Anomaly-Induced Dynamical Refringence in Strong-Field QED

Mueller, Niklas; Hebenstreit, Florian; Berges, Jürgen

doi:10.1103/physrevlett.117.061601

Cited by 31 publications

(40 citation statements)

References 49 publications

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“…This relation has been proven to hold in the continuum limit in the context of the Euclidean lattice gauge theory [63,64]. In the context of the real-time lattice computations, it has been numerically confirmed for nonexpanding systems [47][48][49]57].…”

Section: Axial Anomaly On the Latticementioning

confidence: 91%

“…To manifest the axial anomaly on a lattice, one has to take care of the fermion doubling problem [53]. In the context of the real-time lattice simulations, the Wilson fermion method has been successfully applied to the description of the axial anomaly in nonexpanding systems [47][48][49][54][55][56][57]. We will employ the Wilson fermion method that is extended to the expanding geometry, which was first introduced in Ref.…”

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confidence: 99%

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Nonequilibrium axial charge production in expanding glasma flux tubes

Tanji

2018

Phys. Rev. D

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Axial charge production at the early stage of heavy-ion collisions is investigated within the framework of real-time lattice simulations at leading order in QCD coupling. Starting from color glass condensate initial conditions, the time evolution of quantum quark fields under classical color gauge fields is computed on a lattice in longitudinally expanding geometry.We consider simple color charge distributions in Lorentz contracted nuclei that realize flux tube-like configurations of color fields carrying nonzero topological charge after a collision.By employing the Wilson fermion extended to the longitudinally expanding geometry, we demonstrate the realization of the axial anomaly on the real-time lattice. I. INTRODUCTIONIn relativistic heavy-ion collisions, CP-violating configurations of color gauge fields can be generated locally either by gauge field dynamics at the instant of a collision or sphaleron transitions at later times [1][2][3][4][5]. Quarks interacting with such gauge fields induce the imbalance of axial charge due to the quantum phenomenon of axial anomaly. In presence of a strong U(1) magnetic field, which may be generated in off-central collisions, the axial charge asymmetry can be converted to a flow of electric current along the magnetic field [6]. This phenomenon is called chiral magnetic effect (CME) [7][8][9]. Experimental searches for this novel phenomenon have been carried out at RHIC and the LHC [10-12], where a charge dependence of azimuthal correlations was measured [13]. However, the observation of the CME in heavy-ion collisions still remains inconclusive due to large backgrounds [14].On the theory side, there have been numerous developments in the description of the transport phenomena associated with the CME based on the chiral kinetic theories [15][16][17][18][19][20] and the anomalous hydrodynamics [21][22][23][24][25][26]. To make predictions of observable consequences of the CME, some of these frameworks need the information of the axial charge distribution as an initial condition as well as * ntanji@ectstar.eu arXiv:1805.00775v2 [hep-ph] 19 Jul 2018 the space-time distribution of the magnetic field. Since the lifetime of the magnetic field is expected to be short < ∼ 1 fm/c [27][28][29], the understanding of the axial charge production at the early stage of heavy-ion collisions is indispensable in order to make reliable predictions about the CME.At high energies, colliding heavy-ions can be described in terms of the effective theory of color glass condensate (CGC) [30][31][32]. By a collision, strong color electromagnetic fields are generated, and the system expands to the longitudinal direction in a nearly boost-invariant way. Even though the QCD coupling is weak g 1, this system, called glasma [2], is strongly correlated because the gauge fields are inversely proportional to the coupling constant A ∼ 1/g as a consequence of the gluon saturation. Nonperturbative dynamics of these gauge fields can be computed by classical(statistical) gauge field simulations on the real-time ...

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Section: Axial Anomaly On the Latticementioning

confidence: 91%

mentioning

confidence: 99%

Nonequilibrium axial charge production in expanding glasma flux tubes

Tanji

2018

Phys. Rev. D

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“…The rigorous way to study this fermion production may be to track the real time evolution of all the correlators, such as gauge bosons and fermions, simultaneously in the presence of the slowly rolling φ, starting for instance from first principles like the closed-time-path formalism [45][46][47]. This treatment is however beyond the scope of this paper.…”

Section: Chiral Fermion Production From the Helical Gauge Fieldmentioning

confidence: 99%

Gauge field and fermion production during axion inflation

Domcke¹,

Mukaida²

2018

J. Cosmol. Astropart. Phys.

129

223

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We study the dual production of helical Abelian gauge fields and chiral fermions through the Chern-Simons (CS) coupling with a pseudo-scalar inflaton in the presence of a chiral anomaly. Through the CS term, the motion of the inflaton induces a tachyonic instability for one of the two helicities of the gauge field. We show that the resulting helical gauge field necessarily leads to the production of chiral fermions by deforming their Fermi sphere into discrete Landau levels. The population of the lowest Landau level leads to a chiral asymmetry as inferred from the chiral anomaly, while the higher levels are populated symmetrically through pair production. From the backreaction of the fermions on the gauge field production we derive a conservative but stringent upper bound on the magnitude of the gauge fields. Consequently, we find that the scalar perturbations sourced by these helical gauge fields, responsible for enhanced structure formation on small scales, get reduced significantly. We also discuss the fate of the primordial chiral asymmetry and of the helical gauge fields after inflation, and show that the instability in the chiral plasma tends to erase these primordial asymmetries. This result may impact scenarios where the baryon asymmetry of the Universe is connected to primordial magnetic fields.

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“…Moreover, pair production can also take place in time-varying electric [5,6] or scalar backgrounds, and it can be regarded as a very important non-perturbative process in quantum field theory [7]. It is also fundamental to understand the reheating epoch in cosmology [8], non-equilibrium processes induced by strong fields [9,10], and astrophysical phenomena [11].…”

Section: Introductionmentioning

confidence: 99%

Breaking of adiabatic invariance in the creation of particles by electromagnetic backgrounds

et al. 2019

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Particles are spontaneously created from the vacuum by time-varying gravitational or electromagnetic backgrounds. It has been proven that the particle number operator in an expanding universe is an adiabatic invariant. In this paper we show that, in some special cases, the expected adiabatic invariance of the particle number fails in presence of electromagnetic backgrounds. Furthermore, we also show a close relation between the breaking of the adiabatic invariance and the emergence of the axial anomaly.

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Anomaly-Induced Dynamical Refringence in Strong-Field QED

Cited by 31 publications

References 49 publications

Nonequilibrium axial charge production in expanding glasma flux tubes

Nonequilibrium axial charge production in expanding glasma flux tubes

Gauge field and fermion production during axion inflation

Breaking of adiabatic invariance in the creation of particles by electromagnetic backgrounds

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