We calculate theD^0-D^-0 mixing parameter y in the factorization-assisted topological-amplitude（FAT）approach, considering contributions from D^0→PP, PV, and VV modes, where P（V） stands for a pseudoscalar（vector...We calculate theD^0-D^-0 mixing parameter y in the factorization-assisted topological-amplitude（FAT）approach, considering contributions from D^0→PP, PV, and VV modes, where P（V） stands for a pseudoscalar（vector） meson. The D^0→PP and PV decay amplitudes are extracted in the FAT approach, and the D^0→VV decay amplitudes with final states in the longitudinal polarization are estimated via the parameter set for D^0→PV. It is found that the VV contribution to y, being of order of 10-4, is negligible, and that the PP and PV contributions amount only up to y_（PP＋PV） =（0.21±0.07）%, a prediction more precise than those previously obtained in the literature,and much lower than the experimental data yexp =（0.61 ±0.08）%. We conclude that D^0 meson decays into other two-body and multi-particle final states are relevant to the evaluation of y, so it is difficult to understand it fully in an exclusive approach.展开更多
We explain the framework for calculating next-to-leading-order （NLO） corrections to exclusive processes in the kT factorization theorem, taking πγ^＊→γ as an example. Patrons off-shell by kT^2 are considered in ...We explain the framework for calculating next-to-leading-order （NLO） corrections to exclusive processes in the kT factorization theorem, taking πγ^＊→γ as an example. Patrons off-shell by kT^2 are considered in both the quark diagrams from full QCD and the effective diagrams for the pion wave function. The gauge dependences in the above two sets of diagrams cancel, when deriving the kw-dependent hard kernel as their difference. The light-cone singularities in the kT-dependent pion wave function are regularized by rotating the Wilson lines away from the light cone. Both the large double logarithms In^2 kT and In^2x, x being a parton momentum fraction, arise from the loop correction to the virtual photon vertex, the former being absorbed into the pion wave function, and the latter into a jet function.展开更多
基金Supported by National Natural Science Foundation of China(11347027,11505083,11375208,11521505,1162113100,11235005,U1732101)Ministry of Science and Technology of R.O.C.(MOST-104-2112-M-001-037-MY3)DFG Forschergruppe FOR 1873"Quark Flavour Physics and Effective Field Theories"
文摘We calculate theD^0-D^-0 mixing parameter y in the factorization-assisted topological-amplitude（FAT）approach, considering contributions from D^0→PP, PV, and VV modes, where P（V） stands for a pseudoscalar（vector） meson. The D^0→PP and PV decay amplitudes are extracted in the FAT approach, and the D^0→VV decay amplitudes with final states in the longitudinal polarization are estimated via the parameter set for D^0→PV. It is found that the VV contribution to y, being of order of 10-4, is negligible, and that the PP and PV contributions amount only up to y_（PP＋PV） =（0.21±0.07）%, a prediction more precise than those previously obtained in the literature,and much lower than the experimental data yexp =（0.61 ±0.08）%. We conclude that D^0 meson decays into other two-body and multi-particle final states are relevant to the evaluation of y, so it is difficult to understand it fully in an exclusive approach.
基金Supported by National Science Council (NSC-95-2112-M-050-MY3)
文摘We explain the framework for calculating next-to-leading-order （NLO） corrections to exclusive processes in the kT factorization theorem, taking πγ^＊→γ as an example. Patrons off-shell by kT^2 are considered in both the quark diagrams from full QCD and the effective diagrams for the pion wave function. The gauge dependences in the above two sets of diagrams cancel, when deriving the kw-dependent hard kernel as their difference. The light-cone singularities in the kT-dependent pion wave function are regularized by rotating the Wilson lines away from the light cone. Both the large double logarithms In^2 kT and In^2x, x being a parton momentum fraction, arise from the loop correction to the virtual photon vertex, the former being absorbed into the pion wave function, and the latter into a jet function.
