I. Nakamura

Search for the decay B{sup 0}{yields}{gamma}{gamma}

The rare decay B0 -> gamma gamma is searched for in 104 fb^-1 of data, corresponding to 111 x 10^6 BBar pairs, collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. No evidence for the signal is found, and an upper limit of 6.2 x 10^-7 at 90% confidence level is set for the corresponding branching fraction.

Evidence for B{sup 0}{yields}{chi}{sub c1}{pi}{sup 0} at Belle

We present a measurement of the branching fraction for the Cabibbo- and color-suppressed B{sup 0}{yields}{chi}{sub c1}{pi}{sup 0} decay based on a data sample of 657x10{sup 6}BB events collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. We observe a signal of 40{+-}9 events with a significance of 4.7{sigma} including systematic uncertainties. The measured branching fraction is B(B{sup 0}{yields}{chi}{sub c1}{pi}{sup 0})=(1.12{+-}0.25(stat){+-}0.12(syst.))x10{sup -5}.

Observation of the decay {upsilon}(4S){yields}{upsilon}(1S){pi}{sup +}{pi}{sup -}

We study transitions between Y states with the emission of charged pions using 477 fb(-1) of data collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The measured product branching fraction B(Y(4S)-> Y(1S)pi(+)pi(-))xB(Y(1S)->mu(+)mu(-))=(4.42 +/- 0.81(stat)+/- 0.56(sys))x10(-6). When the PDG value for B(Y(1S)->mu(+)mu(-)) is used, this corresponds to B(Y(4S)-> Y(1S)pi(+)pi(-))=(1.78 +/- 0.33(stat)+/- 0.23(sys))x10(-4) and a partial decay width Gamma(Y(4S)-> Y(1S)pi(+)pi(-))=(3.65 +/- 0.67(stat)+/- 0.65(sys)) keV.

Study of the charmed baryonic decays B{sup 0}{yields}{sigma}{sub c}{sup ++}p{pi}{sup -} and B{sup 0}{yields}{sigma}{sub c}{sup 0}p{pi}{sup +}

We study the three-body charmed baryonic decays B0→Σ c++pπ- and B0→Σc0pπ+ in the four-body final state B0→Λc+pπ+π-, using a data sample of 357fb-1 accumulated at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure the branching fractions B(B0→Σc(2455)++pπ-)=(2.1±0.2±0. 3±0.5)×10-4, B(B0→Σc(2455)0pπ+)=(1. 4±0.2±0.2±0.4)×10-4 and B(B0→Σ c(2520)++pπ-)=(1.2±0.1±0.2±0.3)×10-4 with signal significances of 13.1σ, 9.4σ and 7.1σ, respectively. The errors are statistical, systematic, and due to the uncertainty in B(Λc+→pK-π+), respectively. We also set an upper limit B(B0→Σc(2520)0pπ+)<0.38×10-4 at the 90% confidence level. In addition, we obtain a nonresonant branching fraction of (6.4±0.4±0.9±1.7)×10-4, and a total branching fraction of (11.2±0.5±1.4±2.9)×10-4 for B0→Λc+pπ+π-.

Measurement of CP violation in B{sup 0}{yields}D*{sup -}{pi}{sup +} and B{sup 0}{yields}D{sup -}{pi}{sup +} decays

We report measurements of time-dependent decay rates for B{sup 0}{yields}D{sup (*)-}{pi}{sup +} decays and extraction of CP violation parameters that depend on {phi}{sub 3}. Using fully reconstructed D{sup (*)}{pi} events and partially reconstructed D*{pi} events from a data sample that contains 386x10{sup 6} BB pairs that was collected near the {upsilon}(4S) resonance, with the Belle detector at the KEKB asymmetric energy e{sup +}e{sup -} collider, we obtain the CP violation parameters S{sup +}(D{sup (*)}{pi}) and S{sup -}(D{sup (*)}{pi}). We obtain S{sup +}(D*{pi})=0.049{+-}0.020(stat){+-}0.011(sys), S{sup -}(D*{pi})=0.031{+-}0.019(stat){+-}0.011(sys), and S{sup +}(D{pi})=0.031{+-}0.030(stat){+-}0.012(sys), S{sup -}(D{pi})=0.068{+-}0.029(stat){+-}0.012(sys). These results are an indication of CP violation in B{sup 0}{yields}D*{sup -}{pi}{sup +} and B{sup 0}{yields}D{sup -}{pi}{sup +} decays at the 2.5{sigma} and 2.2{sigma} levels, respectively. If we use the values of R{sub D{sup (*}}{pi}} that are derived using assumptions of factorization and SU(3) symmetry, branching fraction measurements for the B{yields}D{sub s}{sup (*)}{pi} modes, and lattice QCD calculations, we can restrict the allowed region of |sin(2{phi}{sub 1}+{phi}{sub 3})| to be above 0.44 and 0.52 at 68% confidence level from the D*{pi} and D{pi} modes, respectively.

Improved measurement of the electroweak penguin process B{yields}X{sub s}l{sup +}l{sup -}

We present an improved measurement of the branching fraction for the electroweak penguin process B -> X-sl(l)+(-), where l is an electron or a muon and X-s is a hadronic system containing an s-quark. The measurement is based on a sample of 152x10(6) Upsilon(4S)-> B (B) over bar events collected with the Belle detector at the KEKB energy asymmetric e(+)e(-) collider. The X-s hadronic system is reconstructed from one K+/- or K-S(0) and up to four pions, where at most one pion can be neutral. Averaging over both lepton flavors, the inclusive branching fraction is measured to be B(B -> X-sl(l)+(-))=(4.11 +/- 0.83(stat)(-0.81)(+0.85)(syst))x10(-6) for M-l(l)+(-)> 0.2 GeV/c(2).

Improved measurement of CP-violation parameters sin2{phi}{sub 1} and |{lambda}|, B meson lifetimes, and B{sup 0}-B{sup 0} mixing parameter {delta}m{sub d}

Reference EPFL-ARTICLE-154416doi:10.1103/PhysRevD.71.072003View record in Web of Science Record created on 2010-11-05, modified on 2017-05-12