We report measurements of the charge-separated W+(−)→e+(−)+νe(νˉe)W^{+(-)} o e^{+(-)} + u_e(ar{ u}_e)W+(−)→e+(−)+νe(νˉe) and Z/γ∗→e+e−Z/gamma^* o e^+e^-Z/γ∗→e+e− production cross sections at mid-rapidity in proton-proton collisions at ssqrt{s}s = 500 GeV. These results are based on 13.2 pb−1^{-1}−1 of data recorded in 2009 by the STAR detector at RHIC. Production cross sections for W bosons that decay via the eνe ueν channel were measured to be σ(pp→W+X)⋅BR(W+→e+νe)sigma(pp o W^+ X) cdot BR(W^+ o e^+ u_e)σ(pp→W+X)⋅BR(W+→e+νe) = 117.3 pm 5.9(stat) pm 6.2(syst) pm 15.2(lumi) pb, and σ(pp→W−X)⋅BR(W−→e−νˉe)sigma(pp o W^- X) cdot BR(W^- o e^- ar{ u}_e)σ(pp→W−X)⋅BR(W−→e−νˉe) = 43.3 pm 4.6(stat) pm 3.4(syst) pm 5.6(lumi) pb. For Z/γ∗Z/gamma^*Z/γ∗ production, σ(pp→Z/γ∗X)⋅BR(Z/γ∗→e+e−)sigma(pp o Z/gamma^* X) cdot BR(Z/gamma^* o e^+ e^-)σ(pp→Z/γ∗X)⋅BR(Z/γ∗→e+e−) = 7.7 pm 2.1(stat) −0.9+0.5^{+0.5}_{-0.9}−0.9+0.5(syst) pm 1.0(lumi) pb for di-lepton invariant masses me+e−m_{e^+e^-}me+e− between 70 and 110 GeV/c2c^2c2. First measurements of the W cross section ratio, σ(pp→W+X)/σ(pp→W−X)sigma(pp o W^+ X) / sigma(pp o W^- X)σ(pp→W+X)/σ(pp→W−X), at ssqrt{s}s = 500 GeV are also reported. Theoretical predictions, calculated using recent parton distribution functions, are found to agree with the measured cross sections.
Measurement of the $W o e u$ and $Z/gamma^* o e^+e^-$ Production Cross Sections at Mid-rapidity in Proton-Proton Collisions at $sqrt{s}$ = 500 GeV
S. FazioInvestigation
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2012-01-01
Abstract
We report measurements of the charge-separated W+(−)→e+(−)+νe(νˉe)W^{+(-)} o e^{+(-)} + u_e(ar{ u}_e)W+(−)→e+(−)+νe(νˉe) and Z/γ∗→e+e−Z/gamma^* o e^+e^-Z/γ∗→e+e− production cross sections at mid-rapidity in proton-proton collisions at ssqrt{s}s = 500 GeV. These results are based on 13.2 pb−1^{-1}−1 of data recorded in 2009 by the STAR detector at RHIC. Production cross sections for W bosons that decay via the eνe ueν channel were measured to be σ(pp→W+X)⋅BR(W+→e+νe)sigma(pp o W^+ X) cdot BR(W^+ o e^+ u_e)σ(pp→W+X)⋅BR(W+→e+νe) = 117.3 pm 5.9(stat) pm 6.2(syst) pm 15.2(lumi) pb, and σ(pp→W−X)⋅BR(W−→e−νˉe)sigma(pp o W^- X) cdot BR(W^- o e^- ar{ u}_e)σ(pp→W−X)⋅BR(W−→e−νˉe) = 43.3 pm 4.6(stat) pm 3.4(syst) pm 5.6(lumi) pb. For Z/γ∗Z/gamma^*Z/γ∗ production, σ(pp→Z/γ∗X)⋅BR(Z/γ∗→e+e−)sigma(pp o Z/gamma^* X) cdot BR(Z/gamma^* o e^+ e^-)σ(pp→Z/γ∗X)⋅BR(Z/γ∗→e+e−) = 7.7 pm 2.1(stat) −0.9+0.5^{+0.5}_{-0.9}−0.9+0.5(syst) pm 1.0(lumi) pb for di-lepton invariant masses me+e−m_{e^+e^-}me+e− between 70 and 110 GeV/c2c^2c2. First measurements of the W cross section ratio, σ(pp→W+X)/σ(pp→W−X)sigma(pp o W^+ X) / sigma(pp o W^- X)σ(pp→W+X)/σ(pp→W−X), at ssqrt{s}s = 500 GeV are also reported. Theoretical predictions, calculated using recent parton distribution functions, are found to agree with the measured cross sections.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
