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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.
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
3.
Yu-Ming Wang M. Jamil Aslam Cai-Dian Lü 《The European Physical Journal C - Particles and Fields》2009,59(4):847-860
The exclusive weak decay of Λ
b
→Λ
γ and Λ
b
→Λ
l
+
l
− are investigated in the Appelquist–Cheng–Dobrescu model, which is an extension of the standard model in the presence of universal
extra dimensions. Employing the transition form factors obtained in the light-cone sum rules, we analyze how the invariant-mass
distribution, the forward–backward asymmetry and the polarization asymmetry of the Λ baryon of these decay modes can be used to constrain the only additional free parameter with respect to the standard model,
namely, the radius, R, of the extra dimension. Our results indicate that the Kaluza–Klein modes can lead to approximately 25% suppression of the
branching ratio of Λ
b
→Λ
γ; however, their contributions can bring about 10% enhancement to the decay rate of Λ
b
→Λ
l
+
l
−. It is shown that in the present scenario the zero position of the forward–backward asymmetry of Λ
b
→Λ
μ
+
μ
− is sensitive to the compactification parameter R, while the measurement of polarizations of Λ baryon in the Λ
b
decays are not a useful tool to provide any valuable information for the universal extra-dimension model. 相似文献
4.
The polarization of a bremsstrahlung photon during the processes ee
± → (eγ)e
± and ep → (eγ)p is calculated for peripheral kinematics in the high-energy limit, where the cross section does not decrease with the incident
energy. When the initial electron is unpolarized (longitudinally polarized), the final photon can be linearly (circularly)
polarized. The Stokes parameters of the photon polarization are calculated as a function of the kinematical variables of the
process: the energy of the recoil particle, the energy fraction of the scattered electron, and the polar and azimuthal angles
of the photon. The numerical results are given in the form of tables for typical values of the relevant kinematic variables.
The text was submitted by the authors in English. 相似文献
5.
J. Ryckebusch W. Van Nespen 《The European Physical Journal A - Hadrons and Nuclei》2004,20(3):435-441
Differential cross-sections for exclusive 16O(e,epp)14C processes are computed within a distorted-wave framework which includes central short-range correlations and intermediate
excitations. The cross-sections are compared to high-resolution data from the MAMI facility at Mainz for a central energy and momentum transfer of
MeV and
MeV, respectively. A fair agreement between the numerical calculations and data is reached when using spectroscopic information extracted from a 15N
C experiment. The comparison between the calculations and the data provides additional evidence that short-range correlations exclusively affect nucleon pairs with a small center-of-mass momentum residing in a relative S state.Received: 3 September 2003, Revised: 2 December 2003, Published online: 18 June 2004PACS:
24.10.-i Nuclear-reaction models and methods - 21.60.-n Nuclear-structure models and methods - 25.30.Fj Inelastic electron scattering to continuum 相似文献
6.
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
7.
8.
电子原子散射中的S,T,U参数可用来描述散射前后自旋状态的变化,研究精细结构水平上的散射激发振幅之间的关系,进而揭示电子原子碰撞过程中电子自旋-轨道耦合以及电子-电子交换等自旋相关效应.采用扭曲波玻恩近似计算了钠原子受电子散射S→P跃迁中的S,T,U参数,分析了多种入射能(2.2—60 eV)的电子与钠原子激发S→P跃迁过程的S,T,U参数随散射角的分布,其中对10 eV入射能的Sp参数与已报道实验数据符合一致.结果表明,较低能电子入射下的S,T,U参数随散射角的分布幅度和起伏都比较明显,入射能大于40 eV的电子入射,S,T,U参数的散射角分布变化很小.
关键词:
散射激发
S')" href="#">S
T')" href="#">T
U参数')" href="#">U参数
散射振幅
自旋相关效应 相似文献
9.
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
10.
Jeong Ho Ryu Hyong Sik Won Youn-Gon Park Sang Hyun Kim Won Young Song Hideo Suzuki Chulsoo Yoon 《Applied Physics A: Materials Science & Processing》2009,95(3):747-752
Rare-earth-doped oxynitride or nitride compounds have been reported to be photoluminescent and may then serve as new phosphors
because of their good thermal and chemical stabilities. In this work, Eu2+-doped β-SiAlON phosphor with a composition of Eu
x
Si6−z
Al
z
O
z
N8−z
(x=0.018, z=0.23) was prepared by gas-pressured solid state reaction. The crystallinity and particle morphology of the prepared phosphor
were characterized. The Stokes shift and zero-phonon line were calculated mathematically and estimated from the spectral data.
The temperature dependence of photoluminescence was measured from 25 to 250°C. The prepared Eu2+-doped β-SiAlON green phosphor showed superior thermal quenching property compared to silicate (SrBaSiO4:Eu2+) green phosphor. The white light-emitting diode (LED) back-lighting unit (BLU) using the prepared β-SiAlON:Eu2+ green phosphor exhibited higher color gamut than a commercial silicate phosphor. 相似文献
11.
N × N集成光开关阵列模型 总被引:9,自引:8,他引:1
报道了由2N个1 × N 多模干涉马赫-曾德尔光开关组成的N × N光开关阵列结构,分析了这种结构的开关阵列优势和局限性.用场传输矩阵方法建立了1 × N多模干涉光开关的光场传输方程.给出了光开关阵列从任一输入端输入、从任一输出端输出时阵列开关的工作条件.在上述原理及理论基础上分析了4×4光开关阵列的结构和工作条件. 相似文献
12.
把一维q变形振子的结论推广到D维q变形振子体系,得到了D维q变形振子体系的哈密顿算符形式,并求出了其本征值和在坐标象中的本征函数.结果显示,这是一个非线性振子. 相似文献
13.
Extensive dynamical \begin{document}$N/D$\end{document} ![]()
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calculations are conducted in the study of \begin{document}$S_{11}$\end{document} ![]()
![]()
channel low energy \begin{document}$\pi N$\end{document} ![]()
![]()
scatterings, based on various phenomenological model inputs of left cuts at the tree level. The subtleties of the singular behavior of the partial wave amplitude, at the origin of the complex \begin{document}$s$\end{document} ![]()
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plane, are analysed in detail. Furthermore, it is found that the dispersion representation for the phase shift, \begin{document}$\delta$\end{document} ![]()
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, must be modified in the case of \begin{document}$\pi N$\end{document} ![]()
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scatterings. An additional contribution from the dispersion integral exists, which approximately cancels the contribution of the two virtual poles located near the end points of the segment cut, induced by \begin{document}$u$\end{document} ![]()
![]()
channel nucleon exchanges. With limited reliance on the details of the dynamical inputs, the subthreshold resonance \begin{document}$N^*(890)$\end{document} ![]()
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survives. 相似文献
14.
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
15.
A general formalism for double and triple spin correlations of the reaction
is developed for the case of collinear kinematics. A complete polarization experiment allowing one to reconstruct all four
amplitudes describing this process is suggested. Furthermore, the spin observables of the inelastic charge-exchange reaction
(pp)(1
S
0 are analyzed in collinear kinematics within the single pN-scattering mechanism involving the subprocess pn → Δ0
p. The full set of spin observables, related to the polarization of one or two initial particles and one final particle, is
obtained in terms of three invariant amplitudes of the reaction pd → Δ(pp)(1
S
0) and the transition form factor d → (pp)(1
S
0). A complete polarization experiment for the reaction
(pp)(1
S
0) is suggested which allows one to determine three independent combinations of the four amplitudes of the elementary subprocess
.
The text was submitted by the authors in English. 相似文献
16.
测量了CdTe太阳电池器件从50kHz至1MHz频率范围的电容-电压特性,计算了吸收层的载流子浓度和空间电荷区的位置,电容-电压特性测试结果出现两个峰,峰特征与测试频率有关,用多结模型进行模拟分析,解释了实验结果.测量了电池从220K至300K的变温暗电流-电压特性,得出电池的反向暗饱和电流密度J0和二级管理想因子A,分析了J0,A随测量温度的变化,并讨论了电池器件的电流特性.
关键词:
CdTe太阳电池
电流-电压特性
电容-电压特性 相似文献
17.
I. O. Troyanchuk D. V. Karpinsky M. V. Bushinskii O. Prokhnenko M. Kopcevicz R. Szymczak J. Pietosa 《Journal of Experimental and Theoretical Physics》2008,107(1):83-89
Systems of solid solutions Bi1 − x
Ca
x
FeO3 (I) and Bi1 − x
CaxFeO1 − x
Ti
x
O3 (II) have been obtained and their properties have been studied using neutronography and M?ssbauer spectroscopy; magnetization
and permittivity have been measured. It is shown that an increase in the concentration of calcium ions in system I for x > 0.2 changes rhombohedral distortions of a unit cell (space group R3c) to tetragonal distortions (space group I4/mcm), while rhombohedral distortions in system II for x > 0.2 are replaced by orthorhombic distortions (space group Pnma). Analysis of the crystal structure has revealed strong anisotropy in vibrations of Bi and O ions in system I compounds.
Systems I and II are characterized by G-type antiferromagnetic ordering of magnetic moments. In system II, spontaneous magnetization
associated with the Dzyaloshinskii-Moriya interaction has been detected. According to M?ssbauer spectroscopy data, iron ions
in compounds I and II are in the trivalent state and charge compensation occurs due to the formation of oxygen vacancies.
The permittivity increases with the calcium concentration.
Original Russian Text ? I.O. Troyanchuk, D.V. Karpinsky, M.V. Bushinskii, O. Prokhnenko, M. Kopcevicz, R. Szymczak, J. Pietosa,
2008, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2008, Vol. 134, No. 1, pp. 105–112. 相似文献
18.
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
19.
N. I. Kourov V. V. Marchenkov V. G. Pushin A. V. Korolev E. B. Marchenkova H. W. Weber 《Physics of the Solid State》2008,50(11):2127-2132
The effect of atomic disordering and deviation from the Ni2MnGa stoichiometric composition on the low-temperature properties of alloys with magnetically controlled shape memory effect
is studied. The specific features of the magnetic, galvanomagnetic, and electrical properties of alloys with magnetically
controlled shape memory effect are discussed. The specific features of the magnetic, galvanomagnetic, and electrical properties
of alloys Ni50Mn25Ga25, Ni54Mn21Ga25, and Ni50Mn28.5Ga21.5 in the temperature range 2 ≤ T ≤ 80 K under magnetic fields H ≤ 12 MA/m are studied.
Original Russian Text ? N.I. Kourov, V.V. Marchenkov, V.G. Pushin, A.V. Korolev, E.B. Marchenkova, H.W. Weber, 2008, published
in Fizika Tverdogo Tela, 2008, Vol. 50, No. 11, pp. 2037–2042. 相似文献
20.
B. Feigin M. Jimbo T. Miwa E. Mukhin Y. Takeyama 《Communications in Mathematical Physics》2005,257(2):395-423
Quadratic relations are given explicitly in two cases of chiral conformal field theory, and monomial bases of the representation spaces are constructed by using the Fourier components of the intertwiners. The first case is the (2,1) primary fields for the (p,p)-minimal series Mr,s (1rp–1,1sp–1) for the Virasoro algebra where 1<p/p<2. We restrict ourselves to the case p3, for which the (2,1) primary field exists. The second case is the intertwiners corresponding to the two-dimensional representation for the level k integrable highest weight modules V() (0k) for the affine Lie algebra 相似文献