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.
124862840
DIRECT DETECTION OF DARK MATTER PARTICLES
2157347
On electromagnetic contributions in WIMP quests
The effect pointed out by A. B. Migdal in 1940's (hereafter named Migdal effect) has so far been usually neglected in the direct searches for WIMP Dark Matter candidates. This effect consists in the ionization and the excitation of bound atomic electrons induced by the recoiling atomic nucleus. In the present paper the related theoretical arguments are developed and some consequences of the proper accounting for this effect are discussed by some examples of practical interest.
117048271
First DAMA/LIBRA Results and Beyond
The DAMA project is an observatory for rare processes and it is operative deep underground at the Gran Sasso National Laboratory of the I.N.F.N. Its main apparatus is the DAMA/LIBRA set-up, consisting of ≃250 kg highly radiopure NaI(Tl) detectors. Its first results — obtained by exploiting over four annual cycles the model independent annual modulation signature for Dark Matter (DM) particles — confirm by those of the former DAMA/NaI, supporting the evidence for Dark Matter presence in the galactic halo at 8.2 σ C.L.. The DAMA/NaI and DAMA/LIBRA data, in fact, satisfy all the many peculiarities of the DM annual modulation signature. Neither systematic effects nor side reactions able to account for the observed modulation amplitude and to contemporaneously satisfy all the several requirements of the DM signature are available. Future perspectives are also addressed.
17529257
Direct detection of dark-matter particles
In this conference the model-independent result on the presence of 
dark-matter particles in the galactic halo obtained over seven annual cycles by the 
 100 kg highly radiopure NaI(Tl) DAMA/NaI has been presented and several corollary 
investigations have also been discussed. More recently the model-independent 
result obtained over the first four annual cycles by the second generation 250 kg 
highly radiopure NaI(Tl) DAMA/LIBRA set-up at the Gran Sasso National Laboratory 
of the INFN has also been released. Both the experiments have the unique 
feature to effectively investigate the presence of dark-matter particles in the galactic 
halo by exploiting the model-independent annual modulation signature. The 
data collected by the two experiments over eleven annual cycles for a total exposure 
of 0.82 ton × y have pointed out at 8.2σ CL a positive result; several corollary 
model-dependent quests for the candidate particle(s) and related astrophysical, nuclear 
and particle physics scenarios are under updating. The future experimental 
activity can give rise to many new interesting results.
118331572
A few final comments to arXiv:1210.7548[hep-ph]
A few final comments on arXiv:1210.7548 are given to confute incorrect arguments claimed there.
15162547
Quartic gauge boson couplings at linear colliders: Interplay of WWZ / ZZZ production and WW fusion
Abstract We study new physics effects to the quartic gauge boson couplings formulated by the electroweak chiral Lagrangian. Five next-to-leading order operators characterize the anomalous quartic gauge interactions which involve pure Goldstone boson dynamics for the electroweak symmetry breaking. We estimate the typical size of these couplings in different strongly-interacting models and examine the sensitivity to directly probing them via the WWZ / ZZZ triple gauge boson production at the high energy linear colliders. The important roles of polarized e − and e + beams are stressed. We then compare the results with those from the W -pair production of the WW -fusion processes, and analyze the interplay of these two production mechanisms for an improved probe of the quartic gauge boson interactions.
118875522
Unitarity of the higher-dimensional standard model
Abstract We study the unitarity of the standard model (SM) in higher dimensions. We show that the essential features of SM unitarity remain after compactification, and place bounds on the highest Kaluza–Klein (KK) level N KK and the Higgs mass m H in the effective four-dimensional (4d) low-energy theory. We demonstrate these general observations by explicitly analyzing the effective 4d KK theory of a compactified 5d SM on S 1 / Z 2 . The nontrivial energy cancellations in the scattering of longitudinal KK gluons or KK weak bosons, a consequence of the geometric Higgs mechanism, are verified. In the case of the electroweak gauge bosons, the longitudinal KK states also include a small mixture from the KK Higgs excitations. With the analyses before and after compactification, we derive the strongest bounds on N KK from gauge KK scattering. 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. As a consequence, we show that the GUT scale in the 5d minimal SUSY GUT cannot be lower than about 10 14  GeV.
5881766
Scale of mass generation for Majorana neutrinos
Scales of mass generation for Majorana neutrinos (as well as quarks and leptons) can be probed from high energy 2 → n inelastic scattering involving a multiple longitudinal gauge boson final state. We demonstrate that the unitarity of 2 → n scattering puts the strongest new upper limit on the scale of fermion mass generation, independent of the electroweak symmetry breaking scale v = ( √ 2GF) 1 2 . Strikingly, for Majorana neutrinos (quarks and leptons), we find that the strongest 2 → n limits fall in a narrow range, 136 − 170 TeV (3 − 107 TeV) with n = 20 − 24 (n = 2 − 12), depending on the observed fermion masses. Physical implications are discussed.
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.
17603783
Oblique Corrections in Deconstructed Higgsless Models
In this talk, using deconstruction, we analyze the form of the corrections to the electroweak interactions in a large class of ``Higgsless'' models of electroweak symmetry breaking, allowing for arbitrary 5-D geometry, position-dependent gauge coupling, and brane kinetic energy terms. Many models considered in the literature, including those most likely to be phenomenologically viable, are in this class. By analyzing the asymptotic behavior of the correlation function of gauge currents at high momentum, we extract the exact form of the relevant correlation functions at tree-level and compute the corrections to precision electroweak observables in terms of the spectrum of heavy vector bosons. We determine when nonoblique corrections due to the interactions of fermions with the heavy vector bosons become important, and specify the form such interactions can take. In particular we find that in this class of models, so long as the theory remains unitary, S - 4 c^2_W T > O(1), where S and T are the usual oblique parameters.