26,445 research outputs found
Low-Energy Lorentz Invariance in Lifshitz Nonlinear Sigma Models
This work is dedicated to the study of both large- and perturbative
quantum behaviors of Lifshitz nonlinear sigma models with dynamical critical
exponent in 2+1 dimensions. We discuss renormalization and
renormalization group aspects with emphasis on the possibility of emergence of
Lorentz invariance at low energies. Contrarily to the perturbative expansion,
where in general the Lorentz symmetry restoration is delicate and may depend on
stringent fine-tuning, our results provide a more favorable scenario in the
large- framework. We also consider supersymmetric extension in this
nonrelativistic situation.Comment: 28 pages, 4 figures, minor clarifications, typos corrected, published
versio
On Ward Identities in Lifshitz-like Field Theories
In this work, we develop a normal product algorithm suitable to the study of
anisotropic field theories in flat space, apply it to construct the symmetries
generators and describe how their possible anomalies may be found. In
particular, we discuss the dilatation anomaly in a scalar model with critical
exponent z=2 in six spatial dimensions.Comment: Clarifications adde
Constraining strangeness in dense matter with GW170817
Particles with strangeness content are predicted to populate dense matter,
modifying the equation of state of matter inside neutron stars as well as their
structure and evolution. In this work, we show how the modeling of strangeness
content in dense matter affects the properties of isolated neutrons stars and
the tidal deformation in binary systems. For describing nucleonic and hyperonic
stars we use the many-body forces model (MBF) at zero temperature, including
the mesons for the description of repulsive hyperon-hyperon
interactions. Hybrid stars are modeled using the MIT Bag Model with vector
interaction (vMIT) in both Gibbs and Maxwell constructions, for different
values of bag constant and vector interaction couplings. A parametrization with
a Maxwell construction, which gives rise to third family of compact stars (twin
stars), is also investigated. We calculate the tidal contribution that adds to
the post-Newtonian point-particle corrections, the associated love number for
sequences of stars of different composition (nucleonic, hyperonic, hybrid and
twin stars), and determine signatures of the phase transition on the
gravitational waves in the accumulated phase correction during the inspirals
among different scenarios for binary systems. On the light of the recent
results from GW170817 and the implications for the radius of
stars, our results show that hybrid stars can
only exist if a phase transition takes place at low densities close to
saturation
Theory of triangular lattice quasi-one-dimensional charge-transfer solids
Recent investigations of the magnetic properties and the discovery of
superconductivity in quasi-one-dimensional triangular lattice organic
charge-transfer solids have indicated the severe limitations of the effective
1/2-filled band Hubbard model for these and related systems. Our computational
studies of these materials within a 1/4-filled band Hubbard model in which the
organic monomer molecules, and not their dimers, constitute the sites of the
Hamiltonian are able to reproduce the experimental results. We ascribe the spin
gap transition in kappa-(BEDT-TTF)_2B(CN)_4 to the formation of a
two-dimensional paired-electron crystal and make the testable prediction that
the spin gap will be accompanied by charge-ordering and period doubling in two
directions. We find enhancement of the long-range component of superconducting
pairing correlations by the Hubbard repulsive interaction for band parameters
corresponding to kappa-(BEDT-TTF)_2CF_3SO_3. The overall results strongly
support a valence bond theory of superconductivity we have proposed recently.Comment: 8 pages, 7 figure
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