Renormalization Group Improved Radiative Corrections to the Supersymmetric Higgs Boson Masses

The one-loop radiative corrections to the Higgs boson potential in the MSSM, originating from the top quark and squark loops, are summed in the leading log approximation using the renormalization group. The RG improved effective potential is minimized and the corrections to the CP-odd and CP-even Higgs boson masses are calculated. The resulting masses exhibit smoother top mass dependence than those calculated without RG summation. We have also found that for preferable values of the top mass the light Higgs mass does not exceed 100 GeV.Comment: 10 PAGES, 1 FIGURE ENCLOSED, LATE

IS (Low Energy) SUSY STILL ALIVE?

Supersymmetry, a new symmetry that relates bosons and fermions in particle physics, still escapes observation. Search for supersymmetry is one of the main aims of the Large Hadron Collider. The other possible manifestation of supersymmetry is the Dark Matter in the Universe. The present lectures contain a brief introduction to supersymmetry in particle physics. The main notions of supersymmetry are introduced. The supersymmetric extension of the Standard Model -- the Minimal Supersymmetric Standard Model -- is considered in more detail. Phenomenological features of the Minimal Supersymmetric Standard Model as well as possible experimental signatures of supersymmetry at the Large Hadron Collider are described. The present limits on supersymmetric particles are presented and the allowed region of parameter space of the MSSM is shown.Comment: 59 pages, 35 figures, PDFLatex, Lectures at the European School of High-Energy Physics, June 2012, Anjou, Franc

On free energy of 2-d black hole in bosonic string theory

Trying to interpret recent matrix model results (hep-th/0101011) we discuss computation of classical free energy of exact dilatonic 2-d black hole from the effective action of string theory. The euclidean space-time action evaluated on the black hole background is divergent due to linear dilaton vacuum contribution, and its finite part depends on a subtraction procedure. The thermodynamic approach based on subtracting the vacuum contribution for fixed values of temperature and dilaton charge at the "wall" gives (as in the leading-order black hole case) S= M/T for the entropy and zero value for the free energy F. We suggest that in order to establish a correspondence with a non-vanishing matrix model result for F one may need an alternative reparametrization-invariant subtraction procedure using analogy with non-critical string theory (i.e. replacing the spatial coordinate by the dilaton field). The subtraction of the dilaton divergence then produces a finite value for the free energy. We also propose a microscopic estimate for the entropy and energy of the black hole based on the contribution of non-singlet states of the matrix model.Comment: 25 pages, lanlma

Conformal Invariance = Finiteness and Beta Deformed N=4 SYM Theory

We claim that if by a choice of the couplings the theory can be made conformally invariant (vanishing of the beta functions) it is automatically finite and vice versa. This is demonstrated by explicit example in supersymmetric gauge theory. The formalism is then applied to the beta deformed ${\cal N}=4$ SYM theory and it is shown that the requirement of conformal invariance = finiteness can be achieved for any complex parameter of deformations.Comment: 15 pages, Latex, 1 figure axodraw styl