共查询到20条相似文献,搜索用时 281 毫秒
1.
G. A. Kozlov 《Physics of Particles and Nuclei》2010,41(6):954-956
A field model for a quark and an antiquark binding is described. Quarks interact via a gauge unparticle (“ungluon”). The model
is formulated in terms of Lagrangian which features the source field S(x) which becomes a local pseudo-Goldstone field of conformal symmetry — the pseudodilaton mode and from which the gauge non-primary
unparticle field is derived by B
μ(x) ∼ ∂μ
S(x). Because the conformal sector is strongly coupled, the mode S(x) may be one of new states accessible at high energies. We have carried out an analysis of the important quantity that enters
in the “ungluon” exchange pattern — the “ungluon” propagator. 相似文献
2.
Takao Itoh 《Journal of Molecular Spectroscopy》2008,252(2):115-120
Fluorescence and excitation spectra of coronene vapor have been measured under different conditions. Weak emission which can be regarded as the fluorescence from the third excited singlet state, S3(1E1u), was observed in addition to the S1(1B2u) and S2(1B1u) fluorescence. The observed S2 and S3 fluorescence are substantially different from those reported previously for coronene vapor. Addition of oxygen resulted in significant decrease of the S1 fluorescence intensity, but did not affect the S2 fluorescence intensity, indicating the faster decay rate of the S2 state than that of S1. Excitation energy dependence of the S1, S2 and S3 fluorescence quantum yields (ΦF(S1), ΦF(S2) and ΦF(S3), respectively) revealed that ΦF(S1) decreases with increasing excitation energy, while ΦF(S2) and ΦF(S3) increase significantly. The quantum yield ratios, ΦF(S2)/ΦF(S1) and ΦF(S3)/ΦF(S2), obtained as a function of excitation energy are correlated with the ratios of the relative internal conversion rates. 相似文献
3.
Graham M Shore 《Annals of Physics》1981,137(2):262-305
Spontaneously broken gauge theories in a constant external electromagnetic field are shown to exhibit a first-order phase transition to a restored symmetry phase when the external field exceeds a certain critical value. The effects of fields characterized by various values of the two Lorentz invariants and F2 = E · B are discussed. In a simple SU(2) model the critical field strength is found to be gR2(F1)crit = 0.057 mw4, mw being the vector boson mass. A number of theoretical developments in the background field formalism are presented. A new gauge-fixing term, the background field R gauge, is introduced. The configuration space heat kernel method for evaluating functional determinants, extended to allow the use of dimensional regularization, is employed, and it is shown how to perform background field calculations in a gauge specified by an arbitrary parameter α. Further applications of these methods are discussed. 相似文献
4.
Jian‐Li Guo Chong Liu Bin‐Bin Xie Yan‐Ying Zhao Ke‐Mei Pei Hui‐Gang Wang Xuming Zheng Yue‐Jie Ai Xue‐Bo Chen Wei‐Hai Fang Chi Shun Yeung 《Journal of Raman spectroscopy : JRS》2012,43(10):1477-1486
The photophysics and photochemistry of pyrazine (C4H4N2, D2h) after excitation to the S2 (1 1B2u, 1ππ*) electronic state were studied by using the resonance Raman spectroscopy and complete active space self‐consistent field method calculations. The B‐band resonance Raman spectra in cyclohexane solvent were obtained at 266.0, 252.7, and 245.9 nm excitation wavelengths to probe the structural dynamics of pyrazine in the S2 (1 1B2u, 1ππ*) state. Three electronic states 1 1B3u, 1 1B1g, and 1 1B2g were found to couple with the S2 (1 1B2u, 1ππ*) state. Two conical intersection (CI) points CI[S2(B2u)/S1(B3u)] and CI[S1/S0] and one transition state of the isomerization between pyrazine and pyrimidine were predicted to play important roles in the photochemistry of pyrazine. On the basis of the calculations, the mechanism of the photoisomerization reaction between pyrazine and pyrimidine has been proposed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
5.
Hyperfine splittings (HFS) are calculated within the Field Correlator Method, taking into account relativistic corrections.
The HFS in bottomonium and the B
q
(q = n, s) mesons are shown to be in full agreement with experiment if a universal coupling α
HF = 0.310 is taken in perturbative spinspin potential. It gives M(B*) −M(B) = 45.7(3) MeV, M(B
s
* ) − M(B
s
) = 46.7(3) MeV (n
f
= 4), while in bottomonium ΔHF(b
$
\bar b
$
\bar b
) = M(Υ(9460)) − M(η
b
(1S)) = 63.4 MeV for n
f
= 4 and 71.1 MeV for n
f
= 5 are obtained; just the latter agrees with recent BaBar data. For unobserved excited states we predict M(Υ(2S))−M(η
b
(2S)) = 36(2)MeV,M(Υ(3S))−M(η
b
(3S)) = 28(2)MeV, and also M(B
c
*) = 6334(4) MeV, M(B
c
(2S)) = 6868(4) MeV, M(B
c
* (2S)) = 6905(4) MeV. The mass splittings between D(23
S
1) − D(21
S
0), D
s
(23
S
1) − D
s
(21
S
0) are predicted to be ∼75 MeV, which are significantly smaller than in several other studies but agree with the mass splitting
between recently observed D(2533) and D*(2610). 相似文献
6.
Tadeusz Bałaban John Imbrie Arthur Jaffe 《Communications in Mathematical Physics》1985,97(1-2):299-329
We study the effective actionsS
(k) obtained byk iterations of a renormalization transformation of the U(1) Higgs model ind=2 or 3 spacetime dimensions. We identify a quadratic approximationS
Q
(k)
toS
(k) which we call mean field theory, and which will serve as the starting point for a convergent expansion of the Green's functions, uniformly in the lattice spacing. Here we show how the approximationsS
Q
(k)
arise and how to handle gauge fixing, necessary for the analysis of the continuum limit. We also establish stability bounds onS
Q
(k)
, uniformly ink. This is an essential step toward proving the existence of a gap in the mass spectrum and exponential decay of gauge invariant correlations.Dedicated to the memory of Kurt SymanzikSupported in part by the National Science Foundation under Grant PHY 82-03669 相似文献
7.
J. Horbach W. Kob K. Binder 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(4):531-543
We present the results of extensive molecular dynamics computer simulations in which the high frequency dynamics of silica,
i.e. for frequencies ν > 0.5 THz, is investigated in the viscous liquid state as well as in the glass state. We characterize the
properties of high frequency sound modes by analyzing J
l(q,ν) and J
t(q,ν), the longitudinal and transverse current correlation function, respectively. For wave-vectors q > 0.4 ?-1 the spectra are sitting on top of a flat background. The dynamic structure factor S(q,ν) exhibits for q > 0.23 ?-1 a boson peak which is located nearly independent of q around 1.7 THz and for which the intensity scales approximately linearly with temperature. We show that the low frequency
part of the boson peak is mainly due to the elastic scattering of transverse acoustic modes with frequencies around 1 THz.
The strength of this scattering depends on q and is largest around q = 1.7 ?-1, the location of the first sharp diffraction peak in the static structure factor. By studying S(q,ν) for different system sizes we show that strong finite size effects are present in the low frequency part of the boson
peak in that for small systems part of its intensity is missing. We discuss the consequences of these finite size effects
for the structural relaxation.
Received 27 June 2000 and Received in final form 9 January 2001 相似文献
8.
E. Sezgin 《Fortschritte der Physik》1986,34(4):217-259
We derive the complete particle spectrum of the d = 11 supergravity compactified on AdS X S7, by analytically continuing AdS to S4, and using the Salam-Strathdee method of harmonic expansion on S4 X S7. The spectrum is arranged into supermultiplets labelled by an integer l = 0, 1, 2,. The massless supermultiplet corresponds to l = 0. For the l'th supermultiplet we find a relation, involving the eigenvalues of the second order Casimir operators of SO(3, 2) and SO(8), given by 2C2[SO(3, 2)] + C2[SO(8)] = 3/2(l + 2) (l + 4). 相似文献
9.
K. H. Hellwege S. Hüfner M. Schinkmann H. Schmidt 《Zeitschrift für Physik B Condensed Matter》1966,4(5):397-403
The optical absorption spectrum of Erbium Aluminum Garnet (ErAlG) has been measured between 12000 cm?1 and 26000 cm?1. The crystal field splitting of the terms4I15/2,4I9/2,4F9/2,4S3/2,2H11/2,4F7/2,4F5/2,4F3/2,2H9/2 and4G11/2 was determined from the spectra and has been analysed in terms of the usual parametrization scheme. Nine crystal field parametersA l m 〈r l〉≡B l m which are necessary to describe the crystal field with the symmetryD 2 at the site of the rare earth ion, were fitted to the experimental data. The values are (in cm?1):B 2 0=+160B 4 0=?160B 6 0=+30B 6 6=+80B 2 2=?100B 4 2=+140B 2 6=?40B 4 4=?1800B 6 4=?700 This result is compared with those obtained from similar analysis of other garnets. 相似文献
10.
The entropy of entanglement between a three-dimensional slab of thickness l and its complement is studied numerically for four-dimensional SU(2) lattice gauge theory. We find a signature of a nonanalytic behavior of the entanglement entropy, which was predicted recently for large Nc confining gauge theories in the framework of AdS/CFT correspondence. The derivative of the entanglement entropy over l is likely to have a discontinuity at some l=lc. It is argued that such behavior persists even at finite temperatures, probably turning into a sort of crossover for temperatures larger than the temperature of the deconfinement phase transition. We also confirm that the entanglement entropy contains quadratically divergent l-independent term, and that the nondivergent terms behave as l−2 at small distances. 相似文献
11.
Approximating the shape of the magneto-thermoelectric power (TEP) ΔS(T,H) measured in Bi2Sr2CaCu2Oy by an asymmetric linear triangle of the form ΔS(T,H)≃S
p
(H)±B
±(H)(T
c
−T) with positive B
−(H) and B
+(H) defined below and above T
c
, we observe that B
+(H) ≃2B
−(H). To account for this asymmetry, we explicitly introduce the field-dependent chemical potential μ(H) of holes into the Ginzburg-Landau theory and calculate both an average ΔS
av(T,H) and fluctuation contribution ΔS
fl(T,H) to the total magneto-TEP ΔS(T,H). As a result, we find a rather simple relationship between the field-induced variation of the chemical potential in this
material and the above-mentioned magneto-TEP data around T
c
, viz. Δ μ(H)∝S
p
(H).
Zh. éksp. Teor. Fiz. 116, 257–262 (July 1999)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
12.
A theoretical study has been made of the dependence of the 1 J(HD) coupling in HD on the interatomic distance R in the presence of a static uniform magnetic field B 0. The behaviour of all coupling terms arising from Ramsey's magnetic electron-nucleus interactions, Fermicontact (FC), spin-dipolar (SD) and paramagnetic (PSO) and diamagnetic (DSO) spin-orbital interactions is analysed qualitatively for large R. It is concluded that the PSO, DSO and SD terms become negligibly small as R increases. Detailed calculations were carried out for the FC term following two different approaches: detailed full CI calculations within a non-perturbative approach; and explicit diagonalization of the Hamiltonian operator restricted to the subspace spanned by the 1Σ+;g and the 3Σ+;u states. Within the approximations considered, the FC term of 1 J(HD) is found to be independent of B 0 and to increase by several orders of magnitude, in agreement with previous results by Bacskay, G. B., 1995, Chem. Phys. Lett., 242, 507, until a critical distance R(B 0) is reached, beyond which it almost vanishes. The quenching of the coupling at R(B 0) is due to the splitting of the 3Σ+;u state in the presence of the field B 0. The stronger the field the shorter is R(B 0). 相似文献
13.
The Bethe-Salpeter formalism is used to incorporate the valence Regge behavior into the total DIS amplitude. For a special
case of scalar quarks with massless scalar exchange, the model is solved both analytically and numerically and exact scaling
is found for the valence quark contribution F
2(x) ∼ (1/x)
l(0)−1 which mimicks the ρ-trajectory term. The solution solves a long-standing problem by showing that the coefficient in the Regge
pole expansion is indeed fine-tuned to give the expected scaling. The method allows for generalization to the region of nonzero
momentum transfer and calculation of the DVCS amplitude.
The text was submitted by the authors in English. 相似文献
14.
TheU
B(6)⊗U
F(20) Bose-Fermi dynamical symmetry of interacting boson-fermion model arises when the odd nucleon occupies single particle
orbits withj=1/2, 3/2, 5/2, and 7/2. The subgroup structures ofU
B(6)⊗U
F(20) related to theU
B(5) andO
B(6) limits of sdIBM (U
B(6)) are analysed. Broadly speaking,U
B(6)⊗U
F(20) admitsU
BF(5)⊗U
s
F
(4), SpinBF(5)⊗U
k
F
(5) andU
BF(5)⊗U
s
F
(2) limits withU
B(5) core and SpinBF(6),O
BF(5)⊗U
s
F
(4), SpinBF(6)⊗U
k
F
(5) andO
BF(6)⊗U
s
F
(2) limits withO
B(6) core respectively. For each of these seven symmetry limits, group chains, quantum numbers labelling the basis states,
generators and Casimir operators for the various subgroups and energy formulas are given. Recoupling coefficients (reduced
Wigner coefficients) for constructing wavefunctions of low-lying states are tabulated and these will allow (together with
sdIBMU
B(5) andO
B(6) limit results) one to calculateB(E2)’s,B(M1)’s, one and two nucleon transfer strengths etc. in the seven symmetry limits. Experimental examples for theU
B(6)⊗U
F(20) symmetry limits are briefly discussed. 相似文献
15.
《Physics letters. [Part B]》1988,211(3):259-264
We show that a wide range of deformed actinides can be described in terms of an interacting boson model hamiltonian with three parameters, two of them [including the coefficient of the only SU(3) symmetry breaking term] remaining almost constant over the whole region. In addition to ground γ1 and β1 spectra, B(E2:0g+ → 2g+) values are well reproduced with no extra adjustable parameters for nuclei with 136⩽N⩽146, while for nuclei beyond N = 146 an effective boson number has to be considered in order to fit the observed in the B(E2:0+g → 2+g) values, which is due to the presensce of a subshell closure at N = 152. The sensitive dependence of the B(E2:0g+→2g+) values on the effective boson numbers is emphasized. β1 → ground and β1 → ground transitions are fitted by breaking the SU(3) symmetry of the E2 transition operator. 相似文献
16.
Takao Itoh 《Molecular physics》2013,111(16):1705-1711
Fluorescence and excitation spectra of all-trans-2,4,6,8-decatetraene vapour have been measured at different buffer gas pressures from 0 to 1.07 × 105 Pa (800 Torr). The quantum yield of the S1 fluorescence (ΦF(S1)) increases with increasing the buffer gas pressure, while that of the S2 fluorescence (ΦF(S2)) decreases slightly. ΦF(S1) decreases significantly with increasing the excitation energy under the collision free condition, while ΦF(S2) decreases only slightly. The pressure dependence of the fluorescence yields is interpreted in terms of the relaxation model involving the reversible internal conversion between S1 and S2 and the vibrational relaxation in the S1 manifold. The reverse S1 → S2 internal conversion rate is shown to be very slow compared with the forward S2 → S1 internal conversion rate. 相似文献
17.
An apparent difference between formulating mean field perturbation theory for λφ4 field theory via path integrals or via functional differential equations when there are external sources present is shown not to exist when mean field theory is considered as the N = 1 limit of the 0(N)λφ4 field theory. A simple method is given for determining the 1/N expansion for the Green's functions in the presence of external sources by directly solving the functional differential equations order by order in 1/N. The 1/N expansion for the effective action Γ(φ, χ) is obtained by directly integrating the functional differential equations for the fields φ and χ (
) in the presence of two external sources j = −δΓ/δφ, S = −δΓ/δχ. 相似文献
18.
Dian-Yong Chen Xiang Liu Xue-Qian Li 《The European Physical Journal C - Particles and Fields》2011,71(11):1808
To solve the discrepancy between the experimental data on the partial widths and lineshapes of the dipion emission of ϒ(4S) and the theoretical predictions, we suggest that there is an additional contribution, which had not been taken into account
in previous calculations. Noticing that the mass of ϒ(4S) is above the production threshold of B[`(B)]B\bar{B}, the contribution of the sequential process
\varUpsilon(4S)? B[`(B)]? \varUpsilon(nS)+S?\varUpsilon(nS)+p+p-\varUpsilon(4S)\to B\bar{B}\to \varUpsilon(nS)+S\to\varUpsilon(nS)+\pi^{+}\pi^{-} (n=1,2) may be sizable, and its interference with that from the direct production would be important. The goal of this work
is to investigate if a sum of the two contributions with a relative phase indeed reproduces the data. Our numerical results
on the partial widths and the lineshapes
d\varGamma(\varUpsilon(4S)?\varUpsilon(2S,1S)p+p-)/d(mp+p-)d\varGamma(\varUpsilon(4S)\to\varUpsilon(2S,1S)\pi^{+}\pi^{-})/d(m_{\pi ^{+}\pi^{-}}) are satisfactorily consistent with the measurements; thus the role of this mechanism is confirmed. Moreover, with the parameters
obtained by fitting the data of the Belle and BaBar collaborations, we predict the distributions dΓ(ϒ(4S)→ϒ(2S,1S)π
+
π
−)/dcosθ, which have not been measured yet. 相似文献
19.
S. Nagamiya 《Physics letters. [Part B]》1973,45(1):15-18
Magnetic moments of single-particle (or-hole) states around the 208Pb core were fitted by three state-independent parameters δgl(p), δgl(n) and α, where α is a parameter that is connected closely with δgS and gp. The analysis was performed under the assumptions that (i) the state-dependence of radial integral I((nl)2(n'l')2) involved in δgs and gp is calculated by the harmonic-oscillator potential, and (ii) δgs is taken as being equal to ?4gp, as expected from the δ-force type core polarization. An excellent fit was obtained when δgl(p) = 0.10(2), δgl(n) = ?0.05(1) and α = 1.2(1), which show that the main contributor to δgs is the M1 core polarization and δgl(n) is certainly smaller than 0. B(M1)'s for allowed transitions calculated with the use of the same parameters as above are smaller than the observed B(M1)'s whereas α = 1.01(1) explains well the observed B(M1)'s. 相似文献
20.
W. F. Mahmoudi N. Ben Nessib S. Sahal-Bréchot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):7-10
Owing to the increasing sensitivity of detectors,
accurate line profiles are needed for accurate stellar
atmospheres modelling and for laboratory and technological plasmas
as well. So, Stark broadening parameters of isolated lines of
complex atoms and ions within the impact and quasistatic
approximation are needed, even if the atomic abundance of the considered element is low.
Angular factors of the diagonal line strength entering the
quadrupole term appearing in the semi-classical expression of the
width of line broadened by electron or ion perturbers, are needed.
The aim of this paper is to extend the previous calculations of
this diagonal multiplet factor which were obtained for
configurations of the type ln and l1
nl2
m to
more complex configurations in LS coupling.
To study the Stark broadening of isolated lines in the impact and
quasistatic approximation, we use the semi-classical-perturbation
treatment, including both dipole and quadrupole contribution in
the expansion of the electrostatic interaction between the optical
electron and the perturber. We also use the Fano-Racah algebra.
Angular factors of the diagonal line strength entering the
quadrupole term appearing in the semi-classical expression of the
width of line broadened by electron or ion perturbers, are
calculated. New diagonal multiplet factor formulae for more
complicated configurations such as
(n1l1
n(LnSn)n2l2
m(LmSm)n3l3
p(LpSp))
are provided.
These formulae can enter the computer Stark semi-classical
perturbation codes. 相似文献