170 research outputs found
Quantum M^2 -> 2Lambda/3 discontinuity for massive gravity with a Lambda term
In a previous paper we showed that the absence of the van
Dam-Veltman-Zakharov discontinuity as M^2 -> 0 for massive spin-2 with a Lambda
term is an artifact of the tree approximation, and that the discontinuity
reappears at one loop, as a result of going from five degrees of freedom to
two. In this paper we show that a similar classical continuity but quantum
discontinuity arises in the "partially massless" limit M^2 -> 2Lambda/3, as a
result of going from five degrees of freedom to four.Comment: 8 pages, REVTe
Complementarity of the Maldacena and Karch-Randall Pictures
We perform a one-loop test of the holographic interpretation of the
Karch-Randall model, whereby a massive graviton appears on an AdS_4 brane in an
AdS_5 bulk. Within the AdS/CFT framework, we examine the quantum corrections to
the graviton propagator on the brane, and demonstrate that they induce a
graviton mass in exact agreement with the Karch-Randall result. Interestingly
enough, at one loop order, the spin 0, spin 1/2 and spin 1 loops contribute to
the dynamically generated (mass)^2 in the same 1: 3: 12 ratio as enters the
Weyl anomaly and the 1/r^3 corrections to the Newtonian gravitational
potential.Comment: 20 pages, Revtex 3, Discussion on the absence of a scalar ghost
clarified; Additional details on the computation give
Extended chiral algebras and the emergence of SU(2) quantum numbers in the Coulomb gas
We study a set of chiral symmetries contained in degenerate operators beyond
the `minimal' sector of the c(p,q) models. For the operators
h_{(2j+2)q-1,1}=h_{1,(2j+2)p-1} at conformal weight [ (j+1)p-1 ][ (j+1)q -1 ],
for every 2j \in N, we find 2j+1 chiral operators which have quantum numbers of
a spin j representation of SU(2). We give a free-field construction of these
operators which makes this structure explicit and allows their OPEs to be
calculated directly without any use of screening charges. The first non-trivial
chiral field in this series, at j=1/2, is a fermionic or para-fermionic
doublet. The three chiral bosonic fields, at j=1, generate a closed W-algebra
and we calculate the vacuum character of these triplet models.Comment: 23 pages Late
Encapsulation of gold nanostructures and oil-in-water nanocarriers in microgels with biomedical potential
IndexaciĂłn: Scopus.Funding: This research was funded by FONDECYT 1161450, 1150744, 11130494 and 1170929, FONDEQUIP EQM160157, EQM170111, CONICYT-FONDAP 15130011, and CONICYT PhD Scholarship 21141137.Here we report the incorporation of gold nanostructures (nanospheres or nanorods, functionalized with carboxylate-end PEG) and curcumin oil-in-water (O/W) nanoemulsions (CurNem) into alginate microgels using the dripping technique. While gold nanostructures are promising nanomaterials for photothermal therapy applications, CurNem possess important pharmacological activities as reported here. In this sense, we evaluated the effect of CurNem on cell viability of both cancerous and non-cancerous cell lines (AGS and HEK293T, respectively), demonstrating preferential toxicity in cancer cells and safety for the non-cancerous cells. After incorporating gold nanostructures and CurNem together into the microgels, microstructures with diameters of 220 and 540 ”m were obtained. When stimulating microgels with a laser, the plasmon effect promoted a significant rise in the temperature of the medium; the temperature increase was higher for those containing gold nanorods (11â12 ⊠C) than nanospheres (1â2 ⊠C). Interestingly, the incorporation of both nanosystems in the microgels maintains the photothermal properties of the gold nanostructures unmodified and retains with high efficiency the curcumin nanocarriers. We conclude that these results will be of interest to design hydrogel formulations with therapeutic applications. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/5/120
Hot String Soup
Above the Hagedorn energy density closed fundamental strings form a long
string phase. The dynamics of weakly interacting long strings is described by a
simple Boltzmann equation which can be solved explicitly for equilibrium
distributions. The average total number of long strings grows logarithmically
with total energy in the microcanonical ensemble. This is consistent with
calculations of the free single string density of states provided the
thermodynamic limit is carefully defined. If the theory contains open strings
the long string phase is suppressed.Comment: 13 pages, no figures, uses LaTex, some errors in equations have been
corrected, NSF-ITP-94-83, UCSBTH-94-3
Effects of La substitution on superconducting state of CeCoIn5
We report effects of La substitution on superconducting state of heavy
fermion superconductor CeCoIn5, as seen in transport and magnetization
measurements. As opposed to the case of conventional superconductors, pair
breaking by nonmagnetic La results in depression of Tc and indicates strong gap
anisotropy. Upper critical field Hc2 values decrease with increased La
concentration, but the critical field anisotropy, gamma=Hc2(a)/Hc2(c), does not
change in the Ce_{1-x}La_xCoIn5 (x=0-0.15). The electronic system is in the
clean limit for all values of x.Comment: Submitted to Phys. Rev.
Thermodynamic behavior of IIA string theory on a pp-wave
We obtain the thermal one loop free energy and the Hagedorn temperature of
IIA superstring theory on the pp-wave geometry which comes from the circle
compactification of the maximally supersymmetric eleven dimensional one. We use
both operator and path integral methods and find the complete agreement between
them in the free energy expression. In particular, the free energy in the limit is shown to be identical with that of IIB string theory on
maximally supersymmetric pp-wave, which indicates the universal thermal
behavior of strings in the large class of pp-wave backgrounds. We show that the
zero point energy and the modular properties of the free energy are naturally
incorporated into the path integral formalism.Comment: 25 pages, Latex, JHEP style, v4: revised for clarity without change
in main contents, version to appear in JHE
Fluxoid dynamics in superconducting thin film rings
We have measured the dynamics of individual magnetic fluxoids entering and
leaving photolithographically patterned thin film rings of the underdoped
high-temperature superconductor BiSrCaCuO, using a
variable sample temperature scanning SQUID microscope. These results can be
qualitatively described using a model in which the fluxoid number changes by
thermally activated nucleation of a Pearl vortex in, and transport of the Pearl
vortex across, the ring wall.Comment: 9 pages, 10 figures, fixed typo
Single-Brane Cosmological Solutions with a Stable Compact Extra Dimension
We consider 5-dimensional cosmological solutions of a single brane. The
correct cosmology on the brane, i.e., governed by the standard 4-dimensional
Friedmann equation, and stable compactification of the extra dimension is
guaranteed by the existence of a non-vanishing \hat{T}^5_5 which is
proportional to the 4-dimensional trace of the energy-momentum tensor. We show
that this component of the energy-momentum tensor arises from the backreaction
of the dilaton coupling to the brane. The same positive features are exhibited
in solutions found in the presence of non-vanishing cosmological constants both
on the brane (\Lambda_{br}) and in the bulk (\Lambda_B). Moreover, the
restoration of the Friedmann equation, with the correct sign, takes place for
both signs of so long as the sign of is opposite
in order to cancel the energy densities of the two cosmological
constants. We further extend our single-brane thin-wall solution to allow a
brane with finite thickness.Comment: 25 pages, Latex file, no figures, comments added, references updated,
final version to appear in Physical Review
Fluctuation induced hopping and spin polaron transport
We study the motion of free magnetic polarons in a paramagnetic background of
fluctuating local moments. The polaron can tunnel only to nearby regions of
local moments when these fluctuate into alignment. We propose this fluctuation
induced hopping as a new transport mechanism for the spin polaron. We calculate
the diffusion constant for fluctuation induced hopping from the rate at which
local moments fluctuate into alignment. The electrical resistivity is then
obtained via the Einstein relation. We suggest that the proposed transport
mechanism is relevant in the high temperature phase of the Mn pyrochlore
colossal magneto resistance compounds and Europium hexaboride.Comment: 8 pages, 3 figure
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