Modified magnetohydrodynamics around the electroweak transition

Pavlović, Petar; Leite, Natacha; Sigl, Günter

doi:10.1088/1475-7516/2016/06/044

Cited by 15 publications

(36 citation statements)

References 48 publications

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“…On the other hand, if the fields are initially helical with initially vanishing chiral asymmetry, a finite µ 5 will in general be generated (and vice versa) [38], which implies that the evolution for later times will be different from the standard MHD description.…”

Section: Modified Mhd Equationsmentioning

confidence: 99%

“…of (20) becomes comparable to the second term proportional to the magnetic energy term, the above approximation can no longer be applied and one needs to consider the full set of coupled differential equations for energy end helicity density. In that regime, even a qualitative understanding of the interrelationship between MHD turbulence and the chiral anomaly effect is not so simple, since on the one hand chiral anomaly also leads to inverse cascade [37,38], but on the other hand MHD inverse cascade is supported by the conservation of helicity, while the anomaly effect is based on the change of helicity, as discussed above. It therefore seems natural that a system will tend to approach the state where one of the effects -either MHD turbulence or the chiral anomaly -dominates and determines the main features of its dynamics, while the other one has a minor role, which can be treated as a correction.…”

Section: Inverse Cascade and The Role Of Helicitymentioning

confidence: 99%

“…It is then possible to use the already known properties of standard MHD turbulence and observe the modifications induced by the chiral anomaly effect. The weak anomaly regime is also of physical interest in at least some important cases, for instance around the electroweak transition where the chiral effects are expected to be small with respect to the standard MHD background [38]. We expect that the overall dynamics will in this regime be determined by the usual MHD terms (i.e.…”

Section: Weak Anomaly Regimementioning

confidence: 99%

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Chiral magnetohydrodynamic turbulence

2017

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In this work the influence of the chiral anomaly effect on the evolution of magnetohydrodynamic turbulence was studied. We argue that before the electroweak symmetry breaking and for temperatures high enough such that the electron mass can be ignored, the description of a charged plasma in general needs to take into account the interplay between turbulence and the anomaly effects. It was demonstrated that this generalization can have important consequences on the evolution of turbulence, leading to the creation of maximally-helical fields from initially non-helical ones. Therefore, chiral effects can strongly support turbulent inverse cascade, and lead to a slower decrease of the magnetic field with time, and also to a faster growth of the correlation length, when compared to the evolution predicted by the standard magnetohydrodynamics description. Using the weak anomaly approximation, and treating the anomaly contributions to magnetic energy and helicity as a small perturbation, we derive the specific solutions for the inverse cascade regime that demonstrate how chiral effects support the inverse cascade.

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Section: Modified Mhd Equationsmentioning

confidence: 99%

Section: Inverse Cascade and The Role Of Helicitymentioning

confidence: 99%

Section: Weak Anomaly Regimementioning

confidence: 99%

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Chiral magnetohydrodynamic turbulence

2017

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“…This contribution to the electric current causes an instability in the system (Joyce & Shaposhnikov 1997) that has been analyzed in many works (Fröhlich & Pedrini 2000;Ooguri & Oshikawa 2012;Boyarsky et al 2012a;Kumar et al 2014;Grabowska et al 2015;Manuel & Torres-Rincon 2015;Buividovich & Ulybyshev 2016;Boyarsky et al 2015;). This instability may be relevant in the physics of the early universe (Joyce & Shaposhnikov 1997;Fröhlich & Pedrini 2000, 2002Semikoz & Sokoloff 2004;Semikoz et al 2009;Boyarsky et al 2012a,b;Semikoz et al 2012;Tashiro et al 2012;Dvornikov & Semikoz 2012, 2014Manuel & Torres-Rincon 2015;Gorbar et al 2016;Pavlović et al 2016;Pavlović et al 2017), of the quark-gluon plasmas (Akamatsu & Yamamoto 2013;Taghavi & Wiedemann 2015;Hirono et al 2015), or of neutron stars (Ohnishi & Yamamoto 2014;Dvornikov & Semikoz 2015a,b;Yamamoto 2016;Dvornikov 2016). However, to the best of our knowledge, a systematic analysis of the system of chiral MHD equations, including the back-reaction of the magnetic field on the chiral chemical potential and the coupling to the plasma velocity field, U (t, x) appears to be missing.…”

Section: Introductionmentioning

confidence: 99%

Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory

Rogachevskii

Ruchayskiy²,

Boyarsky

et al. 2017

ApJ

125

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The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right-and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma (chiral magnetic effect ). We present a self-consistent treatment of the chiral MHD equations, which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that the chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the largescale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark-gluon plasma.

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“…[55] which assumes that the system passes abruptly from the symmetric phase to the broken phase (in a way similar to that of Ref. [75]). Then, we can estimate the strength B and the magnetic helicity A.B of the magnetic field after the symmetry breaking.…”

Section: Summary and Discussionmentioning

confidence: 99%

Effects of theUY(1)Chern-Simons term and its baryonic contribution on matter asymmetries and hypermagnetic fields

Zadeh

Gousheh

2017

Phys. Rev. D

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In this paper, we study the significance of the U Y (1) Chern-Simons term in general, and its baryonic contribution in particular, for the evolution of the matter asymmetries and the hypermagnetic field in the temperature range 100GeV≤ T ≤ 10TeV. We show that an initial helical hypermagnetic field, denoted by B (0) Y , can grow matter asymmetries from zero initial value. However, the growth which is initially quadratic with respect to B (0) Y , saturates for values larger than a critical value. The inclusion of the baryonic contribution reduces this critical value, leading to smaller final matter asymmetries. Meanwhile, B Y (T EW ) becomes slightly larger than B (0)Y . In the absence of the U Y (1) Chern-Simons term, the final values of matter asymmetries grow without saturation. Conversely, we show that an initial matter asymmetry can grow an initial seed of hypermagnetic field, provided the Chern-Simons term is taken into account. The growth process saturates when the matter asymmetry drops abruptly. When the baryonic contribution is included, the saturation occurs at an earlier time, and B Y (T EW ) becomes larger. We also show that the baryonic asymmetry and the magnetic field strength can be within the acceptable range of present day data, provided the inverse cascade process is also taken into account; however, the magnetic field scale obtained from this simple model is much lower than the ones usually assumed for gamma ray propagation. * S − Rostamzadeh@sbu.ac.ir † ss−gousheh@sbu.ac.ir 1 arXiv:1607.00650v3 [hep-ph]

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Modified magnetohydrodynamics around the electroweak transition

Cited by 15 publications

References 48 publications

Chiral magnetohydrodynamic turbulence

Chiral magnetohydrodynamic turbulence

Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory

Effects of theUY(1)Chern-Simons term and its baryonic contribution on matter asymmetries and hypermagnetic fields

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