666 research outputs found
Search for double charmonium decays of the P-wave spin-triplet bottomonium states
Using a sample of 158 million events collected with the Belle
detector, we search for the first time for double charmonium decays of the
-wave spin-triplet bottomonium states (,
\chi_{bJ} \to \jpsi \jpsi, \jpsi \psp, \psp \psp for J=0, 1, and 2). No
significant signal is observed in the double charmonium mass
spectra, and we obtain the following upper limits, \BR(\chi_{bJ} \to \jpsi
\jpsi)<7.1\times 10^{-5}, , ,
\BR(\chi_{bJ} \to \jpsi \psp)<1.2\times 10^{-4}, ,
, \BR(\chi_{bJ} \to \psp \psp)<3.1\times 10^{-5},
, for J=0, 1, and 2, respectively, at
the 90% confidence level. These limits are significantly lower than the central
values (with uncertainties of 50% to 70%) predicted using the light cone
formalism but are consistent with calculations using the NRQCD factorization
approach.Comment: 7 pages, 4 figures, 1 tabl
Bounds on the width, mass difference and other properties of X(3872) --> pi+pi-J/psi decays
We present results from a study of X(3872) --> pi+pi- J/psi decays produced
via exclusive B--> K X(3872) decays. We determine the mass to be M_X(3872)=
(3871.84\pm 0.27 (stat)\pm 0.19 (syst)) MeV, a 90% CL upper limit on the
natural width of Gamma_X(3872)
K+X(3872))xBf(X(3872)-->pi+pi-J/psi)=(8.61 \pm 0.82(stat) \pm 0.52 (syst))
x10^{-6}, and a ratio of branching fractions Bf(B0--> K0 X(3872))/BF(B+--> K+
X(3872))=0.50\pm 0.14(stat)\pm0.04(syst). The difference in mass between the
X(3872)-->pi+pi-J/psi signals in B+ and B0 decays is Delta M_{X(3872)= (-0.69
\pm 0.97 (stat)} \pm 0.19 (syst)) MeV. A search for a charged partner of the
X(3872) in the decays Bbar0-->K- X+ or B+-->K0X+, X+-->pi+pi0 J/psi resulted in
upper limits on the product branching fractions for these processes that are
well below expectations for the case that the X(3872) is the neutral member of
an isospin triplet. In addition, we examine possible J^{PC} quantum number
assignments for the X(3872) based on comparisons of angular correlations
between final state particles in X(3872)-->pi+pi-J/psi decays with simulated
data for J^{PC} values of 1^{++} and 2^{-+}. We examine the influence of
rho-omega interference in the M(pi+pi-) spectrum. The analysis is based on a
711fb^{-1} data sample that contains 772 million BBbar meson pairs collected at
the Upsilon(4S) resonance in the Belle detector at the KEKB e+e- collider.Comment: 15 pages, 10 figures and 6 tables. Submitted to Physical Review
First Observation of Radiative B^0 -> \phi K^0 \gamma Decays and Measurements of Their Time-Dependent CP Violation
We report the first observation of the radiative decay B^0 -> \phi K^0 \gamma
using a data sample of 772 x 10^6 B B-bar pairs collected at the \Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e^+e^-
collider. We observe a signal of 37+/-8 events with a significance of 5.4
standard deviations including systematic uncertainties. The measured branching
fraction is , where the uncertainties are statistical and systematic, respectively.
We also report the first measurements of time-dependent CP violation
parameters: and . Furthermore, we measure , and find that the signal is concentrated in
the M_{\phi K} mass region near threshold.Comment: 6 pages, 3 figures, Modified version is to be published in PRD(RC
Observation of and search for in B decays
We report a study of and
decay modes using events collected at the
\Upsilon(4S)e^+ e^-X(3872) \to J/\psi \gamma\chi_{c2} \to J/\psi \gammaB\to (X_{c\bar{c}}\gamma) KX(3872) \to \psi' \gamma\mathcal{B}(B^{\pm} \to X(3872)
K^{\pm}) \mathcal{B}(X(3872) \to J/\psi\gamma)=(1.78^{+0.48}_{-0.44}\pm
0.12)\times 10^{-6}\mathcal{B} (B^{\pm} \to\chi_{c2} K^{\pm})=(1.11^{+0.36}_{-0.34} \pm 0.09) \times 10^{-5}\mathcal{B}(B^{\pm} \to
X(3872) K^{\pm}) \mathcal{B}(X(3872) \to \psi'\gamma)<3.45\times 10^{-6}$
(upper limit at 90% C.L.) and also provide upper limits for other searches.Comment: 6 pages, 3 figure
Observation of and Search for CP Violation in Decays
We report the first observation of the doubly Cabibbo-suppressed decays using a 791 fb data sample collected
with the Belle detector at the KEKB asymmetric-energy collider. The
ratio of the branching fractions of doubly Cabibbo-suppressed relative to
singly Cabibbo-suppressed decays are
= (3.06 0.43 0.14)% and = (3.77 0.39
0.10)%. From these, we find that the relative final-state phase difference
between the tree and annihilation amplitudes in decays, , is
(72 9) or (288 9). We also report the most precise
measurements of CP asymmetries to date: =
(+1.74 1.13 0.19)% and =
(0.12 1.12 0.17)%.Comment: 6 pages, 2 figures, 3 tables. Published in PR
Comparison of Efficacy of Cefoperazone/Sulbactam and Imipenem/Cilastatin for Treatment of Acinetobacter Bacteremia
Multiple antibiotic reisistance threatens successful treatment of Acinetobacter baumannii infections worldwide. Increasing interest in the well-known activity of sulbactam against the genus Acinetobacter has been aroused. The purpose of this study was to compare the outcomes for patients with Acinetobacter bacteremia treated with cefoperazone/sulbactam versus imipenem/cilastatin. Forty-seven patients with Acinetobacter baumannii bacteremia were analyzed through a retrospective review of their medical records for antibiotic therapy and clinical outcome. Thirty-five patients were treated with cefoperazone/sulbactam, and twelve patients with imipenem/cilastatin. The percentage of favorable response after 72 hours was not statistically different between cefoperazone/ sulbactam group and imipenem/ cilastatin group. The mortality rate was not statistically different, too. Cefoperazone/sulbactam was found to be as useful as imipenem/cilastatin for treating patients with Acinetobacter bacteremia
Search for charmonium and charmonium-like states in \Upsilon(2S) radiative decays
Using a sample of 158 million \Upsilon(2S) events collected with the Belle
detector, charmonium and charmonium-like states with even charge parity are
searched for in \Upsilon(2S) radiative decays. No significant \chi_{cJ} or
\eta_c signal is observed and the following upper limits at 90% confidence
level (C.L.) are obtained: BR(\Upsilon(2S)\to \gamma \chi_{c0})< 1.0 \times
10^{-4}, BR(\Upsilon(2S) \to \gamma \chi_{c1})<3.6 \times 10^{-6},
BR(\Upsilon(2S) \to \gamma \chi_{c2})<1.5 \times 10^{-5}, and BR(\Upsilon(2S)
\to \gamma \eta_c)< 2.7 \times 10^{-5}. No significant signal of any
charmonium-like state is observed, and we obtain the limits \BR(\Upsilon(2S)\to
\gamma X(3872))\times\BR(X(3872)\to\pi^+\pi^-J/\psi)< 0.8 \times 10^{-6},
BR(\Upsilon(2S) \to \gamma X(3872))\times BR(X(3872)\to\pi^+\pi^-\pi^0 J/\psi)<
2.4\times 10^{-6}, BR(\Upsilon(2S) \to \gamma X(3915))\times
BR(X(3915)\to\omega J/\psi)< 2.8\times 10^{-6}, BR(\Upsilon(2S) \to \gamma
Y(4140))\times BR(Y(4140)\to\phi J/\psi)) < 1.2\times 10^{-6}, and
BR(\Upsilon(2S) \to \gamma X(4350))\times BR(X(4350)\to\phi J/\psi))< 1.3\times
10^{-6} at 90% C.L.Comment: 7 pages, 6 figures, 1 tabl
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