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Register a new userEvidence for the charmless annihilation decay mode $B^0_s to pi^+pi^-$
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CDF Collaboration
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We search for annihilation decay modes of neutral $b$ mesons into pairs of charmless charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 6 fb$^{-1}$ of integrated luminosity, we obtain the first evidence for the $B^0_s to pi^+pi^-$ decay, with a significance of $3.7sigma$, and a measured branching ratio $mathcal{B}(B^0_s to pi^+pi^-)= (0.57 pm 0.15 (stat) pm 0.10 (syst))times 10^{-6}$. A search for the $B^0 to K^+K^-$ mode in the same sample yields a significance of $2.0sigma$, and a central value estimate $mathcal{B}(B^0 to K^+K^-)= (0.23 pm 0.10 (stat) pm 0.10 (syst))times 10^{-6}$.
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The first observation of the rare decay$B^0_s to phipi^+pi^-$ and evidence for $B^0 to phipi^+pi^-$ are reported, using $pp$ collision data recorded by the LHCb detector at centre-of-mass energies $sqrt{s} = 7$ and 8~TeV, corresponding to an integrated luminosity of $3{mbox{,fb}^{-1}}$. The branching fractions in the $pi^+pi^-$ invariant mass range $400<m(pi^+pi^-)<1600{mathrm{,Mekern -0.1em V!/}c^2}$ are $[3.48pm 0.23pm 0.17pm 0.35]times 10^{-6}$ and $[1.82pm 0.25pm 0.41pm 0.14]times 10^{-7}$ for $B^0_s to phipi^+pi^-$ and $B^0 to phipi^+pi^-$ respectively, where the uncertainties are statistical, systematic and from the normalisation mode $B^0_s to phiphi $. A combined analysis of the $pi^+pi^-$ mass spectrum and the decay angles of the final-state particles identifies the exclusive decays $B^0_s to phi f_0(980) $, $B_s^0 to phi f_2(1270) $, and $B^0_s to phirho^0$ with branching fractions of $[1.12pm 0.16^{+0.09}_{-0.08}pm 0.11]times 10^{-6}$, $[0.61pm 0.13^{+0.12}_{-0.05}pm 0.06]times 10^{-6}$ and $[2.7pm 0.7pm 0.2pm 0.2]times 10^{-7}$, respectively.
We report a study of the suppressed decay B^- -> DK^-, D -> K^+pi^-pi^0, where D denotes either a D^0 or a bar{D}^0 meson. The decay is sensitive to the CP-violating parameter phi_3. Using a data sample of 772 x 10^6 Bbar{B} pairs collected at the Upsilon(4S) resonance with the Belle detector, we measure the ratio of branching fractions of the above suppressed decay to the favored decay B^- -> DK^-, D -> K^-pi^+pi^0. Our result is R_{DK} = [1.98 +/- 0.62(stat.) +/- 0.24(syst.)] x 10^{-2}, which indicates the first evidence of the signal for this suppressed decay with a significance of 3.2 standard deviations. We measure the direct CP asymmetry between the suppressed B^- and B^+ decays to be A_{DK} = 0.41 +/- 0.30 (stat.) +/- 0.05 (syst.). We also report measurements for the analogous quantities R_{Dpi} and A_{Dpi} for the decay B^- -> Dpi^-, D -> K^+pi^-pi^0.
Evidence for the hadronic annihilation decay mode $B^{+} to D_s^{+}phi$ is found with greater than $3sigma$ significance. The branching fraction and CP asymmetry are measured to be mathcal{B}(B^{+} to D_s^{+}phi) &=& (1.87^{+1.25}_{-0.73}({rm stat}) pm 0.19 ({rm syst}) pm 0.32 ({rm norm})) times 10^{-6}, mathcal{A}_{CP}(B^{+} to D_s^{+}phi) &=& -0.01 pm 0.41 ({rm stat}) pm 0.03 ({rm syst}). The last uncertainty on $mathcal{B}(B^{+} to D_s^{+}phi)$ is from the branching fractions of the $B^+ to D_s^+ kern 0.2embar{kern -0.2em D}{}^0$ normalization mode and intermediate resonance decays. Upper limits are also set for the branching fractions of the related decay modes $B^{+}_{(c)} to D^{+}_{(s)} K^{*0}$, $B^{+}_{(c)} to D^{+}_{(s)} kern 0.2embar{kern -0.2em K}{}^{*0}$ and ${B_c^{+} to D^{+}_{s}phi}$, including the result ${mathcal{B}(B^+ to D^+ K^{*0})} < 1.8 times 10^{-6}$ at the 90% credibility level.
We present the results of a Dalitz plot analysis of D^0 to K^0_S pi^0 pi^0 using the CLEO-c data set of 818 inverse pico-barns of e^+ e^- collisions accumulated at sqrt{s} = 3.77 GeV. This corresponds to three million D^0 D^0-bar pairs from which we select 1,259 tagged candidates with a background of 7.5 +- 0.9 percent. Several models have been explored, all of which include the K^*(892), K^*_2(1430), K^*(1680), the f_0(980), and the sigma(500). We find that the combined pi^0 pi^0 S-wave contribution to our preferred fit is (28.9 +- 6.3 +- 3.1)% of the total decay rate while D^0 to K^*(892)^0 pi^0 contributes (65.6 +- 5.3 +- 2.5)%. Using three tag modes and correcting for quantum correlations we measure the D^0 to K^0_S pi^0 pi^0 branching fraction to be (1.059 +- 0.038 +- 0.061)%.
The suppressed decay chain B- -> DK-, D -> K+pi-, where D indicates a anti-D0 or D0 state, provides important information on the CP-violating angle phi_3. We measure the ratio R_{DK} of the decay rates to the favored mode B- -> DK-, D -> K-pi+ to be R_{DK} = [1.63^{+0.44}_{-0.41}(stat)^{+0.07}_{-0.13}(syst)] x 10^{-2}, which indicates the first evidence of the signal with a significance of 4.1sigma. We also measure the asymmetry A_{DK} between the charge-conjugate decays to be A_{DK} = -0.39^{+0.26}_{-0.28}(stat)^{+0.04}_{-0.03}(syst). The results are based on the full 772 x 10^6 B anti-B pair data sample collected at the Upsilon(4S) resonance with the Belle detector.
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