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1.
Considerable efforts that have been undertaken in recent years in low-energy antineutrino experiments require further systematic
investigations in line of reactor antineutrino spectroscopy as a metrological basis of these experiments. We consider some
effects associated with the nonequilibrium of reactor
radiation and residual
emission from spent reactor fuel in contemporary
experiments.
The text was submitted by the authors in English. 相似文献
2.
A theory of weak localization responsible for the negative magnetoresistance effect is developed for quantum wells at the
tellurium surface, which retains, in contrast to the
surface considered earlier, a trigonal spectrum distortion with opposite signs near the M and P extrema, with the latter playing the part of states with opposite spins. It is shown that as a result of the motion in momentum
and spin spaces being correlated the spin relaxation due to this distortion is smaller than that for the (0001) surface.
Fiz. Tverd. Tela (St. Petersburg) 39, 1659–1664 (September 1997) 相似文献
3.
4.
Let
be the Haag--Kastler net generated by the
(2) chiral current algebra at level 1. We classify the SL(2,
)-covariant subsystems
by showing that they are all fixed points nets
H
for some subgroup H of the gauge automorphisms group SO(3) of
. Then, using the fact that the net
1 generated by the
(1) chiral current can be regarded as a subsystem of
, we classify the subsystems of
1. In this case, there are two distinct proper subsystems: the one generated by the energy-momentum tensor and the gauge invariant subsystem
. 相似文献
5.
G.Ya. Korenman 《Hyperfine Interactions》1999,119(1-4):227-233
Effect of medium density on shift and broadening of (
) spectral lines is considered in the framework of binary-collision approximation with an effective (
)–He potential including the long-range attraction and short-range repulsion. Quantum calculations of the scattering phase
shifts at reasonable values of the potential parameters allow to explain the main features of the observed density effect
on the shape of (
) spectral lines in low-temperature helium.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Given a simple, simply laced, complex Lie algebra
corresponding to the Lie group G, let
be thesubalgebra generated by the positive roots. In this Letter we construct aBV algebra
whose underlying graded commutative algebra is given by the cohomology, with respect to
, of the algebra of regular functions on G with values in
. We conjecture that
describes the algebra of allphysical (i.e., BRST invariant) operators of the noncritical
string. The conjecture is verified in the two explicitly known cases,
2 (the Virasoro string) and
3 (the
string). 相似文献
7.
The product of two real spectral triples
and
, the first of which is necessarily even, was defined by A.Connes as
given by
and, in the even-even case, by
. Generically it is assumed that the real structure
obeys the relations
,
,
, where the
-sign table depends on the dimension n modulo 8 of the spectral triple. If both spectral triples obey Connes'
>-sign table, it is seen that their product, defined in the straightforward way above, does not necessarily obey this
-sign table. In this Letter, we propose an alternative definition of the product real structure such that the
-sign table is also satisfied by the product. 相似文献
8.
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
9.
G. Dietz K. Richter F. Stein H. C. Schäfer 《Zeitschrift für Physik B Condensed Matter》1990,81(2):223-228
Dependent on
is produced through electrodeposition in three modifications: microcrystalline if
, amorphous if
and in a mixed state containing both components if
. The interpretation of results of large and small angle X-ray scattering, of measurements of the coercivity and of the mechanical density shows that the three modifications consist of two phases. The structure of the grain boundary phase in the microcrystalline alloys differs considerably from that of the amorphous phase. This arises from the dependence of the atomic volume on the average phosphorus content
. The volume fraction of the crystalline component decreases with increasing
up to
. But even in alloys revealing X-ray patterns without any peaks coming from crystalline particles small angle X-ray scattering indicates the existence of metal-rich inclusions occupying some percent of the total volume. 相似文献
10.
Michael Keyl 《International Journal of Theoretical Physics》1998,37(1):375-385
The major subject of algebraic quantum fieldtheory is the study of nets of local C*-algebras, i.e.,maps
(
) assigning to each open,relatively compact region of space-time (M, g) aC*-algebra
(
), whose self-adjoint elements describe localobservables measurable in the region
. A question discussed recently in a number ofpapers is how much information about the geometricstructure of the underlying space-time (M, g) is encoded in the algebraicstructure of the net
(
). Followingthese ideas, it is demonstrated in this paper howspace-time-related concepts like causality and observerscan be described in a purely algebraic way, i.e., using only thelocal algebras
(
).These results are then used to show how the space-time(M, g) can be reconstructed from the set
loc := {
(
)|
M open,
compact} of local algebras. 相似文献
11.
12.
Stefano De Leo Zbigniew Oziewicz Waldyr A. Rodrigues Jayme Vaz 《International Journal of Theoretical Physics》1999,38(9):2349-2369
We formulate the variational principle of theDirac equation within the noncommutative even space-timesubalgebra, the Clifford
-algebra
. A fundamental ingredient in ourmultivectorial algebraic formulation is a
-complex geometry,
. We derive the Lagrangian for theDirac-Hestenes equation and show that it must be mapped on
, where denotes an
-algebra of functions. 相似文献
13.
Let
be von Neumann algebras acting on a Hilbert space
and let
be a common cyclic and separating vector. We say that
have the modular intersection property with respect to
if(1)
-half-sided modular inclusions,(2)
(If (1) holds the strong limit exists.) We show that under these conditions the modular groups of
and
generate a 2-dim. Lie group.This observation is the basis for obtaining group representations of Sl(2,
)/Z
2 generated by modular groups. 相似文献
14.
A simplified construction of representations is presented for the quantized enveloping algebra
q (
), with
being a simple complex Lie algebra belonging to one of the four principal series A\ell, B\ell, C\ell or D\ell. The carrier representation space is the quantized algebra of polynomials in antiholomorphic coordinate functions on the big cell of a coadjoint orbit of K where K is the compact simple Lie group with the Lie algebra
– the compact form of
. 相似文献
15.
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
16.
Leonid I. Men'shikov 《Hyperfine Interactions》1999,119(1-4):245-250
A new interpretation of the nature of the metastable states of antiprotons in helium is proposed. The first step is the formation
of an ion (
), which shall be called “ioncule”. After its decay a neutral “atomcule” (
) is formed which was observed in the experiments on metastable antiprotonic helium. This model explains the experiments in
a natural way, in particular the quenching by atomic and molecular admixtures and the pressure dependence of quenching in
pure helium. At high helium densities the ioncule creates a vacuum bubble in helium. It is shown that the annihilation of
slowed-down
can be suppressed at helium pressures of ∼ 10 000 bar.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
The CPT Group of the Dirac Field 总被引:2,自引:2,他引:0
Miguel Socolovsky 《International Journal of Theoretical Physics》2004,43(9):1941-1967
Using the standard representation of the Dirac equation, we show that, up to signs, there exist only two sets of consistent solutions for the matrices of charge conjugation (C), parity (P), and time reversal (T), which give the transformation of fields
,
and
, where
and
. These sets are given by
,
,
and
,
,
. Then
, and two successive applications of the parity transformation to fermion fields necessarily amount to a 2 rotation. Each of these sets generates a non abelian group of 16 elements, respectively,
and
, which are non isomorphic subgroups of the Dirac algebra, which, being a Clifford algebra, gives a geometric nature to the generators, in particular to charge conjugation. It turns out that
and
, where
is the dihedral group of eight elements, the group of symmetries of the square, and 16E is a non trivial extension of
by
, isomorphic to a semidirect product of these groups; S6 and S8 are the symmetric groups of six and eight elements. The matrices are also given in the Weyl representation, suitable for taking the massless limit, and in the Majorana representation, describing self-conjugate fields. Instead, the quantum operators C, P and T, acting on the Hilbert space, generate a unique group
, which we call the CPT group of the Dirac field. This group, however, is compatible only with the second of the above two matrix solutions, namely with
, which is then called the matrix CPT group. It turns out that
, where
is the dicyclic group of 8 elements and S10 is the symmetric group of 10 elements. Since
, the quaternion group, and
, the 0-sphere, then
. 相似文献
18.
We use the recursion method to calculate the vibrational density of states
of site percolation clusters slightly above the percolation threshold. It is found that
is proportional to at long wavelengths. At shorter length scales,
is proportional to
, with the fraction dimension
. The cross-over from phonon to fraction regime is characterized by a rapid rise in
in agreement with effective medium calculations. 相似文献
19.
A. T. Kozakov V. V. Kolesnikov A. V. Nikol’skii V. P. Sakhnenko 《Physics of the Solid State》1997,39(4):594-597
Anomalous electron emission from the
surface of LiNbO3 and LiTaO3 single crystals excited by soft x radiation has been discovered and is investigated. The absence of anomalous emission from
the
face of these single crystals is established. The experimental results confirm the theoretical conclusions that the anomalous
emission is caused by the presence of a maximum in the distribution of the potential in the near-surface layer. The dependence
of the lifetime τ of the anomalous emission on the dielectric constant ɛ of the ferroelectric is calculated.
Fiz. Tverd. Tela (St. Petersburg) 39, 679–682 (April 1997) 相似文献
20.
G.L. Borchert D. Anagnostopoulos M. Augsburger D. Belmiloud C. Castelli D. Chatellard M. Daum J.P. Egger P. El-Khoury M. Elble R. Frosch H. Gorke D. Gotta P. Hauser P. Indelicato K. Kirch S. Lenz N. Nelms K. Rashid O.W.B. Schult Th. Siems L.M. Simons 《Hyperfine Interactions》1998,114(1-4):157-164
Some time after its formation an exotic atom may be considered a hydrogen-like system consisting of a nucleus and an exotic
particle in a bound state. In this situation it is an ideal tool to study cascade properties, while for the innermost orbits
it can be used to probe the interaction with the nucleus. From an extended series of experiments using high resolution X-ray
spectroscopy for both aspects typical examples are reported and preliminary results are given: 1. To determine the complex
scattering length in
H the
hyperfine transitions have been measured. 2. To determine the pion mass the 5
4 transitions in
N have been studied. In all cases a major contribution to the uncertainty originates from the calibration. Therefore a new
method is proposed that will establish a universal set of high precision calibration lines for pionic, muonic and electronic
systems.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献