arXiv subjects
Publications and source records attributed to T. Goldman.
Meson spectra can be well approximated by a specific form of a nonlinear Regge trajectory which is consistent with a finite number of bound states. This may have important consequencies for experiment, and may be a hint for the theory.
The mass estimate of the $d^* (IJ^P=03^+)$ dibaryon is improved by a dynamical calculation in the quark delocalization, color screening model. The partial decay width of $d^*$ into an $NN$ D-wave state is also obtained. The mass obtained is slightly larger than that obtained in adiabatic calculations, due to the anharmonicity of the effective potential between two $Δ$'s. The value of the width obtained due to tensor one-gluon-exchange is about 5 MeV, comparable in magnitude to earlier results found using pion exchange.
We study the questions of the existence and mass of the proposed $d' (IJ^P=00^-)$ dibaryon in the quark-delocalization, color-screening model (QDCSM). The transformation between physical and symmetry bases has been extended to the cases beyond the SU(2) orbital symmetry. Using parameters fixed by baryon properties and $NN$ scattering, we find a mild attraction in the $IJ^P=00^-$ channel, but it is not strong enough to form a deeply bound state as proposed for the $d'$ state. Nor does the (isospin) I=2 N$Δ$ configuration have a deeply bound state. These results show that if a narrow dibaryon $d'$ state does exist, it must have a more complicated structure.
The interference of charge-changing interactions, weaker than the V-A Standard Model (SM) interaction and having a different Lorentz structure, with that SM interaction, can, in principle, produce effects near the end point of the Tritium beta decay spectrum which are of a different character from those produced by the purely kinematic effect of neutrino mass expected in the simplest extension of the SM. We show that the existence of more than one mass eigenstate can lead to interference effects at the end point that are stronger than those occurring over the entire spectrum. We discuss these effects both for the special case of Dirac neutrinos and the more general case of Majorana neutrinos and show that, for the present precision of the experiments, one formula should suffice to express the interference effects in all cases. Implications for "sterile" neutrinos are noted.
We identify a plausible scenario based on quark-lepton symmetry which correlates long baseline oscillations with maximal mixing to sterile neutrinos. The implication for the Sudbury Neutrino Observatory (SNO) is that the neutral current signal will be found to suffer the same suppression from the Standard Solar Model prediction as obtains for the charged current signal. Flavor mixing among active neutrinos is expected to occur on shorter baselines with smaller mixing amplitudes.
We present theoretical arguments and strong phenomenological evidence that hadronic Regge trajectories are essentially nonlinear and can be well approximated, for phenomenological purposes, by a specific square-root form.
The work of Yuan et al. (Phys. Rev. C 60 (1999) 045203) is being represented as definitive regarding the non-existence of a particular nonstrange, isoscalar, spin three dibaryon which has been proposed. We comment on this paper and its relation to our work and that of others.
The charge symmetry breaking and charge independence breaking N-N ^1S_0 scattering length differences, Delta a_{CSB} and Delta a_{CIB}, are calculated by a resonating group method with a quark cluster model. By adding the QED-QCD interference effect to the quark mass difference and the electromagnetic interaction, the Delta a_{CSB} and Delta a_{CIB} values can be reproduced with model parameters constrained by the hadron isomultiplet mass splitting.
Using an unquenched lattice potential to calculate the spectrum of the bottomonium system, we demonstrate numerically that the effect of pair creation is to produce termination of hadronic Regge trajectories, in contrast to the Veneziano model and the vast majority of phenomenological generalizations. Termination of Regge trajectories may have significant experimental consequences.
We apply the quark delocalization and color screening model to nucleon-baryon scattering. A semi-quantitative fit to N-N, N-Lambda and N-Sigma phase shifts and scattering cross sections is obtained without invoking meson exchange. Quarks delocalize reasonably in all of the different flavor channels to induce effective nucleon-baryon interactions with both a repulsive core and with an intermediate range attraction in the cases expected.
Some consequences of the oscillations of neutral kaons and neutrinos are discussed, in particular, the possibility of oscillations of particles recoiling against kaons or neutrinos from the production process. We show that there are no stationary oscillations of these recoil particles in any order, and that the apparent long-wavelength oscillations, which might appear to result when an earlier treatment of ours was taken to higher order, are spurious. We show that the recoil particles may show a travelling interference pattern. It may be possible to observe this pattern for $Λ$s produced in a reaction, but there seems to be little hope of observing this for the case of neutrinos from muon decay.
The quark delocalization and color screening model is used for a systematic study of the effective potential between baryons in the u,d and s sector. The model is constrained by the properties of baryons and N-N scattering. The effective potentials for the N-N (IJ=01,10,11,00) channels and the N-Lambda and N-Sigma (IJ = (1/2)1, (1/2)0, (3/2)1, (3/2)0) channels fit the N-N, N-Lambda and N-Sigma scattering data reasonably well. This model predicts: There are rather strong effective attractions between decuplet-baryons; the effective attractions between octet-baryons are weak or even repulsive; and the attractions between decuplet- and octet-baryons lie in between.
We study the origins of the inaccuracies of Schwinger's nonet mass, and the Sakurai mass-mixing angle, formulae for the pseudoscalar meson nonet, and suggest new versions of them, modified by the inclusion of the pseudoscalar decay constants. We use these new formulae to determine the pseudoscalar decay constants and mixing angle. The results obtained, $f_8/f_π= 1.185\pm 0.040,$ $f_9/f_π=1.095\pm 0.020,$ $f_η/f_π= 1.085\pm 0.025,$ $f_{η^{'}}/f_π=1.195\pm 0.035,$ $θ= (-21.4\pm 1.0)^o,$ are in excellent agreement with experiment.
We show that Regge trajectories for all flavors suggested recently by Filipponi et al. cannot combine both meson spectroscopy and additivity of intercepts. Other defects of these trajectories are also discussed.
Scalar or right-chiral interaction currents may be expected to produce a neutrino coupled to the electron which is different from, and perhaps even orthogonal to, that coupled to the electron by the standard model weak interaction. We show that, using reasonable parameter values for such additional interactions, it is possible to generate a spectrum which, if analyzed in the manner commonly employed by experimental groups, produces a negative neutrino mass-squared.
A relativistic quark potential model is used to do a systematic search for quasi-stable dibaryon states in the $u$, $d$, and $s$ three flavor world. Flavor symmetry breaking and channel coupling effects are included and an adiabatic method and fractional parentage expansion technique are used in the calculations. The relativistic model predicts dibaryon candidates completely consistent with the nonrelativistic model.
We study the origins of the inaccuracies of Schwinger's nonet mass, and the Sakurai mass-mixing angle, formulae for the pseudoscalar meson nonet, and suggest new versions of them, modified by the inclusion of the pseudoscalar decay constants. We use these new formulae to determine the pseudoscalar decay constants and mixing angle. The results obtained, f_8/f_π=1.185\pm 0.040, f_9/f_π=1.095\pm 0.020, f_η/f_π=1.085\pm 0.025, f_{η^{'}}/f_π=1.195\pm 0.035, θ=(-21.4\pm 1.0)^o, are in excellent agreement with experiment.
Using the ``glueball dominance'' picture of the mixing between q\bar{q} mesons of different hidden flavors, we establish new glueball-meson mass relations which serve as a basis for glueball spectral systematics. For the tensor glueball mass 2.3\pm 0.1 GeV used as an input parameter, these relations predict the following glueball masses: M(0^{++})\simeq 1.65\pm 0.05 GeV, M(1^{--})\simeq 3.2\pm 0.2 GeV, M(2^{-+})\simeq 2.95\pm 0.15 GeV, M(3^{--})\simeq 2.8\pm 0.15 GeV. We briefly discuss the failure of such relations for the pseudoscalar sector. Our results are consistent with (quasi)-linear Regge trajectories for glueballs with slope \simeq 0.3\pm 0.1 GeV^{-2}.