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1.
The two-photon decay widths of scalar mesons σ(600), f
0(980), and a
0(980) are calculated in the framework of the local Nambu-Jona-Lasinio model. The contributions of the quark loops (Hartree-Fock
approximation) and the meson loops (next 1/N
c
approximation, where N
c
is the number of colors) are taken into account. These contributions, as we show, are the values of the same order of magnitude.
For the f
0 decay the K-loop contribution turns out to play the dominant role. The results are in satisfactory agreement with modern experimental
data. 相似文献
2.
The widths with respect to the radiative decays f
0(980) → ργ and a
0(980) → ωγ were calculated within the local Nambu-Jona-Lasinio model. The contributions of both quark and meson loops were taken into
account. The latter and the former play a dominant role for the radiative decays of, respectively, the f
0(980) and the a
0(980) meson. 相似文献
3.
4.
We use a non-perturbative approach which combines coupled channel Lippmann-Schwinger equations with meson-meson potentials provided by the lowest order chiral Lagrangian. By means of one parameter, a cut off in the momentum of the loop integrals, which results of the order of 1 GeV, we obtain singularities in the S-wave amplitudes corresponding to the σ, f0 and a0 resonances. The ππ → ππ, phase shifts and inelasticities in the T = 0 scalar channel are well reproduced as well as the π0η and mass distributions in the T = 1 channel. Furthermore, the total and partial strong decay widths of the f0 and a0 resonances are properly reproduced. The results seem to indicate that chiral symmetry constraints at low energy and unitarity in coupled channels is the basic information contained in the meson-meson interaction below GeV. 相似文献
5.
On the basis of the decay couplings f
0 → ππ, K
, ηη, ηη′ found earlier in the study of analytical (IJ
PC
=00++) amplitude in the mass range 450–1900 MeV, we analyze the quark-gluonium content of the resonances f
0(980), f
0(1300), f
0(1500), and f
0(1750) and the broad state f
0(1420
−70
+150
). The K-matrix technique used in the analysis makes it possible to evaluate the quark-gluonium content both for the states with switched-off
decay channels (bare states, f
0
bare
) and for the real resonances. We observe a significant change in the quark-gluonium composition in the evolution from bare
states to real resonances, which is due to the mixing of states in the transitions f
0(m
1) → real mesons → f
0 (m
2) responsible for the decay processes as well. For f
0(980), the analysis confirmed the dominance of q
component, thus proving the n
/s
composition found in the study of the radiative decays. For the mesons f
0(1300), f
0(1500), and f
0(1750), the hadronic decays do not allow one to determine uniquely the n
, s
, and gluonium components, providing relative percentage only. The analysis shows that the broad state f
0(1420
−70
+150
) can mix with the flavor singlet q
component only, which is consistent with gluonium origin of the broad resonance.
From Yadernaya Fizika, Vol. 66, No. 4, 2003, pp. 772–785.
Original English Text Copyright ? 2003 by Anisovich, Nikonov, Sarantsev.
This article was submitted by the authors in English. 相似文献
6.
7.
通过显微光致发光技术和显微拉曼(Raman)技术研究了半绝缘GaAs (SI-GaAs)晶体的带边附近的发光. 在光荧光谱中,观察到在高于GaAs带边0.348eV处有一个新的荧光峰. 结合Raman谱指认此发光峰来源于GaAs的E0+Δ0能级的非平衡荧光发射. 同时, 通过研究E0+Δ0能级的偏振、激发光强度依赖关系,以及温度依赖关系说明E0+Δ0能级与带边E0共享了共同的导带位置Γ6,同时这也说明在GaAs中主要是导带的性质决定了材料的光学行为.同时,通过与n-GaAs和δ掺杂GaAs相比较,半绝缘GaAs晶体的E0+Δ0能级的发光峰更能反映GaAs电子能级高临界点E0+Δ0的能量位置和物理性质. 研究结果说明显微光致发光技术是研究半导体材料带边以上能级光学性质的一种非常有力的研究工具.
关键词:
半绝缘GaAs
显微光致发光
自旋轨道分裂 相似文献
8.
O. S. Alekseeva A. Z. Devdariani A. L. Zagrebin M. G. Lednev 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(6):946-951
A semiempirical method of analysis of quasi-molecular terms in conjunction with experimental potentials of interaction of
Hg(6(3
P
1)) atoms with Ar, Kr, and Xe atoms are used to obtain the Hg(63
P
2)-Ar, Kr, Xe interaction potential, which are applied to calculating the radiative lifetimes of the v′1(3
P
2) states of the HgAr, HgKr, and HgXe molecules and the probabilities of the v′1(3
P
2)−v″0+(1
S
0) transitions. 相似文献
9.
Absorption spectra of β -carotene in 31 solvents
are measured in ambient conditions. Solvent effects on the 0--0 band
energy, the bandwidth, and the transition moment of the S0 →
S2 transition are analysed. The discrepancies between published
results of the solvent effects on the 0--0 band energy are
explained by taking into account microscopic solute-solvent
interactions. The contributions of polarity and polarizability of
solvents to 0--0 band energy and bandwidth are quantitatively
distinguished. The 0--0 transition energy of the S2 state at the gas
phase is predicted to locate between 23000 and 23600~cm-1. 相似文献
10.
V. V. Vien 《中国物理C(英文版)》2021,45(12):123103-123103-14
We construct a non-renormalizable gauge \begin{document}$ B-L $\end{document} ![]()
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model based on \begin{document}$ Q_4\times Z_4\times Z_2 $\end{document} ![]()
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symmetry that successfully explains the cobimaximal lepton mixing scheme. Small active neutrino masses and both neutrino mass hierarchies are produced via the type-I seesaw mechanism at the tree-level. The model is predictive; hence, it reproduces the cobimaximal lepton mixing scheme, and the reactor neutrino mixing angle \begin{document}$ \theta_{13} $\end{document} ![]()
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and the solar neutrino mixing angle \begin{document}$ \theta_{12} $\end{document} ![]()
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can obtain best-fit values from recent experimental data. Our model also predicts the effective neutrino mass parameters of \begin{document}$ m_{\beta }\in (8.80, 9.05)\, \mathrm{meV} $\end{document} ![]()
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and \begin{document}$ \langle m_{ee}\rangle \in (3.65, 3.95)\, \mathrm{meV} $\end{document} ![]()
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for normal ordering (NO) and \begin{document}$ m_{\beta }\in (49.16, 49.21)\, \mathrm{meV} $\end{document} ![]()
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and \begin{document}$ \langle m_{ee}\rangle \in (48.59, 48.67)\, \mathrm{meV} $\end{document} ![]()
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for inverted ordering (IO), which are highly consistent with recent experimental constraints. 相似文献
11.
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
12.
13.
Najate Bensari-zizi Claude Alamichel 《International Journal of Infrared and Millimeter Waves》1989,10(1):137-151
About 2500 lines of CH3
35Cl have been assigned. The strong xy Coriolis resonance between thev
2 andv
5 modes is quite visible between thev
4+v
4
±1
perpendicular band, centered around 4383 cm–1, and thev
4
±1
+v
5
±1
perpendicular component, centered around 4475 cm–1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev
4
1
+v
5
±1
parallel component is nevertheless detectable by its effects onv
2+v
4
±1
which is linked by Coriolis resonance to both components ofv
4+v
5. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv
2+3v
6
±1
, connected tov
2+v
4
±1
by the well known Darling Dennison resonance which couplesv
4
±1
and 3v
6
±1
, and also ofv
5
±1
+3v
6
±1
connected tov
4
±1
+v
5
±1
by the same resonance; but this last case is complicated by an anharmonic resonance betweenv
5
±1
+3v
6
±1
and 2v
3+3v
6
1
. Two more perturbations occur on the K=–1 side ofv
2+v
4: a weak Coriolis resonance gives rise to one subband ofv
1+v
2 at a level crossing withv
2+v
4, and thev
1+v
5 band (linked of course tov
1+v
2 by the Coriolis resonance between thev
2 andv
5 modes) is quite visible and perturbs several subbands ofv
2+v
4 of high values of K through an anharmonic resonance. Moreover, the complex (3v
5
±1
,v+2v
5
0
, 2v
2+v
5
±1
, 3v
2,v
2+2v
5
±2
, 3v
5
±3
) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv
2+2v
5
0
andv
1+v
2, and the other one betweenv
1+v
5 and 3v
5
±1
, whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult. 相似文献
14.
R. J. Apsimon M. Atkinson M. Baake L. S. Bagdasarian D. Barberis T. J. Brodbeck N. Brook T. Charity A. B. Clegg P. Coyle et al. 《Zeitschrift fur Physik C Particles and Fields》1992,56(2):185-192
Measurements are reported of inclusive production of -mesons in the beam fragmentation region in p, p andKp collisions. Results include a small but significant departure from VMD, and a pronounced rise in the/
0 ratio with increasingp
T
. 相似文献
15.
利用激光脉冲沉积(PLD)技术在(302)γ-LiAlO2衬底上成功生长了非极性的a面(1120)ZnO薄膜,光致发光谱(PL)带边发射峰半峰宽仅为115meV.研究了非极性ZnO薄膜光谱特性的面内各向异性,发现随着入射光偏振方向改变,在偏振透射光谱上,吸收边移动了20meV,这与A、B激子和C激子的能量差一致;而在拉曼光谱上,激发光偏振方向的改变导致E2模式的强度发生明显改变.
关键词:
非极性ZnO
2')" href="#">γ-LiAlO2
PLD 相似文献
16.
17.
Extensive dynamical \begin{document}$N/D$\end{document} ![]()
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calculations are conducted in the study of \begin{document}$S_{11}$\end{document} ![]()
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channel low energy \begin{document}$\pi N$\end{document} ![]()
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scatterings, based on various phenomenological model inputs of left cuts at the tree level. The subtleties of the singular behavior of the partial wave amplitude, at the origin of the complex \begin{document}$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$\end{document} ![]()
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channel nucleon exchanges. With limited reliance on the details of the dynamical inputs, the subthreshold resonance \begin{document}$N^*(890)$\end{document} ![]()
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survives. 相似文献
18.
In terms of the adiabatic theory of interactions, we consider the results of the theoretical estimation of the rate constants
K
ST
of the nonradiative intersystem crossing conversion S
1(ππ*) ⇝ T
1
S
(ππ*) for nine aromatic molecules containing 10–14 carbon atoms and one or two heavy (many-electron) oxygen or chlorine atoms. 相似文献
19.
O. Félix-Beltrán M. Gómez-Bock E. Hernández A. Mondragón M. Mondragón 《International Journal of Theoretical Physics》2011,50(7):2291-2303
We study the singularity of the surface that represents the masses of the isolated doublet of heavy, neutral Higgs bosons,
H
2–H
3, in a toy model based on the MSSM with CP violation, in parameter space. These two heavy, neutral Higgs bosons are coherent
and, for large values of the masses, nearly degenerate. In this scenario, mixing between the mass eigenstates of the H
2–H
3 system could be very large and exact degeneracy is possible. As function of the Lagrangian parameters, the physical mass
of the doublet has an algebraic branch point of rank one at the exceptional point where the two masses are equal. The real
and imaginary parts of the masses in the doublet have branch cuts that start at the same branch point but extend in opposite
directions in parameter space. Associated with this branch point, the propagator of the mixing doublet of neutral heavy Higgs
bosons has a double pole in the complex s-plane of the energy squared. We computed the mass surface of the isolated doublet of H
2–H
3 bosons as function of the Lagrangian parameters in the neighbourhood of the exceptional point in a toy model of the system
H
2–H
3. We also computed the trajectories of the poles of the transition matrix for values of the Lagrangian parameters close to
the exceptional point and explained the characteristic change of identity seen in these trajectories in the s-plane as a manifestation of the topology of the two-sheeted mass surfaces in the space of Lagrangian parameters. 相似文献
20.
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