arXiv subjects

V. de la Incera

Publications and source records attributed to V. de la Incera.

At least 19 recordsLinked to original sources

arXiv2024

Thermal phonon fluctuations and stability of the magnetic dual chiral density wave phase in dense QCD

We study the stability against thermal phonon fluctuations of the magnetic dual chiral density wave (MDCDW) phase, an inhomogeneous phase arising in cold dense QCD in a magnetic field. Following a recent study that demonstrated the absence of the Landau-Peierls (LP) instability from this phase, we calculate the (threshold) temperature at which the phonon fluctuations wash out the long-range order over a range of magnetic fields and densities relevant to astrophysical applications. Using a high-order Ginzburg-Landau expansion, we find that the threshold temperature is very near the critical temperature for fields of order $10^{18}$ G, and still a sizable fraction of the critical temperature for fields of order $10^{17}$ G. Therefore, at sufficiently large magnetic fields, the long-range order of the MDCDW phase is preserved over most of the parameter space where it is energetically favored; at smaller magnetic fields, the long-range order is still preserved over a considerable region of parameter space relevant to compact stars. We provide general symmetry arguments to explain why a magnetic field alone is not enough to eliminate the LP instability that characterizes single-modulated phases in 3+1 dimensions.

nucl-th↗

arXiv2024

Axion-Polaritons in quark stars: a possible solution to the missing pulsar problem

This paper proposes an alternative mechanism to solve the so-called missing pulsar problem, a standing paradox between the theoretical expectations about the number of pulsars that should exist in the galaxy center of the Milky Way and their absence in the observations. The mechanism is based on the transformation of incident $γ$ rays into hybridized modes, known as axion-polaritons, which can exist inside highly magnetized quark stars with a quark matter phase known as the magnetic dual chiral density wave phase. This phase, which is favored over several other dense matter phases candidates at densities a few times nuclear saturation density, has already passed several important astrophysical tests. In the proposed mechanism, the absence of young magnetars occurs because as electromagnetic waves inside the star can only propagate through the hybridized modes, incident photons coming from a $γ$-ray burst get transformed into massless and massive axion polaritons by the Primakoff effect. Once thermalized, the massive axion-polaritons can self-gravitate up to a situation where their total mass overpasses the Chandrasekhar limit for these bosons, producing a mini blackhole that collapses the star.

nucl-th↗

arXiv2022

Magnetic Dual Chiral Density Wave: A Candidate Quark Matter Phase for the Interior of Neutron Stars

In this review, we discuss the physical characteristics of the magnetic dual chiral density wave (MDCDW) phase of dense quark matter and argued why it is a promising candidate for the interior matter phase of neutron stars. The MDCDW condensate occurs in the presence of a magnetic field. It is a single-modulated chiral density wave characterized by two dynamically generated parameters: the fermion quasiparticle mass $m$ and the condensate spatial modulation $q$. The lowest Landau level quasiparticle modes in the MDCDW system are asymmetric about the zero energy, a fact that leads to the topological properties and anomalous electric transport exhibited by this phase. The topology makes the MDCDW phase robust against thermal phonon fluctuations, and as such, it does not display the Landau-Peierls instability, a stapled feature of single-modulated inhomogeneous chiral condensates in three dimensions. The topology is also reflected in the presence of the electromagnetic chiral anomaly in the effective action and in the formation of hybridized propagating modes known as an axion-polaritons. Taking into account that one of the axion-polaritons of this quark phase is gapped, we argued how incident $γ$-ray photons can be converted into gapped axion-polaritons in the interior of a magnetar star in the MDCDW phase leading the star to collapse, a phenomenon that can serve to explain the so-called missing pulsar problem in the galactic center.

hep-ph↗

arXiv2021

Quark matter contribution to the heat capacity of magnetized neutron stars

In this paper, we find the heat capacity of the magnetic dual chiral density wave (MDCDW) phase of dense quark matter and use it to explore the feasibility of this phase for a neutron star interior. MDCDW is a spatially inhomogeneous phase of quark matter known to be favored at intermediate densities over the chirally symmetric phase and the color-flavor-locked superconducting phase. By comparing our result to the lower limit of the core heat capacity established from observations of transiently accreting neutron stars, we show that the heat capacity of MDCDW quark matter is well above that lower limit and hence cannot be ruled out. This result adds to a wealth of complementary investigations, all of which has served to strengthen the viability of a neutron star interior made of MDCDW quark matter. For completeness, we review the contributions to the heat capacity of the main neutron star ingredients at low, high and intermediate densities, with and without the presence of a magnetic field.

nucl-th↗

arXiv2018

Novel Topological Effects in Dense QCD in a Magnetic Field

We study the electromagnetic properties of dense QCD in the so-called Magnetic Dual Chiral Density Wave phase. This inhomogeneous phase exhibits a nontrivial topology that comes from the fermion sector due to the asymmetry of the lowest Landau level modes. The nontrivial topology manifests in the electromagnetic effective action via a chiral anomaly term $~θF^{μν}\tilde{F}_{μν}$, with a dynamic axion field $θ$ given by the phase of the dual chiral density wave condensate. The coupling of the axion with the electromagnetic field leads to several macroscopic effects that include, among others, an anomalous, nondissipative Hall current, an anomalous electric charge, magnetoelectricity, and the formation of a hybridized propagating mode known as an axion polariton. Connection to topological insulators and Weyls semimetals, as well as possible implications for heavy-ion collisions and neutron stars are all highlighted.

nucl-th↗

arXiv2017

Dissipationless Hall Current in Dense Quark Matter in a Magnetic Field

We show the realization of axion electrodynamics within the Dual Chiral Density Wave phase of dense quark matter in the presence of a magnetic field. The system exhibits an anomalous dissipantionless Hall current perpendicular to the magnetic field and an anomalous electric charge density. Connection to topological insulators and 3D optical lattices, as well as possible implications for heavy-ion collisions and neutron stars are outlined.

nucl-th↗

arXiv2016

Exploring Dense and Cold QCD in Magnetic Fields

Strong magnetic fields are commonly generated in off-central relativistic heavy-ion collisions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab and in the Large Hadron Collider at CERN and have been used to probe the topological configurations of the QCD vacua. A strong magnetic field can affect the character and location of the QCD critical point, influence the QCD phases, and lead to anomalous transport of charge. To take advantage of the magnetic field as a probe of QCD at higher baryon densities, we are going to need experiments capable to scan the lower energy region. In this context, the nuclotron-based ion collider facility (NICA) at JINR offers a unique opportunity to explore such a region and complement alternative programs at RHIC and other facilities. In this paper we discuss some relevant problems of the interplay between QCD and magnetic fields and the important role the experiments at NICA can play in tackling them.

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arXiv2015

Crystalline chiral condensates as a component of compact stars

We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a magnetic field background on the equation of state for compact stellar objects. After building a hybrid star composed of nuclear and quark matter using the Maxwell construction, we find, by solving the Tolman-Oppenheimer-Volkoff equations for stellar equilibrium, that our equation of state supports stars with masses around 2 $M_\odot$ for values of the magnetic field that are in accordance with those inferred from magnetar data. The inclusion of a weak vector interaction term in the quark part allows one to reach 2 solar masses for relatively small central magnetic fields, making this composition a viable possibility for describing the internal degrees of freedom of this class of astrophysical objects.

nucl-th↗

arXiv2015

Gluon effects on the equation of state of color superconducting strange stars

Compact astrophysical objects are a window for the study of strongly interacting nuclear matter given the conditions in their interiors, which are not reproduced in a laboratory environment. Much has been debated about their composition with possibilities ranging from a simple mixture of mostly protons and neutrons to deconfined quark matter. Recent observations on the mass of two pulsars, PSR J1614-2230 and PSR J0348+0432, have posed a great restriction on their composition, since the equation of state must be hard enough to support masses of about at least two solar masses. The onset of quarks tends to soften the equation of state, but it can get substantially stiffer since in the high-dense medium a repulsive vector interaction channel is opened. Nevertheless, we show that once gluon effects are considered, the equation of state of quark matter in the color-flavor-locked phase of color superconductivity becomes softer decreasing the maximum stellar mass that can be reached when not considering their influence. This may indicate that stars made entirely of color superconducting matter can only be favored to describe compact stars if the repulsive vector constant is high enough.

hep-ph↗

arXiv2015

Quark Antiscreening at Strong Magnetic Field and Inverse Magnetic Catalysis

The dependence of the QCD coupling constant with a strong magnetic field and the implications for the critical temperature of the chiral phase transition are investigated. It is found that the coupling constant becomes anisotropic in a strong magnetic field and that the quarks, confined by the field to the lowest Landau level where they pair with antiquarks, produce an antiscreening effect. These results lead to inverse magnetic catalysis, providing a natural explanation for the behavior of the critical temperature in the strong-field region.

nucl-th↗

arXiv2013

Superconducting phases of strange quark matter in the NJL model

We analyze the color-flavor-locked phase of strange quark matter modelled by the three-flavor Nambu-Jona-Lasinio (NJL) framework with and without magnetic field and discuss some additional constraints on the stability scenario when a high magnetic field is applied. We compare the results obtained by employing the MIT Bag Model and discuss the pairing gap behavior and its influence on the equation of state.

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arXiv2004

Photons and Fermions in Spacetime with a Compactified Spatial Dimension

The effects of a nonsimply connected spacetime with the topology of $S^{1}\times R^{3}$ in the vacua of QED and gauged-NJL theories are investigated. It is shown that the polarization effects of twisted and untwisted fermions in QED are equivalent, once the corresponding stable vacuum solution of each fermion class is taken into account. The photon propagation in QED is found to be anisotropic and characterized by several massive photon modes and a superluminal transverse mode. At small compactification radius the masses of the massive modes increase as the inverse of the radius, while the massless photon mode has a superluminal velocity that increases logarithmically with that distance. At low energies the photon masses lead to an effective confinement of the gauge fields into a $(2+1)-$dimensional manifold transverse to the compactified direction. In the gauged-NJL model, it is shown that for both twisted and untwisted fermions, the smaller the compactification radius, the larger the critical four-fermion coupling needed to generate a fermion-antifermion chiral symmetry breaking condensate.

hep-ph↗

arXiv2004

Neutrino Propagation in a Strongly Magnetized Medium

We derive general expressions at the one-loop level for the coefficients of the covariant structure of the neutrino self-energy in the presence of a constant magnetic field. The neutrino energy spectrum and index of refraction are obtained for neutral and charged media in the strong-field limit ($M_{W}\gg \sqrt{B}\gg m_{e},T,μ,| \mathbf{p}| $) using the lowest Landau level approximation. The results found within the lowest Landau level approximation are numerically validated, summing in all Landau levels, for strong $B\gg T^{2}$ and weakly-strong $B \gtrsim T^{2}$ fields. The neutrino energy in leading order of the Fermi coupling constant is expressed as the sum of three terms: a kinetic-energy term, a term of interaction between the magnetic field and an induced neutrino magnetic moment, and a rest-energy term. The leading radiative correction to the kinetic-energy term depends linearly on the magnetic field strength and is independent of the chemical potential. The other two terms are only present in a charged medium. For strong and weakly-strong fields, it is found that the field-dependent correction to the neutrino energy in a neutral medium is much larger than the thermal one. Possible applications to cosmology and astrophysics are considered.

hep-ph↗

arXiv2003

Beyond-Constant-Mass-Approximation Magnetic Catalysis in the Gauge Higgs-Yukawa Model

Beyond-constant-mass approximation solutions for magnetically catalyzed fermion and scalar masses are found in a gauge Higgs-Yukawa theory in the presence of a constant magnetic field. The obtained fermion masses are several orders of magnitude larger than those found in the absence of Yukawa interactions. The masses obtained within the beyond-constant-mass approximation exactly reduce to the results within the constant-mass approach when the condition $ν\ln (\frac{1}{\hat{m}^{2}})\ll 1$ is satisfied. Possible applications to early universe physics and condensed matter are discussed.

hep-ph↗

arXiv2002

Hypermagnetic Field Effects in the Thermal Bath of Chiral Fermions

The dispersion relations for leptons in the symmetric phase of the electroweak model in the presence of a constant hypermagnetic field are investigated. The one-loop fermion self-energies are calculated in the lowest Landau level approximation and used to show that the hypermagnetic field forbids the generation of the ''effective mass'' found as a pole of the fermions' propagators at high temperature and zero fields. In the considered approximation leptons behave as massless particles propagating only along the direction of the external field. The reported results can be of interest for the cosmological implications of primordial hypermagnetic fields.

hep-ph↗

arXiv2002

Thermal Conductivity in 3D NJL Model Under External Magnetic Field

The thermal conductivity of the (2+1)-dimensional NJL model in the presence of a constant magnetic field is calculated in the mean-field approximation and its different asymptotic regimes are analyzed. Taking into account the dynamical generation of a fermion mass due to the magnetic catalysis phenomenon, it is shown that for certain relations among the theory's parameters (particle width, temperature and magnetic field), the profile of the thermal conductivity versus the applied field exhibits kink- and plateau-like behaviors. We point out possible applications to planar condensed matter.

cond-mat.supr-con↗

arXiv2002

Magnetic Field Induced Gap and Kink Behavior of Thermal Conductivity

The thermal conductivity of a quasiparticle (QP) system described by a relativistic four-fermion interaction model in the presence of an external magnetic field is calculated. It is shown that, for narrow width of quasiparticles, the thermal conductivity, as a function of the applied magnetic field, exhibits a kink behavior at a critical field $B_{c}\sim T^{2}$. The kink is due to the opening of a gap in the QP spectrum at a critical magnetic field $B_c$ and to the enhancement of the transitions between the zeroth and first Landau levels. Possible applications of the results are discussed.

hep-ph↗

arXiv2002

Neutrino Self-Energy and Index of Refraction in Strong Magnetic Field: A New Approach

The Ritus' $E_{p}$ eigenfunction method is extended to the case of spin-1 charged particles in a constant electromagnetic field and used to calculate the one-loop neutrino self-energy in the presence of a strong magnetic field.From the obtained self-energy, the neutrino dispersion relation and index of refraction in the magnetized vacuum are determined within the field range $m_{e}^{2}\ll eB\ll M_{W}^{2}$. The propagation of neutrinos in the magnetized vacuum is anisotropic due to the dependence of the index of refraction on the angle between the directions of the neutrino momentum and the external field. Possible cosmological implications of the results are discussed.

hep-ph↗