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 a...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.展开更多
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 m...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.展开更多
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 treatme...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.展开更多
At very high energies, pair production formation (γ + N → e<sup>+</sup>e<sup>-</sup>) exhibits a variety of intriguing properties. Analytically and quantitatively, the formation of Electron-P...At very high energies, pair production formation (γ + N → e<sup>+</sup>e<sup>-</sup>) 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<sup>-</sup>, e<sup>+</sup>) 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<sup>-</sup>, e<sup>+</sup>) 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).展开更多
This is a rotating charge loop model of an electron which explains the electron’s de Broglie base frequency to an accuracy of over 6 decimal places. The model also predicts the magnetic moment of the electron to over...This is a rotating charge loop model of an electron which explains the electron’s de Broglie base frequency to an accuracy of over 6 decimal places. The model also predicts the magnetic moment of the electron to over 6 decimal places and helps explain the transition from a purely electromagnetic photon to a fermion state of matter. The model also explains how charge and spin are conserved in the transition. Finally, this concept might be extended to explain the muon and tau higher energy states of the electron as well.展开更多
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”...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.展开更多
Fermion particle pair production in strong SU（2）-gauge chromoelectric fields is studied using the Boltzmann-Vlasov equation in a classical way. The existence of a preproduction process in a classical description is ...Fermion particle pair production in strong SU（2）-gauge chromoelectric fields is studied using the Boltzmann-Vlasov equation in a classical way. The existence of a preproduction process in a classical description is shown using the distribution evolution of non-Abelian particle production. It is interesting to find that the distribution of the particle number density is centered on two islands and shows a split on the color charge sphere as it evolves, ultimately reaching a steady state that is related to the amplitude and variation of the field.展开更多
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 ima...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.展开更多
In this paper, a method to calculate the vacuum to vacuum transition amplitude in the presence of a non-abelian background field is introduced. The number of non-perturbative quark-antiquark produced per unit time, pe...In this paper, a method to calculate the vacuum to vacuum transition amplitude in the presence of a non-abelian background field is introduced. The number of non-perturbative quark-antiquark produced per unit time, per unit volume and per unit transverse momentum from a given constant chromo-electric field is calculated and its application to quark-gluon plasma is presented.展开更多
An alternative Feynman diagram for electron-positron pair production, in which neutrino and antineutrino are also produced on the same pathway, is introduced here. In the proposed pair production process, a portion of...An alternative Feynman diagram for electron-positron pair production, in which neutrino and antineutrino are also produced on the same pathway, is introduced here. In the proposed pair production process, a portion of the momentum is carried by neutrinos and antineutrinos, allowing the rest of the momentum for the electron-positron pair. Simulations to inspect the proposed pair production process were conducted in this research using the EGS5 code system while modifying its subroutine “PAIR”. Liquid Xenon detector was then positioned in the path of various mono-energetic photon beams ranging from 2.6 to 12 MeV. These simulations were intended to inspect the detectability of the alternative pair production effects on radiation measurements in order to assess the detection conditions. Simulation results provided a comparison between the original pair production process and the proposed pair production process. Spectral results showed that changes in the region around 1 - 2 MeV and in the photopeak region were remarkable, therefore detectable. Further experimental research is recommended based on simulation findings. The alternative pair production process, firstly introduced in this paper, led to production of a larger flux of neutrinos from gamma radiation. This additional neutrino production and its contribution to non-baryonic dark matter are discussed.展开更多
Studies of γγ interactions are performed with the KLOE detector, without tagging of the outgoing e^＋e^-. The data sample is from an integrated luminosity of 240 pb^-1. It was collected at the φ-factory DAONE with...Studies of γγ interactions are performed with the KLOE detector, without tagging of the outgoing e^＋e^-. The data sample is from an integrated luminosity of 240 pb^-1. It was collected at the φ-factory DAONE with e^＋e^- beams colliding at √s ≌1 GeV, below the φ resonance peak. We present preliminary results concerning the observation of the γγ→η process and the evidence for γγ→π^0π^0 production at low π^0π^0 invariant masses.展开更多
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 ...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<sup>-21</sup> 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.展开更多
The discovery of a 125 GeV Higgs boson at the LHC marked a breakthrough in particle physics. The relative lightness of the new particle has inspired consideration of a high-luminosity Circular Electron positron Collid...The discovery of a 125 GeV Higgs boson at the LHC marked a breakthrough in particle physics. The relative lightness of the new particle has inspired consideration of a high-luminosity Circular Electron positron Collider （CEPC） as a Higgs Factory to study the particle＇s properties in an extremely clean environment. Given the high luminosity and high energy of the CEPC, beamstrahlung is one of the most important sources of beam- induced background that might degrade the detector performance. It can introduce even more background to the detector through the consequent electron-positron pair production and hadronic event generation. In this paper, beamstrahlung-induced backgrounds are estimated with both analytical methods and Monte Carlo simulation. Hit density due to detector backgrounds at the first vertex detector layer is found to be -0.2 hits/cm2 per bunch crossing, resulting in a low detector occupancy below 0.5%. Non-ionizing energy loss （NIEL） and total ionizing dose （TID）, representing the radiation damage effects, are estimated to be -1011 1 MeV neq/cm2/yr and --300 kRad/yr, respectively.展开更多
Generation of arbitrarily spin-polarized electron and positron beams has been investigated in the single-shot interaction of high-energy polarized r-photons with an ultraintense asymmetric laser pulse via nonlinear Br...Generation of arbitrarily spin-polarized electron and positron beams has been investigated in the single-shot interaction of high-energy polarized r-photons with an ultraintense asymmetric laser pulse via nonlinear Breit-Wheeler pair production.We develop a fully spin-resolved semi-classical Monte Carlo method to describe the pair creation and polarization.In the considered general setup,there are two sources of the polarization of created pairs:the spin angular momentum transfer from the polarized parent-photons,as well as the asymmetry and polarization of the driving laser field.This allows to develop a highly sensitive tool to control the polarization of created electrons and positrons.Thus,dense GeV lepton beams with average polarization degree up to about 80%,adjustable continuously between the transverse and longitudinal components,can be obtained by our all-optical method with currently achievable laser facilities,which could find an application as injectors of the polarized e^(+)e^(-)collider to search for new physics beyond the Standard Model.展开更多
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 Hadr...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.展开更多
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 scatt...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 e11iptically polarized or evenly circularly polarized one, rather than the usual linear polarization as indicated by previous works interesting unexpected features are a/so discussed briefly. Some insights into pair generation are given and some展开更多
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 p...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.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.11475026,11175023also supported partially by the Open Fund of National Laboratory of Science and Technology on Computational Physics at IAPCM and the Fundamental Research Funds for the Central Universities(FRFCU).
文摘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.
文摘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.
文摘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.
文摘At very high energies, pair production formation (γ + N → e<sup>+</sup>e<sup>-</sup>) 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<sup>-</sup>, e<sup>+</sup>) 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<sup>-</sup>, e<sup>+</sup>) 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).
文摘This is a rotating charge loop model of an electron which explains the electron’s de Broglie base frequency to an accuracy of over 6 decimal places. The model also predicts the magnetic moment of the electron to over 6 decimal places and helps explain the transition from a purely electromagnetic photon to a fermion state of matter. The model also explains how charge and spin are conserved in the transition. Finally, this concept might be extended to explain the muon and tau higher energy states of the electron as well.
文摘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.
文摘Fermion particle pair production in strong SU（2）-gauge chromoelectric fields is studied using the Boltzmann-Vlasov equation in a classical way. The existence of a preproduction process in a classical description is shown using the distribution evolution of non-Abelian particle production. It is interesting to find that the distribution of the particle number density is centered on two islands and shows a split on the color charge sphere as it evolves, ultimately reaching a steady state that is related to the amplitude and variation of the field.
文摘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.
文摘In this paper, a method to calculate the vacuum to vacuum transition amplitude in the presence of a non-abelian background field is introduced. The number of non-perturbative quark-antiquark produced per unit time, per unit volume and per unit transverse momentum from a given constant chromo-electric field is calculated and its application to quark-gluon plasma is presented.
文摘An alternative Feynman diagram for electron-positron pair production, in which neutrino and antineutrino are also produced on the same pathway, is introduced here. In the proposed pair production process, a portion of the momentum is carried by neutrinos and antineutrinos, allowing the rest of the momentum for the electron-positron pair. Simulations to inspect the proposed pair production process were conducted in this research using the EGS5 code system while modifying its subroutine “PAIR”. Liquid Xenon detector was then positioned in the path of various mono-energetic photon beams ranging from 2.6 to 12 MeV. These simulations were intended to inspect the detectability of the alternative pair production effects on radiation measurements in order to assess the detection conditions. Simulation results provided a comparison between the original pair production process and the proposed pair production process. Spectral results showed that changes in the region around 1 - 2 MeV and in the photopeak region were remarkable, therefore detectable. Further experimental research is recommended based on simulation findings. The alternative pair production process, firstly introduced in this paper, led to production of a larger flux of neutrinos from gamma radiation. This additional neutrino production and its contribution to non-baryonic dark matter are discussed.
文摘Studies of γγ interactions are performed with the KLOE detector, without tagging of the outgoing e^＋e^-. The data sample is from an integrated luminosity of 240 pb^-1. It was collected at the φ-factory DAONE with e^＋e^- beams colliding at √s ≌1 GeV, below the φ resonance peak. We present preliminary results concerning the observation of the γγ→η process and the evidence for γγ→π^0π^0 production at low π^0π^0 invariant masses.
文摘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<sup>-21</sup> 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.
基金Supported by CAS/SAFEA International Partnership Program for Creative Research TeamsCAS and IHEP Thousand Talent and Hundred Talent programsgrants from the State Key Laboratory of Nuclear Electronics and Particle Detectors
文摘The discovery of a 125 GeV Higgs boson at the LHC marked a breakthrough in particle physics. The relative lightness of the new particle has inspired consideration of a high-luminosity Circular Electron positron Collider （CEPC） as a Higgs Factory to study the particle＇s properties in an extremely clean environment. Given the high luminosity and high energy of the CEPC, beamstrahlung is one of the most important sources of beam- induced background that might degrade the detector performance. It can introduce even more background to the detector through the consequent electron-positron pair production and hadronic event generation. In this paper, beamstrahlung-induced backgrounds are estimated with both analytical methods and Monte Carlo simulation. Hit density due to detector backgrounds at the first vertex detector layer is found to be -0.2 hits/cm2 per bunch crossing, resulting in a low detector occupancy below 0.5%. Non-ionizing energy loss （NIEL） and total ionizing dose （TID）, representing the radiation damage effects, are estimated to be -1011 1 MeV neq/cm2/yr and --300 kRad/yr, respectively.
基金supported by the National Natural Science Foundation of China(Grants No.12022506,11874295,11875219 and 11905169)the National Key R&D Program of China(Grant No.2019YFA0404900)the Open Fund of the State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)and the foundation of science and technology on plasma physics laboratory(No.JCKYS2021212008)。
文摘Generation of arbitrarily spin-polarized electron and positron beams has been investigated in the single-shot interaction of high-energy polarized r-photons with an ultraintense asymmetric laser pulse via nonlinear Breit-Wheeler pair production.We develop a fully spin-resolved semi-classical Monte Carlo method to describe the pair creation and polarization.In the considered general setup,there are two sources of the polarization of created pairs:the spin angular momentum transfer from the polarized parent-photons,as well as the asymmetry and polarization of the driving laser field.This allows to develop a highly sensitive tool to control the polarization of created electrons and positrons.Thus,dense GeV lepton beams with average polarization degree up to about 80%,adjustable continuously between the transverse and longitudinal components,can be obtained by our all-optical method with currently achievable laser facilities,which could find an application as injectors of the polarized e^(+)e^(-)collider to search for new physics beyond the Standard Model.
基金The work of S.Dulat was supported by the National Natural Science Foundation of China(11965020,11847160)。
文摘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.
基金Supported by the National Natural Science Foundation of China (NNSFC) under Grant Nos. 11175023, 11175020the Fundamental Research Funds for the Central Universities (FRFCU)
文摘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 e11iptically polarized or evenly circularly polarized one, rather than the usual linear polarization as indicated by previous works interesting unexpected features are a/so discussed briefly. Some insights into pair generation are given and some
基金Supported by the National Natural Science Foundation of China (NNSFC) under the grant Nos. 10875015,11175023,10965006,11165014partially by the Fundamental Research Funds for the Central Universities (FRFCU)
文摘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.
