H. Ha

Upgrade of the Level 1 Global Trigger System in the Belle Experiment

In this paper, we describe design and development of the new global decision logic units for the Belle detector at the KEK B-factory. The new units consist of two identical 9U VME modules which are designed using the programmable logic techniques. Each module has an inexpensive programmable logic device that has high density input and output lines. Performance tests of these new modules and existing system are compared and showed good results. Utilizing the nature of the logic device on the board, we also examine possibility of the implementation of an artificial neural network algorithm to the new trigger board for a more efficient 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.

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 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.