98 research outputs found
Projection and ground state correlations made simple
We develop and test efficient approximations to estimate ground state
correlations associated with low- and zero-energy modes. The scheme is an
extension of the generator-coordinate-method (GCM) within Gaussian overlap
approximation (GOA). We show that GOA fails in non-Cartesian topologies and
present a topologically correct generalization of GOA (topGOA). An RPA-like
correction is derived as the small amplitude limit of topGOA, called topRPA.
Using exactly solvable models, the topGOA and topRPA schemes are compared with
conventional approaches (GCM-GOA, RPA, Lipkin-Nogami projection) for
rotational-vibrational motion and for particle number projection. The results
shows that the new schemes perform very well in all regimes of coupling.Comment: RevTex, 12 pages, 7 eps figure
Signatures of the slow solar wind streams from active regions in the inner corona
Some of local sources of the slow solar wind can be associated with
spectroscopically detected plasma outflows at edges of active regions
accompanied with specific signatures in the inner corona. The EUV telescopes
(e.g. SPIRIT/CORONAS-F, TESIS/CORONAS-Photon and SWAP/PROBA2) sometimes
observed extended ray-like structures seen at the limb above active regions in
1MK iron emission lines and described as "coronal rays". To verify the
relationship between coronal rays and plasma outflows, we analyze an isolated
active region (AR) adjacent to small coronal hole (CH) observed by different
EUV instruments in the end of July - beginning of August 2009. On August 1 EIS
revealed in the AR two compact outflows with the Doppler velocities V =10-30
km/s accompanied with fan loops diverging from their regions. At the limb the
ARCH interface region produced coronal rays observed by EUVI/STEREO-A on July
31 as well as by TESIS on August 7. The rays were co-aligned with open magnetic
field lines expanded to the streamer stalks. Using the DEM analysis, it was
found that the fan loops diverged from the outflow regions had the dominant
temperature of ~1 MK, which is similar to that of the outgoing plasma streams.
Parameters of the solar wind measured by STEREO-B, ACE, WIND, STEREO-A were
conformed with identification of the ARCH as a source region at the
Wang-Sheeley-Arge map of derived coronal holes for CR 2086. The results of the
study support the suggestion that coronal rays can represent signatures of
outflows from ARs propagating in the inner corona along open field lines into
the heliosphere.Comment: Accepted for publication in Solar Physics; 31 Pages; 13 Figure
Update of the Search for the Neutrinoless Decay
We present an update of the search for the lepton family number violating
decay using a complete CLEO II data sample of 12.6 million
pairs. No evidence of a signal has been found and the
corresponding upper limit is \BR(\tau \to \mu\gamma) < 1.0 \times 10^{-6}
at 90% CL, significantly smaller than previous limits. All quoted results are
preliminary.Comment: 9 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Search for charged Higgs bosons in top quark decays
We present a search for charged Higgs bosons in top quark decays. We analyze
the \eplus, \muplus, , , , \etau and \mutau final states from
top quark pair production events, using data from about 1 of
integrated luminosity recorded by the \dzero experiment at the Fermilab
Tevatron Collider. We consider different scenarios of possible charged Higgs
boson decays, one where the charged Higgs boson decays purely hadronically into
a charm and a strange quark, another where it decays into a lepton and a
neutrino and a third one where both decays appear. We extract limits on
the branching ratio for all these models. We use two methods,
one where the production cross section is fixed, and one where the
cross section is fitted simultaneously with . Based on the
extracted limits, we exclude regions in the charged Higgs boson mass and parameter space for different scenarios of the minimal supersymmetric
standard model.Comment: 10 pages, 8 figures, submitted to PL
Solar parameters for modeling interplanetary background
The goal of the Fully Online Datacenter of Ultraviolet Emissions (FONDUE)
Working Team of the International Space Science Institute in Bern, Switzerland,
was to establish a common calibration of various UV and EUV heliospheric
observations, both spectroscopic and photometric. Realization of this goal
required an up-to-date model of spatial distribution of neutral interstellar
hydrogen in the heliosphere, and to that end, a credible model of the radiation
pressure and ionization processes was needed. This chapter describes the solar
factors shaping the distribution of neutral interstellar H in the heliosphere.
Presented are the solar Lyman-alpha flux and the solar Lyman-alpha resonant
radiation pressure force acting on neutral H atoms in the heliosphere, solar
EUV radiation and the photoionization of heliospheric hydrogen, and their
evolution in time and the still hypothetical variation with heliolatitude.
Further, solar wind and its evolution with solar activity is presented in the
context of the charge exchange ionization of heliospheric hydrogen, and in the
context of dynamic pressure variations. Also the electron ionization and its
variation with time, heliolatitude, and solar distance is presented. After a
review of all of those topics, we present an interim model of solar wind and
the other solar factors based on up-to-date in situ and remote sensing
observations of solar wind. Results of this effort will further be utilised to
improve on the model of solar wind evolution, which will be an invaluable asset
in all heliospheric measurements, including, among others, the observations of
Energetic Neutral Atoms by the Interstellar Boundary Explorer (IBEX).Comment: Chapter 2 in the planned "Cross-Calibration of Past and Present Far
UV Spectra of Solar System Objects and the Heliosphere", ISSI Scientific
Report No 12, ed. R.M. Bonnet, E. Quemerais, M. Snow, Springe
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