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.
15512478
Paramagnetic dominance, the sign of the beta function and UV/IR mixing in non-commutative U(1)
U(1) gauge theory on non-commutative Minkowski spacetime in the Feynman–'t Hooft background gauge is studied. In particular, UV divergences and non-commutative IR divergent contributions to the two, three and four-point functions are explicitly computed at one loop. We show that the negative sign of the beta function results from paramagnetism — producing UV charge anti-screening — prevailing over diamagnetism — giving rise to UV charge screening. This dominance in the field theory setting corresponds to tachyon magnification dominance in the string theory framework. Our calculations provide an explicit realization of UV/IR mixing and lead to an IR renormalization of the coupling constant, where now paramagnetic contributions produce screening and diamagnetic contributions anti-screening.
122604338
Nonlocalities in field theory
It has been known since the early 1980's that the computation of light-cone gauge Feynman integrals in the nμ∗ prescription yields both local and nonlocal ultraviolet divergences. Nevertheless, it was recently claimed that the nonlocal contributions to the Yang-Mills vacuum polarization tensor arise from application of the decomposition formula [q·n(q+p)·n]−1=(p·n)−1{−[(q+p)·n]−1+(q·n)−1}, p·n≠0. The purpose of this paper is to show that nonlocal ultraviolet divergences automatically appear in light-cone gauge Feynman integrals defined by the nμ∗ prescription, regardless whether the above decomposition formula is employed or not.
118725047
BRS techniques applied to the temporal-planar gauge with the vienna prescription: The dependence on the axial vectors
116367467
The Shift of the Chern-Simons parameter beyond one loop
120724746
DOES STOCHASTIC ANALYTIC REGULARIZATION PROVIDE QUANTUM FIELD THEORIES
We analyze whether the so-called method of stochastic analytic regularization is suitable as an intermediate step for constructing perturbative renormalized quantum field theories. We choose a λϕ3 in six dimensions to prove that this regularization method does not in general provide a quantum field theory. This result seems to apply to any field theory with a quadratically UV-divergent stochastic two-point function, for instance λϕ4 and gauge theories in four dimensions.
15021862
Low-energy supersymmetry with D-term contributions to scalar masses.
We investigate how the predictions of the Minimal Supersymmetric Standard Model are modified by D-term contributions to soft scalar masses, which arise whenever the rank of the gauge group at very high energies is greater than four. We give a parameterization of the most general such contributions that can occur when the unbroken gauge symmetry is an arbitrary subgroup of E_6, and show how the D-term contributions leave their imprint on physics at ordinary energies. We impose experimental constraints on the resulting parameter space and discuss some features of the resulting supersymmetric spectrum which differ from the predictions obtained with universal boundary conditions on scalar masses near the Planck scale. These include relations between squark and slepton masses; the behavior of $\sin^2 (\beta-\alpha)$ (which determines the production cross-section for the lightest Higgs scalar boson at an e+e- collider) and the mass of the pseudoscalar Higgs bosons; R_b [the ratio $\Gamma(Z -> b\overline b)/\Gamma(Z -> hadrons)$; and mass differences between charginos and neutralinos.
10588893
Parton distributions of the proton.
To obtain improved parton densities of the proton, we present a new global analysis of deep-inelastic and related data including, in particular, the recent measurements of [ital F][sub 2] at DESY HERA, of the asymmetry of the rapidity distributions of [ital W][sup [plus minus]] production at the Fermilab [ital p[bar p]] collider and of the asymmetry in Drell-Yan production in [ital pp] and [ital pn] collisions. We also incorporate data to determine the flavor dependence of the quark sea distributions. We find that the behavior of the partons at small [ital x] is consistent with the precocious onset of BFKL leading ln(1/[ital x]) dynamics. We discuss the ambiguities remaining in the gluon distribution. We present improved predictions for [ital W] boson (and [ital t] quark) production at the Fermilab [ital p[bar p]] collider.
29640694
Parton distributions at small x.
We perform a next-to-leading-order QCD analysis of the recent data for deep-inelastic lepton-nucleon scattering and related processes, in which we pay particular attention to the forms of the parton distributions at very small {ital x}. We discuss in detail, and we incorporate in the analysis, the theoretical QCD results leading to the singular {ital x}{sup {minus}1/2}-type behavior of the gluon and sea-quark distributions, as well as the modifications due to shadowing effects. We find the QCD shadowing corrections are significant for {ital x}{approx lt}10{sup {minus}3} even though the parton distributions are below their saturation limit. We give predictions for the structure functions {ital F}{sub 2} and {ital F}{sub {ital L}} accessible at the DESY {ital ep} collider HERA, and for {ital W} and {ital Z} production up to the energies of the CERN Large Hadron Collider and the Superconducting Super Collider. We discuss the possibility of experiments at these colliders probing the parton distributions in the very-small-{ital x} region.
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.}
16919657
Decoupling of the epsilon -scalar mass in softly broken supersymmetry.
It has been shown recently that the introduction of an unphysical [epsilon]-scalar mass [ital [tilde m]] is necessary for the proper renormalization of softly broken supersymmetric theories by dimensional reduction (DR). In these theories, both the two-loop [beta] functions of the scalar masses and their one-loop finite corrections depend on [ital [tilde m]][sup 2]. We find, however, that the dependence on [ital [tilde m]][sup 2] can be completely removed by slightly modifying the DR renormalization scheme. We also show that previous DR calculations of one-loop corrections in supersymmetry which ignored the [ital [tilde m]][sup 2] contribution correspond to using this modified scheme.