共查询到20条相似文献,搜索用时 31 毫秒
1.
We use a bag model to study flavoured mesonic (Qq
) and baryonic (
qqqq) states, where one heavy quarkQ is associated with light quarks or antiquarks, and search for possible stable multiquark states. No such bound state is found. However, some states lie not too high above their dissociation threshold, suggesting the possibility of resonances, or perhaps bound states in alternative models. 相似文献
2.
A. V. Sobolev 《Communications in Mathematical Physics》1993,156(1):101-126
We study a three-particle Schrödinger operatorH for which none of the two-particle subsystems has negative bound states and at least two of them have zero energy resonances. We prove that under this condition the numberN(z) of bound states ofH belowz<0 has the asymptotics
asz-0, where the coefficient
depends only on the ratio of masses of the particles. 相似文献
3.
Strongly self-dual Yang-Mills fields in even-dimensional spaces are characterised by a set of constraints on the eigenvalues of the Yang-Mills fieldsF
. We derive a topological bound on R8,
, wherep1 is the first Pontryagin class of the SO(n) Yang-Mills bundle, andk is a constant. Strongly self-dual Yang-Mills fields realise the lower bound. 相似文献
4.
Jan Philip Solovej 《Communications in Mathematical Physics》1990,130(1):185-204
We use the no-binding theorem of Thomas-Fermi theory to prove that a large diatomic molecule is almost neutral. That is to say, that if the total nuclear charge isZ then the numberN of electrons required for the diatomic molecule to be stable satisfies
. In contrast to the atomic case the emphasis here is on the lower bound onN. Our analysis will imply a new bound on the size of the molecule. These results are proved in the Born-Oppenheimer approximation. We also give bounds onN which hold for allZ by a very elementary method, not assuming the Born-Oppenheimer approximation.Work supported by a Danish Research Academy fellowship and U.S. National Science Foundation grant PHY-85-15288-A03Adress from September 1989: Department of Mathematics, The University of Michigan, Ann Arbor, Michigan 48109 USA 相似文献
5.
We consider a two-dimensional electron with an anomalous magnetic moment, g>2, interacting with a nonzero magnetic field B perpendicular to the plane which gives rise to a flux F. Recent results about the discrete spectrum of the Pauli operator are extended to fields with the
decay at infinity: we show that if
exceeds an integer N, there is at least
bound states. Furthermore, we prove that weakly coupled bound states exist under mild regularity assumptions also in the zero flux case. 相似文献
6.
We study the effects of light gluinos with
GeV on the nucleon parton densities and the running of
S
. It is shown that from the available high-statistics DIS data no lower bound on the gluino mass can be derived. Also in the new kinematical region accessible at HERA the influence of such light gluinos on structure functions is found to be very small and difficult to detect. For use in more direct searches involving final state signatures we present a radiative estimate of the gluino distribution in the nucleon.Work supported by the German Federal Ministry for Research and Technology under contract No. 05 6MU93P 相似文献
7.
Nils A. Törnqvist 《Zeitschrift fur Physik C Particles and Fields》1994,61(3):525-537
A systematic study of possible deuteronlike twomeson bound states,deusons, is presented. Previous arguments that many such bound states may exist are elaborated with detailed arguments and numerical calculations including, in particular, the tensor potential. This tensor potential which is crucial for the deuteron binding is shown to be very important also in the mesonic case. Especially, in the pseudoscalar3
P
0 pseudoscalar-vector
and vector-vector
channels the important observation is made that the centrifugal barrier from theP-wave can be overcome by the 1/r
2 and 1/r
3 terms of the tensor potential. In the heavy meson sector one-pion exchange alone is strong enough to form at least deuteronlike
and
composites bound by approximately 50 MeV. Composites of
and
states bound by pion exchange alone are expected near the thresholds, while in the light meson sector one generally needs some additional short range attraction to form bound states. The quantum numbers of these states areI=0, andJ
PC=0–+, 1++ for the
states andI=0,J
PC=0++, O–+, 1+– and 2++ for the
composites. In
the states:
b
(10545),
b1(10562) are predicted and in
, one finds the states:
b
(10590),
bQ
(10582),h
b(10608),
b2(10602). Near the
threshold the states:
c
(3870),
c0(3870) are predicted, and near the
threshold one finds the states:
b0(4015),
c
(4015),h
c(4015),
c2(4015). Within the light meson sector pion exchange gives strong attraction for
and
systems with quantum numbers where the best non-
candidates exist, although pion exchange alone is not strong enough to support such bound states. Thus, although one cannot conclude with certainty it to be the case, this fact does favour the picture that the (1440) and thef
1 (1420) are mainly
composites and thef
0(1710) mainly a
bound state, while thef
0(1515) andf
2(1520) could be predominantly
composites. If the predicted
and
states are found, these would support this interpretation of the light states. In channels with exotic flavour orCP quantum numbers pion exchange is generally repulsive or quite weak. Therefore one does not expect that such deuteronlike bound states exist, althoughB*B* may be an exception. 相似文献
8.
We investigate an infinite array of point interactions of the same strength in
d
, d = 2, 3, situated at vertices of a polygonal curve with a fixed edge length. We demonstrate that if the curve is not a line, but it is asymptotically straight in a suitable sense, the corresponding Hamiltonian has bound states. An example is given in which the number of these bound states can exceed any positive integer. 相似文献
9.
We prove the almost sure existence of a pure point spectrum for the two-dimensional Landau Hamiltonian with an unbounded Anderson-like random potential, provided that the magnetic field is sufficiently large. For these models, the probability distribution of the coupling constant is assumed to be absolutely continuous. The corresponding densityg has support equal to
, and satisfies
, for some > 0. This includes the case of Gaussian distributions. We show that the almost sure spectrum is
, provided the magnetic field B0. We prove that for each positive integer n, there exists a field strength B
n
, such that for all B>B
n
, the almost sure spectrum is pure point at all energies
except in intervals of width
about each lower Landau level
, for m < n. We also prove that for any B0, the integrated density of states is Lipschitz continuous away from the Landau energiesE
n
(B). This follows from a new Wegner estimate for the finite-area magnetic Hamiltonians with random potentials. 相似文献
10.
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
11.
I. M. Narodetskii Yu. A. Simonov V. P. Yurov 《Zeitschrift fur Physik C Particles and Fields》1992,55(4):695-700
Color-magnetic interaction with a smearing function found from the fit to the - splitting is strong enough to support a bound state of a single
pair. We present some piloting calculations in order to illustrate the eigenenergy dependence on the cutoff parameter for different choices of the smearing function. In the threequark system the spin-spin interaction can lead to the existence of the short-range correlations in each1
S
o
qq subsystem, thereby providing the dynamical mechanism for the quark-diquark picture of the proton. 相似文献
12.
P. Dita 《Communications in Mathematical Physics》1994,159(3):581-591
The parametrisation of ann×n unitary matrix by the moduli of its elements is not a well posed problem, i.e. there are continuous and discrete ambiguities which naturally appear. We show that the continuous ambiguity is (n–1)(n–3)-dimensional in the general case and
in the symmetric caseS
ij=Sij. We give also lower bounds on the number of discrete ambiguities, the number of solutions being at least
in the first case and
for the symmetric one, where [r] denotes the integral part ofr. 相似文献
13.
T. Nattermann M. Feigelman I. Lyuksyutov 《Zeitschrift für Physik B Condensed Matter》1991,84(3):353-359
We analyze the influence of thermal and frozen-in disorder on the flux line (FL) density
close to the lower critical fieldH
c1. Arguments which consider the steric repulsion of fluctuating FLs give
with the roughness exponent of a single FL andd the space dimensionality. We show by a phenomenological scaling approach and a renormalization group treatment, that this is correct only fordd
c
=2/–1, i.e. for
. Ford>d
c
the steric FL repulsion at scales more than some critical one is irrelevant and
. For disordered superconductorsd
c
=2 and
ford=2, 3. We also found the melting line for a FL lattice in the presence of frozen-in impurities close toH
c1. 相似文献
14.
We consider stochastic processes,
with
finite, in which spin flips (i.e., changes of S
t
x
) do not raise the energy. We extend earlier results of Nanda–Newman–Stein that each site x has almost surely only finitely many flips that strictly lower the energy and thus that in models without zero-energy flips there is convergence to an absorbing state. In particular, the assumption of finite mean energy density can be eliminated by constructing a percolation-theoretic Lyapunov function density as a substitute for the mean energy density. Our results apply to random energy functions with a translation-invariant distribution and to quite general (not necessarily Markovian) dynamics. 相似文献
15.
Given n2, we put r=min
. Let be a compact, C
r
-smooth surface in n which contains the origin. Let further
be a family of measurable subsets of such that
as
. We derive an asymptotic expansion for the discrete spectrum of the Schrödinger operator
in L
2(
n
), where is a positive constant, as
. An analogous result is given also for geometrically induced bound states due to a interaction supported by an infinite planar curve. 相似文献
16.
Suppose
g
is the (negative) Laplace–Beltrami operator of a Riemannian metric g on
n
which is Euclidean outside some compact set. It is known that the resolvent R()=(–
g
–2)–1, as the operator from L
2
comp(
n
) to H
2
loc(
n
), has a meromorphic extension from the lower half plane to the complex plane or the logarithmic plane when n is odd or even, respectively. Resonances are defined to be the poles of this meromorphic extension. We prove that when n is 4 or 6, there always exist infinitely many resonances provided that g is not flat. When n is greater than 6 and even, we prove the same result under the condition that the metric is conformally Euclidean or is close to the Euclidean metric. 相似文献
17.
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
18.
Finite dimensional representations of the quantum analog of the enveloping algebra of a complex simple Lie algebra 总被引:3,自引:0,他引:3
Marc Rosso 《Communications in Mathematical Physics》1988,117(4):581-593
Let
be a complex simple Lie algebra. We show that whent is not a root of 1 all finite dimensional representations of the quantum analogU
t
are completely reducible, and we classify the irreducible ones in terms of highest weights. In particular, they can be seen as deformations of the representations of the (classical)U
. 相似文献
19.
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
20.
Mauro Napsuciale 《Foundations of Physics》2003,33(5):741-768
In this work we review the derivation of Dirac and Weinberg equations based on a principle of indistinguishability for the (j,0) and (0,j) irreducible representations (irreps) of the homogeneous Lorentz group (HLG). We generalize this principle and explore its consequences for other irreps containing j1. We rederive Ahluwalia–Kirchbach equation using this principle and conclude that it yields
equations of motion for any representation containing spin j and lower spins. We also use the obtained generators of the HLG for a given representation to explore the possibility of the existence of first order equations for that representation. We show that, except for j=
, there exists no Dirac-like equation for the (j,0)(0,j) representation nor for the (
,
) representation. We rederive Kemmer–Duffin–Petieau (KDP) equation for the (1,0)(
,
)(0,1) representation by this method and show that the (1,
)(
,1) representation satisfies a Dirac-like equation which describes a multiplet of
with masses m and m/2, respectively. 相似文献