Factorization in graviton interactions

The study of factorization in the linearized gravity is extended to the graviton scattering processes with a massive scalar particle, with a massless vector boson and also with a graviton. Every transition amplitude is shown to be completely factorized and the physical implications of their common factors are discussed.Comment: 5 pages, Revtex 3.0, SNUTP 93-7

A simple SO(10) GUT in five dimensions

A simple supersymmetric SO(10) GUT in five dimensions is considered. The fifth dimension is compactified on the $S^1/(Z_2\times Z_2^\prime)$ orbifold possessing two inequivalent fixed points. In our setup, all matter and Higgs multiplets reside on one brane (PS brane) where the original SO(10) gauge group is broken down to the Pati-Salam (PS) gauge group, SU(4)_c \timesSU(2)_L \times SU(2)$_R$, by the orbifold boundary condition, while only the SO(10) gauge multiplet resides in the bulk. The further breaking of the PS symmetry to the Standard Model gauge group is realized by Higgs multiplets on the PS brane as usual in four dimensional models. Proton decay is fully suppressed. In our simple setup, the gauge coupling unification is realized after incorporating threshold corrections of Kaluza-Klein modes. When supersymmetry is assumed to be broken on the other brane, supersymmetry breaking is transmitted to the PS brane through the gaugino mediation with the bulk gauge multiplet.Comment: 12 pages, 1 figure, some errors have been corrected (no change in conclusions

Ku-band system design study and TDRSS interface analysis

The capabilities of the Shuttle/TDRSS link simulation program (LinCsim) were expanded to account for radio frequency interference (RFI) effects on the Shuttle S-band links, the channel models were updated to reflect the RFI related hardware changes, the ESTL hardware modeling of the TDRS communication payload was reviewed and evaluated, in LinCsim the Shuttle/TDRSS signal acquisition was modeled, LinCsim was upgraded, and possible Shuttle on-orbit navigation techniques was evaluated

Determining Heavy Mass Parameters in Supersymmetric SO(10) Models

Extrapolations of soft scalar mass parameters in supersymmetric theories can be used to explore elements of the physics scenario near the grand unification scale. We investigate the potential of this method in the lepton sector of SO(10) which incorporates right-handed neutrino superfields. The method is exemplified in two models by exploring limits on the precision that can be expected from coherent LHC and e+e- collider analyses in the reconstruction of the fundamental scalar mass parameters at the unification scale and of the D-terms related to the breaking of grand unification symmetries. In addition, the mass of the third-generation right-handed neutrino can be estimated in seesaw scenarios. Even though the models are simplified and not intended to account for all aspects of a final comprehensive SO(10) theory, they provide nevertheless a valid base for identifying essential elements that can be inferred on the fundamental high-scale theory from high-energy experiments.Comment: 26 pp LaTeX; version published in Phys. Rev.

The neutralino projector formalism for complex SUSY parameters

We present a new formalism describing the neutralino physics in the context of the minimal supersymmetric model (MSSM), where CP violation induced by complex $M_1$ and $\mu$ parameters is allowed. The formalism is based on the construction of neutralino projectors, and can be directly generalized to non-minimal SUSY models involving any number of neutralinos. It extends a previous work applied to the real SUSY parameter case. In MSSM, the method allows to describe all physical observables related to a specific neutralino, in terms of its CP eigenphase and three complex numbers called its "reduced projector elements". As the experimental knowledge on the neutralino-chargino sectors will be being accumulated, the problem of extracting the various SUSY parameters will arise. Motivated by this, we consider various scenarios concerning the quantities that could be first measured. Analytical disentangled expressions determining the related SUSY parameters from them, are then derived, which also emphasize the efficiency of the formalism.Comment: Version accepted in Phys. Rev. D. e-mail: [email protected]

Coherent Population Trapping with Controlled Interparticle Interactions

We investigate Coherent Population Trapping in a strongly interacting ultracold Rydberg gas. Despite the strong van der Waals interactions and interparticle correlations, we observe the persistence of a resonance with subnatural linewidth at the single-particle resonance frequency as we tune the interaction strength. This narrow resonance cannot be understood within a meanfield description of the strong Rydberg--Rydberg interactions. Instead, a many-body density matrix approach, accounting for the dynamics of interparticle correlations, is shown to reproduce the observed spectral features

Nonlinear couplings and tree amplitudes in gauge theories

Following a remark advanced by Feynman,we study the connection between the form of the nonlinear vertices involving gauge particles and the Abelian gauge invariance of physical tree amplitudes. We show that this requirement, together with some natural assumptions, fixes uniquely the structure of the Yang-Mills theory. However, the constraints imposed by the above property are not sufficient to single out the gauge theory of gravitation.Comment: 12 pages. Requires macros RevTeX, prepictex, pictex, postpictex. TeX source is 69373 byte