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.
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.
54990227
Higgsless Models: Lessons from Deconstruction
This talk reviews recent progress in Higgsless models of electroweak symmetry breaking, and summarizes relevant points of model‐building and phenomenology.
122894759
A detailed study of the interaction mechanisms for Si(Li) detector response functions by the direct Monte Carlo approach
Abstract A direct Monte Carlo (DMC) calculation of the complete response functions of Si(Li) detectors for low energy X-rays (keV) is proposed. Interaction mechanisms for X-rays in the sensitive volume of the detector and in the surrounding material are investigated in detail. Response functions at several energy values are calculated and compared with the corresponding experimental ones. The present approach uses a detailed simulation of individual interactions rather than the simple range formulation used by Gardner et al. [Nucl. Instr. and Meth. A242 (1986) 399] and gives better results in some cases. The physical model and calculation method presented here can be applied widely to low energy X-ray fluorescence analysis and other complicated photon spectrum analyses. In principle it is also suited for Ge detectors.
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.
13928631
Multigauge-boson vertices and chiral Lagrangian parameters in Higgsless models with ideal fermion delocalization
Higgsless models with fermions whose $SU(2)$ properties are ``ideally delocalized,'' such that the fermion's probability distribution is appropriately related to the $W$ boson wave function, have been shown to minimize deviations in precision electroweak parameters. As contributions to the $S$ parameter vanish to leading order, current constraints on these models arise from limits on deviations in multi-gauge-boson vertices. We compute the form of the triple and quartic gauge-boson vertices in these models and show that these constraints provide lower bounds only of the order of a few hundred GeV on the masses of the lightest $KK$ resonances. Higgsless models with ideal fermion delocalization provide an example of extended electroweak gauge interactions with suppressed couplings of fermions to extra gauge bosons, and these are the only models for which triple-gauge-vertex measurements provide meaningful constraints. We relate the multigauge couplings to parameters of the electroweak chiral Lagrangian, and the parameters obtained in these $SU(2)\ifmmode\times\else\texttimes\fi{}SU(2)$ models apply equally to the corresponding five-dimensional gauge theory models of QCD. We also discuss the collider phenomenology of the $KK$ resonances in models with ideal delocalization. These resonances are found to be fermiophobic, therefore traditional direct collider searches are not sensitive to them and measurements of gauge-boson scattering will be needed to find them.
17766827
Investigating electron interacting dark matter
Some extensions of the standard model provide dark matter candidate particles which can have a dominant coupling with the lepton sector of the ordinary matter. Thus, such dark matter candidate particles (chi(0)) can be directly detected only through their interaction with electrons in the detectors of a suitable experiment, while they are lost by experiments based on the rejection of the electromagnetic component of the experimental counting rate. These candidates can also offer a possible source of the 511 keV photons observed from the galactic bulge. In this paper this scenario is investigated. Some theoretical arguments are developed and related phenomenological aspects are discussed. Allowed intervals and regions for the characteristic phenomenological parameters of the considered model and of the possible mediator of the interaction are also derived considering the DAMA/NaI data.
117867179
Comment on 'On an unverified nuclear decay and its role in the DAMA experiment' (arXiv:1210.5501)
We briefly remind references and arguments, already discussed in the past, which confute erroneous claims in arXiv:1210.5501.
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].
118601021
New search for correlated e+e- pairs in the $ \alpha$ decay of 241Am
Abstract.A new search for production of correlated $e^{+}e^{-}$ pairs in the $\alpha$ decay of 241Am has been carried out deep underground at the Gran Sasso National Laboratory of the INFN by using pairs of NaI(Tl) detectors of the DAMA/LIBRA set-up. The experimental data show an excess of double coincidences of events with energy around 511keV in faced pairs of detectors, which are not explained by known side reactions. This measured excess gives a relative activity $\lambda=(4.70\pm 0.63)\times 10^{-9}$ for the Internal Pair Production (IPP) with respect to the alpha decay of 241Am; this value is of the same order of magnitude as previous determinations. In a conservative approach the upper limit $\lambda < 5.5\times 10^{-9}$ (90% C.L.) can be derived. It is worth noting that this is the first result on IPP obtained in an underground experiment, and that the $ \lambda$ value obtained in the present work is independent of the live-time estimate.
166163535
RESULTS FROM DAMA/LIBRA