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.
120869890
Conformal field theory representation and background-independent action for superstring field theory
Abstract The two-dimensional conformal field theory representation of Witten's open superstring field theory is discussed. We argue that the previously suggested cubic action for the superstring is actually dependent on the spacetime background, and suggest a modification which formally removes this dependence. The transformation from the new version of the superstring cubic action to Witten's action for open string states is discussed. A class of linearized solutions to the equations of motion of the open superstring cubic action are exhibited. These solutions are in one-to-one correspondence with the physical excitations (both massless and massive) of the open and closed type I superstrings.
43631942
Refined gluino and squark pole masses beyond leading order
The physical pole and running masses of squarks and gluinos have recently been related at two-loop order in a mass-independent renormalization scheme. I propose a general method for improvement of such formulas, and argue that better accuracy results. The improved version gives an imaginary part of the pole mass that agrees exactly with the direct calculation of the physical width at next-to-leading order. I also find the leading three-loop contributions to the gluino pole mass in the case that squarks are heavier, using effective field theory and renormalization group methods. The efficacy of these improvements for the gluino and squarks is illustrated with numerical examples. Some necessary three-loop results for gauge coupling and fermion mass beta functions and pole masses in theories with more than one type of fermion representation, which are not directly accessible from the published literature, are presented in an Appendix.
122018065
BRST current algebra anomalies in string theory
Abstract We have calculated the operator product of the BRST current with itself in the cases of bosonic and fermionic strings. Despite some confusion in the recent literature, these operator products cannot vanish. In fact they are equal to total derivatives only if the total derivative part of the (super) BRST current is chosen correctly. Thus the BRST current algebra has anomalous Schwinger terms.
44961063
Two-loop scalar self-energies in a general renormalizable theory at leading order in gauge couplings
I present results for the two-loop self-energy functions for scalars in a general renormalizable field theory, using mass-independent renormalization schemes based on dimensional regularization and dimensional reduction. The results are given in terms of a minimal set of loop-integral basis functions, which are readily evaluated numerically by computers. This paper contains the contributions corresponding to the Feynman diagrams with zero or one vector propagator lines. These are the ones needed to obtain the pole masses of the neutral and charged Higgs scalar bosons in supersymmetry, neglecting only the purely electroweak parts at two-loop order. A subsequent paper will present the results for the remaining diagrams, which involve two or more vector lines. I also include an illustrative example, featuring several nontrivial consistency checks.
118973381
A Supersymmetry Primer
I provide a pedagogical introduction to supersymmetry. The level of discussion is aimed at readers who are familiar with the Standard Model and quantum field theory, but who have had little or no prior exposure to supersymmetry. Topics covered include: motivations for supersymmetry, the construction of supersymmetric Lagrangians, supersymmetry-breaking interactions, the Minimal Supersymmetric Standard Model (MSSM), R-parity and its consequences, the origins of supersymmetry breaking, the mass spectrum of the MSSM, decays of supersymmetric particles, experimental signals for supersymmetry, and some extensions of the minimal framework.
14833247
Deep inelastic events containing a forward photon as a probe of small x dynamics.
We calculate the rate of producing deep inelastic events containing an energetic isolated forward photon at DESY HERA. We quantify the enhancement arising from the leading log1/{ital x} gluon emissions with a view to using such events to identify the underlying dynamics. {copyright} {ital 1996 The American Physical Society.}
28650811
Crossing intrinsic depolarizing resonances by varying a partial Siberian snake.
We recently forced a 140 MeV polarized proton beam to cross intrinsic depolarizing resonances by varying a partial Siberian snake{close_quote}s strength for different values of the vertical and horizontal betatron tunes {nu}{sub {ital y}} and {nu}{sub {ital x}}. A weak second-order intrinsic resonance was observed in the {nu}{sub {ital x}} sweep; moreover, an unexpected partial spin flip was found in the {nu}{sub {ital y}} sweep. We also varied the snake ramp time to identify the {nu}{sub {ital y}} and {nu}{sub {ital x}} regions where the resonance crossings occurred during the snake variation; in these crossings the polarization partially deviated from Froissart-Stora behavior. {copyright} {ital 1996 The American Physical Society.}
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.
20265396
E3 transition probabilities in the platinum, mercury, and lead isotopes.
Spectroscopical properties of the platinum, mercury, and lead isotopes are studied within the Hartree-Fock plus BCS framework with the finite range density-dependent Gogny force. These properties are also studied beyond mean-field theory by combining the use of generator-coordinate-method-like wave functions with the angular momentum projection technique as to generate many-body correlated wave functions that are at the same time eigenstates of the angular momentum operator. We apply this formalism to the calculation of reduced transition probabilities {ital B}({ital E}3) from the lowest-lying octupole collective state to the ground state of several isotopes of the platinum, mercury, and lead nuclei whose experimental {ital B}({ital E}3) values present a peculiar behavior. The projected calculations show a large improvement over the unprojected ones when compared with the experimental data. The unprojected calculations are unable to predict any structure in the {ital B}({ital E}3). {copyright} {ital 1996 The American Physical Society.}
36563644
Gluon distribution at small x obtained from a unified evolution equation.
We solve a unified integral equation to obtain the x, ${\mathit{Q}}_{\mathit{T}}$, and Q dependence of the gluon distribution of a proton in the small x regime, where x and ${\mathit{Q}}_{\mathit{T}}$ are the longitudinal momentum fraction and the transverse momentum of the gluon probed at a scale Q. The equation generates a gluon with a steep ${\mathit{x}}^{\mathrm{\ensuremath{-}}\ensuremath{\lambda}}$ behavior, with \ensuremath{\lambda}\ensuremath{\sim}0.5, and a ${\mathit{Q}}_{\mathit{T}}$ distribution which broadens as x decreases. We compare our solutions with, on the one hand, those that we obtain using the double-leading-logarithm approximation to Altarelli-Parisi evolution and, on the other hand, to those that we determine from the BFKL equation.