18 research outputs found

    Measurement of the CKM angle γγ in B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm \to D π^\pm decays with D→KS0h+h−D \to K_\mathrm S^0 h^+ h^-

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    A measurement of CPCP-violating observables is performed using the decays B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm\to D \pi^\pm, where the DD meson is reconstructed in one of the self-conjugate three-body final states KSπ+π−K_{\mathrm S}\pi^+\pi^- and KSK+K−K_{\mathrm S}K^+K^- (commonly denoted KSh+h−K_{\mathrm S} h^+h^-). The decays are analysed in bins of the DD-decay phase space, leading to a measurement that is independent of the modelling of the DD-decay amplitude. The observables are interpreted in terms of the CKM angle Îł\gamma. Using a data sample corresponding to an integrated luminosity of 9 fb−19\,\text{fb}^{-1} collected in proton-proton collisions at centre-of-mass energies of 77, 88, and 13 TeV13\,\text{TeV} with the LHCb experiment, Îł\gamma is measured to be (68.7−5.1+5.2)∘\left(68.7^{+5.2}_{-5.1}\right)^\circ. The hadronic parameters rBDKr_B^{DK}, rBDπr_B^{D\pi}, ÎŽBDK\delta_B^{DK}, and ÎŽBDπ\delta_B^{D\pi}, which are the ratios and strong-phase differences of the suppressed and favoured B±B^\pm decays, are also reported

    Study of the lineshape of the chi(c1) (3872) state

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    A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations

    Measurement of the branching fraction of the B0→Ds+π−{{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} decay

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    International audienceA branching fraction measurement of the B0→Ds+π−{{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of 5.0 fb−15.0\,\text {fb} ^{-1} . The branching fraction is found to be B(B0→Ds+π−)=(19.4±1.8±1.3±1.2)×10−6{\mathcal {B}} ({{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} ) =(19.4 \pm 1.8\pm 1.3 \pm 1.2)\times 10^{-6}, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the B0→D−π+{{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} , Ds+→K+K−π+{{D} ^+_{s}} {\rightarrow }{{K} ^+} {{K} ^-} {{\pi } ^+} and D−→K+π−π−{{D} ^-} {\rightarrow }{{K} ^+} {{\pi } ^-} {{\pi } ^-} branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a b→ub{\rightarrow }u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element VubV_{ub}. Additionally, the collision energy dependence of the hadronisation-fraction ratio fs/fdf_s/f_d is measured through B‟s0→Ds+π−{{\overline{B}} {}^0_{s}} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} and B0→D−π+{{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} decays
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