Abstract
Measurements are presented of associated production of a mathrm {W} boson and a charm quark (mathrm {W}+mathrm {c}) in proton–proton collisions at a center-of-mass energy of 13,text {Te}text {V}. The data correspond to an integrated luminosity of 35.7,text {fb}^{-1} collected by the CMS experiment at the CERN LHC. The mathrm {W} bosons are identified by their decay into a muon and a neutrino. The charm quarks are tagged via the full reconstruction of {mathrm {D}^{*}(2010)^{pm }} mesons that decay via {mathrm {D}^{*}(2010)^{pm }}rightarrow mathrm {D}^0 + {pi ^{pm }}rightarrow mathrm {K}^{mp } + {pi ^{pm }}+ {pi ^{pm }}. A cross section is measured in the fiducial region defined by the muon transverse momentum p_{mathrm {T}} ^{mu } > 26,text {Ge}text {V} , muon pseudorapidity |eta ^{mu } | < 2.4, and charm quark transverse momentum p_{mathrm {T}} ^{mathrm {c}} > 5,text {Ge}text {V} . The inclusive cross section for this kinematic range is sigma (mathrm {W}+mathrm {c})=1026pm 31,text {(stat)} begin{array}{c} +76 -72 end{array},text {(syst)} text { pb} . The cross section is also measured differentially as a function of the pseudorapidity of the muon from the mathrm {W} boson decay. These measurements are compared with theoretical predictions and are used to probe the strange quark content of the proton.
Highlights
Precise knowledge of the structure of the proton, expressed in terms of parton distribution functions (PDFs), is important for interpreting results obtained in proton–proton collisions at the CERN LHC
The PDFs are determined by comparing theoretical predictions obtained at a particular order in perturbative quantum chromodynamics to experimental measurements
Aprsostoocni–apterdotopnrocdoulclitsioionnsofatW√sbo=so1n3s with charm quarks in TeV is measured using the data collected by the CMS experiment in 2016 and corresponding to an integrated luminosity of 35.7 fb−1
Summary
Precise knowledge of the structure of the proton, expressed in terms of parton distribution functions (PDFs), is important for interpreting results obtained in proton–proton (pp) collisions at the CERN LHC. The flavor composition of the light quark sea in the proton and, in particular, the understanding of the strange quark distribution is important for the measurement of the W boson mass at the LHC [1]. At the LHC, the production of W or Z bosons, inclusive or associated with charm quarks, provides an important input for tests of the earlier determinations of the strange quark distribution. The associated production of W bosons and charm quarks in pp collisions at the LHC probes the strange quark content of the proton directly through the leading order (LO) processes g + s → W++c and g + s → W−+c, as shown in. This measurement was used for the first direct determination of the strange quark distribution in the proton at a hadron collider [11].
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