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A<sc>bstract</sc> A time-dependent, flavour-tagged measurement ofCPviolation is performed withB0→ D+D−and$$ {B}_s^0 $$ →$$ {D}_s^{+}{D}_s^{-} $$ decays, using data collected by the LHCb detector in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 6 fb−1. InB0→ D+D−decays theCP-violation parameters are measured to be$$ {\displaystyle \begin{array}{c}{S}_{D^{+}{D}^{-}}=-0.552\pm 0.100\left(\textrm{stat}\right)\pm 0.010\left(\textrm{syst}\right),\\ {}{C}_{D^{+}{D}^{-}}=0.128\pm 0.103\left(\textrm{stat}\right)\pm 0.010\left(\textrm{syst}\right).\end{array}} $$ In$$ {B}_s^0 $$ →$$ {D}_s^{+}{D}_s^{-} $$ decays theCP-violating parameter formulation in terms ofϕsand|λ|results in$$ {\displaystyle \begin{array}{c}{\phi}_s=-0.086\pm 0.106\left(\textrm{stat}\right)\pm 0.028\left(\textrm{syst}\right)\textrm{rad},\\ {}\mid {\lambda}_{D_s^{+}{D}_s^{-}}\mid =1.145\pm 0.126\left(\textrm{stat}\right)\pm 0.031\left(\textrm{syst}\right).\end{array}} $$ These results represent the most precise single measurement of theCP-violation parameters in their respective channels. For the first time in a single measurement,CPsymmetry is observed to be violated inB0→ D+D−decays with a significance exceeding six standard deviations.
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Measurement of beauty-quark production in pp collisions at $$ \sqrt{s} $$ = 13 TeV via non-prompt D mesons
A<sc>bstract</sc> ThepT-differential production cross sections of non-prompt D0, D+, and$$ {\textrm{D}}_{\textrm{s}}^{+} $$ mesons originating from beauty-hadron decays are measured in proton–proton collisions at a centre-of-mass energy$$ \sqrt{s} $$ = 13 TeV. The measurements are performed at midrapidity, |y|<0.5, with the data sample collected by ALICE from 2016 to 2018. The results are in agreement with predictions from several perturbative QCD calculations. The fragmentation fraction of beauty quarks to strange mesons divided by the one to non-strange mesons,fs/(fu+fd), is found to be 0.114 ± 0.016 (stat.) ± 0.006 (syst.) ± 0.003 (BR) ± 0.003 (extrap.). This value is compatible with previous measurements at lower centre-of-mass energies and in different collision systems in agreement with the assumption of universality of fragmentation functions. In addition, the dependence of the non-prompt D meson production on the centre-of-mass energy is investigated by comparing the results obtained at$$ \sqrt{s} $$ = 5.02 and 13 TeV, showing a hardening of the non-prompt D-mesonpT-differential production cross section at higher$$ \sqrt{s} $$ . Finally, the$$ \textrm{b}\overline{\textrm{b}} $$ production cross section per unit of rapidity at midrapidity is calculated from the non-prompt D0, D+,$$ {\textrm{D}}_{\textrm{s}}^{+} $$ , and$$ {\Lambda}_{\textrm{c}}^{+} $$ hadron measurements, obtaining$$ \textrm{d}\sigma /\textrm{d}y=75.2\pm 3.2\left(\textrm{stat}.\right)\pm 5.2{\left(\textrm{syst}.\right)}_{-3.2}^{+12.3}\left(\textrm{extrap}.\right) $$ μb.
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- PAR ID:
- 10599259
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Springer
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2024
- Issue:
- 10
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/JHEP10(2024)110
