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
The nonleptonic two body Bu;d;s;c decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on kTfactorization.The decay modes with a tensor meson emitted,are prohibited ...The nonleptonic two body Bu;d;s;c decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on kTfactorization.The decay modes with a tensor meson emitted,are prohibited in naive factorization,since the emission diagram with a tensor meson produced from vacuum is vanished.While contributions from the so-called hard scattering emission diagrams and annihilation type diagrams are important and calculable in the perturbative QCD approach.The branching ratios of most decays are in the range of 10 4–10 8,which are bigger by 1 or 2 orders of magnitude than the predictions given by the naive factorization,but consistent with the predictions from the QCD factorization and the recent experimental measurements.We also give the predictions for the direct CP asymmetries,some of which are large enough for the future experiments to measure.We also find that,even with a small mixing angle,the mixing between f2and f02can bring remarkable changes to both branching ratios and the direct CP asymmetries for some decays involving fe0T2mesons.For decays with a vector meson and a tensor meson in final states,we predict a large percentage of transverse polarization contributions due to the contributions of the orbital angular momentum of the tensor mesons.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
We calculate the branching ratios of pure annihilation type decays B0→Ds- K2＊＋ and Bs→Da2 using the perturbative QCD approach based on kT factorization. The branching ratios are predicted to be （60.6-16.5-10.4-2....We calculate the branching ratios of pure annihilation type decays B0→Ds- K2＊＋ and Bs→Da2 using the perturbative QCD approach based on kT factorization. The branching ratios are predicted to be （60.6-16.5-10.4-2.1＋17.3＋4.3＋3.2 ）× 10-6 for B0→Ds- K2＊＋, （1.1-0.4-0.2-0.1＋0.4＋0.1＋0.1）×10-6 for Bs→D0a20 and （2.3-0.8-0.4-0.1＋0.8＋0.2＋0.1）×10-6 for Bs→D-a2＋. They are large enough to be measured in the ongoing experiment. Due to the shortage of contributions from penguin operators, there are no direct CP asymmetries for these decays in the Standard Model. We also derive simple relations among these decay channels to reduce theoretical uncertainties for the experiments ,to test the accuracy of theory, and to search for a signal of new physics.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
We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form fa...We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD results.We find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±0.01.The theoretical predictions of RJ/ψagree with the measurements within the errors.The other predictions could be tested by the LHCb experiment in the near future.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
Within the framework of the perturbative quantum chromodynamics （PQCD） approach, we study the charmless two-body decays B→a1（1260）K＊, bl （1235）K＊. Using the decay constants and the light-cone distribution amp...Within the framework of the perturbative quantum chromodynamics （PQCD） approach, we study the charmless two-body decays B→a1（1260）K＊, bl （1235）K＊. Using the decay constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results. （a） Our predictions for the branching ratios are consistent with the QCD factorization （QCDF） results within errors, but much larger than the naive factorization approach calculation values. （b） We predict that the anomalous polarizations occurring in the decays B→ФK＊, pK＊ also happen in B→a1K＊ decays, while they do not happen in B→blK＊ decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→alK＊ decays, while they are not sensitive to the polarizations for the B→blK＊ decays. （c） Our predictions for the direct CP-asymmetries agree well with the QCDF results within errors. The decays B-0→b＋K＊-, B-→b0/1K＊- have larger direct CP-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.展开更多
By employing the perturbative QCD（PQCD） factorization approach, we study the quasi-two-body B（s）^0→ηc（2S）π^＋π^- decays, where the pion pair comes from the S-wave resonance f0（X）. The Breit-Wigner formula ...By employing the perturbative QCD（PQCD） factorization approach, we study the quasi-two-body B（s）^0→ηc（2S）π^＋π^- decays, where the pion pair comes from the S-wave resonance f0（X）. The Breit-Wigner formula for the f0（500） and f0（1500） resonances and the Flatt′e model for the f0（980） resonance are adopted to parameterize the time-like scalar form factors in the two-pion distribution amplitudes. As a comparison, Bugg＇s model is also used for the wide f0（500） in this work. For decay rates, we found the following PQCD predictions：（a）-B（Bs^0 →ηc（2S）f0（X）[π^＋π^-]s）= 2.67-1.08^＋1.78 ×10^-5 when the contributions from f0（980） and f0（1500） are all taken into account;（b）B（B0→η-c（2S）f0（500）[π^＋π^-]s） = 1.40（-0.56）（＋0.92） ×10^-6 in the Breit-Wigner model and 1.53（-0.61）^（＋0.97） ×10^-6 in Bugg＇s model.展开更多
Within the framework of the perturbative QCD approach,we calculate the time-like B（c ）Bc（Bc＊）form factors F（Q^2）and A2（Q^2）.We include relativistic corrections and QCD corrections,either of which can give abo...Within the framework of the perturbative QCD approach,we calculate the time-like B（c ）Bc（Bc＊）form factors F（Q^2）and A2（Q^2）.We include relativistic corrections and QCD corrections,either of which can give about20%correction to the leading-order contribution,but there are cancellation effects between them.We calculate the cross sections of the e^＋e^-→Bc-Bc＋（Bc＊＋）processes.The cross sections are enhanced at the Z pole to beσ^（P P）（Q=m Z）～1.3×10^-5pb andσ^（P V）（Q=m Z）～2.5×10^-5pb,which are still too small to be detected by proposed e~＋e^-colliders such as the Circular Electron Positron Collider.展开更多
In this paper,we calculated the branching ratios and direct CP violation of the four B→Kπ decays with the inclusion of all currently known next-to-leading order（NLO） contributions by employing the perturbative QCD...In this paper,we calculated the branching ratios and direct CP violation of the four B→Kπ decays with the inclusion of all currently known next-to-leading order（NLO） contributions by employing the perturbative QCD（pQCD） factorization approach.We found that（a） Besides the 10%enhancement from the NLO vertex corrections,the quark-loops and magnetic penguins,the NLO contributions to the form factors can provide an additional^15%enhancement to the branching ratios,and lead to a very good agreement with the data;（b） The NLO pQCD predictions are A_（CP）^（dir）（B^0→K~＋π~0）=（-6.5±3.1）%and A_（CP）^（dir）（B~＋→K~＋π~0）=（2.2±2.0）%,become well consistent with the data due to the inclusion of the NLO contributions.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 present the performance of the ALICE muon spectrometer for measuring the charm and beauty inclusive p t differential production cross sections via single muons and unlike-sign dimuons in proton-proton collisions at...We present the performance of the ALICE muon spectrometer for measuring the charm and beauty inclusive p t differential production cross sections via single muons and unlike-sign dimuons in proton-proton collisions at√ s = 14 TeV.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
In the two-quark model supposition for K0＊（1430）, which can be viewed as either the first excited state （ScenarioⅠ） or the lowest lying state （Scenario Ⅱ）, the branching ratios and the direct CP-violating asy...In the two-quark model supposition for K0＊（1430）, which can be viewed as either the first excited state （ScenarioⅠ） or the lowest lying state （Scenario Ⅱ）, the branching ratios and the direct CP-violating asymmetries for decays s0 → K0＊0（1430）η （’） are studied by employing the perturbative QCD factorization approach. We find the following results： （a） The CP averaged branching ratios ofs0 → K0＊0 （1430）η ands0→ K0＊0（1430）η’ are small and both in the order of 10-7 . If one views K0＊ （1430） as the lowest lying state, B（s0→K0＊0（1430）η） ≈ 3.9×10-7 and B（s0→K0＊0（1430）η’） ≈ 7.8×10-7.（b） While the direct CP-violating asymmetries of these two decays are not small： if we still take the parameters of K0＊ （1430） in scenario , ACPdir（s0→K0＊0（1430）η） ≈ 56.2% and ACPdir（s0→ K0＊0（1430）η’） ≈ 42.4%. （c） The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.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
■→（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
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
In this work,we investigate the quasi-two-body decays B_(c)→D^(*)h→Dπhwithh=(K^(0),π^(0),η,η′)using the perturbative QCD(PQCD)approach.The description of final state interactions of the Dπpair is achieved thro...In this work,we investigate the quasi-two-body decays B_(c)→D^(*)h→Dπhwithh=(K^(0),π^(0),η,η′)using the perturbative QCD(PQCD)approach.The description of final state interactions of the Dπpair is achieved through the two-meson distribution amplitudes(DAs),which are normalized to the time-like form factor.The PQCD predictions on the branching ratios of the quasi-two-body decays B_(c)→D^(*)h→Dπh show an obvious hierarchy:Br(B^(+)_(c)→D^(∗+)K^(0)→D^(0)π^(+)K^(0))=(5.22^(+0.86)_(-0.74))×10^(-6),Br(B^(+)_(c)→D^(∗+)π^(0)→D^(0)π^(+)π^(0))=(0.93±0.26)×10^(-7),Br(B^(+)_(c)→D^(∗+)η→D^(0)π^(+)η)=(2.83^(+0.59)_(-0.52))×10^(-8)and Br(B^(+)_(c)→D^(∗+)η′→D^(0)π^(+)η′)=(1.89+0.40-0.36)×10^(-8).From the invariant mass m Dπ-dependence of the decay spectrum for each channel,one can find that the branching fraction is concentrated in a narrow region around the D*pole mass.Thus,one can obtain the branching ratios for the corresponding two-body decays B_(c)→D^(*+)h under the narrow-width approximation.We find that the branching ratios of the decays B_(c)→D^(*+)h are consistent with the previous PQCD calculations within errors.These predictions will be tested in future experiments.展开更多
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 in part by the Foundation of Yantai University (WL07052)the National Natural Science Foundation of China (11375208,11228512,11235005 and 11175151)
文摘The nonleptonic two body Bu;d;s;c decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on kTfactorization.The decay modes with a tensor meson emitted,are prohibited in naive factorization,since the emission diagram with a tensor meson produced from vacuum is vanished.While contributions from the so-called hard scattering emission diagrams and annihilation type diagrams are important and calculable in the perturbative QCD approach.The branching ratios of most decays are in the range of 10 4–10 8,which are bigger by 1 or 2 orders of magnitude than the predictions given by the naive factorization,but consistent with the predictions from the QCD factorization and the recent experimental measurements.We also give the predictions for the direct CP asymmetries,some of which are large enough for the future experiments to measure.We also find that,even with a small mixing angle,the mixing between f2and f02can bring remarkable changes to both branching ratios and the direct CP asymmetries for some decays involving fe0T2mesons.For decays with a vector meson and a tensor meson in final states,we predict a large percentage of transverse polarization contributions due to the contributions of the orbital angular momentum of the tensor mesons.
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.
基金Supported by National Natural Science Foundation of China （11075168）
文摘We calculate the branching ratios of pure annihilation type decays B0→Ds- K2＊＋ and Bs→Da2 using the perturbative QCD approach based on kT factorization. The branching ratios are predicted to be （60.6-16.5-10.4-2.1＋17.3＋4.3＋3.2 ）× 10-6 for B0→Ds- K2＊＋, （1.1-0.4-0.2-0.1＋0.4＋0.1＋0.1）×10-6 for Bs→D0a20 and （2.3-0.8-0.4-0.1＋0.8＋0.2＋0.1）×10-6 for Bs→D-a2＋. They are large enough to be measured in the ongoing experiment. Due to the shortage of contributions from penguin operators, there are no direct CP asymmetries for these decays in the Standard Model. We also derive simple relations among these decay channels to reduce theoretical uncertainties for the experiments ,to test the accuracy of theory, and to search for a signal of new physics.
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.
基金Supported by the National Natural Science Foundation of China(11775117,11235005)
文摘We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD results.We find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±0.01.The theoretical predictions of RJ/ψagree with the measurements within the errors.The other predictions could be tested by the LHCb experiment in the near future.
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 National Natural Science Foundation of China(11147004,11347030)Program of Youthful Key Teachers in University of Henan Province(001166)by Foundation of Henan Educational Committee(14HASTIT037)
文摘Within the framework of the perturbative quantum chromodynamics （PQCD） approach, we study the charmless two-body decays B→a1（1260）K＊, bl （1235）K＊. Using the decay constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results. （a） Our predictions for the branching ratios are consistent with the QCD factorization （QCDF） results within errors, but much larger than the naive factorization approach calculation values. （b） We predict that the anomalous polarizations occurring in the decays B→ФK＊, pK＊ also happen in B→a1K＊ decays, while they do not happen in B→blK＊ decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→alK＊ decays, while they are not sensitive to the polarizations for the B→blK＊ decays. （c） Our predictions for the direct CP-asymmetries agree well with the QCDF results within errors. The decays B-0→b＋K＊-, B-→b0/1K＊- have larger direct CP-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.
基金Supported by National Natural Science Foundation of China(11235005,11547038)
文摘By employing the perturbative QCD（PQCD） factorization approach, we study the quasi-two-body B（s）^0→ηc（2S）π^＋π^- decays, where the pion pair comes from the S-wave resonance f0（X）. The Breit-Wigner formula for the f0（500） and f0（1500） resonances and the Flatt′e model for the f0（980） resonance are adopted to parameterize the time-like scalar form factors in the two-pion distribution amplitudes. As a comparison, Bugg＇s model is also used for the wide f0（500） in this work. For decay rates, we found the following PQCD predictions：（a）-B（Bs^0 →ηc（2S）f0（X）[π^＋π^-]s）= 2.67-1.08^＋1.78 ×10^-5 when the contributions from f0（980） and f0（1500） are all taken into account;（b）B（B0→η-c（2S）f0（500）[π^＋π^-]s） = 1.40（-0.56）（＋0.92） ×10^-6 in the Breit-Wigner model and 1.53（-0.61）^（＋0.97） ×10^-6 in Bugg＇s model.
基金Supported by Natural Science Foundation of Shandong Province,China(ZR2015AQ006)National Natural Science Foundation of China(11521505,11621131001,11447009,11505098,11765012)R.H.Li is partly supported by the plan of Young Creative Talents under the Talent of the Prairie project of the Inner Mongolia
文摘Within the framework of the perturbative QCD approach,we calculate the time-like B（c ）Bc（Bc＊）form factors F（Q^2）and A2（Q^2）.We include relativistic corrections and QCD corrections,either of which can give about20%correction to the leading-order contribution,but there are cancellation effects between them.We calculate the cross sections of the e^＋e^-→Bc-Bc＋（Bc＊＋）processes.The cross sections are enhanced at the Z pole to beσ^（P P）（Q=m Z）～1.3×10^-5pb andσ^（P V）（Q=m Z）～2.5×10^-5pb,which are still too small to be detected by proposed e~＋e^-colliders such as the Circular Electron Positron Collider.
基金Supported by National Natural Science Foundation of China(10975074,11235005)
文摘In this paper,we calculated the branching ratios and direct CP violation of the four B→Kπ decays with the inclusion of all currently known next-to-leading order（NLO） contributions by employing the perturbative QCD（pQCD） factorization approach.We found that（a） Besides the 10%enhancement from the NLO vertex corrections,the quark-loops and magnetic penguins,the NLO contributions to the form factors can provide an additional^15%enhancement to the branching ratios,and lead to a very good agreement with the data;（b） The NLO pQCD predictions are A_（CP）^（dir）（B^0→K~＋π~0）=（-6.5±3.1）%and A_（CP）^（dir）（B~＋→K~＋π~0）=（2.2±2.0）%,become well consistent with the data due to the inclusion of the NLO contributions.
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 NSFC (10875051,10635020)State Key Development Program of Basic Research of China (2008CB317106)+1 种基金Key Project of Chinese Ministry of Education (306022,IRT0624)Programme of Introducing Talents of Discipline to Universitiesnder of China (B08033)
文摘We present the performance of the ALICE muon spectrometer for measuring the charm and beauty inclusive p t differential production cross sections via single muons and unlike-sign dimuons in proton-proton collisions at√ s = 14 TeV.
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°.
基金Supported by National Natural Science Foundation of China (11147004)Foundation of Henan University of Technology(2009BS038)
文摘In the two-quark model supposition for K0＊（1430）, which can be viewed as either the first excited state （ScenarioⅠ） or the lowest lying state （Scenario Ⅱ）, the branching ratios and the direct CP-violating asymmetries for decays s0 → K0＊0（1430）η （’） are studied by employing the perturbative QCD factorization approach. We find the following results： （a） The CP averaged branching ratios ofs0 → K0＊0 （1430）η ands0→ K0＊0（1430）η’ are small and both in the order of 10-7 . If one views K0＊ （1430） as the lowest lying state, B（s0→K0＊0（1430）η） ≈ 3.9×10-7 and B（s0→K0＊0（1430）η’） ≈ 7.8×10-7.（b） While the direct CP-violating asymmetries of these two decays are not small： if we still take the parameters of K0＊ （1430） in scenario , ACPdir（s0→K0＊0（1430）η） ≈ 56.2% and ACPdir（s0→ K0＊0（1430）η’） ≈ 42.4%. （c） The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.
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 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 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Supported by the National Natural Science Foundation of China(11347030)the Program of Science and Technology Innovation Talents in Universities of Henan Province,China(14HASTIT037)the Natural Science Foundation of Henan Province,China(232300420116)
文摘In this work,we investigate the quasi-two-body decays B_(c)→D^(*)h→Dπhwithh=(K^(0),π^(0),η,η′)using the perturbative QCD(PQCD)approach.The description of final state interactions of the Dπpair is achieved through the two-meson distribution amplitudes(DAs),which are normalized to the time-like form factor.The PQCD predictions on the branching ratios of the quasi-two-body decays B_(c)→D^(*)h→Dπh show an obvious hierarchy:Br(B^(+)_(c)→D^(∗+)K^(0)→D^(0)π^(+)K^(0))=(5.22^(+0.86)_(-0.74))×10^(-6),Br(B^(+)_(c)→D^(∗+)π^(0)→D^(0)π^(+)π^(0))=(0.93±0.26)×10^(-7),Br(B^(+)_(c)→D^(∗+)η→D^(0)π^(+)η)=(2.83^(+0.59)_(-0.52))×10^(-8)and Br(B^(+)_(c)→D^(∗+)η′→D^(0)π^(+)η′)=(1.89+0.40-0.36)×10^(-8).From the invariant mass m Dπ-dependence of the decay spectrum for each channel,one can find that the branching fraction is concentrated in a narrow region around the D*pole mass.Thus,one can obtain the branching ratios for the corresponding two-body decays B_(c)→D^(*+)h under the narrow-width approximation.We find that the branching ratios of the decays B_(c)→D^(*+)h are consistent with the previous PQCD calculations within errors.These predictions will be tested in future experiments.
