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Mass spectra of heavy pseudoscalars using instantaneous Bethe-Salpeter equation with different kernels

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arXiv 2020年

作者： Li, Wei Wang, Ying-Long Feng, Tai-Fu Wang, Guo-Li Department of Physics Hebei University Baoding071002 China Key Laboratory of High-Precision Computation and Application of Quantum Field Theory of Hebei Province Baoding China

We solved the instantaneous Bethe-Salpeter equation for heavy pseudoscalars in different kernels, where the kernels are obtained using linear scalar potential plus one gluon exchange vector potentials in Feynman gauge, Landau gauge, Coulomb gauge and time-component Coulomb gauge. We obtained the mass spectra of heavy pseudoscalars, and compared the results between different kernels, found that using the same parameters we obtain the smallest mass splitting in time-component Coulomb gauge, the similar largest mass splitting in Feynman and Coulomb gauges, middle size splitting in Landau gauge. Copyright © 2020, The Authors. All rights reserved.

关键词： Gages

The mass spectrum and wave functions of the Bc system

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arXiv 2022年

作者： Wang, Guo-Li Wang, Tianghong Li, Qiang Chang, Chao-Hsi Department of Physics Hebei University Baoding071002 China Key Laboratory of High-Precision Computation Application of Quantum Field Theory of Hebei Province Baoding China School of Physics Harbin Institute of Technology Harbin150001 China School of Physical Science and Technology Northwestern Polytechnical University Xi'An710072 China Institute of Theoretical Physics Chinese Academy of Science Beijing100190 China P.O. Box 8730 Beijing100190 China

The spectrum and relativistic wave functions of Bc system are investigated via solving the complete Salpeter equation. Emphases are put on the study of the partial waves of each JP state. Our study shows that there are three categories of JP states. The first category contains 0− and 0+ states, which are 1S0 dominant state with a small amount of P wave and 3P0 dominant state with a small amount of S wave, respectively. The second category includes the natural parity states, such as 1−, 2+, 3−, etc. Taking the 1− state as an example, we study it in two cases. One is the 3S1 dominant state with a small amount of P and D waves, and the other is the 3D1 dominant state but contains a large amount of S and P wave components. The third category includes the unnatural parity states, such as 1+, 2−, 3+, etc. For the 1+ spectrum, the states are grouped into pairs with different radial quantum numbers. Each pair contains two 1P1 − 3P1 mixing states, and the corresponding mixing angles are calculated by using the relativistic wave functions. Copyright © 2022, The Authors. All rights reserved.

关键词： Wave functions

The newly observed state Ds0(2590)+

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arXiv 2021年

作者： Wang, Guo-Li Li, Wei Feng, Tai-Fu Wang, Ying-Long Liu, Yu-Bin Department of Physics Hebei University Baoding071002 China Key Laboratory of High-Precision Computation Application of Quantum Field Theory of Hebei Province Baoding China Department of Primary Education Baoding Preschool Teachers College Baoding072750 China School of Physics Nankai University Tianjin 300071 China

We choose the Reduction Formula, PCAC and Low Energy theory to reduce the S matrix of a OZI allowed two-body strong decay involving a light pseudoscalar, the covariant transition amplitude formula with relativistic wave functions as input is derived. After confirm this method by the decay D∗(2010) → Dπ, we study the newly observed Ds0(2590)+ with supposing it to be the state Ds(21S0)+, we find its decay width Γ is highly sensitive to the Ds0(2590)+ mass, which result in the meaningless comparison of widths by different models with various input masses. Instead of width, we studied the overlap integral over the wave functions of initial and final states, here we parameterized it as X which is model-independent, and the ratio (Equation presented), both are almost mass independent, to give us useful information. The results show that, all the existing theoretical predictions (Equation presented) and (Equation presented) MeV−2 are smaller than experimental data (Equation prsented) and (Equation prsented) MeV−2. Further compared with (Equation presented), the current data (Equation presented) is too big to be an reasonable value, so it is early to say Ds0(2590)+ is the conventional Ds(21S0)+ meson. Copyright © 2021, The Authors. All rights reserved.

关键词： Wave functions

Feynman integrals of Grassmannians

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Physical Review D 2022年第11期106卷 116025-116025页

作者： Tai-Fu Feng Hai-Bin Zhang Chao-Hsi Chang Department of Physics Hebei University Baoding 071002 China Hebei Key Laboratory of High-precision Computation and Application of Quantum Field Theory Baoding 071002 China Research Center for Computational Physics of Hebei Province Baoding 071002 China Department of Physics Guangxi University Nanning 530004 China Department of Physics Chongqing University Chongqing 401331 China Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Science Beijing 100190 China CCAST (World Laboratory) P.O. Box 8730 Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China

We embed Feynman integrals in the subvarieties of Grassmannians through homogenization of the integrands in projective space, then obtain Gel’fand-Kapranov-Zelevinsky systems satisfied by those scalar integrals. The Feynman integral can be written as linear combinations of the hypergeometric functions of a fundamental solution system in neighborhoods of regular singularities of the Gel’fand-Kapranov-Zelevinsky system, whose linear combination coefficients are determined by the integral on an ordinary point or some regular singularities. Taking some Feynman diagrams as examples, we elucidate in detail how to obtain the fundamental solution systems of Feynman integrals in neighborhoods of regular singularities. Furthermore we also present the parametric representations of Feynman integrals of the two-loop self-energy diagrams that are convenient to embed in the subvarieties of Grassmannians.

关键词： Feynman diagrams

The order analysis for the two loop corrections to lepton MDM

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arXiv 2020年

作者： Zhao, Shu-Min Dong, Xing-Xing Su, Lu-Hao Zhang, Hai-Bin Department of Physics Hebei University Baoding071002 China Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province Baoding071002 China

The experimental data of the magnetic dipole moment(MDM) of lepton(e, µ) is very exact. The deviation between the experimental data and the standard model prediction maybe comes from new physics contribution. In the supersymmetric models, there are very many two loop diagrams contributing to the lepton MDM. In supersymmetric models, we suppose two mass scales MSH and M with MSH M for supersymmetric particles. Squarks belong to MSH and the other supersymmetric particles belong to M. We analyze the order of the contributions from the two loop diagrams. The two loop triangle diagrams corresponding to the two loop self-energy diagram satisfy Ward identity, and their contributions possess particular factors. This work can help to distinguish the important two loop diagrams giving corrections to lepton MDM. Copyright © 2020, The Authors. All rights reserved.

关键词： Supersymmetry

Logarithmic correction to black hole entropy from the nonlocality of quantum gravity

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arXiv 2021年

作者： Xiao, Yong Tian, Yu Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province College of Physical Science and Technology Hebei University Baoding071002 China School of Physics University of Chinese Academy of Sciences Beijing100049 China Institute of Theoretical Physics Chinese Academy of Sciences Beijing100190 China

It has been known for many years that the leading correction to the black hole entropy is a logarithmic term, which is universal and closely related to conformal anomaly. A fully consistent analysis of this issue has to take quantum backreactions to the black hole geometry into account. However, it was always unclear how to naturally derive the modified black hole metric especially from an effective action, because the problem refers to the elusive non-locality of quantum gravity. In this paper, we show that this problem can be resolved within an effective field theory (EFT) framework of quantum gravity. Our work suggests that the EFT approach provides a powerful and self-consistent tool for studying the quantum gravitational corrections to black hole geometries and thermodynamics. Copyright © 2021, The Authors. All rights reserved.

关键词： Gravitation

Λc(2910) and Λc(2940) as conventional baryons dressed with the D*N channel

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Physical Review D 2023年第3期107卷 034036-034036页

作者： Zi-Le Zhang Zhan-Wei Liu Si-Qiang Luo Fu-Lai Wang Bo Wang Hao Xu School of Physical Science and Technology Lanzhou University Lanzhou 730000 China Research Center for Hadron and CSR Physics Lanzhou University and Institute of Modern Physics of CAS Lanzhou 730000 China Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Province and Frontiers Science Center for Rare Isotopes Lanzhou University Lanzhou 730000 China School of Physical Science and Technology Hebei University Baoding 071002 China Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province Baoding 071002 China Research Center for Computational Physics of Hebei Province Baoding 071002 China Institute of Theoretical Physics College of Physics and Electronic Engineering Northwest Normal University Lanzhou 730070 China Lanzhou Center for Theoretical Physics Lanzhou University Lanzhou 730000 China

In this work, we treat Λc(2910)+ and Λc(2940)+ as the conventional udc cores dressed with the D*N channel. We provide a possible interpretation to both Λc(2910)+ and Λc(2940)+ within the same framework. In the study, we consider not only the effects between the conventional triquark core and the D*N channel but also the D*N−D*N interactions. The mass of the Λc state with JP=1/2− is larger than that with JP=3/2− in this unquenched picture, which is very different from the prediction of the conventional quenched quark model. Based on the mass spectrum, the spin parity of Λc(2940)+ is more likely to be 1/2−, while Λc(2910)+ prefers 3/2−. We look forward to the future experiments that can test our results with more precise experimental data.

关键词： Quark model Baryons Mass

Feynman Integrals of Grassmannians

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arXiv 2022年

作者： Feng, Tai-Fu Zhang, Hai-Bin Chang, Chao-Hsi Department of Physics Hebei University Baoding071002 China Hebei Key Laboratory of High-precision Computation and Application of Quantum Field Theory Baoding071002 China Department of Physics Guangxi University Nanning530004 China Department of Physics Chongqing University Chongqing401331 China Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Science Beijing100190 China P.O.Box 8730 Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100049 China

We embed Feynman integrals in the subvarieties of Grassmannians through homogenization of the integrands in projective space, then obtain GKZ-systems satisfied by those scalar integrals. The Feynman integral can be written as linear combinations of the hypergeometric functions of a fundamental solution system in neighborhoods of regular singularities of the GKZ-system, whose linear combination coefficients are determined by the integral on an ordinary point or some regular singularities. Taking some Feynman diagrams as examples, we elucidate in detail how to obtain the fundamental solution systems of Feynman integrals in neighborhoods of regular singularities. Furthermore we also present the parametric representations of Feynman integrals of the 2-loop self-energy diagrams which are convenient to embed in the subvarieties of Grassmannians. © 2022, CC0.

关键词：

Average speed and its powers vn of a heavy quark in quarkonia

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Physical Review D 2020年第11期101卷 116011-116011页

作者： Guo-Li Wang Tai-Fu Feng Xing-Gang Wu Department of Physics Hebei University Baoding 071002 China Hebei Key Laboratory of High-precision Computation and Application of Quantum Field Theory Baoding 071002 China Department of Physics Chongqing University Chongqing 401331 China

The typical velocity of a heavy quark in a quarkonium is a widely used quantity, in this paper, based on the relativistic Bethe-Salpeter equation method, we calculate the average values |q|n¯ and |v|n¯≡vn of a heavy quark in a S wave or P wave quarkonium rest frame, where q and v are the three dimensional momentum and velocity, n=1, 2, 3, 4. For a charm quark in J/ψ, we obtained vJ/ψ=0.46, vJ/ψ2=0.26, vJ/ψ3=0.18, and vJ/ψ4=0.14, for a bottom quark in ϒ(1S), vϒ(1S)=0.24, vϒ(1S)2=0.072, vϒ(1S)3=0.025, and vϒ(1S)4=0.010. The values indicate that vn>vn1·vn2, where n1+n2=n, which is correct for all the charmonia and bottomonia. Our results also show the poor convergence if we make the speed expansion in charmonium system, but good for bottomonium. Based on the vn values and the following obtained relations v4Sn>v3Sn>v2Sn>v1Sn, v4Pn>v3Pn>v2Pn>v1Pn, and vmPn>vmSn (n, m=1, 2, 3, 4), we conclude that highly excited quarkonia have larger relativistic corrections than those of the corresponding low excited and ground states, and there are large relativistic corrections in charmonium system.

关键词： Bethe-Salpeter equation Bound states