Sfermion decays into singlets and singlinos in the NMSSM

We investigate how the addition of the singlet Higgs field in the NMSSM changes the sfermion branching ratios as compared to the MSSM. We concentrate in particular on the third generation, discussing decays of the heavier stop, sbottom or stau into the lighter mass eigenstate plus a scalar or pseudoscalar singlet Higgs. We also analyse stop, sbottom and stau decays into singlinos. It turns out that the branching ratios of these decays can be large, markedly influencing the sfermion phenomenology in the NMSSM. Moreover, we consider decays of first and second generation sfermions into singlinos.Comment: 10 pages, 4 figures; a few additional remarks on the model, version to be publishe

Yukawa Induced Radiative Corrections to the Lightest Higgs Boson Mass in the NMSSM

We compute the leading logarithmic radiative corrections to the lightest Higgs mass in the NMSSM involving the electroweak gauge couplings and in the NMSSM specific Yukawa couplings lambda and kappa (including all mixed combinations), which are induced by chargino, neutralino and Higgs boson loops. The effect of the NMSSM specific Yukawa couplings lambda and kappa is to increase the upper bound on the lightest Higgs mass by up to ~2 GeV, but they can also decrease the lightest Higgs mass by up to ~-20 GeV.Comment: 12 pages, 3 figs, improved (generalized) treatment of CP odd loop contributions; the possibility to get large negative contributions to the lightest Higgs mass is clarified in a third figure; typos correcte

Cosmological evolution in compactified Horava-Witten theory induced by matter on the branes

The combined Einstein equations and scalar equation of motion in the Horava-Witten scenario of the strongly coupled heterotic string compactified on a Calabi-Yau manifold are solved in the presence of additional matter densities on the branes. We take into account the universal Calabi-Yau modulus phi with potentials in the 5-d bulk and on the 3-branes, and allow for an arbitrary coupling of the additional matter to phi and an arbitrary equation of state. No ad hoc stabilization of the five dimensional radius is assumed. The matter densities are assumed to be small compared to the potential for phi on the branes; in this approximation we find solutions in the bulk which are exact in y and t. Depending on the coupling of the matter to phi and its equation of state, various solutions for the metric on the branes and in the 5-d bulk are obtained: Solutions corresponding to a ``rolling radius'', and solutions with a static 5-d radius, which reproduce the standard cosmological evolution.Comment: 20 pages (LaTeX2e), no figs. References added and comments rectifie

The Cosmological Constant

Various contributions to the cosmological constant are discussed and confronted with its recent measurement. We briefly review different scenarious -- and their difficulties -- for a solution of the cosmological constant problem.Comment: Lecture given at the XIV Workshop "Beyond the Standard Model", Bad Honnef, 11-14 March 200

Testing the higgsino-singlino sector of the NMSSM with trileptons at the LHC

We propose a simplified light higgsino-singlino scenario in the NMSSM, in which the masses of the chargino and the lightest neutralino determine the masses and couplings of all 3 lightest neutralinos. This scenario is complementary to the simplified wino-like chargino/neutralino scenario used conventionally for the interpretation of results from trilepton searches, and motivated by lower bounds on the gluino mass in the case of GUT relations between the wino and gluino masses. We present all masses and mixing angles necessary for the determination of production cross sections of the chargino and the 3 neutralinos in the form of Tables in the M_{neutralino_1} - M_{chargino_1} plane, assuming Higgs mass motivated values for tan(beta)=2 and lambda=0.6. We show that this scenario leads to considerable signal rates, and present constraints in this plane from recent searches for trileptons at the LHC.Comment: 16 pages, 1 Figure, 8 Table

Gradient flows for β\beta functions via multi-scale renormalization group equations

Renormalization schemes and cutoff schemes allow for the introduction of various distinct renormalization scales for distinct couplings. We consider the coupled renormalization group flow of several marginal couplings which depend on just as many renormalization scales. The usual $\beta$ functions describing the flow with respect to a common global scale are assumed to be given. Within this framework one can always construct a metric and a potential in the space of couplings such that the $\beta$ functions can be expressed as gradients of the potential. Moreover the potential itself can be derived explicitly from a prepotential which, in turn, determines the metric. Some examples of renormalization group flows are considered, and the metric and the potential are compared to expressions obtained elsewhere.Comment: 8 page

S-Dual Gravity in the Axial Gauge

We investigate an action that includes simultaneously original and dual gravitational fields (in the first order formalism), where the dual fields are completely determined in terms of the original fields through axial gauge conditions and partial (non-covariant) duality constraints. We introduce two kinds of matter, one that couples to the original metric, and dual matter that couples to the dual metric. The linear response of both metrics to the corresponding stress energy tensors coincides with Einstein's equations. In the presence of nonvanishing standard and dual cosmological constants a stable solution with a time independent dual scale factor exists that could possibly solve the cosmological constant problem, provided our world is identified with the dual sector of the model.Comment: Parts of the Introduction rewritten; accepted for publication in CQ

Enhanced di-photon Higgs signal in the Next-to-Minimal Supersymmetric Standard Model

In the Next-to-Minimal Supersymmetric Standard Model, CP-even Higgs bosons can have masses in the range of 80-110 GeV in agreement with constraints from LEP due to their sizeable singlet component. Nevertheless their branching ratio into two photons can be 10 times larger than the one of a Standard Model Higgs boson of similar mass due to a reduced coupling to b quarks. This can lead to a spectacular enhancement of the Higgs signal rate in the di-photon channel at hadron colliders by a factor 6. Corresponding scenarios can occur in the Next-to-Minimal Supersymmetric Standard Model for a relatively low Susy breaking scale.Comment: 8 pages, 1 Figure, incorporation of recent LHC results and additional references. To be published in PL