Research On The Decay And Production Of Excited Scalar And Tensor D Mesons

The D mesons containing charm quarks are always important subjects to study in heavy flavor physics.In the last decades,many charmed resonances have been found experimentally and cataloged.With the increasing collision energy of accelerator experiments and more data accumulated,more attention has moved to heavier excited states.However,many excited states predicted by theoretical models are still not confirmed in the experiments and some resonances observed in the experiment have not get appropriately assignedin the theoretical mesons spectra.In recent years,BaBar,LHCb,and other collaborations announced their observations of several new charmed resonances especially the states whose mass are around 3000 MeV.The quantum number and parity of these states are not completely identified.In this work,we mainly focus on DJ*(3000)and D2*(3000)which are generally considered as excited D mesons of scalar states and tensor states respectively.Studying their decay and production processes can help to identify their quantum number and detect higher excited states in the future.We first calculate the OZI allowed two-body strong decays of scalar D mesons.The wave functions of corresponding initial states and final states are obtained by the Bethe-Salpeter(BS)method.The significant influence of relativistic effects on excited states is included in the wave functions.By using Partially conserved axial-vector current(PCAC)rules,the form factors of transition matrix elements and decay widths can be calculated.Then we apply the same approach to the 2P excited states of scalar D mesons.For those decay channels including light vector mesons,an effective Lagrangian method is also introduced to replace the PCAC rule to calculate the transition matrix element.We try to cover all possible two-body strong decay channels and estimate the total width.Our results are close to the recent experimental observation of DJ*(3000).Meanwhile,we also consider the decay widths change with the masses of states and analyse the difference between 2P excited state case and ground state case.Calculations of B mesons semi-leptonic and non-leptonic decays to scalar D mesons are included in this work.The BS approach is also used to derive the hadronic transition matrix elements and form factors.Then the partial widths and branching fractions of involved channels are computed numerically.The lepton spectra of differential widths for semi-leptonic decays are presented.Taking DJ*(3000)as 2P excited state of scalar D mesons,the semi-leptonic and non-leptonic production ratios from B decays are of the order of 10-6～10-4.The special node structure of wave functions for excited states probably results in this abnormal uncertainty.Based on the possible mass value of 2P state,the mass of 3P states is also estimated and its production rates get the order of 10-5 which reach some experimental detection threshold.It is likely to observe higher excited states of scalar D mesons in future experiments.For D2*(3000),the possible tensor candidates include not only P wave but also F wave.Considering the present mass from preliminary measurement and theoretical mesons spectra,23P2,13F3,33P2,and 23F2 states in 2+family are all the possible candidates.We also consider all final states of two-body strong decays as far as possible and give the partial width of each channel.The widths of these four assignments are totally different.With the same mass value input,our results show that the widths of 33P2 and 33F2 are narrower,23P2 state gets broader,and 13F2 is the broadest one.23P2 and 23F2 enter the margin of present experimental data.The ratio of some important channels and the relation between widths and masses are also presented.The analyses in this work can provide essential assistance to identify D2*(3000)and measure higher excited charmed states.