Hidden Interactions of Sterile Neutrinos As a Probe For New Physics

Recent results from neutrino experiments show evidence for light sterile neutrinos which do not have any Standard Model interactions. In this work we study the hidden interaction of sterile neutrinos with an "MeV scale" gauge boson (the $\nu_s$HI model) with mass $M_X$ and leptonic coupling $g^\prime_l$. By performing an analysis on the $\nu_s$HI model using the data of the MINOS neutrino experiment we find that the values above $G_X/G_F=92.4$ are excluded by more than $2\sigma$ C.L., where $G_F$ is the Fermi constant and $G_X$ is the field strength of the $\nu_s$HI model. Using this model we can also probe other new physics scenarios. We find that the region allowed by the $(g-2)_\mu$ discrepancy is entirely ruled out for $M_X\lesssim 100$ MeV. Finally, the secret interaction of sterile neutrinos has been to solve a conflict between the sterile neutrinos and cosmology. It is shown here that such an interaction is excluded by MINOS for $g^\prime_s> 1.6\times10^{-2}$. This exclusion, however, does depend on the value of $g_l^{\prime}$.Comment: 11 pages, 2 figures, Improved version with new figures and further details. Accepted in PR

TRACE-derived temperature and emission measure profiles along long-lived coronal loops: the role of filamentation

In a recent letter (ApJ 517, L155) Lenz et al. have shown the evidence of uniform temperature along steady long coronal loops observed by TRACE in two different passbands (171 A and 195 A filters). We propose that such an evidence can be explained by the sub-arcsecond structuring of the loops across the magnetic field lines. In this perspective, we present a model of a bundle of six thin parallel hydrostatic filaments with temperature stratification dictated by detailed energy balance and with temperatures at their apex ranging between 0.8 and 5 MK. If analyzed as a single loop, the bundle would appear isothermal along most of its length.Comment: 9 pages, 4 figs, LaTeX text, PostScript figure

Deep ROSAT-HRI observation of the elliptical galaxy NGC 1399

We present the preliminary results of a deep (167 ks) ROSAT HRI observation of the cD galaxy NGC1399 in the Fornax cluster. We find, in agreement with previous observations, an extended (41 Kpc adopting a distance of 19 Mpc) gaseous halo with a luminosity of L_X=(4.41\pm 0.04)x10^{41} erg/s. The 5 arcsec resolution of the data allows us to detect a very complex and asymmetric structure of the halo with respect to the optical galaxy. Moreover the analysis of the radial structure reveals the presence of a multi-component profile not consistent with a simple King model over the whole 40 Kpc. We do not detect the presence of a central source and pose an upper limit to the luminosity of a possible active nucleus. Due to the length of the observation, comparable to that of a deep survey, we detect a large number of sources within the HRI FOV, in slight excess with respect to the estimates based on previous surveys. We study the flux distribution of the sources, their temporal behaviour and their spatial distribution with respect to the central galaxy.Comment: 15 pages, 10 figures (6 in color), 1 table; uses subfigure.sty, supertabular.sty, lscape.sty, color.sty; To be published in the proceeding of "X-ray Astronomy 2000" (Mondello (Palermo), September 2000

Revising Limits on Neutrino-Majoron Couplings

Any theory that have a global spontaneously broken symmetry will imply the existence of very light neutral bosons or massless bosons (sometimes called Majorons). For most of these models we have neutrino-Majoron couplings, that appear as additional branching ratios in decays of mesons and leptons. Here we present an updated limits on the couplings between the electron, muon and tau neutrinos and Majorons. For such we analyze the possible effects of Majoron emission in both meson and lepton decays. In the latter we also include an analysis of the muon decay spectrum. Our results are $|g_{e\alpha}|^{2}<5.5x10^{-6}$, $|g_{\mu\alpha}|^{2}<4.5x10^{-5}$ and $|g_{\tau\alpha}|^{2}<5.5x10^{-2}$ at 90 % C. L., where $\alpha=e,\mu,\tau$.Comment: 12 pages, 5 figure

Atmospheric neutrinos: LMA oscillations, Ue3 induced interference and CP-violation

We consider oscillations of the low energy (sub-GeV sample) atmospheric neutrinos in the three neutrino context. We present the semi-analytic study of the neutrino evolution and calculate characteristics of the e-like events (total number, energy spectra and zenith angle distributions) in the presence of oscillations. At low energies there are three different contributions to the number of events: the LMA contribution (from electron-neutrino oscillations driven by the solar oscillation parameters), the Ue3-contribution proportional to s13**2, and the Ue3 - induced interference of the two amplitudes driven by the solar oscillation parameters. The interference term is sensitive to the CP-violation phase. We describe in details properties of these contributions. We find that the LMA, the interference and Ue3 contributions can reach 5 - 6%, 2 - 3% and 1 - 2 % correspondingly. An existence of the significant (> 3 - 5 %) excess of the e-like events in the sub-GeV sample and the absence of the excess in the multi-GeV range testifies for deviation of the 2-3 mixing from maximum. We consider a possibility to measure the deviation as well as the CP- violation phase in future atmospheric neutrino studies.Comment: 30 pages, RevTeX4.0, 11 figures; improved figure

Coronal loop hydrodynamics. The solar flare observedon November 12 1980 revisited: the UV line emission

We revisit a well-studied solar flare whose X-ray emission originating from a simple loop structure was observed by most of the instruments on board SMM on November 12 1980. The X-ray emission of this flare, as observed with the XRP, was successfully modeled previously. Here we include a detailed modeling of the transition region and we compare the hydrodynamic results with the UVSP observations in two EUV lines, measured in areas smaller than the XRP rasters, covering only some portions of the flaring loop (the top and the foot-points). The single loop hydrodynamic model, which fits well the evolution of coronal lines (those observed with the XRP and the \FeXXI 1354.1 \AA line observed with the UVSP) fails to model the flux level and evolution of the \OV 1371.3 \AA line.Comment: A&A, in press, 6 pages, 5 figure

Quantum mechanics explained

The physical motivation for the mathematical formalism of quantum mechanics is made clear and compelling by starting from an obvious fact - essentially, the stability of matter - and inquiring into its preconditions: what does it take to make this fact possible?Comment: 29 pages, 5 figures. v2: revised in response to referee comment

A Short Travel for Neutrinos in Large Extra Dimensions

Neutrino oscillations successfully explain the flavor transitions observed in neutrinos produced in natural sources like the center of the sun and the earth atmosphere, and also from man-made sources like reactors and accelerators. These oscillations are driven by two mass-squared differences, solar and atmospheric, at the sub-eV scale. However, longstanding anomalies at short-baselines might imply the existence of new oscillation frequencies at the eV-scale and the possibility of this sterile state(s) to mix with the three active neutrinos. One of the many future neutrino programs that are expected to provide a final word on this issue is the Short-Baseline Neutrino Program (SBN) at FERMILAB. In this letter, we consider a specific model of Large Extra Dimensions (LED) which provides interesting signatures of oscillation of extra sterile states. We started re-creating sensitivity analyses for sterile neutrinos in the 3+1 scenario, previously done by the SBN collaboration, by simulating neutrino events in the three SBN detectors from both muon neutrino disappearance and electron neutrino appearance. Then, we implemented neutrino oscillations as predicted in the LED model and also we have performed sensitivity analysis to the LED parameters. Finally, we studied the SBN power of discriminating between the two models, the 3+1 and the LED. We have found that SBN is sensitive to the oscillations predicted in the LED model and have the potential to constrain the LED parameter space better than any other oscillation experiment, for $m_{1}^D<0.1\,\text{eV}$. In case SBN observes a departure from the three active neutrino framework, it also has the power of discriminating between sterile oscillations predicted in the 3+1 framework and the LED ones.Comment: 21 pages, 6 figures, 2 table