arXiv subjects

She-Sheng Xue

Publications and source records attributed to She-Sheng Xue.

At least 73 records · Page 4Linked to original sources

arXiv2014

Nonlinear Breit-Wheeler process in the collision of a photon with two plane waves

The nonlinear Breit-Wheeler process of electron-positron pair production off a probe photon colliding with a low-frequency and a high-frequency electromagnetic wave that propagate in the same direction is analyzed. We calculate the pair-production probability and the spectra of the created pair in the nonlinear Breit-Wheeler processes of pair production off a probe photon colliding with two plane waves or one of these two plane waves. The differences of these two cases are discussed. We evidently show, in the two-wave case, the possibility of Breit-Wheeler pair production with simultaneous photon emission into the low-frequency wave and the high multiphoton phenomena: (i) Breit-Wheeler pair production by absorption of the probe photon and a large number of photons from the low-frequency wave, in addition to the absorption of one photon from the high-frequency wave; (ii) Breit-Wheeler pair production by absorption of the probe photon and one photon from the high-frequency wave with simultaneous emission of a large number of photons into the low-frequency wave. The phenomenon of photon emission into the wave cannot happen in the one-wave case. Compared with the one-wave case, the contributions from high multiphoton processes are largely enhanced in the two-wave case. The results presented in this article show a possible way to access the observations of the phenomenon of photon emission into the wave and high multiphoton phenomenon in Breit-Wheeler pair production even with the laser-beam intensity of order $10^{18}~\rm{W/cm^2}$.

hep-ph↗

arXiv2014

Semiclassical pair production rate for time-dependent electrical fields with more than one component: -WKB-approach and world-line instantons

We present an analytic calculation of the semiclassical electron-positron pair creation rate by time-dependent electrical fields. We use two methods, first the imaginary time method in the WKB-approximation and second the world-line instanton approach. The analytic tools for both methods are generalized to time-dependent electric fields with more than one component. For the WKB method an expansion of the momentum spectrum of produced pairs around the canonical momentum $\vec{P}=0$ is presented which simplifies the computation of the pair creation rate. We argue that the world-line instanton method of [Dunne et al., Phys. Rev. D73, 065028 (2006)] implicitly performs this expansion of the momentum spectrum around $\vec{P}=0$. Accordingly the generalization to more than one component is shown to agree with the WKB result obtained via this expansion. However the expansion is only a good approximation for the cases where the momentum spectrum is peaked around $\vec{P}=0$. Thus the expanded WKB result and the world-line instanton method of [Dunne et al., Phys. Rev. D73, 065028 (2006)] as well as the generalized method presented here are only applicable in these cases. We study the two component case of a rotating electric field and find a new analytic closed form for the momentum spectrum using the generalized WKB method. The momentum spectrum for this field is not peaked around $\vec{P}=0$.

hep-th↗

arXiv2014

Photon-neutrino scattering and the B-mode spectrum of CMB photons

On the basis of the quantum Boltzmann equation governing the time-evolution of the density matrix of polarized CMB photons in the primordial scalar perturbations of metric, we calculate the B-mode spectrum of polarized CMB photons contributed from the scattering of CMB photons and CNB neutrinos (Cosmic Neutrino Background). We show that such contribution to the B-mode spectrum is negligible for small $\ell$, however is significantly large for $50 < \ell< 200$ by plotting our results together with the BICEP2 data. Our study and results imply that in order to theoretically better understand the origin of the observed B-mode spectrum of polarized CMB photons ($r$-parameter), it should be necessary to study the relevant and dominate processes in both tensor and scalar perturbations.

astro-ph.CO↗

arXiv2014

Critical fermion density for restoring spontaneously broken symmetry

We show how the phenomenon of spontaneous symmetry breakdown is affected by the presence of a sea of fermions in the system. When its density exceeds a critical value, the broken symmetry can be restored. We calculate the critical value and discuss the consequences for three different physical systems: First, for the standard model of particle physics, where the spontaneous symmetry breakdown leads nonzero masses of intermediate gauge bosons and fermions. The symmetry restoration will greatly enhance various processes with dramatic consequences for the early universe. Second, for the Gell-Mann--Lèvy $σ$-model of nuclear physics, where the symmetry breakdown gives rise to the nucleon and meson masses. The symmetry restoration may have important consequences for formation or collapse of stellar cores. Third, for the superconductive phase of condensed-matter, where the BCS condensate at low-temperature may be destroyed by a too large electron density.

physics.gen-ph↗

arXiv2014

Surface tension of the core-crust interface of neutron stars with global charge neutrality

It has been shown recently that taking into account strong, weak, electromagnetic, and gravitational interactions, and fulfilling the global charge neutrality of the system, a transition layer will happen between the core and crust of neutron stars, at the nuclear saturation density. We use relativistic mean field theory together with the Thomas-Fermi approximation to study the detailed structure of this transition layer and calculate its surface and Coulomb energy. We find that the surface tension is proportional to a power-law function of the baryon number density in the core bulk region. We also analyze the influence of the electron component and the gravitational field on the structure of the transition layer and the value of the surface tension to compare and contrast with known phenomenological results in nuclear physics. Based on the above results we study the instability against Bohr-Wheeler surface deformations in the case of neutron stars obeying global charge neutrality. Assuming the core-crust transition at nuclear density $ρ_{core}\approx 2.7 * 10^{14}$ g cm$^{-3}$, we find that the instability sets the upper limit to the crust density, $ρ_{crust}^{crit}\approx 1.2 * 10^{14}$ g cm$^{-3}$. This result implies a nonzero lower limit to the maximum electric field of the core-crust transition surface and makes inaccessible a limit of quasilocal charge neutrality in the limit $ρ_{crust}=ρ_{core}$. The general framework presented here can be also applied to study the stability of sharp phase transitions in hybrid stars as well as in strange stars, both bare and with outer crust. The results of this work open the way to a more general analysis of the stability of these transition surfaces, accounting for other effects such as gravitational binding, centrifugal repulsion, magnetic field induced by rotating electric field, and therefore magnetic dipole-dipole interactions.

astro-ph.SR↗

arXiv2014

Electromagnetic and gravitational radiation from the coherent oscillation of electron-positron pairs and fields

Integrating equations of particle-number and energy-momentum conservation and Maxwell field equations, we study the oscillation and drift of electron and positron pairs coherently with fields after these pairs are produced in external electromagnetic fields. From the electric current of oscillating pairs, we obtain the energy spectrum of electromagnetic dipole radiation. This narrow spectrum is so peculiar that the detection of such radiation can identify pair production and oscillation in strong laser fields. We also obtain the energy spectrum of gravitational quadrapole radiation from the energy-momentum tensor of oscillating pairs and fields. Thus, we discuss the generation of gravitational waves on the basis of rapid development of strong laser fields.

physics.plasm-ph↗

arXiv2014

Laser photons acquire circular polarization by interacting with a Dirac or Majorana neutrino beam

It is shown that for the reason of neutrinos being left-handed and their gauge-couplings being parity-violated, linearly polarized photons acquire their circular polarization by interacting with neutrinos. Calculating the ratio of linear and circular polarizations of laser photons interacting with either Dirac or Majorana neutrino beam, we obtain this ratio for the Dirac neutrino case, which is about twice less than the ratio for the Majorana neutrino case. Based on this ratio, we discuss the possibility of using advanced laser facilities and the T2K neutrino experiment to measure the circular polarization of laser beams interacting with neutrino beams in ground laboratories. This could be an additional and useful way to gain some insight into the physics of neutrinos, for instance their Dirac or Majorana nature.

hep-ph↗

arXiv2014

Circular polarization from linearly polarized laser beam collisions

To probe the nonlinear effects of photon-photon interaction in the quantum electrodynamics, we study the generation of circular polarized photons by the collision of two linearly polarized laser beams. In the framework of the Euler-Heisenberg effective Lagrangian and the Quantum Boltzmann equation for the time evolution of the density matrix of polarizations, we calculate the intensity of circular polarizations generated by the collision of two linearly polarized laser beams and estimate the rate of generation. As a result, we show that the generated circular polarization can be experimentally measured, on the basis of optical laser beams of average power KW, which are currently available in laboratories. Our study presents a valuable supplementary to other theoretical and experimental frameworks to study and measure the nonlinear effects of photon-photon interaction in the quantum electrodynamics.

physics.optics↗

arXiv2013

Higgs Boson and Top-Quark Masses and Parity-Symmetry Restoration

The recent ATLAS and CMS experiments show the first observations of a new particle in the search for the Standard Model Higgs boson at the LHC. We revisit the scenario that high-dimensional operators of fermions must be present due to the theoretical inconsistency of the fundamental cutoff (quantum gravity) with the parity-violating gauge symmetry of the Standard Model. Studying the four-fermion interaction of the third quark family, we show that at an intermediate energy threshold E\approx 4.27 TeV for the four-fermion coupling being larger than a critical value, the spontaneous symmetry-breaking phase transits to the strong-coupling symmetric phase where composite Dirac fermions form fully preserving the chiral gauge symmetry of the Standard Model and the parity-symmetry is restored. Under this circumstance, we perform the standard analysis of renormalization-group equations of the Standard Model in the spontaneous symmetry-breaking phase. As a result, the Higgs boson mass m_H\approx 126.7 GeV and top-quark mass m_t\approx 172.7 GeV are obtained without drastically fine-tuning the four-fermion coupling.

hep-ph↗

arXiv2013

Einstein-Euler-Heisenberg Theory and charged black holes

Taking into account the Euler-Heisenberg effective Lagrangian of one-loop nonperturbative quantum electrodynamics (QED) contributions, we formulate the Einstein-Euler-Heisenberg theory and study the solutions of nonrotating black holes with electric and magnetic charges in spherical geometry. In the limit of strong and weak electromagnetic fields of black holes, we calculate the black hole horizon radius, area, and total energy up to the leading order of QED corrections and discuss the black hole irreducible mass, entropy, and maximally extractable energy as well as the Christodoulou-Ruffini mass formula. We find that these black hole quantities receive the QED corrections, in comparison with their counterparts in the Reissner-Nordström solution. The QED corrections show the screening effect on black hole electric charges and the paramagnetic effect on black hole magnetic charges. As a result, the black hole horizon area, irreducible mass, and entropy increase; however, the black hole total energy and maximally extractable energy decrease, compared with the Reissner-Nordström solution. In addition, we show that the condition for extremely charged black holes is modified due to the QED correction.

hep-th↗

arXiv2013

Fractional Effective Action at strong electromagnetic fields

In 1936, Weisskopf showed that for vanishing electric or magnetic fields the strong-field behavior of the one loop Euler-Heisenberg effective Lagrangian of quantum electro dynamics (QED) is logarithmic. Here we generalize this result for different limits of the Lorentz invariants $\vec{E}^2-\vec{B}^2$ and $\vec{B}\cdot\vec{E}$. The logarithmic dependence can be interpreted as a lowest-order manifestation of an anomalous power behavior of the effective Lagrangian of QED, with critical exponents $δ=e^2/(12π)$ for spinor QED, and $δ_S=δ/4$ for scalar QED.

hep-th↗

arXiv2013

Gravitational and electric energies in the collapse of a spherical thin-shell capacitor

We adopt a simplified model describing the collapse of a spherical thin-shell capacitor to give an analytical description how gravitational energy is converted to both kinetic and electric energies in the gravitational collapse. It is shown that (i) averaged kinetic and electric energies are the same order, about an half of gravitational energy of spherical thin-shell capacitor in the collapse; (ii) caused by radiating and rebuilding electric energy, the gravitational collapse undergoes a sequence of "on and off" hopping steps in the microscopic Compton scale. Although the collapse process is still continuous in terms of macroscopic scales, it is slowed down as the kinetic energy is reduced and collapsing time is about an order of magnitude larger than that of the collapse process eliminating electric processes.

gr-qc↗

arXiv2013

Why is the top quark much heavier than other fermions?

The recent ATLAS and CMS experiments show the first observations of a new particle in the search for the Standard Model Higgs boson at the LHC. We revisit the theoretical inconsistency of the fundamental high-energy cutoff with the parity-violating gauge symmetry of local quantum field theory for the standard model. This inconsistency suggests high-dimensional operators of fermion interactions, which are attributed to the quantum gravity. In this letter, recalling the minimal dynamical symmetry-breaking mechanism, we show that it is energetically favorable for the top quark to acquire its mass via spontaneous symmetry breaking, whereas other fermions acquire their masses via explicit symmetry breaking.

hep-ph↗

arXiv2013

Vacuum pair-production in a classical electric field and an electromagnetic wave

Using semiclassical WKB-methods, we calculate the rate of electron-positron pair-production from the vacuum in the presence of two external fields, a strong (space- or time-dependent) classical field and a monochromatic electromagnetic wave. We discuss the possible medium effects on the rate in the presence of thermal electrons, bosons, and neutral plasma of electrons and protons at a given temperature and chemical potential. Using our rate formula, we calculate the rate enhancement due to a laser beam, and discuss the possibility that a significant enhancement may appear in a plasma of electrons and protons with self-focusing properties.

physics.plasm-ph↗

arXiv2012

Euler-Heisenberg Lagrangian and photon circular polarization

Considering the effective Euler-Heisenberg Lagrangian, i.e., non-linear photon-photon interactions, we study the circular polarization of electromagnetic radiation based on the time-evolution of Stokes parameters. To the leading order, we solve the Quantum Boltzmann Equation for the density matrix describing an ensemble of photons in the space of energy-momentum and polarization states, and calculate the intensity of circular polarizations. Applying these results to a linear polarized thermal radiation, we calculate the circular polarization intensity, and discuss its possible relevance to the circular polarization intensity of the Cosmic Microwave Background radiation.

hep-ph↗

arXiv2012

High-energy neutrino emission in gravitational collapses

In this article, we present a study of high-energy neutrino emission in gravitational collapse. A compact star is treated as a complete degenerate Fermi gas of neutrons, protons and electrons. In gravitational collapse, its density reaches the thresholds for muon and pion productions, leading to high-energy neutrinos production. By using adiabatic approximation that macroscopic collapsing processes are much slower than microscopic processes of particle interactions, we adopt equilibrium equations of microscopic processes to obtain the number of neutrino productions. Assuming 10% of variation in gravitational binding energy converted to the energy of produced neutrinos, we obtain fluxes of 10MeV electron-neutrinos and GeV electron and muon neutrinos. In addition, we compute the ratio (< 1) of total muon neutrino number to the total electron neutrino number at the source and at the Earth considering neutrino oscillations. We approximately obtain the number of GeV antineutrino events (\gtrsim 1) in an ordinary detector such as Kamiokande and total energy of neutrino flux (\gtrsim 10^{53} erg), as a function of collapsing star mass.

astro-ph.HE↗

arXiv2012

Electron and positron pair production of compact stars

Neutral stellar core at or over nuclear densities is described by a positive charged baryon core and negative charged electron fluid since they possess different masses and interactions. Based on a simplified model of a gravitationally collapsing or pulsating baryon core, we approximately integrate the Einstein-Maxwell equations and the equations for the number and energy-momentum conservation of complete degenerate electron fluid. We show possible electric processes that lead to the production of electron-positron pairs in the boundary of a baryon core and calculate the number and energy of electron-positron pairs. This can be relevant for understanding the energetic sources of supernovae and gamma-ray bursts.

astro-ph.HE↗

arXiv2012

High energy neutrino oscillation at the presence of the Lorentz Invariance Violation

Due to quantum gravity fluctuations at the Planck scale, the space-time manifold is no longer continuous, but discretized. As a result the Lorentz symmetry is broken at very high energies. In this article, we study the neutrino oscillation pattern due to the Lorentz Invariance Violation (LIV), and compare it with the normal neutrino oscillation pattern due to neutrino masses. We find that at very high energies, neutrino oscillation pattern is very different from the normal one. This could provide an possibility to study the Lorentz Invariance Violation by measuring the oscillation pattern of very high energy neutrinos from a cosmological distance.

hep-ph↗