10,927 research outputs found
Functional Equations and the Generalised Elliptic Genus
We give a new derivation and characterisation of the generalised elliptic
genus of Krichever-H\"ohn by means of a functional equation.Comment: To be published in the collection honouring Francesco Calogero's
70-th birthda
Testing the Unitarity of the CKM Matrix with a Space-Based Neutron Decay Experiment
If the Standard Model is correct, and fundamental fermions exist only in the
three generations, then the CKM matrix should be unitary. However, there
remains a question over a deviation from unitarity from the value of the
neutron lifetime. We discuss a simple space-based experiment that, at an orbit
height of 500 km above Earth, would measure the kinetic-energy, solid-angle,
flux spectrum of gravitationally bound neutrons (kinetic energy K<0.606 eV at
this altitude). The difference between the energy spectrum of neutrons that
come up from the Earth's atmosphere and that of the undecayed neutrons that
return back down to the Earth would yield a measurement of the neutron
lifetime. This measurement would be free of the systematics of laboratory
experiments. A package of mass kg could provide a 10^{-3} precision in
two years.Comment: 10 pages, 4 figures. Revised and updated for publicatio
LHC discovery potential for models with continuously distributed mass
We study the Large Hadron Collider (LHC) discovery potential for models
with continuously distributed mass for and 14 TeV
centre-of-mass energies. One of possible LHC signatures for such models is the
existence of broad resonance in Drell-Yan reaction .Comment: 14 pages, some references and formula adde
On Collisionless Electron-Ion Temperature Equilibration in the Fast Solar Wind
We explore a mechanism, entirely new to the fast solar wind, of electron
heating by lower hybrid waves to explain the shift to higher charge states
observed in various elements in the fast wind at 1 A.U. relative to the
original coronal hole plasma. This process is a variation on that previously
discussed for two temperature accretion flows by Begelman & Chiueh. Lower
hybrid waves are generated by gyrating minor ions (mainly alpha-particles) and
become significant once strong ion cyclotron heating sets in beyond 1.5 R_sun.
In this way the model avoids conflict with SUMER electron temperature
diagnostic measurements between 1 and 1.5 R_sun. The principal requirement for
such a process to work is the existence of density gradients in the fast solar
wind, with scale length of similar order to the proton inertial length. Similar
size structures have previously been inferred by other authors from radio
scintillation observations and considerations of ion cyclotron wave generation
by global resonant MHD waves.Comment: 32 pages including 11 figures, 4 tables, accepted by Ap
A new approach to analyzing solar coronal spectra and updated collisional ionization equilibrium calculations. II. Additional ionization rate coefficients
We have reanalyzed SUMER observations of a parcel of coronal gas using new
collisional ionization equilibrium (CIE) calculations. These improved CIE
fractional abundances were calculated using state-of-the-art electron-ion
recombination data for K-shell, L-shell, Na-like, and Mg-like ions of all
elements from H through Zn and, additionally, Al- through Ar-like ions of Fe.
They also incorporate the latest recommended electron impact ionization data
for all ions of H through Zn. Improved CIE calculations based on these
recombination and ionization data are presented here. We have also developed a
new systematic method for determining the average emission measure () and
electron temperature () of an isothermal plasma. With our new CIE data and
our new approach for determining average and , we have reanalyzed
SUMER observations of the solar corona. We have compared our results with those
of previous studies and found some significant differences for the derived
and . We have also calculated the enhancement of coronal elemental
abundances compared to their photospheric abundances, using the SUMER
observations themselves to determine the abundance enhancement factor for each
of the emitting elements. Our observationally derived first ionization
potential (FIP) factors are in reasonable agreement with the theoretical model
of Laming (2008).Comment: 147 pages (102 of which are online only tables and figures).
Submitted to ApJ. Version 2 is updated addressing the referee's repor
On the Stability and Single-Particle Properties of Bosonized Fermi Liquids
We study the stability and single-particle properties of Fermi liquids in
spatial dimensions greater than one via bosonization. For smooth non-singular
Fermi liquid interactions we obtain Shankar's renormalization- group flows and
reproduce well known results for quasi-particle lifetimes. We demonstrate by
explicit calculation that spin-charge separation does not occur when the Fermi
liquid interactions are regular. We also explore the relationship between
quantized bosonic excitations and zero sound modes and present a concise
derivation of both the spin and the charge collective mode equations. Finally
we discuss some aspects of singular Fermi liquid interactions.Comment: 13 pages plus three postscript figures appended; RevTex 3.0;
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