Cylindrical waveguides without end surfaces can serve as two-dimensional resonant cavities. In such cavities the electromagnetic oscillations corresponding to an eigenfrequency can always be taken as TM or TE modes ev...Cylindrical waveguides without end surfaces can serve as two-dimensional resonant cavities. In such cavities the electromagnetic oscillations corresponding to an eigenfrequency can always be taken as TM or TE modes even when the walls have a finite conductivity and the medium is absorptive. This paper obtains analytic solutions to the field equations when the cylinder has a circular cross section. Some nonperturbative conclusions are drawn from the eigenvalue equation. Approximate analytic results for the resonant frequencies are obtained when the absorption of the medium is small and the walls are good conductors. Stability of the eigen modes is discussed. Similar results for the coaxial line are presented.展开更多
The quantum chromodynamics(QCD) coupling αs is the most important parameter for achieving precise QCD predictions. By using the well measured effective coupling α_(s)^(g)1)(Q) defined from the Bjorken sum rules as a...The quantum chromodynamics(QCD) coupling αs is the most important parameter for achieving precise QCD predictions. By using the well measured effective coupling α_(s)^(g)1)(Q) defined from the Bjorken sum rules as a basis, we suggest a novel self-consistency way to fix the αs at all scales: The QCD light-front holographic model is adopted for its infrared behavior, and the fixed-order p QCD prediction under the principle of maximum conformality(PMC) is used for its high-energy behavior. Using the PMC scheme-and-scale independent perturbative series,and by transforming it into the one under the physical V scheme, we observe that a precise αs running behavior in both the perturbative and nonperturbative domains with a smooth transition from small to large scales can be achieved.展开更多
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-...It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.展开更多
We carried out a Padé approximant analysis on a compact factor of the T-matrlx for NN scattering to explore the nonperturbative renormalization prescription in a universal manner. The utilities and virtues for th...We carried out a Padé approximant analysis on a compact factor of the T-matrlx for NN scattering to explore the nonperturbative renormalization prescription in a universal manner. The utilities and virtues for this Padé analysis are discussed.展开更多
Using nonperturbative quantum electrodynamics, we develop a scattering theory for high harmonic generation （HHG）. A transition rate formula for HHG is obtained. Applying this formula, we cal- culate the spectra of h...Using nonperturbative quantum electrodynamics, we develop a scattering theory for high harmonic generation （HHG）. A transition rate formula for HHG is obtained. Applying this formula, we cal- culate the spectra of high harmonics generated from different noble gases shined by strong laser light. We study the cutoff property of the spectra. The data show that the cutoff orders of high harmonics are greater than that predicted by the ＂3.17＂ cutoff law. As a numerical experiment, the data obtained from our repeated calculations support the newly derived theoretical expression of the cutoff law. The cutoff energy of high harmonics described by the new cutoff law, in terms of the ponderomotive energy Up and the ionization potential energy Ip, is 3.34Up 1.83Ip. The higher cutoff orders predicted by this theory are due to the absorption of the extra photons, which participate only the photon-mode up-conversion and do nothing in the photoionization process.展开更多
Using a nonperturbative quantum electrodynamics theory of high-order harmonic generation （HHG）, a scaling law of HHG is established. The scaling law states that when the atomic binding energy Eb, the wavelength ）, ...Using a nonperturbative quantum electrodynamics theory of high-order harmonic generation （HHG）, a scaling law of HHG is established. The scaling law states that when the atomic binding energy Eb, the wavelength ）, and the intensity I of the laser field change simultaneously to kEb, λ/k, and k3I, respectively. The characteristics of the HHG spectrum remain unchanged, while the harmonic yield is enhanced k3 times. That HHG obeys the same scaling law with above-threshold ionization is a solid proof of the fact that the two physical processes have similar physical mechanisms. The variation of integrated harmonic yields is also discussed.展开更多
We investigate a two-photon ionization process in a real hydrogen atom by short and intense chirped laser pulses. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time...We investigate a two-photon ionization process in a real hydrogen atom by short and intense chirped laser pulses. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time-dependent Schrodinger equation with a spectral method. The unperturbed wave functions and electronic energies of the atomic system were found by using an accurate L2 discretisation technique based on the expansion of the wave functions on B-spline functions. We show the efficiency of chirped laser pulses to control the ionization yield and the transfer of the population to the 2p bound state involved in the ionization path.展开更多
A modified method for calculating the nonperturbative quark vacuum condensates from the global color symmetry model is derived. Within this approach it is shown that the treatment of quark vacuum condensates is differ...A modified method for calculating the nonperturbative quark vacuum condensates from the global color symmetry model is derived. Within this approach it is shown that the treatment of quark vacuum condensates is different from that in the previous studies. As a special case we calculate the π and tensor vacuum susceptibilities. A comparison with the results of the other nonperturbative QCD approaches is given.展开更多
Based on QCD sum rule three-point and two-point external field formulas respectively, the vector vacuumsusceptibilities are calculated at the mean-field level in the framework of the global color symmetry model. It is...Based on QCD sum rule three-point and two-point external field formulas respectively, the vector vacuumsusceptibilities are calculated at the mean-field level in the framework of the global color symmetry model. It is shownthat the above two approaches of determination of the vector vacuum susceptibility may lead to different results. Thereason of this contradiction is discussed.展开更多
We study the Schwinger mechanism in the presence of an additional uniformly oriented,weak super Gaussian of integer order 4 N+2.Using the worldline approach,we determine the relevant critical points to compute the lea...We study the Schwinger mechanism in the presence of an additional uniformly oriented,weak super Gaussian of integer order 4 N+2.Using the worldline approach,we determine the relevant critical points to compute the leading order exponential factor analytically.We show that increasing the parameter N gives rise to a strong dynamical enhancement.For N=2,this effect turns out to be larger compared to a weak contribution of the Sauter type.For higher orders,specifically,for the rectangular barrier limit,i.e.N→∞,we approach the Lorentzian case as an upper bound.Although the mentioned backgrounds significantly differ in Minkowski spacetime,we show that the found coincidence applies due to identical reflection points in the Euclidean instanton plane.In addition,we also treat the background in perturbation theory following recent ideas.By doing so,we show that the parameter N determines whether the weak contribution behaves perturbatively or nonperturbatively with respect to the field strength ratio,and,hence,reveals an interesting dependence on the background shape.In particular,we show that for backgrounds,for which higher orders in the field strength ratio turn out to be relevant,a proposed integral condition is not fulfilled.In view of these findings,the latter may serve as an indicator for the necessity for higher-order contributions.展开更多
We illustrate via the sunset diagram that dimensional regularization ‘deforms' the nonlocal contentsof multi-loop diagrams with its equivalence to cutoff regularization scheme recovered only after sub-divergence ...We illustrate via the sunset diagram that dimensional regularization ‘deforms' the nonlocal contentsof multi-loop diagrams with its equivalence to cutoff regularization scheme recovered only after sub-divergence wassubtracted. Then we employed a differential equation approach for calculating loop diagrams to verify that dimensionalare argued especially in nonperturbativc perspective.展开更多
Based on a modified version of the global color symmetry model,the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculat...Based on a modified version of the global color symmetry model,the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculated beyond the vacuum saturation approximation.Comparison with the previous estimations has been given.展开更多
In this work, we calculate the mass spectrum of doubly heavy baryons with the diquaxk model in terms of the QCD sum rules. The interpolating currents are composed of a heavy diquaxk field and a light quark field. Cont...In this work, we calculate the mass spectrum of doubly heavy baryons with the diquaxk model in terms of the QCD sum rules. The interpolating currents are composed of a heavy diquaxk field and a light quark field. Contributions of the operators up to dimension six are taken into account in the operator product expansion. Within a reasonable error tolerance, our numerical results axe compatible with other theoretical predictions. This indicates that the diquaxk picture reflects the reality and is applicable to the study of doubly heavy baryons.展开更多
In order to investigate a complicated physical system, it is convenient to consider a simple, easy to solve model, which is chosen to reflect as much physics as possible of the original system, as an ideal approximati...In order to investigate a complicated physical system, it is convenient to consider a simple, easy to solve model, which is chosen to reflect as much physics as possible of the original system, as an ideal approximation. Motivated by this fundamental idea, we propose a novel asymptotic method, the nonsensitive homotopy-Pade approach. In this method, homotopy relations are constructed to link the original system with an ideal, solvable model. An artificial homotopy parameter is introduced to the homotopy relations as the normal perturbation parameter to generate the perturbation series, and is used to implement the Padd approximation. Meanwhile, some other auxiliary nonperturbative parameters, which are used to control the convergence of the perturbation series, are inserted to the approximants, and are fixed via the principle of minimal sensitivity. The method is used to study the eigenvalue problem of the quantum anharmonic oscillators. Highly accurate numerical results show its validity. Possible further studies on this method are also briefly discussed.展开更多
We illustrate via the sunset diagram that dimensional regularization 'deforms' the nonlocal contents of multi-loop diagrams with its equivalence to cutoff regularization scheme recovered only after sub-diverge...We illustrate via the sunset diagram that dimensional regularization 'deforms' the nonlocal contents of multi-loop diagrams with its equivalence to cutoff regularization scheme recovered only after sub-divergence was subtracted. Then we employed a differential equation approach for calculating loop diagrams to verify that dimensional regularization deforms the 'low energy' contents before subtraction. The virtues of the differential equation approach are argued especially in nonperturbative perspective.展开更多
We numerically investigate the ionization mechanism in a real hydrogen atom under intense fem to second chirped laser pulses. The central carrier frequency of the pulses is chosen to be 6.2 eV (λ = 200 nm), which cor...We numerically investigate the ionization mechanism in a real hydrogen atom under intense fem to second chirped laser pulses. The central carrier frequency of the pulses is chosen to be 6.2 eV (λ = 200 nm), which corresponds to the fourth-harmonic of the Ti:Sapphire laser. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time-dependent Schrodinger equation with a spectral method. The unperturbed wave functions and electronic energies of the atomic system were found by using an L2 discretization technique based on the expansion of the wave functions on B-spline functions. The presented results of kinetic energy spectra of the emitted electrons show the sensitivity of the ionization process to the chirp parameter. Particular attention is paid to the important role of the excited bound states involved in the ionization paths.展开更多
Crystalline undulator radiation(CUR)is emitted by charged particles channeling through a periodically bent crystal.We show that entangled high-energy photons of the order of 100 MeV can be generated from CUR and obtai...Crystalline undulator radiation(CUR)is emitted by charged particles channeling through a periodically bent crystal.We show that entangled high-energy photons of the order of 100 MeV can be generated from CUR and obtain the quantum entanglement properties of the double-photon emission of CUR with a nonperturbative quantum field theory.展开更多
The currently well accepted cutoff law for laser induced high harmonic spectra predicts the cutoff energy as a linear combination of two interaction energies, the ponderomotive energy Up and the atomic biding energy I...The currently well accepted cutoff law for laser induced high harmonic spectra predicts the cutoff energy as a linear combination of two interaction energies, the ponderomotive energy Up and the atomic biding energy Ip, with coefficients 3.17 and 1.32, respectively. Even though, this law has been there for twenty years or so, the background information for these two constants, such as how they relate to fundamental physics and mathematics constants, is still unknown. This simple fact, keeps this cutoff law remaining as an empirical one. Based on the cutoff property of Bessel functions and the Einstein photoelectric law in the multiphoton case, we show these two coefficients are algebraic constants, 9 - 4√2 ≈ 3.34 and 2√2-1≈1.83, respectively. A recent spectra calculation and an experimental measurement support the new cutoff law.展开更多
We are reporting a theoretical prediction： The photoelectrons forming above-threshold-ionization （ATI） peaks emit both even and odd harmonics. These harmonics exhibit plateau and cut-off features similar to those o...We are reporting a theoretical prediction： The photoelectrons forming above-threshold-ionization （ATI） peaks emit both even and odd harmonics. These harmonics exhibit plateau and cut-off features similar to those odd-only harmonics observed in ATI experiments.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 10675174)
文摘Cylindrical waveguides without end surfaces can serve as two-dimensional resonant cavities. In such cavities the electromagnetic oscillations corresponding to an eigenfrequency can always be taken as TM or TE modes even when the walls have a finite conductivity and the medium is absorptive. This paper obtains analytic solutions to the field equations when the cylinder has a circular cross section. Some nonperturbative conclusions are drawn from the eigenvalue equation. Approximate analytic results for the resonant frequencies are obtained when the absorption of the medium is small and the walls are good conductors. Stability of the eigen modes is discussed. Similar results for the coaxial line are presented.
基金supported in part by the Chongqing Graduate Research and Innovation Foundation (Grant Nos. CYB21045 and ydstd1912)the National Natural Science Foundation of China (Grant Nos. 11905056, 12175025, and 12147102)the Fundamental Research Funds for the Central Universities (Grant No. 2020CQJQYZ003)。
文摘The quantum chromodynamics(QCD) coupling αs is the most important parameter for achieving precise QCD predictions. By using the well measured effective coupling α_(s)^(g)1)(Q) defined from the Bjorken sum rules as a basis, we suggest a novel self-consistency way to fix the αs at all scales: The QCD light-front holographic model is adopted for its infrared behavior, and the fixed-order p QCD prediction under the principle of maximum conformality(PMC) is used for its high-energy behavior. Using the PMC scheme-and-scale independent perturbative series,and by transforming it into the one under the physical V scheme, we observe that a precise αs running behavior in both the perturbative and nonperturbative domains with a smooth transition from small to large scales can be achieved.
文摘It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
基金The project supported in part by National Natural Science Foundation of China under Grant No. 10205004 .Acknowledgments The authors are grateful to Dr. E. Epelbaum for helpful communications. J.F. Yang is grateful to Prof. B.A. Kniehl for his hospitality at the II. Institute for Theoretical Physics of Hamburg University where part of this work was done.
文摘We carried out a Padé approximant analysis on a compact factor of the T-matrlx for NN scattering to explore the nonperturbative renormalization prescription in a universal manner. The utilities and virtues for this Padé analysis are discussed.
文摘Using nonperturbative quantum electrodynamics, we develop a scattering theory for high harmonic generation （HHG）. A transition rate formula for HHG is obtained. Applying this formula, we cal- culate the spectra of high harmonics generated from different noble gases shined by strong laser light. We study the cutoff property of the spectra. The data show that the cutoff orders of high harmonics are greater than that predicted by the ＂3.17＂ cutoff law. As a numerical experiment, the data obtained from our repeated calculations support the newly derived theoretical expression of the cutoff law. The cutoff energy of high harmonics described by the new cutoff law, in terms of the ponderomotive energy Up and the ionization potential energy Ip, is 3.34Up 1.83Ip. The higher cutoff orders predicted by this theory are due to the absorption of the extra photons, which participate only the photon-mode up-conversion and do nothing in the photoionization process.
基金supported by the National Natural Science Foundation of China (Grant Nos.10774153 and 61078080)the National Basic Research Program of China (Grant Nos.2010CB923203 and 2011CB808103)
文摘Using a nonperturbative quantum electrodynamics theory of high-order harmonic generation （HHG）, a scaling law of HHG is established. The scaling law states that when the atomic binding energy Eb, the wavelength ）, and the intensity I of the laser field change simultaneously to kEb, λ/k, and k3I, respectively. The characteristics of the HHG spectrum remain unchanged, while the harmonic yield is enhanced k3 times. That HHG obeys the same scaling law with above-threshold ionization is a solid proof of the fact that the two physical processes have similar physical mechanisms. The variation of integrated harmonic yields is also discussed.
文摘We investigate a two-photon ionization process in a real hydrogen atom by short and intense chirped laser pulses. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time-dependent Schrodinger equation with a spectral method. The unperturbed wave functions and electronic energies of the atomic system were found by using an accurate L2 discretisation technique based on the expansion of the wave functions on B-spline functions. We show the efficiency of chirped laser pulses to control the ionization yield and the transfer of the population to the 2p bound state involved in the ionization path.
文摘A modified method for calculating the nonperturbative quark vacuum condensates from the global color symmetry model is derived. Within this approach it is shown that the treatment of quark vacuum condensates is different from that in the previous studies. As a special case we calculate the π and tensor vacuum susceptibilities. A comparison with the results of the other nonperturbative QCD approaches is given.
文摘Based on QCD sum rule three-point and two-point external field formulas respectively, the vector vacuumsusceptibilities are calculated at the mean-field level in the framework of the global color symmetry model. It is shownthat the above two approaches of determination of the vector vacuum susceptibility may lead to different results. Thereason of this contradiction is discussed.
基金the support of the Collaborative Research Center SFB 676 of the DFG.
文摘We study the Schwinger mechanism in the presence of an additional uniformly oriented,weak super Gaussian of integer order 4 N+2.Using the worldline approach,we determine the relevant critical points to compute the leading order exponential factor analytically.We show that increasing the parameter N gives rise to a strong dynamical enhancement.For N=2,this effect turns out to be larger compared to a weak contribution of the Sauter type.For higher orders,specifically,for the rectangular barrier limit,i.e.N→∞,we approach the Lorentzian case as an upper bound.Although the mentioned backgrounds significantly differ in Minkowski spacetime,we show that the found coincidence applies due to identical reflection points in the Euclidean instanton plane.In addition,we also treat the background in perturbation theory following recent ideas.By doing so,we show that the parameter N determines whether the weak contribution behaves perturbatively or nonperturbatively with respect to the field strength ratio,and,hence,reveals an interesting dependence on the background shape.In particular,we show that for backgrounds,for which higher orders in the field strength ratio turn out to be relevant,a proposed integral condition is not fulfilled.In view of these findings,the latter may serve as an indicator for the necessity for higher-order contributions.
基金The project supported in part by National Natural Science Foundation of China under Grant No. 10075020
文摘We illustrate via the sunset diagram that dimensional regularization ‘deforms' the nonlocal contentsof multi-loop diagrams with its equivalence to cutoff regularization scheme recovered only after sub-divergence wassubtracted. Then we employed a differential equation approach for calculating loop diagrams to verify that dimensionalare argued especially in nonperturbativc perspective.
文摘Based on a modified version of the global color symmetry model,the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculated beyond the vacuum saturation approximation.Comparison with the previous estimations has been given.
基金Supported by the National Natural Science Foundation of China (NSFC)by the CAS Key Projects KJCX2-yw-N29 and H92A0200S2
文摘In this work, we calculate the mass spectrum of doubly heavy baryons with the diquaxk model in terms of the QCD sum rules. The interpolating currents are composed of a heavy diquaxk field and a light quark field. Contributions of the operators up to dimension six are taken into account in the operator product expansion. Within a reasonable error tolerance, our numerical results axe compatible with other theoretical predictions. This indicates that the diquaxk picture reflects the reality and is applicable to the study of doubly heavy baryons.
基金Supported by the National Natural Science Foundations of China under Grant Nos.10735030,10475055,10675065 and 90503006National Basic Research Program of China (973 Program) under Grant No.2007CB814800+2 种基金Program for Changjiang Scholars and Innovative Research Team (IRT0734)the Research Fund of Postdoctoral of China under Grant No.20070410727Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20070248120
文摘In order to investigate a complicated physical system, it is convenient to consider a simple, easy to solve model, which is chosen to reflect as much physics as possible of the original system, as an ideal approximation. Motivated by this fundamental idea, we propose a novel asymptotic method, the nonsensitive homotopy-Pade approach. In this method, homotopy relations are constructed to link the original system with an ideal, solvable model. An artificial homotopy parameter is introduced to the homotopy relations as the normal perturbation parameter to generate the perturbation series, and is used to implement the Padd approximation. Meanwhile, some other auxiliary nonperturbative parameters, which are used to control the convergence of the perturbation series, are inserted to the approximants, and are fixed via the principle of minimal sensitivity. The method is used to study the eigenvalue problem of the quantum anharmonic oscillators. Highly accurate numerical results show its validity. Possible further studies on this method are also briefly discussed.
文摘We illustrate via the sunset diagram that dimensional regularization 'deforms' the nonlocal contents of multi-loop diagrams with its equivalence to cutoff regularization scheme recovered only after sub-divergence was subtracted. Then we employed a differential equation approach for calculating loop diagrams to verify that dimensional regularization deforms the 'low energy' contents before subtraction. The virtues of the differential equation approach are argued especially in nonperturbative perspective.
文摘We numerically investigate the ionization mechanism in a real hydrogen atom under intense fem to second chirped laser pulses. The central carrier frequency of the pulses is chosen to be 6.2 eV (λ = 200 nm), which corresponds to the fourth-harmonic of the Ti:Sapphire laser. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time-dependent Schrodinger equation with a spectral method. The unperturbed wave functions and electronic energies of the atomic system were found by using an L2 discretization technique based on the expansion of the wave functions on B-spline functions. The presented results of kinetic energy spectra of the emitted electrons show the sensitivity of the ionization process to the chirp parameter. Particular attention is paid to the important role of the excited bound states involved in the ionization paths.
基金National Natural Science Foundation of China(12174009,11974031,12174011,12234002,92250303)Innovation Program for Quantum Science and Technology(2021ZD0301702)+2 种基金Beijing Natural Science Foundation(Z220008)Natural Science Foundation of Jiangsu Province(BK20232002)National Key Research and Development Program of China(2023YFA1406801).
文摘Crystalline undulator radiation(CUR)is emitted by charged particles channeling through a periodically bent crystal.We show that entangled high-energy photons of the order of 100 MeV can be generated from CUR and obtain the quantum entanglement properties of the double-photon emission of CUR with a nonperturbative quantum field theory.
文摘The currently well accepted cutoff law for laser induced high harmonic spectra predicts the cutoff energy as a linear combination of two interaction energies, the ponderomotive energy Up and the atomic biding energy Ip, with coefficients 3.17 and 1.32, respectively. Even though, this law has been there for twenty years or so, the background information for these two constants, such as how they relate to fundamental physics and mathematics constants, is still unknown. This simple fact, keeps this cutoff law remaining as an empirical one. Based on the cutoff property of Bessel functions and the Einstein photoelectric law in the multiphoton case, we show these two coefficients are algebraic constants, 9 - 4√2 ≈ 3.34 and 2√2-1≈1.83, respectively. A recent spectra calculation and an experimental measurement support the new cutoff law.
基金Acknowledgements This work was supported in part by the National Natural Science Foundation of China （Grant Nos. 11174304 and 61078080）, the National Basic Research Program of China （973 Program） （Grant Nos. 2010CB923203 and 2011CB808103）, and also the National Natural Science Foundation of China under Grant No. 11172302.
文摘We are reporting a theoretical prediction： The photoelectrons forming above-threshold-ionization （ATI） peaks emit both even and odd harmonics. These harmonics exhibit plateau and cut-off features similar to those odd-only harmonics observed in ATI experiments.
