2,630 research outputs found
Gribov horizon and non-perturbative BRST symmetry in the maximal Abelian gauge
The non-perturbative nilpotent exact BRST symmetry of the Gribov-Zwanziger
action in the Landau gauge constructed in [ arXiv:1506.06995 [hep-th]] is
generalized to the case of Euclidean Yang-Mills theories quantized in the
maximal Abelian gauge. The resulting diagonal gluon propagator is evaluating in
dimensions D=4,3,2. In D=4,3 a decoupling type behavior is found in the
infrared region, while in D=2 a scaling type behavior emerges.Comment: Reviewed version with a new section and new references adde
Helioseismology and the solar age
The problem of measuring the solar age by means of helioseismology hasbeen
recently revisited by Guenther & Demarque (1997) and by Weiss & Schlattl
(1998). Different best values for and different assessment of
the uncertainty resulted from these two works. We show that depending on the
way seismic data are used, one may obtain the value
Gy, close to the age of the oldest meteorites, Gy, like in
the first paper, or above 5 Gy like in the second paper. The discrepancy in the
seismic estimates of the solar age may be eliminated by assuming higher than
the standard metal abundance and/or an upward revision of the opacities in the
solar radiative interior.We argue that the most accurate and robust seismic
measure of the solar age are the small frequency separations,
, for spherical harmonic degrees
and radial orders .The seismic age inferred by
minimization of the sum of squared differences between the model and the solar
small separations is , a number consistent with
meteoritic data.Our analysis supports earlier suggestions of using small
frequency separations as stellar age indicators.Comment: 8 pages + 4 ps figures included, LaTeX file with l-aa.sty, submitted
to Astronomy and Astrophysic
Extracting convergent surface energies from slab calculations
The formation energy of a solid surface can be extracted from slab
calculations if the bulk energy per atom is known. It has been pointed out
previously that the resulting surface energy will diverge with slab thickness
if the bulk energy is in error, in the context of calculations which used
different methods to study the bulk and slab systems. We show here that this
result is equally relevant for state-of-the-art computational methods which
carefully treat bulk and slab systems in the same way. Here we compare
different approaches, and present a solution to the problem that eliminates the
divergence and leads to rapidly convergent and accurate surface energies.Comment: 3 revtex pages, 1 figure, in print on J. Phys. Cond. Mat
A non-perturbative study of matter field propagators in Euclidean Yang-Mills theory in linear covariant, Curci-Ferrari and maximal Abelian gauges
In this work, we study the propagators of matter fields within the framework
of the Refined Gribov-Zwanziger theory, which takes into account the effects of
the Gribov copies in the gauge-fixing quantization procedure of Yang-Mills
theory. In full analogy with the pure gluon sector of the Refined
Gribov-Zwanziger action, a non-local long-range term in the inverse of the
Faddeev-Popov operator is added in the matter sector. Making use of the recent
BRST invariant formulation of the Gribov-Zwanziger framework achieved in [Capri
et al 2016], the propagators of scalar and quark fields in the adjoint and
fundamental representations of the gauge group are worked out explicitly in the
linear covariant, Curci-Ferrari and maximal Abelian gauges. Whenever lattice
data are available, our results exhibit good qualitative agreement.Comment: 27 pages, no figures; V2, minor modifications, to appear in EPJ
Mantle geoneutrinos in KamLAND and Borexino
The KamLAND and Borexino experiments have observed, each at ~4 sigma level,
signals of electron antineutrinos produced in the decay chains of thorium and
uranium in the Earth's crust and mantle (Th and U geoneutrinos). Various pieces
of geochemical and geophysical information allow an estimation of the crustal
geoneutrino flux components with relatively small uncertainties. The mantle
component may then be inferred by subtracting the estimated crustal flux from
the measured total flux. To this purpose, we analyze in detail the experimental
Th and U geoneutrino event rates in KamLAND and Borexino, including neutrino
oscillation effects. We estimate the crustal flux at the two detector sites,
using state-of-the-art information about the Th and U distribution on global
and local scales. We find that crust-subtracted signals show hints of a
residual mantle component, emerging at ~2.4 sigma level by combining the
KamLAND and Borexino data. The inferred mantle flux slightly favors scenarios
with relatively high Th and U abundances, within +-1 sigma uncertainties
comparable to the spread of predictions from recent mantle models.Comment: Slight changes and improvements in the text & figures. Results
unchanged. To appear in Phys. Rev.
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