共查询到20条相似文献,搜索用时 15 毫秒
1.
C. Albertus E. Hernández J. Nieves J. M. Verde-Velasco 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):691-694
Working in the framework of a nonrelativistic quark model we evaluate the spectra and semileptonic decay widths for the ground
state of doubly heavy Ξ and Ω baryons. We solve the three-body problem using a variational ansatz made possible by the constraints imposed by heavy-quark
spin symmetry. In order to check the dependence of our results on the inter-quark interaction, we have used five different
quark-quark potentials which include Coulomb and hyperfine terms coming from one-gluon exchange, plus a confining term. Our
results for the spectra are in good agreement with a previous calculation done using a Faddeev approach. For the semileptonic
decay our results for the total decay widths are in good agreement with the ones obtained within a relativistic quark model
in the quark-diquark approximation. 相似文献
2.
S. Migura D. Merten B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2006,28(1):55-62
We calculate semileptonic decays of light and heavy baryons in a relativistically covariant constituent quark model. The model
is based on the Bethe-Salpeter equation in instantaneous approximation. It generates satisfactory mass spectra for mesons
and baryons up to the highest observable energies. Without introducing additional free parameters we compute on this basis
helicity amplitudes of electronic and muonic semileptonic decays of baryons. We thus obtain form factor ratios and decay rates
in good agreement with experiment. 相似文献
3.
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
4.
The recent observation at the Tevatron of (uub and ddb) baryons within 2 MeV of the predicted Σb-Λb splitting and of baryons at the Tevatron within a few mega electron volts (MeV) of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of = 5790-5800 MeV is reviewed and similar methods used to predict the masses of the excited states and . The main source of uncertainty is the method used to estimate the mass difference mb-mc from known hadrons. We verify that corrections due to the details of the interquark potential and to Ξb- mixing are small. For S-wave qqb states we predict , and . For states with one unit of orbital angular momentum between the b quark and the two light quarks we predict , and . Results are compared with those of other recent approaches. 相似文献
5.
S. Migura D. Merten B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2006,28(1):41-53
We calculate mass spectra of charmed baryons within a relativistically covariant quark model based on the Bethe-Salpeter equation
in instantaneous approximation. Interactions are given by a linearly rising three-body confinement potential and a flavor-dependent
two-body force derived from QCD instanton effects. This model has already been successfully applied to the calculation of
light flavor baryon spectra and is now extended to heavy baryons. Within the same framework we compare the results to those
obtained with the more conventional one-gluon exchange potential. 相似文献
6.
7.
W. Schott G. Dollinger T. Faestermann J. Friedrich F. J. Hartmann R. Hertenberger N. Kaiser A. R. Müller S. Paul A. Ulrich 《The European Physical Journal A - Hadrons and Nuclei》2006,30(3):603-611
The hyperfine-state population of hydrogen after the bound-β-decay of the neutron directly yields the neutrino left-handedness
or a possible right-handed admixture and possible small scalar and tensor contributions to the weak force. Using the through-going
beam tube of a high-flux reactor, a background free hydrogen rate of ca. 3s^-1 can be obtained. The detection of the neutral
hydrogen atoms and the analysis of the hyperfine states is accomplished by Lamb shift source type quenching and subsequent
ionization. The constraints on the neutrino helicity and the scalar and tensor coupling constants of the weak interaction
can be improved by a factor of ten. 相似文献
8.
The static properties and semileptonic decays of ground-state doubly heavy baryons are studied in the framework of a non-relativistic quark model. Using a phenomenological potential model, we calculate the ground-state masses and magnetic moments of doubly heavy Ω and Ξ baryons. In the heavy quark limit, we introduce a simple form of the universal Isgur-Wise function used as the transition form factor and then investigate the exclusive \begin{document}$ b \rightarrow c $\end{document} ![]()
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semileptonic decay widths and branching fractions for \begin{document}$ \dfrac{1}{2}\rightarrow \dfrac{1}{2} $\end{document} ![]()
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baryon transitions. Our obtained results are in agreement with other theoretical predictions. 相似文献
9.
Y.B. DongOn leave from Institute of High Energy Physics Academia Sinica Beijing P. R. China--> A. Faessler K. Shimizu 《The European Physical Journal A - Hadrons and Nuclei》1999,6(2):203-210
Electromagnetic form factors of protons and neutrons are investigated based on a relativistic quark model with the inclusion
of a pion cloud. Pseudo-scalar π-quark interaction is employed to study the coupling between the nucleon and the π. The results
show the important role of the pion cloud for the neutron charge form factor. Moreover, our numerical analysis indicates a
difference between the relativistic and the nonrelativistic treatments.
Received: 10 March 1999 / Revised version: 14 June 1999 相似文献
10.
A. C. dos Reis 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):474-478
The issue of Kπ and ππ
S-wave amplitude is addressed using decays of D-mesons. Model-independent measurements of the phases of the π
+
π
+ and K
-
π
+
S-wave amplitude from D
+→π
-
π
+
π
+ and D
+→K
-
π
+
π
+ decays are discussed. The result indicates a deviation from the phase of the K
-
π
+
S-wave amplitude obtained by scattering experiments. This could be interpreted as an indication of the presence of 3-body final-state
interaction, or in other words, that the phases from production and scattering process cannot be directly compared. 相似文献
11.
T. Matsuki T. Morii K. Sudoh 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):701-704
The recent discovery of Ds states suggests the existence of radial excitations. Our semirelativistic quark potential model succeeds in reproducing these
states within one to two percent of accuracy compared with the experiments, D
s0(2860) and D
s
*(2715), which are identified as 0+ and 1- radial excitations (n = 2). We also present calculations of radial excitations for B/B
s heavy mesons. The relation between our formulation and the modified Goldberger-Treiman relation is also described. 相似文献
12.
L. A. M. Salcedo J. P. B. C. de Melo D. Hadjimichef T. Frederico 《The European Physical Journal A - Hadrons and Nuclei》2006,27(2):213-223
We study the scaling of the 3S1-1S0 meson mass splitting and the pseudoscalar weak-decay constants with the mass of the meson, as seen in the available experimental
data. We use an effective light-front QCD-inspired dynamical model regulated at short distances to describe the valence component
of the pseudoscalar mesons. The experimentally known values of the mass splitting, decay constants (from global lattice-QCD
averages) and the pion charge form factor up to 4 [GeV/c]2 are reasonably described by the model. 相似文献
13.
The masses of the SU(3)×SU(6) hadrons are calculated in the chiral-invariant phase space (CHIPS) model as a sum of the mean energies of the quarks at
a constant temperature T
c with the color-magnetic splitting and the color-electric shift. The masses of hadrons are parametrized by four constants:
T
c, ms, E
CE and A
CM. With the same number of parameters the CHIPS model fits the masses of hadrons better than the classic bag model. The small
mass of the d-quark ( m
d = 2.7MeV) is used to prove that the isotopic shifts of hadrons can be explained by the mass difference between the d- and u-quarks. The dibaryon mass is estimated in CHIPS to be 200MeV higher than in the bag model. The prediction for the mass of the α* cluster is about the same in both models. It is close to 4 .
m
Δ.
Received: 12 December 2001 / Accepted: 23 May 2002 相似文献
14.
U. Löring B.Ch. Metsch H.R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2001,10(4):395-446
This is the second of a series of three papers treating light-baryon resonances up to 3 GeV within a relativistically covariant
quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In this paper
we apply the covariant Salpeter framework (which we developed in the first paper, U. L?ring, K. Kretzschmar, B.Ch. Metsch,
H.R. Petry, Eur. Phys. J. A 10, 309 (2001)) to specific quark model calculations. Quark confinement is realized by a linearly rising three-body string potential
with appropriate spinorial structures in Dirac space. To describe the hyperfine structure of the baryon spectrum we adopt
't Hooft's residual interaction based on QCD-instanton effects and demonstrate that the alternative one-gluon exchange is
disfavored on phenomenological grounds. Our fully relativistic framework allows to investigate the effects of the full Dirac
structures of residual and confinement forces on the structure of the mass spectrum. In the present paper we present a detailed
analysis of the complete non-strange-baryon spectrum and show that several prominent features of the nucleon spectrum such
as, e.g., the Roper resonance and approximate “parity doublets” can be uniformly explained due to a specific interplay of relativistic
effects, the confinement potential and 't Hooft's force. The results for the spectrum of strange baryons will be discussed
in a subsequent paper, see U. L?ring, B.Ch. Metsch, H.R. Petry, this issue, p. 447.
Received: 27 March 2001 / Accepted: 17 April 2001 相似文献
15.
Mass spectra of the ground-state baryons consisting of three or two heavy (b or c ) and one light (u,d,s) quarks are calculated in the framework of the relativistic quark model and the hyperspherical expansion. The predictions of masses of the triply and doubly heavy baryons are obtained by employing the perturbation theory for the spin-independent and spin-dependent parts of the three-quark Hamiltonian. 相似文献
16.
T. Van Cauteren J. Ryckebusch B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):613-615
We present some of our results for the electromagnetic properties of excited Σ hyperons, computed within the framework of the Bonn constituent-quark model, which is based on the Bethe-Salpeter approach.
The seven parameters entering the model are fitted against the best-known baryon masses. Accordingly, the results for the
form factors and helicity amplitudes are genuine predictions. We compare with the scarce experimental data available and discuss
the processes in which Σ
*'s may play an important role. 相似文献
17.
18.
Weak electric and magnetic form factors for semileptonic baryon decays in a relativistic quark model
Weak electric and magnetic form factors for semileptonic baryon decays are calculated in a relativistic quark model based
on the Dirac equation with the independent-quark confining potential of the formV
q(r)=1/2(1+γ
0)(a
2
r+V
0). The values obtained for (g
2/g
1) are not very much different from the nonrelativistic results of Donoghue and Holstein. The values of (g
1/f
1) extracted from our model calculations of (f
2/f
1) in the Cabibbo limit compare well with the experimental values. The values of (f
2/f
1) for various semileptonic transitions are also estimated incorporating phenomenologically the effect of nonzerog
2 in the ratio (g
1/f
1). It is found that the SU(3)-symmetry breaking does not generate significant departures in (f
2/f
1) values from the corresponding Cabibbo predictions. 相似文献
19.
20.
A relativistic quark model based on Dirac equation with the independent-quark confining potential of the form (1 +γ
0)[a ln(r/b)] is used to compute the weak electric and magnetic form factors for semileptonic baryonic decays in the electronic decay
modes. The values obtained for (g
2/g
1) agree with the non relativistic results and those for (f
2/f
1) agree with the MIT bag model values of Donoghue and Holstein. The SU(3) symmetry breaking does not generate appreciable
departures in (f
2/f
1) values from corresponding Cabibbo values. 相似文献