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1.
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
2.
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
3.
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
4.
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
5.
Mohammad Sami 《Pramana》1982,18(5):451-460
The associated production of Higgs particles andZ (W) bosons inpp and
collisions is studied. The total cross-section of the processpp
→HXl
+
l
− is estimated. 相似文献
6.
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
7.
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
8.
Satish D Joglekar 《Pramana》1989,32(3):195-207
We discuss the general theory of renormalization of unbroken gauge theories in the nonlinear gauges in which the gauge-fixing
term is of the form
We show that higher loop renormalization modifiesfα [A] to contain ghost terms of the form
and show how the corresponding ghost terms are deduced fromfα [A, c, c] uniquely. We show that the theory can be renormalized while preserving a modified form of BRS invariance by multiplicative
and independent renormalizations onA, c, g, η, ζ, τ. We briefly discuss the independence of the renormalized S-matrix from η,ζ, τ. 相似文献
9.
I. A. Andreyev 《Technical Physics》2006,51(1):121-125
The variation of the resonance frequency of piezoelectric resonators subjected to a constant electric field is demonstrated
with longitudinal vibrations in La3Ga5SiO14 (langasite) crystal rods at temperatures between −60 and +80°C. For the rods whose longtudinal axis makes angle α with the
crystal axis
in the plane of the axes
and [0001], the change in the frequency is proportional to the field strength and depends on α. For a field of ±1.5 × 106 V/m and α = 15°, the relative change in the frequency is ±120 × 10−6. It is shown that La3Ga5SiO14 crystals offer a set of physical parameters that makes them promising for electrically controlled acoustoelectronic devices
and for devices based on nonlinear interaction between acoustic waves. 相似文献
10.
CP-violating rate asymmetry can be generated in a process only if its amplitude possesses an absorptive part. It is pointed
out that such an absorptive part can be provided ine
+
e
− annihilation by the presence of aZ(Z′) resonance of non-zero width. The CP asymmetry in the process
, wherel
i
are charged leptons, is discussed in several models. In a specific two-Z model, large and observable CP asymmetry ine
+
e
− →τ
+
e
− (τ
−
e
+) is shown to be possible at LEP/SLC energies. 相似文献
11.
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
12.
We show that the Grassmannian independence of the super-Lagrangian density, expressed in terms of the superfields defined
on a (4,2)-dimensional supermanifold, is a clear-cut proof for the Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST invariance
of the corresponding four (3+1)-dimensional (4D) Lagrangian density that describes the interaction between the U(1) gauge field and the charged complex scalar fields. The above 4D field theoretical model is considered on a (4,2)-dimensional
supermanifold parametrized by the ordinary four space-time variables x
μ (with μ = 0, 1, 2, 3) and a pair of Grassmannian variables θ and (with θ
2 =
2 = 0, θ
+
θ = 0). Geometrically, the (anti-)BRST invariance is encoded in the translation of the super-Lagrangian density along the Grassmannian
directions of the above supermanifold such that the outcome of this shift operation is zero.
相似文献
13.
Saurabh D Rindani 《Pramana》1995,45(Z1):263-276
The prospects of experimental detection ofCP violation ate
+
e
− and
colliders are reviewed. After a general discussion on the quantities which can measureCP violation and on the implications of theCPT theorem, various possibilities of measuringCP violation arising outside the standard model are taken up.CP violation in leptonic processes, especially polarization effects ine
+
e
−→l
+
l
− are discussed next.CP violation in
andW
+
W
− production and decay is also described. 相似文献
14.
(001)YBa2Cu3O7−δ
epitaxial films were prepared by laser ablation on
surface. A thin (001)CeO2 or (111)CeO2 buffer layer was deposited between the substrate and the superconductor film to reduce their chemical interaction. In the
initial stages of CeO2 buffer formation, its orientation depended strongly on the intensity of cerium ion interaction with oxygen. Epitaxial growth
of (001)YBa2Cu3O7−δ
films was achieved both on
and
. The T
c temperature of epitaxial (001)YBa2Cu3O7−δ
films was within 88–90 K, and the current J
c at 77 K was in excess of 106 A/cm−2.
Fiz. Tverd. Tela (St. Petersburg) 40, 205–208 (February 1998) 相似文献
15.
Using the Wigner-Kirkwood expansion and bare Lennard-Jones (LJ) (12-6) potential, an effectiveLJ potential is derived, which includes the quantum effects through the expressions of the effective diameter∂(T, λ) and well-depth
(T, λ). We use theWCA perturbation theory to calculate the free energy and pressure for theLJ and effectiveLJ potentials. Simple analytic expressions are given for the reference system and the first order correction calculated. The
results are quite good at high density. The quantum effects on the free energy and pressure are also discussed. 相似文献
16.
Summary The crystal size in accretions grown in an icing wind tunnel at ambient temperatures −18≥T
a
≥−27°C and different substrate temperatureT
s
<0°C is studied. For constantT
s
the mean area
of crystal sections shows an approximately exponential dependence onT
a
which may be written as
, where ΔT≃−T
a
represents the droplet supercooling. On the other hand, for fixedT
a
, the crystal size is observed to decrease markedly withT
s
. By considering previous results on the orientation of crystals forming the accretions, it is shown that the value of the
mean angle
formed by the crystalc-axis with the growth direction depends as well both onT
a
andT
s
. The exponential dependence of
andT
a
and the observed correspondence between the behaviour of
and
are correlated with a nucleation mechanism, accompanied by a process of orientation selection, which would be responsible
of both the crystal size and the orientation. The application of the crystal structure analysis to the determination of the
growth conditions of hailstones is discussed.
To speed up publication, the authors of this paper has agreed to not receive the proofs for correction.
Comisión Nacional de Energía Atómica and Consejo Nacional de Investigaciones Científicas y Técnicas. 相似文献
Riassunto Si studia la dimensione di un cristallo in accrezioni cresciute in una galleria a vento congelante a temperature ambienti −18≥T a ≥−27 °C e diversa temperatura di substratoT s <0 °C. PerT s costante, l’area media delle sezioni di cristallo mostra una dipendenza daT a approssimativamente esponenziale che potrebbe essere scritta così: , dove ΔT≃−T a rappresenta il superraffreddamento della gocciolina. D’altra parte, perT a fisso, si osserva che la dimensione del cristallo decresce marcatamente conT s . Considerando precedenti risultati sull’orientamento dei cristalli che formano le accrezioni, si mostra che anche il valore dell’angolo medio formato dall’assec del cristallo con la direzione di accrescimento dipende sia daT a che daT s . La dipendenza esponenziale di daT a e la corrispondenza osservata tra il comportamento di e di sono collegate con il meccanismo di nucleazione, accompagnato da un processo di selezione dell’orientamento, che dovrebbe essere responsabile sia della dimensione che dell’orientamento del cristallo. Si discute l’applicazione dell’analisi della struttura del cristallo alla determinzione delle condizioni di accrescimento dei chicchi di grandine.
To speed up publication, the authors of this paper has agreed to not receive the proofs for correction.
Comisión Nacional de Energía Atómica and Consejo Nacional de Investigaciones Científicas y Técnicas. 相似文献
17.
Saurabh D Rindani 《Pramana》2002,58(4):575-590
QCD corrections to order α
s
in the soft-gluon approximation to angular distributions of decay charged leptons in the process e
+
e
− → t
, followed by semileptonic decay of t
, are obtained in the esu− e
− centre-of-mass frame. As compared to distributions in the top rest frame, these have the advantage that they would allow
direct comparison with experiment without the need to reconstruct the top rest frame. The results also do not depend on the
choice of a spin quantization axis for t or t. Analytic expression for the triple distribution in the polar angle of t and polar and azimuthal angles of the lepton is obtained. Analytic expression is also derived for the distribution in the
charged-lepton polar angle. Numerical values are discussed for √s=400, 800 and 1500 GeV. 相似文献
18.
O. M. Boyarkin 《Russian Physics Journal》1996,39(6):597-600
The solar neutrino problem is considered within the framework of a model based on the gauge group SU(2)L×SU(2)R×U(1)B−L. An evolutionary equation is found for the eight-component wave function
and a scheme for possible resonant transitions is determined with allowance for the Majorana nature of the neutrino. The
influence of solar flares on the oscillation pattern of the neutrino flux is investigated.
Yankya Kupala State University, Grodno. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 116–120,
June, 1996. 相似文献
19.
The effect of impurities on the growth of manganese carbonate crystals has been studied. Stereophotogrammetric analysis showed
that all crystal faces have the same Miller indices
and the peanut-shaped forms are twins with twin axis 0001. 相似文献
20.
Weak decay modes (1/2+ → 3/2+ + 0−/γ) of charmed baryons are studied. Relations among the various decay amplitudes are derived in isospin, SU(3), SU(4) and
SU(8)
w
symmetries. Sextet dominance in SU(3) forbidsB(3) →D(10) +P(3*) decays. 20″ dominance in SU(4) specifies all the decays in terms of Θ− decays. Weak decays of Θ*
3
++
and Θ− are also discussed. SU(8)
w
symmetry predictsα
, which is consistent with the experimental value. 相似文献