Production And Decays Of X（3872） Meson As The χ_c1（2P）

The striking result of the years since 2003 in heavy flavour sector is the observation of a series of charmoniumlike exotics,labeled as X,Y or Z.As the first of the XY Z states to be discovered,the X(3872)is also the one gets the most ubiquitously and thoroughly studied both in experiment section and theory aspect.But its nature is still obscure to date.Recently,BESIII and LHCb reported their measurement results on EM Dalitz decaysχc1→ J/ψe+e-and χc1→ J/ψμ+μ-,respectively.According to their papers,the detection of the same decay channels of X(3872)has been proposed on their experiment schedules.That’s quite encouraging news,since the precise measurement of this decay mode can possibly disentangle its nature from various exotic pictures.In this work,we perform a systematical study on production and decays of X(3872)with χc1(2P)assignment in an instantaneous approximation of the Bethe-Salpeter equation approach.In the part of production,both the semileptonic decay channels and the nonleptonic decay channels are calculated in Bcdecays.Nevertheless,those channels decaying to χc1and χc1(3P)get contained in our calculation as well.For χc1final state,the total branching ratio in Bcdecay is 5.47 × 10-3.This result is in consistent with our previous work.For X(3872)final state,the total branching ratio in Bcdecay is given as6.20 × 10-4,expected to get tested by experiment in the future.For χc1(3P)final state,the total branching ratio in Bcdecay is 8.98 × 10-5in our prediction.On the other hand,we try to probe the nature of X(3872)via its weak decay,twobody strong decay and electromagnetic decay.With weak interaction,the dominant decay modes are supposed to be X(3872)→ Ds(D*s).And our calculation obtains two tiny total branching ratios for this two decay modes as 4.14 × 10-11(8.72 × 10-11),respectively.When it comes to two-body strong decay,the channel D0 ˉD*0 is the only one permitted by the OZI machanism.We accomplish the curve of its branching ratio moving with the mass of the χc1(2P),and we find this theoretical branching ratio can get in agreement with the experimental data when we choose proper parameters in our calculation.Finally,the electromagnetic decay is in consideration.In our previous work,the radiative E1 decays of X(3872)have been calculated and tested by later experimental results.So we study the EM Dalitz decays of X(3872)and χc1this time.In the section of χc1→ J/ψl+l-,the theoretical lepton spectra are in good agreement with experimental spectra.And we do believe our results in X(3872)section can get confirmed by BESIII and LHCb experiment in near future.In conclusion,our results support X(3872)to be the χc1(2P),and it is hoped to get more experiment evidence in near future.