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31.
32.
In this paper,we calculated the B →(J/ψ,ηc) K decays in the perturbative QCD(pQCD) factorization approach with the inclusion of the partial next-to-leading order(NLO) contributions. With the inclusion of the significant enhancement from the NLO vertex corrections,the NLO pQCD predictions for the branching ratios agree with the data within 2σ errors:Br(B0 → J/ψK0) = 5.2-+32..58×10-4,Br(B+ → J/ψK+) = 5.6-+32..79×10-4,Br(B0 →ηcK0) = 5.5-+22..30 × 10-4,Br(B+ →ηcK+) = 5.9-+22..51 × 10-4. 相似文献
33.
In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0(980)π^0, a0^+ (980)π^-, a0^-(980)π^+ and B^- → a0^0 (980)π^-, a0^- (980)π^0 by employing the perturbative QCD (pQCD) factorization approach at the leading order. We found that (a) the pQCD predictions for the branching ratios are around (0.4-2.8) × 10^-6, consistent with currently available experimental upper limits; (b) the CP asymmetries of B^0→ a0^0(980)π^0 and B^- → a0^- (980)π^0 decays can be large, about (70-80)% for α= 100°. 相似文献
34.
S.P. Avdeyev V.A. Karnaukhov W.D. Kuznetsov L.A. Petrov V.K. Rodionov A.S. Zubkevich H. Oeschler O.V. Bochkarev L.V. Chulkov E.A. Kuzmin A. Budzanovski W. Karcz M. Janicki E. Norbeck A.S. Botvina W.A. Friedman W. Nörenberg G. Papp 《The European Physical Journal A - Hadrons and Nuclei》1998,3(1):75-83
Multiple emission of intermediate-mass fragments has been studied for the collisions p + Au at 2.16, 3.6 and 8.1 GeV with
the FASA setup. The mean IMF multiplicities for events with at least one IMF are equal to 1.7, 1.9 and 2.1 (±0.2) respectively.
The multiplicity, charge distributions and kinetic energy spectra of IMF are described in the framework of a intranuclear
cascade model followed by the statistical multifragmentation model. However, between the two parts of the calculation the
excitation energies and the residual masses and charges are modified to take into account the losses during expansion. The
results support a scenario of true thermal multifragmentation of a hot and expanded target spectator.
Received: 15 December 1997 / Revised version: 24 April 1998 相似文献
35.
在具有伸缩子的QCD势模型中的重介子 总被引:1,自引:0,他引:1
从伸缩子–胶子有效耦合理论得到的重夸克–反夸克势模型出发,计算了重介子的自旋平均能谱及轻子衰变和辐射跃迁宽度,并与Cornell势模型所得到的相应结果作了比较.结果表明,新的重夸克势的计算结果与重介子的实验数据更好地符合,而且估计的伸缩子质量5?7MeV很好地位于有关伸缩子质量的其他理论途径所估计的范围之内. 相似文献
36.
Zhi-Qing Zhang Zhi-Lin Guan Yan-Chao Zhao Zi-Yu Zhang Zhi-Jie Sun Na Wang Xiao-Dong Ren 《中国物理C(英文版)》2023,47(1):013103-013103-9
We study the \begin{document}$ B_{c,u,d}\to X(3872)P $\end{document} ![]()
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decays in the perturbative QCD (PQCD) approach, involving the puzzling resonance \begin{document}$ X(3872) $\end{document} ![]()
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, where P represents a light pseudoscalar meson (K or π). Assuming \begin{document}$ X(3872) $\end{document} ![]()
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to be a \begin{document}$ 1^{++} $\end{document} ![]()
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charmonium state, we obtain the following results. (a) The branching ratios of the \begin{document}$ B^+_c\to X(3872)\pi^+ $\end{document} ![]()
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and \begin{document}$ B^+_c\to X(3872) K^+ $\end{document} ![]()
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decays are consistent with the results predicted by the covariant light-front approach within errors; however, they are larger than those given by the generalized factorization approach. (b) The branching ratio of the \begin{document}$ B^+\to X(3872)K^+ $\end{document} ![]()
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decay is predicted as \begin{document}$ (3.8^{+1.1}_{-1.0})\times10^{-4} $\end{document} ![]()
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, which is smaller than the previous PQCD calculation result but still slightly larger than the upper limits set by Belle and BaBar. Hence, we suggest that the\begin{document}$ B^{0,+}\to X(3872)K^{0,+} $\end{document} ![]()
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decays should be precisely measured by the LHCb and Belle II experiments to help probe the inner structure of \begin{document}$ X(3872) $\end{document} ![]()
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. (c) Compared with the \begin{document}$ B_{u,d}\to X(3872)K $\end{document} ![]()
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decays, the \begin{document}$ B_{u,d}\to X(3872)\pi $\end{document} ![]()
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decays have significantly smaller branching ratios, which drop to values as low as \begin{document}$ 10^{-6} $\end{document} ![]()
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. (d) The direct CP violations of these considered decays are small (\begin{document}$ 10^{-3}\sim 10^{-2} $\end{document} ![]()
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) because the penguin contributions are loop suppressed compared to the tree contributions. The mixing-induced CP violation of the \begin{document}$ B\to X(3872)K^0_S $\end{document} ![]()
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decay is highly consistent with the current world average value \begin{document}$ \sin2\beta=(69.9\pm1.7)$\end{document} ![]()
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%. Experimentally testing the results for the branching ratios and CP violations, including the implicit \begin{document}$S U(3)$\end{document} ![]()
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and isospin symmetries of these decays, helps probe the nature of \begin{document}$ X(3872) $\end{document} ![]()
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. 相似文献
37.
A multi-charged particle model with local U(1)μ-τ to explain muon g–2, flavor physics,and possible collider signature 下载免费PDF全文
We consider a model with multi-charged particles, including vector-like fermions, and a charged scalar under a local \begin{document}$ U(1)_{\mu - \tau} $\end{document} ![]()
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symmetry. We search for an allowed parameter region explaining muon anomalous magnetic moment (muon \begin{document}$ g-2 $\end{document} ![]()
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) and \begin{document}$ b \to s \ell^+ \ell^- $\end{document} ![]()
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anomalies, satisfying constraints from the lepton flavor violations, Z boson decays, meson anti-meson mixing, and collider experiments. Via numerical analysis, we explore the typical size of the muon \begin{document}$ g-2 $\end{document} ![]()
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and Wilson coefficients to explain the \begin{document}$ b \to s \ell^+ \ell^- $\end{document} ![]()
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anomalies in our model when all other experimental constraints are satisfied. Subsequently, we discuss the collider physics of the multicharged vectorlike fermions, considering a number of benchmark points in the allowed parameter space. 相似文献
38.
Methods for determining the heat content E
*/A of hot nuclei formed in energetic nuclear reactions are discussed. The primary factors involved in converting raw data into
thermal physics distributions include: 1) design of the detector array, 2) constraints imposed by the physics of the reaction
mechanism, and 3) assumptions involved in converting the filtered data into E
*/A. The two primary sources of uncertainty in the calorimetry are the elimination of nonequilibrium emissions from the event
components and accounting for the contribution of neutron emission to the excitation energy sum. 相似文献
39.
J. Arnold B. van den Brandt M. Daum M. Finger M. Finger Jr. J. Franz N. Goujon-Naef P. Hautle R. Hess A. Janata J.A. Konter H. Lacker C. Lechanoine-Leluc F. Lehar S. Mango D. Rapin E. Rössle R. Schirmaier P.A. Schmelzbach M. Schmidt H. Schmitt P. Sereni M. Slunecka A. Teglia B. Vuaridel 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):411-415
Abstact: The kinetic energy spectrum and the polarization of the PSI neutron beam produced in the reaction 12C(p,n)X at 0° with 590 MeV polarized protons were investigated. A strong energy dependence of the neutron beam polarization is
observed which was not expected at the time the neutron beam was built.
Received: 3 April 1998 相似文献
40.
Hee-tak Kim Jung-ki Park Kew-ho Lee 《Journal of Polymer Science.Polymer Physics》1995,33(11):1585-1591
The multiplet formation in calcium partially neutralized poly(acrylamidocaproic acid) was studied by using differential scanning calorimetry and Fourier transform infrared spectroscopy. At 20 mol % of neutralization of acid groups, the ionic groups started to aggregate to form multiplets. The hydrogen bonding of amide group was destroyed during multiplet formation due to the reduction of the motional freedom of the side chain. The extension of the short side chain started to be loosened at the neutralization of 44 mol %. In this state, the multiplets could be formed without severe side chain stretching due to the proximity of the ionic groups. It is expected that the more stable multiplet is formed with increasing the degree of neutralization. © 1995 John Wiley & Sons, Inc. 相似文献