1,250 research outputs found
Branching ratios of the decays of psi(3770) and Upsilon(10580) into light hadrons
Taking into account the new data on the full width of D^{\ast\pm}(2010) and
the mass difference of the charged and neutral beauty mesons B^\pm, B^0,\bar
B^0, the branching ratios of the decays psi(3770), Upsilon(10580) to pi^+pi^-,
K bar K, rho(omega)pi, rho(omega)eta, rho(omega)eta^prime, K^ast bar K+ c.c,
rho^+ rho^-, and K^ast bar K^ast are re-evaluated in the model in which the
Okubo-Zweig-Iizuka rule is violated due to the real intermediate state D\bar D
in case of psi(3770) and B\bar B in case of Upsilon(10580). The inclusive
annihilation of psi(3770) and Upsilon(10580) into light hadrons is discussed.Comment: 10 page
Conventional and manipulated growth of Cu-Cu(111)
Molecular beam epitaxy of Cu on Cu(111) was studied using thermal energy He scattering, in the temperature range between 100 and 450 K. Three-dimensional growth was observed in the whole temperature range. To determine the onset of various diffusion processes, submonolayer films formed by deposition at low temperature were annealed. Annealing proceeds in two steps. The first step is interpreted as a change in island shape, the second as Ostwald-ripening. A comparison with homoepitaxy on Pt(111) and Ag(111) is made. Growth manipulation was carried out by artificially increasing the island number density via intervention in the nucleation stage of each layer. The procedures applied were temperature reduction during nucleation as well as pulsed ion bombardment. These techniques enabled the convenient growth of good quality films consisting of a large number of monolayers. Finally, the use of oxygen as a surfactant modifying the growth mode was investigated. Under some growth conditions, pre-exposure of the surface to oxygen was found to induce weak He-intensity oscillations during deposition. The quality of the films grown in this way was, however, low
On the equivalence of pairing correlations and intrinsic vortical currents in rotating nuclei
The present paper establishes a link between pairing correlations in rotating
nuclei and collective vortical modes in the intrinsic frame. We show that the
latter can be embodied by a simple S-type coupling a la Chandrasekhar between
rotational and intrinsic vortical collective modes. This results from a
comparison between the solutions of microscopic calculations within the HFB and
the HF Routhian formalisms. The HF Routhian solutions are constrained to have
the same Kelvin circulation expectation value as the HFB ones. It is shown in
several mass regions, pairing regimes, and for various spin values that this
procedure yields moments of inertia, angular velocities, and current
distributions which are very similar within both formalisms. We finally present
perspectives for further studies.Comment: 8 pages, 4 figures, submitted to Phys. Rev.
A method for determining CP violating phase
A new way of determining the phases of weak amplitudes in charged decays
based on SU(3) symmetry is proposed. The CP violating phase can now be
determined without the previous difficulty associated with electroweak
penguins.Comment: 9 pages plus one figure, Revte
Isoscalar-isovector mass splittings in excited mesons
Mass splittings between the isovector and isoscalar members of meson nonets
arise in part from hadronic loop diagrams which violate the Okubo-Zweig-Iizuka
rule.
Using a model for these loop processes which works qualitatively well in the
established nonets, I tabulate predictions for the splittings and associated
isoscalar mixing angles in the remaining nonets below about 2.5 GeV, and
explain some of their systematic features.
The results for excited vector mesons compare favorably with experiment.Comment: 8 RevTeX pages, including 1 LaTeX figure.
CMU-HEP93-23/DOE-ER-40682-4
Nonresonant Semileptonic Heavy Quark Decay
In both the large N_c limit and the valence quark model, semileptonic decays
are dominated by resonant final states. Using Bjorken's sum rule in an
"unquenched" version of the quark model, I demonstrate that in the heavy quark
limit nonresonant final states should also be produced at a significant rate.
By calculating the individual strengths of a large number of exclusive two-body
nonresonant channels, I show that the total rate for such processes is highly
fragmented. I also describe some very substantial duality-violating suppression
factors which reduce the inclusive nonresonant rate to a few percent of the
total semileptonic rate for the finite quark masses of B decay, and comment on
the importance of nonresonant decays as testing grounds for very basic ideas on
the structure, strength, and significance of the quark-antiquark sea and on
quark-hadron duality in QCD.Comment: 51 pages, 2 Postscript figure
On the existence of exotic and non-exotic multiquark meson states
To obtain an exact solution of a four-body system containing two quarks and
two antiquarks interacting through two-body terms is a cumbersome task that has
been tackled with more or less success during the last decades. We present an
exact method for the study of four-quark systems based on the hyperspherical
harmonics formalism that allows us to solve it without resorting to further
approximations, like for instance the existence of diquark components. We apply
it to systems containing two heavy and two light quarks using different
quark-quark potentials. While states may be stable in nature,
the stability of states would imply the existence of quark
correlations not taken into account by simple quark dynamical models.Comment: 3 pages. Contribution to the 20th European Conference on Few-Body
Problems in Physics, Pisa, Italy. To be published in Few-Body system
SU(3) Symmetry Breaking and Octet Baryon Polarizabilities
Static polarizabilities of the low--lying baryons are studied within
the collective coordinate approach to the three flavor generalization of the
Skyrme model; in particular, magnetic polarizabilities are considered.
Predicted polarizabilities, which result from different treatments of the
strange degrees of freedom in this model, are critically compared. Their
deviations from the flavor symmetric formulations are discussed.Comment: 11 pages, LaTeX, 4 tables, no figures, final version to be published
in Phys. Lett.
Manipulation of growth modes in heteroepitaxy: Ni-Cu(111)
Growth manipulation methods, which have been successfully used to improve the growth of homoepitaxialfilms, are applied to molecular beam epitaxy of the heteroepitaxial system Ni/Cu(111). The procedures applied are temperature reduction during nucleation and pulsed ion bombardment during deposition. While the first does not lead to smoother films, the ion beam assisted growth is successful in reducing the film roughness
Strong and Electromagnetic Decays of the Baryon Decuplet
We discuss the strong and radiative decays of the decuplet of baryon
resonances to the baryon octet in chiral perturbation theory. We comment on the
implications for the polarisability of the nucleon.Comment: 16 pages + 5 figures (.ps files) appended to file. Uses tables.tex
and harvmac.te
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