Unitarization of Total Cross Section and Coherent Effect in pQCD

A formula to unitarize the leading-log BFKL-Pomeron amplitude is derived using a coherent property of two-body collision in the peripheral region. This procedure also allows an algebraic characterization of the Reggeon in QCD based on color, instead of the total angular momentum of the gluons being exchanged.Comment: Talk given at the DIS99 Meeting in Zeuthen, Germany. April, 1999. 3 page

A Higgs Test of Horizontal Symmetry

Identical interactions found in the three families of quarks and leptons suggest the presence of a horizontal symmetry. We discuss how such a symmetry can be tested by measuring the decay rates of Higgs into fermion pairs, and the Higgs production cross section. Depending on the details, there is a chance that the decay widths to the bottom-pair and the tau-pair may be down by more than a factor of 3 or more compared to the usual values, and the fusion production cross section of the Higgs also altered. Whatever the outcome, such a test also serves to constraint horizontal symmetry models.Comment: version to be published in Physics Letter

String Organization of Field Theories: Duality and Gauge Invariance

String theories should reduce to ordinary four-dimensional field theories at low energies. Yet the formulation of the two are so different that such a connection, if it exists, is not immediately obvious. With the Schwinger proper-time representation, and the spinor helicity technique, it has been shown that field theories can indeed be written in a string-like manner, thus resulting in simplifications in practical calculations, and providing novel insights into gauge and gravitational theories. This paper continues the study of string organization of field theories by focusing on the question of local duality. It is shown that a single expression for the sum of many diagrams can indeed be written for QED, thereby simulating the duality property in strings. The relation between a single diagram and the dual sum is somewhat analogous to the relation between a old- fashioned perturbation diagram and a Feynman diagram. Dual expressions are particularly significant for gauge theories because they are gauge invariant while expressions for single diagrams are not.Comment: 20 pages in Latex, including seven figures in postscrip

Perturbative Computation of Glueball Superpotentials

Using N=1 superspace techniques in four dimensions we show how to perturbatively compute the superpotential generated for the glueball superfield upon integrating out massive charged fields. The technique applies to arbitrary gauge groups and representations. Moreover we show that for U(N) gauge theories admitting a large N expansion the computation dramatically simplifies and we prove the validity of the recently proposed recipe for computation of this quantity in terms of planar diagrams of matrix integrals.Comment: 15 Pages, 2 Figure

On the Existence of the Quantum Action

We have previously proposed a conjecture stating that quantum mechanical transition amplitudes can be parametrized in terms of a quantum action. Here we give a proof of the conjecture and establish the existance of a local quantum action in the case of imaginary time in the Feynman-Kac limit (when temperature goes to zero). Moreover we discuss some symmetry properties of the quantum action.Comment: revised version, Text (LaTeX

Magic Neutrino Mass Matrix and the Bjorken-Harrison-Scott Parameterization

Observed neutrino mixing can be described by a tribimaximal MNS matrix. The resulting neutrino mass matrix in the basis of a diagonal charged lepton mass matrix is both 2-3 symmetric and magic. By a magic matrix, I mean one whose row sums and column sums are all identical. I study what happens if 2-3 symmetry is broken but the magic symmetry is kept intact. In that case, the mixing matrix is parameterized by a single complex parameter $U_{e3}$, in a form discussed recently by Bjorken, Harrison, and Scott.Comment: Two references added. To appear in Physics Letters

Testing J/psi Production and Decay Properties in Hadronic Collisions

The polar and azimuthal angular distributions for the lepton pair arising from the decay of a J/psi meson produced at transverse momentum p_T balanced by a photon [or gluon] in hadronic collisions are calculated in the color singlet model (CSM). It is shown that the general structure of the decay lepton distribution is controlled by four invariant structure functions, which are functions of the transverse momentum and the rapidity of the J/psi. We found that two of these structure functions [the longitudinal and transverse interference structure functions] are identical in the CSM. Analytical and numerical results are given in the Collins-Soper and in the Gottfried-Jackson frame. We present a Monte Carlo study of the effect of acceptance cuts applied to the leptons and the photon for J/psi+ gamma production at the Tevatron.Comment: 22 pages (LaTeX) plus 11 postscript figures, MAD/PH/822, YUMS94-11. Figures are available from the authors or as a compressed tar file via anonymous ftp at phenom.physics.wisc.edu in directory {}~pub/preprints/madph-94-822-figs.tar.

Unitarized Diffractive Scattering in QCD and Application to Virtual Photon Total Cross Sections

The problem of restoring Froissart bound to the BFKL-Pomeron is studied in an extended leading-log approximation of QCD. We consider parton-parton scattering amplitude and show that the sum of all Feynman-diagram contributions can be written in an eikonal form. In this form dynamics is determined by the phase shift, and subleading-logs of all orders needed to restore the Froissart bound are automatically provided. The main technical difficulty is to find a way to extract these subleading contributions without having to compute each Feynman diagram beyond the leading order. We solve that problem by using nonabelian cut diagrams introduced elsewhere. They can be considered as colour filters used to isolate the multi-Reggeon contributions that supply these subleading-log terms. Illustration of the formalism is given for amplitudes and phase shifts up to three loops. For diffractive scattering, only phase shifts governed by one and two Reggeon exchanges are needed. They can be computed from the leading-log-Reggeon and the BFKL-Pomeron amplitudes. In applications, we argue that the dependence of the energy-growth exponent on virtuality $Q^2$ for $\gamma^*P$ total cross section observed at HERA can be interpreted as the first sign of a slowdown of energy growth towards satisfying the Froissart bound. An attempt to understand these exponents with the present formalism is discussed.Comment: 41 pages in revtex preprint format, with 10 figure

J/Psi Decay Lepton Distribution in Hadronic Collisions

We propose the measurement of the decay angular distribution of leptons from J/Psi's produced at high transverse momentum balanced by a photon [or gluon] in hadronic collisions. The polar and azimuthal angular distribution are calculated in the color singlet model (CSM). It is shown that the general structure of the decay lepton distribution is controlled by four invariant structure functions, which are functions of the transverse momentum and the rapidity of the J/Psi. We found that two of these structure functions [the longitudinal and transverse interference structure functions] are identical in the CSM. We present analytical and numerical results in the Collins-Soper and in the Gottfried-Jackson frame.Comment: 8 pages, RevTex, 2 figures

The large-N(c) nuclear potential puzzle

An analysis of the baryon-baryon potential from the point of view of large-N(c) QCD is performed. A comparison is made between the N(c)-scaling behavior directly obtained from an analysis at the quark-gluon level to the N(c)-scaling of the potential for a generic hadronic field theory in which it arises via meson exchanges and for which the parameters of the theory are given by their canonical large-N(c) scaling behavior. The purpose of this comparison is to use large-N(c) consistency to test the widespread view that the interaction between nuclei arises from QCD through the exchange of mesons. Although at the one- and two-meson exchange level the scaling rules for the potential derived from the hadronic theory matches the quark-gluon level prediction, at the three- and higher-meson exchange level a generic hadronic theory yields a potential which scales with N(c) faster than that of the quark-gluon theory.Comment: 17 pages, LaTeX, 5 figure