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43
FNAL-PUB-08-215-A-T Gravitational Wave Bursts from Cosmic Superstring Reconnections
, 901
"... We compute the gravitational waveform produced by cosmic superstring reconnections. This is done by first constructing the superstring reconnection trajectory, which closely resembles that of classical, instantaneous reconnection but with the singularities smoothed out due to the string path integra ..."
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We compute the gravitational waveform produced by cosmic superstring reconnections. This is done by first constructing the superstring reconnection trajectory, which closely resembles that of classical, instantaneous reconnection but with the singularities smoothed out due to the string path integral. We then evaluate the graviton vertex operator in this background to obtain the burst amplitude. The result is compared to the detection threshold for current and future gravitational wave detectors, finding that neither bursts nor the stochastic background would be detectable by Advanced LIGO. This disappointing but anticipated conclusion holds even for the most optimistic values of the reconnection probability and loop sizes. 1 1
Top-Down Models and Extremely High Energy Cosmic Rays
, 1999
"... We developed numerical code for calculation of the extragalactic component of the spectra of leptons, nucleons and γ-rays resulting from “top-down ” (nonacceleration) models for the case of uniform and isotropic source distribution. We explored two different classes of “top-down ” scenarios: the wid ..."
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We developed numerical code for calculation of the extragalactic component of the spectra of leptons, nucleons and γ-rays resulting from “top-down ” (nonacceleration) models for the case of uniform and isotropic source distribution. We explored two different classes of “top-down ” scenarios: the wide earlier investigated class of X particles coming from collapse and/or annihilation of cosmic topological defects (such as cosmic strings, monopoles, etc.) and the models of super-heavy long-living X particles with lifetime of the order or much greater than the current Universe age. I.
PHYSICS OF EXTREMELY HIGH ENERGY COSMIC RAYS
, 2000
"... Over the last third of the century, a few tens of events, detected by ground-based cosmic ray detectors, have opened a new window in the field of high-energy astrophysics. These events have macroscopic energies- exceeding 5 × 10 19 eV-, unobserved sources- if supposed to be in our vicinity-, an unkn ..."
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Over the last third of the century, a few tens of events, detected by ground-based cosmic ray detectors, have opened a new window in the field of high-energy astrophysics. These events have macroscopic energies- exceeding 5 × 10 19 eV-, unobserved sources- if supposed to be in our vicinity-, an unknown chemical composition and a production and transport mechanism yet to be explained. With a flux as low as one particle per century per square kilometer, only dedicated detectors with huge apertures can bring in the high-quality and statistically significant data needed to answer those questions. In this article, we review the present status of the field both from an experimental and theoretical point of view. Special attention is given to the next generation of detectors devoted to the thorough exploration of the highest energy ranges. 1.
1Artificial Neural Network as a FPGA Trigger for a Detection of Very Inclined Air Showers
"... Abstract—The observation of ultra-high energy neutrinos (UHEνs) has become a priority in experimental astroparticle physics. Neutrinos can interact in the atmosphere (downward-going ν) or in the Earth crust (Earth-skimming ν), producing air showers that can be observed with arrays of detectors at th ..."
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Abstract—The observation of ultra-high energy neutrinos (UHEνs) has become a priority in experimental astroparticle physics. Neutrinos can interact in the atmosphere (downward-going ν) or in the Earth crust (Earth-skimming ν), producing air showers that can be observed with arrays of detectors at the ground. The surface detector array of the Pierre Auger Ob-servatory can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). Up to now, the Pierre Auger Observatory did not find any candidate for a neutrino event. This imposes competitive limits to the diffuse flux of UHEνs. A very low rate of events potentially generated by neutrinos is a significant challenge for a detection technique and requires both sophisticated algorithms and high-resolution hardware. We
Anomaly mediation and cosmology
, 2011
"... Abstract: We consider an extension of the MSSM wherein anomaly mediation is the source of supersymmetry-breaking, and the tachyonic slepton problem is solved by a gauged U(1) symmetry, which is broken at high energies in a manner preserving supersymmetry, thereby also facilitating the see-saw mechan ..."
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Abstract: We consider an extension of the MSSM wherein anomaly mediation is the source of supersymmetry-breaking, and the tachyonic slepton problem is solved by a gauged U(1) symmetry, which is broken at high energies in a manner preserving supersymmetry, thereby also facilitating the see-saw mechanism for neutrino masses and a natural source for the Higgs µ-term. We show that these favourable outcomes can occur both in the presence and the absence of a large Fayet-Iliopoulos (FI) D-term associated with the new U(1). We explore the cosmological consequences of the model, showing that it naturally produces a period of hybrid inflation, terminating in the production of cosmic strings. In spite of the presence of a U(1) (even with an FI term), inflation is effected by the F-term, with a D-flat tree potential (the FI term, if present, being cancelled by non-zero squark and slepton fields). Calculating the 1-loop corrections to the inflaton potential, we estimate the constraints on the parameters of the model from Cosmic Microwave Background data. We will see that a consequence of these constraints is that the Higgs µ-term necessarily small. We briefly discuss the mechanisms for baryogenesis via conventional leptogenesis, the out-of-equilibrium production of neutrinos from the cosmic strings, or the Affleck-Dine mechanism. Cosmic string decays also boost the relic density of dark matter above the low value normally obtained in AMSB scenarios.
unknown title
, 2007
"... The detection of megaelectron volt neutrinos from the Sun enabled direct observations of nuclear reactions in the core of the Sun, as well as studies of fundamental neutrino properties (Bahcall 2005). Existing megaelectron volt neutrino ‘telescopes ’ are also capable of detecting neutrinos from supe ..."
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The detection of megaelectron volt neutrinos from the Sun enabled direct observations of nuclear reactions in the core of the Sun, as well as studies of fundamental neutrino properties (Bahcall 2005). Existing megaelectron volt neutrino ‘telescopes ’ are also capable of detecting neutrinos from supernova
DESY-06-088 Probing Neutrino Dark Energy with Extremely High-Energy Cosmic Neutrinos
, 2006
"... Recently, a new non-Standard Model neutrino interaction mediated by a light scalar field was proposed, which renders the big-bang relic neutrinos of the cosmic neutrino background a natural dark energy candidate, the so-called Neutrino Dark Energy. As a further consequence of this interaction, the n ..."
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Recently, a new non-Standard Model neutrino interaction mediated by a light scalar field was proposed, which renders the big-bang relic neutrinos of the cosmic neutrino background a natural dark energy candidate, the so-called Neutrino Dark Energy. As a further consequence of this interaction, the neutrino masses become functions of the neutrino energy densities and are thus promoted to dynamical, time/redshift dependent quantities. Such a possible neutrino mass variation introduces a redshift dependence into the resonance energies associated with the annihilation of extremely high-energy cosmic neutrinos on relic anti-neutrinos and vice versa into Z-bosons. In general, this annihilation process is expected to lead to sizeable absorption dips in the spectra to be observed on earth by neutrino observatories operating in the relevant energy region above 10 13 GeV. In our analysis, we contrast the characteristic absorption features produced by constant and varying neutrino masses, including all thermal background effects caused by the relic neutrino motion. We firstly consider neutrinos from astrophysical sources and secondly neutrinos originating from the decomposition of topological defects using the appropriate fragmentation functions. On the one hand, independent of the nature of neutrino masses, our results illustrate the discovery potential for the cosmic neutrino background by means of relic neutrino absorption spectroscopy. On the other hand, they allow to estimate the prospects for testing its possible interpretation as source of Neutrino Dark Energy within the next decade by the neutrino observatories ANITA and LOFAR. Probing Neutrino Dark Energy with Extremely High-Energy Cosmic Neutrinos 2 1.
Generation of 10 15 − 10 17 eV photons by UHE CR in the Galactic magnetic filed.
, 1999
"... We show that the deep expected in the diffuse photon spectrum above the threshold of e + e −-pair production, i.e., at energies 10 15 − 10 17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magne ..."
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We show that the deep expected in the diffuse photon spectrum above the threshold of e + e −-pair production, i.e., at energies 10 15 − 10 17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magnetic filed. The mechanism we propose requires small (< 10 −11 G) extragalactic magnetic fields and large fraction of photons in the UHE CR. For a typical photon flux expected in top-down scenarios of UHE CR, the predicted flux in the region of the deep is close to the existing experimental limit. The sensitivity of our mechanism to the extragalactic magnetic field may be used to improve existing bounds on the latter by two orders of magnitude. 1
Instituto de Física Corpuscular (CSIC-Universitat de València), Ed. Institutos de
, 2007
"... Abstract. We perform a study of the ultra high energy neutrino detection performances of a km 3 Neutrino Telescope sitting at the three proposed sites for ANTARES, NEMO and NESTOR in the Mediterranean sea. We focus on the effect of the underwater surface profile on the total amount of yearly expecte ..."
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Abstract. We perform a study of the ultra high energy neutrino detection performances of a km 3 Neutrino Telescope sitting at the three proposed sites for ANTARES, NEMO and NESTOR in the Mediterranean sea. We focus on the effect of the underwater surface profile on the total amount of yearly expected τ and µ crossing the fiducial volume in the limit of full detection efficiency and energy resolution. We also emphasize the possible enhancement of matter effect by a suitable choice of the geometry of the Telescope. PACS numbers: 95.85.Ry, 95.55.Vj, 13.15.+gUltra High Energy Neutrinos in the Mediterranean 2 1.
