arXiv subjects

Tianhong Wang

Publications and source records attributed to Tianhong Wang.

74 records · Page 5Linked to original sources

arXiv2013

Annihilation rate of $2^{-+}$ charmonium and bottomonium

The $1^1D_2 (c\bar c)$ state is the ground state of spin-singlet D-wave charmonia. Although it has not been found yet, the experimental data accumulate rapidly. This charmonium attracts more and more attention, especially when the BaBar Collaboration finds that the X(3872) particle has negative parity. In this paper we calculate the double-gamma and double-gluon annihilation processes of $^1D_2$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. We find the relativistic corrections make the decay widths of $1^1D_2 (c\bar c)$ 2$\sim$5 times smaller than the non-relativistic results. If this state is below the $D^0{D^{0}}^\ast$ threshold, we can use the sum of annihilation widths and EM transition widths to estimate the total decay width. Our result for $1{^1D_2} (c\bar c)$ with $m=3820$ GeV is $Γ= 432$ keV. The dominant decay channel $1^1D_2 (c\bar c)\to h_c γ$, whose branching ratio is about 90%, can be used to discover this state.

hep-ph↗

arXiv2012

EM Decay of X(3872) as the $1{^1D_2}(2^{-+})$ charmonium

The recently BaBar results raise the possibility that X(3872) has negative parity. This makes people reconsider assigning X(3872) to the $1{^1D_2}(c\bar c)$ state. In this paper we give a general form of the wave function of $2^{-+}$ mesons. By solving the instantaneous Bethe-Salpeter equation, we get the mass spectrum and corresponding wave functions. We calculate electromagnetic decay widths of the first $2^{-+}$ state which we assume to be the X(3872) particle. The results are $Γ(2^{-+}(3872)\rightarrow J/ψγ) = 1.59^{+0.53}_{-0.42}$ keV, $Γ(2^{-+}(3872)\rightarrow ψ(2S)γ) = 2.87^{+1.46}_{-0.97}$ eV and $Γ(2^{-+}(3872)\rightarrow ψ(3770)γ) = 0.135^{+0.066}_{-0.047}$ keV. The ratio of branch fractions of the second and first channel is about 0.002, which is inconsistent with the experimental value $3.4\pm 1.4$. So X(3872) is unlikely to be a $2^{-+}$ charmonium state. In addition, we obtain a relatively large decay width for $2^{-+}(3872)\rightarrow h_cγ$ channel which is $392^{+62}_{-111}$ keV.

hep-ph↗