Abstract
Until now, the Cabibbo Kobayashi Maskawa matrix element, |Vcb|, has always been measured in B decays, i.e. at an energy scale \( {q}_b\sim \frac{m_b}{2} \), far below the weak scale. We consider here the possibility of measuring it close to the weak scale, at qW ∼ mW, in top decays at the Large Hadron Collider (LHC). Our proposed method would use data from the LHC experiments in hadronic top decays \( t\to b{W}^{+}\to b\overline{b}c \), tagged by the semileptonic decay of the associated top. We estimate the uncertainty of such a measurement, as a function of present and potential future experimental jet flavour-tagging performances, and conclude that first measurements using the data collected during 2016-2018 could yield a fractional error on |Vcb| of order 7% per experiment. We also give projected performances at higher luminosities, representative of those anticipated at LHC Run 3 and HL-LHC.
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References
Particle Data Group collaboration, Review of particle physics, Phys. Rev. D 98 (2018) 030001 [INSPIRE].
S. Descotes-Genon, A. Falkowski, M. Fedele, M. González-Alonso and J. Virto, The CKM parameters in the SMEFT, arXiv:1812.08163 [INSPIRE].
ATLAS collaboration, Measurement of the \( t\overline{t} \) production cross-section using eμ events with b-tagged jets in pp collisions at \( \sqrt{s}=13 \) TeV with the ATLAS detector, Phys. Lett. B 761 (2016)136 [Erratum ibid. B 772 (2017) 879] [arXiv:1606.02699] [INSPIRE].
CMS collaboration, Measurement of the \( t\overline{t} \) production cross section using events with one lepton and at least one jet in pp collisions at \( \sqrt{s}=13 \) TeV, JHEP 09 (2017) 051 [arXiv:1701.06228] [INSPIRE].
ATLAS collaboration, Measurements of top-quark pair differential cross-sections in the lepton+jets channel in pp collisions at \( \sqrt{s}=13 \) TeV using the ATLAS detector, JHEP 11 (2017) 191 [arXiv:1708.00727] [INSPIRE].
CMS collaboration, Measurement of differential cross sections for the production of top quark pairs and of additional jets in lepton+jets events from pp collisions at \( \sqrt{s}=13 \) TeV, Phys. Rev. D 97 (2018) 112003 [arXiv:1803.08856] [INSPIRE].
ATLAS collaboration, Measurement of the inclusive and fiducial \( t\overline{t} \) production cross-sections in the lepton+jets channel in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, Eur. Phys. J. C 78 (2018) 487 [arXiv:1712.06857] [INSPIRE].
ATLAS collaboration, Optimisation of the ATLAS b-tagging performance for the 2016 LHC run, ATL-PHYS-PUB-2016-012, CERN, Geneva, Switzerland (2016).
CMS collaboration, Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV, 2018 JINST 13 P05011 [arXiv:1712.07158] [INSPIRE].
ATLAS collaboration, Measurements of b-jet tagging efficiency with the ATLAS detector using \( t\overline{t} \) events at \( \sqrt{s}=13 \) TeV, JHEP 08 (2018) 089 [arXiv:1805.01845] [INSPIRE].
ATLAS collaboration, Measurement of b-tagging efficiency of c-jets in \( t\overline{t} \) events using a likelihood approach with the ATLAS detector, ATLAS-CONF-2018-001, CERN, Geneva, Switzerland (2018).
ATLAS collaboration, Calibration of light-flavour jet b-tagging rates on ATLAS proton-proton collision data at \( \sqrt{s}=13 \) TeV, ATLAS-CONF-2018-006, CERN, Geneva, Switzerland (2018).
ATLAS collaboration, Search for the decay of the Higgs boson to charm quarks with the ATLAS experiment, Phys. Rev. Lett. 120 (2018) 211802 [arXiv:1802.04329] [INSPIRE].
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Harrison, P.F., Vladimirov, V. A method to determine |Vcb| at the weak scale in top decays at the LHC. J. High Energ. Phys. 2019, 191 (2019). https://doi.org/10.1007/JHEP01(2019)191
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DOI: https://doi.org/10.1007/JHEP01(2019)191