15015533
QCD predictions for the transverse energy flow in deep-inelastic scattering in the DESY HERA small x regime.
The distribution of transverse energy [ital E][sub [ital T]], which accompanies deep-inelastic electron-proton scattering at small [ital x], is predicted in the central region away from the current jet and proton remnants. We use BFKL dynamics, which arises from the summation of multiple gluon emissions at small [ital x], to derive an analytic expression for the [ital E][sub [ital T]] flow. One interesting feature is an [ital x][sup [minus][epsilon]] increase of the [ital E][sub [ital T]] distribution with decreasing [ital x], where [epsilon]=(3[alpha][sub [ital s]]/[pi])2 ln2. We perform a numerical study to examine the possibility of using characteristics of the [ital E][sub [ital T]] distribution as a means of identifying BFKL dynamics at DESY HERA.
126229857
Structure Function Analysis and psi, Jet, W, Z Production: Pinning Down the Gluon
117807416
Diffractive deep inelastic scattering
A new approach to the analysis of diffractive deep inelastic data is presented. We show that the collinear factorisation theorem, which holds for diffractive DIS, has important modifications in the sub‐asymptotic HERA regime, which can be quantified by using perturbative QCD. In fact the diffractive parton densities are shown to satisfy an inhomogeneous evolution equation. Moreover it is necessary to include both the gluonic and sea‐quark t‐channel components of the perturbative Pomeron.
118665854
Diffraction and correlations at the LHC: definitions and observables
We note that the definition of diffractive events is a matter of convention. We discuss two possible “definitions”: one based on unitarity and the other on Large Rapidity Gaps (LRG) or Pomeron exchange. LRG can also arise from fluctuations and we quantify this effect and some of the related uncertainties. We find care must be taken in extracting the Pomeron contribution from LRG events. We show that long-range correlations in multiplicities can arise from the same multi-Pomeron diagrams that are responsible for LRG events, and we explain how early LHC data can illuminate our understanding of ‘soft’ interactions.
15108358
Off-diagonal parton distributions and their evolution
We construct off-diagonal parton distributions defined on the interval 0 ≤ X ≤ 1 starting from the off-forward distributions defined by Ji. We emphasize the particular role played by the symmetry relations in the “ERBL-like” region. We find the evolution equations for the off-diagonal distributions which conserve these symmetries. We present numerical results of the evolution, and verify that the analytic asymptotic forms of the parton distributions are reproduced. We also compare the constructed off-diagonal distributions with the non-forward distributions defined by Radyushkin and comment on the singularity structure of the basic amplitude written in terms of the off-diagonal distributions.
123328618
Proton-proton scattering and the pomeron
Abstract We describe various attempts to fit the data on pp and p p elastic scattering and total cross sections, including the recent ISR data, with a variety of Regge pole and cut models. Only two types of model are able to explain the data over the whole energy range satisfactorily. The simplest of these has no cuts, but a pomeron pole with trajectory α p(0) = 1.06 + 0.25 t , and a non-shrinking “core” term at large | t |. The other has a flat trajectory, α p( t ) = 1.06 for all t , and strong eikonal-model cuts which explain both the shrinkage at low | t |, and the lack of it at larger | t |. We also briefly review various speculations which relate the fact that α p(0) > 1 to the small triple-pomeron coupling.
17368592
Raising the unification scale in supersymmetry.
In the minimal supersymmetric standard model, the three gauge couplings appear to unify at a mass scale near 2{times}10{sup 16} GeV. We investigate the possibility that intermediate scale particle thresholds modify the running couplings so as to increase the unification scale. By requiring consistency of this scenario, we derive some constraints on the particle content and locations of the intermediate thresholds. There are remarkably few acceptable solutions with a single cleanly defined intermediate scale far below the unification scale.
5751474
Implications of supersymmetric models with natural R-parity conservation.
In the minimal supersymmetric standard model, the conservation of {ital R} parity is phenomenologically desirable, but is {ital ad} {ital hoc} in the sense that it is not required for the internal consistency of the theory. However, if {ital B}{minus}{ital L} is gauged at very high energies, {ital R} parity will be conserved automatically and exactly, provided only that all order parameters carry even integer values of 3({ital B}{minus}{ital L}). We propose a minimal extension of the supersymmetric standard model in which {ital R}-parity conservation arises naturally in this way. This approach predicts the existence of a very weakly coupled, neutral chiral supermultiplet of particles with electroweak-scale masses and lifetimes which may be cosmologically interesting. Neutrino masses arise via an intermediate-scale seesaw mechanism, and a solution to the {mu} problem is naturally incorporated. The apparent unification of gauge couplings at high energies is shown to be preserved in this approach. We also discuss a next-to-minimal extension, which predicts a pair of electroweak-scale chiral supermultiplets with electric charge 2. {copyright} {ital 1996 The American Physical Society.}
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.
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.
10342426
Physically meaningful and not so meaningful symmetries in Chern-Simons theory.
We explicitly show that the Landau gauge supersymmetry of Chern-Simons theory does not have any physical significance. In fact, the difference between an effective action that is both Becchi-Rouet-Stora (BRS) invariant and Landau supersymmetric and an effective action that is only BRS invariant is a finite field redefinition. Having established this, we use a BRS-invariant regulator that defines CS theory as the large mass limit of topologically massive Yang-Mills theory to discuss the shift [ital k][r arrow][ital k]+[ital c][sub [ital V]] of the bare Chern-Simons parameter [ital k] in connection with the Landau supersymmetry. Finally, to convince ourselves that the shift above is not an accident of our regularization method, we comment on the fact that all BRS-invariant regulators used as yet yield the same value for the shift.