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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.
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
3.
L. A. Kondratyuk E. L. Bratkovskaya V. Yu. Grishina M. Büscher W. Cassing H. Str?her 《Physics of Atomic Nuclei》2003,66(1):152-171
We consider near-threshold a
0(980)-meson production in πN and NN collisions. An effective Lagrangian approach with one-pion exchange is applied to analyze different contributions to the
cross section for different isospin channels. The Reggeon exchange mechanism is also evaluated for comparison. The results
from πN reactions are used to calculate the contribution of the a
0 meson to the cross sections and invariant
mass distributions of the reactions
and pp → ppK
+
K
−. It is found that the experimental observation of a
0
+
mesons in the reaction
is much more promising than the observation of a
0
0
mesons in the reaction pp → ppK
+
K
−. Effects of isospin violation in the reactions pN → da
0, pd → 3He(3H)a
0, and dd → 4Hea
0, which are induced by a
0(980)-f
0(980) mixing, are also analyzed.
From Yadernaya Fizika, Vol. 66, No. 1, 2003, pp. 155–174.
Original English Text Copyright ? 2003 by Kondratyuk, Bratkovskaya, Grishina, Büscher, Cassing, Str?her.
This article was submitted by the authors in English. 相似文献
4.
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
5.
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
6.
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
7.
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
8.
9.
10.
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
11.
12.
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
13.
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 $\end{document} ![]()
![]()
model based on \begin{document}$ Q_4\times Z_4\times Z_2 $\end{document} ![]()
![]()
symmetry that successfully explains the cobimaximal lepton mixing scheme. Small active neutrino masses and both neutrino mass hierarchies are produced via the type-I seesaw mechanism at the tree-level. The model is predictive; hence, it reproduces the cobimaximal lepton mixing scheme, and the reactor neutrino mixing angle \begin{document}$ \theta_{13} $\end{document} ![]()
![]()
and the solar neutrino mixing angle \begin{document}$ \theta_{12} $\end{document} ![]()
![]()
can obtain best-fit values from recent experimental data. Our model also predicts the effective neutrino mass parameters of \begin{document}$ m_{\beta }\in (8.80, 9.05)\, \mathrm{meV} $\end{document} ![]()
![]()
and \begin{document}$ \langle m_{ee}\rangle \in (3.65, 3.95)\, \mathrm{meV} $\end{document} ![]()
![]()
for normal ordering (NO) and \begin{document}$ m_{\beta }\in (49.16, 49.21)\, \mathrm{meV} $\end{document} ![]()
![]()
and \begin{document}$ \langle m_{ee}\rangle \in (48.59, 48.67)\, \mathrm{meV} $\end{document} ![]()
![]()
for inverted ordering (IO), which are highly consistent with recent experimental constraints. 相似文献
14.
E. A. Gastilovich V. G. Klimenko N. V. Korol’kova R. N. Nurmukhametov 《Optics and Spectroscopy》2011,110(2):201-210
By calculating the matrix elements of operators of adiabatic and nonadiabatic interactions, which determine the process T
1
S
↝ S
0 in molecules of naphthalene and its 1,4- and 2,3-dichloro-substituted derivatives, we study how various factors of intramolecular
interactions affect this process. The effects of α and β chlorine substituents on spin-orbit (SO) interactions in the carbon
backbone of the molecule and in its chlorine atoms, where the compensation effect of SO interactions was revealed, are separated.
It is found that high-frequency out-of-plane promoting modes (corresponding to vibrations of CCH groups) differently affect
SO interactions in the carbon backbone of molecules and in chlorine atoms. 相似文献
15.
The Fourier transform infrared (FTIR) spectrum of the ν8 fundamental band of ethylene-d3 (C2HD3) was recorded with a unapodized resolution of 0.0063 cm−1 in the wavenumber region of 840–980 cm−1. By assigning and fitting a total of 738 infrared transitions using a Watson’s A-reduced Hamiltonian in the Ir representation, rovibrational constants for the upper state (ν8 = 1) up to all five quartic centrifugal distortion terms were derived for the first time. The root-mean-square (rms) deviation of the fit was 0.00076 cm−1. The ground state rovibrational constants of C2HD3 were also determined for the first time by a fit of 450 combination-differences from the present infrared measurements, with rms deviation of 0.00075 cm−1. Local frequency perturbations were not detected in the C-type ν8 band of C2HD3 which is centred at 918.73199 ± 0.00007 cm−1. 相似文献
16.
考虑系统噪声和时滞,利用L2—L∞控制理论研究了有leader的二阶定拓扑多智能体系统的协调一致问题.工程应用中控制输出的极大值经常需控制在一定范围内,并且考虑系统对位置变量和速度变量限制的范围不同,分别针对位置和速度的控制输出设计了加权系数;进而建立了多智能体系统的数学模型.对有时滞和无时滞的两种网络拓扑,利用李亚普诺夫函数,分析了多智能体系统在满足L2—L∞性
关键词:
L2—L∞控制')" href="#">L2—L∞控制
多智能体系统
一致问题
时滞 相似文献
17.
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
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.