146 research outputs found
Local Couplings and Sl(2,R) Invariance for Gauge Theories at One Loop
The response of the one loop effective action for a gauge theory with local
couplings under a local Weyl rescaling of the background
metric is calculated. Apart from terms which may be removed by local
contributions to the effective action the result is compatible with
symmetry acting on . Two loop effects are also discussed.Comment: 10 pages, uses harvma
Heavy Handed Quest for Fixed Points in Multiple Coupling Scalar Theories in the Expansion
The tensorial equations for non trivial fully interacting fixed points at
lowest order in the expansion in and
dimensions are analysed for -component fields and
corresponding multi-index couplings which are symmetric tensors with
four or six indices. Both analytic and numerical methods are used. For
in the four-index case large numbers of irrational fixed points are
found numerically where is close to the bound found by Rychkov
and Stergiou in arXiv:1810.10541. No solutions, other than those already known,
are found which saturate the bound. These examples in general do not have
unique quadratic invariants in the fields. For the stability
matrix in the full space of couplings always has negative eigenvalues. In the
six index case the numerical search generates a very large number of solutions
for .Comment: 50 pages, 6 figures. v2: 53 pages, 6 figures; Expanded discussion of
N=4 case including splitting of fixed point at order ; v4:
Minor corrections and addition
Modified Weak Energy Condition for the Energy Momentum Tensor in Quantum Field Theory
The weak energy condition is known to fail in general when applied to
expectation values of the the energy momentum tensor in flat space quantum
field theory. It is shown how the usual counter arguments against its validity
are no longer applicable if the states |\psi \r for which the expectation
value is considered are restricted to a suitably defined subspace. A possible
natural restriction on |\psi \r is suggested and illustrated by two quantum
mechanical examples based on a simple perturbed harmonic oscillator
Hamiltonian. The proposed alternative quantum weak energy condition is applied
to states formed by the action of scalar, vector and the energy momentum tensor
operators on the vacuum. We assume conformal invariance in order to determine
almost uniquely three-point functions involving the energy momentum tensor in
terms of a few parameters. The positivity conditions lead to non trivial
inequalities for these parameters. They are satisfied in free field theories,
except in one case for dimensions close to two. Further restrictions on |\psi
\r are suggested which remove this problem. The inequalities which follow from
considering the state formed by applying the energy momentum tensor to the
vacuum are shown to imply that the coefficient of the topological term in the
expectation value of the trace of the energy momentum tensor in an arbitrary
curved space background is positive, in accord with calculations in free field
theories.Comment: 27 pages, 1 figure, uses harvmac, epsf and boldmath (included).
Change of title and some text changes, form to be publishe
N=1 Superconformal Symmetry in Four Dimensional Quantum Field Theory
The implications of N=1 superconformal symmetry for four dimensional quantum
field theories are studied. Superconformal covariant expressions for two and
three point functions of quasi-primary superfields of arbitrary spin are found
and connected with the operator product expansion. The general formulae are
specialised to cases involving a scalar superfield L, which contains global
symmetry currents, and the supercurrent, which contains the energy momentum
tensor, and the consequences of superconformal Ward identities analysed. The
three point function of L is shown to have unique completely antisymmetric or
symmetric forms. In the latter case the superspace version of the axial anomaly
equation is obtained. The three point function for the supercurrent is shown to
have two linearly independent forms. A linear combination of the associated
coefficients for the general expression is shown to be related to the scale of
the supercurrent two point function through Ward identities. The coefficients
are given for the two free field superconformal theories and are also connected
with the parameters present in the supercurrent anomaly for supergravity
backgrounds. Superconformal invariants, which are possible even in three point
functions, are discussed.Comment: 53 pages, uses harvmac, revised version includes further corrections
and minor additions, version to be publishe
The host stars of Kepler's habitable exoplanets : superflares, rotation and activity
We embark on a detailed study of the light curves of Kepler's most Earth-like exoplanet host stars using the full length of Kepler data. We derive rotation periods, photometric activity indices, flaring energies, mass-loss rates, gyrochronological ages, X-ray luminosities and consider implications for the planetary magnetospheres and habitability. Furthermore, we present the detection of superflares in the light curve of Kepler-438, the exoplanet with the highest Earth Similarity Index to date. Kepler-438b orbits at a distance of 0.166 au to its host star, and hence may be susceptible to atmospheric stripping. Our sample is taken from the Habitable Exoplanet Catalogue, and consists of the stars Kepler-22, Kepler-61, Kepler-62, Kepler-174, Kepler-186, Kepler-283, Kepler-296, Kepler-298, Kepler-438, Kepler-440, Kepler-442, Kepler-443 and KOI-4427, between them hosting 15 of the most habitable transiting planets known to date from Kepler
Absorbent particles, especially catamenials, having improved fluid directionality, comfort and fit
Absorbent articles, especially sanitary napkins, contain fibers with intra-fiber capillary channels. In-use, the capillary channel fibers direct menses to a storage layer, thereby minimizing product failure and staining of undergarments. The capillary channel fibers can protrude into, or through, a topsheet to provide very aggressive transport of vaginal discharges
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