118074881
Search for TeV Gamma Ray Bursts from Evaporating Primordial Black Holes
Data taken with ACT2 and ACT3 between 1995 and 1997 are used to search for 0.1 s bursts of TeV gamma ray from evaporating primordial black holes (PBHs). There is no evidence for such bursts in the dataset. Using the result, the upper limit of 3×108pc-3yr-1 on the rate-density of evaporating PBHs is set in the vicinity of the solar system at a 99% confidence level.
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(...
124862840
DIRECT DETECTION OF DARK MATTER PARTICLES
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.
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.
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.
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.
118867052
Constraining Astrophysical Neutrino Flavor Composition from Leptonic Unitarity
The recent IceCube observation of ultra-high-energy astrophysical neutrinos has begun the era of neutrino astronomy. In this work, using the unitarity of leptonic mixing matrix, we derive nontrivial unitarity constraints on the avor composition of astrophysical neutrinos detected by IceCube. Applying leptonic unitarity triangles, we deduce these unitarity bounds from geometrical conditions, such as triangular inequalities. These new bounds generally hold for three avor neutrinos, and are independent of any experimental input or the pattern of leptonic mixing. We apply our unitarity bounds to derive general constraints on the avor compositions for three types of astrophysical neutrino sources (and their general mixture), and compare them with the IceCube measurements. Furthermore, we prove that for any sources without neutrinos, a detected ux ratio < 1=4 will require the initial avor
9048226
Scales of mass generation for quarks, leptons, and majorana neutrinos.
We study 2-->n inelastic fermion-(anti)fermion scattering into multiple longitudinal weak gauge bosons and derive universal upper bounds on the scales of fermion mass generation by imposing unitarity of the S matrix. We place new upper limits on the scales of fermion mass generation, independent of the electroweak symmetry breaking scale. Strikingly, we find that the strongest 2-->n limits fall in a narrow range, 3-170 TeV (with n=2-24), depending on the observed fermion masses.
119424428
Unitarity of Little Higgs models signals new physics of UV completion
Abstract The “Little Higgs” opens up a new avenue for natural electroweak symmetry breaking in which the standard model Higgs particle is realized as a pseudo-Goldstone boson and thus is generically light. The symmetry breaking structure of the Little Higgs models predicts a large multiplet of (pseudo-)Goldstone bosons and their low energy interactions below the ultraviolet (UV) completion scale Λ ∼4 πf ∼ O (10) TeV, where f is the Goldstone decay constant. We study unitarity of the Little Higgs models by systematically analyzing the high energy scatterings of these (pseudo-)Goldstone bosons. We reveal that the collective effect of the Goldstone scatterings via coupled channel analysis tends to push the unitarity violation scale Λ U significantly below the conventional UV scale Λ ∼4 πf as estimated by naive dimensional analysis (NDA). Specifically, Λ U ∼(3–4) f , lying in the multi-TeV range for f ∼1 TeV. We interpret this as an encouraging sign that the upcoming LHC may explore aspects of Little Higgs UV completions, and we discuss some potential signatures. The meanings of the two estimated UV scales Λ U (from unitarity violation) and Λ (from NDA) together with their implications for an effective field theory analysis of the Little Higgs models are also discussed.
6798711
Deconstructed Higgsless models with one-site delocalization
In this note we calculate the form of electroweak corrections in deconstructed Higgsless models for the case of a fermion whose weak properties arise from two adjacent $SU(2)$ groups on the deconstructed lattice. We show that, as recently proposed in the continuum, it is possible for the value of the electroweak parameter $\ensuremath{\alpha}S$ to be small in such a model. In addition, by working in the deconstructed limit, we may directly evaluate the size of off-$Z$-pole electroweak corrections arising from the exchange of Kaluza-Klein modes; this has not been studied in the continuum. The size of these corrections is summarized by the electroweak parameter $\ensuremath{\alpha}\ensuremath{\delta}$. In one-site delocalized Higgsless models with small values of $\ensuremath{\alpha}S$, we show that the amount of delocalization is bounded from above, and must be less than 25% at 95% C.L. We discuss the relation of these calculations to our previous calculations in deconstructed Higgsless models, and to models of extended technicolor. We present numerical results for a four-site model, illustrating our analytic calculations.