9,730 research outputs found
Finiteness in N=1 SYM Theories
I present a criterion for all-order finiteness in N=1 SYM theories. Three
applications are given; they yield all-order finite N=1 SYM models with global
symmetries of the superpotential.Comment: 3 pages, plain LaTex, no figure
Q-Exact Actions for BF Theories
The actions for all classical (and consequently quantum) theories on
-manifolds is proven to be given by anti-commutators of hermitian,
nilpotent, scalar fermionic charges with Grassmann-odd functionals. In order to
show this, the space of fields in the theory must be enlarged to include ``mass
terms'' for new, non-dynamical, Grassmann-odd fields. The implications of this
result on observables are examined.Comment: 12 pgs., LaTeX, MIT-CTP-227
On the use of Ajisai and Jason-1 satellites for tests of General Relativity
Here we analyze in detail some aspects of the proposed use of Ajisai and
Jason-1, together with the LAGEOS satellites, to measure the general
relativistic Lense-Thirring effect in the gravitational field of the Earth. A
linear combination of the nodes of such satellites is the proposed observable.
The systematic error due to the mismodelling in the uncancelled even zonal
harmonics would be \sim 1% according to the latest present-day
CHAMP/GRACE-based Earth gravity models. In regard to the non-gravitational
perturbations especially affecting Jason-1, only relatively high-frequency
harmonic perturbations should occur: neither semisecular nor secular bias of
non-gravitational origin should affect the proposed combination: their maximum
impact is evaluated to \sim 4% over 2 years. Our estimation of the
root-sum-square total error is about 4-5% over at least 3 years of data
analysis required to average out the uncancelled tidal perturbations.Comment: Latex, 24 pages, 5 tables, 1 figure. Two references added, minor
modifications. To appear in New Astronom
The impact of the new Earth gravity models on the measurement of the Lense-Thirring effect with a new satellite
In this paper we investigate the opportunities offered by the new Earth
gravity models from the dedicated CHAMP and, especially, GRACE missions to the
project of measuring the general relativistic Lense-Thirring effect with a new
Earth's artificial satellite. It turns out that it would be possible to abandon
the stringent, and expensive, requirements on the orbital geometry of the
originally prosed LARES mission (same semimajor axis a=12270 km of the existing
LAGEOS and inclination i=70 deg) by inserting the new spacecraft in a
relatively low, and cheaper, orbit (a=7500-8000 km, i\sim 70 deg) and suitably
combining its node Omega with those of LAGEOS and LAGEOS II in order to cancel
out the first even zonal harmonic coefficients of the multipolar expansion of
the terrestrial gravitational potential J_2, J_4 along with their temporal
variations. The total systematic error due to the mismodelling in the remaining
even zonal harmonics would amount to \sim 1% and would be insensitive to
departures of the inclination from the originally proposed value of many
degrees. No semisecular long-period perturbations would be introduced because
the period of the node, which is also the period of the solar K_1 tidal
perturbation, would amount to \sim 10^2 days. Since the coefficient of the node
of the new satellite would be smaller than 0.1 for such low altitudes, the
impact of the non-gravitational perturbations of it on the proposed combination
would be negligible. Then, a particular financial and technological effort for
suitably building the satellite in order to minimize the non-conservative
accelerations would be unnecessary.Comment: LaTex2e, 28 pages, 2 tables, 8 figures. To appear in New Astronom
Many-Body Entanglement in Short-Range Interacting Fermi Gases for Metrology
We explore many-body entanglement in spinful Fermi gases with short-range
interactions, for metrology purposes. We characterize the emerging quantum
phases via Density-Matrix Renormalization Group simulations and quantify their
entanglement content for metrological usability via the Quantum Fisher
Information (QFI). Our study establishes a method, promoting the QFI to be an
order parameter. Short-range interactions reveal to build up metrologically
promising entanglement in the XY-ferromagnetic and cluster ordering, the
cluster physics being unexplored so far.Comment: 5 pages, 4 figures + 10 pages, 8 figures of supplementa
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