Masahiko Iwasaki

A new data acquisition system for the RIKEN-RAL μCF experiment

Abstract A new data acquisition system has been installed for a muon catalyzed fusion (μCF) experiment at the RIKEN-RAL Muon Facility. Detector signals are digitized in a CAMAC-based system and accumulated by a CAMAC one board computer with MC68030 CPU (Kineties K3976-Z1A). The accumulated data are transferred to a workstation (DEC Alpha-station 200) through a SCSI crate controller (Kinetics 3929-Z1B). On-line and off-line data analyses are performed on the workstation with the PAW++ package developed at CERN [1]. This DAQ system is easy to use and highly flexible so that it could fit any general application for CAMAC data acquisition.

Search for CP Violation in the Decays D{sub (s)}{sup +{yields}}K{sub S}{sup 0{pi}+} and D{sub (s)}{sup +{yields}}K{sub S}{sup 0}K{sup +}

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

Search for B{sup 0{yields}}K*{sup 0}K*{sup 0}, B{sup 0{yields}}K*{sup 0}K*{sup 0} and B{sup 0{yields}}K{sup +{pi}-}K{sup {+-}{pi}{+-}}decays

We report a search for the decays B-0 -> K*(0)(K) over bar*(0) and B-0 -> K*K-0*(0) . We also measure other charmless decay modes with K+ pi K--(-)pi(+) and K+pi K--(+)pi(-) final states. The results are obtained from a data sample containing 657 x 10(6) B (B) over bar pairs collected with the Belle detector at the KEKB asymmetric- energy e(+)e(-) collider. We set upper limits on the branching fractions for B-0 -> K*(0)(K) over bar*(0) and B-0 -> K*K-0*(0) of 0: 81 x 10(-6) and 0.20 x 10(-6), respectively, at the 90% confidence level.We report a search for the decays B{sup 0{yields}}K*{sup 0}K*{sup 0} and B{sup 0{yields}}K*{sup 0}K*{sup 0}. We also measure other charmless decay modes with K{sup +{pi}-}K{sup -{pi}+} and K{sup +{pi}-}K{sup +{pi}-} final states. The results are obtained from a data sample containing 657x10{sup 6} BB pairs collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. We set upper limits on the branching fractions for B{sup 0{yields}}K*{sup 0}K*{sup 0} and B{sup 0{yields}}K*{sup 0}K*{sup 0} of 0.81x10{sup -6} and 0.20x10{sup -6}, respectively, at the 90% confidence level.

Measurement of the branching fractions for B{sup 0{yields}}D{sub s}*{sup +{pi}-} and B{sup 0{yields}}D{sub s}*{sup -}K{sup +} decays

We present a study of B{sup 0{yields}}D{sub s}*{sup +{pi}-} and B{sup 0{yields}}D{sub s}*{sup -}K{sup +} decays based on a sample of 657x10{sup 6} BB events collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. We measure the branching fractions to be B(B{sup 0{yields}}D{sub s}*{sup +{pi}-})=(1.75{+-}0.34(stat){+-}0.17(syst){+-}0.11(B))x10{sup -5} and B(B{sup 0{yields}}D{sub s}*{sup -}K{sup +})=(2.02{+-}0.33(stat){+-}0.18(syst){+-}0.13(B))x10{sup -5}, with significances of 6.1 and 8.0 standard deviations, respectively. The first uncertainty is statistical, the second is due to the experimental systematics, and the third is from uncertainties in the D{sub s}{sup +} decay branching fractions. From our measurements, we obtain the most precise determination so far of R{sub D*{pi},} where R{sub D*{pi}}is the ratio between amplitudes of the doubly Cabibbo-suppressed decay B{sup 0{yields}}D*{sup +{pi}-} and the Cabibbo-favored B{sup 0{yields}}D*{sup -{pi}+} decay.We present a study of B0→Ds*+π- and B0→Ds*-K+ decays based on a sample of 657×106 BB events collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure the branching fractions to be B(B0→Ds*+π-)=(1.75±0.34(stat)±0.17(syst) ±0.11(B))×10-5 and B(B0→Ds*-K +)=(2.02±0.33(stat)±0.18(syst)±0.13(B)) ×10-5, with significances of 6.1 and 8.0 standard deviations, respectively. The first uncertainty is statistical, the second is due to the experimental systematics, and the third is from uncertainties in the Ds+ decay branching fractions. From our measurements, we obtain the most precise determination so far of RD*π, where RD*π is the ratio between amplitudes of the doubly Cabibbo-suppressed decay B0→D*+π- and the Cabibbo-favored B0→D*-π+ decay.

Observation of the Doubly Cabibbo-Suppressed Decay D{sub s}{sup +}{yields}K{sup +}K{sup +}{pi}{sup -}

We report the first observation of the doubly Cabibbo-suppressed decay D{sub s}{sup +}{yields}K{sup +}K{sup +}{pi}{sup -} using 605 fb{sup -1} of data collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. The branching ratio with respect to its Cabibbo-favored counterpart B(D{sub s}{sup +}{yields}K{sup +}K{sup +}{pi}{sup -})/B(D{sub s}{sup +}{yields}K{sup +}K{sup -}{pi}{sup +}) is (0.229{+-}0.028{+-}0.012)%, where the first uncertainty is statistical and the second is systematic. We also report a significantly improved measurement of the doubly Cabibbo-suppressed decay D{sup +}{yields}K{sup +}{pi}{sup +}{pi}{sup -}, with a branching ratio B(D{sup +}{yields}K{sup +}{pi}{sup +}{pi}{sup -})/B(D{sup +}{yields}K{sup -}{pi}{sup +}{pi}{sup +})=(0.569{+-}0.018{+-}0.014)%.

Measurement of the e{sup +}e{sup -}{yields}D{sup 0}D*{sup -}{pi}{sup +} cross section using initial-state radiation

We report measurements of the exclusive cross section for e{sup +}e{sup -}{yields}D{sup 0}D*{sup -}{pi}{sup +} as a function of center-of-mass energy from the D{sup 0}D*{sup -}{pi}{sup +} threshold to 5.2 GeV with initial-state radiation. No evidence is found for Y(4260){yields}D{sup 0}D*{sup -}{pi}{sup +} decays. The analysis is based on a data sample collected with the Belle detector at or near a center-of-mass energy of 10.58 GeV with an integrated luminosity of 695 fb{sup -1} at the KEKB asymmetric-energy e{sup +}e{sup -} collider.

Measurements of charmless hadronic b{yields}s penguin decays in the {pi}{sup +}{pi}{sup -}K{sup +}{pi}{sup -} final state and first observation of B{sup 0}{yields}{rho}{sup 0}K{sup +}{pi}{sup -}

We report measurements of charmless hadronic B{sup 0} decays into the {pi}{sup +}{pi}{sup -}K{sup +}{pi}{sup -} final state. The analysis uses a sample of 657x10{sup 6} BB pairs collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider at the resonance. The decay B{sup 0}{yields}{rho}{sup 0}K{sup +}{pi}{sup -} is observed for the first time; the significance is 5.0{sigma} and the corresponding partial branching fraction for M{sub K{pi}} is an element of (0.75,1.20) GeV/c{sup 2} is [2.8{+-}0.5(stat){+-}0.5(syst)]x10{sup -6}. We also obtain the first evidence for B{sup 0}{yields}f{sub 0}(980)K{sup +}{pi}{sup -} with 3.5{sigma} significance and for B{sup 0}{yields}{pi}{sup +}{pi}{sup -}K*{sup 0} with 4.5{sigma} significance. For the two-body decays B{sup 0}{yields}{rho}{sup 0}K*{sup 0} and B{sup 0}{yields}f{sub 0}(980)K*{sup 0}, the significances are 2.7{sigma} and 2.5{sigma}, respectively, and the upper limits on the branching fractions are 3.4x10{sup -6} and 2.2x10{sup -6} at 90% confidence level.We report measurements of charmless hadronic B0 decays into the π+π-K+π- final state. The analysis uses a sample of 657×106 BB pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at the resonance. The decay B0→ρ0K+π- is observed for the first time; the significance is 5.0σ and the corresponding partial branching fraction for MKπ(0.75,1.20)GeV/c2 is [2.8±0.5(stat) ±0.5(syst)]×10-6. We also obtain the first evidence for B0→f0(980)K+π- with 3.5σ significance and for B0→π+π- K*0 with 4.5σ significance. For the two-body decays B0→ρ0K*0 and B0→f0(980)K*0, the significances are 2.7σ and 2.5σ, respectively, and the upper limits on the branching fractions are 3.4×10-6 and 2.2×10-6 at 90% confidence level.

Measurement of D{sup +}{yields}K{sub S}{sup 0}K{sup +} and D{sub s}{sup +}{yields}K{sub S}{sup 0}{pi}{sup +} branching ratios

We report an improved measurement of D{sup +}{yields}K{sub S}{sup 0}K{sup +} and D{sub s}{sup +}{yields}K{sub S}{sup 0}{pi}{sup +} branching ratios using 605 fb{sup -1} of data collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. The measured branching ratios with respect to the Cabibbo-favored modes are B(D{sup +}{yields}K{sub S}{sup 0}K{sup +})/B(D{sup +}{yields}K{sub S}{sup 0}{pi}{sup +})=0.1899{+-}0.0011{+-}0.0022 and B(D{sub s}{sup +}{yields}K{sub S}{sup 0}{pi}{sup +})/B(D{sub s}{sup +}{yields}K{sub S}{sup 0}K{sup +})=0.0803{+-}0.0024{+-}0.0019 where the first uncertainties are statistical and the second are systematic.

Measurement of B{yields}D{sub s}{sup (*)}K{pi} branching fractions

We report a measurement of the exclusive

Observation of the {phi}(1680) and the Y(2175) in e{sup +}e{sup -}{yields}{phi}{pi}{sup +}{pi}{sup -}

B^+