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Full-Text Articles in Physics

Weak Decays Of The H-Dibaryon, Jf Donoghue, E Golowich, Br Holstein Nov 1986

Weak Decays Of The H-Dibaryon, Jf Donoghue, E Golowich, Br Holstein

Barry R Holstein

We calculate decay rates and branching fractions for the postulated S=-2 H dibaryon, both for the expected ΔS=1 channels (nΛ,nΣ0,pΣ-) and for the possible ΔS=2 mode (nn). For ΔS=1 decays we find the S waves are dominated by ΔI=(3/2) transitions due to the Pauli principle, which forces the six-quark final state to be in a SU(3) 27-plet. If observed, this would be the first breakdown of the ΔI=1/2 rule. The lifetime is long, of order 10-8 sec, which should be considered in planning experiments. In the ΔS=2 case ...


Gravitational Coupling At Finite Temperature, Jf Donoghue, Br Holstein, Rw Robinett Aug 1986

Gravitational Coupling At Finite Temperature, Jf Donoghue, Br Holstein, Rw Robinett

Barry R Holstein

We discuss a thermodynamic identity which helps explain why ≠ at finite temperature. In addition we complete the discussion of the gravitational force by including the gravitational variation of the temperature. Gradients in the temperature induce extra forces not accounted for by the usual coupling to the energy-momentum tensor.


The Lifetime Of A Deeply Bound H Dibaryon And The Cygnus X-3 Events, John Donoghue, Eugene Golowich, Barry Holstein Jul 1986

The Lifetime Of A Deeply Bound H Dibaryon And The Cygnus X-3 Events, John Donoghue, Eugene Golowich, Barry Holstein

John Donoghue

The explanation of the Cygnus X-3 events which involves a strange-quark star emitting the doubly strange H dibaryon requires the H to have a lifetime of greater than ten years. We calculate the AS = 2 H ~ NN for an H bound below AN threshold, and find ~n -< 6 days. 


Rigid Backbone: A New Geometry For Percolation, Anthony Roy Day, R. R. Tremblay, A.-M. S. Tremblay Jun 1986

Rigid Backbone: A New Geometry For Percolation, Anthony Roy Day, R. R. Tremblay, A.-M. S. Tremblay

Anthony Roy Day

It is shown that the diluted two-dimensional central-force problem belongs to a new class of percolation problems. Geometric properties such as the fractal dimension of the backbone, the correlation-length exponent, and the connectivity are completely different from those of previously studied percolation problems. Explicit calculations of the backbone and the construction of an algorithm which identifies the infinite rigid cluster clearly demonstrate the absence of singly connected bonds, the overwhelming importance of loops, and the long-range nature of the rigidity.


G. N. Lewis' Atom And Quantum Monte Carlo Studies Of Liquids, Randall W. Hall, Peter G. Wolynes May 1986

G. N. Lewis' Atom And Quantum Monte Carlo Studies Of Liquids, Randall W. Hall, Peter G. Wolynes

Randall W. Hall

Liquids that involve changes in electronic structure are difficult to simulate using pairwise additive forces. In this paper we use a semiempirical model of the internal structure of atoms in order to simulate simultaneously electronic and nuclear dynamics of fluids. The proposed excitonic phase of mercury is critically examined with these models.


Auger Analysis Of Si–H Bonding And Hydrogen Concentration In Hydrogenated Amorphous Silicon, Nancy Burnham, Aj Nelson, Ab Schwartzlander, Se Asher, Ll Kazmerski Apr 1986

Auger Analysis Of Si–H Bonding And Hydrogen Concentration In Hydrogenated Amorphous Silicon, Nancy Burnham, Aj Nelson, Ab Schwartzlander, Se Asher, Ll Kazmerski

Nancy A. Burnham

Auger electron spectroscopy line‐shape analysis of the Si‐L 2 3 V V peak has been performed on hydrogenated amorphous silicon (a‐Si:H). Both a‐Si:H produced by hydrogen implantation of siliconsingle crystals (for analytical standards) and thin films (fabricated for solar cell applications) were examined in these studies. Hydrogen concentrations were confirmed by secondary ion mass spectrometry, and samples having hydrogen content over the range 101 6–102 2 cm− 3 were evaluated. Correlations between the area under the deconvoluted L 2 3 V V transition peak and the known hydrogen content have resulted in a ...


Scanning Auger Microprobe Studies Of Ball Cratered Cds/Cuinse2 Solar Cells, Nancy Burnham, Ll Levenson, Rj Matson, R Noufi, Ll Kazmerski Apr 1986

Scanning Auger Microprobe Studies Of Ball Cratered Cds/Cuinse2 Solar Cells, Nancy Burnham, Ll Levenson, Rj Matson, R Noufi, Ll Kazmerski

Nancy A. Burnham

CdS/CuInSe2solar cell films are typically several micrometers thick. Composition profiles of these films are usually carried out on fracture cross sections by scanning Auger microscopy or by recording Auger spectra during ion milling. For fracture cross sections, the depth resolution depends on the electron beam diameter and the roughness of the fracture surface. Ion milling is time consuming, and artifacts are caused by ion beam faceting. Ball cratering requires only a fraction of an hour and provides significant magnification of the film cross section. There is sufficient contrast, both in optical and electron microscopy, to distinguish between CdS and ...


Chiral Symmetry, Nonleptonic Hyperon Decay, And The Feinberg-Kabir-Weinberg Theorem, Jf Donoghue, Br Holstein Apr 1986

Chiral Symmetry, Nonleptonic Hyperon Decay, And The Feinberg-Kabir-Weinberg Theorem, Jf Donoghue, Br Holstein

Barry R Holstein

We demonstrate that additional (kaon-pole) diagrams must be appended to the traditional commutator-plus-baryon-pole approach to nonleptonic hyperon decay. The modified analysis satisfied the constraints of the Feinberg-Kabir-Weinberg theorem. The new terms are not numerically significant in the case of the usual current-current Hamiltonian, in the continuum limit, but can be important for work using lattice techniques or for other Hamiltonians.


The Rigid Backbone: A New Geometry For Percolation., Anthony Day, R. Tremblay, A.-M. Tremblay Dec 1985

The Rigid Backbone: A New Geometry For Percolation., Anthony Day, R. Tremblay, A.-M. Tremblay

Anthony Roy Day

It is shown that the diluted two-dimensional central-force problem belongs to a new class of percolation problems. Geometric properties such as the fractal dimension of the backbone, the correlation-length exponent, and the connectivity are completely different from those of previously studied percolation problems. Explicit calculations of the backbone and the construction of an algorithm which identifies the infinite rigid cluster clearly demonstrate the absence of singly connected bonds, the overwhelming importance of loops, and the long-range nature of the rigidity.


Electromagnetic And Isopin Breaking Effects Decrease Epsilon'/Epsilon, Jf Donoghue, E Golowich, Br Holstein, J Trampetic Dec 1985

Electromagnetic And Isopin Breaking Effects Decrease Epsilon'/Epsilon, Jf Donoghue, E Golowich, Br Holstein, J Trampetic

Barry R Holstein

No abstract provided.


Chiral Perturbation-Theory Corrections To Kl-]-Gamma-Gamma, Jf Donoghue, Br Holstein, Ycr Lin Dec 1985

Chiral Perturbation-Theory Corrections To Kl-]-Gamma-Gamma, Jf Donoghue, Br Holstein, Ycr Lin

Barry R Holstein

No abstract provided.


Electromagnetic And Isospin Breaking Effects Decrease Ε′/Ε, John Donoghue, Eugene Golowich, Barry Holstein, J. Trampetic Dec 1985

Electromagnetic And Isospin Breaking Effects Decrease Ε′/Ε, John Donoghue, Eugene Golowich, Barry Holstein, J. Trampetic

John Donoghue

The effects are examined on standard model predictions of ϵ′ which are generated by electromagnetism and by isospin breaking due to quark mass differences. Such corrections are potentially important because the first-order result is strongly suppressed by the ΔI =12 rule. A factor of two or three reduction is found in the predicted value of ϵ′/ϵ.


A New Four Quark Operator=2 Local Operator, John Donoghue, E. Golowich, German Valencia Dec 1985

A New Four Quark Operator=2 Local Operator, John Donoghue, E. Golowich, German Valencia

John Donoghue

We describe a new four-quark IS=2 local operator, which we dub the "dipenguin" operator. Its form is derived and its I 0-to-Eo matrix element is estimated. Also, we comment upon bag-model evaluations of X -to-E matrix elements of ( V—A ) X ( V—A ) operators. 


Is D⁰→Φκ⁻⁰ Really A Clear Signal For The Annihilation Diagram?, John Donoghue Dec 1985

Is D⁰→Φκ⁻⁰ Really A Clear Signal For The Annihilation Diagram?, John Donoghue

John Donoghue

It is shown that rescatteriug effects required by unitarity can produce the reaction Do $F', even when the "8'-exchange" or "annihilation" diagram is not present. This is addressed both in a general context and a specific model. In the latter, it is the mode Do E"q which plays the major role in generating the @Efinal state, as the E'q state is produced using the uu component of the g, and scatters, I/' q E$, by quark exchange, utilizing the ss component of the q. 


Dispersive Effects In D^0 - D^0 Mixing, John Donoghue, E. Golowich, Barry Holstein Dec 1985

Dispersive Effects In D^0 - D^0 Mixing, John Donoghue, E. Golowich, Barry Holstein

John Donoghue

We estimate the size of dispersive effects in hC =2 interactions and find that they represent in fact the dominant components of D -3 mixing. The box diagram is suppressed by several orders of magnitude due to the small values of light-quark masses. Crucial to this argument is a discussion of how the Glashow-Iliopoulos-Maiani mechanism works in the dispersive sector. 


Weak Decays Of The H Dibaryon, John Donoghue, E. Golowich, Barry Holstein Dec 1985

Weak Decays Of The H Dibaryon, John Donoghue, E. Golowich, Barry Holstein

John Donoghue

We calculate decay rates and branching fractions for the postulated S=—2 0dibaryon, both for the expected M=1 channels ( n A, n X,pX ) and for the possible M=2 mode ( nn). For AS= 1 decays we find the S waves are dominated by all = z transitions due to the Pauli principle, which forces the six-quark final state to be in a SU(3) 27-piet. If observed, this would be the first breakdown of the LI = 2 rule. The lifetime is lang, of order 10 ' sec, which should be considered in planning experiments. In the d6'=2 case, we ...


Gravitational Coupling At Finite Temperature, John Donoghue, Barry Holstein, R.W. Robinett Dec 1985

Gravitational Coupling At Finite Temperature, John Donoghue, Barry Holstein, R.W. Robinett

John Donoghue

We discuss a thermodynamic identity which helps explain why (Hiss(Too) at finite temperature. In addition eve complete the discussion of the gravitational force by including the gravitational variation of the temperature. Gradients in the temperature induce extra forces not accounted for by the usual coupling to the energy-momentum tensor. 


Hyperon Decays And Cp Nonconservation, John Donoghue, Xiao-Gang He, Sandip Pakvasa Dec 1985

Hyperon Decays And Cp Nonconservation, John Donoghue, Xiao-Gang He, Sandip Pakvasa

John Donoghue

We study all modes of hyperon nonleptonic decay and consider the CP-odd observables which result. Explicit calculations are provided in the Kobayashi-Maskawa, Weinberg-Higgs, and leftright-symmetric models of CI' nonconservation. 


Splay Rigidity In The Diluted Central Force Elastic Network, Anthony Roy Day, A.-M. S. Tremblay, R. R. Tremblay Dec 1985

Splay Rigidity In The Diluted Central Force Elastic Network, Anthony Roy Day, A.-M. S. Tremblay, R. R. Tremblay

Anthony Roy Day

A Comment on the Letter by Wang and Harris, Phys. Rev. Lett. 55, 2459 (1985).


Chiral Perturbation Theory Corrections To KL→Γγ, John Donoghue Dec 1985

Chiral Perturbation Theory Corrections To KL→Γγ, John Donoghue

John Donoghue

In the calculation of K ° ~ yy to first order in SU(3) breaking, one must include not only ~/-rg mixing but also the first-order corrections to the SU(3) relations for the K --, ~/ and 71 --, y/ transitions. We calculate the leading corrections to these processes at one loop in chiral perturbation theory. Although not large in themselves, they can have potentially large effects in K --* yy due to the cancellations among the leading SU(3) invariant terms. We also comment on corresponding effects on the dispersive part of the K c - K s mass differences.  


Nonequilibrium Fluctuations Studied By A Rarefied Gas Simulation, Alejandro Garcia Dec 1985

Nonequilibrium Fluctuations Studied By A Rarefied Gas Simulation, Alejandro Garcia

Alejandro Garcia

A dilute gas under a constant heat flux is studied with use of a Monte Carlo simulation based on the Boltzmann equation. Results for several spatial correlation functions of equal-time fluctuations are reported and compared qualitatively with previous fluctuating hydrodynamics calculations for liquids.


Renormalization-Group Analysis Of Heat Capacity Amplitude, Scott I. Chase, Miron Kaufman Dec 1985

Renormalization-Group Analysis Of Heat Capacity Amplitude, Scott I. Chase, Miron Kaufman

Miron Kaufman

Critical amplitudes A+ associated with the temperature variation of the heat capacity are analyzed by means of renormalization-group techniques in both position and momentum spaces. We describe a mechanism according to which the amplitudes A diverge as the critical exponent a approaches a nonpositive integer. In between two consecutive divergences at least one amplitude vanishes at least once. The coefficient P in the expansion A+ /A- =1—Pa+0 (a~) is computed by means of e expansion and Migdal-Kadanoff renormalization-group technique. Systems for which the critical exponent alpha is negative but larger than —1 exhibit either a cusped heat capacity ...