Measurement of the time-dependent CP asymmetries in B0-->K(S)(0)rho(0)gamma decays

We report the first measurement of time-dependent CP asymmetry in B(0)-->K(S)(0)rho(0)gamma decays based on 657 x 10(6) BB pairs collected with the Belle detector at the KEKB asymmetric-energy collider. We measure the CP-violating parameter S_{K_{S};{0}rho;{0}gamma}=0.11+/-0.33(stat)-0.09+0.05(syst) from a signal of 212+/-17 events. We also obtain the effective direct CP-violating parameter A{eff}=0.05+/-0.18(stat)+/-0.06(syst) for mK(S)0pi+pi- <1.8 GeV/c(2) and 0.6 GeV/c(2)<m pi+pi- <0.9 GeV/c2.

Evidence for neutral B meson decays to omegaK*0

We present the results of a study of the charmless vector-vector decay B0-->omegaK*0 with 657 x 10(6) BB pairs collected with the Belle detector at the KEKB e+e- collider. We measure the branching fraction to be B(B0-->omegaK*0) = [1.8+/-0.7(stat)+/-0.3(syst)]x 10(-6) with 3.0sigma significance. We also perform a helicity analysis of the omega and K*0 vector mesons, and obtain the longitudinal polarization fraction fL(B0-->omegaK*0) = 0.56+/-0.29(stat) -0.08(+0.18)(syst). Finally, we measure a large nonresonant branching fraction B[B0-->omegaK+pi(-);M Kpi in(0.755,1.250) GeV/c2] = [5.1+/-0.7(stat)+/-0.7(syst)]x 10(-6) with a significance of 9.5sigma.

Observation of a near-threshold enhancement in the e+e- -->Lambda+_(c)Lambda-_(c) cross section using initial-state radiation

We report a measurement of the exclusive e+ e- -->Lambda+_(c)Lambda-_(c) cross section as a function of center-of-mass energy near the Lambda+_(c)Lambda-_(c) threshold. A clear peak with a significance of 8.2sigma is observed in the Lambda+_(c)Lambda-_(c) invariant mass distribution just above threshold. With an assumption of a resonance origin for the observed peak, a mass and width of M=[4634 (+8)_(-7)(stat)(+5)_(-8)(syst)] MeV/c(2) and Gamma_(tot)=[92 (+40)_(-24)(stat)(+10)_(-21)(syst)] MeV are determined. The analysis is based on a study of events with initial-state-radiation photons in a data sample collected with the Belle detector at the Upsilon(4S) resonance and nearby continuum with an integrated luminosity of 695 fb(-1) at the KEKB asymmetric-energy e+ e- collider.

Observation of B{0}-->ppK*0 with a large K*0 polarization

Using a 492 fb{-1} data sample collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider, we observe the decay B{0}-->ppK*0 with a branching fraction of (1.18{-0.25}{+0.29}(stat)+/-0.11(syst))x10{-6}. We study the decay dynamics of B{0}-->ppK*0 and compare with B{+}-->ppK*+. The K*0 meson is found to be almost 100% polarized (with a fraction of (101+/-13+/-3)% in the helicity zero state), while the K*+ meson has a (32+/-17+/-9)% fraction in the helicity zero state. The direct CP asymmetries for B{0}-->ppK*0 and B{+}-->ppK*+ are measured to be -0.08+/-0.20+/-0.02 and -0.01+/-0.19+/-0.02, respectively. In addition, we report improved measurements of the branching fractions B(B{+}-->ppK*+)=(3.38{-0.60}{+0.73}+/-0.39)x10{-6} and B(B{0}-->ppK{0})=(2.51{-0.29}{+0.35}+/-0.21)x10{-6}, which supersede our previous measurements.

Measurement of B(Ds{+}-->mu+nu(mu))

We present a measurement of the branching fraction B(D{s}{+}-->mu{+}nu{mu}) using a 548 fb{-1} data sample collected by the Belle experiment at the KEKB e{+}e{-} collider. The D{s} momentum is determined by reconstruction of the system recoiling against DKgammaX in events of the type e{+}e{-}-->D{s}{*}DKX, D{s}{*}-->D{s}gamma, where X represents additional pions or photons from fragmentation. This full-reconstruction method provides high resolution in the neutrino momentum and thus good background separation, equivalent to that achieved by experiments at the tau-charm factories. We obtain the branching fraction B(D{s}{+}-->mu{+}nu{mu})=[6.44+/-0.76(stat)+/-0.57(syst)]x10{-3}, implying a D{s} decay constant of f{D{s}}=[275+/-16(stat)+/-12(syst)] MeV.

Production of new charmoniumlike states in e+e- -->J/psiD*D[over](*) at sqrt[s] approximately 10.6 GeV

We report a study of the processes e+e- -->J/psiD*D[over](*). In J/psiD*D[over]* we observe a significant enhancement in the D*D[over]* invariant mass spectrum, which we interpret as a new charmoniumlike state and denote X(4160). The X(4160) parameters are M=(4156(-20)+25+/-15) MeV/c2 and Gamma=(139(-61)+111+/-21) MeV. We also report a new measurement of the X(3940) mass and width: M=(3942(-6)+7+/-6) MeV/c2 and Gamma=(37(-15)+26+/-8) MeV. The analysis is based on a 693 fb(-1) data sample recorded near the Upsilon(4S) resonance by the Belle detector at the KEKB asymmetric-energy collider.

Observation of a resonancelike structure in the pi +- psi' mass distribution in exclusive B-->Kpi +- psi' decays

A distinct peak is observed in the pi +/- psi' invariant mass distribution near 4.43 GeV in B-->K pi +/- psi' decays. A fit using a Breit-Wigner resonance shape yields a peak mass and width of M=4433+/-4(stat)+/-2(syst) MeV and Gamma=45-13+18(stat)-13+30(syst) MeV. The product branching fraction is determined to be B(B 0-->K -/+Z+/-(4430)) x B(Z+/-(4430)-->pi+/-psi')=(4.1+/-1.0(stat)+/-1.4(syst)) x 10(-5), where Z+/-(4430) is used to denote the observed structure. The statistical significance of the observed peak is 6.5 sigma. These results are obtained from a 605 fb(-1) data sample that contains 657 x 10(6) BB pairs collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider.

Measurement of time-dependent CP-violating parameters in B(0)-->K_(S)(0)K_(S)(0) decays

We report a measurement of the CP-violating parameters in B;{0}-->K_{S}{0}K_{S}{0} decays based on a data sample of 657x10{6} BB[over ] pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e;{+}e{-} collider. In this Letter, one neutral B meson is fully reconstructed in the B;{0}-->K_{S}{0}K_{S}{0} decay mode, and the flavor of the accompanying B meson is identified by its decay products. The CP-violating parameters are measured from the asymmetry in the distributions of the proper-time interval between the two B decays: S_K_{S}{0}K_{S}{0}}=-0.38_{-0.77}{+0.69}(stat)+/-0.09(syst) and A_{K_{S}{0}K_{S}{0}}=-0.38+/-0.38(stat)+/-0.05(syst).

Observation of a new DsJ meson in B+-->D0D0K+ decays

We report the observation of a new DsJ meson produced in B+-->D0DsJ-->D0D0K+. This state has a mass of M=2708+/-9(-10)(+11) MeV/c2, a width Gamma=108+/-23(-31)(+36) MeV/c2 and a 1- spin-parity. The statistical significance of this observation is 8.4 sigma. The results are based on an analysis of 449 x 10(6) BB events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Observation of the psi(4415)-->DD2*(2460) decay using initial-state radiation

We report measurements of the exclusive cross section for e(+)e(-)-->D(0)D(-)pi(+) over the center-of-mass energy range 4.0 GeV to 5.0 GeV with initial-state radiation and the first observation of the decay psi(4415)-->D(0)D(-)pi(+). From a study of the resonant substructure in psi(4415) decay we conclude that the psi(4415)-->D(0)D(-)pi(+) decay is dominated by psi(4415)-->DD(2)(*)(2460). We obtain B(psi(4415)-->D(0)D(-)pi(nonresonant)(+))/B(psi(4415)-->DD(2)(*)(2460)-->D(0)D(-)pi(+))<0.22 at 90% C.L. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 fb(-1).

Search for the CP-violating decays Upsilon(4S)-->B0B0-->J/psiKS0+J/psi(etac)KS0

We report the first search for CP-violating decays of the Upsilon(4S) using a data sample that contains 535 x 10(6) Upsilon(4S) mesons with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. A partial reconstruction technique is employed to enhance the signal sensitivity. No significant signals were observed. We obtain an upper limit of 4 x 10(-7) at the 90% confidence level for the branching fractions of the CP violating modes, Upsilon(4S)-->B(0)B(0)-->J/psiK(S)(0)+J/psi(eta(c))K(S)(0). Extrapolating the result, we find that an observation with 5sigma significance is expected with a 30 ab(-1) data sample, which is within the reach of a future super B factory.

Observation of B(0)-->D(*-)tau(+)nu(tau) decay at Belle

We report an observation of the decay B{0}-->D{*-}tau{+}nu{tau} in a data sample containing 535x10{6} BB pairs collected with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider. We find a signal with a significance of 5.2sigma and measure the branching fraction B(B{0}-->D{*-}tau{+}nu{tau})=(2.02{-0.37}{+0.40}(stat)+/-0.37(syst))%. This is the first observation of an exclusive B decay with a b-->ctaunu{tau} transition.

Measurement of the e+e- -->pi+pi- J/psi cross section via initial-state radiation at Belle

The cross section for e(+)e(-)-->pi(+)pi(-)J/psi between 3.8 and 5.5 GeV/c(2) is measured using a 548 fb(-1) data sample collected on or near the Upsilon(4S) resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c(2), corresponding to the so called Y(4260), is observed. In addition, there is another cluster of events at around 4.05 GeV/c(2). A fit using two interfering Breit-Wigner shapes describes the data better than one that uses only the Y(4260), especially for the lower-mass side of the 4.25 GeV enhancement.

Observation of two resonant structures in e+ e- -->pi+ pi- psi(2S) via initial-state radiation at Belle

The cross section for e+ e- --> pi+ pi- psi(2S) between threshold and sqrt[s]=5.5 GeV is measured using 673 fb(-1) of data on and off the Upsilon(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the pi+ pi- psi(2S) invariant-mass distribution, one at 4361 +/- 9 +/- 9 MeV/c2 with a width of 74 +/- 15 +/- 10 MeV/c2, and another at 4664 +/- 11 +/- 5 MeV/c2 with a width of 48 +/- 15 +/- 3 MeV/c2, if the mass spectrum is parametrized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.

Measurements of branching fractions for B --> K pi and B --> pi pi decays

We report measurements of branching fractions for B --> K pi and B --> pi pi decays based on a data sample of 449 x 10(6) BB[over] pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We also measure the ratios of partial widths for B-->Kpi decays, namely R(c) identical with 2Gamma(B(+) --> K(+) pi(0))/Gamma(B(+) --> K(0) pi(+)) = 1.08+/-0.06+/-0.08 and R(n) identical with Gamma(B(0) --> K(+) pi(-))/2 Gamma(B(0) --> K(0) pi(0)) = 1.08+/-0.08+/-0.08, where the first and the second errors are statistical and systematic, respectively. These ratios are sensitive to enhanced electroweak penguin contributions from new physics; the new measurements are, however, consistent with standard model expectations.

Measurement of the tau lepton mass and an upper limit on the mass difference between tau+ and tau-

The mass of the tau lepton has been measured in the decay mode tau-->3pinutau using a pseudomass technique. The result obtained from 414 fb-1 of data collected with the Belle detector is Mtau=[1776.61+/-0.13(stat)+/-0.35(sys)] MeV/c2. The upper limit on the relative mass difference between positive and negative tau leptons is |Mtau+-Mtau-|/Mtau<2.8 x 10-4 at 90% confidence level.

Experimental constraints on the spin and parity of the Lambdac(2880)+

We report the results of several studies of the Lambda(c)(+)pi(+)pi(-)X final state in continuum e(+)e(-) annihilation data collected by the Belle detector. An analysis of angular distributions in Lambda(c)(2880)(+)-->Sigma(c)(2455)(0,++)pi(+,-) decays strongly favors a Lambda(c)(2880)(+) spin assignment of 5/2 over 3/2 or 1/2. We find evidence for Lambda(c)(2880)(+)-->Sigma(c)(2520)(0,++)pi(+,-) decay and measure the ratio of Lambda(c)(2880)(+) partial widths Gamma(Sigma(c)(2520)pi)/Gamma(Sigma(c)(2455)pi)=0.225+/-0.062+/-0.025. This value favors the Lambda(c)(2880)(+) spin-parity assignment of 5/2(+) over 5/2(-). We also report the first observation of Lambda(c)(2940)(+)-->Sigma(c)(2455)(0,++)pi(+,-) decay and measure Lambda(c)(2880)(+) and Lambda(c)(2940)(+) mass and width parameters. These studies are based on a 553 fb(-1) data sample collected at or near the Upsilon(4S) resonance at the KEKB collider.

Measurement of CP asymmetry in a time-dependent Dalitz analysis of B0-->(rhopi)0 and a constraint on the quark mixing matrix angle phi2

We present a measurement of CP asymmetry using a time-dependent Dalitz plot analysis of B0-->pi+pi-pi0 decays based on a 414 fb(-1) data sample containing 449 x 10(6) BB pairs. The data was collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider. Combining our analysis with information on charged B decay modes, we perform a full Dalitz and isospin analysis and obtain a constraint on the CKM angle phi2, 68 degrees < phi2 < 95 degrees as the 68.3% confidence interval for the phi2 solution consistent with the standard model (SM). A large SM-disfavored region also remains.

Observation of direct CP violation in B0 --> pi+pi- decays and model-independent constraints on the quark-mixing angle phi2

We report a new measurement of the time-dependent CP-violating parameters in B(0)-->pi(+)pi(-) decays with 535 x 10(6) BB pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider operating at the Upsilon(4S) resonance. We find 1464+/-65 B(0)-->pi(+)pi(-) events and measure the CP-violating parameters S(pipi)=-0.61+/-0.10(stat)+/-0.04(syst) and A(pipi)=+0.55+/-0.08(stat)+/-0.05(syst). We observe large direct CP violation with a significance greater than 5 standard deviations for any S(pipi) value. Using isospin relations, we measure the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle phi(2)=(97+/-11) degrees for the solution consistent with the standard model and exclude the range 11 degrees <phi(2)<79 degrees at the 95% confidence level.

Observation of B decays to two kaons

Using 449x10(6) BB[over ] pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider, we observe clear signals for B(+)-->K[over ](0)K(+) and B(0)-->K[over ](0)K(0) decays with 5.3sigma and 6.0sigma significance, respectively. We measure the branching fractions B(B(+)-->K[over ](0)K(+))=(1.22(-0.28-0.16)(+0.32+0.13))x10(-6) and B(B(0)-->K[over ](0)K(0))=(0.87(-0.20)(+0.25)+/-0.09)x10(-6), and partial-rate asymmetries A(CP)(B(+)-->K[over ](0)K(+))=0.13(-0.24)(+0.23)+/-0.02 and A(CP)(B(0)-->K[over ](0)K(0))=-0.58(-0.66)(+0.73)+/-0.04. From a simultaneous fit, we also obtain B(B(+)-->K(0)pi(+))=(22.8(-0.7)(+0.8)+/-1.3)x10(-6) and A(CP)(B(+)-->K(0)pi(+))=0.03+/-0.03+/-0.01. The first and second error in the branching fractions and the partial-rate asymmetries are statistical and systematic, respectively. No signal is observed for B(0)-->K(+)K(-) decays, and for this branching fraction, we set an upper limit of 4.1x10(-7) at the 90% confidence level.

Search for invisible decay of the Upsilon(1S)

We report results of a search for the invisible decay of the Upsilon(1S) via the Upsilon(3S)-->pi+ pi- Upsilon(1S) transition using a data sample of 2.9 fb-1 at the Upsilon(3S) resonance. The data were collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. No signal is found, and an upper limit for the branching fraction at the 90% confidence level is determined to be B(Upsilon(1S)-->invisible)<2.5 x 10(-3).

Observation of the decay B(0)-->J/psieta

We report the first observation of B(0)-->J/psieta decay. These results are obtained from a data sample that contains 449 x10(6) BB[over] pairs accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We observe a signal with a significance of 8.1 sigma and obtain a branching fraction of (9.5+/-1.7(stat)+/-0.8(syst)) x 10(-6).

Measurement of the near-threshold e+e- --> D(*)+/-D(*)-/+ cross section using initial-state radiation

We report a measurement of the exclusive e+e- -->D(*)+/-D*-/+ cross section as a function of center-of-mass energy near the D(*)+/-D*-/+ threshold with initial-state radiation. A partial reconstruction technique is used to increase the efficiency and to suppress background. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 547.8 fb(-1).

Observation of a charmoniumlike state produced in association with a J/psi in e+e- annihilation at sqrt[s] approximately equal to 10.6 GeV

We report the first observation of a charmoniumlike state recoiling from the J/psi in the inclusive process e+e- -->J/psi+anything at a mass of (3.943+/-0.006+/-0.006) GeV/c{2}. We also observe the decay of this state into D*D[over ] and determine its intrinsic width to be less than 52 MeV/c{2} at the 90% C.L. These results are obtained from a 357 fb{-1} data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric-energy e+e- collider.

Measurement of inclusive Ds, D0, and J/psi rates and determination of the Bs(*)Bs(*) production fraction in bb Events at the Upsilon(5S) resonance

The inclusive production of D(s), D(0), and J/psi mesons is studied using a 1.86 fb(-1) data sample collected on the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The number of bb events in this Upsilon(5S) data sample is determined. We measure the branching fractions B(Upsilon(5S)-->D(s)X)/2=(23.6+/-1.2+/-3.6)%, B(Upsilon(5S)-->D(0)X)/2=(53.8+/-2.0+/-3.4)%, and B(Upsilon(5S)-->J/psiX)/2=(1.030+/-0.080+/-0.067)%. From the D(s) and D(0) inclusive branching fractions the ratio f(s)=(18.0+/-1.3+/-3.2)% of B(s)(*)B(s)(*) to the total bb quark pair production at the Upsilon(5S) energy is obtained in a model-dependent way.

Evidence of the purely leptonic decay B- --> tau- nu(tau)

We present the first evidence of the decay B- --> tau- nu(tau), using 414 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics and measure the branching fraction to be B(B- --> tau- nu(tau)) = (1.79(-0.49) +0.56(stat)(-0.51) +0.46(syst)) x 10(-4). This implies that fB = 0.229(-0.031) +0.036(stat)(-0.037) +0.034(syst) GeV and is the first direct measurement of this quantity.

Observation of B+ --> Lambda c+ Lambda c- K+ and B0 --> Lambda c+ Lambda c- K0 decays

We report the first measurements of the doubly charmed baryonic B decays B --> Lambda c+ Lambda c- K. The B+ --> Lambda c+ Lambda c- K+ decay is observed with a branching fraction of (6.5(-0.9)(+1.0)+/-1.1+/-3.4)x10(-4) and a statistical significance of 15.4sigma. The B0 --> Lambda c+ Lambda c- K0 decay is observed with a branching fraction of (7.9(-2.3)(+2.9)+/-1.2+/-4.1)x10(-4) and a statistical significance of 6.6sigma. The branching fraction errors are statistical, systematic, and the error resulting from the uncertainty of the Lambda c+ --> pK- pi+ decay branching fraction. The analysis is based on 357 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.

Observation of new states decaying into Lambda(c)(+)Kappa(-)pi(+) and Lambda(c)(+)Kappa(0)/(s)pi(-)

We report the first observation of two charmed strange baryons that decay into Lambda(c)(+)Kappa(-)pi(+). The broader of the two states is measured to have a mass of 2978.5+/-2.1+/-2.0 MeV/c2 and a width of 43.5+/-7.5+/-7.0 MeV/c2. The mass and width of the narrow state are measured to be 3076.7+/-0.9+/-0.5 MeV/c;{2} and 6.2+/-1.2+/-0.8 MeV/c2, respectively. We also perform a search for the isospin partner states that decay into Lambda(c)(+)Kappa(0)/(s)pi(-) and observe a significant signal at the mass of 3082.8+/-1.8+/-1.5 MeV/c2. The data used for this analysis were accumulated at or near the Upsilon(4S) resonance, using the Belle detector at the e+ e- asymmetric-energy collider KEKB. The integrated luminosity of the data sample used is 461.5 fb(-1).

Evidence for B-->eta'pi and improved measurements for B-->eta'K

We report evidence for the exclusive two-body charmless hadronic B meson decay B-->eta'pi, and improved measurements of B-->eta'K. The results are obtained from a data sample of 386x10(6) BB pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure B(B+-->eta'pi+)=[1.76(-0.62)(+0.67)(stat)(-0.14)(+0.15)(syst)]x10(-6) and B(B0-->eta'pi0)=[2.79(-0.96)(+1.02)(stat)(-0.34)(+0.25)(syst)]x10(-6). We also find the ratio of B(B+-->eta'K+)/B(B0-->eta'K0)=1.17+/-0.08(stat)+/-0.03(syst) and measure the direct CP asymmetries for the charged modes.

Measurement of D0-->pilnu(Klnu) form factors and absolute branching fractions

Using a 282 fb-1 data sample collected by the Belle experiment at the KEKB e+e- collider, we study D0 decays to K-l+nu and pi-l+nu final states. The D0 flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q2=(pl+pnu)2. Normalizing to the total number of D0 tags, we measure the absolute branching fractions to be B(D0-->Klnu)=(3.45+/-0.07stat+/-0.20syst)% and B(D0-->pilnu)=(0.255+/-0.019stat+/-0.016syst)% and the semileptonic form factors (within the modified pole model) f+K(0)=0.695+/-0.007stat+/-0.022syst and f+pi(0)=0.624+/-0.020stat+/-0.030syst.

Evidence for large direct CP violation in B+/- --> rho(770)0K+/- from analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decays

We report results on a Dalitz analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decay including searches for direct CP violation. We report the first observation of the decay B+/- --> f2(1270)K+/- with a statistical significance above 6sigma. We also observe first evidence for large direct CP violation in the B+/- --> rho(770)0K+/- channel. The results are obtained with a data sample that contains 386 10(6) BB pairs collected at the Y(4s) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Observation of b-->dgamma and determination of /Vtd/Vts/

We report the observation of the flavor-changing neutral current process b-->dgamma using a sample of 386 x 106 B meson pairs accumulated by the Belle detector at the KEKB e+e- collider. We measure branching fractions for the exclusive modes B--->rho-gamma, B0rho0gamma, and B0omegagamma. Assuming that these three modes are related by isospin, we find B(B-->(rho,gamma)gamma)=[Formula: See Text] with a significance of 5.1sigma. This result is used to determine the ratio of Cabibbo-Kobayashi-Maskawa matrix elements /Vtd/Vts/ to be [Formula: See Text].

Measurement of the branching fraction, polarization, and asymmetry for decays, and determination of the Cabibbo-Kobayashi-Maskawa phase

We have measured the branching fraction , longitudinal polarization fraction f(L), and CP asymmetry coefficients A and S for B(0) --> rho(+) rho(-) decays with the Belle detector at the KEKB e(+) e(-) collider using 253 Fb(-1) of data. We obtain B = [22.8 +/- 3.8(stat)(+2.3)(-2.6)(syst)] x 10(-6), f(L) = 0.941 (+0.034)(-0.040)(stat) +/- 0.030(syst). A = 0.00 +/- 0.30(stat) +/- 0.09(syst) and S = 0.08 +/- 0.09(syst). These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase ; the solution consistent with the standard model is phi(2) = (88 +/- 17) degrees or 59 degrees < phi(2) < 115 degrees at 90% C.L.

Improved constraints on D0-D0 mixing in D0 --> K+ pi- decays from the Belle detector

We report the results of a search for D0-D0 mixing in D0 --> K+ pi- decays based on 400 fb(-1) of data accumulated by the Belle detector at KEKB. Both assuming CP conservation and allowing for CP violation, we fit the decay-time distribution for the mixing parameters x and y, as well as for the parameter R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays. The 95% confidence level region in the (x'2,y') plane is obtained using a frequentist method. Assuming CP conservation, we find x'2 < 0.72 x 10(-3) and -9.9 x 10(-3) < y' < 6.8 x 10(-3) at the 95% confidence level; these are the most stringent constraints on the mixing parameters to date. The no-mixing point (0,0) has a confidence level of 3.9%. Assuming no mixing, we measure R(D) = (0.377 +/- 0.008 +/- 0.005)%.

Observation of a chi(c2)' candidate in gamma gamma --> DD production at belle

We report on a search for new resonant states in the process gamma gamma --> DD. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c2. The production rate and the angular distribution in the gamma gamma center-of-mass frame suggest that this state is the previously unobserved chi(c2)', the 2(3)P2 charmonium state.

Measurements of B decays to two kaons

We report measurements of B meson decays to two kaons using 253 fb(-1) of data collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider. We find evidence for signals in B+ --> K0 K+ and B0 --> K0 K0 with significances of 3.0sigma and 3.5sigma, respectively. (Charge-conjugate modes are included.) The corresponding branching fractions are measured to be [symbol: see text](B+ --> K0 K+) = (1.0 +/- 0.4 +/- 0.1) x 10(-6) and [symbol: see text](B0 --> K0 K0) = (0.8 +/- 0.3 +/- 0.1) x 10(-6). These decay modes are examples of hadronic bd transitions. No signal is observed in the decay B0 --> K+ K-, and we set an upper limit of 3.7 x 10(-7) at 90% confidence level.

Measurement of the wrong-sign decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi-, and search for CP violation

Using 281 fb-1 of data from the Belle experiment recorded at or near the (4S) resonance, we have measured the rates of the "wrong-sign" decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi- relative to those of the Cabibbo-favored decays D0 --> K- pi+ pi0 and D0 --> K- pi+ pi+ pi-. These wrong-sign decays proceed via a doubly Cabibbo-suppressed amplitude or via D0-D0 mixing; the latter has not yet been observed. We obtain R(WS)(K pi pi0) = [0.229 +/- 0.015(stat)(+0.013)(-0.009)(syst)]% and R(WS)(K3pi) = [0.320 +/- 0.018(stat)(+0.018)(0.013)(syst)]%. The CP asymmetries are measured to be -0.006 +/- 0.053 and -0.018 +/- 0.044 for the K+ pi- pi0 and K+ pi- pi+ pi- final states, respectively.

Observation of B+ --> plambdagamma

We report the first observation of the radiative hyperonic B decay B+ --> plambdagamma, using a 140 fb(-1) data sample recorded on upsilom(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The measured branching fraction is [symbol: see text](B+ --> plambdagamma) = (2.16(+0.58)(-0.53) +/- 0.20) x 10(-6). We examine its M(plambda) distribution and observe a peak near threshold. This feature is expected by the short-distance b --> sgamma transition. A search for B+ --> pepsilon0gamma yields no significant signal, and we set a 90% confidence-level upper limit on the branching fraction of [symbol: see textB+ --> pepsilon0gamma <4.6 x 10(-6).

Evidence for B0 --> D+ D- and observation of B- --> D0D- and B- -->D0D*- decays

We report evidence for B(0) --> D(0)D(-) and the first observation of the decay modes B(-) --> D(0)D(-) and B(-) --> D(0)D(*-) based on a sample of 152 x 10(6) BB events collected by the Belle detector at KEKB. The branching fractions for B(0) --> D(+) D(-), B--->D(0)D(-), and B--> D(0)D(*-) are found to be (1.91 +/- 0.51 +/- 0.30) x10(-4), (4.83 +/- 0.78 +/- 0.58) x 10(-4), and (4.57 +/- 0.71 +/- 0.56) x 10(-4), respectively. Charge asymmetries in the B---> D(0)D(-) and B(-) --> D(0)D(*-) channels are consistent with zero.

Measurement of the time-dependent CP-violating asymmetry in B(0)-->K(0)(S)pi(0)gamma decays

We present a new measurement of CP-violation parameters in B(0)-->K(0)(S)pi(0)gamma decay based on a sample of 275 x 10(6) BB pairs collected at the Gamma(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. One of the B mesons is fully reconstructed in the B(0)-->K(0)(S)pi(0)gamma decay. The flavor of the accompanying B meson is identified from its decay products. CP-violation parameters are obtained from the asymmetry in the distribution of the proper time intervals between the two B decays. We obtain SK(0)(S)(pi(0)gamma) = -0.58(+0.46)(-0.38)(stat) +/- 0.11(syst) and AK(0)(S)(pi(0)gamma) = +0.03 +/- 0.34(stat) +/- 0.11(syst), for the K(0)(S)pi(0) invariant mass covering the full range up to 1.8 GeV/c2. We also measure the CP-violation parameters for the case B(0)-->K(*0)(-->K(0)(S)pi(0))gamma and obtain S(K(*0)gamma) = -0.79(+0.63)(-0.50)(stat) +/- 0.10(syst) for A(K(*0)gamma) fixed at 0.

Measurement of polarization and triple-product correlations in B-->phiK* decays

We present measurements of decay amplitudes and triple-product correlations in B-->phiK* decays based on 253 fb(-1) of data recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. The decay amplitudes for the three different helicity states are determined from the angular distributions of final-state particles. The longitudinal polarization amplitudes are found to be 0.45 +/- 0.05 +/- 0.02 for B0-->phiK(*0) and 0.52 +/- 0.08 +/- 0.03 for B+ -->phiK(*+) decays. CP- and T-odd CP-violating triple-product asymmetries are measured to be consistent with zero.

Observation of the D1(2420)-->Dpi + pi- decays

We report on the first observation of D0/1(2420)-->D0pi- pi+ and D+/1(2420-->D+ pi- pi+ decays (where the contribution from the dominant known D1-->D*pi decay mode is excluded) in the B- -->D0/1pi-) and (-)B0-->D+/1pi- decays, respectively. The observation is based on 15.2 x 10(7) B(-)B events collected with the Belle detector at the KEKB collider. We also set 90% confidence level upper limits for the branching fractions of the four following decays: B- -->D0/1pi-, D01-->D(*0)pi- pi+, (-)B0-->D+/1pi-, D+/1-->D(*+) pi- pi+, B- -->D(*0)2(2460)pi-, D(*0)2 -->D(*0) pi- pi+, (-)B0-->D(*+)2(2460)pi-, D(*+)2-->D(*+)pi- pi+.

Observation of a near-threshold omegaJ/psi mass enhancement in exclusive B-->KomegaJ/psi decays

We report the observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/psi decays. The results are obtained from a 253 fb(-1) data sample that contains 275 x 10(6) BB pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. The statistical significance of the omegaJ/psi mass enhancement is estimated to be greater than 8sigma.

Observation of B0-->pi0pi0

We report the observation of the decay B0-->pi(0)pi(0), using a 253 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) collider. The measured branching fraction is B(B0-->pi(0)pi(0))=(2.3(+0.4+0.2)(-0.5-0.3))x10(-6), with a significance of 5.8 standard deviations including systematic uncertainties. We also make a measurement of the direct CP violating asymmetry in this mode.

Observation of an isotriplet of excited charmed baryons decaying to lambda+c pi

We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences M(Lambda(+)(c)pi)-M(Lambda(+)(c)) and widths to be 515.4(+3.2+2.1)(-3.1-6.0) MeV/c(2), 61(+18+22)(-13-13) MeV for the neutral state; 505.4(+5.8+12.4)(-4.6-2.0) MeV/c(2), 62(+37+52)(-23-38) MeV for the charged state; and 514.5(+3.4+2.8)(-3.1-4.9) MeV/c(2), 75(+18+12)(-13-11) MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider.

Study of B0-->rho+/- pi-/+ time-dependent CP violation at Belle

We present a time-dependent analysis of CP violation in B0-->rho(+/-)pi(-/+) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at KEKB. We obtain the charge asymmetry A(rhopi)(CP)=-0.16+/-0.10(stat)+/-0.02(syst). An unbinned maximum-likelihood fit to the Deltat distributions yields C(rhopi)=0.25+/-0.17(stat)+0.02-0.06(syst), DeltaC(rhopi)=0.38+/-0.18(stat)+0.02-0.04(syst), S(rhopi)=-0.28+/-0.23(stat)+0.10-0.08(syst), and DeltaS(rhopi)=-0.30+/-0.24(stat)+/-0.09(syst). The direct CP violation parameters for B-->rho(+)pi(-) and B-->rho(-)pi(+) decays are A(+-)(rhopi)=-0.02+/-0.16(stat)+0.05-0.02(syst) and A(-+)(rhopi)=-0.53+/-0.29(stat)+0.09-0.04(syst).

Observation of B+-->K1(1270)+gamma

We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma)<1.5 x 10(-5) at the 90% confidence level. We also measure inclusive branching fractions for B+-->K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)<M(K+(0)pi+pi-)<2 GeV/c(2).

Study of the suppressed decays B- -->[K+pi-](D)K- and B- -->[K+pi-]Dpi-

We report a study of the suppressed decays B--->[K(+)pi(-)](D)K- and B--->[K(+)pi(-)](D)pi(-), where [K(+)pi(-)](D) indicates that the K+pi(-) pair originates from a neutral D meson. These decay modes are sensitive to the unitarity triangle angle varphi(3). We use a data sample containing 275 x 10(6) BB pairs recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. The signal for B--->[K(+)pi(-)](D)K- is not statistically significant, and we set a limit r(B)<0.27 at 90% confidence level, where r(B) is the magnitude of the ratio of amplitudes |A(B--->D 0K-)/A(B--->D0K-)|. We observe a signal with 6.4sigma statistical significance in the related mode, B--->[K(+)pi(-)](D)pi(-).