770 research outputs found
Precise Determination of Proton Spin-Precession Angles in the K600 Spectrometer and Beamline
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
A Complete Set of In-plane Spin-transfer Coefficients for Small Angle pp Elastic Scattering at 200 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
New primers for promising single-copy genes in fungal phylogenetics and systematics
Developing powerful phylogenetic markers is a key concern in fungal phylogenetics. Here we report degenerate primers that amplify the single-copy genes Mcm7 (MS456) and Tsr1 (MS277) across a wide range of Pezizomycotina (Ascomycota). Phylogenetic analyses of 59 taxa belonging to the Eurotiomycetes, Lecanoromycetes, Leotiomycetes, Lichinomycetes and Sordariomycetes, indicate the utility of these loci for fungal phylogenetics at taxonomic levels ranging from genus to class. We also tested the new primers in silico using sequences of Saccharomycotina, Taphrinomycotina and Basidiomycota to predict their potential of amplifying widely across the Fungi. The analyses suggest that the new primers will need no, or only minor sequence modifications to amplify Saccharomycotina, Taphrinomycotina and Basidiomycota
Medium Effects in the Normal Component Polarization Observables for the 13-C(p,p')13-C, (1/2)- → (9/2)+ Reaction at 200 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Heat-capacity anomalies at and in the ferromagnetic superconductor UGe
The heat-capacity and magnetization measurements under high pressure have
been carried out in a ferromagnetic superconductor UGe. Both measurements
were done using a same pressure cell in order to obtain both data for one
pressure. Contrary to the heat capacity at ambient pressure, an anomaly is
found in the heat capacity at the characteristic temperature where the
magnetization shows an anomalous enhancement under high pressure where the
superconductivity appears. This suggests that a thermodynamic phase transition
takes place at at least under high pressure slightly below
where becomes zero. The heat-capacity anomaly associated with the
superconducting transition is also investigated, where a clear peak of is
observed in a narrow pressure region ( GPa) around
contrary to the previous results of the resistivity measurement.
Present results suggest the importance of the thermodynamic critical point
for the appearance of the superconductivity.Comment: 4 pages, 4 figures, to appear in Phys. Rev. B, Rapid Communication
Connected Green function approach to ground state symmetry breaking in -theory
Using the cluster expansions for n-point Green functions we derive a closed
set of dynamical equations of motion for connected equal-time Green functions
by neglecting all connected functions higher than order for the
-theory in dimensions. We apply the equations to the
investigation of spontaneous ground state symmetry breaking, i.e. to the
evaluation of the effective potential at temperature . Within our momentum
space discretization we obtain a second order phase transition (in agreement
with the Simon-Griffith theorem) and a critical coupling of
as compared to a first order phase transition and
from the Gaussian effective potential approach.Comment: 25 Revtex pages, 5 figures available via fpt from the directory
ugi-94-11 of [email protected] as one postscript file (there
was a bug in our calculations, all numerical results and figures have changed
significantly), ugi-94-1
Hopf algebras and Markov chains: Two examples and a theory
The operation of squaring (coproduct followed by product) in a combinatorial
Hopf algebra is shown to induce a Markov chain in natural bases. Chains
constructed in this way include widely studied methods of card shuffling, a
natural "rock-breaking" process, and Markov chains on simplicial complexes.
Many of these chains can be explictly diagonalized using the primitive elements
of the algebra and the combinatorics of the free Lie algebra. For card
shuffling, this gives an explicit description of the eigenvectors. For
rock-breaking, an explicit description of the quasi-stationary distribution and
sharp rates to absorption follow.Comment: 51 pages, 17 figures. (Typographical errors corrected. Further fixes
will only appear on the version on Amy Pang's website, the arXiv version will
not be updated.
Magnetism in Dense Quark Matter
We review the mechanisms via which an external magnetic field can affect the
ground state of cold and dense quark matter. In the absence of a magnetic
field, at asymptotically high densities, cold quark matter is in the
Color-Flavor-Locked (CFL) phase of color superconductivity characterized by
three scales: the superconducting gap, the gluon Meissner mass, and the
baryonic chemical potential. When an applied magnetic field becomes comparable
with each of these scales, new phases and/or condensates may emerge. They
include the magnetic CFL (MCFL) phase that becomes relevant for fields of the
order of the gap scale; the paramagnetic CFL, important when the field is of
the order of the Meissner mass, and a spin-one condensate associated to the
magnetic moment of the Cooper pairs, significant at fields of the order of the
chemical potential. We discuss the equation of state (EoS) of MCFL matter for a
large range of field values and consider possible applications of the magnetic
effects on dense quark matter to the astrophysics of compact stars.Comment: To appear in Lect. Notes Phys. "Strongly interacting matter in
magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A.
Schmitt, H.-U. Ye
First Measurement of Z/gamma* Production in Compton Scattering of Quasi-real Photons
We report the first observation of Z/gamma* production in Compton scattering
of quasi-real photons. This is a subprocess of the reaction e+e- to
e+e-Z/gamma*, where one of the final state electrons is undetected.
Approximately 55 pb-1 of data collected in the year 1997 at an e+e-
centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been
analysed. The Z/gamma* from Compton scattering has been detected in the
hadronic decay channel. Within well defined kinematic bounds, we measure the
product of cross-section and Z/gamma* branching ratio to hadrons to be
(0.9+-0.3+-0.1) pb for events with a hadronic mass larger than 60 GeV,
dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60
GeV, dominated by (e)egamma* production, this product is found to be
(4.1+-1.6+-0.6) pb. Our results agree with the predictions of two Monte Carlo
event generators, grc4f and PYTHIA.Comment: 18 pages, LaTeX, 5 eps figures included, submitted to Physics Letters
Search for Higgs Bosons in e+e- Collisions at 183 GeV
The data collected by the OPAL experiment at sqrts=183 GeV were used to
search for Higgs bosons which are predicted by the Standard Model and various
extensions, such as general models with two Higgs field doublets and the
Minimal Supersymmetric Standard Model (MSSM). The data correspond to an
integrated luminosity of approximately 54pb-1. None of the searches for neutral
and charged Higgs bosons have revealed an excess of events beyond the expected
background. This negative outcome, in combination with similar results from
searches at lower energies, leads to new limits for the Higgs boson masses and
other model parameters. In particular, the 95% confidence level lower limit for
the mass of the Standard Model Higgs boson is 88.3 GeV. Charged Higgs bosons
can be excluded for masses up to 59.5 GeV. In the MSSM, mh > 70.5 GeV and mA >
72.0 GeV are obtained for tan{beta}>1, no and maximal scalar top mixing and
soft SUSY-breaking masses of 1 TeV. The range 0.8 < tanb < 1.9 is excluded for
minimal scalar top mixing and m{top} < 175 GeV. More general scans of the MSSM
parameter space are also considered.Comment: 49 pages. LaTeX, including 33 eps figures, submitted to European
Physical Journal
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