BMSSM Higgs Bosons at the Tevatron and the LHC

We study extensions of the Minimal Supersymmetric Standard Model (MSSM) with new degrees of freedom that couple sizably to the MSSM Higgs sector and lie in the TeV range. After integrating out the physics at the TeV scale, the resulting Higgs spectrum can significantly differ from typical supersymmetric scenarios, thereby providing a window Beyond the MSSM (BMSSM). Taking into account current LEP and Tevatron constraints, we perform an in-depth analysis of the Higgs collider phenomenology and explore distinctive characteristics of our scenario with respect to both the Standard Model and the MSSM. We propose benchmark scenarios to illustrate specific features of BMSSM Higgs searches at the Tevatron and the LHC.Comment: 18 pages, 9 figures; added parameters for each benchmark point, typos corrected, final version published by Phys. Rev.

SUSY Higgs bosons and beyond

We consider extensions of the Minimal Supersymmetric Standard Model (MSSM) where the extra degrees of freedom interact weakly with the Higgs sector. These models allow to relax the tension between the lower bound on the lightest CP even Higgs mass from direct LEP searches and the theoretical upper bound of the MSSM. We study the beyond MSSM (BMSSM) effects via an effective field-theory approach, assuming that the MSSM is valid up to a heavy physics scale M. We compute the masses, couplings and branching fractions of the Higgs sector, including all the relevant corrections up to order 1/M^2. We find that the collider phenomenology can be greatly different with respect to both the SM and the MSSM.Comment: Contribution to the XVIII International Workshop on Deep-Inelastic Scattering and Related Subjects, April 19 -23, 2010, Florence, Italy. 5 pages, 2 figure

Minimal Composite Higgs Models at the LHC

We consider composite Higgs models where the Higgs is a pseudo-Nambu Goldstone boson arising from the spontaneous breaking of an approximate global symmetry by some underlying strong dynamics. We focus on the SO(5) -> SO(4) symmetry breaking pattern, assuming the partial compositeness paradigm. We study the consequences on Higgs physics of the fermionic representations produced by the strong dynamics, that mix with the Standard Model (SM) degrees of freedom. We consider models based on the lowest-dimensional representations of SO(5) that allow for the custodial protection of the Z -> b b coupling, i.e. the 5, 10 and 14. We find a generic suppression of the gluon fusion process, while the Higgs branching fractions can be enhanced or suppressed compared to the SM. Interestingly, a precise measurement of the Higgs boson couplings can distinguish between different realizations in the fermionic sector, thus providing crucial information about the nature of the UV dynamics.Comment: 55 pages, 18 figures, References adde

The Planck Scale from Top Condensation

We propose a scenario in which the Planck scale is dynamically linked to the electroweak scale induced by top condensation. The standard model field content, without the Higgs, is promoted to a 5D warped background. There is also an additional 5D fermion with the quantum numbers of the right-handed top. Localization of the zero-modes leads, at low energies, to a Nambu-Jona-Lasinio model that also stabilizes the radion field dynamically thus explaining the hierarchy between the Planck scale and v_EW = 174 GeV. The top mass arises dynamically from the electroweak breaking condensate. The other standard model fermion masses arise naturally from higher-dimension operators, and the fermion mass hierarchies and flavor structure can be explained from the localization of the zero-modes in the extra dimension. If any other contributions to the radion potential except those directly related with electroweak symmetry breaking are engineered to be suppressed, the KK scale is predicted to be about two orders of magnitude above the electroweak scale rendering the model easily consistent with electroweak precision data. The model predicts a heavy (composite) Higgs with a mass of about 500 GeV and standard-model-like properties, and a vector-like quark with non-negligible mixing with the top quark and mass in the 1.6 - 2.9 TeV range. Both can be within the reach of the LHC. It also predicts a radion with a mass of a few GeV that is very weakly coupled to standard model matter.Comment: 41 pages, 7 figures; added references, minor changes in the electroweak precision constraints section; final version in PR

The infrared fixed point of the top quark mass and its implications within the MSSM

We analyse the general features of the Higgs and supersymmetric particle spectrum associated with the infrared fixed point solution of the top quark mass in the Minimal Supersymmetric Standard Model. We consider the constraints on the mass parameters, which are derived from the condition of a proper radiative electroweak symmetry breaking in the low and moderate \tan\beta regime. In the case of universal soft supersymmetry breaking parameters at the high energy scale, the radiative SU(2)_L \times U(1)_Y breaking, together with the top quark Yukawa fixed point structure imply that, for any given value of the top quark mass, the Higgs and supersymmetric particle spectrum is fully determined as a function of only two supersymmetry breaking parameters. We show that, for the interesting range of top quark mass values M_t\simeq 175\pm 10 GeV, both a light chargino and a light stop may be present in the spectrum. In addition, for a given top quark mass, the infrared fixed point solution of the top quark Yukawa coupling minimizes the value of the lightest CP-even Higgs mass m_h. The resulting upper bounds on m_h read m_h \leq 90 \;(105) \;(120) GeV for M_t \leq 165 \;(175) \;(185) GeV

Soft supersymmetry breaking parameters and minimal SO(10) unification

The minimal supersymmetric SO(10) model, in which not only the gauge but also the third generation fermion Yukawa couplings are unified, provides a simple and highly predictive theoretical scenario for the understanding of the origin of the low energy gauge interactions and fermion masses. In the framework of the MSSM, with universal soft supersymmetry breaking parameters at the grand unification scale, large values of the universal gaugino mass M_{1/2}\geq 300 GeV are needed in order to induce a proper breakdown of the electroweak symmetry. In addition, in order to obtain acceptable experimental values for both the pole bottom mass and the b\rightarrow s\gamma decay rate, even larger values of the gaugino masses are required. The model is strongly constrained by theoretical and phenomenological requirements and a heavy top quark, with mass M_t\geq 170 GeV, is hard to accomodate within this scheme. However, we show that to accommodate a top quark mass M_t\simeq180 GeV, it is sufficient to relax the condition of universality of the scalar soft SUSY breaking parameters at the grand unification scale. Still, the requirement of a heavy top quark demands a very heavy squark spectrum, unless specific relations between the soft SUSY breaking parameters are fulfilled.The minimal supersymmetric SO(10) model, in which not only the gauge but also the third generation fermion Yukawa couplings are unified, provides a simple and highly predictive theoretical scenario for the understanding of the origin of the low energy gauge interactions and fermion masses. In the framework of the MSSM, with universal soft supersymmetry breaking parameters at the grand unification scale, large values of the universal gaugino mass $M_{1/2}\geq 300$ GeV are needed in order to induce a proper breakdown of the electroweak symmetry. In addition, in order to obtain acceptable experimental values for both the pole bottom mass and the $b\rightarrow s\gamma$ decay rate, even larger values of the gaugino masses are required. The model is strongly constrained by theoretical and phenomenological requirements and a heavy top quark, with mass $M_t\geq 170$ GeV, is hard to accomodate within this scheme. However, we show that to accommodate a top quark mass $M_t\simeq180$ GeV, it is sufficient to relax the condition of universality of the scalar soft SUSY breaking parameters at the grand unification scale. Still, the requirement of a heavy top quark demands a very heavy squark spectrum, unless specific relations between the soft SUSY breaking parameters are fulfilled