M. Drees

Parametrizations of the photon structure and applications to supersymmetric particle production at HERA

We presentQ2-dependent parametrizations for the parton distributions within real photons obtained from full solutions of the corresponding leading order evolution equations. We show that our results differ appreciably from fits of the “asymptotic” solutions. Furthermore we discuss the production of heavy quarks as well as squarks and gluinos at the HERA collider using our parametrizations. The production rates are very promising especially in the case of gluino production.

Intermediate-scale symmetry breaking and the spectrum of superpartners in superstring inspired supergravity models

Abstract It is demonstrated that intermediate scale symmetry breaking in superstring inspired supergravity models in general leads to non-negligible D -term contributions to scalar masses. Furthermore, the intermediate scale can change the evolution of the gauge couplings and might thus allow for rather light gluinos even if gaugino masses are the dominant sources of supersymmetry breaking in the visible sector.

Phenomenological consequences of N = 1 supergravity theories with non-minimal kinetic energy terms for vector superfields

Abstract It is shown that N=1 supergravity theories can have a GUT scale as large as the Planck scale if the kinetic energy terms for vector superfields are non-minimal. The canonical values for sin2θW (MW), α3 (MW) and m b m τ (M W ) are respected. In those theories masses of SU(3), SU(2) and U(1) gauginos may be different at the unification scale. Consequences for the low-energy particle spectrum are discussed in the extreme case where one of the gaugino masses is large while the other two vanish.

A new class of false vacua in low energy N = 1 supergravity theories

Abstract A new class of color and/or charge symmetry breaking vacua is shown to exist in models of particle physics based on N = 1 supergravity with a minimal low energy particle content. These unacceptable false vacua are eliminated by restricting the free parameter space of the theory to a greater extent than previously considered.

Upper mass bounds for the light neutral higgs boson in N=1 supergravity theories

Abstract A new evaluation of absolute upper mass bounds for the light neutral Higgs boson in N =1 supergravity theories with a minimal low energy particle content is presented for a top quark mass in the range 30 GeV ⩽ m t ⩽50 GeV . The bounds are found to significantly exceed previous estimated values. The effects due to some noncanonical versions of the model are shown to be rather unimportant. A finite gaugino mass, however, lowers the bounds significantly.

AssociateJ/ψ+γ production: a clean probe of gluon densities

AbstractWe discuss the associate production of aJ/ψ meson and a photon atn

Production rates for the light neutral Higgs boson in N = 1 supergravity theories

pbar p

Low energy properties of superstring-inspired SU(5) supergravity models

n (orpp) andep colliders. By requiring theJ/ψ to decay into ane+e− or μ+μ- pair, we end up with an exceptionally clean final state. Furthermore, in leading order it can only be produced via gluon fusion. This process can therefore serve as a very clean probe of the gluon densities inside the proton as well as the photon. Numerical results are presented for the tevatronn