17,235 research outputs found
Measuring multipole moments of Weyl metrics by means of gyroscopes
Using the technique of Rindler and Perlick we calculate the total precession
per revolution of a gyroscope circumventing the source of Weyl metrics. We
establish thereby a link between the multipole moments of the source and an
``observable'' quantity. Special attention deserves the case of the
gamma-metric. As an extension of this result we also present the corresponding
expressions for some stationary space-times.Comment: 18 pages Latex, To appear in J.Math.Phy
Finite-size scaling for the left-current correlator with non-degenerate quark masses
We study the volume dependence of the left-current correlator with
non-degenerate quark masses to next-to-leading order in the chiral expansion.
We consider three possible regimes: all quark masses are in the
-regime, all are in the -regime and a mixed-regime where the
lighest quark masses satisfy while the heavier . These results can be used to match lattice QCD and the Chiral
Effective Theory in a large but finite box in which the Compton wavelength of
the lightest pions is of the order of the box size. We consider both the full
and partially-quenched results.Comment: 27 pages, 4 figure
Non-spherical sources of static gravitational fields: investigating the boundaries of the no-hair theorem
A new, globally regular model describing a static, non spherical gravitating
object in General Relativity is presented. The model is composed by a vacuum
Weyl--Levi-Civita special field - the so called gamma metric - generated by a
regular static distribution of mass-energy. Standard requirements of physical
reasonableness such as, energy, matching and regularity conditions are
satisfied. The model is used as a toy in investigating various issues related
to the directional behavior of naked singularities in static spacetimes and the
blackhole (Schwarschild) limit.Comment: 10 pages, 2 figure
A source of a quasi--spherical space--time: The case for the M--Q solution
We present a physically reasonable source for an static, axially--symmetric
solution to the Einstein equations. Arguments are provided, supporting our
belief that the exterior space--time produced by such source, describing a
quadrupole correction to the Schwarzschild metric, is particularly suitable
(among known solutions of the Weyl family) for discussing the properties of
quasi--spherical gravitational fields.Comment: 34 pages, 9 figures. To appear in GR
Has a Higgs-flavon with a GeV mass been detected at the LHC13?
Higgs-flavon fields appear as a part of the Froggatt-Nielsen (FN) mechanism,
which attempts to explain the hierarchy of Yukawa couplings. We explore the
possibility that the 750 GeV diphoton resonance recently reported at the LHC13,
could be identified with a low-scale Higgs-flavon field and find the
region of the parameter space consistent with CMS and ATLAS data. It is found
that the extra vector-like fermions of the ultraviolet completion of the FN
mechanism are necessary in order to reproduce the observed signal. We consider
a standard model (SM) extension that contains two Higgs doublets (a standard
one and an inert one) and one complex FN singlet. The inert doublet includes a
stable neutral boson, which provides a viable dark matter candidate, while the
mixing of the standard doublet and the FN singlet induces flavor violation in
the Higgs sector at the tree-level. Constraints on the parameters of the model
are derived from the LHC Higgs data, which include the search for the lepton
flavor violating decay of the SM Higgs boson . It is also
found that in some region of the parameter space the model may give rise to a
large branching ratio for the decay, of the order of 0.1, which
could be searched for at the LHC.Comment: 18 pages, 7 Figures, includes updated files to match published
versio
Approximate gravitational field of a rotating deformed mass
A new approximate solution of vacuum and stationary Einstein field equations
is obtained. This solution is constructed by means of a power series expansion
of the Ernst potential in terms of two independent and dimensionless parameters
representing the quadrupole and the angular momentum respectively. The main
feature of the solution is a suitable description of small deviations from
spherical symmetry through perturbations of the static configuration and the
massive multipole structure by using those parameters. This quality of the
solution might eventually provide relevant differences with respect to the
description provided by the Kerr solution.Comment: 16 pages. Latex. To appear in General Relativity and Gravitatio
The antifield Koszul-Tate complex of reducible Noether identities
A generic degenerate Lagrangian system of even and odd fields is examined in
algebraic terms of the Grassmann-graded variational bicomplex. Its
Euler-Lagrange operator obeys Noether identities which need not be independent,
but satisfy first-stage Noether identities, and so on. We show that, if a
certain necessary and sufficient condition holds, one can associate to a
degenerate Lagrangian system the exact Koszul-Tate complex with the boundary
operator whose nilpotency condition restarts all its Noether and higher-stage
Noether identities. This complex provides a sufficient analysis of the
degeneracy of a Lagrangian system for the purpose of its BV quantization.Comment: 23 page
Noether's second theorem for BRST symmetries
We present Noether's second theorem for graded Lagrangian systems of even and
odd variables on an arbitrary body manifold X in a general case of BRST
symmetries depending on derivatives of dynamic variables and ghosts of any
finite order. As a preliminary step, Noether's second theorem for Lagrangian
systems on fiber bundles over X possessing gauge symmetries depending on
derivatives of dynamic variables and parameters of arbitrary order is proved.Comment: 31 pages, to be published in J. Math. Phy
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