13 research outputs found
The volume of a soliton
There exists, in general, no unique definition of the size (volume, area, etc., depending on dimension) of a soliton. Here we demonstrate that the geometric volume (area etc.) of a soliton is singled out in the sense that it exactly coincides with the thermodynamical or continuum-mechanical volume. In addition, this volume may be defined uniquely for rather arbitrary solitons in arbitrary dimensions
HHL correlators, orbit averaging and form factors
We argue that the conventional method to calculate the OPE coefficients in
the strong coupling limit for heavy-heavy-light operators in the N=4
Super-Yang-Mills theory has to be modified by integrating the light vertex
operator not only over a single string worldsheet but also over the moduli
space of classical solutions corresponding to the heavy states. This reflects
the fact that we are primarily interested in energy eigenstates and not
coherent states. We tested our prescription for the BMN vacuum correlator, for
folded strings on and for two-particle states. Our prescription for
two-particle states with the dilaton leads to a volume dependence which matches
exactly to the structure of finite volume diagonal formfactors. As the volume
depence does not rely on the particular light operator we conjecture that
symmetric OPE coefficients can be described for any coupling by finite volume
diagonal form factors.Comment: 32 pages, 1 figure; v2: small corrections including signs, references
adde
Integrability and Dif feomorphisms on Target Space
We briefly review the concepts of generalized zero curvature conditions and integrability in higher dimensions, where integrability in this context is related to the existence
of infinitely many conservation laws. Under certain assumptions, it turns out that these
conservation laws are, in fact, generated by a class of geometric target space transformations, namely the volume-preserving dif feomorphisms. We classify the possible conservation
laws of field theories for the case of a three-dimensional target space. Further, we discuss
some explicit examplesA.W. gratefully acknowledges support from Adam Krzyzanowski Fund and Jagiellonian University (grant WRBW 41/07). C.A. and J.S.-G. thank MCyT (Spain) and FEDER (FPA2005-
01963), and support from Xunta de Galicia (grant PGIDIT06PXIB296182PR and Conselleria
de Educacion). Further, C.A. acknowledges support from the Austrian START award project
FWF-Y-137-TEC and from the FWF project P161 05 NO 5 of N.J. MauserS
Quasi-universal relations for generalized Skyrme stars
First proposed in 2013 by Yagi and Yunes, the quasi-universal \emph{I-Love-Q
relations} consist of a set of relations between the moment of inertia, the
spin-induced quadrupole moment and the electric quadrupolar tidal deformability
of neutron stars which are independent of the Equation of State (EoS) within an
accuracy of . In this work, we show that these relations hold for
different Skyrme-based nuclear matter EoS and also for the star-like solutions
of different Einstein-BPS-Skyrme-models, some of which do not even present a
barotropic equation of state. Further, other quasi-universal relations are
analyzed, and together with recent GW observations, we use them to select the
generalized Skyrme model that better reproduces observations. Our results
reaffirm both the universality of the \emph{I-Love-Q} relations and the
suitability of generalized Skyrme models to describe nuclear matter inside
neutron stars.Comment: 23 pages, 11 figure
Kaon condensation in skyrmion matter and compact stars
We address the possibility of the appearance of a charged kaon condensate in
neutron star cores described within a generalized Skyrme model. Our treatment
of strange degrees of freedom is based on the Bound State Approach by Callan
and Klebanov, which allows to obtain an in-medium effective potential for the
-wave kaon condensate. We predict the onset of kaon condensation at a
certain threshold density - whose value depends on the parameters of the model,
and ranges between 1.5 and 2.5 times saturation density -, and obtain both the
particle fractions and equation of state for dense matter in the kaon condensed
phase. Finally, we discuss the effect of such condensates on the mass-radius
curves and other observable properties of neutron stars with kaon condensed
cores.Comment: 17 pages, 8 figure
Dense matter equation of state and phase transitions from a Generalized Skyrme model
Skyrmion crystals are the field configurations which minimize the energy per
baryon in the infinitely large topological charge sector of the Skyrme model,
at least for sufficiently high density. They are, therefore, an important tool
to describe the ground state of cold, symmetric nuclear matter at high density
regimes. In this work, we analyze different crystalline phases and the
existence of phase transitions between them within the generalized Skyrme
model, with the ultimate goal of describing symmetric nuclear matter in a wide
regime of densities. Furthermore, we propose a new energy-minimizing phase for
densities lower than the nuclear saturation point () which also presents a
good qualitative behavior in the zero density limit, thereby improving the
description of strongly interacting matter in the region .Comment: 16 pages, 10 figures; v2: presentation slightly improved, some
references adde
Topological phase transitions in the gauged BPS baby Skyrme model
We demonstrate that the gauged BPS baby Skyrme model with a double
vacuum potential allows for phase transitions from a non-solitonic to a solitonic phase,
where the latter corresponds to a ferromagnetic liquid. Such a transition can be generated
by increasing the external pressure P or by turning on an external magnetic field H.
As a consequence, the topological phase where gauged BPS baby skyrmions exist, is a
higher density phase. For smaller densities, obtained for smaller values of P and H, a
phase without solitons is reached. We find the critical line in the P,H parameter space.
Furthermore, in the soliton phase, we find the equation of state for the baby skyrmion
matter V = V (P,H) at zero temperature, where V is the “volume”, i.e., area of the
solitonsThe authors acknowledge financial support from the Ministry of Education, Culture,
and Sports, Spain (Grant No. FPA2011-22776), the Xunta de Galicia (Grant No. INCITE09.296.035PR
and Conselleria de Educacion), the Spanish Consolider-Ingenio 2010
Programme CPAN (CSD2007-00042), and FEDER. Further, the authors acknowledge support
from the Polish FOCUS grant (No. 42/F/AW/2014). CN thanks the Spanish Ministery
of Education, Culture and Sports for financial support (grant FPU AP2010-5772)S
A new consistent Neutron Star Equation of State from a Generalized Skyrme model
We propose a new equation of state for nuclear matter based on a generalized
Skyrme model which is consistent with all current constraints on the observed
properties of neutron stars. This generalized model depends only on two free
parameters related to the ranges of pressure values at which different
submodels are dominant, and which can be adjusted so that mass-radius and
deformability constraints from astrophysical and gravitational wave
measurements can be met. Our results support the Skyrme model and its
generalizations as good candidates for a low energy effective field-theoretic
description of nuclear matter even at extreme conditions such as those inside
neutron stars.Comment: 8 pages, 3 figures. Minor typos fixed. Version accepted for
publication in Phys. Lett.
Universal relations for rotating Boson Stars
Boson stars represent a hypothetical exotic type of compact stellar object
that may be observed from the gravitational signal of coalescing binaries in
current and future GW detectors. In this work we show that the moment of
inertia , the (dimensionless) angular momentum and the quadrupole
moment of rotating boson stars obey a universal relation, valid for a wide
set of boson star models. Further, the obtained relation clearly
differs from its famous neutron star counterpart, providing us with an
unequivocal diagnostic tool to distinguish boson stars from ordinary compact
stars or other celestial bodies in GW observations. Such universal (i.e.
model-independent) relations also provide a useful tool to probe the strong
gravity regime of general relativity and to constrain the equation of state of
matter inside compact stars.Comment: 7 pages, 4 figures. In this current version, we have corrected a typo
in eq.17 and also changed the table of coefficients, and figures [2],[3], and
[4] where we had a normalization numerical issue that now is fixe
Correlation functions of three heavy operators - the AdS contribution
We consider operators in N=4 SYM theory which are dual, at strong coupling,
to classical strings rotating in S^5. Three point correlation functions of such
operators factorize into a universal contribution coming from the AdS part of
the string sigma model and a state-dependent S^5 contribution. Consequently a
similar factorization arises for the OPE coefficients. In this paper we
evaluate the AdS universal factor of the OPE coefficients which is explicitly
expressed just in terms of the anomalous dimensions of the three operators.Comment: 49 pages, 3 figures; v.2 references corrected; v3: corrected
discussion in section 5, results unchange