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1.
In the framework of relativistic harmonic confinement model for quarks and antiquarks, the masses of S- and P-wave mesons and pseudoscalar decay constants from light flavour to heavy flavour sectors are computed. The residual two-body
Coulomb interaction and the spin-dependent interaction of the confined one gluon exchange effects (COGEP) such as spin-spin
and spin-orbit interactions are perturbatively incorporated with the confinement energy to get the respective vector-pseudoscalar
meson mass differences. Here we employ the same parametrization and model parameters as used in a recent study of low-lying
hadron masses and leptonic decay widths. The results are being compared with the values obtained from other theoretical models
and the experimental values. 相似文献
2.
A spin-dependent interaction in hadrons is considered in the approach of the QCD string. The string moment of inertia, which
ensures the correct (inverse) Regge slope 2πσ, is found to suppress the spin-orbit interaction. For light quarks and moderate
angular momenta, the suppression constitutes around 25%, whereas for large angular momenta the spin-orbit interaction is suppressed
by the factor L
−2/5. For heavy quarks, the effect manifests itself as a string correction for the spin-dependent potential.
The text was submitted by the authors in English. 相似文献
3.
A model of a lattice gas is considered in which molecules interact via three kinds of forces: short-ranged intra-molecular magnetic (producing a net magnetic moment per particle), long-ranged magnetic between those moments and finally long-ranged non-magnetic. Using the molecular field approximation for both kinds of the long-ranged forces and calculating exactly the contribution from the short-ranged interactions, we construct and discuss phase diagrams for the system. We show that the location of the (multi-) critical points is quite sensitive to the strength and/or sign of the intra-molecular interaction, as well as to the form of the molecules. 相似文献
4.
S. S. Gershtein V. V. Kiselev A. K. Likhoded A. I. Onishchenko 《Physics of Atomic Nuclei》2000,63(2):274-286
Within a nonrelativistic quark model featuring a QCD-motivated Buchmüller-Tye potential, the mass spectra for the families of doubly heavy baryons are calculated by assuming the quark-diquark structure of the baryon wave functions and by taking into account spin-dependent splitting. Physically motivated evidence that, in the case where heavy quarks have identical flavors, quasistationary excited states may be formed in the heavy-diquark subsystem is analyzed. 相似文献
5.
《Physics letters. [Part B]》1988,214(2):229-236
It is shown that forward matrix elements of j5μ, the flavor singlet axial vector current, do not merely measure the helicity carried by quarks and antiquarks but also include a spin-dependent gluonic component due to the anomaly. In perturbation theory the exact value of the gluonic component depends on the infrared regulator, and we argue that computing off-shell matrix elements with zero-mass quarks gives the proper method of regulation to exhibit the chiral properties of the theory. We suggest measuring two-jet production in deep inelastic scattering off polarized targets as a means of determining the spin-dependent gluonic component of j5μ. 相似文献
6.
A. Majethiya B. Patel P. C. Vinodkumar 《The European Physical Journal A - Hadrons and Nuclei》2008,38(3):307-315
Properties of single heavy flavor baryons in a non-relativistic potential model with colour Coulomb plus a power law confinement
potential have been studied using a simple variational method. The ground-state masses of single heavy baryons and the mass
difference between the J
P =
+ and J
P =
+ states are computed using a spin-dependent two-body potential. Using the spin-flavour structure of the constituting quarks
and by defining an effective confined mass of the constituent quarks within the baryons, the magnetic moments are computed.
The masses and magnetic moments of the single heavy baryons are found to be in accordance with the existing experimental values
and with other theoretical predictions. It is found that an additional attractive interaction of the order of -200 MeV is
required for the antisymmetric states of (Q
c, b) . It is also found that the spin-hyperfine interaction parameters play a decisive role in hadron spectroscopy. 相似文献
7.
George L. Strobel 《International Journal of Theoretical Physics》2003,42(3):523-529
The J = (3/2) , J = 1/2 Nucleon mass difference shows the quark energies can be spin dependent. It is natural to expect that the quark wave functions also depend on spin. A spin-dependent quark force is fitted to the proton and neutron magnetic moments, axial charge, and spin content using a (1/2+)3 configuration for the quarks and assuming only zero mass u and d quarks are in the nucleon. In the octet, such spin-dependent forces lead to different wave functions for quarks with spin parallel or antiparallel to the nucleon spin. The eigen-energy of this potential is 0.15 GeV higher for quark spin parallel than for the quark spin antiparallel to the proton spin. This potential predicts a single quark energy of 0.37 GeV for mass-less quarks in the Delta. Assuming the quark forces are flavor independent, this potential predicts magnetic moments of a bound strange quark to be very close to those determined empirically from the octet magnetic moments. 相似文献
8.
YANG Xin-E 《中国物理C(英文版)》1985,9(5):537-541
We propose a composite model of leptons and quarks containing two constituent fermions of spin 1/2 and a constituent scalar. The constituent fermions are massless and color singlets. Leptons, quarks and weak vector bosons are composites confined by SU(3)H local gauge interaction, where leptons are made of three constituent fermions and quarks are two-body composites of a scalar and a fermion. The number of the constituent particles is less in our model. There are less exotic leptons and quarks. Quark-lepton parallelism holds. Weak interactions appear only at the composite level as residual short-range interactions among hypercolor singlets. The violation of parity occurs by the mechanism of dynamical symmetry breaking. 相似文献
9.
M. Dineikhan S. A. Zhaugasheva K. Karimzhan 《Physics of Particles and Nuclei Letters》2009,6(5):386-396
Taking into account the relativistic and nonlocal character of interactions, the mass spectrum of mesons consisting of light-light
and light-heavy quarks with orbital and radial excitations is determined. Our results show that good agreement with the experimental
data for the slope and the intercept of the Regge trajectory can be obtained only by taking into account the nonperturbative
and the nonlocal character of interactions. There is certainly a dependence of the constituent mass of constituent particles
on the mass of a free state. When quarks are light, the difference in current and valent masses of quarks is greater than
in valent masses of quarks; when quarks are heavy, the difference in theses masses is insignificant. One alternative version
of the account of nonlocality is suggested for a definition of the properties of hadrons at large distances. The dependence
of constituent mass on the radius of confinement is studied. 相似文献
10.
We study a model in which particles interact with short-ranged attractive and long-ranged repulsive interactions, in an attempt to model the equilibrium cluster phase recently discovered in sterically stabilized colloidal systems in the presence of depletion interactions. At low packing fractions, particles form stable equilibrium clusters which act as building blocks of a cluster fluid. We study the possibility that cluster fluids generate a low-density disordered arrested phase, a gel, via a glass transition driven by the repulsive interaction. In this model the gel formation is formally described with the same physics of the glass formation. 相似文献
11.
We apply a modified mean-field density functional theory to determine the phase behavior of Stockmayer fluids in slit-like
pores formed by two walls with identical substrate potentials. Based on the Carnahan-Starling equation of state, a fundamental-measure
theory is employed to incorporate the effects of short-ranged hard-sphere-like correlations while the long-ranged contributions
to the fluid interaction potential are treated perturbatively. The liquid-vapor, ferromagnetic-liquid-vapor, and ferromagnetic-liquid-isotropic-liquid
first-order phase separations are investigated. The local orientational structure of the anisotropic and inhomogeneous ferromagnetic
liquid phase is also studied. We discuss how the phase diagrams are shifted and distorted upon varying the pore width. 相似文献
12.
Masakuni Ida 《Zeitschrift fur Physik C Particles and Fields》1985,28(4):529-536
Electroweak symmetry breaking is attributed to dynamical generation of quark masses. Our study is made in those models in which preons are confined by hypercolor gauge interactions to form massless quarks and leptons as well as heavy hyperhadrons or postons. The hierarchical nature of the breaking can be understood by assuming the necessity of infinite-range color interactions in addition to short-range postonic ones. Self-consistent mass equations forN families of quarks are given in an ideal limit in which left-right asymmetric effects and quark-lepton couplings are neglected. 相似文献
13.
A. Shabetai 《The European Physical Journal C - Particles and Fields》2007,49(1):169-175
Determining the degree of termalisation of the medium created in heavy ion collisions at RHIC remains highly debated. Elliptic
flow (v2) measurements at RHIC have already suggested the development of collectivity among partons before hadronization. If heavy
flavor hadrons flow with the light flavor hadrons, this indicates frequent interactions between the light (u, d ,s) and heavy
(c, b) quarks. Thus, thermalization of light quarks is likely to have been reached through partonic re-scattering. Experimentally
this can be probed by making a direct measurement of D-mesons v2 with sufficient precision at low transverse momentum. Using the Heavy Flavor Tracker (HFT) detector, the STAR experiment
at RHIC is proposing to both study this process and also to directly reconstruct charmed hadrons (D0, D+, Ds, ΛC, ...), using the displaced vertices of their decay products. The HFT is the first vertex detector to use a new and promising
CMOS active pixel sensor technology. It will allow to build a relatively fast, accurate and radiation tolerant detector, while
keeping the material budget low (∼0.3%X0 per layer). Detector design and physics performance simulations are presented. 相似文献
14.
We propose one a variant of calculation of the energy spectrum of bound state systems with relativistic corrections. In the
framework of quantum field theory, an expression that takes into account relativistic corrections to the mass of the bound
state with a known nonrelativistic pair interaction potential is proposed on the basis of calculating the asymptotic behavior
of correlation functions of the corresponding field currents with the necessary quantum numbers. Excluding the time variables
allows one to determine nonperturbative corrections to the interaction potential. The following results have been obtained
in the framework of this approach. The nonperturbative corrections arising due to the relativistic nature of a system to the
interaction Hamiltonian are determined. The dependence of the constituent mass of bound-state forming particles on the free
state mass and on the orbital and radial quantum numbers is analytically derived. The energy level shift of muonic hydrogen
taking into account relativistic corrections is calculated. The energy spectrum of a wide class of potentials that describe
the Coulomb bound state is analytically derived with relativistic corrections. The mass spectrum of the glueballs and the
constituent masses of the gluons are analytically calculated taking into account spin-orbit, spin—spin, and tensor interactions.
Our numerical results have shown very good agreement with the lattice data. Taking into account nonperturbative and nonlocality
characters of interactions, the mass spectrum of the mesons consisting of light-light and light-heavy quarks with orbital
and radial excitations is determined. Our results show that good agreement with the experimental data for the slope and the
intercept of the Regge trajectory can be obtained only taking into account the nonperturbative and the nonlocal characters
of interactions. The dependences of the constituent masses of constituent particles on the masses of a free state are certain.
When quarks are light, then the difference between current and valent masses of quarks is greater than valent masses of quarks,
and when quarks are heavy, then the difference between these masses is insignificant. One of the alternative variants of taking
nonlocality into account has been suggested for the definition of properties of hadrons at large distances. The dependence
of the constituent masses of constituent particles on the radius of confinement is determined. 相似文献
15.
S. Jonsell 《Few-Body Systems》2002,31(2-4):255-260
I study two interacting bosons confined to a harmonic trap. The interaction is assumed to be of zero range and is expressed
in terms of the s-wave scattering length. The energy shifts of the harmonic-oscillator states due to the atom-atom interaction are calculated
analytically. It is found that for an ordinary potential the interaction energy depends only on the scattering length, while
if the scattering length is modified by a near-threshold Feshbach resonance there is also a dependence on the width of the
resonance.
Received October 25, 2001; accepted for publication November 9, 2001 相似文献
16.
The medium-induced gluon radiation angular distributions of light quarks and heavy quarks outside a finite jet cone are studied.
We find the effect of destructive interference between the vacuum and medium-induced radiation plays an important role in
gluon radiation for very small value of path length L, which leads to the negative value of medium-induced energy loss. The medium-induced radiative energy loss outside an angle
for heavy quarks is found to have a minimum and a maximum at small angle for small path length, which are caused by dead cone
effect and Brownian k
⊥-broadening effect, respectively. However for large path length the minimum and maximum disappear. 相似文献
17.
An absorption-desorption model with long-ranged interaction is simulated by the dynamic Monte Carlo method.The dynamic process has an inert phase and an active phase that is controlled by the absorption rate.In the active phase,the number of vacancies increases with time exponentially,while in the inert phase the vacant sites will be occupied by adsorbates rapidly.At the critical absorption rate,both the number of vacancies and the time-depending active probability exhibit power-law behavior.We determine the critical absorption rate and the scaling exponents of the power-laws.The effect of the interaction range of desorption on the critical exponents is investigated.In the short-ranged interaction limit, the critical exponents of Schlogl's first model are recovered.The model may describe the sta bility of the inner Helmholtz layer,an essential component of the electrochemical double-layer capacitor at a nanowire. 相似文献
18.
It is demonstrated on the basis of the Dirac equation that quarks cannot be confined by a vector gluon potential of the form(r/r
0)a or[ln(r/r
0]a, a>0, if the quark-gluon interaction conserves parity. In order to confine quarks with the parity-conserving interaction, the effective gluon potential must be a pseudovector or a scalar. These are shown in a simple Yang-Mills field with theSU(2) group. 相似文献
19.
A model with competing short-ranged attractions and long-ranged repulsions that describes self-organized patterns in systems like Langmuir monolayers, magnetic films, and adsorbed monolayers is studied using numerical simulations and analytic theory. Simulations provide strong evidence confirming that the stripe phase order is destroyed in a defect unbinding transition. Large scale computer simulations are in agreement with an analytic scaling theory, which also predicts an eventual crossover from defect-mediated stripe melting to a spin-disordering (or particle-mixing) mechanism with decreasing repulsion strength. 相似文献
20.
We demonstrate that for a finite-size quark-gluon plasma the induced gluon radiation from heavy quarks is stronger than that
for light quarks when the gluon formation length becomes comparable with (or exceeds) the size of the plasma. The effect is
due to oscillations of the light-cone wave function for the in-medium q→gq transition. The dead cone model by Dokshitzer and Kharzeev neglecting quantum finite-size effects is not valid in this regime.
The finite-size effects also enhance the photon emission from heavy quarks. 相似文献