# EP Articles

Najnovije dodano:
2020-01-10
10:58
 Measurement of $|V_{cb}|$ with $B_s^0 \to D_s^{(*)-} \mu^+ \nu_{\mu}$ decays / LHCb Collaboration The element $|V_{cb}|$ of the Cabibbo-Kobayashi-Maskawa matrix is measured using semileptonic $B_s^0$ decays produced in proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. Rates of $B_s^0 \to D_s^{-} \mu^+ \nu_{\mu}$ and $B_s^0 \to D_s^{*-} \mu^+ \nu_{\mu}$ decays are analyzed using hadronic form-factor parametrizations derived either by Caprini, Lellouch and Neubert (CLN) or by Boyd, Grinstein and Lebed (BGL). [...] arXiv:2001.03225; LHCb-PAPER-2019-041; CERN-EP-2019-282; LHCB-PAPER-2019-041.- Geneva : CERN, 2020-04-21 - 25 p. - Published in : Phys. Rev. D 101 (2020) 072004 Article from SCOAP3: PDF; Fulltext: LHCb-PAPER-2019-041 - PDF; 2001.03225 - PDF; Related data file(s): ZIP; Supplementary material: ZIP;

2020-01-06
15:42
 First observation of excited $\Omega_b^-$ states / LHCb Collaboration We report four narrow peaks in the $\Xi_b^0K^-$ mass spectrum obtained using $pp$ collisions at center-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 9 fb$^{-1}$ recorded by the LHCb experiment. Referring to these states by their mass, the mass values are \begin{align*} m(\Omega_b(6316)^-) &= 6315.64\pm0.31\pm0.07\pm0.50 {\rm MeV}, \\ m(\Omega_b(6330)^-) &= 6330.30\pm0.28\pm0.07\pm0.50 {\rm MeV}, \\ m(\Omega_b(6340)^-) &= 6339.71\pm0.26\pm0.05\pm0.50 {\rm MeV}, \\ m(\Omega_b(6350)^-) &= 6349.88\pm0.35\pm0.05\pm0.50 {\rm MeV}, \end{align*}where the uncertainties are statistical, systematic and the last is due to the knowledge of the $\Xi_b^0$ mass. [...] arXiv:2001.00851; LHCb-PAPER-2019-042; CERN-EP-2019-278; LHCB-PAPER-2019-042.- Geneva : CERN, 2020-02-26 - 12 p. - Published in : Phys. Rev. Lett. 124 (2020) 082002 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-12-18
08:58
 Test of lepton universality with $\Lambda^{0}_{b} \to p K^- \ell^+ \ell^-$ decays / LHCb Collaboration The ratio of branching fractions of the decays $\Lambda^{0}_{b}\to pK^{-}e^{+}e^{-}$ and $\Lambda^{0}_{b}\to pK^{-}\mu^{+}\mu^{-}$, $R^{-1}_{pK}$, is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb$^{-1}$ recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared range $0.1 < q^{2} < 6.0$ $GeV^{2}/c^{4}$ and the $pK^{-}$ mass range $m(pK^{-}) < 2600$ $MeV/c^{2}$, the ratio of branching fractions is measured to be $R^{-1}_{pK} = 1.17 ^{+0.18}_{-0.16} \pm 0.07$, where the first uncertainty is statistical and the second systematic. [...] arXiv:1912.08139; LHCb-PAPER-2019-040; CERN-EP-2019-272; LHCB-PAPER-2019-040; LHCB-PAPER-2019-040-003; LHCB-PAPER-2019-040.- Geneva : CERN, 2020-05-11 - 26 p. - Published in : JHEP 2020 (2020) 040 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-12-09
13:47
 Measurement of $CP$ violation in $B^0\to D^{*\pm} D^{\mp}$ decays / LHCb Collaboration The decay-time-dependent $CP$ asymmetry in $B^0 \to D^{*\pm}D^{\mp}$ decays is measured using a data set corresponding to an integrated luminosity of$9$fb$^{-1}$ recorded by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The $CP$ parameters are measured as $S_{D^*D} = -0.861 \pm 0.077\,\text{(stat)} \pm 0.019 \,\text{(syst)}\,,$ $\Delta S_{D^*D} = 0.019 \pm 0.075 \,\text{(stat)} \pm 0.012 \,\text{(syst)}\,,$ $C_{D^*D} = -0.059 \pm 0.092 \,\text{(stat)} \pm 0.020 \,\text{(syst)} \,,$ $\Delta C_{D^*D} = -0.031 \pm 0.092 \,\text{(stat)} \pm 0.016\,\text{(syst)} \,,$ ${\cal A}_{D^*D} = 0.008 \pm 0.014 \,\text{(stat)} \pm 0.006\,\text{(syst)}\,. [...] arXiv:1912.03723; CERN-EP-2019-264; LHCB-PAPER-2019-036.- 2020-03-25 - 28 p. - Published in : JHEP 2003 (2020) 147 Fulltext: LHCb-PAPER-2019-036 - PDF; 1912.03723 - PDF; Related data file(s): ZIP; Supplementary information: ZIP; External link: Fulltext from publisher 2019-12-05 10:43  Isospin amplitudes in$\Lambda_b^0\to J/\psi \Lambda(\Sigma^0)$and$\Xi_b^0\to J/\psi \Xi^0(\Lambda)$decays / LHCb Collaboration Ratios of isospin amplitudes in hadron decays are a useful probe of the interplay between weak and strong interactions, and allow searches for physics beyond the Standard Model. We present the first results on isospin amplitudes in$b$-baryon decays, using data corresponding to an integrated luminosity of 8.5 fb$^{-1}$, collected with the LHCb detector in$pp$collisions at center of mass energies of 7, 8 and 13 TeV. [...] arXiv:1912.02110; CERN-EP-2019-268; LHCb-PAPER-2019-039; LHCB-PAPER-2019-039-003; LHCB-PAPER-2019-039.- Geneva : CERN, 2020-03-17 - 11 p. - Published in : Phys. Rev. Lett. 124 (2020) 111802 Fulltext: 1912.02110 - PDF; DI-PRL-cascade - PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; 2019-11-21 13:46  Precision measurement of the$\Xi_{cc}^{++}$mass / LHCb Collaboration A measurement of the$\Xi_{cc}^{++}$mass is performed using data collected by the LHCb experiment between 2016 and 2018 in$pp$collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6$\mathrm{fb}^{-1}$. The$\Xi_{cc}^{++}$candidates are reconstructed via the decay modes$\Xi_{cc}^{++}\to\Lambda_c^+K^-\pi^+\pi^+$and$\Xi_{cc}^{++}\to\Xi_c^+\pi^+$. [...] arXiv:1911.08594; LHCb-PAPER-2019-037; CERN-EP-2019-258; LHCB-PAPER-2019-037.- 2020-02-07 - 18 p. - Published in : JHEP 2002 (2020) 049 Article from SCOAP3: PDF; Fulltext: LHCb-PAPER-2019-037_arXiv - PDF; 1911.08594 - PDF; Related data file(s): ZIP; Supplementary Information: ZIP; 2019-11-20 14:12  Observation of the semileptonic decay$B^{+}\to p\overline{p}\mu^{+}\nu_{\mu}$/ LHCb Collaboration The Cabibbo-suppressed semileptonic decay$B^{+}\to p\overline{p}\mu^{+}\nu_{\mu}$is observed for the first time using a sample of$pp$collisions corresponding to an integrated luminosity of 1.0, 2.0 and 1.7fb$^{-1}$at centre-of-mass energies of 7, 8 and 13TeV, respectively. The differential branching fraction is measured as a function of the$p\overline{p}$invariant mass using the decay mode$B^{+}\to J/\psi K^{+}$for normalisation. [...] arXiv:1911.08187; CERN-EP-2019-236; LHCB-PAPER-2019-034.- Geneva : CERN, 2020-03-25 - 22 p. - Published in : JHEP 2003 (2020) 146 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP; Supplementary information: ZIP; 2019-11-15 09:29  Determination of quantum numbers for several excited charmed mesons observed in$B^- \to D^{*+} \pi^- \pi^-$decays / LHCb Collaboration A four-body amplitude analysis of the$B^- \to D^{*+} \pi^- \pi^-$decay is performed, where fractions and relative phases of the various resonances contributing to the decay are measured. Several quasi-model-independent analyses are performed aimed at searching for the presence of new states and establishing the quantum numbers of previously observed charmed meson resonances. [...] arXiv:1911.05957; CERN-EP-2019-201; LHCb-PAPER-2019-027; LHCB-PAPER-2019-027.- Geneva : CERN, 2020-02-21 - 24 p. - Published in : Phys. Rev. D 101 (2020) 032005 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP; 2019-11-12 12:18  Measurement of the$\eta_c(1S)$production cross-section in$pp$collisions at$\sqrt{s} = 13$TeV / LHCb Collaboration Using a data sample corresponding to an integrated luminosity of$2.0\,fb^{-1}$, collected by the LHCb experiment, the production of the$\eta_c(1S)$state in proton-proton collisions at a centre-of-mass energy of$\sqrt{s}=13 \text{ TeV}$is studied in the rapidity range${2.0 < y < 4.5}$and in the transverse momentum range${6.5 < p_{T} < 14.0\text{ GeV}}$. The cross-section for prompt production of$\eta_c(1S)$mesons relative to that of the$J/\psi$meson is measured using the${p\bar{p}}$decay mode and is found to be${\sigma_{\eta_c(1S)}/\sigma_{J/\psi} = 1.69 \pm 0.15 \pm 0.10 \pm 0.18}$. [...] arXiv:1911.03326; LHCb-PAPER-2019-024; CERN-EP-2019-214; LHCB-PAPER-2019-024.- 2020-03-02 - 29 p. - Published in : Eur. Phys. J. C 80 (2020) 191 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP; Supplementary information: ZIP; 2019-11-04 11:32  Updated measurement of decay-time-dependent CP asymmetries in$D^0 \to K^+K^-$and$D^0 \to \pi^+\pi^-$decays / LHCb Collaboration A search for decay-time-dependent charge-parity ($CP$) asymmetry in$D^0 \to K^+K^-$and$D^0 \to \pi^+\pi^-$decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13TeV, and corresponding to an integrated luminosity of 5.4fb$^{-1}$. The$D^0$mesons are required to originate from semileptonic decays of$b$hadrons, such that the charge of the muon identifies the flavor of the neutral$D\$ meson at production. [...] arXiv:1911.01114; CERN-EP-2019-225; LHCb-PAPER-2019-032; LHCB-PAPER-2019-032.- Geneva : CERN, 2020-01-14 - 12 p. - Published in : Phys. Rev. D 101 (2020) 012005 Article from SCOAP3: PDF; Figures: ZIP; Fulltext: LHCb-PAPER-2019-032 - PDF; 1911.01114 - PDF; Supplementary information: ZIP; External link: Figures