共查询到20条相似文献,搜索用时 31 毫秒
1.
By using the second-order moment of the power density, the beam width, far-field divergence angle and M2 factor of nonparaxial truncated flattened Gaussian (FG) beams are derived analytically. It is shown that the M2 factor of nonparaxial truncated FG beams depends not only on the truncation parameter δ and beam order N, but also on the initial waist-width to wavelength ratio w0/λ. The far-field divergence angle approaches an asymptotic value of θmax=63.435° when the truncation parameter δ → 0. For the special cases of N = 0 and δ → ∞ our results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated FG beams, respectively. 相似文献
2.
Q.-M. Nie W. Zhou Q.-H. Chen 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(4):485-489
The non-equilibrium phase transitions of the fullyfrustrated (f = 1/2) square lattice Coulomb gas (CG) modeldriven by external
electrical fields are studied in the frameworkof the short-time dynamic scaling approach. The criticaltemperature Tc, the static and dynamic critical exponents2β/ν, ν, and z are obtained for several smalldriving fields. The results show that
Tc decreases with theincrease of electric field, and 2β/ν and z arestrongly dependent on the external electric field. Interestingly,contrary
to the equilibrium case, in the presence of smallelectric field, the calculated exponent ν is close to that inpure 2D Ising
model, which provides numerical evidence thatexternal electric field may change the universality class of thef = 1/2 CG system. 相似文献
3.
Mixing angles of η and η′ mesons are obtained in the scheme of octet-singlet mixing θη = −15.4°, θ′η = −17.9°, and in the scheme connected with expansion in the quark basis $
\bar q
$
\bar q
q − $
\bar s
$
\bar s
s φ = 39.3°. The constants gV
ηγ, g
η′
V
γ of radiative decays η′ → V
γ and V → ηγ (V ≡ ρ, ω, φ) and the ratios of constants of weak decays of η and η′ mesons are calculated. The numerical values that were found
are in agreement with the experimental data. 相似文献
4.
S. V. Yablonskii A. S. Mikhailov S. P. Palto S. G. Yudin S. V. Yakovlev G. Durand 《JETP Letters》1998,67(6):409-415
We have developed a new method for measuring tilt bias angles in spatially uniform and nonuniform thin films of nematic liquid
crystals. The method employs modulation ellipsometry, based on the use of an exponentially decaying light wave to probe the
boundary layer. Oscillations of the director of the liquid crystal, which are induced by the flexoelectric torque, are excited
with an external periodic field. A periodic variation of the ellipticity of the light wave reflected from the interface is
detected at both the first and second harmonics of the exciting electric field. When these two Fourier components of the electrooptic
response are known, it is possible to calculate both the tilt bias angle θ0 of the director and the dynamic deviation δ0 of the tilt bias angle. The angles θ0 and δ0 measured by this method on the surface of an electrode (ITO) and on the surface of a ferroelectric film (a copolymer of vinylidene
fluoride and trifluoroethylene), oriented in a corona discharge, were equal to θ 0=5.1°, δθ=0.5° and θ0=89°, δθ=0.06°, respectively.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 6, 387–392 (25 March 1998) 相似文献
5.
The effects of final-state interactions (FSI) in hadronic B decays are investigated. The model for FSI, based on Regge phenomenology of high-energy hadronic interactions, is proposed.
It is shown that this model explains the pattern of phases in matrix elements of B → ππ and B → ρρ decays. These phases play an important role for CP violation in B decays. The most precise determination of the unitarity triangle angle α from B
d
→ ρπ decays is performed. The relation between CP asymmetries in B → Kπ decays is discussed. It is emphasized that the large-distance FSI can explain the structure of polarizations of the vector
mesons in B decays and other puzzles like a very large branching ratio of the B decay to $
\bar \Xi
$
\bar \Xi
c
Λ
c
. 相似文献
6.
K. Uzelac Z. Glumac O. S. Barišić 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(1):101-108
We present numerical investigations of the short-time dynamics at criticality in the 1D Potts model with power-law decaying
interactions of the form 1/r1+σ. The scaling properties of the magnetization, autocorrelation function and time correlations of the magnetization are studied.
The dynamical critical exponents θ' and z are derived in the cases q=2 and q=3 for several values of the parameter σ belonging
to the nontrivial critical regime. 相似文献
7.
C. Aydın M. Bayar A.H. Yılmaz 《The European Physical Journal C - Particles and Fields》2006,48(1):111-115
We present a calculation of the coupling constant of f0→ργ and a0→ργ decays from the point of view of the light cone QCD sum rules. We estimate the coupling constants gf0ργ, which are an essential ingredient in the analysis of physical processes involving the isoscalar f0(980) and the isovector a0(980) mesons. PACS 12.38.Lg, 13.40.Hq, 14.40.AqAn erratum to this article can be found at 相似文献
8.
We discuss the high density behavior of a system of hard spheres of diameter d on the hypercubic lattice of dimension n, in the limit n→∞, d→∞, d/n = δ. The problem is relevant for coding theory, and the best available bounds state that the maximum density of the system falls in the interval 1 ≤ ρ V
d
≤ exp (n κ(δ)), being κ(δ) > 0 and V
d
the volume of a sphere of radius d. We find a solution of the equations describing the liquid up to an exponentially large value of ρ = ρ V
d
, but we show that this solution gives a negative entropy for the liquid phase for ρ >rsimn. We then conjecture that a phase transition towards a different phase might take place, and we discuss possible scenarios for this transition.
PACS: 05.20.Jj, 64.70.Pf, 61.20.Gy 相似文献
9.
L. Zhang G. Tang Z. Xun K. Han H. Chen B. Hu 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(2):227-234
The long-wavelength properties of the (d + 1)-dimensional
Kuramoto-Sivashinsky (KS) equation with both conservative and nonconservative
noises are investigated by use of the dynamic renormalization-group (DRG)
theory. The dynamic exponent z and roughness exponent α are
calculated for substrate dimensions d = 1 and d = 2, respectively. In the
case of d = 1, we arrive at the critical exponents z = 1.5 and α = 0.5
, which are consistent with the results obtained by Ueno et al. in the
discussion of the same noisy KS equation in 1+1 dimensions [Phys. Rev. E 71,
046138 (2005)] and are believed to be identical with the dynamic scaling of
the Kardar-Parisi-Zhang (KPZ) in 1+1 dimensions. In the case of d = 2, we
find a fixed point with the dynamic exponents z = 2.866 and α = -0.866
, which show that, as in the 1 + 1 dimensions situation, the existence of
the conservative noise in 2 + 1 or higher dimensional KS equation can also
lead to new fixed points with different dynamic scaling exponents. In
addition, since a higher order approximation is adopted, our calculations in
this paper have improved the results obtained previously by Cuerno and
Lauritsen [Phys. Rev. E 52, 4853 (1995)] in the DRG analysis of the noisy KS
equation, where the conservative noise is not taken into account. 相似文献
10.
We present an analytic perturbative method for calculatingf(α) and the generalized dimensionD
q
of the critical invariant circle of the polynomial circle map. The scaling behaviour is found to depend onz, the exponent defining the map. The asymptotic bounds of the scaling constantsα(z) andδ(z) are verified analytically. 相似文献
11.
Zhen-Jun Xiao Xin-Fen Chen Dong-Qin Guo 《The European Physical Journal C - Particles and Fields》2007,50(2):363-371
In this paper, we calculate the branching ratios and CP-violating asymmetries for Bs→ρ±K∓, ρ0K̄0 and ωK̄0 decays in the perturbative QCD factorization approach. The theoretical predictions for the CP-averaged branching ratios of
the considered decays are Br(Bs→ρ±K∓)≈24.7×10-6, Br(Bs→ρ0K̄0)≈1.2×10-7 and Br(Bs→ωK̄0)≈1.7×10-7; and we also predict large CP-violating asymmetries for the considered decay modes. Specifically, the large ACP
dir(Bs→ρ±K∓) at -12% level plus large branching ratio at 10-5 level are measurable in the forthcoming LHC-b experiments.
PACS 13.25.Hw; 12.38.Bx; 14.40.Nd 相似文献
12.
C. Michael 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):793-798
I review the lattice QCD approach to determining hadronic-decay transitions. Examples considered include ρ→ππ; b
1→πω; hybrid meson decays and scalar meson decays. I discuss what lattices can provide to help understand the composition of hadrons. 相似文献
13.
A. Donini D. Meloni S. Rigolin 《The European Physical Journal C - Particles and Fields》2006,45(1):73-95
We present in this paper the analysis of the measurement of the unknown PMNS parameters θ13 and δ at future LBL facilities performing complete three parameters fits, each time fully including in the fit one of the
atmospheric and solar oscillation parameters within its present (future) error. We show that, due to the presence of degeneracies,
present uncertainties on θ23 and
worsen significantly the precision on (θ13,δ) at future LBL experiments. Only if a precision on the atmospheric parameters at least similar to what expected at T2K-I
is reached, then the sensitivities to θ13 and δ that have been presented in the literature for many facilities (where θ23 and
are generally considered as fixed external inputs) can indeed be almost recovered. On the other hand, the impact on this
measurement of the uncertainties on the solar parameters, θ12 and
is already negligible. Our analysis has been performed using three reference setups: the SPL Super-Beam and the standard
low-γ β-Beam, both aiming toward a Mton Water Čerenkov detector located at L = 130 km; the 50 GeV Neutrino Factory with a 40 kton Magnetized Iron Detector to look for the "golden channel" νe → νμ with baseline L = 3000 km and a 4 kton Emulsion Cloud Chamber to look for the "silver channel" νe → ντ with baseline L = 732 km.
Received: 19 July 2005, Revised: 30 September 2005, Published online: 11 November 2005
PACS:
14.60.Pq, 14.60.Lm 相似文献
14.
The two-dimensional dilute granular flow on a smooth incline bounded by rough sidewalls is investigated experimentally, and
the transverse density profiles of granular flux (ζ = ρ v) across the channel are measured. The results show that the transverse density profiles of granular flux are symmetric about
the channel center and that the density of granular flux near the boundary is clearly lower than that of the center. There
is a critical width of channel W
c for the transition of the density of granular flux. The density of granular flux near the boundary decays with the increasing
of inclination (sinθ) of the channel.
Supported by the National Natural Science Foundation of China (Grant No. 10274071) and the Department of Education of Zhejiang
Province (Grant Nos. 20050916 and y200804093) 相似文献
15.
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
16.
Federico Camia Luiz Renato G. Fontes Charles M. Newman 《Journal of statistical physics》2006,125(5-6):1155-1171
We analyze the geometry of scaling limits of near-critical 2D percolation, i.e., for p = p
c+λδ1/ν, with ν = 4/3, as the lattice spacing δ → 0. Our proposed framework extends previous analyses for p = p
c, based on SLE
6. It combines the continuum nonsimple loop process describing the full scaling limit at criticality with a Poissonian process
for marking double (touching) points of that (critical) loop process. The double points are exactly the continuum limits of
“macroscopically pivotal” lattice sites and the marked ones are those that actually change state as λ varies. This structure
is rich enough to yield a one-parameter family of near-critical loop processes and their associated connectivity probabilities
as well as related processes describing, e.g., the scaling limit of 2D minimal spanning trees. 相似文献
17.
β-γ-γ directional correlation studies for the cascades (i)β-rays ofE
max=0.12 MeV,γ-rays of 557 keV andγ-rays of 53 keV and (ii)β-rays ofE
max=0.21 MeV,γ-rays of 444 keV andγ-rays of 53 keV have been made. The triple correlation functionsW(θ) were obtained to beW(θ)=1+(−0.153±0.031)P
2(cosθ)+(0.004±0.035)P
4(cosθ) forβ-rays ofE
max 0.12 MeV→557→53 keV cascade andW(θ)=1+(0.163±0.042)P
2(cosθ)+(−0.035±0.058)P
4(cosθ) forβ rays ofE
max=0.21 MeV→444 keV→53 keV cascade.
Spins and parities of the 650, 537 and 93 keV levels of103Rh are deduced by triple angular correlation and the internal conversion coefficient studies. Multipolarities of the transitions
are also determined. 相似文献
18.
We study different types of radiative decays involving f0(980) and a0(980) mesons within a unified ChPT-based approach at one-loop level. Light scalar resonances, which are seen in the ππ, πη
and KK̄ channels of the φ(1020) radiative decays and in the J/ψ decays are responsible for key questions of low-energy dynamics
in the strong interaction sector, and the decays φ(1020)→γa0(980), φ(1020)→γf0(980), a0(980)→γγ and f0(980)→γγ are of interest for current experimental programs in Jülich, Frascati and Novosibirsk. From the theoretical point
of view it is important to verify whether light scalar mesons are members of some flavor octet or nonet. We find a value for
the mixing angle dictated by consistency with experiment and the coupling structures of the ChPT Lagrangian. The decay widths
f0(980)/a0(980)→γρ(770)/ω(782), which have not been experimentally studied yet, are predicted. We also obtain several relations between
the widths, which hold independently of the coupling constants and which represent a fingerprint of the model.
PACS 11.30.Hv; 12.39.Fe; 13.30.Eg; 14.40.-n 相似文献
19.
Y.C. Shin M.K. Cheoun K.S. Kim T.K. Choi 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):87-93
A role of the axial-vector mesons, such as K1 and a1, on the emitted-photon spectrum in hot hadronic matter is studied through the channels πρ→a
1→πγ and Kρ→K
1→Kγ. Both channels could be dominant over the region lower than E
γ∼ 0.5 GeV, while the role of the K1 meson is diminished in the higher E
γ region. This study is carried out with an SU
L(3) ⊗SU
R(3) effective chiral Lagrangian which includes vector and axial-vector mesons systematically and explains well their hadronic
and radiative decays simultaneously.
Received: 8 August 2001 / Accepted: 4 February 2002 相似文献
20.
T Padmanabhan 《Pramana》1991,36(3):253-269
The quantisation of a charged scalar field in an externally specified electromagnetic field, described by the vector potentialA
i=∂if withf(t,r,θ,z)=Bθ is discussed. The electromagnetic field is zero everywhere except at the origin; a singular magnetic field (Aharonov-Bohm
field) exists at the origin. The vacuum polarization around such a magnetic field is computed and the non-local behaviour
is discussed. 相似文献