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1.
C. Albertus E. Hernández J. Nieves J. M. Verde-Velasco 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):183-199
We evaluate static properties and semileptonic decays for the ground state of doubly heavy Ξ, Ξ', Ξ
* and Ω, Ω', Ω
* baryons. Working in the framework of a nonrelativistic quark model, we solve the three-body problem by means of a variational
ansatz made possible by heavy-quark spin symmetry constraints. To check the dependence of our results on the inter-quark interaction
we use five different quark-quark potentials that include a confining term plus Coulomb and hyperfine terms coming from one-gluon
exchange. Our results for static properties (masses, charge radii and magnetic moments) are, with a few exceptions for the
magnetic moments, in good agreement with a previous Faddeev calculation. Our much simpler wave functions are used to evaluate
semileptonic decays of doubly heavy Ξ, Ξ'(J = 1/2) and Ω, Ω'(J = 1/2) baryons. Our results for the decay widths are in good agreement with calculations done within a relativistic quark
model in the quark-diquark approximation.
An erratum to this article is available at . 相似文献
2.
C. Albertus J. M. Flynn E. Hernández J. Nieves J. M. Verde-Velasco 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):725-727
The semileptonic decay B→π is studied starting from a simple quark model that takes into into account the effect of the B*-resonance. A novel, multiply subtracted, Omnès dispersion relation has been implemented to extend the predictions of the
quark model to all q2 values accessible in the physical decay. By comparison to the experimental data, we extract | V
ub| = (3.4±0.2(exp.)±0.7(theory))0-3. As a further test of the model, we have also studied D→π and D→K decays for which we get good agreement with experiment. 相似文献
3.
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
4.
M. Koll R. Ricken D. Merten B.C. Metsch H.R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):73-94
We present new results of a relativistic quark model based on the Bethe-Salpeter equation in its instantaneous approximation.
Assuming a linearly rising confinement potential with an appropriate spinorial structure in Dirac space and adopting a residual
interaction based on instanton effects, we can compute masses of the light mesons up to highest observed angular momenta with
a natural solution of the U
A(1) problem. The calculated ground states masses and the radial excitations describe the experimental results well. In this
paper, we will also discuss our results concerning numerous meson decay properties. For processes like π+/K
+↦e
+υeγ and 0-↦γγ at various photon virtualities, we find a good agreement with experimental data. We will also comment on the form factors
of the K
?3 decay and on the decay constants of the π, K and η mesons. For the sake of completeness, we will furthermore present the electromagnetic form factors of the charged π
and K mesons as well as a comparison of the radiative meson decay widths with the most recent experimental data.
Received: 28 August 2000 / Accepted: 12 September 2000 相似文献
5.
The semileptonic decay width of heavy baryons such as (Λ
b
→ Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field
operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The
present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally
measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution
inside the hadron as free parameters. 相似文献
6.
L. Theußl R.F. Wagenbrunn B. Desplanques W. Plessas 《The European Physical Journal A - Hadrons and Nuclei》2001,12(1):91-101
π and η decay modes of light baryon resonances are investigated within a chiral quark model whose hyperfine interaction is
based on Goldstone-boson exchange. For the decay mechanism a modified version of the 3
P
0 model is employed. Our primary aim is to provide a further test of the recently proposed Goldstone-boson exchange constituent
quark model. We compare the predictions for π and η decay widths with experiment and also with results from a traditional
one-gluon exchange constituent quark model. The differences between nonrelativistic and semirelativistic versions of the constituent
quark models are outlined. We also discuss the sensitivity of the results on the parameterization of the meson wave function
entering the 3
P
0 model.
Received: 11 May 2001 / Accepted: 17 September 2001 相似文献
7.
S. Ya. Kotkovskii 《JETP Letters》1997,65(10):768-772
The probability of inclusive semileptonic decay of B mesons is calculated in the constituent-quark model. A compact formula is obtained for the differential decay width of a
B meson in terms of the corresponding decay width of a free b quark and the wave function of the internal motion of the quarks in the B meson. Numerical values of semileptonic-decay widths are obtained for a series of models of the wave function.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 10, 734–737 (25 May 1997) 相似文献
8.
A.?Kadeer J.?G.?K?rner U.?Moosbrugger 《The European Physical Journal C - Particles and Fields》2009,59(1):27-47
Using the helicity method we derive complete formulas for the joint angular decay distributions occurring in semileptonic
hyperon decays including lepton-mass and polarization effects. Compared to the traditional covariant calculation, the helicity
method allows one to organize the calculation of the angular decay distributions in a very compact and efficient way. In the
helicity method the angular analysis is of cascade type, i.e. each decay in the decay chain is analyzed in the respective
rest system of that particle. Such an approach is ideally suited as input for a Monte Carlo event generation program. As a
specific example we take the decay
(l
−=e
−,μ
−) followed by the nonleptonic decay Σ
+→p+π
0 for which we show a few examples of decay distributions which are generated from a Monte Carlo program based on the formulas
presented in this paper. All the results of this paper are also applicable to the semileptonic and nonleptonic decays of ground-state
charm and bottom baryons, and to the decays of the top quark. 相似文献
9.
B. Metsch 《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):275-280
The scope of a relativistically covariant constituent quark model of baryons based on the Bethe-Salpeter equation in instantaneous
approximation is illustrated by a discussion of various baryon resonance observables such as static electromagnetic moments
--including a novel calculational procedure-- form factors and helicity amplitudes, semileptonic decays as well as the systematics
of two-body strong decay widths. 相似文献
10.
11.
The Geant4 CHIPS model simulates both decay and nuclear capture of negative muons. In hadron level models the muon is captured
by a proton, p(μ,νμ)n , and the neutron transfers to the nucleus only 5MeV, which is not enough to split a nucleon from the nucleus, while the
measured spectra of emitted nucleons reach 80MeV. In CHIPS, which considers asymptotically free quark-partons, the muon can
be captured by a quark, u(μ,νμ)d , and transfers 52MeV to the nucleus. This capture mechanism fits the main part of the nucleon spectra, while the high-energy
part of the spectra is not fitted. A precise fit of the high-energy part of the nucleon spectra can be made if the muon decay
μ → dˉνμ is taken into account. 相似文献
12.
V. Bednyakov E. Khramov N. Russakovich A. Tonoyan 《Physics of Particles and Nuclei Letters》2007,4(6):491-496
We have investigated the possibility of reconstructing the top quark charge through measurement of its decay product charges
at the ATLAS detector. Verification of the hypothesis about alternative interpretation of top-quark experimental data has
been considered as well. The method of “semileptonic B-meson decay” was applied for reconstructing the b-jet charge. A statistical significance of more than 5σ can be achieved using this method after analyzing 1 fb−1 of the t̄t-pairs data. The analysis was carried out with HERWIG and PYTHIA generators and using the GEANT4 detector simulation software
package.
The text was submitted by the authors in English. 相似文献
13.
By using a constituent quark model we compute the form factors relevant to semileptonic transitions of the B mesons into low-lying p-wave charmed mesons. We evaluate the q2 dependence of these form factors and compare them with other model calculations. The Isgur–Wise functions τ1/2 and τ3/2 are also obtained in the heavy quark limit of our results. PACS 13.25.Hw; 12.39.Hg; 12.39.Jh 相似文献
14.
E. Hernández J. Nieves J. M. Verde-Velasco 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):714-717
We evaluate semileptonic and two-meson nonleptonic decays of the B
c
- meson in the framework of a nonrelativistic quark model. The former are done in spectator approximation using one-body current
operators at the quark level. Our model reproduces the constraints of heavy-quark spin symmetry obtained in the limit of infinite
heavy-quark mass. For the two-meson nonleptonic decays we work in factorization approximation. We compare our results to the
ones obtained in different relativistic approaches. 相似文献
15.
We calculate the heavy-to-light form factors in a relativistic quark model with infrared heavy-quark propagators. Their -dependence in the physical region is defined by two parameters: the “infrared” parameter characterizing the infrared behaviour of the heavy quark and the mass difference of the heavy meson and the heavy quark . It is found that the values of the and form factors at are in excellent agreement with the available experimental data and other approaches whereas for transitions these values are found to be larger than those of several other models. The obtained form factors are used to
calculate the widths of the semileptonic decays of and mesons. A comparison of our results with available experimental data and other approaches is presented.
Received January 31, 1997; revised July 15, 1997; accepted for publication January 20, 1998 相似文献
16.
We investigate the semileptonic decays of heavy quarks in the leading non-trivial order in quantum chromodynamics. Effects of gluon corrections and the initial quark Fermi motion on the semileptonic rates and decay distributions are calculated. The resulting lepton energy spectrum for the charm semileptonic decay is compared with data to extract the mass of the charm quark. This is combined with the semileptonic branching ratio to predict the charm-quark lifetime. We find the lepton energy spectrum very stable with respect to gluon corrections. Expected spectra from the semileptonic decays of bottom and top quarks are presented. We also study the semileptonic decay process Q → q?v? + G, involving the emission of a single hard non-collinear gluon. This process should be observable with a branching ratio of a few percent in the decays of top (and heavier) quarks. 相似文献
17.
18.
19.
The decay widths for the radiative decays of heavy baryons are calculated in the heavy quark effective theory. Introducing
the interpolating fields for heavy baryons we obtain the transition matrix elements and the corresponding decay widths. Considering
theSU(6) flavor-spin wave functions for heavy baryons, the coupling constants are calculated in the nonrelativistic quark model.
Since the masses of the heavy baryons are not available, we have taken the predicted bag model masses. We find our results
are quite different from that of the heavy quark bag model calculations. 相似文献
20.
We present results for exclusive semileptonic decay widths of ground state spin-1/2 and spin-3/2 cb baryons corresponding to a c → s, d transition at the quark level. The relevance of hyperfine mixing in spin-1/2 cb baryons is shown. Our form factors are compatible with heavy quark spin symmetry constraints obtained in the infinite heavy quark mass limit. 相似文献