41996012
Stability of systems of three arbitrary charges: General properties.
The stability of systems consisting of a negative charge {minus}{ital q}{sub 1} and two positive charges {ital q}{sub 2} and {ital q}{sub 3} is discussed as a function of the values of the charges {ital q}{sub {ital i}} and of the constituent masses {ital m}{sub {ital i}}. We give general results and list some open questions of interest, which hopefully will stimulate further investigations.
120439787
A fit of upsilon and charmonium spectra
We show that upsilon and charmonium spectra can be fitted by a common potential of the form A + Br α , with α close to 0.1. In particular the mass difference of ϒ″′ and ϒ is reproduced within 10 MeV. In this way it is confirmed that for the
 b b ¯ and cĉ systems the relevant part of the potential is flavour-independent and approximately though not exactly logarithmic. At the same time the claims, according to which the short-distance part of the potential could be shown to agree with the predictions of QCD by a comparison of charmonium and upsilon spectra, are put in serious doubt.
122648419
Some comparison theorems on moments in the ground state and in excited states of a two-body system
Abstract We prove and extend some conjectures by Dib, Franzini and Gilman on the comparison of expectation values of r v in the ground state and the first radial excited state of a two-body system for a given, non-zero angular momentum. One of the by-products is that for usual potentials, the overall splitting of the P states is likely to be smaller for the excited state than for the ground state. We also make comparisons between the ground state and angular excitations and prove that the expectation values of r v , −3⩽ v l .
2463282
A Theorem on the real part of the high-energy scattering amplitude near the forward direction
Abstract We show that if for fixed negative (physical) square of the momentum transfer t , the differential cross-section dσ/dt tends to zero and if the total cross-section tends to infinity, when the energy goes to infinity, the real part of the even signature amplitude cannot have a constant sign near t = 0.
118027493
Some aspects of quarkonium spectroscopy
119346926
Improved constraints on states bound by a class of potentials
Recent work on states bound by a central potential whose Laplacian is positive is extended to cover a wider class of potentials for which energy level ordering theorems can be proved. This class includes power law potentials in particular. Constraints on the moments of the radial distance are improved and similarly for the kinetic energy. These constraints are shown to provide tight bounds on the energies of ground states for power law potentials, and on their variation with angular momentum. They are also used to bound the position of the maximum of the wavefunction for these states.
28053143
Renormalizable top-quark condensate models.
Recently it has been suggested that electroweak symmetry is broken by a top-quark vacuum condensate. We discuss the prospects for making a renormalizable version of this ``top bootstrap'' scenario using a strongly coupled spontaneously broken gauge interaction. Several specific models are considered. We argue that these models are somewhat similar to the extended technicolor models, but with a ``technicolor'' force which is broken, providing the mass-generation mechanism for the top quark. From this point of view, the top quark plays the role of a techniquark.
875394
phi4 model near the critical point: The Gaussian variational approximation.
Using the Gaussian variational approximation, we describe the approach to the continuum limit in φ 4 theory in 3+1 space-time dimensions. We study the solutions of the variational equations and their stability and compare our results with those of Monte Carlo calculations on a lattice. The importance of lattice effects is investigated by putting the Gaussian wave functional on a lattice. We find an abrupt decrease of the fourth derivative of the effective potential in the vicinity of the critical point, which is consistent with Monte Carlo calculations. In the continuum limit b→0 + , the renormalized theory shows a broken phase which is found to be asymptotically free, in agreement with the conclusions of Branchina et al
26174937
Description of F2 at small x incorporating angular ordering.
We study the perturbative QCD description of the DESY HERA measurements of {ital F}{sub 2}({ital x},{ital Q}{sup 2}) using a gluon distribution that is obtained from an evolution incorporating angular ordering of the gluon emissions, and which embodies both GLAP and BFKL dynamics. We compare the predictions with recent HERA data for {ital F}{sub 2} and its charm component {ital F}{sup {ital c}}{sub 2}. We also present estimates of the longitudinal structure function {ital F}{sub {ital L}}. {copyright} {ital 1996 The American Physical Society.}
10832623
Sparticle spectrum constraints.
The supersymmetric standard model with supergravity-inspired soft breaking terms predicts a rich spectrum of sparticles to be discovered at the SSC, LHC, and NLC. Because there are more supersymmetric particles than unknown parameters, one can write down sum rules relating their masses. We discuss the spectrum of sparticles from this point of view. Some of the sum rules do not depend on the input parameters and can be used to test the consistency of the model, while others are useful in determining the input parameters of the theory. If supersymmetry is discovered but the sum rules turn out to be violated, it will be evidence of new physics beyond the minimal supersymmetric standard model with universal soft supersymmetry-breaking terms.
36873731
Interference radiative phenomena in the production of heavy unstable particles.
We discuss the characteristic interference phenomena, including real as well as virtual radiative corrections, to the inclusive cross sections for production of heavy unstable systems such as {ital t{bar t}} or {ital W}{sup +}{ital W{minus}} pairs. We demonstrate explicitly the (fortunate) cancellation between emissions associated with the production of unstable particles and with their decays, and between emissions accompanying the decay stages. As a result the total interference effect is shown to be of {ital O}({alpha}{sub {ital i}}{Gamma}/{ital M}) or better (where {alpha}{sub {ital i}}={alpha} or {alpha}{sub {ital s}} as appropriate).