Measurement of the CP-violation parameter sin2φ1 with a new tagging method at the Υ(5S) resonance

We report a measurement of the CP-violation parameter sin2φ1 at the Υ(5S) resonance using a new tagging method, called "B-π tagging." In Υ(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/ψK(S)(0) CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B-π(+) and B-π(-) tagged J/ψK(S)(0) yields, we determine sin2φ1=0.57±0.58(stat)±0.06(syst). The results are based on 121 fb(-1) of data recorded by the Belle detector at the KEKB e(+)e(-) collider.

Observation of two charged bottomoniumlike resonances in Υ(5S) decays

We report the observation of two narrow structures in the mass spectra of the π(±)Υ(nS) (n=1, 2, 3) and π(±)h(b)(mP) (m=1, 2) pairs that are produced in association with a single charged pion in Υ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M(1)=(10,607.2±2.0)  MeV/c2, Γ(1)=(18.4±2.4)  MeV, and M(2)=(10,652.2±1.5)  MeV/c2, Γ(2)=(11.5±2.2)  MeV. The results are obtained with a 121.4  fb(-1) data sample collected with the Belle detector in the vicinity of the Υ(5S) resonance at the KEKB asymmetric-energy e+ e- collider.

Search for CP violation in D± meson decays to ϕπ±

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D(±)→K(+)K(-)π(±) and the Cabibbo-favored decays D(s)(±)→K(+)K(-)π(±) in the K(+)K(-) mass region of the ϕ resonance. Using 955  fb(-1) of data collected with the Belle detector, we obtain A(CP)(D+→ϕπ+)=(+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5. We find no evidence for direct CP violation.

Evidence for direct CP violation in B±→ηh± and observation of B0→ηK0

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

First observation of the P-wave spin-singlet bottomonium states hb(1P) and hb(2P)

We report the first observations of the spin-singlet bottomonium states h(b)(1P) and h(b)(2P). The states are produced in the reaction e(+)e(-)→h(b)(nP)π(+)π(-) using a 121.4 fb(-1) data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We determine M[h(b)(1P)]=(9898.2(-1.0-1.1)(+1.1+1.0)) MeV/c(2) and M[h(b)(2P)]=(10,259.8±0.6(-1.0)(+1.4)) MeV/c(2), which correspond to P-wave hyperfine splittings ΔM(HF)=(+1.7±1.5) and (+0.5(-1.2)(+1.6)) MeV/c(2), respectively. The significances of the h(b)(1P) and h(b)(2P) are 5.5σ and 11.2σ, respectively. We find that the production of the h(b)(1P) and h(b)(2P) is not suppressed relative to the production of the Υ(1S), Υ(2S), and Υ(3S).

Observation of D+ → K(+)η(') and search for CP violation in D+ → π(+)η(') decays

We report the first observation of the doubly Cabibbo-suppressed decays D(+)→K(+)η((')) using a 791 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed D(+)→π(+)η((')) decays are B(D(+)→K(+)η)/B(D(+)→π(+)η)=(3.06±0.43±0.14)% and B(D(+)→K(+)η')/B(D(+)→π(+)η')=(3.77±0.39±0.10)%. From these, we find that the relative final-state phase difference between the tree and annihilation amplitudes in D(+) decays, δ(TA), is (72±9)° or (288±9)°. We also report the most precise measurements of CP asymmetries to date: A(CP)(D(+)→π(+)η)=(+1.74±1.13±0.19)% and A(CP)(D(+)→π(+)η')=(-0.12±1.12±0.17)%.

Search for CP violation in τ±→K(S)0π±ντ decays at Belle

We report on a search for CP violation in τ(±)→K(S)(0)π(±)ν(τ) decays using a data sample of 699 fb(-1) collected by the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K(S)(0)π(±) system and found to be compatible with zero with a precision of O(10(-3)) in each mass bin. Limits for the CP violation parameter Im(η(S)) are given at the 90% confidence level. These limits are |Im(η(S))| < 0.026 or better, depending on the parametrization used to describe the hadronic form factors, and improve upon previous limits by 1 order of magnitude.

Observation of X(3872)→J/ψγ and search for X(3872)→ψ'γ in B decays

We report a study of B→(J/ψγ)K and B→(ψ'γ)K decay modes using 772×10⁶ B ̅B events collected at the Υ(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. We observe X(3872)→J/ψγ and report the first evidence for χ(c2)→J/ψγ in B→(X_{c ̅cγ)K decays, while in a search for X(3872)→ψ'γ no significant signal is found. We measure the branching fractions, B(B(±)→X(3872)K(±))B(X(3872)→J/ψγ)=(1.78(-0.44)(+0.48)±0.12)×10(-6), B(B(±)→χ(c2)K(±))=(1.11(-0.34)(+0.36)±0.09)×10(-5), B(B(±)→X(3872)K(±))B(X(3872)→ψ'γ)<3.45×10⁶ (upper limit at 90% C.L.), and also provide upper limits for other searches.

Observation of transverse polarization asymmetries of charged pion pairs in e+e- annihilation near √s = 10.58 GeV

The interference fragmentation function translates the fragmentation of a quark with a transverse projection of the spin into an azimuthal asymmetry of two final-state hadrons. In e(+)e(-) annihilation the product of two interference fragmentation functions is measured. We report nonzero asymmetries for pairs of charge-ordered π(+)π(-) pairs, which indicate a significant interference fragmentation function in this channel. The results are obtained from a 672 fb(-1) data sample that contains 711 × 10(6) π(+)π(-) pairs and was collected at and near the Υ(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider.

Evidence for the suppressed decay B(-)→DK(-), D→K(+)π(-)

The suppressed decay chain B(-)→DK(-), D→K(+)π(-), where D indicates a D(¯)(0) or D(0) state, provides important information on the CP-violating angle ϕ(3). We measure the ratio R(DK) of the decay rates to the favored mode B(-)→DK(-), D→K(-)π(+) to be R(DK)=[1.63(-0.41)(+0.44)(stat)(-0.13)(+0.07)(syst)]×10(-2), which indicates the first evidence of the signal with a significance of 4.1σ. We also measure the asymmetry A(DK) between the charge-conjugate decays to be A(DK)=-0.39(-0.28)(+0.26)(stat)(-0.03)(+0.04)(syst). The results are based on the full 772×10(6) BB(¯) pair data sample collected at the Υ(4S) resonance with the Belle detector.

Search for CP violation in the decays D(0)→K(S)(0)P(0)

We have searched for CP violation in the decays D(0)→K(S)(0)P(0) where P(0) denotes a neutral pseudoscalar meson that is either a π(0), η, or η' using KEKB asymmetric-energy e(+)e(-) collision data corresponding to an integrated luminosity of 791 fb(-1) collected with the Belle detector. No evidence of significant CP violation is observed. We report the most precise CP asymmetry measurement in the decay D(0)→K(S)(0)π(0) to date: A(CP)(D(0)→K(S)(0)π(0))=(-0.28±0.19±0.10)%. We also report the first measurements of CP asymmetries in the decays D(0)→K(S)(0)η and D(0)→K(S)(0)η': A(CP)(D(0)→K(S)(0)η)=(+0.54±0.51±0.16)% and A(CP)(D(0)→K(S)(0)η')=(+0.98±0.67±0.14)%, respectively.

Observation of B(s)⁰→J/ψf₀(980) and evidence for B(s)⁰→J/ψf₀(1370)

We report the observation of B(s)⁰→J/ψf₀(980) and evidence for B(s)⁰→J/ψf₀(1370), which are CP eigenstate decay modes. These results are obtained from 121.4 fb⁻¹ of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e(+)e⁻ collider. We measure the branching fractions B(B(s)⁰→J/ψf₀(980); f₀(980)→π(+)π⁻)=(1.16(-0.19)(+0.31)(stat)(-0.17)(+0.15)(syst)(-0.18)(+0.26)(N(B(s)((*))B(s)((*)))))×10⁻⁴ with a significance of 8.4σ, and B(B(s)⁰→J/ψf₀(1370); f₀(1370)→π(+)π⁻)=(0.34(-0.14)(+0.11)(stat)(-0.02)(+0.03)(syst)(-0.05)(+0.08)(N(B(s)((*))B(s)((*)))))×10⁻⁴ with a significance of 4.2σ. The last error listed is due to uncertainty in the number of produced B(s)((*))B(s)((*)) pairs.

Differences between Sputtering Methods in The Formation of Amorphous Magnetic Alloy Films

Fe-Si, Co-Ta and Co-Zr amorphous films have been deposited by using various sputtering methods (conventional rf diode sputtering, rf triode sputtering, dc Targets Facing type sputtering (dc TF sputtering) and dual ion beam sputtering (DIB sputtering)). The lower limit of the Si and Ta content to form amorphous Fe-Si and Co-Ta films changes significantly with the sputtering method. These differences between the sputtering methods are mainly caused by the differences in the plasma potential which affects the amount of ion bombardment to the film surface during sputtering,and the minimum content of Si or Ta to obtain amorphous films decreases as the plasma potential increases. These results indicate that the ion bombardment suppresses the growth of crystallites and promotes the formation of the films with amorphous structures. This is confirmed by the deposition of Co-Ta and Co-Zr amorphous films under the condition of various amount of ion bombardment by using a DIB sputtering system.

Observation of B(s)(0) → D(s)(*)+ D(s)(*)- using e+ e- collisions and a determination of the B(s)-B(s) width difference ΔΓ(s)

We have made the first observation of B(s)(0)→D(s)(*)+ D(s)(*)- decays using 23.6  fb(-1) of data recorded by the Belle experiment running on the Υ(5S) resonance. The branching fractions are measured to be B(B(s)(0)→D(s)+ D(s)-)=(1.03(-0.32-0.25)(+0.39+0.26))%, B(B(s)(0)→D(s)(*±) D(s)(∓))=(2.75(-0.71)(+0.83)±0.69)%, and B(B(s)(0)→D(s)*+ D(s)*-)=(3.08(-1.04-0.86)(+1.22+0.85))%; the sum is B[B(s)(0)→D(s)(*)+ D(s)(*)-]=(6.85(-1.30-1.80)(+1.53+1.79))%. Assuming B(s)(0)→D(s)(*)+ D(s)(*)- saturates decays to CP-even final states, the branching fraction determines the ratio ΔΓ(s)/cosφ, where ΔΓ(s) is the difference in widths between the two B(s)-B(s) mass eigenstates, and φ is a CP-violating weak phase. Taking CP violation to be negligibly small, we obtain ΔΓ(s)/Γ(s)=0.147(-0.030)(+0.036)(stat)(-0.041)(+0.042)(syst), where Γ(s) is the mean decay width.

First measurement of inclusive B→Xsη decays

We report a first measurement of inclusive B→Xsη decays, where Xs is a charmless state with unit strangeness. The measurement is based on a pseudoinclusive reconstruction technique and uses a sample of 657×10(6)BB pairs accumulated with the Belle detector at the KEKB e+e- collider. For MXs < 2.6 GeV/c2, we measure a branching fraction of [26.1±3.0(stat)-2.1+1.9(syst)-7.1+4.0(model)]×10(-5) and a direct CP asymmetry of ACP=-0.13±0.04-0.03+0.02. Over half of the signal occurs in the range MXs > 1.8 GeV/c2.

Search for a low mass particle decaying into μ+ μ- in B0 → K*0 X and B0 → ρ0 X at Belle

We search for dimuon decays of a low mass particle in the decays B0→K*0 X and B0→ρ0 X using a data sample of 657×10(6)BB events collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We find no evidence for such a particle in the mass range from 212  MeV/c2 to 300  MeV/c2 for lifetimes below 10(-12)  s, and set upper limits on its branching fractions. In particular, we search for a particle with a mass of 214.3  MeV/c2 reported by the HyperCP experiment, and obtain upper limits on the products B(B0→K*0 X)×B(X→μ+ μ- )<2.26(2.27)×10(-8) and B(B0→ρ0 X)×B(X→μ+ μ-)<1.73(1.73)×10(-8) at 90% C.L. for a scalar (vector) X particle.

Observation of B(s)(0) → D(s)(*-) π+ and B(s)(0) → D(s)(*-) ρ+ and measurement of the B(s)(0) → D(s)(*-) ρ+ longitudinal polarization fraction

First observations of the B(s)(0) → D(s)(*-) π+, B(s)(0) → D(s)(-) ρ+ and B(s)(0) → D(s)(*-) ρ+ decays are reported together with measurements of their branching fractions: B(B(s)(0) → D(s)(*-) π+) = [2.4(-0.4)(+0.5)(stat) ± 0.3(syst) ± 0.4(f(s))]×10(-3), B(B(s)(0) → D(s)(-) ρ+) = [8.5(-1.2)(+1.3)(stat) ± 1.1(syst) ± 1.3(f(s))]×10(-3) and B(B(s)(0) → D(s)(*-) ρ+) = [11.9(-2.0)(+2.2)(stat) ± 1.7(syst) ± 1.8(f(s))]×10(-3) (f(s) = N(B(s)(*) B(s)(*))/N(bb)). From helicity-angle distributions, we measured the longitudinal polarization fraction in B(s)(0) → D(s)(*-) ρ+ decays to be f(L)(B(s)(0) → D(s)(*-) ρ+) = 1.05(-0.10)(+0.08)(stat)(-0.04)(+0.03)(syst). These results are based on a 23.6  fb(-1) data sample collected at the Υ(5S) resonance with the Belle detector at the KEKB e+ e- collider.

Search for CP violation in the decays D(s)+ --> KS0pi+ and D(s)+ --> KS0K+

We have searched for CP violation in the charmed meson decays D((s))(+) --> K(S)(0)pi(+) and D((s))(+) --> K(S)(0)K(+) using 673 fb(-1) of data collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. No evidence for CP violation is observed. We report the most sensitive CP asymmetry measurements to date for these decays: A(CP)(D(+)-->K(S)(0)pi(+)) = (-0.71 +/- 0.19 +/- 0.20)%, A(CP)(D(s)(+) --> K(S)(0)pi(+)) = (+5.45 +/- 2.50 +/- 0.33)%, A(CP)(D(+) --> K(S)(0)K(+)) = (-0.16 +/- 0.58 +/- 0.25)%, and A(CP)(D(s)(+) --> K(S)(0)K(+)) = (+0.12 +/- 0.36 +/- 0.22)%, where the first uncertainties are statistical and the second are systematic.

Evidence for a new resonance and search for the Y(4140) in the gammagamma-->phiJ/psi process

The process gammagamma-->phiJ/psi is measured using a data sample of 825 fb{-1} collected with the Belle detector. A narrow peak of 8.8{-3.2}{+4.2} events, with a significance of 3.2 standard deviations including systematic uncertainty, is observed. The mass and natural width of the structure [named X(4350)] are measured to be [4350.6{-5.1}{+4.6}(stat)+/-0.7(syst)] MeV/c{2} and [13{-9}{+18}(stat)+/-4(syst)] MeV, respectively. The product of its two-photon decay width and branching fraction to phiJ/psi is [6.7{-2.4}{+3.2}(stat)+/-1.1(syst)] eV for J{P}=0{+}, or [1.5{-0.6}{+0.7}(stat)+/-0.3(syst)] eV for J{P}=2{+}. No signal for the Y(4140)-->phiJ/psi structure reported by the CDF Collaboration in B-->K{+}phiJ/psi decays is observed, and limits of Gamma_{gammagamma}(Y(4140))B(Y(4140)-->phiJ/psi)<41 eV for J{P}=0;{+} or <6.0 eV for J{P}=2{+} are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a D{s}{*+}D{s}{*-} molecule.

Observation of a charmoniumlike enhancement in the gammagamma-->omega(J)/psi process

We report the results of a search for a charmoniumlike state produced in the process gammagamma-->omegaJ/psi in the 3.9-4.2 GeV/c{2} mass region. We observe a significant enhancement, which is well described by a resonant shape with mass M=(3915+/-3+/-2) MeV/c{2} and total width Gamma=(17+/-10+/-3) MeV. This enhancement may be related to one or more of the three charmoniumlike states so far reported in the 3.90-3.95 GeV/c{2} mass region.

Measurement of |V{ub}| from inclusive charmless semileptonic B decays

We present the partial branching fraction for inclusive charmless semileptonic B decays and the corresponding value of the Cabibbo-Kobayashi-Maskawa matrix element |V{ub}|, using a multivariate analysis method to access approximately 90% of the B-->X{u}lnu phase space. This approach dramatically reduces the theoretical uncertainties from the b-quark mass and nonperturbative QCD compared to all previous inclusive measurements. The results are based on a sample of 657x10{6} BB[over ] pairs collected with the Belle detector. We find that DeltaB(B-->X{u}lnu;p(l){*B}>1.0 GeV/c)=1.963x(1+/-0.088{stat}+/-0.081{syst})x10{-3}. Corresponding values of |V{ub}| are extracted using several theoretical calculations.