Study of B-0 -> rho(0)rho(0) decays, implications for the CKM angle phi(2) and search for other B-0 decay modes with a four-pion final state

We present a study of the branching fraction of the decay B-0 -> rho(0)rho(0) and the fraction of longitudinally polarized rho(0) mesons in this decay. The results are obtained from the final data sample containing 772 x 10(6) B (B) over bar pairs collected at the gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We find 166 +/- 59 B-0 -> rho(0)rho(0) events (including systematic uncertainties), corresponding to a branching fraction of B(B-0 -> rho(0)rho(0)) = (1.02 +/- 0.30(stat) +/- 0.15(syst)) x 10(-6) with a significance of 3.4 standard deviations and a longitudinal polarization fraction f(L) = 0.21(-0.22)(+0.18()stat) +/- 0.15(syst). We use the longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa matrix angle phi(2) = (84.9 +/- 13.5)degrees through an isospin analysis in the B ->rho rho system. We furthermore find 125 +/- 41 B-0 -> f(0)rho(0) events, corresponding to B(B-0 -> f(0)rho(0)) x B(f(0) -> pi(+)pi(-)) = (0.78 +/- 0.22(stat) +/- 0.11(syst)) x 10(-6), with a significance of 3.1 standard deviations. We find no other significant contribution with the same final state, and set upper limits at 90% confidence level on the (product) branching fractions, B(B-0 -> pi(+)pi(-)pi(+)pi(-)) < 11.2 x 10(-6), B(B-0 -> rho(0)pi(+)pi(-)) < 12.0 x 10(-6), B(B-0 -> f(0)pi(+)pi(-)) x B(f(0) -> pi(+)pi(-)) < 3.0 x 10(-6) and B(B-0 -> f(0)f(0)) x B(f(0) -> pi(+)pi(-))(2) < 0.2 x 10(-6).

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Tagir Aushev, Donghyun Kim, Ji Hyun Kim, Jing Li, Olivier Schneider, Mingkui Wang, Xiao Wang
Amer Physical Soc, 2014
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https://infoscience.epfl.ch/record/198882?ln=fr

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Search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi(-) decays

Tagir Aushev, Sun Hee Kim, Donghyun Kim, Ji Hyun Kim, Lei Li, Yiming Li, Olivier Schneider, Mingkui Wang, Xiao Wang

We report the results of a search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi thorn p-decays. This study is based on a data sample corresponding to an integrated luminosity of 711 fb(-1), collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We investigate the J/psi pi(+)pi(-) thorn p-invariant mass distribution in the range 4.0 to 4.6 GeV/c(2) using both B+ -> J/psi pi(+)pi K--(+) and B-0 -> J/psi pi(+)pi K--(S)0 decays. We find excesses of events above the background levels, with significances of 2.1 and 0.9 standard deviations for charged and neutral B -> Y(4260)K decays, respectively, taking into account the systematic uncertainties. These correspond to upper limits on the product of branching fractions, B(B+ -> Y(4260)K+) x B(Y(4260) -> J/psi pi(+)pi(-)) < 1.4 x 10(-5) and B(B-0 -> Y(4260)K-0) x B(Y(4260) -> J/psi pi(+)pi(-)) < 1.7 x 10(-5) at the 90% confidence level.

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Search for B-s(0) -> hh decays at the Y(5S) resonance

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We have searched for B-s(0) --> hh decays, where h stands for a charged or neutral kaon, or a charged pion. These results are based on a 23: 6 fb(-1) data sample collected with the Belle detector on the Y(5S) resonance at the KEKB asymmetric-energy e(+)e(-) collider, containing 1.25 x 10(6) B-s(()())(B) over bar (()(s)()) events. We observe the decay B-s(0) --> K+K- and measure its branching fraction, B(B-s(0) --> K+K-) = [3.8(-0.9)(+1.0)(stat) +/- 0.5(syst) +/- 0.5(f(s))] x 10(-5). The first error is statistical, the second is systematic, and the third error is due to the uncertainty in the B-s(0) production fraction in e(+)e(-) --> b (b) over bar events. No significant signals are seen in other decay modes, and we set upper limits at the 90% confidence level: B(B-s(0) --> K- pi+) < 1.2 x 10(-5), B(B-s(0) --> pi(+)pi(-)) < 2.6 x 10(-5), and B(B-s(0) --> K-0(K) over bar (0)) < 6.6 x 10(-5).

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Evidence for Direct CP Violation in B-+/- -> eta h(+/-) and Observation of B-0 -> eta K-0

Tagir Aushev, Ji Hyun Kim, Jing Li, Zhen Liu, Remi Léandre Albert Louvot, Olivier Schneider, Mingkui Wang

We report measurements of the branching fractions and CP asymmetries for B-+/- -> eta h(+/-) (h = K or pi) and the observation of the decay B-0 -> eta K-0 from the final data sample of 772 x 10(6) B (B) over bar pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The measured branching fractions are B(B-+/- -> eta K-+/-) = (2.12 +/- 0.23 +/- 0.11) x 10(-6), B(B-+/- -> eta pi(+/-)) = (4.07 +/- 0.26 +/- 0.21) x 10(-6), and B(B-0 -> eta K-0) = (1.27(-0.29)(+0.33) +/- 0.08) x 10(-6), where the last decay is observed for the first time with a significance of 5.4 standard deviations (sigma). We also find evidence for CP violation in the charged B modes, A(CP)(B-+/- -> eta K-+/-) = -0.38 +/- 0.11 +/- 0.01 and A(CP)(B-+/- -> eta pi(+/-)) = -0.19 +/- 0.06 +/- 0.01 with significances of 3.8 sigma and 3.0 sigma, respectively. For all measurements, the first and second uncertainties are statistical and systematic, respectively.

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