869 research outputs found

    High Density Mesoscopic Atom Clouds in a Holographic Atom Trap

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    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

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    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

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    We consider the construction of Lagrangians that might be suitable for describing the entire pp-adic sector of an adelic open scalar string. These Lagrangians are constructed using the Lagrangian for pp-adic strings with an arbitrary prime number pp. 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

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    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

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    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

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    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 â–ˇ\Box in its argument. Construction of the corresponding Lagrangians L starts with the exact Lagrangian Lp\mathcal{L}_p for effective field of p-adic tachyon string, which is generalized replacing p by arbitrary natural number n and then taken a sum of Ln\mathcal{L}_n 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 χ\chiPT: More on the importance of the Decuplet

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    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

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    I review recent studies of strangeness content in the nucleon pertaining to the flavor-singlet gA0g_A^0, the sˉs\bar{s}s matrix element and the strangeness electric and magnetic form factors GEs(q2)G_E^s(q^2) and GMs(q2)G_M^s(q^2), 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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