119701812
Signals from dark Universe: DAMA/LIBRA at LNGS
The DAMA/LIBRA set-up (about 250 kg highly radiopure NaI(Tl) sensitive mass) is running at the Gran Sasso National Laboratory of the INFN. The first DAMA/LIBRA results point out the presence of a dark matter particle component in the galactic halo, as well as the former DAMA/NaI set-up; cumulatively the data support such evidence at 8.2σ CL and satisfy all the peculiarities of the dark matter annual modulation signature.
55768496
Particle Dark Matter in the galactic halo: results from DAMA/LIBRA
The DAMA/LIBRA experiment has a sensitive mass of about 250 kg highly radiopure NaI(Tl). It is running at the Gran Sasso National Laboratory of the INFN in Italy and is mainly devoted to the investigation of dark matter (DM) particles in the galactic halo by exploiting the model-independent DM annual modulation signature. The present DAMA/LIBRA and the former DAMA/NaI experiments (the first generation experiment having an exposed mass of about 100 kg) have thus far cumulatively released the results of data collected over 13 annual cycles (total exposure: 1.17 t year). They give model-independent evidence of the presence of DM particles in the galactic halo on the basis of the investigated DM signature at 8.9 sigma C.L. for the cumulative exposure. The main aspects of the obtained results are summarized and some comments are addressed.
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.
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.
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.
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.
55815188
Probing Gravitational Dark Matter
So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to gravitational interactions of the DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle s . It is a Z 2 odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, s 2 R , where s is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction s 2 R , together with Higgs-curvature nonminimal coupling term h H y HR , induces eective couplings between 2 and SM elds, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.
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.
17419673
Deconstruction and elastic {pi}{pi} scattering in Higgsless models
We study elastic pion-pion scattering in global linear moose models and apply the results to a variety of Higgsless models in flat and anti-de Sitter (AdS) space using the equivalence theorem. In order to connect the global moose to Higgsless models, we first introduce a block-spin transformation which corresponds, in the continuum, to the freedom to perform coordinate transformations in the Higgsless model. We show that it is possible to make an 'f-flat' deconstruction in which all of the f-constants f{sub j} of the linear moose model are identical; the phenomenologically relevant f-flat models are those in which the coupling constants of the groups at either end of the moose are small--corresponding to the global linear moose. In studying pion-pion scattering, we derive various sum rules, including one analogous to the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin (KSRF) relation, and use them in evaluating the low-energy and high-energy forms of the leading elastic partial-wave scattering amplitudes. We obtain elastic unitarity bounds as a function of the mass of the lightest KK mode and discuss their physical significance.
888469
Ideal fermion delocalization in five dimensional gauge theories
We discuss ideal delocalization of fermions in a bulk $SU(2)\ifmmode\times\else\texttimes\fi{}SU(2)\ifmmode\times\else\texttimes\fi{}U(1)$ Higgsless model with a flat or warped extra dimension. So as to make an extra dimensional interpretation possible, both the weak and hypercharge properties of the fermions are delocalized, with the $U(1{)}_{Y}$ current of left-handed fermions being correlated with the $SU(2{)}_{W}$ current. We find that (to subleading order) ideal fermion delocalization yields vanishing precision electroweak corrections in this continuum model, as found in corresponding theory-space models based on deconstruction. In addition to explicit calculations, we present an intuitive argument for our results based on Georgi's spring analogy. We also discuss the conditions under which the essential features of an $SU(2)\ifmmode\times\else\texttimes\fi{}SU(2)\ifmmode\times\else\texttimes\fi{}U(1)$ bulk gauge theory can be captured by a simpler $SU(2)\ifmmode\times\else\texttimes\fi{}SU(2)$ model.
119290289
Spontaneous mirror parity violation, common origin of matter and dark matter, and the LHC signatures
Existence of a mirror world in the Universe is a fundamental way to restore the observed parity violation in weak interactions and provides the lightest mirror nucleon as a unique GeV-scale dark matter particle candidate. The visible and mirror worlds share the same spacetime of the Universe and are connected by a unique space-inversion symmetry-the mirror parity (P). We conjecture that the mirror parity is respected by the fundamental interaction Lagrangian, and study its spontaneous breaking from minimizing the Higgs vacuum potential. The domain-wall problem is resolved by a unique soft-breaking linear term from the P-odd weak-singlet Higgs field. We also derive a constraint from big-bang nucleosynthesis. We then analyze the neutrino seesaw for both visible and mirror worlds, and demonstrate that the desired amounts of visible matter and mirror dark matter in the Universe arise from a common origin of CP violation in the neutrino sector via leptogenesis. We derive the Higgs mass spectrum and Higgs couplings with gauge bosons and fermions. We show their consistency with the direct Higgs searches and the indirect precision constraints. We further study the distinctive signatures of the predicted nonstandard Higgs bosons at the LHC. Finally, we analyze the direct detections of GeV-scale mirror dark matter by the TEXONO and CDEX experiments.