The boundary effects in the screening of an applied magnetic field in a charged anyon fluid at fi... more The boundary effects in the screening of an applied magnetic field in a charged anyon fluid at finite density (µ = 0) and temperature (T = 0) are investigated. By analytically solving the extremum equations of the system and minimizing the free energy density, we find that in a sample with only one boundary (the half plane), a total Meissner effect takes place; while the sample with two boundaries (the infinite strip) exhibits a partial Meissner effect. The short-range modes of propagation of the magnetic field inside the fluid are characterized by two temperature dependent penetration lengths.
The screening of an applied magnetic field in a charged anyon fluid at finite density (μ≠0) and t... more The screening of an applied magnetic field in a charged anyon fluid at finite density (μ≠0) and temperature (T≠0) is investigated. Using the semi-infinite sample boundary conditions we find, at densities typical of high-temperature superconducting materials, that the anyon fluid exhibits a superconducting behavior. The total Meissner screening is characterized by two penetration lengths, corresponding to two short-range eigenmodes of propagation within the anyon fluid.
In this paper, we find the heat capacity of the magnetic dual chiral density wave (MDCDW) phase o... more 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.
It is well known that for a fermion system with an isotropic equation of state (EOS), the square ... more It is well known that for a fermion system with an isotropic equation of state (EOS), the square of the speed of sound (SOS) 2 is a measure of the stiffness of the equation of state (EOS). It is also known that in the presence of a magnetic field the EOS becomes anisotropic with two different pressures arising, one directed parallel to the field direction and one perpendicular to it. Since the SOS in a medium is created by pressure oscillations, the anisotropy in the pressure should be transferred to the SOS. In this paper, we derive from first principles the anisotropic wavelike equation from where the expressions for the longitudinal and transverse SOS in the presence of a uniform magnetic field can be obtained. We also investigate the degree to which the magnetic field in the weak and the strong limit affects the two SOS of (i) a system of hadrons modeled by the nonlinear Walecka model and (ii) a system of quarks modeled by the MIT bag model. We find that for the systems considered, the effects of the magnetic field on the SOS anisotropy are mild up to 10 18 G. Links to neutrons star physics are discussed throughout the paper.
We investigate the effects of a magnetic field on the thermodynamics of a neutron system at finit... more We investigate the effects of a magnetic field on the thermodynamics of a neutron system at finite density and temperature. Our main motivation is to deepen the understanding of the physics of a class of neutron stars known as magnetars, which exhibit extremely strong magnetic fields. Taking into account two facts: (i) the existence of a pressure anisotropy in the presence of a magnetic field and (ii) that the quantum field theory contribution to the pressure is non-negligible, we show that the maximum value that the inner magnetic field of a star can reach while being in agreement with the magneto-hydrostatic equilibrium between the gravitational and matter pressures becomes 10 17 G, an order of magnitude smaller than the previous value obtained through the scalar virial theorem; that the magnetic field has a negligible effect on the neutron system's equation of state; that the system's magnetic susceptibility increases with the temperature and that the specific heat CV does not significantly change with the magnetic field in the range of temperatures characteristic of proto neutron stars.
We explore the inhomogeneous QCD phases at finite density and temperature using a (3+1)dimensiona... more We explore the inhomogeneous QCD phases at finite density and temperature using a (3+1)dimensional Nambu-Jona-Lasinio (NJL) model in the large Nc limit with an additional attractive tensor-tensor interaction channel. For single modulated solutions, the problem reduces to solving the gap equation of a Chiral Gross-Neveu (N JL2) theory, whose minimum solution is a periodic array of chirally twisted kinks. At zero temperature, the minimum solution reduces to the quarkyonic chiral spiral found in quarkyonic matter. The connection between the quarkyonic matter and our (3+1)-dimensional NJL model is rooted on the fact that the first reduces to (1+1)-dimensional QCD and the second to the N JL2 theory, both of which have continuous chiral symmetry and asymptotic freedom. Our findings can be useful to obtain a reliable qualitative picture of the QCD phase diagram and the location of the QCD critical point in the technically challenging region of intermediate densities and temperatures.
In this review, we discuss the physical characteristics of the magnetic dual chiral density wave ... more In this review, we discuss the physical characteristics of the magnetic dual chiral density wave (MDCDW) phase of dense quark matter and argue 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 staple 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 ...
We investigate the stability of the Magnetic Dual Chiral Density Wave (MD-CDW) phase of cold and ... more We investigate the stability of the Magnetic Dual Chiral Density Wave (MD-CDW) phase of cold and dense QCD against collective low-energy fluctuations of the order parameter. The appearance of additional structures in the system free-energy due to the explicit breaking of the rotational and isospin symmetries by the external magnetic field and the field-induced asymmetry of the lowest Landau level modes play a crucial role in the analysis. The new structures not only affect the condensate minimum equations, but also the spectrum of the thermal fluctuations, which lacks the transverse soft modes that typically affect single-modulated inhomogeneous phases in the absence of a magnetic field. Consequently, the long-range order of the MDCDW phase is preserved at finite temperature. The lack of Landau-Peierls instabilities in the MDCDW phase makes this inhomogeneous phase of dense quark matter particularly relevant for the physics of neutron stars.
Proceedings of XXXIV edition of the Brazilian Workshop on Nuclear Physics — PoS(XXXIV BWNP), 2012
In this talk I review some of the main findings on magnetism in color superconductivity. The phys... more In this talk I review some of the main findings on magnetism in color superconductivity. The physical characteristic of the different phases that are reached by increasing the applied magnetic field in a three-flavor color superconductor at asymptotically high densities are discussed. A mechanism to boost a seed magnetic field in high-dense quark matter is presented. Also, it is shown how a magnetic field can be generated in a color superconductor at moderate densities. Possible implications of these results for the astrophysics of magnetized compact objects are indicated.
The chiral symmetry breaking in a Nambu-Jona-Lasinio effective model of quarks in the presence of... more The chiral symmetry breaking in a Nambu-Jona-Lasinio effective model of quarks in the presence of a magnetic field is investigated. We show that new interaction tensor channels open up via Fierz identities due to the explicit breaking of the rotational symmetry by the magnetic field. We demonstrate that the magnetic catalysis of chiral symmetry breaking leads to the generation of two independent condensates, the conventional chiral condensate and a spin-one condensate. While the chiral condensate generates, as usual, a dynamical fermion mass, the new condensate enters as a dynamical anomalous magnetic moment in the dispersion of the quasiparticles. Since the pair, formed by a quark and an antiquark with opposite spins, possesses a resultant magnetic moment, an external magnetic field can align it giving rise to a net magnetic moment for the ground state. The two condensates contribute to the effective mass of the LLL quasiparticles in such a way that the critical temperature for chiral symmetry restoration becomes enhanced.
Our Universe is full of regions where extreme physical conditions are realized. A most intriguing... more Our Universe is full of regions where extreme physical conditions are realized. A most intriguing case is the super-dense core of neutron stars, some of which also have super-strong magnetic fields, hence called magnetars. In this paper we review the current understanding of the physical properties of the different phases of quark matter at very high densities in the presence of large magnetic fields. We also discuss how the Meissner instability produced at moderate densities by a pairing stress due to the medium neutrality and β -equilibrium constraints can lead to the spontaneous generation of a magnetic field.
In this work we study the dynamical generation of a fermion mass induced by a constant and unifor... more In this work we study the dynamical generation of a fermion mass induced by a constant and uniform external magnetic field in an Abelian gauge model with a Yukawa term. We show that the Yukawa coupling not only enhances the dynamical generation of the mass, but it substantially decreases the magnetic field required for the mass to be generated at temperatures comparable to the electroweak critical temperature. These results indicate that if large enough primordial magnetic fields were present during the early universe evolution, the field-induced generation of fermion masses, which in turn corresponds to the generation of fermion bound states, may play an important role in the electroweak phase transition.
We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a... more 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 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 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.
Bulk and shear viscosity coefficients for systems composed of quasiparticles with medium-modified... more Bulk and shear viscosity coefficients for systems composed of quasiparticles with medium-modified dispersion relations are determined within an effective kinetic theory approach of Boltzmann-Vlasov type. Local conservation of energy and momentum, which is self-consistently embedded in the kinetic theory, implies in thermal equilibrium thermodynamic consistency in quasiparticle approaches.
This paper summarizes some of the recent results on magnetism in high dense mediums, where the ph... more This paper summarizes some of the recent results on magnetism in high dense mediums, where the phenomenon of color superconductivity can be present, and its possible implications for the astrophysics of compact objects. The presentation will be organized through the answers to three fundamental questions.
We investigate the equation of state (EoS) along the BCS-BEC crossover for a quark system describ... more We investigate the equation of state (EoS) along the BCS-BEC crossover for a quark system described by a Nambu-Jona-Lasinio model with multi-fermion interactions. Together with attractive channels for particle-antiparticle (GS) and particle-particle (GD) interactions, a multi-fermion channel with coupling λ that accounts for the diquark-diquark repulsion is also considered. The chiral and diquark condensates are found in the mean-field approximation for different values of the coupling constants. The parameter values where the BCS-BEC crossover can take place are found, and the EoS is used to identify the stability region where the BEC regime has positive pressure. We discuss how the particle density and the repulsive diquark-diquark interaction affect the stability window in the GS − GD plane and find the profile of the pressure versus the density for various values of λ and GD. The effects of λ and GD in the BCS-BEC crossover tend to compensate each other, allowing for a feasible region of densities where the crossover can occur with positive pressure. These results, although mainly qualitative, should serve as a preliminary step in the microscopic analysis required to determine the feasibility of the BCS-BEC crossover and its realization in more realistic models of dense QCD that can be relevant for applications to neutron stars.
Strongly Interacting Matter in Magnetic Fields, 2013
We review the mechanisms via which an external magnetic field can affect the ground state of cold... more We review the mechanisms via which an external magnetic field can affect the ground state of cold and dense quark matter. In the absence of a magnetic field, at asymptotically high densities, cold quark matter is in the Color-Flavor-Locked (CFL) phase of color superconductivity characterized by three scales: the superconducting gap, the gluon Meissner mass, and the baryonic chemical potential. When an applied magnetic field becomes comparable with each of these scales, new phases and/or condensates may emerge. They include the magnetic CFL (MCFL) phase that becomes relevant for fields of the order of the gap scale; the paramagnetic CFL, important when the field is of the order of the Meissner mass, and a spin-one condensate associated to the magnetic moment of the Cooper pairs, significant at fields of the order of the chemical potential. We discuss the equation of state (EoS) of MCFL matter for a large range of field values and consider possible applications of the magnetic effects on dense quark matter to the astrophysics of compact stars.
Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of pair... more Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of paired quark matter in a magnetic field, and taking into consideration the separation between the longitudinal and transverse pressures due to the field-induced breaking of the spatial rotational symmetry, the equation of state (EoS) of the MCFL phase is self-consistently determined. This result is then used to investigate the possibility of absolute stability, which turns out to require a field-dependent "bag constant" to hold. That is, only if the bag constant varies with the magnetic field, there exists a window in the magnetic field vs. bag constant plane for absolute stability of strange matter. Implications for stellar models of magnetized (self-bound) strange stars and hybrid (MCFL core) stars are calculated and discussed.
The boundary effects in the screening of an applied magnetic field in a charged anyon fluid at fi... more The boundary effects in the screening of an applied magnetic field in a charged anyon fluid at finite density (µ = 0) and temperature (T = 0) are investigated. By analytically solving the extremum equations of the system and minimizing the free energy density, we find that in a sample with only one boundary (the half plane), a total Meissner effect takes place; while the sample with two boundaries (the infinite strip) exhibits a partial Meissner effect. The short-range modes of propagation of the magnetic field inside the fluid are characterized by two temperature dependent penetration lengths.
The screening of an applied magnetic field in a charged anyon fluid at finite density (μ≠0) and t... more The screening of an applied magnetic field in a charged anyon fluid at finite density (μ≠0) and temperature (T≠0) is investigated. Using the semi-infinite sample boundary conditions we find, at densities typical of high-temperature superconducting materials, that the anyon fluid exhibits a superconducting behavior. The total Meissner screening is characterized by two penetration lengths, corresponding to two short-range eigenmodes of propagation within the anyon fluid.
In this paper, we find the heat capacity of the magnetic dual chiral density wave (MDCDW) phase o... more 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.
It is well known that for a fermion system with an isotropic equation of state (EOS), the square ... more It is well known that for a fermion system with an isotropic equation of state (EOS), the square of the speed of sound (SOS) 2 is a measure of the stiffness of the equation of state (EOS). It is also known that in the presence of a magnetic field the EOS becomes anisotropic with two different pressures arising, one directed parallel to the field direction and one perpendicular to it. Since the SOS in a medium is created by pressure oscillations, the anisotropy in the pressure should be transferred to the SOS. In this paper, we derive from first principles the anisotropic wavelike equation from where the expressions for the longitudinal and transverse SOS in the presence of a uniform magnetic field can be obtained. We also investigate the degree to which the magnetic field in the weak and the strong limit affects the two SOS of (i) a system of hadrons modeled by the nonlinear Walecka model and (ii) a system of quarks modeled by the MIT bag model. We find that for the systems considered, the effects of the magnetic field on the SOS anisotropy are mild up to 10 18 G. Links to neutrons star physics are discussed throughout the paper.
We investigate the effects of a magnetic field on the thermodynamics of a neutron system at finit... more We investigate the effects of a magnetic field on the thermodynamics of a neutron system at finite density and temperature. Our main motivation is to deepen the understanding of the physics of a class of neutron stars known as magnetars, which exhibit extremely strong magnetic fields. Taking into account two facts: (i) the existence of a pressure anisotropy in the presence of a magnetic field and (ii) that the quantum field theory contribution to the pressure is non-negligible, we show that the maximum value that the inner magnetic field of a star can reach while being in agreement with the magneto-hydrostatic equilibrium between the gravitational and matter pressures becomes 10 17 G, an order of magnitude smaller than the previous value obtained through the scalar virial theorem; that the magnetic field has a negligible effect on the neutron system's equation of state; that the system's magnetic susceptibility increases with the temperature and that the specific heat CV does not significantly change with the magnetic field in the range of temperatures characteristic of proto neutron stars.
We explore the inhomogeneous QCD phases at finite density and temperature using a (3+1)dimensiona... more We explore the inhomogeneous QCD phases at finite density and temperature using a (3+1)dimensional Nambu-Jona-Lasinio (NJL) model in the large Nc limit with an additional attractive tensor-tensor interaction channel. For single modulated solutions, the problem reduces to solving the gap equation of a Chiral Gross-Neveu (N JL2) theory, whose minimum solution is a periodic array of chirally twisted kinks. At zero temperature, the minimum solution reduces to the quarkyonic chiral spiral found in quarkyonic matter. The connection between the quarkyonic matter and our (3+1)-dimensional NJL model is rooted on the fact that the first reduces to (1+1)-dimensional QCD and the second to the N JL2 theory, both of which have continuous chiral symmetry and asymptotic freedom. Our findings can be useful to obtain a reliable qualitative picture of the QCD phase diagram and the location of the QCD critical point in the technically challenging region of intermediate densities and temperatures.
In this review, we discuss the physical characteristics of the magnetic dual chiral density wave ... more In this review, we discuss the physical characteristics of the magnetic dual chiral density wave (MDCDW) phase of dense quark matter and argue 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 staple 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 ...
We investigate the stability of the Magnetic Dual Chiral Density Wave (MD-CDW) phase of cold and ... more We investigate the stability of the Magnetic Dual Chiral Density Wave (MD-CDW) phase of cold and dense QCD against collective low-energy fluctuations of the order parameter. The appearance of additional structures in the system free-energy due to the explicit breaking of the rotational and isospin symmetries by the external magnetic field and the field-induced asymmetry of the lowest Landau level modes play a crucial role in the analysis. The new structures not only affect the condensate minimum equations, but also the spectrum of the thermal fluctuations, which lacks the transverse soft modes that typically affect single-modulated inhomogeneous phases in the absence of a magnetic field. Consequently, the long-range order of the MDCDW phase is preserved at finite temperature. The lack of Landau-Peierls instabilities in the MDCDW phase makes this inhomogeneous phase of dense quark matter particularly relevant for the physics of neutron stars.
Proceedings of XXXIV edition of the Brazilian Workshop on Nuclear Physics — PoS(XXXIV BWNP), 2012
In this talk I review some of the main findings on magnetism in color superconductivity. The phys... more In this talk I review some of the main findings on magnetism in color superconductivity. The physical characteristic of the different phases that are reached by increasing the applied magnetic field in a three-flavor color superconductor at asymptotically high densities are discussed. A mechanism to boost a seed magnetic field in high-dense quark matter is presented. Also, it is shown how a magnetic field can be generated in a color superconductor at moderate densities. Possible implications of these results for the astrophysics of magnetized compact objects are indicated.
The chiral symmetry breaking in a Nambu-Jona-Lasinio effective model of quarks in the presence of... more The chiral symmetry breaking in a Nambu-Jona-Lasinio effective model of quarks in the presence of a magnetic field is investigated. We show that new interaction tensor channels open up via Fierz identities due to the explicit breaking of the rotational symmetry by the magnetic field. We demonstrate that the magnetic catalysis of chiral symmetry breaking leads to the generation of two independent condensates, the conventional chiral condensate and a spin-one condensate. While the chiral condensate generates, as usual, a dynamical fermion mass, the new condensate enters as a dynamical anomalous magnetic moment in the dispersion of the quasiparticles. Since the pair, formed by a quark and an antiquark with opposite spins, possesses a resultant magnetic moment, an external magnetic field can align it giving rise to a net magnetic moment for the ground state. The two condensates contribute to the effective mass of the LLL quasiparticles in such a way that the critical temperature for chiral symmetry restoration becomes enhanced.
Our Universe is full of regions where extreme physical conditions are realized. A most intriguing... more Our Universe is full of regions where extreme physical conditions are realized. A most intriguing case is the super-dense core of neutron stars, some of which also have super-strong magnetic fields, hence called magnetars. In this paper we review the current understanding of the physical properties of the different phases of quark matter at very high densities in the presence of large magnetic fields. We also discuss how the Meissner instability produced at moderate densities by a pairing stress due to the medium neutrality and β -equilibrium constraints can lead to the spontaneous generation of a magnetic field.
In this work we study the dynamical generation of a fermion mass induced by a constant and unifor... more In this work we study the dynamical generation of a fermion mass induced by a constant and uniform external magnetic field in an Abelian gauge model with a Yukawa term. We show that the Yukawa coupling not only enhances the dynamical generation of the mass, but it substantially decreases the magnetic field required for the mass to be generated at temperatures comparable to the electroweak critical temperature. These results indicate that if large enough primordial magnetic fields were present during the early universe evolution, the field-induced generation of fermion masses, which in turn corresponds to the generation of fermion bound states, may play an important role in the electroweak phase transition.
We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a... more 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 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 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.
Bulk and shear viscosity coefficients for systems composed of quasiparticles with medium-modified... more Bulk and shear viscosity coefficients for systems composed of quasiparticles with medium-modified dispersion relations are determined within an effective kinetic theory approach of Boltzmann-Vlasov type. Local conservation of energy and momentum, which is self-consistently embedded in the kinetic theory, implies in thermal equilibrium thermodynamic consistency in quasiparticle approaches.
This paper summarizes some of the recent results on magnetism in high dense mediums, where the ph... more This paper summarizes some of the recent results on magnetism in high dense mediums, where the phenomenon of color superconductivity can be present, and its possible implications for the astrophysics of compact objects. The presentation will be organized through the answers to three fundamental questions.
We investigate the equation of state (EoS) along the BCS-BEC crossover for a quark system describ... more We investigate the equation of state (EoS) along the BCS-BEC crossover for a quark system described by a Nambu-Jona-Lasinio model with multi-fermion interactions. Together with attractive channels for particle-antiparticle (GS) and particle-particle (GD) interactions, a multi-fermion channel with coupling λ that accounts for the diquark-diquark repulsion is also considered. The chiral and diquark condensates are found in the mean-field approximation for different values of the coupling constants. The parameter values where the BCS-BEC crossover can take place are found, and the EoS is used to identify the stability region where the BEC regime has positive pressure. We discuss how the particle density and the repulsive diquark-diquark interaction affect the stability window in the GS − GD plane and find the profile of the pressure versus the density for various values of λ and GD. The effects of λ and GD in the BCS-BEC crossover tend to compensate each other, allowing for a feasible region of densities where the crossover can occur with positive pressure. These results, although mainly qualitative, should serve as a preliminary step in the microscopic analysis required to determine the feasibility of the BCS-BEC crossover and its realization in more realistic models of dense QCD that can be relevant for applications to neutron stars.
Strongly Interacting Matter in Magnetic Fields, 2013
We review the mechanisms via which an external magnetic field can affect the ground state of cold... more We review the mechanisms via which an external magnetic field can affect the ground state of cold and dense quark matter. In the absence of a magnetic field, at asymptotically high densities, cold quark matter is in the Color-Flavor-Locked (CFL) phase of color superconductivity characterized by three scales: the superconducting gap, the gluon Meissner mass, and the baryonic chemical potential. When an applied magnetic field becomes comparable with each of these scales, new phases and/or condensates may emerge. They include the magnetic CFL (MCFL) phase that becomes relevant for fields of the order of the gap scale; the paramagnetic CFL, important when the field is of the order of the Meissner mass, and a spin-one condensate associated to the magnetic moment of the Cooper pairs, significant at fields of the order of the chemical potential. We discuss the equation of state (EoS) of MCFL matter for a large range of field values and consider possible applications of the magnetic effects on dense quark matter to the astrophysics of compact stars.
Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of pair... more Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of paired quark matter in a magnetic field, and taking into consideration the separation between the longitudinal and transverse pressures due to the field-induced breaking of the spatial rotational symmetry, the equation of state (EoS) of the MCFL phase is self-consistently determined. This result is then used to investigate the possibility of absolute stability, which turns out to require a field-dependent "bag constant" to hold. That is, only if the bag constant varies with the magnetic field, there exists a window in the magnetic field vs. bag constant plane for absolute stability of strange matter. Implications for stellar models of magnetized (self-bound) strange stars and hybrid (MCFL core) stars are calculated and discussed.
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Papers by Efrain Ferrer