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Minimum entropy production of neutrino radiation in the steady state

Description: A thermodynamical minimum principle valid for photon radiation is shown to hold for arbitrary geometries. It is successfully extended to neutrinos, in the zero mass and chemical potential case, following a parallel development of photon and neutrino statistics. This minimum principle stems more from that of Planck than that of classical Onsager-Prigogine irreversible thermodynamics. Its extension from bosons to fermions suggests that it may have a still wider validity. 14 refs.
Date: August 1, 1997
Creator: Essex, C. & Kennedy, D.C.
Partner: UNT Libraries Government Documents Department

Search for axion-like particles using a variable baseline photon regeneration technique

Description: We report the first results of the GammeV experiment, a search for milli-eV mass particles with axion-like couplings to two photons. The search is performed using a 'light shining through a wall' technique where incident photons oscillate into new weakly interacting particles that are able to pass through the wall and subsequently regenerate back into detectable photons. The oscillation baseline of the apparatus is variable, thus allowing probes of different values of particle mass. We find no excess of events above background and are able to constrain the two-photon couplings of possible new scalar (pseudoscalar) particles to be less than 3.1 x 10 {sup -7} GeV {sup -1} (3.5 x 10{sup -7} GeV{sup -1}) in the limit of massless particles.
Date: October 1, 2007
Creator: Chou, A. S.; Wester, William Carl, III; Baumbaugh, A.; Gustafson, D.; Irizarry-Valle, Y.; Mazur, P. O. et al.
Partner: UNT Libraries Government Documents Department

Realization of Center Symmetry in Two Adjoint Flavor Large-N Yang-Mills

Description: We report on the results of numerical simulations of SU(N) lattice Yang Mills with two flavors of (light) Wilson fermion in the adjoint representation. We analytically and numerically address the question of center symmetry realization on lattices with {Lambda} sites in each direction in the large-N limit. We show, by a weak coupling calculation that, for massless fermions, center symmetry realization is independent of {Lambda}, and is unbroken. Then, we extend our result by conducting simulations at non zero mass and finite gauge coupling. Our results indicate that center symmetry is intact for a range of fermion mass in the vicinity of the critical line on lattices of volume 2{sup 4}. This observation makes it possible to compute infinite volume physical observables using small volume simulations in the limit N {yields} {infinity}, with possible applications to the determination of the conformal window in gauge theories with adjoint fermions.
Date: August 26, 2010
Creator: Catterall, Simon; U., /Syracuse; Galvez, Richard; U., /Syracuse; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept.
Partner: UNT Libraries Government Documents Department

Neutrino oscillations in the early universe II

Description: We show that it is possible for neutrino oscillations to create a state of the universe in which the net lepton numbers are appreciable and different for each species at the time of nucleosynthesis. Under these conditions mixing induced by the oscillations can influence the abundances of the light elements.
Date: 1982
Creator: McKellar, B. H. J. & Granek, H.
Partner: UNT Libraries Government Documents Department

Rapid cooling and structure of neutron stars

Description: This report discusses the following topics on neutron stars: direct URCA neutrino emission; thermal evolution models; analytic model for diffusion through the crust; and core superfluidity. (LSP).
Date: January 1, 1992
Creator: Van Riper, K.A. (Los Alamos National Lab., NM (United States)) & Lattimer, J.M. (State Univ. of New York, Stony Brook, NY (United States). Dept. of Earth and Space Sciences)
Partner: UNT Libraries Government Documents Department

The Complete Four-Loop Four-Point Amplitude in N

Description: We present the complete four-loop four-point amplitude in N = 4 super-Yang-Mills theory, for a general gauge group and general D-dimensional covariant kinematics, and including all non-planar contributions. We use the method of maximal cuts - an efficient application of the unitarity method - to construct the result in terms of 50 four-loop integrals. We give graphical rules, valid in D-dimensions, for obtaining various non-planar contributions from previously-determined terms. We examine the ultraviolet behavior of the amplitude near D = 11/2. The non-planar terms are as well-behaved in the ultraviolet as the planar terms. However, in the color decomposition of the three- and four-loop amplitude for an SU(N{sub c}) gauge group, the coefficients of the double-trace terms are better behaved in the ultraviolet than are the single-trace terms. The results from this paper were an important step toward obtaining the corresponding amplitude in N = 8 supergravity, which confirmed the existence of cancellations beyond those needed for ultraviolet finiteness at four loops in four dimensions. Evaluation of the loop integrals near D = 4 would permit tests of recent conjectures and results concerning the infrared behavior of four-dimensional massless gauge theory.
Date: August 25, 2010
Creator: Bern, Z.; Carrasco, J.J.M.; /UCLA; Dixon, Lance J.; /CERN, /SLAC; Johansson, H. et al.
Partner: UNT Libraries Government Documents Department

Diagnostics of a high current capillary discharge

Description: We have demonstrated that thin (10 to 25 ..mu..m diameter) capillaries can be fabricated in suitably configured insulators for use in pulse power machines. Large currents can be used to heat these capillaries which produce photons with an energies greater than 1 keV.
Date: March 29, 1984
Creator: Kania, D. R. & Jones, L. A.
Partner: UNT Libraries Government Documents Department

Experiment to search for finite mass neutrinos at Los Alamos

Description: The strong current interest among physicists of the possibility of finite-mass neutrinos has resulted in several proposals at Los Alamos for experiments to detect nonzero neutrino masses. Three experiments now underway and three proposed experiments at LAMPF are discussed. 1 table.
Date: January 1, 1980
Creator: Bowles, T.
Partner: UNT Libraries Government Documents Department

Cherenkov Radiation from Jets in Heavy-ion Collisions

Description: The possibility of Cherenkov-like gluon bremsstrahlung in dense matter is studied. We point out that the occurrence of Cherenkov radiation in dense matter is sensitive to the presence of partonic bound states. This is illustrated by a calculation of the dispersion relation of a massless particle in a simple model in which it couples to two different massive resonance states. We further argue that detailed spectroscopy of jet correlations can directly probe the index of refraction of this matter, which in turn will provide information about the mass scale of these partonic bound states.
Date: July 26, 2005
Creator: Koch, Volker; Majumder, Abhijit & Wang, Xin-Nian
Partner: UNT Libraries Government Documents Department

Absence of Rapid Proton Decay and Origin of Low-Energy Particlesand Yukawa Couplings

Description: In string theory, massless particles often originate from a symmetry breaking of a large gauge symmetry G to its subgroup H. The absence of dimension-4 proton decay in supersymmetric theories suggests that ({bar D},L) are different from {bar H}({bar 5}) in their origins. In this article, we consider a possibility that they come from different irreducible components in g/h. Requiring that all the Yukawa coupling constants of quarks and leptons be generated from the super Yang-Mills interactions of G, we found in the context of Georgi-Glashow H = SU(5) unification that the minimal choice of G is E{sub 7} and E{sub 8} is the only alternative. This idea is systematically implemented in Heterotic String, M theory and F theory, confirming the absence of dimension 4 proton decay operators. Not only H = SU(5) but also G constrain operators of effective field theories, providing non-trivial information.
Date: January 1, 2006
Creator: Tatar, Radu & Watari, Taizan
Partner: UNT Libraries Government Documents Department

Neutrino interactions in matter

Description: If a fermion is travelling through a medium, it can have matter-induced magnetic and electric dipole moments. These contributions conserve chirality, and can be nonvanishing even for a Majorana neutrino. Several implications for neutrino physics are discussed.
Date: March 1, 1993
Creator: Pal, P. B.
Partner: UNT Libraries Government Documents Department

NK Muon Beam

Description: The NK Muon Beam will be a modified version of the existing NT beam line. The decision to employ a modified version of the NT beam line was made based on considerations of cost and availability of the beam line. Preliminary studies considered use of other beam lines, e.g., the NW beam line, and even of moving the bubble chamber with its superconducting coils but were rejected for reasons such as cost, personnel limitations, and potential conflicts with other users.
Date: September 28, 1988
Creator: Koizumi, G.
Partner: UNT Libraries Government Documents Department

Experiments performed at the Lawrence Berkeley Laboratory bearing relation to Bell's inequality. [Localized particle-like photon]

Description: A series of experiments performed regarding the Bell inequality are briefly described. The results indicate that the notion of localized particle-like photons is consistent with experiment, and that such entities evidently do not split, at least with regard to their detectability. (JFP)
Date: April 1, 1976
Creator: Clauser, J. F.
Partner: UNT Libraries Government Documents Department

B Flavour Tagging with Artificial Neural Networks for the CDF II Experiment

Description: One of the central questions arising from human curiosity has always been what matter is ultimately made of, with the idea of some kind of elementary building-block dating back to the ancient greek philosophers. Scientific activities of multiple generations have contributed to the current best knowledge about this question, the Standard Model of particle physics. According to it, the world around us is composed of a small number of stable elementary particles: Electrons and two different kinds of quarks, called up and down quarks. Quarks are never observed as free particles, but only as bound states of a quark-antiquark pair (mesons) or of three quarks (baryons), summarized as hadrons. Protons and Neutrons, the constituents forming the nuclei of all chemical elements, are baryons made of up and down quarks. The electron and the electron neutrino - a nearly massless particle without electric charge - belong to a group called leptons. These two quarks and two leptons represent the first generation of elementary particles. There are two other generations of particles, which seem to have similar properties as the first generation except for higher masses, so there are six quarks and six leptons altogether. They were around in large amounts shortly after the beginning of the universe, but today they are only produced in high energetic particle collisions. Properties of particles are described by quantum numbers, for example charge or spin. For every type of particle, a corresponding antiparticle exists with the sign of all charges swapped, but similar properties otherwise. The Standard Model is a very successful theory, describing the properties of all known particles and the interactions between them. Many of its aspects have been tested in various experiments at very high precision. Although none of these experimental tests has shown a significant deviation from the corresponding Standard Model ...
Date: January 1, 2010
Creator: Schmidt, Andreas
Partner: UNT Libraries Government Documents Department

Solar neutrinos with three flavor mixings

Description: The recent[sup 71]Ga solar neutrino observation is combined with the [sup 37]Cl and Kamiokande-II observations in an analysis for neutrino masses and mixings. The allowed parameter region is found for matter enhanced mixings among all three neutrino flavors. Distortions of the solar neutrino spectrum unique to three flavors are possible and may be observed in continuing and next generation experiments.
Date: January 1, 1992
Creator: Harley, D.; Pantaleone, J. (Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory) & Kuo, T.K. (Purdue Univ., Lafayette, IN (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Neutrino mixing in a grand unified theory

Description: Neutrino mixing in a grand unified theory in which the neutrino mass matrix is determined by the Gell-Mann-Ramond-Slansky mechanism was investigated. With an arbitrary real right-handed Majorana mass matrix which incorporates three neutrino mass scales, the effects of the up-quark mass matrix are found to be dominant and as a result no significant mixing of ..nu../sub e/ occurs, while ..nu../sub ..mu../ - ..nu../sub ..gamma../ mixing can be substantial.
Date: January 1, 1980
Creator: Milton, K. & Tanaka, K.
Partner: UNT Libraries Government Documents Department

Bounds on neutrino masses from particle physics and cosmology

Description: We study the constraints imposed on the masses of nu/sub e/, nu/sub ..mu../ and nu/sub tau/ on the basis of direct experimental bounds, cosmological bounds, theoretical calculations of neutrino decay rates, experimental bounds on related decays of charged leptons and the structure of neutrino mass matrices in the ''see-saw'' mechanism. We consider standard model amplitudes as well as contributions from all ''beyond standard'' models. Assuming a simple ''reasonable'' form of the see-saw mechanism, we derive the bounds: m(nu/sub tau/) less than or equal to 65 eV, m(nu/sub ..mu../) less than or equal to 4 eV, m(nu/sub e/) less than or equal to 0.02 eV, M(W/sub R/) greater than or equal to 50 PeV.
Date: March 1, 1987
Creator: Nir, Y.
Partner: UNT Libraries Government Documents Department

Neutrino mass

Description: Neutrinos play a dominant role in both particle physics, astrophysics, and cosmology. In the our present understanding of the strong, weak, and electromagnetic forces, the group structure of the Standard Model is SU(3)[sub C] [circle times] SU(2)[sub L] [circle times] U(I)[sub EM]. In the Weinberg-Salam-Glashow Standard Electroweak Model, left-handed neutrinos sit in a doublet, while right-handed neutrinos are in a singlet, and therefore do not interact with the other known particles. Also in this model, the neutrinos are intrinsically massless. However, while the W-S-G model provides an amazingly accurate picture of our present cold Universe, It has a number of deficits. The Standard Model does not explain the origin of the group structure, It does not reduce the number of coupling constants required, nor does it offer any prediction for the physical masses of the particles. Thus, it is generally assumed that the Standard Model is but a subset of some larger gauge theory. A wide variety of Grand Unified field Theories (GUTs), Super Symmetric Models (SUSY), and Superstring models have been proposed as the model for this larger structure. In general, these models predict nonzero neutrino masses and contain mechanisms that provide for lepton-number violation. Thus, a variety of new phenomena are predicted, including finite neutrino masses and the possibility that neutrinos can oscillate from one type to another. This report looks at the possibility of detecting neutrino vat mass.
Date: January 1, 1993
Creator: Bowles, T.J.
Partner: UNT Libraries Government Documents Department

A CW-pion focusing horn for low-energy muon neutrino beams

Description: Low-energy muon neutrino beams can be produced from pion decays in-flight at high-intensity accelerators, such as the Los Alamos Meson Physics Facility (LAMPF), providing a new tool to study the role of the weak interaction in nuclear and particle physics. Employing a pion focusing device can enhance the neutrino flux by large factors, and reduce backgrounds by sign-selection of the parent pions. However, LAMPF's long beam pulse and high repetition rate makes it impractical to use pulsed horns like those found at high-energy accelerators. In this paper we discuss a CW-pion focusing device that uses coils wound inside vanes mounted radially around the beam axis to provide an azimuthal field. From our studies with a prototype magnet, we have found the optimum field configuration needed to focus pions at LAMPF energies can be obtained by adjusting the radial density of turns in the coils. This optimum yields an eight-fold increase in neutrino flux above the muon threshold over the bare-target case. Our calculations also indicate a correlation between the arrival time of the neutrinos in the detector and their energy.
Date: January 1, 1988
Creator: Dombeck, T.; Koetke, D.D.; Koetke, D.S. & Fisk, R.
Partner: UNT Libraries Government Documents Department

A search for heavy neutrino decays in a neutrino beam

Description: Decay of heavy neutrinos ..nu../sub H/ ..-->.. ..nu..l..mu..e(l = e, ..mu..) has been searched for in the Brookhaven Alternting Gradient Synchrotron wide-band neutrino beam. Since no significant excess of such events was found, upper limits on the neutrino mixing matrix elements, absolute value of U/sub eH//sup 2/ and absolute value of U/sub ..mu..H//sup 2/ were obtained for the mass range of 180 to 500 MeV.
Date: January 1, 1987
Creator: Ahrens, L.A.; Aronson, S.H.; Gibbard, B.G.; Murtagh, M.J.; White, D.H.; Callas, J.L. et al.
Partner: UNT Libraries Government Documents Department