One of the primary goals of the spin program at the Relativistic Heavy Ion Collider (RHIC) is to determine the polarization of the sea quarks and gluons in the proton. The polarization of the sea quarks is probed through the production of $W^{-(+)}$
bosons via the annihilation of $bar{u}+d,(bar{d}+u)$, at leading order. In this proceedings we report measurements of the single-spin asymmetry, $A_{L}$, for $W$ boson production at $sqrt{s} = 510$ GeV, and the new constraints these results place on the antiquark helicity distributions. Recent results on the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive and di-jet production at $sqrt{s} = 200$ GeV are also presented. The inclusive jet results provide the first experimental indication of non-zero gluon polarization in the $x$ range probed at RHIC.
A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron bea
m, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple $qbar{q}$ pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.
We report measurements of single- and double- spin asymmetries for $W^{pm}$ and $Z/gamma^*$ boson production in longitudinally polarized $p+p$ collisions at $sqrt{s} = 510$ GeV by the STAR experiment at RHIC. The asymmetries for $W^{pm}$ were measure
d as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the protons polarized quark distributions at the scale of the $W$ mass. The results are compared to theoretical predictions, constrained by recent polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range $0.05<x<0.2$.
The production of $W$ bosons in polarized $p+p$ collisions at RHIC provides an excellent tool to probe the protons sea quark distributions. At leading order $W^{-(+)}$ bosons are produced in $bar{u}+d,(bar{d}+u)$ collisions, and parity-violating sing
le-spin asymmetries measured in longitudinally polarized $p+p$ collisions give access to the flavor-separated light quark and antiquark helicity distributions. In this proceedings we report preliminary results for the single-spin asymmetry, $A_L$ from data collected in 2012 by the STAR experiment at RHIC with an integrated luminosity of 72 pb$^{-1}$ at $sqrt{s}=510$ GeV and an average beam polarization of 56%.
We report measurements of the charge-separated $W^{+(-)} to e^{+(-)} + u_e(bar{ u}_e)$ and $Z/gamma^* to e^+e^-$ production cross sections at mid-rapidity in proton-proton collisions at $sqrt{s}$ = 500 GeV. These results are based on 13.2 pb$^{-1}$
of data recorded in 2009 by the STAR detector at RHIC. Production cross sections for W bosons that decay via the $e u$ channel were measured to be $sigma(pp to W^+ X) cdot BR(W^+ to e^+ u_e)$ = 117.3 pm 5.9(stat) pm 6.2(syst) pm 15.2(lumi) pb, and $sigma(pp to W^- X) cdot BR(W^- to e^- bar{ u}_e)$ = 43.3 pm 4.6(stat) pm 3.4(syst) pm 5.6(lumi) pb. For $Z/gamma^*$ production, $sigma(pp to Z/gamma^* X) cdot BR(Z/gamma^* to e^+ e^-)$ = 7.7 pm 2.1(stat) $^{+0.5}_{-0.9}$(syst) pm 1.0(lumi) pb for di-lepton invariant masses $m_{e^+e^-}$ between 70 and 110 GeV/$c^2$. First measurements of the W cross section ratio, $sigma(pp to W^+ X) / sigma(pp to W^- X)$, at $sqrt{s}$ = 500 GeV are also reported. Theoretical predictions, calculated using recent parton distribution functions, are found to agree with the measured cross sections.
The production of $W^{pm}$ bosons in longitudinally polarized $vec{p}+vec{p}$ collisions at RHIC provides a new means of studying the spin-flavor asymmetries of the proton sea quark distributions. Details of the $W^{pm}$ event selection in the $e^{pm
}$ decay channel at mid-rapidity are presented, along with preliminary results for the production cross section and parity-violating single-spin asymmetry, $A_L$, from the STAR Collaborations 2009 data at $sqrt{s}=500$ GeV.
