9977745
Probing Higgs bosons with large bottom Yukawa coupling at hadron colliders
The small mass of the bottom quark, relative to its weak isospin partner, the top quark, makes the bottom an effective probe of new physics in Higgs and top sectors. We study the Higgs boson production associated with bottom quarks, p{bar p}/pp{r_arrow}{phi}b{bar b}{r_arrow}b{bar b}b{bar b}, at the Fermilab Tevatron and the CERN LHC. We find that strong and model-independent constraints on the size of the {phi}-b-{bar b} coupling can be obtained for a wide range of Higgs boson masses. Their implications for the composite Higgs models with strong dynamics associated with the third family quarks (such as the top-quark condensate or top-color models with naturally large bottom Yukawa couplings), and for the supersymmetric models with large tan{beta}, are analyzed. We conclude that the Tevatron and the LHC can put stringent bounds on these models, if the {phi}b{bar b} signal is not found. {copyright} {ital 1999} {ital The American Physical Society}
119248851
General Sum Rules for WW Scattering in Higgsless Models: Equivalence Theorem and Deconstruction Identities
We analyze inelastic 2{yields}2 scattering amplitudes for gauge bosons and Nambu-Goldstone bosons in deconstructed Higgsless models. Using the (KK) equivalence theorem in 4D (5D), we derive a set of general sum rules among the boson masses and multiboson couplings that are valid for arbitrary deconstructed models. Taking the continuum limit, our results naturally include the 5D Higgsless model sum rules for arbitrary 5D geometry and boundary conditions; they also reduce to the elastic sum rules when applied to the special case of elastic scattering. For the case of linear deconstructed Higgsless models, we demonstrate that the sum rules can also be derived from a set of general deconstruction identities and completeness relations. We apply these sum rules to the deconstructed 3-site Higgsless model and its extensions; we show that in 5D ignoring all higher KK modes (n>1) is inconsistent once the inelastic channels become important. Finally, we discuss how our results generalize beyond the case of linear Higgsless 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.
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 $n_s \sim 0.96$.
73581246
Unitarity of deconstructed five-dimensional Yang–Mills theory
Abstract The low-energy properties of a compactified five-dimensional gauge theory can be reproduced in a four-dimensional theory with a replicated gauge group and an appropriate gauge symmetry breaking pattern. The lightest vector bosons in these “deconstructed” or “remodeled” theories have masses and couplings approximately equal to those of the Kaluza–Klein tower of massive vector states present in a compactified higher-dimensional gauge theory. We analyze the unitarity of low-energy scattering of the massive vector bosons in a deconstructed theory, and examine the relationship between the scale of unitarity violation and the scale of the underlying chiral symmetry breaking dynamics which breaks the replicated gauge groups. As in the case of compactified five-dimensional gauge theories, low-energy unitarity is ensured through an interlacing cancellation among contributions from the tower of massive vector bosons. We show that the behavior of these scattering amplitudes is manifest without such intricate cancellations in the scattering of the would-be Goldstone bosons of the deconstructed theory. Unlike compactified five-dimensional gauge theories, the amplitude for longitudinal vector boson scattering in deconstructed theories does grow with energy, though this effect is suppressed by 1/( N +1), with N +1 being the number of replicated gauge groups.
27494349
DARK MATTER INVESTIGATION BY DAMA AT GRAN SASSO
Experimental observations and theoretical arguments at Galaxy and larger scales have suggested that a large fraction of the Universe is composed by Dark Matter particles. This has motivated the DAMA experimental efforts to investigate the presence of such particles in the galactic halo by exploiting a model independent signature and very highly radiopure setup in deep underground. Few introductory arguments are summarized before presenting a review of the present model independent positive results obtained by the DAMA/NaI and DAMA/LIBRA setups at the Gran Sasso National Laboratory of the INFN. Implications and model dependent comparisons with other different kinds of results will be shortly addressed. Some arguments put forward in literature will be confuted.
121164344
Search for solar axions by Primakoff effect in NaI crystals
The results of a search for possible signal due to Primakoff coherent conversion of solar axions into photons in NaI(Tl) are presented. The experiment has been carried out at the Gran Sasso National Laboratory of INFN; the used statistics is 53437 kg day. The presently most stringent experimental limit on g(a gamma gamma) from this process is obtained: g(a gamma gamma) < 1.7 x 10(-9) GeV-1 (90% C.L.). In particular, the axion mass window m(a) greater than or similar to 0.03 eV, not accessible by other direct methods, is explored and KSVZ axions with mass larger than 4.6 eV are excluded at 90% C.L. (C) 2001 Elsevier Science B.V. All rights reserved.
54078935
No role for muons in the DAMA annual modulation results
This paper gathers arguments and reasons why muons surviving the Gran Sasso mountain cannot mimic the Dark Matter annual modulation signature exploited by the DAMA/NaI and DAMA/LIBRA experiments. A number of these items have already been presented in individual papers. Further arguments have been addressed here in order to present a comprehensive collection and to enable a wider community to correctly approach this point.
122178650
New search for processes violating the Pauli exclusion principle in sodium and in iodine
In this paper a new search for non-Paulian nuclear processes, i.e. processes normally forbidden by the Pauli Exclusion Principle (PEP), is presented. It has been carried out at the Gran Sasso National Laboratory of the INFN by means of the highly radiopure DAMA/LIBRA set-up (sensitive mass of about 250 kg highly radiopure NaI(Tl)). In particular, a new improved upper limit for the spontaneous non-Paulian emission rate of protons with energy Ep≥ 10 MeV in 23Na and 127I has been obtained: 1.63 × 10−33 s−1 (90% C.L.). The corresponding limit on the relative strength (δ2) for the searched non-Paulian transition is δ2≲(3–4)×10−55 (90% C.L.). Moreover, PEP-violating electron transitions in iodine atoms have also been investigated. Lifetimes shorter than 4.7×1030 s are excluded at 90% C.L.; this allows us to derive the limit δe2<1.28×10−47 (90% C.L.). This latter limit can also be related to a possible finite size of the electron in composite models of quarks and leptons providing superficial violation of the PEP; the obtained upper limit on the electron size is r0<5.7×10−18 cm (energy scale of E≳3.5 TeV).
117876638
Investigation on possible diurnal effects induced by Dark Matter particles
Possible diurnal effects in the low-energy counting rate, measured by the large-mass highly radiopure NaI(Tl) DAMA set-up at the Gran Sasso National Laboratory of INFN, have been investigated. The results achieved by considering a possible dependence of the diurnal rate on sidereal time have further constrained Dark Matter particle candidates with high cross-section. Moreover, the presence of possible diurnal effects of unknown nature correlated with the solar time have been excluded.