Study of $W$ boson production in association with beauty and charm

The LHCb collaboration Aaij, Roel ; Adeva, Bernardo ; Adinolfi, Marco ; et al.
Phys.Rev. D92 (2015) 052001, 2015.
Inspire Record 1370436 DOI 10.17182/hepdata.73718

The associated production of a W boson with a jet originating from either a light parton or heavy-flavor quark is studied in the forward region using proton-proton collisions. The analysis uses data corresponding to integrated luminosities of 1.0 and 2.0  fb-1 collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, respectively. The W bosons are reconstructed using the W→μν decay and muons with a transverse momentum, pT, larger than 20 GeV in the pseudorapidity range 2.0<η<4.5. The partons are reconstructed as jets with pT>20  GeV and 2.2<η<4.2. The sum of the muon and jet momenta must satisfy pT>20  GeV. The fraction of W+jet events that originate from beauty and charm quarks is measured, along with the charge asymmetries of the W+b and W+c production cross sections. The ratio of the W+jet to Z+jet production cross sections is also measured using the Z→μμ decay. All results are in agreement with Standard Model predictions.

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Measurement of forward W and Z boson production in $pp$ collisions at $ \sqrt{s}=8 $ TeV

The LHCb collaboration Aaij, Roel ; Abellán Beteta, Carlos ; Adeva, Bernardo ; et al.
JHEP 1601 (2016) 155, 2016.
Inspire Record 1406555 DOI 10.17182/hepdata.71419

Measurements are presented of electroweak boson production using data from pp collisions at a centre-of-mass energy of $ \sqrt{s}=8 $ TeV. The analysis is based on an integrated luminosity of 2.0 fb$^{−1}$ recorded with the LHCb detector. The bosons are identified in the W → μν and Z → μ$^{+}$ μ$^{−}$ decay channels. The cross-sections are measured for muons in the pseudorapidity range 2.0 < η < 4.5, with transverse momenta p$_{T}$ > 20 GeV/c and, in the case of the Z boson, a dimuon mass within $ 60 < {M}_{\mu }{{{}_{{}^{+}}}_{\mu}}_{{}^{-}}<120 $ GeV/c$^{2}$. The results are $ {\sigma}_W{{}_{{}^{+}}}_{\to \mu }{{}_{{}^{+}}}_{\nu }=1093.6\pm 2.1\pm 7.2\pm 10.9\pm 12.7\ \mathrm{p}\mathrm{b}, $ $ {\sigma}_W{{}_{{}^{-}}}_{\to \mu }{{}_{{}^{-}}}_{\overline{\nu}}=818.4\pm 1.9\pm 5.0\pm 7.0\pm 9.5\ \mathrm{p}\mathrm{b}, $ $ {\sigma}_{\mathrm{Z}\to \mu }{{{}_{{}^{+}}}_{\mu}}_{{}^{-}}=95.0\pm 0.3\pm 0.7\pm 1.1\pm 1.1\ \mathrm{p}\mathrm{b}, $ $ {\sigma}_{Z\to \mu }{{{}_{{}^{+}}}_{\mu}}_{{}^{-}}=95.0\pm 0.3\pm 0.7\pm 1.1\pm 1.1\ \mathrm{p}\mathrm{b}, $ where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. The evolution of the W and Z boson cross-sections with centre-of-mass energy is studied using previously reported measurements with 1.0 fb$^{−1}$ of data at 7 TeV. Differential distributions are also presented. Results are in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics.

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Study of the production of $\Lambda_b^0$ and $\overline{B}^0$ hadrons in $pp$ collisions and first measurement of the $\Lambda_b^0\rightarrow J/\psi pK^-$ branching fraction

The LHCb collaboration Aaij, R. ; Adeva, Bernardo ; Adinolfi, Marco ; et al.
Chin.Phys. C40 (2016) 011001, 2016.
Inspire Record 1391317 DOI 10.17182/hepdata.75485

The product of the differential production cross-section and the branching fraction of the decay is measured as a function of the beauty hadron transverse momentum, p(T), and rapidity, y. The kinematic region of the measurements is p(T) < 20 GeV/c and 2.0 < y < 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3fb(−)(1) collected by the LHCb detector in pp collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb results of the fragmentation fraction ratio the branching fraction of the decay is measured to bewhere the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B̅(0) → J/ψK̅*(892)(0), and the fourth is due to the knowledge of . The sum of the asymmetries in the production and decay between and is also measured as a function of p(T) and y. The previously published branching fraction of , relative to that of , is updated. The branching fractions of are determined.

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