共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhi-Gang Luo Xiao-Lin Chen Xiang Liu Shi-Lin Zhu 《The European Physical Journal C - Particles and Fields》2009,60(3):403-411
Stimulated by recent observations of the excited bottom–strange mesons B
s1 and B
s2*, we calculate the semileptonic decays
, which is relevant for the exploration of the potential of searching these semileptonic decays in experiment. 相似文献
2.
We reconsider the utility of the radiative decay B→γℓν with an energetic photon in the final state for determining parameters of the B-meson light-cone distribution amplitude. Including 1/m
b
power corrections and radiative corrections at next-to-leading logarithmic order, we perform an improved analysis of the
existing BABAR data. We find a provisional lower limit on the inverse moment of the B meson distribution amplitude, λ
B
, which, due to the inclusion of radiative and power corrections, is significantly lower than the previous result. More data
with large photon energy are, however, required to obtain reliable results, as should become available in the future from
SuperB factories. 相似文献
3.
Junfeng Sun Dongsheng Du Yueling Yang 《The European Physical Journal C - Particles and Fields》2009,60(1):107-117
The B
c
→J/ψ
π, η
c
π decays are studied with the perturbative QCD approach. It is found that the form factors
and
for the B
c
→J/ψ, η
c
transitions and the branching ratios are sensitive to the parameters ω, v, f
J/ψ
and
, where ω and v are the parameters of the charmonium wave functions for a Coulomb potential and the harmonic-oscillator potential, respectively,
and f
J/ψ
and
are the decay constants of the J/ψ and η
c
mesons, respectively. The large branching ratios and the clear signals of the final states make the B
c
→J/ψ
π, η
c
π decays the prospective channels for measurements at the hadron colliders. 相似文献
4.
采用基于第一性原理的赝势平面波方法系统地计算了LiBX2 (B= Ga, In; X= S,Se,Te) 晶体的光学性质与力学性质. 由禁带宽度推断出晶体抗激光损伤阈值的大小顺序为LiGaS2 > LiInS2 > LiGaSe2 > LiInSe2 > LiGaTe2 > LiInTe2. 六种晶体在常压下均满足机械力学稳定性要求, 且铟化合物可塑性及延展性强于镓化合物. 这些晶体的静态电介电常数 ε1(0)、静态折射率n(0)和双折射率Δn 理论计算值与实验值相符. LiGaS2, LiInS2, LiGaSe2, LiInSe2和LiGaTe2五种化合物双折射率较高, 并且它们的吸收谱与反射谱在中远红外区是透过的, 因此可推断出这五种化合物可以成为优异的中远红外非线性光学材料. 相似文献
5.
Ying Li Juan Hua Kwei-Chou Yang 《The European Physical Journal C - Particles and Fields》2011,71(10):1775
The implications of the family non-universal Z′ model in the B→K
1(1270,1400)ℓ
+
ℓ
−(ℓ=e ,μ ,τ) decays are explored, where the mass eigenstates K
1(1270, 1400) are the mixtures of 1
P
1 and 3
P
1 states with the mixing angle θ. In this work, considering the Z′ boson and setting the mixing angle θ=(−34±13)○, we analyze the branching ratio, the dilepton invariant mass spectrum, the normalized forward–backward asymmetry and lepton
polarization asymmetries of each decay mode. We find that all observables of B→K
1(1270)μ
+
μ
− are sensitive to the Z′ contribution. Moreover, the observables of B→K
1(1400)μ
+
μ
− have a relatively strong θ-dependence; thus, the Z′ contribution will be buried by the uncertainty of the mixing angle θ. Furthermore, the zero crossing position in the FBA spectrum of B→K
1(1270)μ
+
μ
− at low dilepton mass will move to the positive direction with Z′ contribution. For the tau modes, the effects of Z′ are not remarkable due to the small phase space. These results could be tested in the running LHC-b experiment and Super-B
factory. 相似文献
6.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2008,58(2):245-250
We study the final-state rescattering effects in the decay B
0→η
c
K
*. The numerical results indicate that the corrections are comparable with the contribution from the naive factorizable amplitude,
and the total amplitudes can accommodate the experimental data. 相似文献
7.
Within the framework of perturbative QCD factorization, we investigate the nonfactorizable contributions to the factorization-forbidden quasi-two-body decays \begin{document}$ B_{(s)}\rightarrow h\chi_{c0}\rightarrow h\pi^+\pi^-(K^+K^-) $\end{document} ![]()
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with \begin{document}$ h=\pi, K $\end{document} ![]()
![]()
. We compare our predicted branching ratios for the \begin{document}$ B_{(s)}\rightarrow K\chi_{c0}\rightarrow K\pi^+\pi^-(K^+K^-) $\end{document} ![]()
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decay with available experiment data as well as predictions by other theoretical studies. The branching ratios of these decays are consistent with data and other theoretical predictions. However, in the Cabibbo-suppressed decays \begin{document}$ B_{(s)}\rightarrow h\chi_{c0}\rightarrow h\pi^+\pi^-(K^+K^-) $\end{document} ![]()
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with \begin{document}$ h=\bar{K}^0,\pi $\end{document} ![]()
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, the values of the branching ratios are of the order of \begin{document}$ 10^{-7} $\end{document} ![]()
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and \begin{document}$ 10^{-8} $\end{document} ![]()
![]()
. The ratio \begin{document}$ R_{\chi_{c0}} $\end{document} ![]()
![]()
between the decays \begin{document}$B^+\rightarrow $\end{document} ![]()
![]()
\begin{document}$ \pi^+\chi_{c0}\rightarrow \pi^+\pi^+\pi^-$\end{document} ![]()
![]()
and \begin{document}$ B^+\rightarrow K^+\chi_{c0}\rightarrow K^+\pi^+\pi^- $\end{document} ![]()
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and the distribution of branching ratios for different decay modes in invariant mass are considered in this study. 相似文献
8.
Reinvestigating B → PV decays by including contributions from ?B2 with the perturbative QCD approach
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Considering the B mesonic wave function \begin{document}$ {\phi}_{B2} $\end{document} ![]()
![]()
, \begin{document}$ B {\to} PV $\end{document} ![]()
![]()
decays are restudied in the leading order for three scenarios using the perturbative QCD approach within the standard model, where \begin{document}$ P = {\pi} $\end{document} ![]()
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and K, and V denotes the ground \begin{document}$S U(3)$\end{document} ![]()
![]()
vector mesons. It is found that contributions from \begin{document}$ {\phi}_{B2} $\end{document} ![]()
![]()
can enhance most branching ratios and are helpful for improving the overall consistency of branching ratios between the updated calculations and available data, although there are still several discrepancies between the experimental and theoretical results. 相似文献
9.
10.
Marisílvia Donadelli 《Indian Journal of Physics》2011,85(1):27-32
The ratio of the ψ′ over the J
ψ production cross section in the dielectron channel has been measured in $
\sqrt s
$
\sqrt s
= 200 GeV p + p collisions with the PHENIX detector at RHIC. The analysis is based on fitting of the dielectron invariant mass spectra in
the area around the J
ψ and ψ′ signals in order to extract a ratio ψ′ over J
ψ of 0.019 ± 0.005 (stat) ± 0.002 (sys) and a fractional feed-down contribution to J
ψ from ψ′ of 8.6 ± 2.5%. 相似文献
11.
V. A. Kovalchuk 《Physics of Atomic Nuclei》2007,70(4):722-731
A method for determining the angle γ and the ratio of the amplitudes A
λ(B
− →
K
*−) and A
λ)B
− → D
*0
K
*−), r
Bλ, for all three vector-meson polarization states by using the decays B
∓ → D
*
K
*∓ is proposed. This method relies on the interference between the decays B
− → D
*0
K
*− and B
− →
K
*−, which arises if D
*0 and
decay to D
0/
π
0 and D
0/
γ, whereupon D
0 and
mesons decay to common final hadron states. The doubly Cabibbo-suppressed modes of D
0-meson decay are chosen here to specify such final states.
Original Russian Text ? V.A. Kovalchuk, 2007, published in Yadernaya Fizika, 2007, Vol. 70, No. 4, pp. 754–763. 相似文献
12.
S. Rai Choudhury A. S. Cornell Naveen Gaur 《The European Physical Journal C - Particles and Fields》2008,58(2):251-259
Flavor changing neutral current (FCNC) decays of the B-meson are a very useful tool for studying possible physics scenarios beyond the standard model (SM), where of the many FCNC
modes radiative, purely leptonic and semi-leptonic decays of the B-meson are relatively clean tests. Within this context, the BELLE collaboration has measured the process B→K
*
γ and also searched for the B→K
1(1270)γ process. Theoretical analyses of these processes are yielding similar values of the relevant form factors. In this work we
have used this upper bound in studying the angular correlations for the related semi-leptonic decay mode B
−→K
1−(1270)(→ρ
0
K
−)ℓ
+
ℓ
−, where we have used the form factors that have already been estimated for the B→K
1(1270)γ mode. Note that the additional form factors that are required were calculated using large energy effective theory (LEET). 相似文献
13.
L. I. Ryabinkina O. B. Romanova S. S. Aplesnin 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(8):1050-1052
Electronic transitions of the metal-insulator type and magnetic transitions of the antiferromagnetic semiconductor-ferromagnetic
metal type are established in cation-substituted manganese sulfides Me
x
Mn1 − x
S (Me = Cr, Fe, V, Co), synthesized on the basis of MnS. The effect of negative colossal magnetoresistance is found and the regularities
of change in the conductivity type and magnetic order are analyzed.
Original Russian Text ? L.I. Ryabinkina, O.B. Romanova, S.S. Aplesnin, 2008, published in Izvestiya Rossiiskoi Akademii Nauk.
Seriya Fizicheskaya, 2008, Vol. 72, No. 8, pp. 1115–1117. 相似文献
14.
本文采用全相对论量子力学计算了H2X (X=O, S, Se, Te) 分子的双光子过程, 并考虑相对论效应对双光子过程的影响. 结果表明, 各个不可约表示对称态下激发能有着明显的差异,它反应了双光子吸收过程中选择能级的特点. 同时, 采用非相对论的对称匹配簇/组态相互作用方法 (SAC-CI) 计算其分子的单光子激发, 并与之比较. 双光子跃迁概率要比单光子跃迁概率小2–5个数量级; 同一主族, 随着原子序数的增加, 相对论效应对分子体系的激发能量、跃迁概率、振子强度的大小都有显著地影响; 除此之外,每个分子遵守分子对称群的选择原则. 本文中, 分子H2X (X=O, S, Se, Te) 的个别不可约表示对称态的跃迁矩分量和振子强度远远大于其他对称态下的跃迁矩分量和振子强度, 甚至大于单光子激发. 这不仅与分子的对称性有一定的关系, 而且应该是选择双光子跃迁能级的重要依据.
关键词:
全相对论量子力学
双光子激发
电偶极跃迁矩
振子强度 相似文献
15.
Murugesh Duraisamy Alexander L. Kagan 《The European Physical Journal C - Particles and Fields》2010,70(4):921-925
CLEO-c measurements of the timelike form factors F
π
, F
K
at ?s=3.671\sqrt{s}=3.671 GeV provide a direct probe of power corrections (PC’s) at energies near m
B
. PC’s in F
π,K
and B→Kπ,ππ are separated into perturbative and soft parts. In F
π,K
the latter are ≥O(10) larger. A PC fit to the B→Kπ,ππ data also yields a ≥O(10) soft-to-perturbative hierarchy for the QCD penguin PC’s. Hence, both can be attributed to dominance of the soft-overlap
between energetic (approximately) back-to-back collinear partons, and consistency of the B→Kπ,ππ fit with the Standard Model appears to be naturally realized. The CP asymmetries SKs p0S_{K_{s} \pi^{0}}, CKs p0C_{K_{s} \pi^{0}} are well determined, providing a clean test for new physics. 相似文献
16.
An X-ray method has been considered for determining the volume fraction of the B19′ martensite in semi-product NiTi alloys, which is based on comparing the total integrated intensity of its strongest reflections
with the total integrated intensity of reflections from the matrix B2 phase. It has been shown that the method enables one to determine the volume fraction of martensite with an error of about
1% both in textured and textureless samples. 相似文献
17.
18.
19.
Fang Su Yue-Liang Wu Yi-Bo Yang Ci Zhuang 《The European Physical Journal C - Particles and Fields》2012,72(3):1914
We provide a systematic study of charmless B
s
→PP, PV, VV decays (P and V denote pseudoscalar and vector mesons, respectively) based on an approximate six-quark operator effective Hamiltonian from
QCD. The calculation of the relevant hard-scattering kernels is carried out, the resulting transition form factors are consistent
with the results of QCD sum-rule calculations. By taking into account important classes of power corrections involving “chirally
enhanced” terms and the vertex corrections as well as weak annihilation contributions with non-trivial strong phase, we present
predictions for the branching ratios and CP asymmetries of B
s
decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. It is
found that the weak annihilation contributions with non-trivial strong phase have remarkable effects on the observables in
the color-suppressed and penguin-dominated decay modes. In addition, we discuss the SU(3) flavor symmetry and show that the
symmetry relations are generally respected. 相似文献
20.
采用基于密度泛函理论的第一性原理方法, 对具有缺陷型黄铜矿结构的半导体材料AⅡAl2C4Ⅵ(A=Zn, Cd, Hg; C =S, Se)的构型和电子结构进行研究, 并系统考察了各晶体的光学性质. 对于线性光学性质, 五种晶体在红外区和部分可见光区具有良好的透光性能, 其中HgAl2S4和HgAl2Se4晶体具有适中的双折射率. 在非线性光学性质方面, 该类晶体倍频效应较强, 理论预测得到的二阶静态倍频系数均较大(>20 pm/V). 体系的倍频效应主要来源于价带顶附近以S/Se 价p轨道为主要成分的能带向含有较多Al/Hg 价p成分的空带之间的跃迁. 通过与已商业化的AgGaC2晶体光学性质的对比, 结果表明HgAl2S4和HgAl2Se4是一类性能优良的红外非线性光学晶体材料. 相似文献