The massless dark photon~γ can only interact with the Standard Model(SM)sector via higherdimensional operators.In this letter,we investigate its production associated with the ordinary photonγfrom the lepton flavor ...The massless dark photon~γ can only interact with the Standard Model(SM)sector via higherdimensional operators.In this letter,we investigate its production associated with the ordinary photonγfrom the lepton flavor violation(LFV)process l_(i)→l_(j)γγ and di-production from the LFV process l_(i)→l_(j)γγ induced by dipole operators.Comparing the obtained numerical results with the corresponding experimental measurements,we obtain the constraints on the effective couplings of γ with the SM charged leptons.The upper limit of the effective coupling|DLμe|2+|DRμe|2coming from the process μ→e~γγis looser than the processμ→eγ by about one order of magnitude.展开更多
A systematic rigorous analysis of both massless fermion fields in the mass spectra of superstring theory is carried out. Our interest is in dynamical aspects of these fields. An explicit novel expression for the propa...A systematic rigorous analysis of both massless fermion fields in the mass spectra of superstring theory is carried out. Our interest is in dynamical aspects of these fields. An explicit novel expression for the propagator of the massless Rarita-Schwinger field (the gravitino), in the mass spectrum involving massless fermions in superstring theory in 10 dimensions, is derived. The analysis is carried in the presence of a non-constrained external source so that the full expression of the propagator emerges. The number of associated degrees of freedom is also obtained. We work in a Coulomb-like gauge. The massless Dirac field (the dilatino), the other massless fermion field in the mass spectra of superstring theory in 10 dimensions, is first investigated to this end.展开更多
Applying perturbative QCD, we study the process Bc → Dsγ in the technicolor with a massless scalar doublet model (TCMLSM). There are mainly two mechanisms contributing to the Bc → D*sγ process. One proceeds throug...Applying perturbative QCD, we study the process Bc → Dsγ in the technicolor with a massless scalar doublet model (TCMLSM). There are mainly two mechanisms contributing to the Bc → D*sγ process. One proceeds through the short distance b → sγ transition and the other through weak annihilation accompanied by a photon emission.We find that, compared with the standard model, the modification of Bc → D*sγ from πρ (the physical pions in the TCMLSM) is so small that can be neglected for the allowed mass ofπρ. The weak-annihilation contribution is found to be about one order larger than that of the electromagnetic penguin diagrams.展开更多
Recently, considerable progress has been made in understanding the early universe by loop quantum cosmology. Modesto et al. investigated the loop quantum black hole （LQBH）using improved semiclassical analysis and th...Recently, considerable progress has been made in understanding the early universe by loop quantum cosmology. Modesto et al. investigated the loop quantum black hole （LQBH）using improved semiclassical analysis and they found that the LQBH has two horizons, an event horizon and a Cauchy horizon, just like the Reissner-NordstrSm black hole. This paper focuses on the dynamical evolution of a massless scalar wave in the LQBH background. By investigating the relation between the complex frequencies of the massless scalar field and the LQBH parameters using the numerical method, we find that the polymeric parameter P makes the massless scalar field decay more quickly and makes the ground scalar wave oscillate slowly. However, the polymeric parameter P causes the frequency of the high harmonic massless scalar wave to shift according to its value. We also find that the loop quantum gravity area gap parameter a0 causes the massless scalar field to decay more slowly and makes the period of the massless scalar field wave become longer. In the complex ω plane, the frequency curves move counterclockwise when the polymeric parameter P increases and this spiral effect is more obvious for a higher harmonic scalar wave.展开更多
By using the partial wave method, we investigate the absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence. We obtained the expression of absorption cross sectionσabs（ω）=...By using the partial wave method, we investigate the absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence. We obtained the expression of absorption cross sectionσabs（ω）=π/ω^2 ∑ t=0^∞ （2l＋1）｜Tωl（ω）｜^2=π/ω^2∑ t=0^∞（2l＋1）Гωl（ω）.Then we numerically carry out the absorption cross section and we find that the larger the angular momentum quantum number 1 is, the smaller the corresponding maximum value of the partial absorption cross section is, and that the total absorption cross section tends to the geometric-optical limit σhfabs≈ bc^2. We also find that higher value of ωq （state abs parameter of quintessence） corresponds to the higher value of absorption cross section gabs.展开更多
We study the massless scalar quasinormal frequencies of an asymptotically flat static and spherically symmetric black hole with a nonzero magnetic charge in four-dimensional extended scalar-tensor-Gauss-Bonnet theory....We study the massless scalar quasinormal frequencies of an asymptotically flat static and spherically symmetric black hole with a nonzero magnetic charge in four-dimensional extended scalar-tensor-Gauss-Bonnet theory. The results show that the real part of the quasinormal frequency becomes larger and the imaginary part becomes smaller with increasing the magnetic charge or the angular harmonic index. The existence of magnetic charges will reduce the damping of scalar perturbation, but increase the frequency. We also study the absorption crosssection of the scalar field in this black hole. We find that its curve will become lower as the magnetic charge increases, i.e. the magnetic charge will weaken the absorption capacity of the black hole. Meanwhile, the high-frequency limit of the total absorption cross-section is just the area of black hole shadow.展开更多
The Dirac–Weyl equation characterized quasi-particles in the T3 lattice are studied under external magnetic field using the generalized uncertainty principle(GUP). The energy spectrum of the quasi-particles is found ...The Dirac–Weyl equation characterized quasi-particles in the T3 lattice are studied under external magnetic field using the generalized uncertainty principle(GUP). The energy spectrum of the quasi-particles is found by the Nikiforov–Uvarov method. Based on the energy spectrum obtained, the thermodynamic properties are given, and the influence of the GUP on the statistical properties of systems is discussed. The results show that the energy and thermodynamic functions of massless Dirac–Weyl fermions in the T3 lattice depend on the variation of the GUP parameter.展开更多
This article considers a static and spherical black hole(BH)in f(Q)gravity.f(Q)gravity is the extension of symmetric teleparallel general relativity,where both curvature and torsion are vanishing and gravity is descri...This article considers a static and spherical black hole(BH)in f(Q)gravity.f(Q)gravity is the extension of symmetric teleparallel general relativity,where both curvature and torsion are vanishing and gravity is described by nonmetricity.In this study,we investigate the possible implications of quasinormal mode(QNM)modified Hawking spectra and deflection angles generated by the model.The Wentzel–Kramers–Brillouin method is used to solve the equations of motion for massless Dirac perturbation fields and explore the impact of the nonmetricity parameter(Q_(0)).Based on the QNM computation,we can ensure that the BH is stable against massless Dirac perturbations and as Q_(0)increases the oscillatory frequency of the mode decreases.We then discuss the weak deflection angle in the weak field limit approximation.We compute the deflection angle up to the fourth order of approximation and show how the nonmetricity parameter affects it.We find that the Q_(0)parameter reduces the deflection angle.展开更多
In our previous work [Chin. Phys. Lett. 35（2018） 010410], the quasinormal modes of massless scalar field perturbation in a noncommutative-geometry-inspired Schwarzschild black hole spacetime are studied using the th...In our previous work [Chin. Phys. Lett. 35（2018） 010410], the quasinormal modes of massless scalar field perturbation in a noncommutative-geometry-inspired Schwarzschild black hole spacetime are studied using the third-order Wentzel–Kramers–Brillouin approximative approach. In this study, we extend the work to the cases of gravitational, electromagnetic and massless Dirac perturbations. The result further confirms that the noncommutative parameter plays an important role for the quasinormal frequencies.展开更多
The Casimir effect has been studied for various quantum fields in both fiat and curved spacetimes. As a further step along this line, we provide an explicit derivation of Casimlr effect for massless spin-3/2 field wit...The Casimir effect has been studied for various quantum fields in both fiat and curved spacetimes. As a further step along this line, we provide an explicit derivation of Casimlr effect for massless spin-3/2 field with periodic boundary condition imposed in four-dimensional Minkowski spacetime. The corresponding results with Dirichlet and Neumann boundary conditions are also discussed.展开更多
The Daya Bay Collaboration has discovered that approximately 6.0%of active neutrinos were missing from the nuclear reaction container.This finding has led to a reinterpretation of the three known types of neutrinos.In...The Daya Bay Collaboration has discovered that approximately 6.0%of active neutrinos were missing from the nuclear reaction container.This finding has led to a reinterpretation of the three known types of neutrinos.In this paper,we present an analysis based on deductive reasoning,proposing that neutrinos are massless in the longitudinal direction(referred to as“longitudinal mass-less”).This insight contributes to the broader body of literature on the subject.Additionally,our work resolves the long-standing mystery of CP conservation in strong interactions.Using advanced physical mathematics,we derive a sig-nificant result:the transformation between the third type of neutrino and pho-tons or gravitons.We express the probability of this transformation in quan-tum mechanics using sinc functions which arise from interference effects,providing analytical solutions.Furthermore,considering the mass constraints imposed by the seesaw mechanism—referred to here as the“compete mecha-nism”(a generalized seesaw model)—we argue that the actual phase 4π of CP violation precisely answers the fundamental question at hand.展开更多
Simulating the nature of quantum fields in diverse spacetime backgrounds offers valuable insights for the fundamental comprehension of quantum mechanics and general relativity.Here we introduce a novel method for mapp...Simulating the nature of quantum fields in diverse spacetime backgrounds offers valuable insights for the fundamental comprehension of quantum mechanics and general relativity.Here we introduce a novel method for mapping the massless Dirac equation in 1+1D curved spacetime to a controllable quantum simulation model,applicable to various observers'perspectives.We perform numerical simulations of Simpson spacetime and calculate tunneling rates in Painlevéand Schwarzschild coordinates,which align closely with theoretical predictions of Hawking radiation.Additionally,we show the transition of Simpson spacetime from a regular black hole to a wormhole as the parameter“a>r_(s)”.This method facilitates the study of spacetime from various coordinate perspectives(observers),providing deeper insights and understanding.展开更多
Physicists have been interested in quantization of spinor and vector free fields in 4-dimensional de Sitter space-time, in ambient space notation. The Gupta-Bleuler formalism has been extensively applied to the quanti...Physicists have been interested in quantization of spinor and vector free fields in 4-dimensional de Sitter space-time, in ambient space notation. The Gupta-Bleuler formalism has been extensively applied to the quantization of gauge invariant theories. The field equation of the massless spin-3/2 fields is gauge invariant in de Sitter space. In this paper, we study the quantization of massless spin-3/2 gauge fields in de Sitter space-time by the Gupta-Bleuler formalism. This triplet carries an indecomposable representation of the de Sitter group.展开更多
We study the scattering of massless Dirac fermions by Schwarzschild and Reissner-Nordstrm black holes. This is done by applying partial wave analysis to the scattering modes obtained after solving the massless Dirac e...We study the scattering of massless Dirac fermions by Schwarzschild and Reissner-Nordstrm black holes. This is done by applying partial wave analysis to the scattering modes obtained after solving the massless Dirac equation in the asymptotic regions of the two black hole geometries. We successfully obtain analytic phase shifts, with the help of which the scattering cross section is computed. The glory and spiral scattering phenomena are shown to be present, as in the case of massive fermion scattering by black holes.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant Nos.11875157,12147214the Doctoral Start-up Fund of Liaoning Normal University under Grant No.2024BSL018the Universitylevel National Research Project Cultivation Program under Grant No.2024170。
文摘The massless dark photon~γ can only interact with the Standard Model(SM)sector via higherdimensional operators.In this letter,we investigate its production associated with the ordinary photonγfrom the lepton flavor violation(LFV)process l_(i)→l_(j)γγ and di-production from the LFV process l_(i)→l_(j)γγ induced by dipole operators.Comparing the obtained numerical results with the corresponding experimental measurements,we obtain the constraints on the effective couplings of γ with the SM charged leptons.The upper limit of the effective coupling|DLμe|2+|DRμe|2coming from the process μ→e~γγis looser than the processμ→eγ by about one order of magnitude.
文摘A systematic rigorous analysis of both massless fermion fields in the mass spectra of superstring theory is carried out. Our interest is in dynamical aspects of these fields. An explicit novel expression for the propagator of the massless Rarita-Schwinger field (the gravitino), in the mass spectrum involving massless fermions in superstring theory in 10 dimensions, is derived. The analysis is carried in the presence of a non-constrained external source so that the full expression of the propagator emerges. The number of associated degrees of freedom is also obtained. We work in a Coulomb-like gauge. The massless Dirac field (the dilatino), the other massless fermion field in the mass spectra of superstring theory in 10 dimensions, is first investigated to this end.
文摘Applying perturbative QCD, we study the process Bc → Dsγ in the technicolor with a massless scalar doublet model (TCMLSM). There are mainly two mechanisms contributing to the Bc → D*sγ process. One proceeds through the short distance b → sγ transition and the other through weak annihilation accompanied by a photon emission.We find that, compared with the standard model, the modification of Bc → D*sγ from πρ (the physical pions in the TCMLSM) is so small that can be neglected for the allowed mass ofπρ. The weak-annihilation contribution is found to be about one order larger than that of the electromagnetic penguin diagrams.
基金supported Project supported by the National Natural Science Foundation of China (Grant No. 10873004)the Program for Excellent Talents at Hunan Normal University,China+4 种基金the National Basic Research Program of China (Grant No. 2010CB832803)the Key Program of the National Natural Science Foundation of China (Grant No. 10935013)the Construct Program of the National Key Disciplinethe Program for Changjiang Scholarsthe Innovative Research Team in University,China(Grant No. IRT0964)
文摘Recently, considerable progress has been made in understanding the early universe by loop quantum cosmology. Modesto et al. investigated the loop quantum black hole （LQBH）using improved semiclassical analysis and they found that the LQBH has two horizons, an event horizon and a Cauchy horizon, just like the Reissner-NordstrSm black hole. This paper focuses on the dynamical evolution of a massless scalar wave in the LQBH background. By investigating the relation between the complex frequencies of the massless scalar field and the LQBH parameters using the numerical method, we find that the polymeric parameter P makes the massless scalar field decay more quickly and makes the ground scalar wave oscillate slowly. However, the polymeric parameter P causes the frequency of the high harmonic massless scalar wave to shift according to its value. We also find that the loop quantum gravity area gap parameter a0 causes the massless scalar field to decay more slowly and makes the period of the massless scalar field wave become longer. In the complex ω plane, the frequency curves move counterclockwise when the polymeric parameter P increases and this spiral effect is more obvious for a higher harmonic scalar wave.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10873004)the State Key Development Program for Basic Research of China (Grant No. 2010CB832803)the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT0964)
文摘By using the partial wave method, we investigate the absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence. We obtained the expression of absorption cross sectionσabs（ω）=π/ω^2 ∑ t=0^∞ （2l＋1）｜Tωl（ω）｜^2=π/ω^2∑ t=0^∞（2l＋1）Гωl（ω）.Then we numerically carry out the absorption cross section and we find that the larger the angular momentum quantum number 1 is, the smaller the corresponding maximum value of the partial absorption cross section is, and that the total absorption cross section tends to the geometric-optical limit σhfabs≈ bc^2. We also find that higher value of ωq （state abs parameter of quintessence） corresponds to the higher value of absorption cross section gabs.
基金supported partly by the National Natural Science Foundation of China (Grant No. 12065012)Yunnan High-level Talent Training Support Plan Young & Elite Talents Project (Grant No. YNWR-QNBJ-2018-360)the Fund for Reserve Talents of Young and Middle-aged Academic and Technical Leaders of Yunnan Province (Grant No. 2018HB006)。
文摘We study the massless scalar quasinormal frequencies of an asymptotically flat static and spherically symmetric black hole with a nonzero magnetic charge in four-dimensional extended scalar-tensor-Gauss-Bonnet theory. The results show that the real part of the quasinormal frequency becomes larger and the imaginary part becomes smaller with increasing the magnetic charge or the angular harmonic index. The existence of magnetic charges will reduce the damping of scalar perturbation, but increase the frequency. We also study the absorption crosssection of the scalar field in this black hole. We find that its curve will become lower as the magnetic charge increases, i.e. the magnetic charge will weaken the absorption capacity of the black hole. Meanwhile, the high-frequency limit of the total absorption cross-section is just the area of black hole shadow.
基金the National Natural Science Foundation of China(Grant No.11565009)。
文摘The Dirac–Weyl equation characterized quasi-particles in the T3 lattice are studied under external magnetic field using the generalized uncertainty principle(GUP). The energy spectrum of the quasi-particles is found by the Nikiforov–Uvarov method. Based on the energy spectrum obtained, the thermodynamic properties are given, and the influence of the GUP on the statistical properties of systems is discussed. The results show that the energy and thermodynamic functions of massless Dirac–Weyl fermions in the T3 lattice depend on the variation of the GUP parameter.
文摘This article considers a static and spherical black hole(BH)in f(Q)gravity.f(Q)gravity is the extension of symmetric teleparallel general relativity,where both curvature and torsion are vanishing and gravity is described by nonmetricity.In this study,we investigate the possible implications of quasinormal mode(QNM)modified Hawking spectra and deflection angles generated by the model.The Wentzel–Kramers–Brillouin method is used to solve the equations of motion for massless Dirac perturbation fields and explore the impact of the nonmetricity parameter(Q_(0)).Based on the QNM computation,we can ensure that the BH is stable against massless Dirac perturbations and as Q_(0)increases the oscillatory frequency of the mode decreases.We then discuss the weak deflection angle in the weak field limit approximation.We compute the deflection angle up to the fourth order of approximation and show how the nonmetricity parameter affects it.We find that the Q_(0)parameter reduces the deflection angle.
基金Supported by the Natural Science Foundation of Education Department of Shannxi Province under Grant No 15JK1077the Doctorial Scientific Research Starting Fund of Shannxi University of Science and Technology under Grant No BJ12-02
文摘In our previous work [Chin. Phys. Lett. 35（2018） 010410], the quasinormal modes of massless scalar field perturbation in a noncommutative-geometry-inspired Schwarzschild black hole spacetime are studied using the third-order Wentzel–Kramers–Brillouin approximative approach. In this study, we extend the work to the cases of gravitational, electromagnetic and massless Dirac perturbations. The result further confirms that the noncommutative parameter plays an important role for the quasinormal frequencies.
基金The project supported partly by National Natural Science Foundation of China under Grant Nos. 10373003, 10475013, and NBRPC under Grant No. 2003CB716302
文摘The Casimir effect has been studied for various quantum fields in both fiat and curved spacetimes. As a further step along this line, we provide an explicit derivation of Casimlr effect for massless spin-3/2 field with periodic boundary condition imposed in four-dimensional Minkowski spacetime. The corresponding results with Dirichlet and Neumann boundary conditions are also discussed.
文摘The Daya Bay Collaboration has discovered that approximately 6.0%of active neutrinos were missing from the nuclear reaction container.This finding has led to a reinterpretation of the three known types of neutrinos.In this paper,we present an analysis based on deductive reasoning,proposing that neutrinos are massless in the longitudinal direction(referred to as“longitudinal mass-less”).This insight contributes to the broader body of literature on the subject.Additionally,our work resolves the long-standing mystery of CP conservation in strong interactions.Using advanced physical mathematics,we derive a sig-nificant result:the transformation between the third type of neutrino and pho-tons or gravitons.We express the probability of this transformation in quan-tum mechanics using sinc functions which arise from interference effects,providing analytical solutions.Furthermore,considering the mass constraints imposed by the seesaw mechanism—referred to here as the“compete mecha-nism”(a generalized seesaw model)—we argue that the actual phase 4π of CP violation precisely answers the fundamental question at hand.
基金supported by the National Natural Science Foundation of China(Grant Nos.12475051,12375051,12122504,and 12421005)the Science and Technology Innovation Program of Hunan Province(Grant No.2024RC1050)+1 种基金the Natural Science Foundation of Hunan Province(Grant No.2023JJ30384)the innovative research group of Hunan Province(Grant No.2024JJ1006).
文摘Simulating the nature of quantum fields in diverse spacetime backgrounds offers valuable insights for the fundamental comprehension of quantum mechanics and general relativity.Here we introduce a novel method for mapping the massless Dirac equation in 1+1D curved spacetime to a controllable quantum simulation model,applicable to various observers'perspectives.We perform numerical simulations of Simpson spacetime and calculate tunneling rates in Painlevéand Schwarzschild coordinates,which align closely with theoretical predictions of Hawking radiation.Additionally,we show the transition of Simpson spacetime from a regular black hole to a wormhole as the parameter“a>r_(s)”.This method facilitates the study of spacetime from various coordinate perspectives(observers),providing deeper insights and understanding.
基金supported by the Islamic Azad University,Kermanshah Branch,Kermanshah,Iran
文摘Physicists have been interested in quantization of spinor and vector free fields in 4-dimensional de Sitter space-time, in ambient space notation. The Gupta-Bleuler formalism has been extensively applied to the quantization of gauge invariant theories. The field equation of the massless spin-3/2 fields is gauge invariant in de Sitter space. In this paper, we study the quantization of massless spin-3/2 gauge fields in de Sitter space-time by the Gupta-Bleuler formalism. This triplet carries an indecomposable representation of the de Sitter group.
基金Supported by a grant of the Ministry of National Education and Scientific Research,RDI Programme for Space Technology and Advanced Research-STAR,project number 181/20.07.2017
文摘We study the scattering of massless Dirac fermions by Schwarzschild and Reissner-Nordstrm black holes. This is done by applying partial wave analysis to the scattering modes obtained after solving the massless Dirac equation in the asymptotic regions of the two black hole geometries. We successfully obtain analytic phase shifts, with the help of which the scattering cross section is computed. The glory and spiral scattering phenomena are shown to be present, as in the case of massive fermion scattering by black holes.
