471847
Search for supersymmetry with a light gravitino at the Fermilab Tevatron and CERN LEP colliders.
We analyze the prospects for discovering supersymmetry at the Fermilab Tevatron and CERN LEP colliders in the scenario that the lightest supersymmetric particle is a gravitino of mass {approx_lt}1 keV. We consider in particular the case that the lightest neutralino has a nearly 100{percent} branching fraction into gravitino+photon within the detector. This implies that supersymmetric events should contain both missing (transverse) energy and two energetic photons. Therefore, one can search for supersymmetry simply through inclusive production of superpartners. We consider the exclusion and reach capabilities of the Tevatron in exploring the supersymmetric parameter space, and study the efficiencies which can be achieved in this search. We also consider the discovery reach and backgrounds at LEP with {radical}{ital s}=160, 175, and 190 GeV. {copyright} {ital 1996 The American Physical Society.}
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.
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.
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.
18738644
Observable jets from the BFKL chain.
We derive a modified form of the BFKL equation which enables the structure of the gluon emissions to be studied in small {ital x} deep-inelastic scattering. The equation incorporates the resummation of the virtual and unresolved real gluon emissions. We solve the equation to calculate the number of small {ital x} deep-inelastic events containing 0,1,2,... resolved gluon jets, that is, jets with transverse momenta {ital q}{sub {ital T}}{gt}{mu}. We study the jet decomposition for different choices of the jet resolution parameter {mu}. {copyright} {ital 1996 The American Physical Society.}
32650827
tau polarization as a signal of charged Higgs bosons.
A measurement of the {tau} polarization at hadron colliders offers an excellent signal for the detection of charged Higgs bosons, via the decay {ital H}{sup {plus minus}}{r arrow}{tau}{sup {plus minus}}{nu}. We show how such a determination can distinguish these events from the {ital W}{sup {plus minus}}{r arrow}{tau}{sup {plus minus}}{nu} background, for each of the {tau}{r arrow}{pi}{nu}, {rho}{nu}, {ital a}{sub 1}{nu}, and {ital l}{nu}{bar {nu}} decay channels.
16871479
Hamiltonian quantization of general relativity with the change of signature.
We show in this article how the usual hamiltonian formalism of General Relativity should be modified in order to allow the inclusion of the Euclidean classical solutions of Einstein's equations. We study the effect that the dynamical change of signature has on the superspace and we prove that it induces a passage of the signature of the supermetric from ($-+++++$) to ($+-----$). Next, all these features are more particularly studied on the example of minisuperspaces. Finally, we consider the problem of quantization of the Euclidean solutions. The consequences of different choices of boundary conditions are examined.
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.}
35063065
Deep-inelastic events containing a measured jet as a probe of QCD behavior at small x.
We examine the proposal that deep-inelastic ({ital x},{ital Q}{sup 2}) scattering events which contain an identified jet, with transverse momentum squared {ital k}{sup 2}{congruent}{ital Q}{sup 2}, allow an ideal determination of the QCD behavior at very small {ital x}. We solve the Lipatov equation to predict the shape of the jet spectrum in such events and show that measurements at the DESY {ital ep} collider HERA should be able to verify, inter alia, whether the gluon indeed has the theoretically anticipated {ital g}{similar to}{ital x}{sup {minus}{alpha}}{sub {ital P}} small-{ital x} behavior with the intercept {alpha}{sub {ital P}} of the bare perturbative QCD Pomeron possible as large as 1.5.