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Register a new userAmplitude analysis of the decay $overline{B}^0 to K_{S}^0 pi^+ pi^-$ and first observation of the CP asymmetry in $overline{B}^0 to K^{*}(892)^- pi^+$
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The time-integrated Dalitz plot of the three-body hadronic charmless decay ${{overline{B}}^0 to K_{mathrm{scriptscriptstyle S}}^0 pi^+ pi^-}$ is studied using a $pp$ collision data sample recorded with the LHCb detector, corresponding to an integrated luminosity of $3.0;mathrm{fb}^{-1}$. The decay amplitude is described with an isobar model. Relative contributions of the isobar amplitudes to the ${overline{B}^0 to K_{mathrm{scriptscriptstyle S}}^0 pi^+ pi^-}$ decay branching fraction and CP asymmetries of the flavour-specific amplitudes are measured. The CP asymmetry between the conjugate ${overline{B}^0 to K^{*}(892)^{-}pi^+}$ and ${overline{B}^0 to K^{*}(892)^{+}pi^-}$ decay rates is determined to be $-0.308 pm 0.062$.
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The first observation of the decay $B^0 rightarrow D^0 overline{D}{}^0 K^+ pi^-$ is reported using proton-proton collision data corresponding to an integrated luminosity of 4.7 $mathrm{fb}^{-1}$ collected by the LHCb experiment in 2011, 2012 and 2016. The measurement is performed in the full kinematically allowed range of the decay outside of the $D^{*-}$ region. The ratio of the branching fraction relative to that of the control channel $B^0 rightarrow D^{*-} D^0 K^+$ is measured to be $mathcal{R} = (14.2 pm 1.1 pm 1.0)%$, where the first uncertainty is statistical and the second is systematic. The absolute branching fraction of $B^0 rightarrow D^0 overline{D}{}^0 K^+ pi^-$ decays is thus determined to be $mathcal{B}(B^0 rightarrow D^0 overline{D}{}^0 K^+ pi^-) = (3.50 pm 0.27 pm 0.26 pm 0.30) times 10^{-4}$, where the third uncertainty is due to the branching fraction of the control channel. This decay mode is expected to provide insights to spectroscopy and the charm-loop contributions in rare semileptonic decays.
Proton-proton collision data recorded in 2011 and 2012 by the lhcb experiment, co-rres-pon-ding to an integrated luminosity of 3.0invfb, are a-na-lysed to search for the charmless ${B^0 to rho^0 rho^0}$ decay. More than 600 ${B^0 to (pi^+pi^-)(pi^+pi^-)}$ signal decays are selected and used to perform an amplitude analysis from which the ${B^0 to rho^0 rho^0}$ decay is observed for the first time with 7.1 standard deviations significance. The fraction of ${B^0 to rho^0 rho^0}$ decays yielding a longitudinally polarised final state is measured to be $fL = 0.745^{+0.048}_{-0.058} ({rm stat}) pm 0.034 ({rm syst})$. The ${B^0 to rho^0 rho^0}$ branching fraction, using the ${B^0 to phi K^*(892)^{0}}$ decay as reference, is also reported as ${BF(B^0 to rho^0 rho^0) = (0.94 pm 0.17 ({rm stat}) pm 0.09 ({rm syst}) pm 0.06 ({rm BF})) times 10^{-6}}$.
The resonant substructures of $B^0 to overline{D}^0 pi^+pi^-$ decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb$^{-1}$ of $pp$ collisions collected by the LHCb detector is used. The branching fraction of the $B^0 to overline{D}^0 pi^+pi^-$ decay in the region $m(overline{D}^0pi^{pm})>2.1$ GeV$/c^2$ is measured to be $(8.46 pm 0.14 pm 0.29 pm 0.40) times 10^{-4}$, where the first uncertainty is statistical, the second is systematic and the last arises from the normalisation channel $B^0 to D^*(2010)^-pi^+$. The $pi^+pi^-$ S-wave components are modelled with the Isobar and K-matrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at $m(overline{D}^0pi^-) approx 2.8$ GeV$/c^{2}$ is confirmed and its spin-parity is determined for the first time as $J^P = 3^-$. The branching fraction, mass and width of this structure are determined together with those of the $D^*_0(2400)^-$ and $D^*_2(2460)^-$ resonances. The branching fractions of other $B^0 to overline{D}^0 h^0$ decay components with $h^0 to pi^+pi^-$ are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays $B^0 to overline{D}^0 f_0(500)$, $B^0 to overline{D}^0 f_0(980)$, $B^0 to overline{D}^0 rho(1450)$, $B^0 to D_3^*(2760)^- pi^+$ and the first evidence of $B^0 to overline{D}^0 f_0(2020)$ are presented.
An amplitude analysis of ${B^0to (pi^+pi^-) (K^+pi^-)}$ decays is performed in the two-body invariant mass regions ${300 < m(pi^+pi^-)<1100}$ MeV/$c^2$, accounting for the $rho^0$, $omega$, $f_0(500)$, $f_0(980)$ and $f_0(1370)$ resonances, and ${750 < m(K^+pi^-)<1200}$ MeV/$c^2$, which is dominated by the $K^{*}(892)^0$ meson. The analysis uses 3 fb$^{-1}$ of proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The $CP$ averages and asymmetries are measured for the magnitudes and phase differences of the contributing amplitudes. The $CP$-averaged longitudinal polarisation fractions of the vector-vector modes are found to be $tilde{f}^0_{rho K^{*}} = 0.164 pm 0.015 pm 0.022$ and $tilde{f}^0_{omega K^{*}} = 0.68 pm 0.17 pm 0.16$, and their $CP$ asymmetries, $mathcal{A}^0_{rho K^{*}} = -0.62 pm 0.09 pm 0.09$ and $mathcal{A}^0_{omega K^{*}} = -0.13 pm 0.27 pm 0.13$, where the first uncertainty is statistical and the second systematic.
The decay $overline{B}_s^0 rightarrow psi(2S) K^+ pi^-$ is observed using a data set corresponding to an integrated luminosity of $3.0fb^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. The branching fraction relative to the $B^0rightarrow psi(2S) K^+ pi^-$ decay mode is measured to be begin{equation} frac{{cal B}(overline{B}^0_s rightarrow psi(2S) K^+ pi^-)}{{cal B}(B^0 rightarrow psi(2S) K^+ pi^-)} = 5.38 pm 0.36 (stat) pm 0.22 (syst) pm 0.31 , (f_s/f_d) , %, onumber end{equation} where $f_s/f_d$ indicates the uncertainty due to the ratio of probabilities for a $b$ quark to hadronise into a $B_s^0$ or $B^0$ meson. Using an amplitude analysis, the fraction of decays proceeding via an intermediate $K^*(892)^0$ meson is measured to be $0.645 pm 0.049 (stat) pm 0.049 (syst)$ and its longitudinal polarisation fraction is $0.524 pm 0.056 (stat) pm 0.029 (syst)$. The relative branching fraction for this component is determined to be begin{equation} frac{{cal B}(overline{B}^0_s rightarrow psi(2S) K^*(892)^0)}{{cal B}(B^0 rightarrow psi(2S) K^*(892)^0)} = 5.58 pm 0.57 (stat) pm 0.40 (syst) pm 0.32 , (f_s/f_d) , %. onumber end{equation} In addition, the mass splitting between the $B_s^0$ and $B^0$ mesons is measured as begin{equation} M(B^0_s) - M(B^0) = 87.45 pm 0.44 (stat) pm 0.07 (syst) MeV/c^2. onumber end{equation}
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