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.
124862840
DIRECT DETECTION OF DARK MATTER PARTICLES
118311956
DAMA investigations on Dark Matter at Gran Sasso: results and perspectives
The DAMA/NaI experiment (≃ 100 kg highly radiopure NaI(Tl)) at the Gran Sasso National Laboratory of the I.N.F.N. had the unique feature to effectively investigate the presence of Dark Matter particles in the galactic halo by exploiting the model independent annual modulation signature. A total exposure of more than 105 kg × day, collected over seven annual cycles, has pointed out at 6.3 σ C.L. an effect which satisfies all the many peculiarities of the signature. Neither systematics nor side reactions able to account for the observed effect were found. No experiment whose result can be directly compared in a model independent way with the experimental one of DAMA/NaI is available so far. Searches in space experiments are not in contradiction with DAMA/NaI. Several (but still few with respect to the possibilities) corollary model dependent quests for the candidate particle have also been carried out; others are in progress. At present the second generation DAMA/LIBRA set‐up (≃ 250 kg highly radiopure NaI(...
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.
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.
49241293
New top-flavor models with a seesaw mechanism
A new class of models is constructed in which the third family quarks, but not leptons, experience a new SU(2) or U(1) gauge force. Anomaly cancellation enforces the introduction of spectator quarks so that top and bottom quark masses are naturally generated via a seesaw mechanism. We find the new contributions to the (S,T,U) parameters and Zb{bar b}vertex to be generically small. We analyze how the reasonable flavor mixing pattern can be generated to ensure the top-seesaw mechanism and sufficiently suppress flavor-changing effects for light quarks. Collider signatures for the light Higgs boson and top quark are also discussed.
11320645
Single charged Higgs boson production in polarized photon collisions and the probe of new physics
We study single charged Higgs boson production in photon-photon collisions as a probe of the new dynamics of Higgs interactions. This is particularly important when the mass ${(M}_{{H}^{\ifmmode\pm\else\textpm\fi{}}})$ of charged Higgs bosons ${(H}^{\ifmmode\pm\else\textpm\fi{}})$ is relatively heavy and above the kinematic limit of the pair production ${(M}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}g\sqrt{s}/2).$ We analyze the cross sections of single charged Higgs boson production from the photon-photon fusion processes $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}{\ensuremath{\tau}}^{\ensuremath{-}}\overline{\ensuremath{\nu}}{H}^{+}$ and $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}b\overline{c}{H}^{+},$ as motivated by the minimal supersymmetric standard model and the dynamical top-color model. We find that the cross sections at such a $\ensuremath{\gamma}\ensuremath{\gamma}$ collider can be sufficiently large even for ${M}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}g\sqrt{s}/2,$ and is typically one to two orders of magnitude higher than that at its parent ${e}^{\ensuremath{-}}{e}^{+}$ collider. We further demonstrate that the polarized photon beams can provide an important means to determine the chirality structure of Higgs Yukawa interactions with the fermions.
119095037
Collider tests of compact space dimensions using weak gauge bosons
We present collider tests of the recent proposal for weak-scale quantum gravity due to new large compact space dimensions in which only the graviton $(G)$ propagates. We show that the existing high precision LEP-I $Z$-pole data can impose nontrivial constraints on the scale of the new dimensions, via the decay mode $Z\ensuremath{\rightarrow}f\overline{f}+G$ $(f\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}q,\ensuremath{\ell})$. These bounds are comparable to those obtained at high energy colliders and provide the first sensitive probe of the scalar graviton. We also study $W(Z)+G$ production and the anomalous $\mathrm{WW}(\mathrm{ZZ})$ signal from virtual $G$-states at the Fermilab Tevatron and compare them with the LEP-I bound and those from LEP-II and future linear colliders.
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.