共查询到20条相似文献,搜索用时 78 毫秒
1.
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
2.
3.
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
4.
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
5.
We present a set of formulas using the solution of the QCD Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation
to extract of the exponents of the gluon distribution, λ
g
, and structure function, λ
S
, from the Regge-like behavior at low x. The exponents are found to be independent of x and to increase linearly with lnQ
2 and are compared with the most data from the H1 Collaboration. We also calculated the structure function F
2(x,Q
2) and the gluon distribution G(x,Q
2) at low x assuming the Regge-like behavior of the gluon distribution function at this limit and compared them with an NLO-QCD fit to
theH1 data, two-Pomeron fit, multipole Pomeron exchange fit, and MRST (A.D. Martin, R.G. Roberts, W.J. Stirling, and R.S.
Thorne), DL (A. Donnachie and P.V. Landshoff), and NLO GRV (M. Glük, E. Reya, and A. Vogt) fit results.
The text was submitted by the authors in English. 相似文献
6.
N. Boulaftali N. Ben Sari-Zizi H. Najib G. GranerH. Bürger E.B. MkadmiP. Pracna 《Journal of Molecular Spectroscopy》2002,214(1):35-51
The ν1 (A1, 1578.31 cm−1)/ν4(E, 1615.17 cm−1) Si-D stretching dyad of D3SiF has been studied by FTIR spectroscopy with a resolution of 2.4×10−3 cm−1. Only weak interactions of Coriolis (ΔK=±1, Δ?=±1) and α resonance (ΔK=±2, Δ?=?1) type between ν1 and ν4, and of ? (2,−4) type within ν4, were revealed. However, the v1=1 and v4=1 levels were found to be severely perturbed by the v3=v5=1 (E, 1590.37 cm−1) and v2=v3=1 (A1, 1604.25 cm−1) states. These perturbations are observable only near level crossings involving strong Coriolis and α interactions. The energy structure within these perturbers is severely complicated by strong Coriolis and α resonances and by ? (2, 2), ? (2,−1), and ? (2,−4) interactions as already revealed by the ν2(A1, 710.16 cm−1) and ν5 (E, 701.72 cm−1) fundamentals. Interactions of the perturbing states with the ν1/ν4 dyad are particularly evident in local crossings. In total, 12 transitions belonging to the dark states and 68 perturbation-allowed transitions within the ν1/ν4 dyad have been detected among the more than 5000 transitions that have been assigned for the ν1/ν4 dyad, with Jmax and Kmax of 50 and 30, respectively. Altogether about 85% of the assigned transitions were fitted with a standard deviation of 0.221×10−3 cm−1, leading to 61 parameters of the interacting polyad. 相似文献
7.
O.N Ulenikov E.S Bekhtereva V.A Kozinskaia Jing-Jing ZhengSheng-Gui He Shui-Ming HuQing-Shi Zhu C LeroyL Pluchart 《Journal of Molecular Spectroscopy》2002,215(2):295-308
The high-resolution (0.005 cm−1) Fourier transform infrared spectrum of PH3 is recorded and analyzed in the region of the fundamental stretching bands, ν1 and ν3. The ν2+ν4 and 2ν4 bands are taken into account also. Experimental transitions are assigned to the ν1, ν3, ν2+ν4, and 2ν4 bands with the maximum value of quantum number J equal to 15, 15, 13, and 15, respectively. a1-a2 splittings are observed and described up to the value of quantum number K equal to 10. The analysis of a1/a2 splittings is fulfilled with a Hamiltonian model which takes into account numerous resonance interactions among all the upper vibrational states. 相似文献
8.
Transition amplitudes and transition probabilities for the two-photon 1s–2s transition in the hydrogen atom and 11
s–21
s transition in helium atom have been calculated using a partial-closure approach. The dominant term is calculated exactly
and the remaining sum over intermediate states is calculated using a mean excitation energy. Our value of the transition amplitudes
agree within 2% with the exact results for the hydrogen case. Our value of the transition probability for hydrogen is 8.50
s−1 which is in good accord with its known value 8.226 s−1. For helium, the photon energy distribution of the metastable 21
s state is in good agreement with the accurate values. The corresponding transition probability is 53.7 s−1 which is in good agreement with the accurate value 51.3 s−1. 相似文献
9.
M. Carlotti G. di Lonardo G. Galloni A. Trombetti 《Journal of Molecular Spectroscopy》1976,62(2):192-200
The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm?1):
Band | B | C | ||
3533.1 | 27.0 | — | — | |
10145.79 | 22.6713 | 0.368426 | 0.361722 |