118668829
Final model independent result of DAMA/LIBRA–phase1
The results obtained with the total exposure of 1.04 ton × yr collected by DAMA/LIBRA–phase1 deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. during 7 annual cycles (i.e. adding a further 0.17 ton × yr exposure) are presented. The DAMA/LIBRA–phase1 data give evidence for the presence of Dark Matter (DM) particles in the galactic halo, on the basis of the exploited model independent DM annual modulation signature by using highly radio-pure NaI(Tl) target, at 7.5σ C.L. Including also the first generation DAMA/NaI experiment (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles), the C.L. is 9.3σ and the modulation amplitude of the single-hit events in the (2–6) keV energy interval is: (0.0112±0.0012) cpd/kg/keV; the measured phase is (144±7) days and the measured period is (0.998±0.002) yr, values well in agreement with those expected for DM particles. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade.
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(...
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.
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.
10448516
Neutrino Mass and Baryon Asymmetry from Dirac Seesaw
We extend the visible content of the standard model (SM) with a hidden sector composed of three right-handed singlet neutrinos and one singlet Higgs. These extra singlets are charged under a new U(1)X gauge symmetry while the SM particles are not. Two heavy scalar doublets are introduced to play the role of the messengers between the visible and hidden sectors. The neutrinos naturally acquire tiny Dirac masses because the ratio of weak scale over the heavy messenger masses is highly suppressed. Furthermore, the heavy messengers simultaneously generate baryon asymmetry of the universe through their out-of-equilibrium CP-violating decays.
119248663
LHC Higgs signatures from extended electroweak gauge symmetry
A bstractWe study LHC Higgs signatures from the extended electroweak gauge symmetry SU(2) ⊗ SU(2) ⊗ U(1). Under this gauge structure, we present an effective UV completion of the 3-site moose model with ideal fermion delocalization, which contains two neutral Higgs states (h, H) plus three new gauge bosons (W′, Z′). We study the unitarity, and reveal that the exact E2 cancellation in the longitudinal VLVL scattering amplitudes is achieved by the joint role of exchanging both spin-1 new gauge bosons W′/Z′ and spin-0 Higgs bosons h/H. We identify the lighter Higgs state h with mass 125 GeV, and derive the unitarity bound on the mass of heavier Higgs boson H. The parameter space of this model is highly predictive. We study the production and decay signals of this 125 GeV Higgs boson h at the LHC. We demonstrate that the h Higgs boson can naturally have enhanced signals in the diphoton channel gg → h → γγ, while the event rates in the reactions gg → h → W W∗ and gg → h → ZZ∗ are generally suppressed relative to the SM expectation. Searching the h Higgs boson via the associated production and the vector boson fusions are also discussed for our model. We further analyze the LHC signals of the heavier Higgs boson H as a new physics discriminator from the SM. For wide mass-ranges of H, we derive constraints from the existing LHC searches, and study the discovery potential of H at the LHC (8 TeV) and LHC (14 TeV).
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.
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.
53070777
A ug 2 01 0 Gauge-Invariant Quantum Gravity Corrections to Gauge Couplings via Vilkovisky-DeWitt Method and Gravity Assisted Gauge Unification
Gravity is the weakest force in nature, and the gravitational interactions with all standard model (SM) particles can be well described by perturbative expansions of the Einstein-Hilbert action as an effective theory, all the way up to energies below the fundamental Planck scale. We use VilkoviskyDeWitt method to derive the first gauge-invariant nonzero gravitational power-law corrections to the running of gauge couplings, which make both Abel and non-Abel gauge interactions asymptotically free. We further demonstrate that the graviton-induced universal power-law runnings always assist the three SM gauge forces to reach unification around the Planck scale, irrespective of the detail of logarithmic corrections. We also compute the power-law corrections to the SM Higgs sector and derive modified triviality bound on the Higgs boson mass.