Observation of nuclear modifications in W$^\pm$ boson production in pPb collisions at $\sqrt{s_\mathrm{NN}} =$ 8.16 TeV

The CMS collaboration
No Journal Information, 2019

Abstract (data abstract)
CERN-LHC. The production of W bosons is studied in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of $\sqrt{{s}_\textrm{NN}} = 8.16$ TeV. Measurements are performed in the $\textrm{W}^{\pm}\to\mu^{\pm}\nu$ channel using a data sample corresponding to an integrated luminosity of $173.4 \pm 8.7 \textrm{nb}^{-1}$, collected by the CMS Collaboration at the LHC. The number of positively and negatively charged W bosons is determined separately in the muon pseudorapidity region in the laboratory frame $|\eta_{\textrm{lab}}^{\mu}|<2.4$ and transverse momentum $p_{\textrm{T}}^{\mu}>25$~GeV/$c$. The $\textrm{W}^{\pm}$ boson differential cross sections, muon charge asymmetry, and the ratios of $\textrm{W}^{\pm}$ boson yields for the proton-going over the Pb-going beam directions are reported as a function of the muon pseudorapidity in the nucleon-nucleon centre-of-mass frame. The measurements are compared to the predictions from theoretical calculations based on parton distribution functions (PDFs) at next-to-leading-order. The results favour PDF calculations that include nuclear modifications and provide constraints on the nuclear PDF global fits.

  • Table 1

    Data from Figure 4

    10.17182/hepdata.88284.v1/t1

    Muon charge asymmetry, $(N_{\mu}^{+} - N_{\mu}^{-})/(N_{\mu}^{+} + N_{\mu}^{-})$, as a function of the muon pseudorapidity in the centre-of-mass frame.

  • Table 2

    Data from Figure 2 a

    10.17182/hepdata.88284.v1/t2

    Differential production cross sections for $\textrm{pPb} \to W^{+} + X \to \mu^{+} \nu + X$ for positively charged muons of...

  • Table 3

    Data from Figure 2 b

    10.17182/hepdata.88284.v1/t3

    Differential production cross sections for $\textrm{pPb} \to W^{-} + X \to \mu^{-} \bar{\nu} + X$ for negatively charged muons of...

  • Table 4

    Data from Figure 3 b

    10.17182/hepdata.88284.v1/t4

    Forward-backward ratio, $N_{\mu}(+\eta_{\textrm{CM}})/N_{\mu}(-\eta_{\textrm{CM}})$, for the negatively charged muons, as a function of the muon pseudorapidity in the centre-of-mass frame.

  • Table 5

    Data from Figure 3 a

    10.17182/hepdata.88284.v1/t5

    Forward-backward ratio, $N_{\mu}(+\eta_{\textrm{CM}})/N_{\mu}(-\eta_{\textrm{CM}})$, for the positively charged muons, as a function of the muon pseudorapidity in the centre-of-mass frame.

  • Table 6

    Data from Figure 3 c

    10.17182/hepdata.88284.v1/t6

    Forward-backward ratio, $N_{\mu}(+\eta_{\textrm{CM}})/N_{\mu}(-\eta_{\textrm{CM}})$, for muons of both signs, as a function of the muon pseudorapidity in the centre-of-mass frame.

  • Table 7

    Covariance matrix for the data from Figure 2

    10.17182/hepdata.88284.v1/t7

    The covariance matrix of the W boson differential cross section measurements. Each bin is labeled mi_i or pl_i, where mi...

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