Lance Labun

Effects of radiation reaction in relativistic laser acceleration

The goal of this paper is twofold: to explore the response of classical charges to electromagnetic force at the level of unity in natural units and to establish a criterion that determines physical parameters for which the related radiation-reaction effects are detectable. In pursuit of this goal, the Landau-Lifshitz equation is solved analytically for an arbitrary (transverse) electromagnetic pulse. A comparative study of the radiation emission of an electron in a linearly polarized pulse for the Landau-Lifshitz equation and for the Lorentz force equation reveals the radiation-reaction-dominated regime, in which radiation-reaction effects overcome the influence of the external fields. The case of a relativistic electron that is slowed down by a counterpropagating electromagnetic wave is studied in detail. We further show that when the electron experiences acceleration of order unity, the dynamics of the Lorentz force equation, the Landau-Lifshitz equation and the Lorentz-Abraham-Dirac equation all result in different radiation emission that could be distinguished in experiment. Finally, our analytic and numerical results are compared with those appearing in the literature.

Dark energy simulacrum in nonlinear electrodynamics

Quasi-constant external fields in nonlinear electromagnetism generate a contribution to the energy-momentum tensor with the form of dark energy. To provide a thorough understanding of the origin and strength of the effects, we undertake a complete theoretical and numerical study of the energy-momentum tensor T for nonlinear electromagnetism. The Euler-Heisenberg nonlinearity due to quantum fluctuations of spinor and scalar matter fields is considered and contrasted with the properties of classical nonlinear Born-Infeld electromagnetism. We also address modifications of charged particle kinematics by strong background fields.

Compact ultradense matter impactors.

We study interactions of meteorlike compact ultradense objects (CUDO), having nuclear or greater density, with Earth and other rocky bodies in the Solar System as a possible source of information about novel forms of matter. We study the energy loss in CUDO puncture of the body and discuss differences between regular matter and CUDO impacts.

Robust characteristics of nongaussian fluctuations from the NJL model

We evaluate the third- and fourth-order baryon, charge and strangeness susceptibilities near a chiral critical point using the Nambu-Jona-Lasinio model. We identify robust qualitative behaviours of the susceptibilities along hypothetical freeze-out lines that agree with previous model studies. Quantitatively, baryon number fluctuations are the largest in magnitude and thus offer the strongest signal when freeze-out occurs farther away from a critical point. Charge and strangeness susceptibilities also diverge at a critical point, but the area where the divergence dominates is smaller, meaning freeze-out must occur closer to a critical point for a signal to be visible in these observables. In case of strangeness, this is attributable to the relatively large strange quark mass. Plotting the third- and fourth-order susceptibilities against each other along the freeze-out line exhibits clearly their non-montonicity and robust features.

QED energy-momentum trace as a force in astrophysics

Abstract We study the properties of the trace T of the QED energy–momentum tensor in the presence of quasi-constant external electromagnetic fields. We exhibit the origin of T in the quantum nonlinearity of the electromagnetic theory. We obtain the quantum vacuum fluctuation-induced interaction of a particle with the field of a strongly magnetized compact stellar object.

Properties of gravitationally bound dark compact ultra dense objects

Abstract We consider compact astrophysical objects formed from dark matter fermions of mass 250 GeV to 100 TeV or from massless fermions hidden by vacuum structure of similar energy scale. These objects have maximum stable masses of sub-planetary scale and radii of micron to centimeter scale. We describe the surface gravity and tidal forces near these compact ultra dense objects, as pertinent to signatures of their collisions with visible matter objects.

Horizons of Strong Field Physics

Discussing the limitations on the validity of classical electrodynamics, we show that present day laser pulse technology applied to head‐on‐collisions with relativistic electrons generates fields strong enough to permit experimentation at the limits of validity of the Lorentz force, and the development of experimental tests of Mach’s principle. We also discuss more distant opportunities for exploring the nature of laws of physics and the vacuum structure. We then conclude that the predictions of quantum electrodynamics in the presence of critical fields are not completely satisfactory and argue that the study of Laser materialization into particle pairs opens a new domain of quantum electrodynamics.

Electromagnetic signal of the QCD phase transition in neutron star mergers

and moderate temperature 50 . T . 90 MeV. These events thus probe a sensitive region of thedensity-temperature phase diagram of QCD matter. We study photon production by the QCDconformal anomaly for a signal of a possible transition to quark degrees of freedom during themerger. We discuss energy loss due to photon radiation as a cooling mechanism that is sensitive tothe bulk viscosity and thermal conductivity of the quark matter.

Spectra of Particles from Laser-Induced Vacuum Decay

The spectrum of electrons and positrons originating from vacuum decay occurring in the collision of two non-colinear laser pulses is obtained. It displays high energy, highly-collimated particle bunches traveling in a direction separate from the laser beams. This result provides an unmistakable signature of the vacuum decay phenomenon and could suggest a new avenue for development of high energy electron and/or positron beams.

Vacuum structure and dark energy

We consider that the universe is trapped in an excited vacuum state and the resulting excitation energy provides the observed dark energy. We explore the conditions under which this situation can arise from physics already known. Considering the example of how macroscopic quantum electrodynamic fields alter the vacuum structure, we find that the energy scale 1 meV–1 eV is particularly interesting. We discuss how dark energy of this form is accessible to laboratory experiments.