686 research outputs found
Finite temperature behaviour of glueballs in Lattice Gauge Theories
We propose a new method to compute glueball masses in finite temperature
Lattice Gauge Theories which at low temperature is fully compatible with the
known zero temperature results and as the temperature increases leads to a
glueball spectrum which vanishes at the deconfinement transition. We show that
this definition is consistent with the Isgur-Paton model and with the expected
contribution of the glueball spectrum to various thermodynamic quantities at
finite temperature. We test our proposal with a set of high precision numerical
simulations in the 3d gauge Ising model and find a good agreement with our
predictions.Comment: 4 pages, 4 figure
Local field enhancement: comparing self-similar and dimer nanoantennas
We study the local field enhancement properties of self-similar nanolenses
and compare the obtained results with the performance of standard dimer
nanoantennas. We report that, despite the additional structural complexity,
self-similar nanolenses are unable to provide significant improvements over the
field enhancement performance of standard plasmonic dimers
A different kind of string
In U(1) lattice gauge theory in three spacetime dimensions, the problem of
confinement can be studied analytically in a semi-classical approach, in terms
of a gas of monopoles with Coulomb-like interactions. In addition, this theory
can be mapped to a spin model via an exact duality transformation, which allows
one to perform high-precision numerical studies of the confining potential.
Taking advantage of these properties, we carried out an accurate investigation
of the effective string describing the low-energy properties of flux tubes in
this confining gauge theory. We found striking deviations from the expected
Nambu-Goto-like behavior, and, for the first time, evidence for contributions
that can be described by a term proportional to the extrinsic curvature of the
effective string worldsheet. Such term is allowed by Lorentz invariance, and
its presence in the infrared regime of the U(1) model was indeed predicted by
Polyakov several years ago. Our results show that this term scales as expected
according to Polyakov's solution, and becomes the dominant contribution to the
effective string action in the continuum limit. We also demonstrate
analytically that the corrections to the confining potential induced by the
extrinsic curvature term can be related to the partition function of the
massive perturbation of a c=1 bosonic conformal field theory. The implications
of our results for SU(N) Yang-Mills theories in three and in four spacetime
dimensions are discussed.Comment: 1+21 pages, 2 figures; v2 (1+24 pages, 2 figures): improved the
discussion in the conclusions' section, added an appendix, included new
references, updated the affiliation details for one of the authors, corrected
typos: version published in the journa
Fine structure of the confining string in an analytically solvable 3D model
In lattice gauge theory in three spacetime dimensions,
confinement can be analytically shown to persist at all values of the coupling.
Furthermore, the explicit predictions for the dependence of string tension
and mass gap on the coupling allow one to tune their ratio at
will. These features, and the possibility of obtaining high-precision numerical
results via an exact duality map to a spin model, make this theory an ideal
laboratory to test the effective string description of confining flux tubes. In
this contribution, we discuss our investigation of next-to-leading-order
corrections to the confining potential and of the finite-temperature behavior
of the flux tube width. Our data provide a very stringent test of the
theoretical predictions for these quantities and allow to test their dependence
on the ratio.Comment: Presented at the 31st International Symposium on Lattice Field Theory
(Lattice 2013), 29 July - 3 August 2013, Mainz, German
Effective string description of the interquark potential in the 3D U(1) lattice gauge theory
The U(1) lattice gauge theory in three dimensions is a perfect laboratory to
study the properties of the confining string. On the one hand, thanks to the
mapping to a Coulomb gas of monopoles, the confining properties of the model
can be studied semi-classically. On the other hand, high-precision numerical
estimates of Polyakov loop correlators can be obtained via a duality map to a
spin model. This allowed us to perform high-precision tests of the universal
behavior of the effective string and to find macroscopic deviations with
respect to the expected Nambu-Goto predictions. These corrections could be
fitted with very good precision including a contribution (which is consistent
with Lorentz symmetry) proportional to the square of the extrinsic curvature in
the effective string action, as originally suggested by Polyakov. Performing
our analysis at different values of we were able to show that this term
scales as expected by Polyakov's solution and dominates in the continuum. We
also discuss the interplay between the extrinsic curvature contribution and the
boundary correction induced by the Polyakov loops.Comment: 7 pages, 2 pdf figures, contribution to the 32nd International
Symposium on Lattice Field Theory "Lattice 2014" (23-28 June 2014, Columbia
University, New York, NY, USA
Exceptional thermodynamics: The equation of state of G(2) gauge theory
We present a lattice study of the equation of state in Yang-Mills theory
based on the exceptional G(2) gauge group. As is well-known, at zero
temperature this theory shares many qualitative features with real-world QCD,
including the absence of colored states in the spectrum and dynamical string
breaking at large distances. In agreement with previous works, we show that at
finite temperature this theory features a first-order deconfining phase
transition, whose nature can be studied by a semi-classical computation. We
also show that the equilibrium thermodynamic observables in the deconfined
phase bear striking quantitative similarities with those found in SU(N) gauge
theories: in particular, these quantities exhibit nearly perfect
proportionality to the number of gluon degrees of freedom, and the trace
anomaly reveals a characteristic quadratic dependence on the temperature, also
observed in SU(N) Yang-Mills theories (both in four and in three spacetime
dimensions). We compare our lattice data with analytical predictions from
effective models, and discuss their implications for the deconfinement
mechanism and high-temperature properties of strongly interacting,
non-supersymmetric gauge theories. Our results give strong evidence for the
conjecture that the thermal deconfining transition is governed by a universal
mechanism, common to all simple gauge groups.Comment: 1+36 pages, 8 figures; v2, 1+41 pages, 9 figures: scale setting
improved, discussion in section 1 slightly expanded, comments on the Monte
Carlo algorithm added, new references included, affiliation details for one
of the authors updated, minor misprints corrected: version published in the
journa
The stellar initial mass function of early type galaxies from low to high stellar velocity dispersion: homogeneous analysis of ATLAS and Sloan Lens ACS galaxies
We present an investigation about the shape of the initial mass function
(IMF) of early-type galaxies (ETGs), based on a joint lensing and dynamical
analysis, and on stellar population synthesis models, for a sample of 55 lens
ETGs identified by the Sloan Lens ACS (SLACS) Survey. We construct axisymmetric
dynamical models based on the Jeans equations which allow for orbital
anisotropy and include a dark matter halo. The models reproduce in detail the
observed \textit{HST} photometry and are constrained by the total projected
mass within the Einstein radius and the stellar velocity dispersion ()
within the SDSS fibers. Comparing the dynamically-derived stellar mass-to-light
ratios , obtained for an assumed halo slope , to the stellar population ones , derived
from full-spectrum fitting and assuming a Salpeter IMF, we infer the mass
normalization of the IMF. Our results confirm the previous analysis by the
SLACS team that the mass normalization of the IMF of high galaxies is
consistent on average with a Salpeter slope. Our study allows for a fully
consistent study of the trend between IMF and for both the SLACS and
\ATLAS samples, which explore quite different ranges. The two samples
are highly complementary, the first being essentially selected, and
the latter volume-limited and nearly mass selected. We find that the two
samples merge smoothly into a single trend of the form , where and is the luminosity averaged
within one effective radius . This is consistent with a
systematic variation of the IMF normalization from Kroupa to Salpeter in the
interval .Comment: 18 pages, 8 figures. Accepted for publication in MNRA
Chiral Surface Waves for Enhanced Circular Dichroism
We present a novel chiral sensing platform that combines a one-dimensional
photonic crystal design with a birefringent surface defect. The platform
sustains simultaneous transverse electric and transverse magnetic surface
modes, which are exploited to generate chiral surface waves. The present design
provides homogeneous and superchiral fields of both handednesses over
arbitrarily large areas in a wide spectral range, resulting in the enhancement
of the circular dichroism signal by two orders of magnitude, thus paving the
road toward the successful combination of surface-enhanced spectroscopies and
electromagnetic superchirality.Comment: Added references. Corrected typos. Included new design for broadband
chiral surface wave
High-power collective charging of a solid-state quantum battery
Quantum information theorems state that it is possible to exploit collective
quantum resources to greatly enhance the charging power of quantum batteries
(QBs) made of many identical elementary units. We here present and solve a
model of a QB that can be engineered in solid-state architectures. It consists
of two-level systems coupled to a single photonic mode in a cavity. We
contrast this collective model ("Dicke QB"), whereby entanglement is genuinely
created by the common photonic mode, to the one in which each two-level system
is coupled to its own separate cavity mode ("Rabi QB"). By employing exact
diagonalization, we demonstrate the emergence of a quantum advantage in the
charging power of Dicke QBs, which scales like for .Comment: 8 pages, 5 figures. Version v2 supersedes version v1 where a
technical mistake was done in using the Holstein-Primakoff transformation.
The quantum advantage in the maximum charging power discussed in version v1
has been found to be robust. We have also updated the list of author
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