173 research outputs found

    Observation of Two New Excited Ξb0 States Decaying to Λb0 K-π+

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    Two narrow resonant states are observed in the Λb0K-π+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Λb0K-π+ system indicates that these are excited Ξb0 baryons. The masses of the Ξb(6327)0 and Ξb(6333)0 states are m[Ξb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Ξb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Δm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Λb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Γ[Ξb(6327)0]<2.20(2.56) and Γ[Ξb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Ξb0 resonances

    Measurement of D s <sup>±</sup> production asymmetry in pp collisions at √s=7 and 8 TeV

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    The inclusive Ds±D_s^{\pm} production asymmetry is measured in pppp collisions collected by the LHCb experiment at centre-of-mass energies of s=7\sqrt{s} =7 and 8 TeV. Promptly produced Ds±D_s^{\pm} mesons are used, which decay as Ds±→ϕπ±D_s^{\pm}\to\phi\pi^{\pm}, with ϕ→K+K−\phi\to K^+K^-. The measurement is performed in bins of transverse momentum, pTp_{\rm T}, and rapidity, yy, covering the range 2.5<pT<25.02.5<p_{\rm T}<25.0 GeV/c/c and 2.0<y<4.52.0<y<4.5. No kinematic dependence is observed. Evidence of nonzero Ds±D_s^{\pm} production asymmetry is found with a significance of 3.3 standard deviations.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2018-010.htm

    Search for CP violation in Λb0→pK− and Λb0→pπ− decays

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    A search for CP violation in Λb0→pK− and Λb0→pπ− decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0fb−1. The CP -violating asymmetries are measured to be ACPpK−=−0.020±0.013±0.019 and ACPpπ−=−0.035±0.017±0.020, and their difference ACPpK−−ACPpπ−=0.014±0.022±0.010, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date

    Observation and branching fraction measurement of the decay Ξb- → Λ0 bπ -

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    Precision measurement of CP\it{CP} violation in the penguin-mediated decay Bs0→ϕϕB_s^{0}\rightarrow\phi\phi

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    A flavor-tagged time-dependent angular analysis of the decay Bs0→ϕϕB_s^{0}\rightarrow\phi\phi is performed using pppp collision data collected by the LHCb experiment at % at s=13\sqrt{s}=13 TeV, the center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The CP\it{CP}-violating phase and direct CP\it{CP}-violation parameter are measured to be ϕssˉs=−0.042±0.075±0.009\phi_{s\bar{s}s} = -0.042 \pm 0.075 \pm 0.009 rad and ∣λ∣=1.004±0.030±0.009|\lambda|=1.004\pm 0.030 \pm 0.009 , respectively, assuming the same values for all polarization states of the ϕϕ\phi\phi system. In these results, the first uncertainties are statistical and the second systematic. These parameters are also determined separately for each polarization state, showing no evidence for polarization dependence. The results are combined with previous LHCb measurements using pppp collisions at center-of-mass energies of 7 and 8 TeV, yielding ϕssˉs=−0.074±0.069\phi_{s\bar{s}s} = -0.074 \pm 0.069 rad and ∣lambda∣=1.009±0.030|lambda|=1.009 \pm 0.030. This is the most precise study of time-dependent CP\it{CP} violation in a penguin-dominated BB meson decay. The results are consistent with CP\it{CP} symmetry and with the Standard Model predictions.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-001.html (LHCb public pages

    Measurement of the Λb0→Λ(1520)ÎŒ+Ό−\Lambda_{b}^{0}\to \Lambda(1520) \mu^{+}\mu^{-} differential branching fraction

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    The branching fraction of the rare decay Λb0→Λ(1520)ÎŒ+Ό−\Lambda_{b}^{0}\to \Lambda(1520) \mu^{+}\mu^{-} is measured for the first time, in the squared dimuon mass intervals, q2q^2, excluding the J/ψJ/\psi and ψ(2S)\psi(2S) regions. The data sample analyzed was collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of $9\ \mathrm{fb}^{-1}.Theresultinthehighest. The result in the highest q^{2}interval, interval, q^{2} >15.0\ \mathrm{GeV}^2/c^4$, where theoretical predictions have the smallest model dependence, agrees with the predictions.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-050.html (LHCb public pages

    Rare variants of large effect in BRCA2 and CHEK2 affect risk of lung cancer.

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    We conducted imputation to the 1000 Genomes Project of four genome-wide association studies of lung cancer in populations of European ancestry (11,348 cases and 15,861 controls) and genotyped an additional 10,246 cases and 38,295 controls for follow-up. We identified large-effect genome-wide associations for squamous lung cancer with the rare variants BRCA2 p.Lys3326X (rs11571833, odds ratio (OR) = 2.47, P = 4.74 × 10(-20)) and CHEK2 p.Ile157Thr (rs17879961, OR = 0.38, P = 1.27 × 10(-13)). We also showed an association between common variation at 3q28 (TP63, rs13314271, OR = 1.13, P = 7.22 × 10(-10)) and lung adenocarcinoma that had been previously reported only in Asians. These findings provide further evidence for inherited genetic susceptibility to lung cancer and its biological basis. Additionally, our analysis demonstrates that imputation can identify rare disease-causing variants with substantive effects on cancer risk from preexisting genome-wide association study data

    Search for dark photons produced in 13 TeV pppp collisions

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    Searches are performed for both promptlike and long-lived dark photons, A 0 , produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using A 0 → ÎŒ ĂŸ ÎŒ − decays and a data sample corresponding to an integrated luminosity of 1 . 6 fb − 1 collected with the LHCb detector. The promptlike A 0 search covers the mass range from near the dimuon threshold up to 70 GeV, while the long-lived A 0 search is restricted to the low-mass region 214 <m Ă° A 0 Þ < 350 MeV. No evidence for a signal is found, and 90% confidence level exclusion limits are placed on the Îł – A 0 kinetic-mixing strength. The constraints placed on promptlike dark photons are the most stringent to date for the mass range 10 . 6 <m Ă° A 0 Þ < 70 GeV, and are comparable to the best existing limits for m Ă° A 0 Þ < 0 . 5 GeV. The search for long-lived dark photons is the first to achieve sensitivity using a displaced-vertex signature

    Measurement of CPCP asymmetry in Bs0→Ds∓K±B_s^0 \to D_s^{\mp} K^{\pm} decays

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    We report the measurements of the CPCP-violating parameters in Bs0→Ds∓K±B_s^0 \to D_s^{\mp} K^{\pm} decays observed in pppp collisions, using a data set corresponding to an integrated luminosity of 3.0 fb−13.0\,\text{fb}^{-1} recorded with the LHCb detector. We measure Cf=0.73±0.14±0.05C_f = 0.73 \pm 0.14 \pm 0.05, AfΔΓ=0.39±0.28±0.15A^{\Delta \Gamma}_f = 0.39 \pm 0.28 \pm 0.15, Af‟ΔΓ=0.31±0.28±0.15A^{\Delta \Gamma}_{\overline{f}} = 0.31 \pm 0.28 \pm 0.15, Sf=−0.52±0.20±0.07S_f = -0.52 \pm 0.20 \pm 0.07, Sf‟=−0.49±0.20±0.07S_{\overline{f}} = -0.49 \pm 0.20 \pm 0.07, where the uncertainties are statistical and systematic, respectively. These parameters are used together with the world-average value of the Bs0B_s^0 mixing phase, −2ÎČs-2\beta_s, to obtain a measurement of the CKM angle Îł\gamma from Bs0→Ds∓K±B_s^0 \to D_s^{\mp} K^{\pm} decays, yielding \gamma = (128\,_{-22}^{+17})^\circ modulo 180∘180^\circ, where the uncertainty contains both statistical and systematic contributions. This corresponds to 3.8 σ3.8\,\sigma evidence for CPCP violation in the interference between decay and decay after mixing.We report the measurements of the CP -violating parameters in Bs0_{s}^{0}  → Ds∓_{s}^{∓} K±^{±} decays observed in pp collisions, using a data set corresponding to an integrated luminosity of 3.0 fb−1^{−1} recorded with the LHCb detector. We measure Cf_{f} = 0.73 ± 0.14 ± 0.05, AfΔΓ_{f}^{ΔΓ}  = 0.39 ± 0.28 ± 0.15, Af‟ΔΓ=0.31±0.28±0.15 {A}_{\overline{f}}^{\varDelta \varGamma }=0.31\pm 0.28\pm 0.15 , Sf_{f} = −0.52 ± 0.20 ± 0.07, Sf‟=−0.49±0.20±0.07 {S}_{\overline{f}}=-0.49\pm 0.20\pm 0.07 , where the uncertainties are statistical and systematic, respectively. These parameters are used together with the world-average value of the Bs0_{s}^{0} mixing phase, −2ÎČs_{s} , to obtain a measurement of the CKM angle Îł from Bs0_{s}^{0}  → Ds∓_{s}^{∓} K±^{±} decays, yielding γ = (128− 22+ 17_{− 22}^{+ 17} )° modulo 180°, where the uncertainty contains both statistical and systematic contributions. This corresponds to 3.8 σ evidence for CP violation in the interference between decay and decay after mixing
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