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1.
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
2.
The branching ratio of beauty hadrons to final states containing two charm hadrons, Br(b
, has been measured using an inclusive method in hadronic Z0 decays with the OPAL detector at LEP. The impact parameter significance of tracks opposite tagged b-jets is used to differentiate b
decays from other decays. The result is
where det. is the systematic uncertainty due to the modelling of the detector, and
is the systematic uncertainty due to the modelling of the underlying physics. Using this result, the average number of charm plus anti-charm quarks produced in a beauty quark decay, nc, is found to be 1.12 + 0.11-0.10.Received: 11 July 2003, Published online: 18 May 2004 相似文献
3.
On the Schrödinger equation and the eigenvalue problem 总被引:1,自引:0,他引:1
If
k
is thek
th eigenvalue for the Dirichlet boundary problem on a bounded domain in
n
, H. Weyl's asymptotic formula asserts that
, hence
. We prove that for any domain and for all
. A simple proof for the upper bound of the number of eigenvalues less than or equal to - for the operator –V(x) defined on
n
(n3) in terms of
is also provided.Research partially supported by a Sloan Fellowship and NSF Grant No. 81-07911-A1 相似文献
4.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2009,61(2):321-329
We calculate the masses and the pole residues of the
heavy baryons Ω
c
0(css) and Ω
b
−(bss) with the QCD sum rules. The numerical values
GeV (or
GeV) and
GeV (or
GeV) are in good agreement with the experimental data. 相似文献
5.
For a (co)monad T
l
on a category , an object X in , and a functor , there is a (co)simplex in . The aim of this paper is to find criteria for para-(co)cyclicity of Z
*. Our construction is built on a distributive law of T
l
with a second (co)monad T
r
on , a natural transformation , and a morphism in . The (symmetrical) relations i and w need to satisfy are categorical versions of Kaygun’s axioms of a transposition map. Motivation comes from the observation
that a (co)ring T over an algebra R determines a distributive law of two (co)monads and on the category of R-bimodules. The functor Π can be chosen such that is the cyclic R-module tensor product. A natural transformation is given by the flip map and a morphism is constructed whenever T is a (co)module algebra or coring of an R-bialgebroid. The notion of a stable anti-Yetter-Drinfel’d module over certain bialgebroids, the so-called ×
R
-Hopf algebras, is introduced. In the particular example when T is a module coring of a ×
R
-Hopf algebra and X is a stable anti-Yetter-Drinfel’d -module, the para-cyclic object Z
* is shown to project to a cyclic structure on . For a -Galois extension , a stable anti-Yetter-Drinfel’d -module T
S
is constructed, such that the cyclic objects and are isomorphic. This extends a theorem by Jara and Ştefan for Hopf Galois extensions. As an application, we compute Hochschild
and cyclic homologies of a groupoid with coefficients in a stable anti-Yetter-Drinfel’d module, by tracing it back to the
group case. In particular, we obtain explicit expressions for (coinciding relative and ordinary) Hochschild and cyclic homologies
of a groupoid. The latter extends results of Burghelea on cyclic homology of groups. 相似文献
6.
J. Bielcikova 《The European Physical Journal C - Particles and Fields》2005,43(1-4):323-327
A study of elliptic flow and two-particle azimuthal correlations of charged particles (
GeV/c) and high-
pions (
GeV/c) in Pb + Au collisions at 158A GeV/c, close to midrapidity, is presented. Elliptic flow (v
2) rises linearly with
to a value of about 10
at 2 GeV/c. Beyond
1.5 GeV/c, the slope decreases and possibly indicates a v
2 saturation at high
. Two-pion azimuthal anisotropies for
1.2 GeV/c exceed the v
2 values by about 60
in semicentral collisions. This non-flow component is attributed to near-side and away-side jetlike correlations. While the
near-side peak remains constant with centrality 0.23
0.03 rad, as expected for fragmentation, the away-side peak experiences broadening and disappears in central collisions.
Arrival of the final proofs: 30 June 2005
PACS:
25.75.Ld, 25.75.Gz 相似文献
7.
Horacio G. Rotstein Amy Novick-Cohen Rina Tannenbaum 《Journal of statistical physics》1998,90(1-2):119-143
Metallic cluster growth within a reactive polymer matrix is modeled by augmenting coagulation equations to include the influence of side reactions of metal atoms with the polymer matrix:
where > 0 and where c
k denotes the concentration of the kth cluster and p denotes the concentration of reactive sites available within the polymer matrix for reaction with metallic atoms. The initial conditions are required to be non-negative and satisfy
and p(0) = p
0. We assume that
for 01, which encompasses both bond linking kernels (R
jk
= j
k
) and surface reaction kernels (R
jk
= j
+ k
). Our analytical and numerical results indicate that the side reactions delay gelation in some cases and inhibit gelation in others. We provide numerical evidence that gelation occurs for the classical coagulation equations ( = 0) with the bond linking kernel (d ) for 1/2<1. We examine the relative fraction of metal atoms, which coagulate compared to those which interact with the polymer matrix, and demonstrate in particular a linear dependence on –1 in the limiting case R
= jk
, p
0=1. 相似文献
8.
A. H. Völkel 《Communications in Mathematical Physics》1966,2(1):176-214
By subtraction of products of three-point functions the four-point functions in relativistic quantum field theory are decomposed into two parts, in one of which there does not occur any mass-shell-singularity in the variables (; 1, 4). All these singularities are given explicitly by the kernels of the products of the three-point functions. — Necessary and sufficient conditions for the non-triviality of unitaryS-matrices or some of their elements are proved in terms of statements on the occurence of mass-shell-singularities in the vacuum expectation values of field operators. The strongest result we have gained is: If
is equal to zero for someN>3, then all transition amplitudesT
2n
vanish for everyn. 相似文献
9.
R. D. S. Yadava 《Zeitschrift für Physik B Condensed Matter》1992,86(1):93-99
An analysis of the ac conductivity ac(), and the ac dielectric constant, (), of the metal-insulator percolation systems is presented in the critical regime near the transition threshold. It is argued that the polarization and relaxation of the finite fractal metallic clusters play dominant roles in controlling the dynamic response of the system on both sides of the threshold. The relaxation time constant of a fractal cluster is shown to scale with its size as
withd
t
= 4 – 2d +d
c
+ /, whered is tge Euclidean dimension, andd
c
, , and are the scaling indices for the charging, the dc conductivity, and the correlation length respectively. The average time dependent response of the system is shown to scale with a new time scale
, where is the correlation length and 0 is a microscopic time constant. It is shown that at frequencies
and
with /dt 1, in close agreement with experiments. The effects of the anomalous transport along the infinite cluster and the medium polarizability are also discussed. 相似文献
10.
For a Lie algebra with Lie bracket got by taking commutators in a nonunital associative algebra
, let
be the vector space of tensors over
equipped with the Itô Hopf algebra structure derived from the associative multiplication in
. It is shown that a necessary and sufficient condition that the double product integral
satisfy the quantum Yang–Baxter equation over
is that
satisfy the same equation over the unital associative algebra
got by adjoining a unit element to
. In particular, the first-order coefficient r1 of r[h] satisfies the classical Yang–Baxter equation. Using the fact that the multiplicative inverse of
is
where
is the inverse of
in
we construct a quantisation of an arbitrary quasitriangular Lie bialgebra structure on
in the unital associative subalgebra of
consisting of formal power series whose zero order coefficient lies in the space
of symmetric tensors. The deformation coproduct acts on
by conjugating the undeformed coproduct by
and the coboundary structure r of
is given by
where
is the flip.Mathematical Subject Classification (2000). 53D55, 17B62 相似文献
11.
Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson
virtualities
. The data were taken at the ep collider HERA with centre-of-mass energy
using the ZEUS detector and correspond to an integrated luminosity of
. Jets were identified in the Breit frame using the kT cluster algorithm in the longitudinally invariant inclusive mode. Measurements of differential dijet and trijet cross sections
are presented as functions of jet transverse energy (
), pseudorapidity (
) and Q2 with
and
. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant
, determined from the ratio of the trijet to dijet cross sections, is
.
Received: 1 April 2005, Revised: 28 June 2005, Published online: 30 August 2005 相似文献
12.
We consider the Dirichlet Laplacian for astrip in
with one straight boundary and a width
, where $f$ is a smooth function of acompact support with a length 2b. We show that in the criticalcase,
, the operator has nobound statesfor small
.On the otherhand, a weakly bound state existsprovided
. In thatcase, there are positive c
1,c
2 suchthat the corresponding eigenvalue satisfies
for all
sufficiently small. 相似文献
13.
Measurements of the time-dependent CP-asymmetry in the decay
and its charge conjugate by the BELLE and BABAR collaborations currently yield
and
, characterizing the direct and mixing-induced CP-asymmetries, respectively. We study the implication of these measurements on the CKM phenomenology taking into account the available information in the quark mixing sector. Our analysis leads to the results that the ratio |P
c
/T
c
| involving the QCD-penguin and tree amplitudes and the related strong phase difference
in the
decays are quite substantial. Using the isospin symmetry to constrain |P
c
/T
c
| and
, where
parameterizes the penguin-induced contribution, we present a fit of the current data including the measurements of
and
. Our best-fits yield
,
,
,
, and
. At 68% C.L., the ranges are
,
,
,
and
. Currently en vogue dynamical approaches to estimate the hadronic matrix elements in
decays do not provide a good fit of the current data.Received: 5 April 2004, Published online: 14 July 2004A.Ya. Parkhomenko: On leave of absence from Department of Theoretical Physics, Yaroslavl State University, Sovietskaya 14, 150000 Yaroslavl, Russia. 相似文献
14.
Measurements of on-shell ZZ production are described, using data from the DELPHI experiment at LEP in e
+
e
- collisions at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 665 pb-1. Results obtained in each of the final states
,
,
,
,
, l
+
l
-
l
+
l
-, and
(with
) are presented. The measured production cross-sections are consistent with the Standard Model expectations. These results update and supersede those already published at 183 and 189 GeV.Received: 3 March 2002, Revised: 28 May 2003, Published online: 19 September 2003 相似文献
15.
Shao-Long Chen Xiao-Gang He Xue-Peng Hu Yi Liao 《The European Physical Journal C - Particles and Fields》2009,60(2):317-321
An unparticle
with scaling dimension
has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter
, the ratio of pressure to energy density, is given by
providing a new form of energy in our universe. In an expanding universe, the unparticle energy density
evolves dramatically differently from that for photons. For
, even if
at a high decoupling temperature T
D is very small, it is possible to have a large relic density
at present photon temperature T
γ
0, large enough to play the role of dark matter. We calculate T
D and
using photon–unparticle interactions for illustration. 相似文献
16.
R. F. Streater 《Communications in Mathematical Physics》1967,6(4):233-247
We consider a lattice of spin 1/2 ions, described by the discrete form of the current commutation relationsJ
i
J
(i)
=1/2, [J
i
,J
i
]=i
ij
J
i
where =1, 2, 3 andi label the lattice sites. The algebra is realized as the Clifford algebra
over a Hilbert space. The equations of motion are specified by a formal Hamiltonian of the Heisenberg form:
, wheref
ij
0 and only a finite numberQ of ions are linked to any given lattice site. We prove that the Hamiltonian is non-negative in a representation of
, and has a ground state exhibiting ferromagnetism. The time displacement group acts continuously on
, inducing automorphisms.
is asymptotically abelian with respect to the space translations of the lattice.The model is an example of an algebraic quantum field theory and possesses a broken symmetry, the rotation group 0(3). The consequent Goldstone theorem is proved, namely, there is no energy gap in the spectrum ofH. 相似文献
17.
18.
We extend a recent chiral approach to nuclear matter by including the most general (momentum-independent) NN-contact interaction. Iterating this two-parameter contact vertex with itself and with one-pion exchange the emerging energy per particle exhausts all terms possible up to and including fourth order in the small momentum expansion. Two (isospin-dependent) cut-offs
are introduced to regularize the (linear) divergences of some three-loop in-medium diagrams. The equation of state of pure neutron matter,
, can be reproduced very well up to quite high neutron densities of
by adjusting the strength of a repulsive nn-contact interaction. Binding and saturation of isospin-symmetric nuclear matter is a generic feature of our perturbative calculation. Fixing the maximum binding energy per particle to
MeV we find that any possible equilibrium density
lies below
. The additional constraint from the neutron matter equation of state leads however to a somewhat too low saturation density of
. We also investigate the effects of the NN-contact interaction on the complex single-particle potential U(p,k
f
) + i W(p,k
f
). We find that the effective nucleon mass at the Fermi surface is bounded from below by
. This property keeps the critical temperature of the liquid-gas phase transition at somewhat too high values
MeV. The downward bending of the asymmetry energy A(k
f
) above nuclear-matter saturation density is a generic feature of theapproximation to fourth order. We furthermore investigate the effects of the NN-contact interaction on the
-term in the nuclear energy density functional
. Altogether, there is within this complete fourth-order calculation no magic set of adjustable short-range parameters with which one could reproduce simultaneously and accurately all semi-empirical properties of nuclear matter. In particular, the conditions for a good neutron matter equation of state and for good single-particle properties are mutually exclusive.Received: 28 October 2003, Revised: 9 December 2003, Published online: 23 July 2004PACS:
12.38.Bx Perturbative calculations - 21.65. + f Nuclear matter - 24.10.Cn Many-body theory - 31.15.Ew Density-functional theory 相似文献
19.
Richard V. Kadison 《Communications in Mathematical Physics》1982,85(1):143-154
Estimates for vector representations of states are used to prove that {C
n
C
0} is strong-operator convergent toC
0, whereC
n is the universal central support of
n
and {
n
} is a sequence of states of aC*-algebra
converging in norm to 0. States of
of a given type are shown to form a norm-closed convex subset of the (norm) dual of
. The pure states of
form a norm-closed subset of the dual.With partial support of the National Science Foundation (USA) 相似文献
20.
K. Ravishankar 《Journal of statistical physics》1989,54(1-2):531-537
A sequence of i.i.d. matrix-valued random variables
with probabilityp and
with probability 1–p is considered. Leta() = a
0
+ O(), c() = c
0
+ O() lim
0
b() = Oa
0,c
0, >0, andb()>0 for all >0. It is shown show that the top Lyapunov exponent of the matrix productX
n
X
n-1...X
1, = limn (1/n) n X
n
X
n-1...X
1 satisfies a power law with an exponent 1/2. That is, lim 0(ln /ln ) = 1/2. 相似文献