共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
T.Yu. Tretyakova D.E. Lanskoy 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):391-398
Properties of light neutron-rich Λ hypernuclei (16
ΛC, 12
ΛBe, and 11
ΛLi) are calculated within the Skyrme-Hartree-Fock approach. Interplay between hypernuclear interaction features and properties
of these hypernuclei is studied. Response of weakly bound neutron states to hyperon addition depends generally on core distortion
by hyperon, and it is essentially different for the different states. This response is especially sensitive to details of
the ΛN interaction for 1p
1/2 states. Implications of the nuclear spin-orbit potential and nuclear incompressibility in the neutron-rich system properties
are inferred. Dependence of the Λ binding energies in hypernuclei on Z at fixed A is discussed.
Received: 16 December 1998 相似文献
3.
We use the non-perturbative Q$
\bar Q
$
\bar Q
potential at finite temperatures derived in the Field Correlator Method to obtain binding energies for the lowest eigenstates
in the Q$
\bar Q
$
\bar Q
and QQQ systems (Q = c, b). The three-quark problem is solved by the hyperspherical method. The solution provides an estimate of the melting temperature
and the radii for the different diquark and triquark bound states. In particular we find that J/ψ and ccc ground states survive up to T − 1.3T
c
, where T
c
is the critical temperature, while the corresponding bottomonium states survive even up to higher temperature, T − 2.3T
c
. 相似文献
4.
A. Valcarce H. Garcilazo J. Vijande 《The European Physical Journal A - Hadrons and Nuclei》2008,37(2):217-225
The recent observation at CDF and D0 of Σ
b
, Σ
b
* and Ξ
b
baryons opens the door to the advent of new states in the bottom baryon sector. The states measured provide sufficient constraints
to fix the parameters of phenomenological models. One may therefore consistently predict the full bottom baryon spectra. For
this purpose we have solved exactly the three-quark problem by means of the Faddeev method in momentum space. We consider
our guidance may help experimentalists in the search for new bottom baryons and their findings will help in constraining further
the phenomenological models. We identify particular states whose masses may allow to discriminate between the dynamics for
the light quark pairs predicted by different phenomenological models. Within the same framework we also present results for
charmed, doubly charmed, and doubly bottom baryons. Our results provide a restricted possible assignment of quantum numbers
to recently reported charmed-baryon states. Some of them are perfectly described by D-wave excitations with J
P
= 5/2+, as the Λ
c
(2880), Λ
c
(3055), and Λ
c
(3123).
Communicated by V. Vento 相似文献
5.
Jeong Ryeol Choi 《International Journal of Theoretical Physics》2006,45(1):176-196
We showed that the idea of Schleich and Wheeler (1987, Nature 326, 574) for the semiclassical approach of the interference in phase space of harmonic oscillator squeezed states can be extended to that of general time-dependent Hamiltonian system. The quantum phase properties of squeezed states for the general time-dependent Hamiltonian system are investigated by using the quantum distribution function. The weighted overlaps A
n
and phases θ
n
for the system are evaluated in the semiclassical limit. 相似文献
6.
7.
We present results for the helicity amplitudes of the lowest-lying hyperon resonances Y*, computed within the framework of the Bonn Constituent-Quark model, which is based on the Bethe-Salpeter approach. The seven
parameters entering the model were fitted to the best-known baryon masses. Accordingly, the results for the helicity amplitudes
are genuine predictions. Some hyperon resonances are seen to couple more strongly to a virtual photon with finite Q2 than to a real photon. Other Y*'s, such as the S01(1670) Λ-resonance or the S11(1620) Σ-resonance, couple very strongly to real photons. We present a qualitative argument for predicting the behaviour of
the helicity asymmetries of baryon resonances at high Q2.-1 相似文献
8.
9.
Bound states and critical behavior of the Yukawa potential 总被引:1,自引:0,他引:1
We investigate the bound states of the Yukawa potential V (r)=−λexp(−αr)/r, using different algorithms: solving the Schr?dinger equation numerically and our Monte Carlo Hamiltonian approach. There
is a critical α = αC, above which no bound state exists. We study the relation between αC and λ for various angular momentum quantum number l, and find in atomic units, αC(l) = λ[A
1 exp(−l/B
1) + A
2 exp(−l/B
2)], with A
1 = 1.020(18), B
1 = 0.443(14), A
2 = 0.170(17), and B
2 = 2.490(180). 相似文献
10.
A. Derevianko W. R. Johnson V. D. Ovsyannikov V. G. Pal’chikov D. R. Plante G. von Oppen 《Journal of Experimental and Theoretical Physics》1999,88(2):272-277
We use the relativistic configuration-interaction method and the model potential method to calculate the scalar and tensor
components of the dipole polarizabilities for the excited states 1s3p
3
P
0 and 1s3p
3
P
2 of the helium atom. The calculations of the reduced matrix elements for the resonant terms in the spectral expansion of the
polarizabilities are derived using two-electron basis functions of the relativistic Hamiltonian of the atom, a Hamiltonian
that incorporates the Coulomb and Breit electron-electron interactions. We formulate a new approach to determining the parameters
of the Fuss model potential. Finally, we show that the polarizability values are sensitive to the choice of the wave functions
used in the calculations.
Zh. éksp. Teor. Fiz. 115, 494–504 (February 1999) 相似文献
11.
In the framework of a simple spin-boson Hamiltonian we study an interplay between dynamic and spectral roots to stochastic-like
behavior. The Hamiltonian describes an initial vibrational state coupled to discrete dense spectrum reservoir. The reservoir
states are formed by three sequences with rationally independent periodicities 1; 1 ± δ typical for vibrational states in
many nanosize systems (e.g., large molecules containing CH2 fragment chains, or carbon nanotubes). We show that quantum evolution of the system is determined by a dimensionless parameter
δΓ, where Γ is characteristic number of the reservoir states relevant for the initial vibrational level dynamics. When δΓ
> 1 spectral chaos destroys recurrence cycles and the system state evolution is stochastic-like. In the opposite limit δΓ
< 1 dynamics is regular up to the critical recurrence cycle k
c
and for larger k > k
c
dynamic mixing leads to quasi-stochastic time evolution. Our semi-quantitative analytic results are confirmed by numerical
solution of the equation of motion. We anticipate that both kinds of stochastic-like behavior (namely, due to spectral mixing
and recurrence cycle dynamic mixing) can be observed by femtosecond spectroscopy methods in nanosystems in the spectral window
1011–1013 s−1 相似文献
12.
V.?Dmitra?inovi? Toru?Sato Milovan??uvakov 《The European Physical Journal C - Particles and Fields》2009,62(2):383-397
We calculate the energies of three-quark states with definite permutation symmetry (i.e. of SU(6) multiplets) in the N=0, 1, 2 shells, confined by the Y-string three-quark potential. The exact Y-string potential consists of one term, the so-called
three-string term, and three angle-dependent two-string terms. Due to this technical complication we treat the problem at
three increasingly accurate levels of approximation: (1) the (approximate) three-string potential expanded to first order
in trigonometric functions of hyper-spherical angles; (2) the (approximate) three-string potential to all orders in the power
expansion in hyper-spherical harmonics, but without taking into account the transition(s) to two-string potentials; (3) the
exact minimal-length string potential to all orders in a power expansion in the hyper-spherical harmonics, and taking into
account the transition(s) to two-string potentials. We show the general trend of improvement of these approximations: the
exact non-perturbative corrections to the total energy are of the order of one per cent, as compared with approximation (2),
yet the exact energy differences between the [20,1+],[70,2+],[56,2+],[70,0+]-plets are shifted to 2:2:0.9, from the Bowler and Tynemouth separation rule 2:2:1, which is obeyed by approximation (2)
at the one per cent level. The precise value of the energy separation of the first radial excitation (“Roper”) [56′,0+]-plet from the [70,1−]-plet depends on the approximation, but does not become negative, i.e. the “Roper” remains heavier than the odd-parity [70,1−]-plet in all of our approximations. 相似文献
13.
Nils Dalarsson 《International Journal of Theoretical Physics》1996,35(4):819-837
We suggest a quantum stabilization method for theSU(2) σ-model, based on the constant-cutoff limit of the cutoff quantization method developed by Balakrishnaet al., which avoids the difficulties with the usual soliton boundary conditions pointed out by Iwasaki and Ohyama. We investigate
the baryon numberB = 1 sector of the model and show that after the collective coordinate quantization it admits a stable soliton solution which
depends on a single dimensional arbitrary constant. We then study strong and electromagnetic properties of the Λ(1405) hyperon
in the bound-state approach to theSU(3)-soliton model for the hyperons, withSU(3)-symmetry breaking. We calculate the strong coupling constantg
Λ*NK;
, the magnetic moment of Λ*, the mean square radii, and the radiative decay amplitudes. Finally we compare the present results
with those obtained using other models and with the available empirical data. We show that there is a general qualitative
agreement between our results and the results of other models and available empirical data, except for the Λ*πΣ coupling,
which, as in the case of the complete Skyrme model, vanishes in the second-order approximation of the kaon fluctuations used
in this work. 相似文献
14.
The highly excited vibrational states of asymmetric linear tetratomic molecules are studied in the framework of Lie algebra.
By using symmetric groupU
1(4)U
2(4)⊗U
3(4), we construct the Hamiltonian that includes not only Casimir operators but also Majorana operators M12, M13 and M23, which are useful for getting potential energy surface and force constants in Lie algebra method. By Lie algebra treatment,
we obtain the eigenvalues of the Hamiltonian, and make the concrete calculation for molecule C2HF. 相似文献
15.
Current researches have shown that perfect states transfer over arbitrary distances is possible for a simple unmodulated spin
chain by some schemes. The transfer of a single qubit state has been investigated in detail by Christandl et al. [Phys. Rev. Lett. 92, 187902(2004)] through a modified Heisenberg XX model Hamiltonian H
G
. The previous study of Christandl is restricted to the first-excitation states of H
G
(i.e., which correspond to the second subspace of the Hilbert space of H
G
). In this work, we extend their study to the case of the high-excitation states, and find that the entangled states in such
a form, | ψ 〉 = α | 00⋯ 0〉 + β | 11⋯ 1〉, can be perfectly transfered on the spin chain.
PACS numbers 03.67.Hk, 03.67.Pp, 05.50.+q. 相似文献
16.
The Hamiltonian of the trigonometric Calogero–Sutherland model coincides with a certain limit of the Hamiltonian of the elliptic
Calogero–Moser model. In other words the elliptic Hamiltonian is a perturbed operator of the trigonometric one.
In this article we show the essential self-adjointness of the Hamiltonian of the elliptic Calogero–Moser model and the regularity
(convergence) of the perturbation for the arbitrary root system.
We also show the holomorphy of the joint eigenfunctions of the commuting Hamiltonians w.r.t the variables (x
1, …,x
N
) for the A
N
-1-case. As a result, the algebraic calculation of the perturbation is justified.
Received: 30 May 2001 / Accepted: 27 November 2001 相似文献
17.
A. A. Klochikhin S. A. Permogorov A. N. Reznitskii 《Journal of Experimental and Theoretical Physics》1999,88(3):574-585
We propose an approach to describing the density of fluctuation states in a disordered solid solution with a strong perturbation
introduced by isoelectronic substitution in the range of attraction-center concentrations below the threshold of percolation
along the sites of a disordered sublattice. To estimate the number of localized states we use the results of lattice percolation
theory. We describe a method for distinguishing, within the continuum percolation theory, among the various “radiating” states
of the fluctuation-induced tail, states that form the luminescence band at weak excitation. We also establish the position
of the band of radiating states in relation to the absorption band of the excitonic ground state and the mobility edge of
the system. The approach is used to describe the optical spectra of the solid solution ZnSe1−c
Tec, which at low Te concentrations can be interpreted as a system with strong scattering. We take into account the exciton-phonon
interaction and show that the calculated and observed luminescence spectra of localized excitons are in good agreement with
each other.
Zh. éksp. Teor. Fiz. 115, 1039–1062 (March 1999) 相似文献
18.
D. PortesJr. H. Rodrigues S. B. Duarte B. Baseia 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):145-149
We study the exchange of states in coupled fields along their time
evolution. The coupling is described by a quadratic form in terms of
annihilation and creation operator in the field Hamiltonian. An analytical
approach is employed to describe the time evolution of the field state in
Fock's space and the conditions for an arbitrary initial states to be
transferred with 100% fidelity is determined. We show that only for initial
states C0|0>+CN|N>, this situation can occurs. The important
|1〉↔|0〉 qubits transfer is a particular
case of this transference of number state. The relation between the coupling
constant and characteristic field frequencies for complete state
transference is also determined. 相似文献
19.
Ramazan Koc 《Czechoslovak Journal of Physics》2005,55(9):1135-1140
An approximate method is suggested to obtain analytical expressions for the eigenvalues and eigenfunctions of the some quantum
optical models. The method is based on the Lie-type transformation of the Hamiltonians. In a particular case it is demonstrated
that E × ɛ Jahn-Teller Hamiltonian can easily be solved within the framework of the suggested approximation. The method presented
here is conceptually simple and can easily be extended to the other quantum optical models. We also show that for a purely
imaginary coupling the E × ɛ Hamiltonian becomes non-Hermitian but Pσ0-symmetric. Possible generalization of this approach is outlined.
Presented at the 3rd International Workshop “Pseudo-Hermitian Hamiltonians in Quantum Physics”, Istanbul, Turkey, June 20–22,
2005. 相似文献
20.
A conventional wisdom often perpetuated in the literature states that: (i) a 3 + 1 decomposition of spacetime into space and
time is synonymous with the canonical treatment and this decomposition is essential for any Hamiltonian formulation of General
Relativity (GR); (ii) the canonical treatment unavoidably breaks the symmetry between space and time in GR and the resulting
algebra of constraints is not the algebra of four-dimensional diffeomorphism; (iii) according to some authors this algebra
allows one to derive only spatial diffeomorphism or, according to others, a specific field-dependent and non-covariant four-dimensional
diffeomorphism; (iv) the analyses of Dirac [21] and of ADM [22] of the canonical structure of GR are equivalent. We provide
some general reasons why these statements should be questioned. Points (i–iii) have been shown to be incorrect in [45] and
now we thoroughly re-examine all steps of the Dirac Hamiltonian formulation of GR. By direct calculation we show that Dirac’s
references to space-like surfaces are inessential and that such surfaces do not enter his calculations. In addition, we show
that his assumption g
0k
= 0, used to simplify his calculation of different contributions to the secondary constraints, is unwarranted; yet, remarkably
his total Hamiltonian is equivalent to the one computed without the assumption g
0k
= 0. The secondary constraints resulting from the conservation of the primary constraints of Dirac are in fact different
from the original constraints that Dirac called secondary (also known as the “Hamiltonian” and “diffeomorphism” constraints).
The Dirac constraints are instead particular combinations of the constraints which follow directly from the primary constraints.
Taking this difference into account we found, using two standard methods, that the generator of the gauge transformation gives
diffeomorphism invariance in four-dimensional space-time; and this shows that points (i–iii) above cannot be attributed to
the Dirac Hamiltonian formulation of GR. We also demonstrate that ADM and Dirac formulations are related by a transformation
of phase-space variables from the metric g
μν to lapse and shift functions and the three-metric g
km
, which is not canonical. This proves that point (iv) is incorrect. Points (i–iii) are mere consequences of using a non-canonical
change of variables and are not an intrinsic property of either the Hamilton-Dirac approach to constrained systems or Einstein’s
theory itself. 相似文献