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Register a new userConstraints on the unitarity triangle angle $gamma$ from Dalitz plot analysis of $B^0 to D K^+ pi^-$ decays
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The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of $B^0 to D K^+ pi^-$ decays, with $D to K^+ pi^-$, $K^+ K^-$ and $pi^+ pi^-$. The analysis is based on a data sample corresponding to $3.0,{rm fb}^{-1}$ of $pp$ collisions collected with the LHCb detector. No significant CP violation effect is seen, and constraints are placed on the angle $gamma$ of the unitarity triangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the $B^0 to D K^*(892)^0$ decay are determined for the first time. These measurements can be used to improve the sensitivity to $gamma$ of existing and future studies of the $B^0 to D K^*(892)^0$ decay.
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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.
The resonant substructure of $B_s^0 rightarrow bar{D}^0 K^- pi^+$ decays is studied with the Dalitz plot analysis technique. The study is based on a data sample corresponding to an integrated luminosity of $3.0,{rm fb}^{-1}$ of $pp$ collision data recorded by LHCb. A structure at $m(bar{D}^0 K^-) approx 2.86 {rm GeV}/c^2$ is found to be an admixture of spin-1 and spin-3 resonances. The masses and widths of these states and of the $D^*_{s2}(2573)^-$ meson are measured, as are the complex amplitudes and fit fractions for all the $bar{D}^0 K^-$ and $K^-pi^+$ components included in the amplitude model. In addition, the $D^*_{s2}(2573)^-$ resonance is confirmed to be spin-2.
We perform an analysis of the $D^+ to K^0_S pi^+ pi^0$ Dalitz plot using a data set of 2.92 fb$^{-1}$ of $e^+e^-$ collisions at the $psi(3770)$ mass accumulated by the BESIII Experiment, in which 166694 candidate events are selected with a background of 15.1%. The Dalitz plot is found to be well-represented by a combination of six quasi-two-body decay channels ($K^0_Srho^+$, $K^0_Srho(1450)^+$, $overline{K}^{*0}pi^+$, $overline{K}_0(1430)^0pi^+$, $overline{K}(1680)^0pi^+$, $overline{kappa}^0pi^+$) plus a small non-resonant component. Using the fit fractions from this analysis, partial branching ratios are updated with higher precision than previous measurements.
A binned Dalitz plot analysis of $B^pm to D K^pm$ decays, with $D to K^0_{rm S} pi^+pi^-$ and $D to K^0_{rm S} K^+ K^-$, is performed to measure the CP-violating observables $x_{pm}$ and $y_{pm}$ which are sensitive to the CKM angle $gamma$. The analysis exploits 1.0 $rm fb^{-1}$ of data collected by the LHCb experiment. The study makes no model-based assumption on the variation of the strong phase of the D decay amplitude over the Dalitz plot, but uses measurements of this quantity from CLEO-c as input. The values of the parameters are found to be $x_- = (0.0 pm 4.3 pm 1.5 pm 0.6) times 10^{-2}$, $y_- = (2.7 pm 5.2 pm 0.8 pm 2.3) times 10^{-2}$, $x_+ = (-10.3 pm 4.5 pm 1.8 pm 1.4)times 10^{-2}$ and $y_+ = (-0.9 pm 3.7 pm 0.8 pm 3.0)times 10^{-2}$. The first, second, and third uncertainties are the statistical, the experimental systematic, and the error associated with the precision of the strong-phase parameters measured at CLEO-c, respectively. These results correspond to $gamma = (44^{,+43}_{,-38})^circ$, with a second solution at $gamma to gamma + 180^circ$, and $r_B = 0.07 pm 0.04$, where $r_B$ is the ratio between the suppressed and favoured B decay amplitudes.
We present first evidence that the cosine of the CP-violating weak phase $2beta$ is positive, and hence exclude trigonometric multifold solutions of the CKM Unitarity Triangle using a time-dependent Dalitz plot analysis of $B^{0} to D^{(*)} h^{0}$ with $D to K_{S}^{0} pi^{+} pi^{-}$ decays, where $h^{0} in {pi^{0}, eta, omega }$ denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BaBar and Belle experiments collected at the $Upsilon(4S)$ resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain $( 471 pm 3 )times 10^6, Bbar{B}$ pairs recorded by the BaBar detector and $( 772 pm 11 )times 10^6, Bbar{B}$ pairs recorded by the Belle detector. The results of the measurement are $sin{2beta} = 0.80 pm 0.14 ,(rm{stat.}) pm 0.06 ,(rm{syst.}) pm 0.03 ,(rm{model})$ and $cos{2beta} = 0.91 pm 0.22 ,(rm{stat.}) pm 0.09 ,(rm{syst.}) pm 0.07 ,(rm{model})$. The result for the direct measurement of the angle $beta$ of the CKM Unitarity Triangle is $beta = left( 22.5 pm 4.4 ,(rm{stat.}) pm 1.2 ,(rm{syst.}) pm 0.6 ,(rm{model}) right)^{circ}$. The quoted model uncertainties are due to the composition of the $D^{0} to K_{S}^{0} pi^{+} pi^{-}$ decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics $e^{+}e^{-} to cbar{c}$ data sample. CP violation is observed in $B^{0} to D^{(*)} h^{0}$ decays at the level of $5.1$ standard deviations. The significance for $cos{2beta}>0$ is $3.7$ standard deviations. The trigonometric multifold solution $pi/2 - beta = (68.1 pm 0.7)^{circ}$ is excluded at the level of $7.3$ standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.
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