Search results for "Speed"
showing 10 items of 876 documents
The termination region of high-mass microquasar jets
2011
The environment of high-mass X-ray binaries can be characterized either by the SNR that forms these systems, or by the wind from the companion massive star. These regions should be tenuous but very hot, and surrounded by a dense and cold shocked ISM shell. The interaction between the jet and such a complex medium, also affected by the system proper motion, can lead to very different jet termination structures. The evolution of the jet termination regions during the life of a high-mass microquasar is simulated to improve the present understanding of these structures. Also, the evolving emission characteristics are modeled to inform potential observational campaigns for this class of object. …
Search for a Lorentz-violating sidereal signal with atmospheric neutrinos in IceCube
2010
A search for sidereal modulation in the flux of atmospheric muon neutrinos in IceCube was performed. Such a signal could be an indication of Lorentz-violating physics. Neutrino oscillation models, derivable from extensions to the Standard Model, allow for neutrino oscillations that depend on the neutrino's direction of propagation. No such direction-dependent variation was found. A discrete Fourier transform method was used to constrain the Lorentz and CPT-violating coefficients in one of these models. Due to the unique high energy reach of IceCube, it was possible to improve constraints on certain Lorentz-violating oscillations by three orders of magnitude with respect to limits set by oth…
Analysis of the 4-year IceCube high-energy starting events
2016
After four years of data taking, the IceCube neutrino telescope has detected 54 high-energy starting events (HESE, or contained-vertex events) with deposited energies above 20TeV. They represent the first ever detection of high-energy extraterrestrial neutrinos and therefore, the first step in neutrino astronomy. In order to study the energy, flavor and isotropy of the astrophysical neutrino flux arriving at Earth, we perform different analyses of two different deposited energy intervals, [10 TeV $-$ 10 PeV] and [60 TeV $-$ 10 PeV]. We first consider an isotropic unbroken power-law spectrum and constrain its shape, normalization and flavor composition. Our results are in agreement with the …
Implications of new generations on neutrino masses
2011
We explore the possible implications that new families, that are being searched for at the LHC, would have on neutrino masses. In particular, we have explored the possibility that the smallness of the observed neutrino masses is naturally understood in a modified version of the Standard Model (SM) with complete extra generations of fermions, i.e., that have right-handed neutrinos, in which neutrino masses are generated at two loops. With one extra family it is not possible to fit the observed spectrum of masses and mixings. However, the radiative mass generated provides an important constraint in these kind of models, so the neutrino masses do not exceed their cosmological bound. Within the…
Results and status from the HARP and MIPP hadron production experiments
2008
Recent results and status from the HARP and MIPP hadron production experiments are reviewed. After a brief description of the experimental setups and the large amounts of data collected with those, we emphasize the relevance of precision hadron production measurements for neutrino physics. Three types of neutrino sources are discussed: conventional accelerator-based neutrino beams, advanced neutrino sources, and atmospheric neutrinos. We conclude by discussing prospects from additional hadron production measurements to be expected in the near future.
Standard and non-standard analysis of solar and reactor neutrino data
2010
We present an updated analysis of solar and reactor neutrino data in the standard framework of neutrino oscillations. We also consider the presence of non-standard neutrino interactions with matter and perform an alternative analysis of neutrino d ata studying the non-standard effects both on the neutrino detection and propagation through matter.
MiniBooNE: first results on the muon-to-electron neutrino oscillation search
2008
MiniBooNE's first results on a search for an electron neutrino excess in a muon neutrino beam are presented, together with an analysis of the data within a two neutrino Vμ → Ve appearance-only oscillation context. MiniBooNE finds excellent agreement between data and Standard Model predictions in the oscillation analysis energy region. If neutrino and antineutrino oscillations are the same, MiniBooNE excludes at ~98% confidence level the two neutrino Vμ → Ve appearance-only oscillation interpretation of the LSND anomaly. MiniBooNE also finds a discrepancy at energies below the oscillation analysis range, which is currently not understood and under investigation.
Probingθ13with global neutrino data analysis
2010
We discuss the results of an updated global analysis of neutrino oscillation data, focusing on the determination of θ13, the smallest and unknown leptonic mixing angle. We discuss three independent and converging hints of θ13 > 0: a first one coming from atmospheric neutrino data; a second one from the combination of solar and long-baseline reactor (KamLAND) neutrino data; and a third one from the latest MINOS measurements in the appearance (νμ → νe) channel. Their combination provides an indication for θ13 > 0 at the 2σ (95% C.L.) level.
Search for sterile neutrinos at radioactive ion beam facilities
2013
We propose applications of Radioactive Ion Beam facilities to investigate physics beyond the Standard Model. In particular, we focus upon the search for sterile neutrinos by means of a low energy beta-beam with a Lorentz boost factor of 1. In the considered setup, collected 8Li radioactive ions are sent inside a 4? detector filled with a liquid scintillator, with inverse-beta decay as neutrino detection channel. We provide exclusion curves for the sterile neutrino mixing parameters, based upon the 3+1 formalism, depending upon the achievable ion intensity. The proposed experiment represents a possible alternative to clarify the current anomalies observed in neutrino experiments.
Neutrino masses: evidences and implications
2014
I give an overview of the evidences for neutrino masses and mixing, the associated neutrino mass generation schemes, as well as the resulting implications in particle physics experiments and cosmology.