Related papers: Quark and lepton masses at the GUT scale including…
We consider the production of SUSY scalar pairs at lepton colliders, for c.m. energies much larger than the mass of the heaviest SUSY (real or virtual) particle involved in the process. In that energy regime, we derive the leading and…
The structure of the quark and lepton masses and mixing angles provides one of the few windows we have on the underlying physics generating the \sm. In an attempt to identify the underlying symmetry group we look for the simplest gauge…
We probe the unification of down quarks and leptons in a supersymmetric SO(10) GUT. The large atmospheric neutrino mixing angle induces bR-sR transitions, which can account for the sizeable CP phase measured in Bs-Bsbar mixing. Corrections…
The top-quark Yukawa infrared fixed-point solution of the renormalization group equations, with minimal supersymmetry and GUT unification, defines a low-energy spectrum of supersymmetric particle masses in terms of a few GUT-scale…
We derive new constraints on the quantities delta_{XY}^{ij}, X,Y=L,R, which parametrise the flavour-off-diagonal terms of the charged slepton mass matrix in the MSSM. Considering mass and anomalous magnetic moment of the electron we obtain…
We discuss the fermion mass problem in SUSY GUTs, including such ideas as texture zeroes, and Georgi-Jarlskog textures. We focus on a specific supersymmetric model based on the gauge group $SU(4)\otimes SU(2)_L \otimes SU(2)_R$. In this…
We investigate the one-loop supersymmetric QCD (SUSY-QCD) and electroweak (SUSY-EW) corrections to the top quark decay into a b-quark and a longitudinal or transverse W-boson. The corrections are presented in terms of the longitudinal ratio…
We consider the high energy behaviour of the amplitudes for pair production of charged leptons, quarks, Higgs bosons, sleptons, squarks and charginos at lepton colliders. We give the general expressions of the leading quadratic and…
We present an updated fit of supersymmetric SO(10) models to quark and lepton masses and mixing parameters. Including latest results from lattice QCD determinations of quark masses and neutrino oscillation data, we show that fits neglecting…
We present selected results of our program to determine the masses, gauge couplings, and Yukawa couplings of the minimal supersymmetric model in a full one-loop calculation. We focus on the precise prediction of the strong coupling…
In F-theory GUTs, threshold corrections from Kaluza-Klein massive modes arising from gauge and matter multiplets play an important role in the determination of the weak mixing angle and the strong gauge coupling of the effective low energy…
In most versions of beyond the standard model (BSM) physics, the Yukawa couplings of the quarks and charged leptons are not all to the same complex scalar doublet but to different ones. Comparison to the standard model (SM) with only one…
Motivated by the possibility that new (gauge) symmetries which are broken at the grand- (string-) unification scale give rise to texture zeros in the fermion mass matrices which are at the origin of the hierarchy of masses and mixings we…
We investigate the possibility of adding a fourth generation of quarks. We also extend the Standard Model gauge group by adding another SU(N) component. In order to cancel the contributions of the fourth generation of quarks to the gauge…
We present the two-loop SUSY-QCD corrections to the effective bottom Yukawa couplings within the minimal supersymmetric extension of the Standard Model. The effective Yukawa couplings include the resummation of the non-decoupling…
We study $3$rd family Yukawa unification in the context of supersymmetric (SUSY) $\mathrm{SO}(10)$ GUTs and $\mathrm{SO}(10)$-motivated boundary conditions for the SUSY-breaking soft terms. We consider $\mu<0$ such that the SUSY…
We present a simple model for fermion mass matrices and quark mixing in the context of supersymmetric grand unified theories and show its agreement with experiment. Our model realizes the GUT mass relations $m_d=3m_e$, $m_s= m_\mu/3$,…
We show that matter yukawa couplings of the New Minimal Supersymmetric (SO(10)) GUT(NMSGUT) are subject to very significant GUT scale threshold corrections. Including these threshold effects relaxes the constraint $ y_b-y_\tau\simeq…
Supersymmetry predicts that gauge couplings are equal to the corresponding gaugino-sfermion-fermion Yukawa couplings. This prediction can be tested for the QCD sector of the MSSM by studying the processes eplus+eminus ->…
We study effects of SUSY particle decouplings on a quasi fixed point (QFP) of Yukawa coupling. From renormalization group analysis it is shown that if the SUSY breaking scale $M_S$ is large ($\simg 1$TeV), effects of decoupling of Higgsinos…