In this paper,the proton structure function F_(2)^(p)(x,Q^(2))at small-x is investigated using an analytical solution to the Balitsky–Kovchegov(BK)equation.In the context of the color dipole description of deep inela...In this paper,the proton structure function F_(2)^(p)(x,Q^(2))at small-x is investigated using an analytical solution to the Balitsky–Kovchegov(BK)equation.In the context of the color dipole description of deep inelastic scattering(DIS),the structure function F_(2)^(p)(x,Q^(2))is computed by applying the analytical expression for the scattering amplitude N(k,Y)derived from the BK solution.At transverse momentum k and total rapidity Y,the scattering amplitude N(k,Y)represents the propagation of the quark-antiquark dipole in the color dipole description of DIS.Using the BK solution we extracted the integrated gluon density xg(x,Q^(2))and then compared our theoretical estimation with the LHAPDF global data fits,NNPDF3.1sx and CT18.Finally,we have investigated the behavior of F_(2)^(p)(x,Q^(2))in the kinematic region of 10^(-5)≤x≤10^(-2)and 2.5 GeV^(2)≤Q^(2)≤60 GeV^(2).Our predicted results for F_(2)^(p)(x,Q^(2))within the specified kinematic region are in good agreement with the recent high-precision data for F_(2)^(p)(x,Q^(2))from HERA(H1 Collaboration)and the LHAPDF global parametrization group NNPDF3.1sx.展开更多
By employing the perturbative QCD （pQCD） factorization approach, we calculate some important next- to-leading-order （NLO） contributions to the two-body charmless hadronic decays B^＋ →ρ^＋η（＇） and B^0 → ρ^...By employing the perturbative QCD （pQCD） factorization approach, we calculate some important next- to-leading-order （NLO） contributions to the two-body charmless hadronic decays B^＋ →ρ^＋η（＇） and B^0 → ρ^0（ω, φ）η（＇）, induced by the vertex QCD corrections, the quark-loops as well as the chromo-magnetic penguins. From the numerical results and phenomenological analysis we find that （a） for B^± → ρ^±η（＇） （B^0 → ρ^0（ω, φ）η（＇）decays, the partial NLO contributions to branching ratios are small （large） in magnitude; and （b） the pQCD predictions for ACP^dir（B^± → ρ^±η（＇）） are consistent with the data, while the predicted .ACP（B^0 → ρ^0（ω）η（＇）） are generally large in magnitude and could be tested by the forthcoming LHCb experiments.展开更多
The rare decays Bs^0（B^-0 s）→D^±π^-＋ can occur only via annihilation-type diagrams in the standard model. In this paper, we calculate branching ratios of these decays in perturbative QCD approach ignoring so...The rare decays Bs^0（B^-0 s）→D^±π^-＋ can occur only via annihilation-type diagrams in the standard model. In this paper, we calculate branching ratios of these decays in perturbative QCD approach ignoring soft final state interaction. From our calculation, we find that their branching ratios are at O（10^-6） with large CP asymmetry, which may be measured in LHC-b experiment in the future.展开更多
In this paper,we calculate the branching ratios for B^+→D_s^+η,B^+→D_s^+η′,B^+→D_s^(*+)η and B^+→D_s^(*+)η′decays by employing the perturbative QCD (pQCD) factorization approach.Under the two kinds of η-η...In this paper,we calculate the branching ratios for B^+→D_s^+η,B^+→D_s^+η′,B^+→D_s^(*+)η and B^+→D_s^(*+)η′decays by employing the perturbative QCD (pQCD) factorization approach.Under the two kinds of η-η′ mixingschemes,the quark-flavor mixing scheme and the singlet-octet mixing scheme,we find that the calculated branchingratios agree well with the currently available experimental upper limits.We also consider the so called 'f_D_s puzzle',byusing two groups of parameters about the D_s^((*)) meson decay constants,that are f_D_s = 241 MeV,f_D_s~* = 272 MeV andf_D_s = 274 MeV,f_D_s~* = 312 MeV,to calculate the branching ratios for the considered decays.We find that the resultschange 30% by using these two different kinds of paramters.展开更多
Based on the assumption of a two-quark structure of the scalar meson f0（980） ,we calculate the branching ratios and CP-violating asymmetries for the four B → f0（980） π and B → f0（980） η^（＇） decays by empl...Based on the assumption of a two-quark structure of the scalar meson f0（980） ,we calculate the branching ratios and CP-violating asymmetries for the four B → f0（980） π and B → f0（980） η^（＇） decays by employing the perturbative QCD（pQCD） factorization approach. The leading order pQCD predictions for branching ratios are,Br（B^-→ f0（980） π^-） ～ 2.5×10^-6,Br（Bˉ^0 → f0（980） π^0） ～ 2.6×10^-7,Br（Bˉ^0 → f0（980） η） ～ 2.5×10^-7 and Br（Bˉ^0 → f0（980） η ） ～ 6.7×10^-7,which are consistent with both the QCD factorization predictions and the experimental upper limits.展开更多
By employing the perturbative QCD （pQCD） factorization approach, we calculate the full leading and the partial next-to-leading order （NLO） contributions to the seven B →πη（′） and η（′）η（′） decays. For...By employing the perturbative QCD （pQCD） factorization approach, we calculate the full leading and the partial next-to-leading order （NLO） contributions to the seven B →πη（′） and η（′）η（′） decays. For B^＋→ π＋η（′） decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir（π＋η）= 19±7% can also be accommodated by the pQCD approach.展开更多
In this decays B → D^（＊）l^-vl paper, we studied by using the the semileptonic ＂pQCD ＋ Lattice QCD＂ method. We made the extrapolation for the six relevant form factors by using the input values obtained from the...In this decays B → D^（＊）l^-vl paper, we studied by using the the semileptonic ＂pQCD ＋ Lattice QCD＂ method. We made the extrapolation for the six relevant form factors by using the input values obtained from the pQCD factorization approach in the low q2 region of 0 ≤ q^2≤≤mt^2 and the lattice QCD input at the endpoint q^2 = q^2max· We then calculated the ratios R（D） and R（D^＊） of the branching ratios B（B→ D^（＊）l^-vl） and found numeri- cally that （1） the ＂pQCD ＋ Lattice QCD＂ predictions for the branching ratios B（B → D^（＊）l^-vl） agree well with the measured values within one standard deviation; and （2） the ＂pQCD ＋ Lattice QCD＂ predictions for the ratios R（D^（＊）） are R（D） =0.037-0.037^＋0.038 and R（D^＊） = 20269-03020^＋03021;they agree with the data within 2σ deviation, in other words, one can explain the ＂R（D（^＊）-puzzle＂ in the framework of the Standard Model.展开更多
■→（D0,■）π+π-is induced by the b→c■s/b→u■s transitions,which can interfere if a CP-eigenstate DCP is formed.The interference contribution is sensitive to the CKM angle y.In this work,we study the S-wave π+...■→（D0,■）π+π-is induced by the b→c■s/b→u■s transitions,which can interfere if a CP-eigenstate DCP is formed.The interference contribution is sensitive to the CKM angle y.In this work,we study the S-wave π+π-contributions to the process in the perturbative QCD factorization.In the factorization framework,we adopt twomeson light-cone distribution amplitudes,whose normalization is parametrized by the S-wave time-like two-pion form factor with resonance contributions from f0（500）,f0（980）,f0（1500）,f0（1790）.We find that the branching ratio of ■→（D0,■）（π+π-）S is of the order of 10-6,and that significant interference exists in ■→DCP（π+π-）S.Future measurement could not only provide useful constraints on the CKM angle y,but would also be helpful for exploring the multi-body decay mechanism of heavy mesons.展开更多
The doubly weak transition b-dd■ is highly suppressed in the Standard Model,which makes it a potential channel for exploring new physics signals.We present a study of the exclusive two-body wrong sign weak decay ■...The doubly weak transition b-dd■ is highly suppressed in the Standard Model,which makes it a potential channel for exploring new physics signals.We present a study of the exclusive two-body wrong sign weak decay ■→K+π-,which belongs to this class,in the perturbative QCD framework.We perform a model independent analysis for various effective dimension-6 operators for which large effects are possible.We further analyze the considered process in the Randall-Sundrum model,including the custodially protected and the bulk-Higgs Randall-Sundrum models.Exploring the experimentally favored parameter space of these models leads to a large and significant enhancement of the decay rate compared to the Standard Model,which might be accessible in future experiments.We propose to search for the wrong sign decay ■→K+π-via flavor-tagged time-dependent analyses,which can be performed at LHCb and Belle-Ⅱ.展开更多
The decay channel H→γγ is an important channel for probing the properties of the Higgs boson.In this paper,we analyze its decay width by using the perturbative QCD corrections up to the αs4 order with the help of ...The decay channel H→γγ is an important channel for probing the properties of the Higgs boson.In this paper,we analyze its decay width by using the perturbative QCD corrections up to the αs4 order with the help of the principle of maximum conformality（PMC）.PMC has been suggested in literature for eliminating the conventional renormalization scheme-and-scale ambiguities.After applying PMC,we observe that an accurate renormalization scale independent decay width Γ（H→γγ） up to the N4 LO level can be achieved.Taking the Higgs mass,MH = 125.09±0.21 ±0.11 GeV,given by the ATLAS and CMS collaborations,we obtain Γ（H→γγ）|LHC = 9.3640.0750.076 KeV.展开更多
We study the semileptonic B/Bs→(D^(?),D^(?)s)lνl decays in the framework of the Standard Model(SM),by employing the perturbative QCD(PQCD)factorization formalism combined with the lattice QCD input for the relevant ...We study the semileptonic B/Bs→(D^(?),D^(?)s)lνl decays in the framework of the Standard Model(SM),by employing the perturbative QCD(PQCD)factorization formalism combined with the lattice QCD input for the relevant transition form factors.We calculate the branching ratios B(B(s)→D^(?)(s)lνl)with l=(e,μ,τ),the ratios of the branching fractions R(D^(?))and R(D^(?)s),and the physical observables Pτ(D^(?)(s)),FL(D?(s))and AFB(τ).The“PQCD+Lattice”predictions for B(B→D^(?)lνl)and R(D^(?))agree with the available experimental measurements within errors.For the ratios R(Ds)and R(D^?s),the"PQCD+Lattice"predictions agree with the other predictions.For Pτ(D^?)and FL(D^?),our theoretical predictions agree with the measured values within errors.Our theoretical predictions of the semileptonic B/Bs decays considered could be tested in the near future by the LHCb and Belle II experiments.展开更多
In this paper we study the semileptonic decays of Bc→（ηc, J/ψ）1-v1. We first evaluate the Bc→（ηc, J/ψ） transition form factors Fo（q2）, F＋（q2）, V（q2） and Ao,l,2（q2） by employing the pQCD factorizatio...In this paper we study the semileptonic decays of Bc→（ηc, J/ψ）1-v1. We first evaluate the Bc→（ηc, J/ψ） transition form factors Fo（q2）, F＋（q2）, V（q2） and Ao,l,2（q2） by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that： （a） the pQCD predictions for the values of the Bc→ηc, and Bc→J/ψ transition form factors agree well with those obtained by using other methods; （b） the pQCD predictions for the branching ratios of the considered decays are Br（B---qe-e（-））= （4.41_1.09）＋1＂22 10-3 Br（B----rl-） ---- （1.37_＋：337） x 10-3, Br（B：--J/kOe-e（li-,））=（iO.03＋：3）〉lO-3, and Br（B：--＊J/＇r-]T）----（2.92_0.34）10＋40 -3., and （c） we also define and calculate two ratios of the branching ratios Rn and Rj/v, which will be tested by LHCb and the forthcoming Super-B experiments.展开更多
We conducted a detailed study on the properties of the total decay width of the Higgs decay channel H→gg up toα_(s)^(6)-order QCD corrections by using the newly suggested infinite-order scale-setting approach,which ...We conducted a detailed study on the properties of the total decay width of the Higgs decay channel H→gg up toα_(s)^(6)-order QCD corrections by using the newly suggested infinite-order scale-setting approach,which is based on both the principle of maximum conformality and intrinsic conformality.This approach is called PMC_(∞) By using the PMC_(∞)approach,we observed that the conventional renormalization scale ambiguity in perturbative QCD calculation is eliminated,and the residual scale dependence due to unknown higher-order terms can also be highly suppressed.We then obtained an accurate perturbative QCD prediction on the total decay width,e.g.,Г(H→gg)|PMC_(∞)=336.42_(-6.92)^(+7.01)keV,where the errors are squared averages of those from all the mentioned error sources.展开更多
In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0（980）π^0, a0^＋ （980）π^-, a0^-（980）π^＋ and B^- → a0^0 （980）π^-, a0^- （980）π^0 by employin...In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0（980）π^0, a0^＋ （980）π^-, a0^-（980）π^＋ and B^- → a0^0 （980）π^-, a0^- （980）π^0 by employing the perturbative QCD （pQCD） factorization approach at the leading order. We found that （a） the pQCD predictions for the branching ratios are around （0.4-2.8） × 10^-6, consistent with currently available experimental upper limits; （b） the CP asymmetries of B^0→ a0^0（980）π^0 and B^- → a0^- （980）π^0 decays can be large, about （70-80）% for α= 100°.展开更多
Analyticity of nucleon form factors allows to derive sum rules which, using space-like and time-like data as input, can give unique information about behaviors in energy regions not experimentally accessible. Taking a...Analyticity of nucleon form factors allows to derive sum rules which, using space-like and time-like data as input, can give unique information about behaviors in energy regions not experimentally accessible. Taking advantage from new time-like data on proton-antiproton differential cross section and hence the possibility to separate electric and magnetic form factors also in the time-like region, we verify the consistency of the asymptotic behavior predicted by the perturbative QCD for the proton magnetic form factor.展开更多
文摘In this paper,the proton structure function F_(2)^(p)(x,Q^(2))at small-x is investigated using an analytical solution to the Balitsky–Kovchegov(BK)equation.In the context of the color dipole description of deep inelastic scattering(DIS),the structure function F_(2)^(p)(x,Q^(2))is computed by applying the analytical expression for the scattering amplitude N(k,Y)derived from the BK solution.At transverse momentum k and total rapidity Y,the scattering amplitude N(k,Y)represents the propagation of the quark-antiquark dipole in the color dipole description of DIS.Using the BK solution we extracted the integrated gluon density xg(x,Q^(2))and then compared our theoretical estimation with the LHAPDF global data fits,NNPDF3.1sx and CT18.Finally,we have investigated the behavior of F_(2)^(p)(x,Q^(2))in the kinematic region of 10^(-5)≤x≤10^(-2)and 2.5 GeV^(2)≤Q^(2)≤60 GeV^(2).Our predicted results for F_(2)^(p)(x,Q^(2))within the specified kinematic region are in good agreement with the recent high-precision data for F_(2)^(p)(x,Q^(2))from HERA(H1 Collaboration)and the LHAPDF global parametrization group NNPDF3.1sx.
基金Supported by the National Natural Science Foundation of China under Grant No.10575052,10605012,and 10735080
文摘By employing the perturbative QCD （pQCD） factorization approach, we calculate some important next- to-leading-order （NLO） contributions to the two-body charmless hadronic decays B^＋ →ρ^＋η（＇） and B^0 → ρ^0（ω, φ）η（＇）, induced by the vertex QCD corrections, the quark-loops as well as the chromo-magnetic penguins. From the numerical results and phenomenological analysis we find that （a） for B^± → ρ^±η（＇） （B^0 → ρ^0（ω, φ）η（＇）decays, the partial NLO contributions to branching ratios are small （large） in magnitude; and （b） the pQCD predictions for ACP^dir（B^± → ρ^±η（＇）） are consistent with the data, while the predicted .ACP（B^0 → ρ^0（ω）η（＇）） are generally large in magnitude and could be tested by the forthcoming LHCb experiments.
基金The project partly supported by National Natural Science Foundation of China
文摘The rare decays Bs^0（B^-0 s）→D^±π^-＋ can occur only via annihilation-type diagrams in the standard model. In this paper, we calculate branching ratios of these decays in perturbative QCD approach ignoring soft final state interaction. From our calculation, we find that their branching ratios are at O（10^-6） with large CP asymmetry, which may be measured in LHC-b experiment in the future.
文摘In this paper,we calculate the branching ratios for B^+→D_s^+η,B^+→D_s^+η′,B^+→D_s^(*+)η and B^+→D_s^(*+)η′decays by employing the perturbative QCD (pQCD) factorization approach.Under the two kinds of η-η′ mixingschemes,the quark-flavor mixing scheme and the singlet-octet mixing scheme,we find that the calculated branchingratios agree well with the currently available experimental upper limits.We also consider the so called 'f_D_s puzzle',byusing two groups of parameters about the D_s^((*)) meson decay constants,that are f_D_s = 241 MeV,f_D_s~* = 272 MeV andf_D_s = 274 MeV,f_D_s~* = 312 MeV,to calculate the branching ratios for the considered decays.We find that the resultschange 30% by using these two different kinds of paramters.
文摘Based on the assumption of a two-quark structure of the scalar meson f0（980） ,we calculate the branching ratios and CP-violating asymmetries for the four B → f0（980） π and B → f0（980） η^（＇） decays by employing the perturbative QCD（pQCD） factorization approach. The leading order pQCD predictions for branching ratios are,Br（B^-→ f0（980） π^-） ～ 2.5×10^-6,Br（Bˉ^0 → f0（980） π^0） ～ 2.6×10^-7,Br（Bˉ^0 → f0（980） η） ～ 2.5×10^-7 and Br（Bˉ^0 → f0（980） η ） ～ 6.7×10^-7,which are consistent with both the QCD factorization predictions and the experimental upper limits.
基金Supported by National Natural Science Foundation of China (10575052, 10735080)Specialized Research Fund for Doctoral Program of Higher Education (SRFDP) (20050319008)
文摘By employing the perturbative QCD （pQCD） factorization approach, we calculate the full leading and the partial next-to-leading order （NLO） contributions to the seven B →πη（′） and η（′）η（′） decays. For B^＋→ π＋η（′） decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir（π＋η）= 19±7% can also be accommodated by the pQCD approach.
基金supported by the National Natural Science Foundation of China(1123500511105115and 11505148)the key project of Henan’s Universities(15A140033)
文摘In this decays B → D^（＊）l^-vl paper, we studied by using the the semileptonic ＂pQCD ＋ Lattice QCD＂ method. We made the extrapolation for the six relevant form factors by using the input values obtained from the pQCD factorization approach in the low q2 region of 0 ≤ q^2≤≤mt^2 and the lattice QCD input at the endpoint q^2 = q^2max· We then calculated the ratios R（D） and R（D^＊） of the branching ratios B（B→ D^（＊）l^-vl） and found numeri- cally that （1） the ＂pQCD ＋ Lattice QCD＂ predictions for the branching ratios B（B → D^（＊）l^-vl） agree well with the measured values within one standard deviation; and （2） the ＂pQCD ＋ Lattice QCD＂ predictions for the ratios R（D^（＊）） are R（D） =0.037-0.037^＋0.038 and R（D^＊） = 20269-03020^＋03021;they agree with the data within 2σ deviation, in other words, one can explain the ＂R（D（^＊）-puzzle＂ in the framework of the Standard Model.
基金Supported in part by National Natural Science Foundation of China(11575110,11735010)Natural Science Foundation of Shanghai(15DZ2272100)Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education
文摘■→（D0,■）π+π-is induced by the b→c■s/b→u■s transitions,which can interfere if a CP-eigenstate DCP is formed.The interference contribution is sensitive to the CKM angle y.In this work,we study the S-wave π+π-contributions to the process in the perturbative QCD factorization.In the factorization framework,we adopt twomeson light-cone distribution amplitudes,whose normalization is parametrized by the S-wave time-like two-pion form factor with resonance contributions from f0（500）,f0（980）,f0（1500）,f0（1790）.We find that the branching ratio of ■→（D0,■）（π+π-）S is of the order of 10-6,and that significant interference exists in ■→DCP（π+π-）S.Future measurement could not only provide useful constraints on the CKM angle y,but would also be helpful for exploring the multi-body decay mechanism of heavy mesons.
基金Supported by National Science Foundation of China(11575151,11521505,11621131001)the Natural Science Foundation of Shandong Province(ZR2016JL001,ZR2019JQ04)+1 种基金the financial support from the Abdus Salam International Centre for Theoretical Physics during his visitfinancial support from CAS-TWAS president’s fellowship program 2014
文摘The doubly weak transition b-dd■ is highly suppressed in the Standard Model,which makes it a potential channel for exploring new physics signals.We present a study of the exclusive two-body wrong sign weak decay ■→K+π-,which belongs to this class,in the perturbative QCD framework.We perform a model independent analysis for various effective dimension-6 operators for which large effects are possible.We further analyze the considered process in the Randall-Sundrum model,including the custodially protected and the bulk-Higgs Randall-Sundrum models.Exploring the experimentally favored parameter space of these models leads to a large and significant enhancement of the decay rate compared to the Standard Model,which might be accessible in future experiments.We propose to search for the wrong sign decay ■→K+π-via flavor-tagged time-dependent analyses,which can be performed at LHCb and Belle-Ⅱ.
基金Supported in part by Natural Science Foundation of China(11625520,11547010,11847301,11705033)the Project of Guizhou Provincial Department of Science and Technology(2016GZ42963)+2 种基金the Key Project for Innovation Research Groups of Guizhou Provincial Department of Education(KY[2016]028,KY[2017]067)the Fundamental Research Funds for the Central Universities(2019CDJDWL0005)the graduate scientific research and innovation foundation of Chongqing(CYS19021)
文摘The decay channel H→γγ is an important channel for probing the properties of the Higgs boson.In this paper,we analyze its decay width by using the perturbative QCD corrections up to the αs4 order with the help of the principle of maximum conformality（PMC）.PMC has been suggested in literature for eliminating the conventional renormalization scheme-and-scale ambiguities.After applying PMC,we observe that an accurate renormalization scale independent decay width Γ（H→γγ） up to the N4 LO level can be achieved.Taking the Higgs mass,MH = 125.09±0.21 ±0.11 GeV,given by the ATLAS and CMS collaborations,we obtain Γ（H→γγ）|LHC = 9.3640.0750.076 KeV.
基金Supported by the National Natural Science Foundation of China (11775117,11235005).
文摘We study the semileptonic B/Bs→(D^(?),D^(?)s)lνl decays in the framework of the Standard Model(SM),by employing the perturbative QCD(PQCD)factorization formalism combined with the lattice QCD input for the relevant transition form factors.We calculate the branching ratios B(B(s)→D^(?)(s)lνl)with l=(e,μ,τ),the ratios of the branching fractions R(D^(?))and R(D^(?)s),and the physical observables Pτ(D^(?)(s)),FL(D?(s))and AFB(τ).The“PQCD+Lattice”predictions for B(B→D^(?)lνl)and R(D^(?))agree with the available experimental measurements within errors.For the ratios R(Ds)and R(D^?s),the"PQCD+Lattice"predictions agree with the other predictions.For Pτ(D^?)and FL(D^?),our theoretical predictions agree with the measured values within errors.Our theoretical predictions of the semileptonic B/Bs decays considered could be tested in the near future by the LHCb and Belle II experiments.
文摘In this paper we study the semileptonic decays of Bc→（ηc, J/ψ）1-v1. We first evaluate the Bc→（ηc, J/ψ） transition form factors Fo（q2）, F＋（q2）, V（q2） and Ao,l,2（q2） by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that： （a） the pQCD predictions for the values of the Bc→ηc, and Bc→J/ψ transition form factors agree well with those obtained by using other methods; （b） the pQCD predictions for the branching ratios of the considered decays are Br（B---qe-e（-））= （4.41_1.09）＋1＂22 10-3 Br（B----rl-） ---- （1.37_＋：337） x 10-3, Br（B：--J/kOe-e（li-,））=（iO.03＋：3）〉lO-3, and Br（B：--＊J/＇r-]T）----（2.92_0.34）10＋40 -3., and （c） we also define and calculate two ratios of the branching ratios Rn and Rj/v, which will be tested by LHCb and the forthcoming Super-B experiments.
基金Supported by the Chongqing Graduate Research and Innovation Foundation(CYB21045,ydstd1912)the Natural Science Foundation of China(12175025,12147102)the Fundamental Research Funds for the Central Universities(2020CQJQY-Z003,2021CDJZYJH-003)。
文摘We conducted a detailed study on the properties of the total decay width of the Higgs decay channel H→gg up toα_(s)^(6)-order QCD corrections by using the newly suggested infinite-order scale-setting approach,which is based on both the principle of maximum conformality and intrinsic conformality.This approach is called PMC_(∞) By using the PMC_(∞)approach,we observed that the conventional renormalization scale ambiguity in perturbative QCD calculation is eliminated,and the residual scale dependence due to unknown higher-order terms can also be highly suppressed.We then obtained an accurate perturbative QCD prediction on the total decay width,e.g.,Г(H→gg)|PMC_(∞)=336.42_(-6.92)^(+7.01)keV,where the errors are squared averages of those from all the mentioned error sources.
基金Supported by National Natural Science Foundation of China (10575052,10735080)
文摘In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0（980）π^0, a0^＋ （980）π^-, a0^-（980）π^＋ and B^- → a0^0 （980）π^-, a0^- （980）π^0 by employing the perturbative QCD （pQCD） factorization approach at the leading order. We found that （a） the pQCD predictions for the branching ratios are around （0.4-2.8） × 10^-6, consistent with currently available experimental upper limits; （b） the CP asymmetries of B^0→ a0^0（980）π^0 and B^- → a0^- （980）π^0 decays can be large, about （70-80）% for α= 100°.
文摘Analyticity of nucleon form factors allows to derive sum rules which, using space-like and time-like data as input, can give unique information about behaviors in energy regions not experimentally accessible. Taking advantage from new time-like data on proton-antiproton differential cross section and hence the possibility to separate electric and magnetic form factors also in the time-like region, we verify the consistency of the asymptotic behavior predicted by the perturbative QCD for the proton magnetic form factor.
