119045187
Higgs Boson with Large Bottom Yukawa Coupling at Tevatron and LHC
We study the discovery reach of the Tevatron and the LHC for detecting a Higgs boson (h), predicted in composite models of the electroweak symmetry breaking or in supersymmetric theories, with an enhanced b-quark Yukawa coupling via p \bar{p} / p p \to b \bbar h (\to b \bbar) + X. Our analysis shows that studying this process at the Tevatron Run II or the LHC can provide strong constraints on these models.
119518408
New Method for Detecting Charged Scalars at Colliders
We propose a new method for detecting a charged (pseudo)scalar at colliders, based upon the observation that its Yukawa coupling to charm and bottom quarks can be large due to a significant mixing of the top and charm quarks. After analyzing the typical flavor mixing allowed by low energy data in the topcolor and the generic two-Higgs doublet models, we study the physics potential of the Tevatron, LHC, and linear colliders for probing such an $s$-channel charged resonance via the single-top (as well as ${W}^{\ifmmode\pm\else\textpm\fi{}}{h}^{0}$) production. We show that studying its detection at colliders can also provide information on the dynamics of flavor-changing neutral current phenomena.
7672098
Unitarity in Higher Dimensions and Gauge Unification
Unitarity of the 4d standard model is ensured by the conventional Higgs mechanism with a fundamental spin-0 Higgs boson, responsible for gauge boson mass-generations. On the contrary Kaluza-Klein (KK) compactification of extra spatial dimensions can geometrically realize the gauge boson mass generation without invoking a fundamental Higgs scalar. We reveal that massive gauge boson scattering in the compactified theories is unitary at low energies, and the unitarity violation is {\it delayed} to the intrinsic ultraviolet (UV) scale of the higher dimensional gauge theory. We demonstrate that this is a generic consequence of the ``geometric Higgs mechanism'' (GHM), manifested via Kaluza-Klein equivalence theorem (KK-ET). We further show that the presence of many gauge KK states below the UV cutoff scale imposes strong bounds on the highest KK level (N_KK). Applying these bounds to higher-dimensional SUSY GUTs implies that only a small number of KK states can be used to accelerate gauge coupling unification, and suggests that the GUT scale in the 5d minimal SUSY SU(5) is above 10^{14} GeV.
119496
The Equivalence theorem and its radiative correction - free formulation for all R(xi) gauges
The electroweak equivalence theorem quantitatively connects the physical amplitudes of longitudinal massive gauge bosons to those of the corresponding {ital unphysical} would-be Goldstone bosons. Its precise form depends on both the gauge-fixing condition and the renormalization scheme. Our previous modification-free schemes have applied to a broad class of R{sub {xi}} gauges including the `t Hooft{endash}Feynman gauge but excluding the Landau gauge. In this paper we construct a new renormalization scheme in which the radiative modification factor C{sub mod}{sup a} is equal to unity for all R{sub {xi}} gauges, including both `t Hooft{endash}Feynman and Landau gauges. This scheme makes C{sub mod}{sup a} equal to unity by specifying a convenient subtraction condition for the would-be Goldstone boson wave function renormalization constant Z{sub {phi}{sup a}}. We build the new scheme for both the standard model and the effective Lagrangian formulated electroweak theories (with either linearly or nonlinearly realized symmetry-breaking sector). Based upon these, a new prescription, called the {open_quotes}divided equivalence theorem,{close_quotes} is further proposed for extending the high energy region applicable to the equivalence theorem. {copyright} {ital 1997} {ital The American Physical Society}
118551349
New Higgs Inflation in a No-Scale Supersymmetric SU(5) GUT
Higgs inflation is attractive because it identifies the inflaton with the electroweak Higgs boson. In this work, we construct a new class of supersymmetric Higgs inflationary models in the no-scale supergravity with an SU(5) GUT group. Extending the no-scale Kahler potential and SU(5) GUT superpotential, we derive a generic potential for Higgs inflation that includes the quadratic monomial potential and a Starobinsky-type potential as special limits. This type of models can accommodate a wide range of the tensor-to-scalar ratio $r = O(10^{-3}-10^{-1})$, as well as a scalar spectral index $n_s \sim 0.96$.
7781549
Top quark seesaw model, vacuum structure, and electroweak precision constraints
We present a complete study of the vacuum structure of top quark seesaw models of the electroweak symmetry breaking, including bottom quark mass generation. Such models emerge naturally from bosonic extra dimensions. We perform a systematic gap equation analysis and develop an improved broken phase formulation for including exact seesaw mixings. The composite Higgs boson spectrum is studied in the large-${N}_{c}$ fermion-bubble approximation and an improved renormalization group approach. The theoretically allowed parameter space is restrictive, leading to well-defined predictions. We further analyze the electroweak precision constraints. Generically, a heavy composite Higgs boson with a mass of $\ensuremath{\sim}1 \mathrm{TeV}$ is predicted, yet fully compatible with the precision data.
121506888
Technical aspects in dark matter direct detection
In the field of dark matter direct detection, on the one hand, it is predicted by theoretical models that many dark matter candidates and scenarios are possible. On the other hand, a variety of detectors has been proposed, but most of them — by the fact — are still at R&D stage. Such a situation leads to some considerations on technical aspects on dark matter direct detection.
121818290
Investigating the DAMA annual modulation data in the framework of inelastic dark matter
Abstract. In this paper, the model independent annual modulation effect observed by DAMA during four independent experiments of one annual cycle each (57986 kg $\times$ day total statistics) is analysed in terms of a particle dark matter candidate which can only inelastically scatter by making a transition to a slightly heavier state, as previously suggested in the literature.
123155784
Particle dark matter in the galactic halo: Recent results from DAMA/LIBRA
The present DAMA/LIBRA experiment and the former DAMA/NaI have cumulatively released so far the results obtained with the data collected over 13 annual cycles (total exposure: 1.17 ton per year). They give a model independent evidence of the prese nce of dark matter particles in the galactic halo on the basis of the dark matter annual modulation signature at 8.9 sigma C.L. for the cumulative exposure.
121568552
New limits on the nuclear levels excitation of I-127 and Na-23 during charge nonconservation
New lifetime limits on the charge nonconserving electron capture with excitation of I-127 and Na-23 nuclear levels are established. The statistics used is 34 866 kg day; it has been collected deep underground at the Gran Sasso National Laboratory of INFN by the highly radiopure similar or equal to 100 kg DAMA NaI(Tl) setup. These new limits are in the range (1.5-2.4) X 10(23) y, up to two orders of magnitude higher than the ones previously available. Stringent restrictions on the relative strengths of the charge nonconserving processes are derived: epsilon(W)(2)<9.6 X 10(-26) and epsilon(gamma)(2)<1.2 X 10(-40) (90% C.L.). [S0556-2813(99)01612-X].
7994047
INVESTIGATION ON LIGHT DARK MATTER
Some extensions of the Standard Model provide Dark Matter candidate particles with sub-GeV mass. These Light Dark Matter particles have been considered for example in Warm Dark Matter scenarios (e.g. the keV scale sterile neutrino, axino or gravitino). Moreover, MeV scale DM candidates have been proposed in supersymmetric models and as source of the 511 keV line from the Galactic center. In this paper the possibility of direct detection of a Light Dark Matter candidate is investigated considering the inelastic scattering processes on the electron or on the nucleus targets. Some theoretical arguments are developed and related phenomenological aspects are discussed. Allowed volumes and regions for the characteristic phenomenological parameters of the considered scenarios are derived from the DAMA/NaI annual modulation data.