Motivated by our previous study[Phys.Rev.D 104(1),016021(2021)]on the pionic leading-twist distribution amplitude(DA),we revisit theρ-me son leading-twist longitudinal DAφ_(2;ρ)^(‖)(x,μ)in this study.A model prop...Motivated by our previous study[Phys.Rev.D 104(1),016021(2021)]on the pionic leading-twist distribution amplitude(DA),we revisit theρ-me son leading-twist longitudinal DAφ_(2;ρ)^(‖)(x,μ)in this study.A model proposed by Chang based on the DYyson-Schwinger equations is adopted to describe the behavior ofφ_(2;ρ)^(‖)(x,μ).However,theξ-moments ofφ_(2;ρ)^(‖)(x,μ)are calculated with the QCD sum rules in the framework of the background field theory.The sum rule formulas for these moments are improved.More accurate values for the first five nonzeroξ-moments at the typical scaleμ=(1.0,1.4,2.0,3.0)GeV are given,e.g.,atμ=1 GeV,(ξ^(2))>_(2;ρ)^(‖)=0.220(6),(ξ^(4))>_(2;ρ)^(‖)=0.103(4),(ξ^(6))>_(2;ρ)^(‖)=0.066(5),(ξ^(8))>_(2;ρ)^(‖)=0.046(4),and(ξ^(10))>_(2;ρ)^(‖)=0.035(3).By fitting these values with the least squares method,the DSE model forφ_(2;ρ)(x,μ)is determined.By taking the left-handed current light-cone sum rule approach,we obtain the transition form factor in the large recoil region,i.e.,A_(1)(0)=0.498_(-0.012)^(+0.014),A_(2)(0)=0.460_(-0.047)^(+0.055),and V(0)=0.800_(-0.014)^(+0.015),and the ratio r_(2)=0.923_(-0.119)^(+0.133),rV=1.607_(-0.071)^(+0.071).After extrapolating with a rapidly converging series based on z(t)-expansion,we present the|V_(cd)|-independent decay width for the semileptonic decays D→ρ^(l+)v_(l).Finally,the branching fractions are B(D^(0)→ρ^(-)e+v_(e))=1.825_(-0.162)^(+0.170)±0.004,B(D^(+)→ρ^(0)e+v_(e))=2.299_(-0.204)^(+0.214)±0.011,B(D^(0)→ρ^(-)μ^(+)v_(μ))=1.816_(-0.160)^(+0.168)±0.004,and B(D^(+)→ρ^(0)μ+v_(μ))=2.288_(-0.201)^(+0.212)±0.011.展开更多
Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this...Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this decay may be evidence of new physics beyond the SM.Usually,the D-meson twist-2,3 distribution amplitudes(DAs)Φ2;D(x,μ),d3:D(x,μ),and$g:D(x,μ)are the main error sources when perturbative QCD factorization and light-cone QCD sum rules are used to study B→Dtve.Therefore,it is important to obtain more reasonable and accurate behaviors for these DAs.Motivated by our previous work[Phys.Rev.D 104,no.1,016021(2021)]on pionic leading-twist DA,we revisit D-meson twist-2,3 DAsΦ2:D(x,μ),Φp3:D(x,μ),andΦσ3:D(x,μ).New sum rule formulae for the-moments of these three DAs are suggested for obtaining more accurate values.The light-cone harmonic oscillator models for the DAs are improved,and their parameters are determined by fitting the values of-moments via the least squares method.展开更多
To date,the behavior of the pionic leading-twist distribution amplitude(DA)φ2;π(x,μ)-which is a universal physical quantity and is introduced into high-energy processes involving pions based on the factorization th...To date,the behavior of the pionic leading-twist distribution amplitude(DA)φ2;π(x,μ)-which is a universal physical quantity and is introduced into high-energy processes involving pions based on the factorization theorem-is not completely consistent.The form ofφ2;π(x,μ)is usually described by phenomenological models and constrained by the experimental data on exclusive processes containing pions or the moments computed using QCD sum rules and the lattice QCD theory.Evidently,an appropriate model is extremely important to determine the exact behavior ofφ2;π(x,μ).In this paper,by adopting the least squares method to fit theξ-moments calculated using QCD sum rules based on the background field theory,we perform an analysis on several commonly used models of the pionic leading-twist DA in the literature;these include the truncation form of the Gegenbauer polynomial series,the light-cone harmonic oscillator model,the form extracted from the Dyson-Schwinger equations,the model from the light-front holographic AdS/QCD,and a simple power-law parametrization form.展开更多
It is noted that in the new Particle Data Group(PDG) version the rare decays of the Λ_(b) baryon have been revised with more accuracy. The new results show that most of the existing theoretical results on the process...It is noted that in the new Particle Data Group(PDG) version the rare decays of the Λ_(b) baryon have been revised with more accuracy. The new results show that most of the existing theoretical results on the process Λ_(b)→Λ_(γ) Lgbare larger than those of experiments. With the improved higher-order light-cone distribution amplitudes of the Λ baryon, we reanalyze the process in the framework of light-cone quantum chromodynamics sum rules and the branching ratio is estimated to be Br (Λ_(b)→Λ_(γ))=(7.38-0.39+0.40)×10^(16), which is consistent with the new experimental result. Furthermore, another process Λ_(b)→Λl+l- is also analyzed in the same frame. The final branching ratio is calculated to be Br (Λ_(b)→Λl+l-)=1.20×10^(-6), which is in good accordance with the data from the PDG and other theoretical predictions.展开更多
基金Supported in part by the National Natural Science Foundation of China(12265009,12265010,12147102)the Project of Guizhou Provincial Department of Science and Technology(ZK[2021]024,ZK[2023]142)+1 种基金the Project of Guizhou Provincial Department of Education(KY[2021]030)the Chongqing Graduate Research and Innovation Foundation(ydstd1912)。
文摘Motivated by our previous study[Phys.Rev.D 104(1),016021(2021)]on the pionic leading-twist distribution amplitude(DA),we revisit theρ-me son leading-twist longitudinal DAφ_(2;ρ)^(‖)(x,μ)in this study.A model proposed by Chang based on the DYyson-Schwinger equations is adopted to describe the behavior ofφ_(2;ρ)^(‖)(x,μ).However,theξ-moments ofφ_(2;ρ)^(‖)(x,μ)are calculated with the QCD sum rules in the framework of the background field theory.The sum rule formulas for these moments are improved.More accurate values for the first five nonzeroξ-moments at the typical scaleμ=(1.0,1.4,2.0,3.0)GeV are given,e.g.,atμ=1 GeV,(ξ^(2))>_(2;ρ)^(‖)=0.220(6),(ξ^(4))>_(2;ρ)^(‖)=0.103(4),(ξ^(6))>_(2;ρ)^(‖)=0.066(5),(ξ^(8))>_(2;ρ)^(‖)=0.046(4),and(ξ^(10))>_(2;ρ)^(‖)=0.035(3).By fitting these values with the least squares method,the DSE model forφ_(2;ρ)(x,μ)is determined.By taking the left-handed current light-cone sum rule approach,we obtain the transition form factor in the large recoil region,i.e.,A_(1)(0)=0.498_(-0.012)^(+0.014),A_(2)(0)=0.460_(-0.047)^(+0.055),and V(0)=0.800_(-0.014)^(+0.015),and the ratio r_(2)=0.923_(-0.119)^(+0.133),rV=1.607_(-0.071)^(+0.071).After extrapolating with a rapidly converging series based on z(t)-expansion,we present the|V_(cd)|-independent decay width for the semileptonic decays D→ρ^(l+)v_(l).Finally,the branching fractions are B(D^(0)→ρ^(-)e+v_(e))=1.825_(-0.162)^(+0.170)±0.004,B(D^(+)→ρ^(0)e+v_(e))=2.299_(-0.204)^(+0.214)±0.011,B(D^(0)→ρ^(-)μ^(+)v_(μ))=1.816_(-0.160)^(+0.168)±0.004,and B(D^(+)→ρ^(0)μ+v_(μ))=2.288_(-0.201)^(+0.212)±0.011.
基金Supported in part by the National Natural Science Foundation of China(12265009,12265010)the Project of Guizhou Provincial Department of Science and Technology(ZK[2021]024,ZK[2023]142)+1 种基金the Project of Guizhou Provincial Department of Education(KY[2021]030)the Chongqing Graduate Research and Innovation Foundation(ydstd1912)。
文摘Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this decay may be evidence of new physics beyond the SM.Usually,the D-meson twist-2,3 distribution amplitudes(DAs)Φ2;D(x,μ),d3:D(x,μ),and$g:D(x,μ)are the main error sources when perturbative QCD factorization and light-cone QCD sum rules are used to study B→Dtve.Therefore,it is important to obtain more reasonable and accurate behaviors for these DAs.Motivated by our previous work[Phys.Rev.D 104,no.1,016021(2021)]on pionic leading-twist DA,we revisit D-meson twist-2,3 DAsΦ2:D(x,μ),Φp3:D(x,μ),andΦσ3:D(x,μ).New sum rule formulae for the-moments of these three DAs are suggested for obtaining more accurate values.The light-cone harmonic oscillator models for the DAs are improved,and their parameters are determined by fitting the values of-moments via the least squares method.
基金Supported in part by the National Natural Science Foundation of China(12265009,12265010,12175025,12147102)the Project of Guizhou Provincial Department of Science and Technology(ZK[2021]024)+1 种基金the Project of Guizhou Provincial Department of Education(KY[2021]030)the Chongqing Graduate Research and Innovation Foundation(ydstd1912)。
文摘To date,the behavior of the pionic leading-twist distribution amplitude(DA)φ2;π(x,μ)-which is a universal physical quantity and is introduced into high-energy processes involving pions based on the factorization theorem-is not completely consistent.The form ofφ2;π(x,μ)is usually described by phenomenological models and constrained by the experimental data on exclusive processes containing pions or the moments computed using QCD sum rules and the lattice QCD theory.Evidently,an appropriate model is extremely important to determine the exact behavior ofφ2;π(x,μ).In this paper,by adopting the least squares method to fit theξ-moments calculated using QCD sum rules based on the background field theory,we perform an analysis on several commonly used models of the pionic leading-twist DA in the literature;these include the truncation form of the Gegenbauer polynomial series,the light-cone harmonic oscillator model,the form extracted from the Dyson-Schwinger equations,the model from the light-front holographic AdS/QCD,and a simple power-law parametrization form.
文摘It is noted that in the new Particle Data Group(PDG) version the rare decays of the Λ_(b) baryon have been revised with more accuracy. The new results show that most of the existing theoretical results on the process Λ_(b)→Λ_(γ) Lgbare larger than those of experiments. With the improved higher-order light-cone distribution amplitudes of the Λ baryon, we reanalyze the process in the framework of light-cone quantum chromodynamics sum rules and the branching ratio is estimated to be Br (Λ_(b)→Λ_(γ))=(7.38-0.39+0.40)×10^(16), which is consistent with the new experimental result. Furthermore, another process Λ_(b)→Λl+l- is also analyzed in the same frame. The final branching ratio is calculated to be Br (Λ_(b)→Λl+l-)=1.20×10^(-6), which is in good accordance with the data from the PDG and other theoretical predictions.
