Pair Production in Chromoelectric Field with Back Reaction

Massless quark pair production in SU(2) gauge chromoelectric field is investigated by solving the Wigner function with back reaction. The temporal evolution of specific field and its current are obtained self consistently. For the quark distribution function, both its time and momentum dependence are studied. In particular, some interesting phenomena are found, for example, the more abundant symmetry or/and antisymmetry characteristics, the existence of the attractive basin structure and the existence of the momentum "gap" in the quark distribution and so on. All the phenomena are associated with the quark-gluon plasma oscillation, which due to the back reaction effect. The study and analysis qualitatively about the components of the Wigner function are expected to be helpful to deepen the understanding of the QCD vacuum.     

Pair Production in a Uniform Electric Field

We study the Klein-Gordon field coupled with an external uniform vector potential. We compute pair production in a finite time t using the semiclassical approximation, and show that, after the interaction of the Klein-Gordon field with the external potential, when 0 the average number of produced pairs is zero. There is agreement with the classical limit because the classical limit involves no production of pairs. We compared our results with those of Schwinger. Finally we saw that the random variable N(t)= net number of pairs produced at time t is in the semiclassical limit a stochastic Poisson process.     

Electron-Positron Pair Production in an Arbitrary Polarized Ultrastrong Laser Field

Electron-positron pair production in an arbitrary polarized ultrastrong laser field is investigated in the first order perturbation approximation in which the Volkov states are used for convenient calculation of scattering amplitude and cross section. It is found surprisingly that the optimal pair production depends strongly on the polarization. For some cases of field parameters, the optimal field is elliptically polarized or evenly circularly polarized one, rather than the usual linear polarization as indicated by previous works. Some insights into pair generation are given and some interesting unexpected features are also discussed briefly.     

Electron-Positron Pair Production in an Arbitrary Polarized Ultrastrong Laser Field

Electron-positron pair production in an arbitrary polarized ultrastrong laser field is investigated in the first order perturbation approximation in which the Volkov states are used for convenient calculation of scattering amplitude and cross section. It is found surprisingly that the optimal pair production depends strongly on the polarization. For some cases of field parameters, the optimal field is elliptically polarized or evenly circularly polarized one, rather than the usual linear polarization as indicated by previous works. Some insights into pair generation are given and some interesting unexpected features are also discussed briefly.     

Electron-Positron Pair Production in a Strong Laser Field Enhanced by an Assisted High Frequency Weak Field

Electron-positron pair production in a strong laser field enhanced by an assisted high frequency weak field is investigated by solving the quantum Vlasov equation.The average and residual pair number densities are obtained for sinusoid electric field and it is found that the high frequency assisted weak field will enhance pair production significantly.There exists an optimal frequency of assisted field that makes the pair production number density get a maximum one,which is a few orders of higher than that without assisted field.We also discuss the other possible assisted fields.     

Chromoelectric and chromomagnetic effects in the confinement of gluons

Results are presented from a new variational calculation of quantized SU(3) Yang-Mills fields. The Hamiltonian formalism is applied to the continuum theory, with a truncated momentum expansion in a finite volume, using the Coulomb gauge. The relative importance of electrical and magnetic effects is examined, using an improved treatment of paramagnetic effects. The results depend on the value of the interaction constant, with a transition at0.4. For>0, there is a mass gap between the first excited state and the vacuum state, arising from properties of the Faddeev-Popov determinant. For0·4, properties of the Coulomb energy operator lead to a second mass gap between the first and the higher excited states.This work was supported by the U.S. Dept. of Energy under contract No. DE-AC 02-76 ER-03066. Support for computation on the CRAY X-MP/48 at the Pittsburgh Supercomputing Center has been provided by the NSF through grant No. PSCA-195, and by Cray Research, Inc. through grant No. CRI-8703. The calculation ofF andG _KL was done in collaboration with K. C. Wang. J. Mahdavi assisted with programming.     

Neutralino Pair Production at Proton-Proton Collider

We investigated the Drell-Yan process of the light neutralino pair (i, j = 1, 2) productions at hadron colliders. We studied the dependence of the coupling properties of two light neutralinos on, three SUSY Lagrangian parameters M₁, M₂ and μ, and find that the production rate of pair will be dominated by the Higgsino-like couplings under the conditions p << M₂ and μ～M₁.     

Squark Pair Production at Muon Colliders in the MSSM with CP Violation

We study the pair production of scalar quark in a muon collider within the MSSM with CP violation. We show that including the CP phases can strongly affect the cross section of the process: \(\mu^{+}\mu^{-}\rightarrow \tilde{q}_{i}\bar{\tilde{q}}_{j}\). This could have an important impact on the search for squarks and the determination of the MSSM parameters at future colliders.     

Back Reaction of Charged Black Hole

The existence of the Hawking radiation of theblack hole surely affects spacetime. Here, using athermodynamic approach, to avoid the difficulty offinding the energy-momentum tensor, we obtainexpressions for the energy and entropy of theReissner–Nordstrom black hole (RNBH), and providea better way of solving the backreaction of more complexblack holes.     

Analytical Study of Pair Production Rate from Vacuum in an Elliptic Polarized Field by a Two-Level Transition Technique

Electron-positron pair production rate created from vacuum in the presence of an elliptically polarized laser field is investigated.By applying the technique of two level transition amplitude,a routine for obtaining pair production rate is presented,and approximate analytical expressions are given both for the low frequency strong field regime and the high frequency weak field regime.We found that for an elliptically polarized field,the electron-positron pair production rate decrease when the elliptic eccentricity increase in the high frequency weak field regime,however,in the low frequency strong field regime,there is almost the same electron-positron pair production rate as in the constant electric field case.     

Charged Higgs Boson Pair Production via Gluon-Gluon Collisions in MSSM with CP Violation

The CP-violating effects to the subprocess gg→H⁺H^- are studied in the mSUGRA scenario at the CERN large hadron collider, by taking into account the experimental bounds of electron and neutron electric dipole moments. The CP-violating effects in this process are related to the complex phases of μ and A_f in the mSUGRA scenario. In our calculation we consider small CP phases of μ and A_f and neglect the effects of neutral Higgs boson mixing. In this case the CP effects to the process mainly come from the complex couplings of Higgs-squark-squark. We find a strong dependence of charged Higgs boson pair production rate on the complex couplings in the parameter space of minimal supersymmetric standard model.     

Charged Higgs Boson Pair Production via Gluon-Gluon Collisions in MSSM with CP Violation

The CP-violating effects to the subprocess gg → H H- are studied in the mSUGRA scenario at the CERN large hadron collider, by taking into account the experimental bounds of electron and neutron electric dipole moments.The CP-violating effects in this process are related to the complex phases ofμ and Af in the mSUGRA scenario. In our calculation we consider smallCP phases ofμ and Af and neglect the effects of neutral Higgs boson mixing. In this case the CP effects to the process mainly come from the complex couplings of Higgs-squark-squark. We find a strong dependence of charged Higgs boson pair production rate on the complex couplings in the parameter space of minimal supersymmetric standard model``     

Numerical Computation of Dynamical Schwinger-like Pair Production in Graphene

Russian Physics Journal - The density of electron-hole pairs produced in a graphene sample immersed in a homogeneous time-dependent electric field is evaluated. Because low energy charge carriers...     

Electron-Positron Pair Production in Strong Fields Characterized by Conversion Energy

It is demonstrated that the production mechanism of a pair which is produced from vacuum under an external field can be characterized by its conversion energy, a quantity defined as total mass-energy of this pair. The value of this quantity is checked with quantum field theoretical simulations for several field configurations and it is found that conversion energy can show all the production channels and give the yields of each channel specifically. We detect signatures of effective mass, combination of different photons as well as dynamically assisted Schwinger mechanism and represented more features of these processes in the view of conversion energy.     

SUSY-QCD Effects in Top Quark Pair Production in Association with a Gluon at the ILC

Given the null results of searches for new physics at the LHC,we investigate the one-loop effects SUSY QCD in the process e~+e~-→tg at the ILC in Minimal Supersymmetric Standard Model(MSSM).We find that the relative SUSY-QCD corrections to the cross section of e~+e~-→ tg can maximally reach 6.5%(3.2%) at the ILC with (1/2)s= 1000 GeV when m__1= 313.4 GeV and m_g =500(1500) GeV.     

SUSY-QCD Effects in Top Quark Pair Production in Association with a Gluon at the ILC

Given the null results of searches for new physics at the LHC, we investigate the one-loop effects SUSY QCD in the process e⁺e^-→ttg at the ILC in Minimal Supersymmetric Standard Model (MSSM). We find that the relative SUSY-QCD corrections to the cross section of e⁺e^-→ttg can maximally reach 6.5%(3.2%) at the ILC with √s=1000 GeV when m=313:4 GeV and m=500(1500) GeV.