# EP Articles

2019-04-10
11:16
 Observation of a narrow pentaquark state, $P_c(4312)^+$, and of two-peak structure of the $P_c(4450)^+$ / LHCb Collaboration A narrow pentaquark state, $P_c(4312)^+$, decaying to $J/\psi p$ is discovered with a statistical significance of $7.3\sigma$ in a data sample of $\Lambda_b^0\to J/\psi p K^-$ decays which is an order of magnitude larger than that previously analyzed by the LHCb collaboration. The $P_c(4450)^+$ pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, $P_c(4440)^+$ and $P_c(4457)^+$, where the statistical significance of this two-peak interpretation is $5.4\sigma$. [...] arXiv:1904.03947; LHCb-PAPER-2019-014 CERN-EP-2019-058; LHCB-PAPER-2019-014.- Geneva : CERN, 2019-06-06 - 11 p. - Published in : Phys. Rev. Lett. 122 (2019) 222001 Fulltext: PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP; External link: SYMMETRY

2019-04-01
11:42
 Observation of an excited $B_c^+$ state / LHCb Collaboration Using $pp$ collision data corresponding to an integrated luminosity of $8.5\,\mathrm{fb}^{-1}$ recorded by the LHCb experiment at centre-of-mass energies of $\sqrt{s} = 7$, $8$ and $13\mathrm{\,Te\kern -0.1em V}$, the observation of an excited $B_c^+$ state in the $B_c^+\pi^+\pi^-$ invariant-mass spectrum is reported. The state has a mass of $6841.2 \pm 0.6 {\,\rm (stat)\,} \pm 0.1 {\,\rm (syst)\,} \pm 0.8\,(B_c^+) \mathrm{\,MeV}/c^2$, where the last uncertainty is due to the limited knowledge of the $B_c^+$ mass. [...] arXiv:1904.00081; CERN-EP-2019-050; LHCb-PAPER-2019-007.- Geneva : CERN, 2019-06-11 - 10 p. - Published in : Phys. Rev. Lett. 122 (2019) 232001 Fulltext: PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-03-22
09:21
 Search for lepton-universality violation in $B^+\to K^+\ell^+\ell^-$ decays / LHCb Collaboration A measurement of the ratio of branching fractions of the decays $B^+\to K^+\mu^+\mu^-$ and $B^+\to K^+e^+e^-$ is presented. The proton-proton collision data used correspond to an integrated luminosity of $5.0$ fb$^{-1}$ recorded with the LHCb experiment at centre-of-mass energies of $7$, $8$ and $13$ TeV. [...] arXiv:1903.09252; LHCb-PAPER-2019-009; CERN-EP-2019-043; LHCb-PAPER-2019-009 CERN-EP-2019-043.- Geneva : CERN, 2019-05-14 - 13 p. - Published in : Phys. Rev. Lett. 122 (2019) 191801 Fulltext: 1903.09252 - PDF; LHCb-PAPER-2019-009 - PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-03-21
08:49
 Observation of $C\!P$ violation in charm decays / LHCb Collaboration A search for charge-parity ($C\!P$) violation in $D^0 \to K^- K^+$ and $D^0 \to \pi^- \pi^+$ decays is reported, using $pp$ collision data corresponding to an integrated luminosity of 6 $\mathrm{fb}^{-1}$ collected at a center-of-mass energy of 13 TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in $D^*(2010)^+ \to D^0 \pi^+$ decays or from the charge of the muon in $\overline{B} \to D^0 \mu^-\bar{\nu}_\mu X$ decays. [...] arXiv:1903.08726; LHCb-PAPER-2019-006; CERN-EP-2019-042; LHCB-PAPER-2019-006.- Geneva : CERN, 2019-05-29 - 12 p. - Published in : Phys. Rev. Lett. 122 (2019) 211803 Fulltext: LHCb-PAPER-2019-006 - PDF; 1903.08726 - PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP; External link: SYMMETRY

2019-03-08
09:57
 Measurement of the mass difference between neutral charm-meson eigenstates / LHCb Collaboration We report a measurement of the mass difference between neutral charm-meson eigenstates using a novel approach that enhances sensitivity to this parameter. We use $2.3\times10^6$ $D^0\to K_S^0\pi^+\pi^-$ decays reconstructed in proton-proton collisions collected by the LHCb experiment in 2011 and 2012. [...] arXiv:1903.03074; CERN-EP-2019-032; LHCb-PAPER-2019-001.- Geneva : CERN, 2019-06-14 - 10 p. - Published in : Phys. Rev. Lett. 122 (2019) 231802 Fulltext: PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-03-05
09:57
 Search for $CP$ violation in $D^+_s\to K_S^0\pi^+$, $D^+\to K_S^0K^+$ and $D^+\to\phi\pi^+$ decays / LHCb Collaboration A search for charge-parity ($CP$) violation in Cabibbo-suppressed $D^+_s\to K_S^0\pi^+$, $D^+\to K_S^0K^+$ and $D^+\to\phi\pi^+$ decays is reported using proton-proton collision data, corresponding to an integrated luminosity of 3.8 fb$^{-1}$, collected at a center-of-mass energy of 13 TeV with the LHCb detector. High-yield samples of kinematically and topologically similar Cabibbo-favored $D_{(s)}^+$ decays are analyzed to subtract nuisance asymmetries due to production and detection effects, including those induced by $CP$ violation in the neutral kaon system. [...] arXiv:1903.01150; LHCb-PAPER-2019-002; CERN-EP-2019-027.- Geneva : CERN, 2019-05-17 - 11 p. - Published in : Phys. Rev. Lett. 122 (2019) 191803 Fulltext: PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-02-18
13:51
 Dalitz Plot analysis of the $D^+ \to K^- K^+ K^+$ decay / LHCb Collaboration The resonant structure of the doubly Cabibbo-suppressed decay $D^+\to K^-K^+K^+$ is studied for the first time. The measurement is based on a sample of $pp$-collision data, collected at a centre-of-mass energy of 8 TeV with the LHCb detector and corresponding to an integrated luminosity of 2 fb$^-1$. [...] arXiv:1902.05884; LHCb-PAPER-2018-039; CERN-EP-2018-336.- Geneva : CERN, 2019-04-08 - 37 p. - Published in : JHEP 04 (2019) 063 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP;

2019-02-15
15:26
 Observation of $B^0_{(s)} \to J/\psi p \overline{p}$ decays and precision measurements of the $B^0_{(s)}$ masses / LHCb Collaboration The first observation of the decays $B^0_{(s)} \to J/\psi p \overline{p}$ is reported, using proton-proton collision data corresponding to an integrated luminosity of $5.2{\text{fb}}^{-1}$, collected with the LHCb detector. These decays are suppressed due to limited available phase space, as well as due to OZI or Cabibbo suppression. [...] arXiv:1902.05588; CERN-EP-2019-006; LHCb-PAPER-2018-046.- Geneva : CERN, 2019-05-17 - 10 p. - Published in : Phys. Rev. Lett. 122 (2019) 191804 Fulltext: PDF; Fulltext from Publisher: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2019-02-15
10:02
 Measurement of $B^+$, $B^0$ and $\Lambda_b^0$ production in $p\mkern 1mu\mathrm{Pb}$ collisions at $\sqrt{s_{NN}} = 8.16 \ \rm TeV$ / LHCb Collaboration The production of $B^+$, $B^0$ and $\Lambda_b^0$ hadrons is studied in proton-lead collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}}=8.16\,{\rm TeV}$ recorded with the LHCb detector at the LHC. The measurement uses a dataset corresponding to an integrated luminosity of $12.2\pm0.3\ \mathrm{nb}^{-1}$ for the case where the proton beam is projected into the LHCb detector (corresponding to measuring hadron production at positive rapidity) and $18.6\pm0.5\ \mathrm{nb}^{-1}$ for the lead beam projected into the LHCb detector (corresponding to measuring hadron production at negative rapidity). [...] arXiv:1902.05599; LHCb-PAPER-2018-048; CERN-EP-2019-010; LHCb-PAPER-2018-048; CERN-EP-2019-010.- Geneva : CERN, 2019-03-28 - 21 p. - Published in : Phys. Rev. D 99 (2019) 052011 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP;

2019-02-07
15:59
 Measurement of the ratio of branching fractions of the decays $\Lambda_b^0 \!\to \psi(2S) \Lambda$ and $\Lambda_b^0 \!\to J\!/\!\psi \Lambda$ / LHCb Collaboration Using $pp$ collisions corresponding to 3$\,\text{fb}^{-1}$ integrated luminosity, recorded by the LHCb experiment at centre-of-mass energies of 7 and 8$\,\text{TeV}$, the ratio of branching fractions \begin{align*} \mathcal{B}(\Lambda^0_b\!\to\psi(2S) \Lambda )/\mathcal{B}(\Lambda^0_b\!\to J/\psi \Lambda)= 0.513 \pm 0.023\, (\text{stat}) \pm 0.016 \, (\text{syst}) \pm 0.011\, (\mathcal{B}) \end{align*} is determined. The first uncertainty is statistical, the second is systematic and the third is due to the external branching fractions used.. arXiv:1902.02092; LHCb-PAPER-2017-041; CERN-EP-2019-003.- Geneva : CERN, 2019-03-22 - 16 p. - Published in : JHEP 03 (2019) 126 Article from SCOAP3: PDF; Fulltext: PDF; Related data file(s): ZIP;