869 research outputs found
High Density Mesoscopic Atom Clouds in a Holographic Atom Trap
We demonstrate the production of micron-sized high density atom clouds of
interest for meso- scopic quantum information processing. We evaporate atoms
from 60 microK, 3x10^14 atoms/cm^3 samples contained in a highly anisotropic
optical lattice formed by interfering di racted beams from a holographic phase
plate. After evaporating to 1 microK by lowering the con ning potential, in
less than a second the atom density reduces to 8x10^13 cm^- 3 at a phase space
density approaching unity. Adiabatic recompression of the atoms then increases
the density to levels in excess of 1x10^15 cm^-3. The resulting clouds are
typically 8 microns in the longest dimension. Such samples are small enough to
enable mesoscopic quantum manipulation using Rydberg blockade and have the high
densities required to investigate new collision phenomena.Comment: 4 pages, 4 figures, submitted to PR
Slow magnetoacoustic waves in coronal loops : EIT and TRACE
On May 13, 1998 the EIT (Extreme ultraviolet Imaging Telescope) on board of SoHO (Solar and Heliospheric Observatory) and TRACE (Transition Region And Coronal Explorer) instruments produced simultaneous high cadence image sequences of the same active region (AR 8218). TRACE achieved a 25 s cadence in the FeIX (171 Ă…) bandpass while EIT achieved a 15 s cadence (operating in "shutterless mode", SoHO JOP 80) in the FeXII (195 Ă…) bandpass. These high cadence observations in two complementary wavelengths have revealed the existence of weak transient disturbances in an extended coronal loop system. These propagating disturbances (PDs) seem to be a common phenomenon in this part of the active region. The disturbances originate from small scale brightenings at the footpoints of the loops and propagate along the loops. The projected propagation speeds roughly vary between 65 and 150 km s-1 for both instruments which is close to and below the expected sound speed in the coronal loops. The measured slow magnetoacoustic propagation speeds seem to suggest that the transients are sound (or slow) wave disturbances. This work differs from previous studies in the sense that it is based on a multi-wavelength observation of an entire loop bundle at high cadence by two EUV imagers. The observation of sound waves along the same path shows that they propagate along the same loop, suggesting that loops contain sharp temperature gradients and consist of either concentric shells or thin loop threads, at different temperatures
Nonlocal Dynamics of p-Adic Strings
We consider the construction of Lagrangians that might be suitable for
describing the entire -adic sector of an adelic open scalar string. These
Lagrangians are constructed using the Lagrangian for -adic strings with an
arbitrary prime number . They contain space-time nonlocality because of the
d'Alembertian in argument of the Riemann zeta function. We present a brief
review and some new results.Comment: 8 page
Thermal Duality and Hagedorn Transition from p-adic Strings
We develop the finite temperature theory of p-adic string models. We find
that the thermal properties of these non-local field theories can be
interpreted either as contributions of standard thermal modes with energies
proportional to the temperature, or inverse thermal modes with energies
proportional to the inverse of the temperature, leading to a "thermal duality"
at leading order (genus one) analogous to the well known T-duality of string
theory. The p-adic strings also recover the asymptotic limits (high and low
temperature) for arbitrary genus that purely stringy calculations have yielded.
We also discuss our findings surrounding the nature of the Hagedorn transition.Comment: 4 pages and 4 figure
p-Adic and Adelic Harmonic Oscillator with Time-Dependent Frequency
The classical and quantum formalism for a p-adic and adelic harmonic
oscillator with time-dependent frequency is developed, and general formulae for
main theoretical quantities are obtained. In particular, the p-adic propagator
is calculated, and the existence of a simple vacuum state as well as adelic
quantum dynamics is shown. Space discreteness and p-adic quantum-mechanical
phase are noted.Comment: 10 page
Zeta Nonlocal Scalar Fields
We consider some nonlocal and nonpolynomial scalar field models originated
from p-adic string theory. Infinite number of spacetime derivatives is
determined by the operator valued Riemann zeta function through d'Alembertian
in its argument. Construction of the corresponding Lagrangians L starts
with the exact Lagrangian for effective field of p-adic tachyon
string, which is generalized replacing p by arbitrary natural number n and then
taken a sum of over all n. The corresponding new objects we
call zeta scalar strings. Some basic classical field properties of these fields
are obtained and presented in this paper. In particular, some solutions of the
equations of motion and their tachyon spectra are studied. Field theory with
Riemann zeta function dynamics is interesting in its own right as well.Comment: 13 pages, submitted to Theoretical and Mathematical Physic
Baryon Octet magnetic moments in PT: More on the importance of the Decuplet
We address the impact of treating the decuplet of spin-3/2 baryons as an
explicit degree of freedom in the chiral expansion of the magnetic moments of
the octet of spin-1/2 baryons. We carry out a complete calculation of the octet
moments to O(1/\lamchic), including decuplet contributions to the chiral loops.
In contrast to results of previous analyses, we find that inclusion of the
decuplet preserves the convergence behavior of the chiral expansion implied by
power counting arguments.Comment: 17 pages, 2 figures. Includes axodraw.sty needed for figures Minor
typos correcte
Strangeness Content in the Nucleon
I review recent studies of strangeness content in the nucleon pertaining to
the flavor-singlet , the matrix element and the strangeness
electric and magnetic form factors and , based on
lattice QCD calculations. I shall also discuss the relevance of incorporating
the strangeness content in nuclei in regard to strange baryon-antibaryon
productions from proton-nucleus and nucleus-nucleus collisions at SPS and RHIC
energies.Comment: 11 pages, 4 figures, Invited talk at V Int. Conf. on Strangeness in
Quark Matter, Berkeley, CA, July 20--25, 200
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