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1.
The maximum number of non-vanishing and independent second order photoelastic coefficients required by the seven pentagonal
and the two icosahedral point groups 5(C5),
(S10),
(C5h
),
m2(D5h
), 52(D5), 5m(C5v
),
2m(D5d
); 235(I), 2/m
(I
h
)—that describe the quasicrystals symmetry groups in two and three dimensions—is obtained. The schemes of non-vanishing and
independent coefficients have been calculated and listed. Finally the results of this group-theoretical study are briefly
discussed. 相似文献
2.
KN sigma commutator has been calculated in the framework of the (6,
)+(
, 6) model. It is found that though this model could not be discarded in favour of the (3,
)+(
, 3) or (8, 8) model, a very large value forKN sigma term is required to get a positive value ofπN sigma term. 相似文献
3.
An estimation of the mass difference of
system with heavy quark symmetry formalism is presented. The effective Hamiltonian describing the transition
(whereh=b forB
d
0
-system) is considered in a manifest left right symmetric (MLRS) model along with contribution from neutral Higgs boson. We
use the spin and flavor symmetry for heavy quarks to obtain the transition matrix element 〈B
d
0
|ℋeff(x)|
d
0
〉 in terms of Isgur-Wise function. Assuming thatB
d
0
and
states are at rest, we find that Isgur-Wise function turns out to be unity. However using the experimental values of ΔM
K and
as input, we find thatM
R=835 GeV andM
H⩾2·9 TeV. 相似文献
4.
Gyan Mohan 《Pramana》1983,21(3):201-206
That the longlived componentL ofK
0 has bothcp=+1 andcp=−1 modes of decay is often cited as evidence of violation ofcp invariance. The careful ones find the compelling evidence to be the non-dilution of the regeneration interference pattern
when the incidentK
0 beam is mixed even substantially with
. However the two phenomena comprehensively imply thatL has acp=+1 componentL
+ and acp=−1 componentL
− and that the longlived component of bothK
0 and
are one and the sameL. This does not demand abandoningcp invariance. It does imply that
is not thecp conjugate ofK
0. 相似文献
5.
Explicit evaluation of the following parameters has been carried out in the extraU (1) superstring inspired model: (i) As Mz2 varies from 555 GeV to 620 GeV and (m
t) CDF = 175.6 ± 5.7 GeV (Table 1): (a) SNew varies from -0.100 ± 0.089 to -0.130 ± 0.090, (b) TNew varies from -0.098 ± 0.097 to -0.129 ± 0.098, (c) UNew varies from -0.229 ± 0.177 to -0.253 ± 0.206, (d) Τz varies from 2.487 ± 0.027 to 2.486 ± 0.027, (e) ALR varies from 0.0125 ± 0.0003 to 0.0126 ± 0.0003, (f) A
FB
b
remains constant at 0.0080 ± 0.0007. Almost identical values are obtained for (m
t)D0 = 169 GeV (see table 2). (ii) Triple gauge boson vertices (TGV) contributions: AsMz
2 varies from 555 GeV to 620 GeV and (m
t) CDF = 175.6 ±5.7 GeV. (a)√s = 500 GeV, asymptotic case:
varies from -0.301 to -0.179;
varies from -0.622 to -0.379;
varies from +0.0061 to 0.0056;
varies from -3.691 to -2.186.
varies from +0.270 to +0.118;
varies from +0.552 to 0.238;
varies from +0.0004 to +0.0002;
remains constant at -0.110. (b)√s = 700 GeV, asymptotic case:
varies from -0.297 to -0.176;
varies from -0.609 to -0.370;
varies from -0.0082 to -0.0078;
varies from -3.680 to -2.171.√s = 700 GeV, nonasymptotic case:
varies from -0.173 to -0.299;
varies from-0.343 to -0.591;
varies from -0.005 to -0.011;
remains constant at -0.110.
The pattern of form factors values for√s = 1000, 1200 GeV is almost identical to that of√s= 700 GeV. Further the values of the form factors for (m
t)D0 (=169 GeV) follow identical pattern as that of (m
t) CDF form factors values (see tables 5, 6, 9, 10).
We conclude that the values of all the form factors with the exception of these of
,
are comparable or larger than theS, T values and therefore the TGV contributions are important while deciding the use of extraU (1) model for doing physics beyond standard model. 相似文献
6.
Gely F. Zharkov 《Central European Journal of Physics》2005,3(1):77-103
Self-consistent solutions of the nonlinear Ginzburg-Landau (GL) equations are investigated numerically for a superconducting
(SC) cylinder, placed in an axial magnetic field, with a single vortex on the axis (m=1). Two modes, which show the original state of the cylinder, SC or normal (s
0 andn
0), are studied. The field increase (FI) and the field decrease (FD) regimes are studied. The critical fields destroying the
SC state withm=1 are found in both regimes. It is shown that in a cylinder of radiusR and GL-parameter ϰ, there exist a number of solutions depending only on the radial co-ordinater corresponding to different states such as M,e, d, p,i, n,
,n
*, and the state diagram on the plane of the variables (ϰ,R) is described. The critical fields corresponding to intrastate transitions and the onset of hysteresis are obtained. The
critical fieldH
0(R) dividing the paramagnetic and diamagnetic states of the cylinder withm=1 is determined. The limiting fields of supercooling or superheating of the normal state at which the restoration of the
SC state occurs are established. It is shown, that (in both casesm=1,0) there exist two critical parameters,
and
, which divide bulk SC into three groups (with
and
), in accordance with the behavior in a magnetic field. The parameters
and
mark the boundary for the existence of a supercooled normal
-state in FD-regime and a superheated SC M-state in FI-regime respectively. It is shown, that the value
, which was claimed in a number of papers as related to type-I superconductors, is illusory.
We regret to inform that Professor Gely Zharkov passed away on 9th July 2004. 相似文献
7.
Ola Bratteli 《Letters in Mathematical Physics》1982,6(6):499-504
Let δ be a quasi-free derivation of the CAR algebra, and let
be a closed *-derivation which is an extension of δ. We use Price's techniques from [6] to show that if the polynomials in
the linear field operators a(f)→a
*
(f) in D(
) is a core for
, then
is quasi-free. 相似文献
8.
Recentcern
collider data on anomalousZ° events suggest, among other possibilities, a composite structure for the weak intermediate vector bosons. We present a short
review of these developments and examine how far the scenario for weak interactions with such composite models of the weak
vector bosons presents a viable alternative to the standard electroweak theory. In particular, we show how the scale of the
dynamics underlying the composite structure is set by the magnitude of the weak mixing angle sin2
θ
w and point out the possibility of accommodating the anomalous
decay events presently observed within this picture. 相似文献
9.
Cross-sections for production of evaporation residues from the compound nucleus96Ru* formed by fusion reactions28Si+68Zn,32S+64Ni,37Cl+59Co and45Sc+51V have been obtained from the yields of their characteristicγ-rays. The measurements span an excitation energy range of 55 MeV to 70 MeV of the compound nucleus. The evaporation residue
(ER) cross-sections have been analysed in terms of statistical model for the decay of the compound nucleus. A good agreement
is found between statistical model calculation and the experimental evaporation residue cross-sections in all the four cases.
It is shown that the average angular momentum
of the compound nucleus can be deduced from a comparison of the experimentally measured and the statistical model predictions
for the ER cross-sections. The validity of this method of deriving
has been discussed for the case of16O+154Sm system. 相似文献
10.
A K Rajagopal 《Pramana》1992,38(3):233-247
We first draw attention to the fact that the position operator,
, its translation generator,
, and its scale generator,
, form an important group of triplet of operators that appear in the Heisenberg uncertainty relation stated in its most general
form. The pair
forms the phase-space and they have led to Fourier transform pair, the autocorrelation function, the Wiener-Khinchine theorem,
and the Wigner function with many different applications to wave phenomena. The importance of the pairs
and
has been pointed out by Moses and Quesada (1972, 1973, 1974) who showed that we must then consider a Mellin transform pair,
a scale autocorrelation function, and a corresponding Wiener-Khinchine theorem. In the present paper, we define and explore
properties of a bivariate averaging function defined in a new “phase-space” involving the Mellin transform variable and its
partner which can either be the position or momentum, analogous to the Wigner function. The not-necessarily positive feature
of the bivariate averaging functions is traced to the general Heisenberg uncertainty mentioned above. The properties and their
inter-relationships among the averaging functions are given. We hope this will be of use in discussing physical phenomena
involving fractals, turbulence, and near phase transitions where the scaling properties are of importance. 相似文献
11.
By using Kikkawa’s method the equivalence of the nonrenormalizable pair interaction
to a renormalizable theory is proved. Equivalence relationships between a few other nonrenormalizable and renormalizable
interactions are also indicated. 相似文献
12.
We discuss the behavior of magnetically trapped antihydrogen (
) at temperatures relevant for gravity and spectroscopy experiments (well below 1 K) and the possibilities of attaining these
temperatures. Two possible options are considered. In the discussion of the first one, i.e.
as admixture in cold H gas, we develop the quantum-mechanical theory of
-H (and also
-H) elastic and rearrangement collisions at ultra-low (sub-Kelvin) energies, when s-wave scattering in the incoming channel
dominates. The rate constant of rearrangement leading to
decay turns out to be large, which makes the possibilities for
collisional cooling in H gas and
-H coexistence rather limited. As we show, the most promising is the other option, i.e.
atoms in the collisionless regime. For this regime the possibility of one-dimensional adiabatic cooling of
is demonstrated by using the example of the Ioffe trap. This phenomenon, interesting from the fundamental point of view,
offers the opportunity to cool
below 1 mK. 相似文献
13.
Bragg cut-off for
plane of polycrystalline beryllium of various lengths of 300 and 116 K has been measured with an energy resolution of 5 μeV.
The natural width of the cut-off is 12.5±1.5 μeV, independent of temperature and length of beryllium and also of physical
characteristics and certain metallurgical treatments of the powder. Such blocks of beryllium would be suitable for designing
a ΔT-window spectrometer with resolution ⩾20 μeV. Bragg cut-offs corresponding to (0002) and
planes of beryllium have been separated for the first time. These can also be used for producing additional energy windows
in a ΔT-window spectrometer, thus increasing its efficiency.
Paper entitled ‘ΔT-window spectrometer’ will appear in the November issue of Pramana. 相似文献
14.
Pin-Zhen Bi 《Zeitschrift fur Physik C Particles and Fields》1991,52(1):105-109
The ellipsoidal bag model is used to describe heavy quark systems such asQ
,Q
g andQ
2
. Instead of two step model, these states are described by an uniform picture. The potential derived from the ellipsoidal bag forQ
is almost equivalent to the Cornell potential. For aQ
2
system with large quark pair separation, an improvement of 70 MeV is obtained comparing with the spherical bag. 相似文献
15.
A. M. Ermolaev 《Hyperfine Interactions》1989,44(1-4):375-386
Partial and total close-coupled semiclassical (impact parameter) cross sections and total classical Monte-Carlo cross sections
for interactions in
and
, p+H collisions are computed in the intermediate keV range for antiprotons,
, up to 100 keV lab. Total cross sections for antihydrogen,
, formation are found to be large, 10−20×10−16 cm2 in a wider energy range than was anticipated earlier, up to some 20 keV lab. New estimates of cross sections for ionisation
of atomic hydrogen by antiproton impact are reported for the low-energy range 1–30 keV lab where they are 10−20×10−17 cm2, being much larger than the corresponding cross sections for ionisation of hydrogen by proton impact. Data for excitation
of H by
impact is also presented. 相似文献
16.
Decio Cocolicchio 《Foundations of Physics Letters》1990,3(4):359-365
A bound on theK
oscillating parameter has been obtained by some models of nonlocality. In this paper we stress the fact that aø factory to test the CP-violating parameters in theK system can also probe, through correlated observations of two
0, the incompatibility between the quantum mechanics and these formulations of the local realism. 相似文献
17.
A. E. Dorokhov N. I. Kochelev Yu. A. Zubov 《Zeitschrift fur Physik C Particles and Fields》1995,65(4):667-679
The spectrum of
, Jp=0+, 2+ mesons is discussed. We have shown that due to instanton-induced forces the physical states are strong mixtures of theSU
f
(3) group basis states. The cross-sections for annihilation of the
system into
mesons are obtained. Thea
0(980) meson is considered as
meson consisting of 9
f
and 36
f
plets. The branchings are also predicted for the cross-sections for production of thea
0(980) and tensor
mesons in
annihilation. 相似文献
18.
A heavy quark antiquark potential is suggested connecting asymptotic freedom and quark confinement in a unified way. Theα
g
(q
2) calculated using Borel summation technique with three loop agrees with the two loopβ-function up tog
2/4π≅ 1.1 but changes appreciably afterg
2/4π=1.5. The potential so derived satisfactorily explains the
and
spectrum. 相似文献
19.
We examine the effects of mixing induced non-diagonal light-heavy neutrino weak neutral currents on the amplitude for the
process
(with a=e, μ or τ). By imposing constraint that the amplitude should not exceed the perturbative unitarity limit at high energy
, we obtain bounds on light-heavy neutrino mixing parameter sin2
where
is the mixing angle. In the case of one heavy neutrino (mass mξ) or mass degenerate heavy neutrinos, for Λ=1 TeV, no bound is obtained for mξ<0.50 TeV. However, sin2
≤3.8 × 10−6 for mξ=5 TeV and sin
≤6.0 × 10−8 for mξ=10 TeV. For Λ=∞, no constraint is obtained for mξ<0.99 TeV and sin2
≤3.8 × 10−2 (for mξ=5 TeV) and sin2
≤9.6 × 10−3 (for mξ=10 TeV). 相似文献
20.
Defining the ratiosr
p
=σ(vp →vx)/σ(vp →μ
−
x) and
we obtain the bounds 0.28 ⩽r
p
⩽ 0.61 and
using only the parton model and the data of CDHS group with iron target. We also give the complete set of parton-model relations
which would allow the determination of all the neutral-current coupling constants from inclusive cross sections alone. 相似文献