940 Matching Results

Search Results

Advanced search parameters have been applied.

Field Theory On the World Sheet: Mean Field Expansion And Cutoff Dependence

Description: Continuing earlier work, we apply the mean field method to the world sheet representation of a simple field theory. In particular, we study the higher order terms in the mean field expansion, and show that their cutoff dependence can be absorbed into a running coupling constant. The coupling constant runs towards zero in the infrared, and the model tends towards a free string. One cannot fully reach this limit because of infrared problems, however, one can still apply the mean field method to the high energy limit (high mass states) of the string.
Date: January 10, 2007
Creator: Bardakci, Korkut
Partner: UNT Libraries Government Documents Department

CARBON-13 NMR STUDIES OF LIQUID CRYSTALS

Description: High resolution, proton decoupled {sup 13}C nmr are observed for a series of neat nematic liquid crystals, the p-alkoxyazoxybenzenes, and a smectic-A liquid crystal, diethylazoxydibenzoate in a magnetic field of 23 kG. The (uniaxial) order parameters S = <P{sub 2}(cos{theta})> are found to be about 0.4 and 0.9 for the nematic and smectic-A phase respectively at the clearing points. The order parameter increases with decreasing temperature in the nematic phase but is constant, or nearly so, with temperature in the smectic-A phase. In the nematic series studied, the ordering exhibits an even-odd alternation along the series and qualitative agreement with a recent theory due to Marcelja is found. In both phases, the spectra show that the molecule rotates rapidly about its long axis. Tentative conclusions about molecular conformational motion and {sup 14}N spin relaxation are presented for both nematic and smectic-A phases. In the smectic-A phase, the sample is rotated about an axis perpendicular to H{sub 0} and the resulting spectra are discussed. The theory of observed chemical shifts in liquid crystals is treated in an appendix. Equations are derived which relate the nmr spectra of liquid-crystals to the order parameters. A model for the smectic-C phase due to Luz and Meiboom and Doane is described and lineshapes are determined on the basis of this model for special cases. Experiments on smectic-C liquid crystals are currently underway for comparison with the theory. Also treated in an appendix is the dependence of the order parameters on the molecular potential which give rise to the various degrees of order in the different liquid crystalline phases. To a good approximation the functional dependence of the order parameters on the molecular potential is shown to be a simple one in the limit of small tilt angle in the smectic-C phase.
Date: June 1, 1975
Creator: Allison, Stuart
Partner: UNT Libraries Government Documents Department

REVIEW OF PARTICLE PHYSICS

Description: This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, V{sub cb} & V{sub ub}, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.
Date: July 16, 2012
Creator: Beringer, Juerg
Partner: UNT Libraries Government Documents Department

Searle's"Dualism Revisited"

Description: A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.
Date: November 20, 2008
Creator: P., Henry
Partner: UNT Libraries Government Documents Department

Quantum Locality?

Description: Robert Griffiths has recently addressed, within the framework of a ‘consistent quantum theory’ (CQT) that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues, on the basis of his examination of certain arguments that claim to demonstrate the existence of such nonlocal influences, that such influences do not exist. However, his examination was restricted mainly to hidden-variable-based arguments that include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by attributing to the system properties alien to that system. Hence Griffiths’ rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his ‘consistent quantum theory’ shows that the cited proof is valid within that restrictive framework. This necessary existence, within the ‘consistent’ framework, of long range essentially instantaneous influences refutes the claim made by Griffiths that his ‘consistent’ framework is superior to the orthodox quantum theory of von Neumann because it does not entail instantaneous influences. An added section responds to Griffiths’ reply, which cites a litany of ambiguities that seem to restrict, devastatingly, the scope of his CQT formalism, apparently to buttress his claim that my use of that formalism to validate the nonlocality theorem is flawed. But the vagaries that he cites do not upset the proof in question. ...
Date: November 10, 2011
Creator: Stapp, Henry
Partner: UNT Libraries Government Documents Department

Progress Report No. 69. Dec. 15, 1948 to Jan. 15, 1949

Description: This is the progress report for the University of California, Radiation Laboratory for December 15, 1948-January 15, 1949. It discusses the following: (1) Bevatron; (2) 184-inch Cyclotron Program; (3) 60-inch Cyclotron Program; (4) Synchrotron Operation; (5) Linear Accelerator and Van de Graaff Operation; (6) Experimental Physics; (7) Theoretical Physics, (8) Isotope Separation; (9) Chemistry Departments; (10) Medical Physics; and (11) Health Physics and Chemistry.
Date: January 30, 1949
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department

OVERVIEW OF HEAVY ION FUSION PROGRAM IN U.S.A

Description: The current national program comprises the following major activities: (1) preliminary design, systems studies, and cost estimates for a reference 'pilot-plant' driver [Beam energy = 1 MJ; Beam power on target = 100 TW; specific energy deposition {ge} 20 MJ/gm]; (2) consequent upon this reference design, definition of an intermediate Heavy Ion Demonstration Experiment (HIDE) to test the accelerator technology and to begin to probe the scaling behavior of the heavy-ion target behavior, current thinking suggests that the beam energy should be about 100 kJ, or roughly one-tenth that of the reference design, in present DOE plans, HIDE is assumed to be operating in FY1985 or FY1986. (3) Design of targets optimized for heavy-ion driver; relaxation of the high beam-power requirements would allow accelerator designs to produce lower kinetic energy for the ion and permit a longer final pulse duration, thus easing a difficult demand on present-day accelerator behavior; (4) development of a clear understanding of the design implications of the beam space-charge limits, both longitudinal and transverse, several of the accelerator system design parameters, e.g apertures, number of final beams, size of final focusing magnets, are sensitive to assumptions about the six-dimensional phase-space density and volume of the beam. Creatoni and preservation of a suitable density is intimately related to various of the space-charge limits which in turn have an impact on the cost of the driver; (5) demonstration of suitable heavy-ion sources and acceleration of the beams to modest energies as a bench-test of a pre-accelerator; and (6) definition of the final focusing procedures including the final beam propagation and stability in a reactor vessel environment.
Date: February 1, 1978
Creator: Keefe, Denis
Partner: UNT Libraries Government Documents Department

NUCLEAR HOLE STATES AS A PROBE OF THE NUCLEAR MANY BODY SYSTEM

Description: Nuclear hole states studied in proton and neutron pick-up reactions on light and heavy target nuclei exhibit -- for deeply-bound shell model orbits -- properties, which are strongly affected by target nucleus collectivities. Quasiparticle-like holes in nuclei are formed showing features very similar to those of other highly excited modes e.g. giant quadrupole resonances. The similarity between these two complicated modes of excitation in light and heavy nuclei asks for a detailed theoretical interpretation. Both modes are built up by a bulk of levels with fixed spin and parity in the continuum region of nuclei. Deeply bound hole states may, like giant multipole resonances, be interpreted as collective phenomena and, therefore, can represent a new tool for investigating the nuclear many body system. {gamma}-decay measurements of these complicated modes, or nuclear photoeffect measurements of quasiholes, would provide the most direct access to their collective structure. However, such experiments are difficult to perform. On the other hand, light Particle decay studies for the systems discussed here, will surely help to clarify their common microscopic features.
Date: August 1, 1978
Creator: Doll, P.
Partner: UNT Libraries Government Documents Department

Monthly Progress Report No. 61 for May, 1948

Description: This is the University of California, Radiation Laboratory monthly progress report for May 1948. It discusses the following: (1) 184-inch Cyclotron Program; (2) 60-inch Cyclotron Program; (3) Synchrotron Program; (4) Linear Accelerator Program; (5) Experimental Physics; (6) Theoretical Physics, (7) Isotope Separation Program; (8) Chemistry Departments; (9) Medical Physics; and (10) Health Physics and Chemistry.
Date: May 31, 1948
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department

The Origin of Apollo Objects

Description: The source of the Earth-orbit-crossing asteroids has been much debated. (This class of asteroidal bodies includes the Apollo, Aten, and some Amor objects, each with its own orbital characteristics; we shall use the term Apollo objects to mean all Earth-crossers.) It is difficult to find a mechanism which would create new Apollo objects at a sufficient rate to balance the loss due to collision with planets and ejection from the solar system, and thus explain the estimated steady-state number. A likely source is the main asteroid belt, since it has similar photometric characteristics. There are gaps in the main belt which correspond to orbits resonant with the orbits of Jupiter and Saturn, and it has been shown that the resonances can perturb a body into an Earth-crossing orbit. Apollo objects could thus be generated when random collisions between asteroids in the main belt sent fragments into these resonant orbits. Calculations of the creation rate from these random collisions, however, yielcl numbers too low by a factor of four. This rate could be significantly lower given the uncertainty in the efficiency of the resonance mechanism. As an alternative, it was suggested that the evaporation of a comet's volatile mantle as it passes near the sun could provide enough non-gravitational force to move the comet into an orbit with aphelion inside of Jupiter's orbit, and thus safe from ejection from the solar system. The probability of such an event occurring is unknown, although the recent discovery of the 'asteroid' 1983 TB, with an orbit matching that of the Geminid meteor shower, suggests that such a mechanism has occurred at least once. New evidence from paleontology and geophysics, however, suggests a better solution to the problem of the source of the Apollos. M. Davis, P. Hut, and R. A. Muller recently proposed that ...
Date: March 29, 1984
Creator: Perlmutter, Saul
Partner: UNT Libraries Government Documents Department

Progress Report No. 63 June 15-July 15, 1948

Description: This is the University of California, Radiation Laboratory progress report for June 15-July 15, 1948. It discusses the following: (1) 184-inch Cyclotron Program; (2) 60-inch Cyclotron Program; (3) Synchrotron Program; (4) Linear Accelerator Program; (5) Experimental Physics; (6) Theoretical Physics, (7) Isotope Separation Program; (8) Chemistry Departments; (9) Medical Physics; and (10) Health Physics and Chemistry.
Date: July 30, 1948
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department

Nucleon decay in GUT and nonGUT SUSY models

Description: I first emphasize the importance of searching for nucleon decay in the context of supersymmetric models. The status of minimal SUSY SU(5) model is reviewed, which can be definitively ruled out by a combination of superKamiokande andLEP-2 experiments. Non-minimal models may provide some suppression in the nucleon decay rates, but there is still a good chance for superKamiokande. I point out that the operators suppressed even by the Planck-scale are too large. We need a suppression mechanism for the operators at the level of 10-7, and the mechanism, I argue, may well be a flavor symmetry. A particular example predicts p --> K0e+ to be the dominant mode which does not arise in GUT models.
Date: June 30, 1996
Creator: Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Harmonic resolution as a holographic quantum number

Description: The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.
Date: January 31, 2004
Creator: Bousso, Raphael
Partner: UNT Libraries Government Documents Department

Constraints and Casimirs for Super Poincare and Supertranslation Algebras in various dimensions

Description: We describe, for arbitrary dimensions the construction of a covariant and supersymmetric constraint for the massless Super Poincare algebra and we show that the constraint fixes uniquely the representation of the algebra. For the case of finite mass and in the absence of central charges we discuss a similar construction, which generalizes to arbitrary dimensions the concept of the superspin Casimir. Finally we discuss briefly the modifications introduced by central charges, both scalar and tensorial.
Date: November 3, 2004
Creator: Zumino, Bruno
Partner: UNT Libraries Government Documents Department

Cosmology and the S-matrix

Description: We study conditions for the existence of asymptotic observables in cosmology. With the exception of de Sitter space, the thermal properties of accelerating universes permit arbitrarily long observations, and guarantee the production of accessible states of arbitrarily large entropy. This suggests that some asymptotic observables may exist, despite the presence of an event horizon. Comparison with decelerating universes shows surprising similarities: Neither type suffers from the limitations encountered in de Sitter space, such as thermalization and boundedness of entropy. However, we argue that no realistic cosmology permits the global observations associated with an S-matrix.
Date: January 25, 2005
Creator: Bousso, Raphael
Partner: UNT Libraries Government Documents Department

Electronic Circuits Lectures

Description: The two-electrode vacuum tube, or diode, consists of an electron-emitting cathode surrounded by a positive anode (plate). A plot of plate current (i{sub b}) vs plate voltage (e{sub b}) is shown. At low anode voltages, the anode current is limited by the repelling effect that the negative electrons already in the space have on the electrons just being emitted (space-charge effect). When a full space charge is present, the plate current depends upon the plate voltage according to Childs law: i{sub b} {approx} e{sub b}{sup 3/2}. Increasing the plate voltage eventually results in an electron flow equal to total cathode emission, after which further increases in anode voltage will produce practically no additional current (voltage saturation). However, for high field stresses, additional electrons are pulled out of the cathode (field emission), increasing the current even further.
Date: December 1, 1947
Creator: Mozley, Robert
Partner: UNT Libraries Government Documents Department

Z' Bosons, the NuTeV Anomaly, and the Higgs Boson Mass

Description: Fits to the precision electroweak data that include the NuTeV measurement are considered in family universal, anomaly free U(1) extensions of the Standard Model. In data sets from which the hadronic asymmetries are excluded, some of the Z{prime} models can double the predicted value of the Higgs boson mass, from {approx} 60 to {approx} 120 GeV, removing the tension with the LEP II lower bound, while also modestly improving the {chi}{sup 2} confidence level. The effect of the Z{prime} models on both m{sub H} and the {chi}{sup 2} confidence level is increased when the NuTeV measurement is included in the fit. Both the original NuTeV data and a revised estimate by the PDG are considered.
Date: March 3, 2009
Creator: Chanowitz, Michael S
Partner: UNT Libraries Government Documents Department

Flat space physics from holography

Description: We point out that aspects of quantum mechanics can be derived from the holographic principle, using only a perturbative limit of classical general relativity. In flat space, the covariant entropy bound reduces to the Bekenstein bound. The latter does not contain Newton's constant and cannot operate via gravitational backreaction. Instead, it is protected by--and in this sense, predicts--the Heisenberg uncertainty principle.
Date: February 6, 2004
Creator: Bousso, Raphael
Partner: UNT Libraries Government Documents Department

Duals for SU(N) SUSY Gauge Theories with an Antisymmetric Tensor: Five Easy Flavors

Description: I consider N = 1 supersymmetric SU(N{sub c}) gauge theories with matter fields consisting of one antisymmetric representation, five flavors, and enough antifundamental representations to cancel the gauge anomaly. Previous analyses are extended to the case of even N{sub c} with no superpotential. Using holomorphy I show that the theory has an interacting infrared fixed point for sufficiently large N{sub c}. These theories are interesting due to the fact that in going from five to four flavors the theory goes from a non-trivial infrared fixed point to confinement, in contradistinction to SUSY QCD, but in analogy to the behavior expected in non-SUSY QCD.
Date: December 16, 1997
Creator: Terning, John
Partner: UNT Libraries Government Documents Department

The Production of Thin Be Foils

Description: A procedure for making Be foils between 10{sup -5} cm. and 10{sup -3} cm. thick, and with diameters up to an inch and a half is described, and methods of mounting these foils are indicated.The problem of making thin Be foils was presented in connection with focusing the proton beam in the Berkeley Linear Accelerator, and although the foils are not now used in the accelerator, they have proved to be quite useful as thin targets, target supports, thin windows, etc. The Be was evaporated in vacuum and deposited on a metal collector plate. The problems encountered were: (1) obtaining reproducible quantities of evaporated Be; (2) stripping of Be from the collector plates; (3) preventing curl of the foils when they were stripped; and (4) mounting the foils.
Date: March 18, 1948
Creator: Bradner, Hugh
Partner: UNT Libraries Government Documents Department

Progress Report for 1947

Description: The year 1947 has witnessed the dawn of a new era of atomic science, a flowering of fundamental knowledge of the nature of matter which appears to be unsurpassed even by that period of the 1930's which led to the age of plutonium. A great new cyclotron, an atom-smasher ten times more powerful than the one which brought plutonium into the world, has carried mankind over a new horizon of sub-atomic space. It has brought scientists at last to grips with the infinitely small and rapid forces, until now beyond reach, which operate within the incredibly tiny distances of nuclear space. On the new energy frontier created by the giant machine, now laws govern nuclear reactions. methods are at hand, heretofore unavailable, which permit the measurement and determination of the nature of sub-atomic forces. Under ultra-high energy bombardment, the nucleus presents a different appearance from the nucleus of Bohr and Rutherford, the nucleus of atomic energy fission. The new exploration of the atom has been sponsored by the Atomic Energy Commission with the giant, new 4000-ton cyclotron in the Radiation Laboratory of the University of California. This is the thirdmajor machine built by the Director of the Laboratory and inventor of the cyclotron, Professor Ernest O. Lawrence. Whether the new knowledge will be of immediate practical consequence cannot now be predicted. Nor could Professor Lawrence predict, when in 1934 he established a new atomic energy range for that day with his first cyclotron, that the fundamental knowledge he pursued would be climaxed with the discovery of plutonium. What can be predicted is this: without the new basic knowledge, practical atomic developments of the future would be limited to the applicability of the fundamental information which made possible the initial release of atomic energy. In short, the nation's atomic potential has ...
Date: November 1, 1947
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department