Showing papers by "Ascelin Gordon published in 2004"
TL;DR: In this article, the authors report results of a study of charmless B meson decays to three-body Kππ, KKππ and KKK final states.
Abstract: We report results of a study of charmless B meson decays to three-body Kππ, KKπ and KKK final states. Measurements of branching fractions for B decays to K=+(0)π+π-, K +K+K-, K0K+K-, K+Ks 0Ks 0 and K s 0Ks 0Ks 0 final states are presented. The decays B0→K0K +K-, B+→K+Ks 0Ks 0 and B0→Ks 0Ks 0Ks 0 are observed for the first time. We also report evidence for B+→K +K-π+ decay. For the three-body final states K0K+π-, Ks 0K s 0π+, K+K+π - and K-π+π+, 90% confidence level upper limits are reported. Finally, we discuss the possibility of using the three-body B0→Ks 0K+K - decay for CP violation studies. The results are obtained with a 78 fb-1 data sample collected at the Y(4S) resonance by the Belle detector operating at the KEKB asymmetric energy e+e- collider. © 2004 The American Physical Society.
59 citations
TL;DR: In this paper, the authors reported improved measurements of branching fractions for $B\bar{B}$ pairs collected at the UPSilon (4S) resonance with the Belle detector at the KEKB $e^+e^-$ storage ring.
Abstract: We report improved measurements of branching fractions for $B\to K\pi$, $\pi^+\pi^-$, $\pi^+\pi^0$ and $K\bar{K}$ decays based on a data sample of 85.0 million $B\bar{B}$ pairs collected at the $\Upsilon (4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ storage ring. This data sample is almost three times larger than the sample previously used. We observe clear signals for $B\to K\pi$, $\pi^+\pi^-$ and $\pi^+\pi^0$ decays and set upper limits on $B\to K\bar{K}$ decays. The results can be used to give model-dependent constraints on the CKM angle $\phi_3$, as well as limits on the hadronic uncertainty in the time-dependent analysis of the angle $\phi_2$.
24 citations
TL;DR: In this article, the first evidence of the decay B0 --> rho0 pi0 was presented, using 140fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e+e-collider.
Abstract: We present the first evidence of the decay B0 --> rho0 pi0, using 140fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e+e- collider. We detect a signal with a significance of 3.5 standard deviations, and measure the branching fraction to be Br(B0 ->- rho0 pi0) = (5.1 +/- 1.6(stat) +/- 0.9(syst))*10^-6.
6 citations
11 Dec 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a massive mask made of tantalum and tungsten was placed on each side of the central section of the Belle detector to reduce the beam background that could accompany the reduction of the beampipe radius.
Abstract: We have upgraded the beampipe and the silicon vertex tracker of the Belle detector for increased luminosity and to achieve better vertex resolution. The radius of the beampipe was reduced from 2 to 1.5 cm to achieve better vertex resolution. In order to reduce the beam background that could accompany the reduction of the beampipe radius, a massive mask made of tantalum and tungsten was placed on each side of the central section. The total weight of them is 40 kg. The maximum radiation dose of the silicon tracker is measured about 80 krad/yr. This is lower than the dose of 100 krad per year with the previous beampipe even though the beampipe radius is smaller. The beampipe is designed to minimize heating, and enough cooling power is provided by the liquid cooling.
3 citations
Austrian Academy of Sciences1, Niigata University2, Tohoku University3, University of Tokyo4, University of Tsukuba5, University of Sydney6, National Taiwan University7, Princeton University8, University of Melbourne9, Osaka University10, Tokyo Institute of Technology11, Polish Academy of Sciences12, Kanagawa University13, University of Toronto14
11 Dec 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a major upgrade of the Silicon Vertex Detector (SVD 2.0) of the Belle experiment at the KEKB factory was installed along with new front-end and back-end electronics systems during the summer shutdown period in 2003 to cope with higher particle rates, improve the track resolution and meet the increasing requirements of radiation tolerance.
Abstract: A major upgrade of the Silicon Vertex Detector (SVD 2.0) of the Belle experiment at the KEKB factory was installed along with new front-end and back-end electronics systems during the summer shutdown period in 2003 to cope with higher particle rates, improve the track resolution and meet the increasing requirements of radiation tolerance. The SVD 2.0 detector modules are read out by VA1TA chips which provide “fast or” (hit) signals that are combined by the back-end FADCTF modules to coarse, but immediate level 0 track trigger signals at rates of several tens of a kHz. Moreover, the digitized detector signals are compared to threshold lookup tables in the FADCTFs to pass on hit information on a single strip basis to the subsequent level 1.5 trigger system, which reduces the rate below the kHz range. Both FADCTF and level 1.5 electronics make use of parallel real-time processing in Field Programmable Gate Arrays (FPGAs), while further data acquisition and event building is done by PC farms running Linux. The new readout system hardware is described and the first results obtained with cosmics are shown.
3 citations
Niigata University1, Tohoku University2, University of Tokyo3, University of Tsukuba4, University of Sydney5, National Taiwan University6, Princeton University7, University of Melbourne8, Osaka University9, Tokyo Institute of Technology10, Polish Academy of Sciences11, Kanagawa University12, University of Toronto13
11 Dec 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: A new silicon vertex detector for the BELLE experiment was installed and its operation has started successfully at the high-luminosity asymmetric energy e + e - collider KEKB in October 2003 as mentioned in this paper.
Abstract: A new silicon vertex detector for the BELLE experiment was installed and its operation has started successfully at the high-luminosity asymmetric energy e + e - collider KEKB in October 2003. This vertex detector provides a larger polar angle acceptance, a more precise vertex resolution and a better radiation tolerance than the previous one. The obtained performances indicate that the SVD2 works reliably as expected. Moreover, a prospective simulation study shows that the SVD2 should work under the coming higher background conditions.
2 citations