642 research outputs found
Colour-Flavour Locked Quark Stars in Light of the Compact Object in HESS J1731-347 and the GW190814 Event
The central compact object within HESS J1731- 347 possesses unique mass and
radius properties that renders it a compelling candidate for a self-bound star.
In this research, we examine the capability of quark stars composed of colour
superconducting quark matter to explain the latter object by using its
marginalised posterior distribution and imposing it as a constraint on the
relevant parameter space. Namely, we investigate quark matter for in
the colour superconducting phase, incorporating perturbative QCD corrections,
and we derive their properties accordingly. The utilised thermodynamic
potential of this work possesses an MIT bag model formalism with the parameters
being established as flavour-independent. In this instance, we conclude the
favour of 3-flavour over 2-flavour colour superconducting quark matter,
isolating our interest on the former. The parameter space is further confined
due to the additional requirement for a high maximum mass (), accounting for GW's secondary companion. We pay a
significant attention on the speed of sound and the trace anomaly (proposed as
a measure of conformality
[\href{https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.252702}{10.1103/PhysRevLett.129.252702}]).
We conclude that it is possible for colour-flavour locked quark stars to reach
high masses without violating the conformal bound or the if the quartic coefficient value does not
exceed an upper limit which is solely dependent on the established
. For , we find that the limit
reads . Lastly, a further study takes place on the
agreement of colour-flavour locked quark stars with additional astrophysical
objects including the GW and GW events, followed by a relevant
discussion.Comment: 13 pages, 10 figures, 1 tabl
The Electron Glass in a Switchable Mirror: Relaxation, Aging and Universality
The rare earth hydride YH can be tuned through the
metal-insulator transition both by changing and by illumination with
ultraviolet light. The transition is dominated by strong electron-electron
interactions, with transport in the insulator sensitive to both a Coulomb gap
and persistent quantum fluctuations. Via a systematic variation of UV
illumination time, photon flux, Coulomb gap depth, and temperature, we
demonstrate that polycrystalline YH serves as a model system for
studying the properties of the interacting electron glass. Prominent among its
features are logarithmic relaxation, aging, and universal scaling of the
conductivity
Reply to the Comment by B. Andresen
All the comments made by Andresen's comments are replied and are shown not to
be pertinent. The original discussions [ABE S., Europhys. Lett. 90 (2010)
50004] about the absence of nonextensive statistical mechanics with q-entropies
for classical continuous systems are reinforced.Comment: 5 pages. This is Reply to B. Andresen's Comment on the paper entitled
"Essential discreteness in generalized thermostatistics with non-logarithmic
entropy", Europhys. Lett. 90 (2010) 5000
De Sitter Cosmic Strings and Supersymmetry
We study massive spinor fields in the geometry of a straight cosmic string in
a de Sitter background. We find a hidden N=2 supersymmetry in the fermionic
solutions of the equations of motion. We connect the zero mode solutions to the
heat-kernel regularized Witten index of the supersymmetric algebra.Comment: Version similar to the one accepted by General Relativity and
Gravitatio
Kaluza-Klein Pistons with non-Commutative Extra Dimensions
We calculate the scalar Casimir energy and Casimir force for a
Kaluza-Klein piston setup in which the extra dimensional space contains a
non-commutative 2-sphere, . The cases to be studied are and respectively as extra dimensional spaces, with the
dimensional commutative torus. The validity of the results and the
regularization that the piston setup offers are examined in both cases. Finally
we examine the 1-loop corrected Casimir energy for one piston chamber, due to
the self interacting scalar field in the non-commutative geometry. The
computation is done within some approximations. We compare this case for the
same calculation done in Minkowski spacetime . A discussion on the
stabilization of the extra dimensional space within the piston setup follows at
the end of the article.Comment: 22 page
A Search for Correlation of Ultra-High Energy Cosmic Rays with IRAS-PSCz and 2MASS-6dF Galaxies
We study the arrival directions of 69 ultra-high energy cosmic rays (UHECRs)
observed at the Pierre Auger Observatory (PAO) with energies exceeding 55 EeV.
We investigate whether the UHECRs exhibit the anisotropy signal expected if the
primary particles are protons that originate in galaxies in the local universe,
or in sources correlated with these galaxies. We cross-correlate the UHECR
arrival directions with the positions of IRAS-PSCz and 2MASS-6dF galaxies
taking into account particle energy losses during propagation. This is the
first time that the 6dF survey is used in a search for the sources of UHECRs
and the first time that the PSCz survey is used with the full 69 PAO events.
The observed cross-correlation signal is larger for the PAO UHECRs than for 94%
(98%) of realisations from an isotropic distribution when cross-correlated with
the PSCz (6dF). On the other hand the observed cross-correlation signal is
lower than that expected from 85% of realisations, had the UHECRs originated in
galaxies in either survey. The observed cross-correlation signal does exceed
that expected by 50% of the realisations if the UHECRs are randomly deflected
by intervening magnetic fields by 5 degrees or more. We propose a new method of
analysing the expected anisotropy signal, by dividing the predicted UHECR
source distribution into equal predicted flux radial shells, which can help
localise and constrain the properties of UHECR sources. We find that the 69 PAO
events are consistent with isotropy in the nearest of three shells we define,
whereas there is weak evidence for correlation with the predicted source
distribution in the two more distant shells in which the galaxy distribution is
less anisotropic.Comment: 23 pages, version published in JCA
Wavefunctions and the Point of E8 in F-theory
In F-theory GUTs interactions between fields are typically localised at
points of enhanced symmetry in the internal dimensions implying that the
coefficient of the associated operator can be studied using a local
wavefunctions overlap calculation. Some F-theory SU(5) GUT theories may exhibit
a maximum symmetry enhancement at a point to E8, and in this case all the
operators of the theory can be associated to the same point. We take initial
steps towards the study of operators in such theories. We calculate
wavefunctions and their overlaps around a general point of enhancement and
establish constraints on the local form of the fluxes. We then apply the
general results to a simple model at a point of E8 enhancement and calculate
some example operators such as Yukawa couplings and dimension-five couplings
that can lead to proton decay.Comment: 46 page
The imprints of superstatistics in multiparticle production processes
We provide an update of the overview of imprints of Tsallis nonextensive
statistics seen in a multiparticle production processes. They reveal an
ubiquitous presence of power law distributions of different variables
characterized by the nonextensivity parameter q > 1. In nuclear collisions one
additionally observes a q-dependence of the multiplicity fluctuations
reflecting the finiteness of the hadronizing source. We present sum rules
connecting parameters q obtained from an analysis of different observables,
which allows us to combine different kinds of fluctuations seen in the data and
analyze an ensemble in which the energy (E), temperature (T) and multiplicity
(N) can all fluctuate. This results in a generalization of the so called
Lindhard's thermodynamic uncertainty relation. Finally, based on the example of
nucleus-nucleus collisions (treated as a quasi-superposition of nucleon-nucleon
collisions) we demonstrate that, for the standard Tsallis entropy with degree
of nonextensivity q < 1, the corresponding standard Tsallis distribution is
described by q' = 2 - q > 1.Comment: 12 pages, 3 figures. Based on invited talk given by Z.Wlodarczyk at
SigmaPhi2011 conference, Larnaka, Cyprus, 11-15 July 2011. To be published in
Cent. Eur. J. Phys. (2011
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