmetries from the STAR experiment [11] and PHENIX [13] are also shown. The 2013 results from STAR are still expected [28].…”

“…The curves depict helicity PDF parametrizations from various global fits described in the text that are calculated using the polarized NLO generator CHE. AE → μ AE ν cross section measured at forward and backward rapidity from this measurement averaged over both arms 1.1 < jηj < 2.5 (blue solid circles) and central rapidity measurements from PHENIX−0.35 < η < 0.35 (blue solid triangles) [13] and STAR−1.0 < η < 1.0 (green solid stars) [11]. The horizontal bars and yellow shading show the statistical and systematic uncertainties, respectively.…”

“…This larger unpolarized contribution could explain our surprisingly small backward W þ asymmetries. [13]. The STAR results (green solid stars) [11] are for combined 2011 þ 2012.…”

“…At central rapidities, W decay electrons are reconstructed, while at forward rapidities (1.1 < jηj < 2.6 and 1.1 < jηj < 2.5 for the north and south muon arms, respectively) decay muons are being studied. Recent results by STAR [11] and PHENIX [12,13] for the electron channels exist. In this paper, the first asymmetry measurement using muons and at forward/ backward rapidities is reported.…”