Electron-positron pair production in ultrastrong laser fields

Electronepositron pair production due to the decay of vacuum in ultrastrong laser fields is an interesting topic which is revived recently because of the rapid development of current laser technology.The theoretical and numerical research progress of this challenging topic is reviewed.Many new findings are presented by different approaches such as the worldline instantons,the S-matrix theory,the kinetic method by solving the quantum Vlasov equation or/and the real-time DiraceHeisenbergeWigner formalism,the computational quantum field theory by solving the Dirac equation and so on.In particular,the effects of electric field polarizations on pair production are unveiled with different patterns of created momentum spectra.The effects of polarizations on the number density of created particles and the nonperturbative signatures of multiphoton process are also presented.The competitive interplay between the multiphoton process and nonperturbation process plays a key role in these new findings.These newly discovered phenomena are valuable to deepen the understanding of pair production in complex fields and even have an implication to the study of strong-field ionization.More recent studies on the pair production in complex fields as well as beyond laser fields are briefly presented in the view point of perspective future.

Electron-Positron Pair Production in Electro-Magnetic Field

At very high energies, pair production formation (γ + N → e+e-) exhibits a variety of intriguing properties. Analytically and quantitatively, the formation of Electron-Positron pairs in the Electro-Magnetic field of light nuclei has been calculated. In Ultra-Relativistic (UR) areas of incident photon energy, applying the resulting formulas to the energy distribution of the (e-, e+) operation. When we compare the results, we can observe that the Magnetic field of the target nucleus is more efficacious than the Electric field of the nucleus in the (e-, e+) operation. Furthermore, we can show that in Pair Production operation, the Differential Cross Section (DCS) owing to the target nucleus’s Electric Quadrupole (EQ) and Magnetic Octupole (MO) are bigger than the Differential Cross Section (DCS) attributable to the target nucleus’s Electric Charge (EC) distribution and Magnetic Dipole (MD).

Effect of symmetrical frequency chirp on pair production

By using Dirac–Heisenberg–Wigner formalism we study electron–positron pair production for linear, elliptic, nearly circular, and circular polarizations of electric fields with symmetrical frequency chirp, and we obtain momentum spectra and pair yield. The difference of results among polarized fields is obvious for the small chirp. When the chirp parameter increases, the momentum spectra tend to exhibit the multiphoton pair generation that is characterized by the multi-concentric ring structure. The increase of the number density is also remarkable compared to the case of asymmetrical frequency chirp. Note that the dynamically assisted Schwinger mechanism plays an important role for the enhanced pair production in the symmetrical frequency chirp.

Hidden conformal symmetry and pair production near the cosmological horizon in Kerr-Newman-Taub-NUT-de Sitter spacetime

We show that the study of the hidden conformal symmetry that is associated with the Kerr/CFT correspondence can also apply to the cosmological horizon in the Kerr-Newman-Taub-NUT-de Sitter spacetime.This symmetry allows employing some two dimensional conformal field theory methods to understand the properties of the cosmological horizon.The entropy can be understood by using the Cardy formula,and the equation for the scattering process in the near region is in agreement with that obtained from a two point function in the two-dimensional conformal field theory.We also show that pair production can occur near the cosmological horizon in Kerr-Newman-Taub-NUT-de Sitter for near extremal conditions.

Dynamically assisted pair production for scalar QED by two fields

By solving the quantum Vlasov equation, the dynamically assisted pair production for scalar quantum electrodynamics （QED） is investigated. It is verified that this mechanism still holds true for boson pair production. Two combinations of two electric fields having different time scales under various time delays are considered; it is found that the oscillations of the momentum spectrum and the number density of created bosons decrease with increasing time delay, and the latter has a maximum value when the time delay equals zero. Furthermore, the differences in vacuum pair production between bosons and fermions are also studied, and they are helpful for distinguishing the created bosons from fermions.

Electron-positron pair production in a strong asymmetric laser electric field

By solving the quantum Vlasov equation, electron positron pair production in a strong electric field with asymmetric laser pulses has been investigated. We consider three different situations of subcycle, cycle and supercycle laser pulses. It is found that in asymmetric laser pulse field, i.e.. when the pulse length of one rising or falling side is fixed while the pulse length of the other side is changed, the pair production rate and mnnber density can be significantly modified comparable to symmetric situation. For each ca,se of these three different cycle pulses, when one side pulse length is constant and the other side pulse length becomes shorter, i.e., the whole pulse is compressed, the more pairs can be produced than that in tile vice versa case, i.e., the whole pulse is elongated. In compressed pulse case there exists an optimum pulse length ratio of asylnmetric pulse lengths which makes the pair number density maximunn. Moreover, the created maximum pair number density by subcycle pulse is larger than that by cycle or/and supercycle pulse. In elongated pulse case, however, only for supercycle laser pulse the created pairs is enhanced and there exists also an optimum asymmetric pulse length ratio that maximizes the pair number density. On the other hand. surprisingly, in both cases of subcycle and cycle elongated laser pulses, the pair number density is monotonically decreasing as the asymmetry of pulse increases.

Electron-positron pair production in the low-density approximation

Electron-positron pair creation is studied in the low-density approximation by solving the quantum Vlasov equation exactly and the mapping equation approximately. The simpler mapping equation is an approximate treatment of the quantum Vlasov equation in which the continuous external field is regarded as a series of delta kicks. Our study indicates that this new treatment is appropriate because the results of the two methods are in good agreement with each other. However, as the period number increases, interference and a complicated structure in the momentum distribution are observed. Furthermore, we also obtain the square power law relation of the number density to the applied electric field strength.

Pair production of the Elementary Goldstone Higgs boson at the LHC

The Elementary Goldstone Higgs（EGH） model is a perturbative extension of the standard model（SM）,which identifies the EGH boson as the observed Higgs boson. In this paper, we study pair production of the EGH boson via gluon fusion at the LHC and find that the resonant contribution of the heavy scalar is very small and the SM-like triangle diagram contribution is strongly suppressed. The total production cross section mainly comes from the box diagram contribution and its value can be significantly enhanced with respect to the SM prediction.

Scalar-pseudoscalar pair production at the Large Hadron Collider at NLO+NLL accuracy in QCD

We thoroughly investigate both transverse momentum and threshold resummation effects on scalar-pseudoscalar pair production via quark-antiquark annihilation at the 13 TeV Large Hadron Collider at QCD NLO+NLL accuracy.A factorization method is introduced to properly supplement the soft-gluon(threshold)resummation contribution from parton distribution functions to the resummed results obtained by the Collins-Soper-Ster-man resummation approach.We find that the impact of the threshold-resummation improved PDFs is comparable to the resummation effect of the partonic matrix element and can even predominate in high invariant mass regions.Moreover,the loop-induced gluon-gluon fusion channel in the type-I two-Higgs-doublet model is considered in our calculations.The numerical results show that the electroweak production via quark-antiquark annihilation dominates over the gluon-initiated QCD production by 1-2 orders of magnitude.

Pair production in Reissner-Nordstrom-Anti de Sitter black holes

We studied the pair production of charged scalar particles of a five-dimensional near extremal Reissner-Nordström-Anti de Sitter(RN-AdS_(5))black hole.The pair production rate and the absorption cross section ratio in full spacetime are obtained and are shown to have a concise relation with their counterparts in the near horizon region.In addition,the holographic descriptions of the pair production,both in the IR CFT in the near horizon region and the UV CFT at the asymptotic spatial boundary of the RN-AdS_(5) black hole,are analyzed in the AdS_(2)/CFT_(1) and AdS_(5)/CFT_(4) correspondences,respectively.This work gives a complete description of scalar pair production in a near extremal RN-AdS_(5) black hole.

Asymmetric pulse effects on pair production in polarized electric fields

Using the Dirac–Heisenberg–Wigner formalism,effects of the asymmetric pulse shape on the generation of electronpositron pairs in three typical polarized fields,i.e.,linear,middle elliptical and circular fields,are investigated.Two kinds of asymmetries for the falling pulse length,short and elongated,are studied.We find that the interference effect disappears with the shorter pulse length and that the peak value of the momentum spectrum is concentrated in the center of the momentum space.In the case of the extending falling pulse length,a multiring structure without interference appears in the momentum spectrum.Research results show that the momentum spectrum is very sensitive to the asymmetry of the pulse as well as to the polarization of the fields.We also find that the number density of electronpositron pairs under different polarizations is sensitive to the asymmetry of the electric field.For the short falling pulse,the number density can be significantly enhanced by over two orders of magnitude.These results could be useful in planning high-power and/or high-intensity laser experiments.

Pair production of Higgs boson in NMSSM at the LHC with the next-to-lightest C P-even Higgs boson being SM-like

The next-to-minimal supersymmetric standard model （NMSSM） more naturally accommodates a Higgs boson with a mass of approximately 125 GeV than the minimal supersymmetric standard model （MSSM）. In this work, we assume that the next-to-lightest CP-even Higgs boson h2 is the SM-like Higgs boson h, whereas the lightest CP-even Higgs boson h1 is dominantly singlet-like. We discuss the h1h1, h2h2, and h1h2 pair production processes via gluon-gluon fusion at the LHC for an collision energy of 14 TeV, and we consider the cases in which one Higgs boson decays to bb and the other decays to γγ or τ＋τ-. We find that, for mh1？ 62 GeV, the cross section of the gg→h1h1 process is relatively large and maximally reaches 5400 fb, and the production rate of the h1h1→bbτ＋τ-final state can reach 1500 fb, which make the detection of this final state possible for future searches of an integrated luminosity of 300 and 3000 fb-1. This is mainly due to the contributions from the resonant production process pp→h2→h1h1 and the relatively large branching ratio of h1→bb and h1→τ＋τ-. The cross sections of the pp→h2h2 and pp→h1h2 production processes maximally reach 28 fb and 133 fb, respectively.

Pair of dyon production near magnetized dyonic Reissner-Nordstrom black holes

We investigate the phenomenon of pair production of massive scalar particles with magnetic charge near the horizon of a magnetized dyonic Reissner-Nordstrom black hole.The intrinsic symmetry between the electric and magnetic quantities in the Einstein-Maxwell equations suggests that the pair can be generated through Hawking radiation and the Schwinger effect,provided that the Dirac quantization condition is satisfied.

The Real Reason Why the Electron’s Bare g-Factor Is 2 Times Classical

When analyzing an Electron’s orbit’s and movements, a “classical” bare g-factor of “1” must be used, but when analyzing just the Electron itself, a bare g-factor and gyromagnetic ratio of twice the “classical” value is needed to fit reality. Nobody has fully explained this yet. By examining the electromagnetic wave nature of the electron, it is possible to show a simple reason why its bare g-factor must be 2, without resorting to superluminal velocities or dismissing it as mystically intrinsic. A simple charged electromagnetic wave loop (CEWL) model of the electron that maintains the same electromagnetic wave nature as the high-energy photons from which electron-positron pairs form, will have exactly half of its energy in the form of magnetic energy who’s field lines are perpendicular to the direction of the charge rotation, which leads to the conclusion that only half of the electron’s electromagnetic mass is rotational mass, from which it is easy to calculate a bare g-factor of 2 using Feynman’s equation for the electron’s g-factor.

Exceedingly Small Quantum of Time Kshana Explains the Structure of an Electron

In this study, an effort is made to find the attributes of an electron based on Maharishi Vyasa’s definition of kshana or moment. Kshana or moment is a very small quanta of time defined by Maharishi Vyasa. It is the time taken by an elementary particle to change the direction from east to north. It is found that the value of a kshana in the case of pair production is approximately 2 × 10-21 sec, and the radius of the spinning electron or positron is equal to the reduced Compton wavelength. The mass of the electron is equal to the codata recommended value of electron mass and time required in pair production is about four kshanas equal to spinning period of an electron. During validation, in case of the photoelectric effect, spectral series of hydrogen atoms, Compton scattering, and the statistical concept of motion of electron, the value of the number of kshanas in a second is the same as that found in pair production.

Theoretical Explanation of m = E/c2

The aim of this theory is to study and explain the phenomena that have been predicted by Einstein in the year 1905 which affirms that the mass of a body increases with velocity;the mass of a body increases when it travels at high speed. In classical physics, it gains in the energy of motion. In relativity that kinetic energy makes itself felt as additional mass. As the object reaches the speed of light, theoretically, its mass becomes “infinite”. Nevertheless, the concept of “infinite mass” is still a subject we know little about. In the following paper, I will be focusing on how and why such phenomena take place. Furthermore, we shall discuss antimatter. Antimatter is now known to shower down from the sky above us, and when a particle meets its antiparticle, both of them disappear in a burst of radiant energy, exactly in accordance with E = mc2 .

The impact of ATLAS and CMS single differential top-quark pair measurements at √s=8 TeV on CTEQ-TEA PDFs

By applying the Error PDF Updating Method,we analyze the impact of the absolute and normalized single differential cross-sections for top-quark pair production data from the ATLAS and CMS experiments at the Large Hadron Collider,at a center-of-mass energy of √s=8TeV,on the CT14HERA2 PDFs.We find that the top quark pair single differential distributions provide minor constraints on the CT14HERA2 gluon PDF when the nominal CT14HERA2 inclusive jet production data are included in the fit.Larger constraints on the gluon distribution are present when the jet data are removed(CT14HERA2mJ)and/or when increased weights are given to the top data in the CT14HERA2 fits.The weighted$t\bar t$data provide significant constraints on the CT14HERA2mJ gluon PDF,which are comparable to those obtained from inclusive jet production data.Furthermore,we examine the top quark mass sensitivity of the top-quark pair single differential distributions.

Numerical investigation and potential tunability scheme on e^+e^- and π^+π^- stimulated pair creation from vacuum using high intensity laser beams

Numerical estimates for electrons and mesons particle–antiparticle creation from vacuum in the presence of strong electromagnetic fields are derived, using the complete probability density relation of Popov's imaginary time method(Popov, JETP Lett. 13, 185(1971); Sov. Phys. JETP 34, 709(1972); Sov. Phys. JETP 35, 659(1972); Popov and Marinov, Sov. J. Nucl. Phys. 16, 449(1973); JETP Lett. 18, 255(1974); Sov. J. Nucl. Phys. 19, 584(1974));(Popov,Phys. Let. A 298, 83(2002)), and within the framework of an experimental setup like the E144(Burke et al., Phys. Rev.Lett. 79, 1626(1997)). The existence of crossing point among pair creation efficiency curves of different photon energies and the role of odd/even multiphoton orders in the production rates are discussed. Finally a kind of tunability process between the two creation processes is discussed.

Stellar energy loss rates associated with photoneutrino processes in the minimal extension of the standard model

Using the minimal extension of the standard model and considering the charge radius and the anapole moments of a neutrino,we derive analytical expressions for the stellar energy loss rates associated with the production of a neutrino pair e+γ→ve+ve νein hot plasma under three limiting regimes(nondegenerate,intermediate,and degenerate electrons)of the temperature,electron chemical potential,and plasma energy.The obtained results reveal the presence of an extra contribution of approximately 10%based on the considered calculations.

Electromagnetic form factors of neutron and neutral hyperons in the oscillating point of view

Based on the recent precise measurements by the BESIII collaboration for electron–positron annihilation into a neutron and antineutron pair,the effective form factors of the neutron were determined in the time-like region,and it was found that the effective form factors of the neutron are smaller than those of the proton.The effective form factors of the neutron show a periodic behaviour,similar to those of the proton.Here,a comparative analysis forΛ,∑^(0)and■hyperons is performed.Fits of the available data on the effective form factors ofΛ,∑^(0)and■with zero charge show an interesting phenomenon in the oscillating behavior of their effective form factors.However,this will need to be confirmed by future precise experiments.Both theoretical and experimental investigations of this phenomenon can shed light on the reaction mechanisms of the electron–positron annihilation processes.