In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ...In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ),n>|μ,are calculated up to the tenth and fourth orders,respectively,in the QCD sum rules according to the background field theory.After constructing the light-cone harmonic oscillator model for the pion twist-2,3 D As,we obtain their behaviors by matching the calculatedξ-moments.Then,the D→πtransition form factors(TFFs)are calculated using an approach based on QCD light-cone sum rules.The vector form factor at the large recoil region is f_(+)^(D)→^(π)(0)=0.627_(-0.080)^(+0.120).Using the rapidly converging simplified series expansion of z(q^(2),t),we present the TFFs and corresponding angular coefficients in the whole squared momentum transfer physical region.Based on nonstandard neutrino interactions,the■^(0)→π^(+)e■_(e)decay can be related to the■^(0)→π^(+)e■_(e)decay indirectly.Thus,we first describe the semileptonic decay process■^(0)→π^(+)e■_(e),differential decay widths,and branching fraction with B(■^(0)→π^(+)e■_(e))=0.308_(-0.066)^(+0.155)×10^(2).The■^(0)→π^(+)e■_(e)differential/total predictions for forward-backward asymmetry,q^(2)-differential flat terms,and lepton polarization asymmetry are also reported.The prediction for the D^(+)→π^(+)v■branching fraction isB(D^(+)→π^(+)v■)=1.85_(-0.46)+^(0.93)×10^(-8).展开更多
An analytical model is used to predict the effects of surface recombination current on the gain and transit time of GalnP/GaAs heterojunction bipolar transistors（HBTs）.The present analysis shows that consideration o...An analytical model is used to predict the effects of surface recombination current on the gain and transit time of GalnP/GaAs heterojunction bipolar transistors（HBTs）.The present analysis shows that consideration of the recombination current gives current gain values that are comparable to those of the experimental results.The dependence of current gain on temperature,base doping and emitter area are also analyzed,and the variation in collector current with emitter-base voltage,temperature and doping is considered.展开更多
基金Supported in part by the National Natural Science Foundation of China(12265010,12265009)the Project of Guizhou Provincial Department of Science and Technology(ZK[2021]024,ZK[2023]142)。
文摘In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ),n>|μ,are calculated up to the tenth and fourth orders,respectively,in the QCD sum rules according to the background field theory.After constructing the light-cone harmonic oscillator model for the pion twist-2,3 D As,we obtain their behaviors by matching the calculatedξ-moments.Then,the D→πtransition form factors(TFFs)are calculated using an approach based on QCD light-cone sum rules.The vector form factor at the large recoil region is f_(+)^(D)→^(π)(0)=0.627_(-0.080)^(+0.120).Using the rapidly converging simplified series expansion of z(q^(2),t),we present the TFFs and corresponding angular coefficients in the whole squared momentum transfer physical region.Based on nonstandard neutrino interactions,the■^(0)→π^(+)e■_(e)decay can be related to the■^(0)→π^(+)e■_(e)decay indirectly.Thus,we first describe the semileptonic decay process■^(0)→π^(+)e■_(e),differential decay widths,and branching fraction with B(■^(0)→π^(+)e■_(e))=0.308_(-0.066)^(+0.155)×10^(2).The■^(0)→π^(+)e■_(e)differential/total predictions for forward-backward asymmetry,q^(2)-differential flat terms,and lepton polarization asymmetry are also reported.The prediction for the D^(+)→π^(+)v■branching fraction isB(D^(+)→π^(+)v■)=1.85_(-0.46)+^(0.93)×10^(-8).
文摘An analytical model is used to predict the effects of surface recombination current on the gain and transit time of GalnP/GaAs heterojunction bipolar transistors（HBTs）.The present analysis shows that consideration of the recombination current gives current gain values that are comparable to those of the experimental results.The dependence of current gain on temperature,base doping and emitter area are also analyzed,and the variation in collector current with emitter-base voltage,temperature and doping is considered.
