Marek Olechowski

Electroweak symmetry breaking and bottom - top Yukawa unification

The condition of unification of gauge couplings in the minimal supersymmetric standard model provides successful predictions for the weak mixing angle as a function of the strong gauge coupling and the supersymmetric threshold scale. In addition, in some scenarios, e.g. in the minimal SO(10) model, the tau lepton and the bottom and top quark Yukawa couplings unify at the grand unification scale. The condition of Yukawa unification leads naturally to large values of tan�, implying a proper top quark–bottom quark mass hierarchy. In this work, we investigate the feasibility of unification of the Yukawa couplings, in the framework of the minimal supersymmetric standard model with (assumed) universal mass parameters at the unification scale and with radiative breaking of the electroweak symmetry. We show that strong correlations between the parameters µ0, M1/2 and � = B0 − (6r/7)A0 appear within this scheme, where r is the ratio of the top quark Yukawa coupling to its infrared fixed point value. These correlations have relevant implications for the sparticle spectrum, which presents several characteristic features. In addition, we show that due to large corrections to the running bottom quark mass induced through the supersymmetry breaking sector of the theory, the predicted top quark �

Soft supersymmetry breaking in KKLT flux compactification

Abstract We examine the structure of soft supersymmetry breaking terms in KKLT models of flux compactification with low energy supersymmetry. Moduli are stabilized by fluxes and nonperturbative dynamics while a de Sitter vacuum is obtained by adding supersymmetry breaking anti-branes. We discuss the characteristic pattern of mass scales in such a set-up as well as some features of 4D N = 1 supergravity breakdown by anti-branes. Anomaly mediation is found to always give an important contribution and one can easily arrange for flavor-independent soft terms. In its most attractive realization, the modulus mediation is comparable to the anomaly mediation, yielding a quite distinctive sparticle spectrum. In addition, the axion component of the modulus/dilaton superfield dynamically cancels the relative CP phase between the contributions of anomaly and modulus mediation, thereby avoiding dangerous SUSY CP violation.

Stability of flux compactifications and the pattern of supersymmetry breaking

We extend the KKLT approach to moduli stabilization by including the dilaton and the complex structure moduli into the effective supergravity theory. Decoupling of the dilaton is neither always possible nor necessary for the existence of stable minima with zero (or positive) cosmological constant. The pattern of supersymmetry breaking can be much richer than in the decoupling scenario of KKLT.

Radiative electroweak symmetry breaking and the infrared fixed point of the top quark mass

The infrared quasi fixed point solution for the top quark mass in the Minimal Supersymmetric Standard Model explains in a natural way large values of the top quark mass and appears as a prediction in many interesting theoretical schemes. Moreover, as has been recently pointed out, for moderate values of tan β, in order to achieve gauge and bottom-tau Yukawa coupling unification, the top quark mass must be within 10% of its fixed point value. In this work we show that the convergence of the top quark mass to its fixed point value has relevant consequences for the (assumed) universal soft supersymmetry breaking parameters at the grand unification scale. In particular, we show that the low-energy parameters do not depend on A0 and B0 but on the combination δ = B0 − A0/2. Hence, there is a reduction in the number of independent parameters. Most interesting, the radiative SU(2)L × U(1)Y breaking condition implies strong correlations between the supersymmetric mass parameter μ and the supersymmetry breaking parameters δ and M12 or m0. These correlations, which become stronger for tanβ<2, may have some fundamental origin, which would imply the need of a reformulation of the naive fine-tuning criteria. We analyse the implications of these correlations for the supersymmetric and Higgs particle spectrum of the theory.

Hierarchy of Quark Masses in the Isotopic Doublets in N=1 Supergravity Models

Abstract In the framework of some generic softly broken SUSY models we study the SU (2) × U(1) breaking by radiative corrections, starting with the Yukawa couplings which at the Planck scale M P satisfy h t = h b . Physically acceptable solutions exist with the heirarchy of VEVs: ν 2 / ν 1 ≈ m t / m b provided m t ⩾ 50 GeV. When the SUSY breaking is driven only by the gaugino mass the solutions uniquely predict ν 2 =O(10) ν 1 and the top mass in the range 50–65 GeV. Also, the mass ratio in the second quark generation can be accounted for.

New regions in the NMSSM with a 125 GeV Higgs

A bstractIt is pointed out that mixing effects in the CP-even scalar sector of the NMSSM can give 6-8 GeV correction to the SM-like Higgs mass in moderate or large tan β regions with a small value of the singlet-higgs-higgs superfields coupling λ ~

Haggling over the fine-tuning price of LEP

\mathcal{O}

Supersymmetry breakdown at a hidden wall

(0.1). This effect comes mainly from the mixing of the SM-like Higgs with lighter singlet. In the same parameter range, the mixing of the heavy doublet Higgs with the singlet may strongly modify the couplings of the singlet-like and the 125 GeV scalars. Firstly, the LEP bounds on a light singlet can be evaded for a large range of its masses. Secondly, the decay rates of both scalars can show a variety of interesting patterns, depending on the lightest scalar mass. In particular, a striking signature of this mechanism can be a light scalar with strongly suppressed (enhanced) branching ratios to

Bottom - up approach to unified supergravity models

b\overline{b}\left( {gg,c\overline{c},\gamma \gamma } \right)

Instabilities of bulk fields and anomalies on orbifolds

as compared to the SM Higgs with the same mass. The γγ decay channel is particularly promising for the search of such a scalar at the LHC. The 125 GeV scalar can, thus, be accommodated with substantially smaller than in the MSSM radiative corrections from the stop loops (and consequently, with lighter stops) also for moderate or large tan β, with the mixing effects replacing the standard NMSSM mechanism of increasing the tree level Higgs mass in the low tan β and large λ regime, and with clear experimental signatures of such a mechanism.