In this work, we analyse semi-leptonic and non-leptonic weak decays of the heavy baryons： Λ_b,Ξ_b,Ωb and Λ_c,Ξ_c,Ωc. For non-leptonic decay modes, we study only the factorizable channels induced by the external...In this work, we analyse semi-leptonic and non-leptonic weak decays of the heavy baryons： Λ_b,Ξ_b,Ωb and Λ_c,Ξ_c,Ωc. For non-leptonic decay modes, we study only the factorizable channels induced by the external Wemission. The two spectator quarks in the baryonic transitions are treated as a diquark and form factors are calculated in the light-front approach. Using the results for form factors, we also calculate some corresponding semi-leptonic and non-leptonic decay widths. We find that our results are comparable with the available experimental data and other theoretical predictions. Decay branching fractions for many channels are found to reach the level 10^（-3）~10^（-2）,which is promising for discovery in future measurements at BESIII, LHCb and Belle II. The SU（3） symmetry in semi-leptonic decays is examined and sources of symmetry breaking are discussed.展开更多
Recently we have studied the instant-form quantization (IFQ) and the light-front quantization (LFQ) of the conformally gauge-fixed Polyakov D1 brane action using the Hamiltonian and path integral formulations. The IFQ...Recently we have studied the instant-form quantization (IFQ) and the light-front quantization (LFQ) of the conformally gauge-fixed Polyakov D1 brane action using the Hamiltonian and path integral formulations. The IFQ is studied in the equal world-sheet time framework on the hyperplanes defined by the world-sheet time σ0=τ=constant and the LFQ in the equal light-cone world-sheet time framework, on the hyperplanes of the light-front defined by the light-cone world-sheet time σ+= (τ+σ) =constant. The light-front theory is seen to be a constrained system in the sense of Dirac in contrast to the instant-form theory. However, owing to the gauge anomalous nature of these theories, both of these theories are seen to lack the usual string gauge symmetries defined by the world-sheet reparametrization invariance (WSRI) and the Weyl invariance (WI). In the present work we show that these theories when considered in the presence of background gauge fields such as the NSNS 2-form gauge field Bαβ(σ,τ) or in the presence of U(1) gauge field Aα(σ,τ) and the constant scalar axion field C(σ,τ), then they are seen to possess the usual string gauge symmetries (WSRI and WI). In fact, these background gauge fields are seen to behave as the Wess-Zumino or Stueckelberg fields and the terms containing these fields are seen to behave as Wess-Zumino or Stueckelberg terms for these theories.展开更多
FCNC processes offer important tools to test the Standard Model（SM）and to search for possible new physics.In this work,we investigate the s→dvv rare hyperon decays in SM and beyond.We find that in SM the branching ...FCNC processes offer important tools to test the Standard Model（SM）and to search for possible new physics.In this work,we investigate the s→dvv rare hyperon decays in SM and beyond.We find that in SM the branching ratios for these rare hyperon decays range from 10-14 to 10-11.When all the errors in the form factors are included,we find that the final branching ratios for most decay modes have an uncertainty of about 5% to 10%.After taking into account the contribution from new physics,the generalized SUSY extension of SM and the minimal 331 model,the decay widths for these channels can be enhanced by a factor of 2～7.展开更多
The electromagnetic form factors and low-energy observables of the deuteron are studied with the help of the light-front approach, where the deuteron is regarded as a weakly bound state of a proton and a neutron. Both...The electromagnetic form factors and low-energy observables of the deuteron are studied with the help of the light-front approach, where the deuteron is regarded as a weakly bound state of a proton and a neutron. Both the S and D wave interacting vertexes among the deuteron, proton, and neutron are taken into account. Moreover,the regularization functions are also introduced. In our calculations, the vertex and the regularization functions are employed to simulate the momentum distribution inside the deuteron. Our numerical results show that the lightfront approach can roughly reproduce the deuteron electromagnetic form factors, like charge G0, magnetic G1, and quadrupole G2, in the low Q~2 region. The important effect of the D wave vertex on G2is also addressed.展开更多
基金Supported by National Natural Science Foundation of China(11575110,11655002,11735010)Natural Science Foundation of Shanghai(15DZ2272100)
文摘In this work, we analyse semi-leptonic and non-leptonic weak decays of the heavy baryons： Λ_b,Ξ_b,Ωb and Λ_c,Ξ_c,Ωc. For non-leptonic decay modes, we study only the factorizable channels induced by the external Wemission. The two spectator quarks in the baryonic transitions are treated as a diquark and form factors are calculated in the light-front approach. Using the results for form factors, we also calculate some corresponding semi-leptonic and non-leptonic decay widths. We find that our results are comparable with the available experimental data and other theoretical predictions. Decay branching fractions for many channels are found to reach the level 10^（-3）~10^（-2）,which is promising for discovery in future measurements at BESIII, LHCb and Belle II. The SU（3） symmetry in semi-leptonic decays is examined and sources of symmetry breaking are discussed.
文摘Recently we have studied the instant-form quantization (IFQ) and the light-front quantization (LFQ) of the conformally gauge-fixed Polyakov D1 brane action using the Hamiltonian and path integral formulations. The IFQ is studied in the equal world-sheet time framework on the hyperplanes defined by the world-sheet time σ0=τ=constant and the LFQ in the equal light-cone world-sheet time framework, on the hyperplanes of the light-front defined by the light-cone world-sheet time σ+= (τ+σ) =constant. The light-front theory is seen to be a constrained system in the sense of Dirac in contrast to the instant-form theory. However, owing to the gauge anomalous nature of these theories, both of these theories are seen to lack the usual string gauge symmetries defined by the world-sheet reparametrization invariance (WSRI) and the Weyl invariance (WI). In the present work we show that these theories when considered in the presence of background gauge fields such as the NSNS 2-form gauge field Bαβ(σ,τ) or in the presence of U(1) gauge field Aα(σ,τ) and the constant scalar axion field C(σ,τ), then they are seen to possess the usual string gauge symmetries (WSRI and WI). In fact, these background gauge fields are seen to behave as the Wess-Zumino or Stueckelberg fields and the terms containing these fields are seen to behave as Wess-Zumino or Stueckelberg terms for these theories.
基金Supported in part by National Natural Science Foundation of China(11575110,11735010,11911530088)Natural Science Foundation of Shanghai(15DZ2272100)and Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education
文摘FCNC processes offer important tools to test the Standard Model（SM）and to search for possible new physics.In this work,we investigate the s→dvv rare hyperon decays in SM and beyond.We find that in SM the branching ratios for these rare hyperon decays range from 10-14 to 10-11.When all the errors in the form factors are included,we find that the final branching ratios for most decay modes have an uncertainty of about 5% to 10%.After taking into account the contribution from new physics,the generalized SUSY extension of SM and the minimal 331 model,the decay widths for these channels can be enhanced by a factor of 2～7.
基金Supported by National Natural Science Foundation of China(10975146,11475192)The fund provided by the Sino-German CRC110 “Symmetries and the Emergence of Structure in QCD”FAPESP grant 2011/11973-4 for funding his visit to ICTP-SAIFR
文摘The electromagnetic form factors and low-energy observables of the deuteron are studied with the help of the light-front approach, where the deuteron is regarded as a weakly bound state of a proton and a neutron. Both the S and D wave interacting vertexes among the deuteron, proton, and neutron are taken into account. Moreover,the regularization functions are also introduced. In our calculations, the vertex and the regularization functions are employed to simulate the momentum distribution inside the deuteron. Our numerical results show that the lightfront approach can roughly reproduce the deuteron electromagnetic form factors, like charge G0, magnetic G1, and quadrupole G2, in the low Q~2 region. The important effect of the D wave vertex on G2is also addressed.
