# EP Articles

Nyeste elementer:
2022-02-21
17:10
 Measurement of the charm mixing parameter $y_{CP} - y_{CP}^{K\pi}$ using two-body $D^0$ meson decays / LHCb Collaboration A measurement of the ratios of the effective decay widths of $D^0 \to \pi^-\pi^+$ and $D^0 \to K^-K^+$ decays over that of $D^0 \to K^-\pi^+$ decays is performed with the LHCb experiment using proton-proton collisions at a centre-of-mass energy of $13\,\mathrm{TeV}$, corresponding to an integrated luminosity of $6\,\mathrm{fb^{-1}}$. These observables give access to the charm mixing parameters $y_{CP}^{\pi\pi} - y_{CP}^{K\pi}$ and $y_{CP}^{KK} - y_{CP}^{K\pi}$, and are measured as $y_{CP}^{\pi\pi} - y_{CP}^{K\pi} = (6.57 \pm 0.53 \pm 0.16) \times 10^{-3}$, $y_{CP}^{KK} - y_{CP}^{K\pi} = (7.08 \pm 0.30 \pm 0.14) \times 10^{-3}$, where the first uncertainties are statistical and the second systematic. [...] arXiv:2202.09106; LHCb-PAPER-2021-041; CERN-EP-2022-022; LHCB-PAPER-2021-041.- 2022-05-01 - 27 p. - Published in : Phys. Rev. D 105 (2022) 092013 Fulltext: PhysRevD.105.092013 - PDF; 2202.09106 - PDF; LHCb-PAPER-2021-041 - PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2022-02-18
14:54
 Observation of the doubly charmed baryon decay ${\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+}$ / LHCb Collaboration The $\it{\Xi_{cc}^{++}\to \Xi_{c}^{'+}\pi^{+}}$ decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of $13\mathrm{\,Te\kern -0.1em V}$, corresponding to an integrated luminosity of $5.4\,\mathrm{fb}^{-1}$. The $\it{\Xi_{cc}^{++}\to \Xi_{c}^{'+}\pi^{+}}$ decay is reconstructed partially, where the photon from the $\it{\Xi_{c}^{'+} \to \Xi_{c}^{+}\gamma}$ decay is not reconstructed and the $pK^-\pi^+$ final state of the $\it{\Xi_{c}^{+}}$ baryon is employed. [...] arXiv:2202.05648; LHCb-PAPER-2021-052; CERN-EP-2022-016.- 2022-05-06 - 19 p. - Published in : JHEP 2205 (2022) 038 Fulltext: LHCb-PAPER-2021-052_to_arXiv_ - PDF; document - PDF; 2202.05648 - PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2022-02-10
15:35
 Study of charmonium and charmonium-like contributions in $B^+ \rightarrow J/\psi \eta K^+$ decays / LHCb Collaboration A study of $B^+ \rightarrow J/\psi \eta K^+$ decays, followed by $J/\psi \rightarrow \mu^+ \mu^-$ and $\eta \rightarrow \gamma \gamma$, is performed using a dataset collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb$^{-1}$. The $J/\psi\eta$ mass spectrum is investigated for contributions from charmonia and charmonium-like states. [...] arXiv:2202.04045; CERN-EP-2022-009; LHCb-PAPER-2021-047; LHCB-PAPER-2021-047.- Geneva : CERN, 2022 - 31 p. - Published in : JHEP 2022 (2020) 046 Fulltext: PDF; Related data file(s): LHCb-PAPER-2021-047-figures - ZIP; LHCb-PAPER-2021-047 - PDF;

2022-01-10
15:35
 Observation of the decay $\Lambda_b^0\rightarrow \Lambda_c^+\tau^-\overline{\nu}_{\tau}$ / LHCb Collaboration The first observation of the semileptonic $b$-baryon decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \tau^-\overline{\nu}_{\tau}$, with a significance of $6.1\,\sigma$, is reported using a data sample corresponding to 3 fb$^{-1}$ of integrated luminosity, collected by the LHCb experiment at centre-of-mass energies of 7 and 8~TeV at the LHC. The $\tau^-$ lepton is reconstructed in the hadronic decay to three charged pions. [...] arXiv:2201.03497; LHCb-PAPER-2021-044; CERN-EP-2021-265; LHCB-PAPER-2021-044.- Geneva : CERN, 2022-05-13 - 21 p. - Published in : Phys. Rev. Lett. 128 (2022) 191803 Fulltext: 2201.03497 - PDF; PhysRevLett.128.191803 - PDF; Related data file(s): ZIP; Supplementary material: ZIP;

2022-01-07
13:56
 Observation of the $B^0\rightarrow\overline{D}^{*0}K^{+}\pi^{-}$ and $B_s^0\rightarrow\overline{D}^{*0}K^{-}\pi^{+}$ decays / LHCb Collaboration The first observations of $B^0\rightarrow\overline{D}^{*}(2007)^{0}K^{+}\pi^{-}$ and $B_s^0\rightarrow\overline{D}^{*}(2007)^{0}K^{-}\pi^{+}$ decays are presented, and their branching fractions relative to that of the $B^0\rightarrow\overline{D}^{*}(2007)^{0}\pi^{+}\pi^{-}$ decay are reported. These modes can potentially be used to investigate the spectroscopy of charm and charm-strange resonances and to determine the angle $\gamma$ of the CKM unitarity triangle. [...] arXiv:2112.11428; LHCb-PAPER-2021-043; CERN-EP-2021-262; LHCB-PAPER-2021-043.- Geneva : CERN, 2022-04-01 - 32 p. - Published in : Phys. Rev. D 105 (2022) 072005 Fulltext: LHCb-PAPER-2021-043 - PDF; 2112.11428 - PDF; Publication - PDF; Related data file(s): ZIP;

2021-12-06
12:17
 Observation of $\Lambda_b^0\rightarrow D^+ p \pi^-\pi^-$ and $\Lambda_b^0\rightarrow D^{*+} p \pi^-\pi^-$ decays / LHCb Collaboration The multihadron decays $\Lambda_b^0\rightarrow D^+ p \pi^-\pi^-$ and $\Lambda_b^0\rightarrow D^{*+} p \pi^-\pi^-$ are observed in data corresponding to an integrated luminosity of 3fb$^{-1}$, collected in proton-proton collisions at centre-of-mass energies of 7 and 8TeV by the LHCb detector. Using the decay $\Lambda_b^0\rightarrow \Lambda_c^+ \pi^+ \pi^-\pi^-$ as a normalisation channel, the ratio of branching fractions is measured to be arXiv:2112.02013; LHCb-PAPER-2021-040; CERN-EP-2021-237; LHCB-PAPER-2021-040.- Geneva : CERN, 2022-03-23 - 30 p. - Published in : JHEP 2203 (2022) 153 Fulltext: document - PDF; 2112.02013 - PDF; Related data file(s): ZIP;

2021-11-23
12:08
 Measurement of the photon polarization in $\Lambda_{b}^{0}$ $\to$ $\Lambda$ $\gamma$ decays / LHCb Collaboration The photon polarization in $b\to s\gamma$ transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of $\Lambda_{b}^{0}\to\Lambda\gamma$ decays. A data sample corresponding to an integrated luminosity of $6\;\mathrm{fb^{-1}}$ collected by the LHCb experiment in $pp$ collisions at a center-of-mass energy of $13\;\mathrm{TeV}$ is used. [...] arXiv:2111.10194; LHCb-PAPER-2021-030; CERN-EP-2021-230.- 2022-03-01 - 11 p. - Published in : Phys. Rev. D 105 (2022) L051104 Fulltext: 2111.10194 - PDF; Lb2L0Gamma_Angular_Paper - PDF; Related data file(s): ZIP; Supplementary information: ZIP;

2021-11-23
11:49
 Searches for rare ${B}_s^0$ and B$^{0}$ decays into four muons / LHCb Collaboration Searches for rare $B_s^0$ and $B^0$ decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 $\text{fb}^{-1}$. Direct decays and decays via light scalar and $J/\psi$ resonances are considered. [...] arXiv:2111.11339; LHCb-PAPER-2021-039; CERN-EP-2021-236.- 2022-03-17 - 27 p. - Published in : JHEP 2203 (2022) 109 Fulltext: 2111.11339 - PDF; document - PDF; Fulltext from publisher: PDF; Related data file(s): ZIP;

2021-11-08
11:29
 Study of ${\mathrm{B}}_{\mathrm{c}}^{+}$ decays to charmonia and three light hadrons / LHCb Collaboration Using proton-proton collision data, corresponding to an integrated luminosity of $9fb^{-1}$ collected with the LHCb detector, seven decay modes of the $B_c^+$ meson into a $J/\psi$ or $\psi(2S)$ meson and three charged hadrons, kaons or pions, are studied. The decays $B_c^+\rightarrow ( \psi(2S) \rightarrow J/\psi \pi^+ \pi^-)\pi^+$, $B_c^+\rightarrow \psi(2S)\pi^+\pi^+\pi^-$, $B_c^+\rightarrow J/\psi K^+\pi^+\pi^-$ and $B_c^+\rightarrow J/\psi K^+K^+K^-$ are observed for the first time, and evidence for the $B_c^+\rightarrow \psi(2S)K^+K^-\pi^+$ decay is found, where $J/\psi$ and $\psi(2S)$ mesons are reconstructed in their dimuon decay modes. [...] arXiv:2111.03001; LHCb-PAPER-2021-034; CERN-EP-2021-216; LHCB-PAPER-2021-034.- Geneva : CERN, 2022-01-13 - 29 p. - Published in : JHEP 2201 (2022) 065 Fulltext: document - PDF; 2111.03001 - PDF; Related data file(s): ZIP;

2021-11-08
11:14
 Angular Analysis of $D^0 \to \pi^+\pi^-\mu^+\mu^-$ and $D^0 \to K^+K^-\mu^+\mu^-$ Decays and Search for $CP$ Violation / LHCb Collaboration The first full angular analysis and an updated measurement of the decay-rate $CP$ asymmetry of the $D^0 \to \pi^+\pi^-\mu^+\mu^-$ and $D^0 \to K^+K^-\mu^+\mu^-$ decays are reported. The analysis uses proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. [...] arXiv:2111.03327; LHCb-PAPER-2021-035; CERN-EP-2021-212.- 2022-06-03 - 11 p. - Published in : Phys. Rev. Lett. 128 (2022) 221801 Fulltext: PDF; Related data file(s): ZIP; Supplementary information: ZIP;