Study of the $h_c$($1^1{P}_1$) meson via $\psi (2S)\to {\pi }^0{h}_c$ decays at BESIII

Abstract

Using 448 million $\psi (2S)$ events, the spin-singlet $P$-wave charmonium state $h_c$(1${}^1{P}_1$) is studied via the $\psi (2S)\to {\pi }^0{h}_c$ decay followed by the $h_c\to \gamma {\eta }_c$ transition. The branching fractions are measured to be ${\mathcal{B}}_{\mathrm{Inc}}(\psi (2S)\to {\pi }^0{h}_c)\times {\mathcal{B}}_{\mathrm{Tag}}(h_c\to \gamma {\eta }_c)=(4.22_{-0.26}^{+0.27}\pm 0.19)\times 10^{-4}$ , ${\mathcal{B}}_{\mathrm{Inc}}(\psi (2S)\to {\pi }^0{h}_c)=(7.32\pm 0.34\pm 0.41)\times 10^{-4}$, and ${\mathcal{B}}_{\mathrm{Tag}}(h_c\to \gamma {\eta }_c)=(57.66_{-3.50}^{+3.62}\pm 0.58)\%$, where the uncertainties are statistical and systematic, respectively. The $h_c$(1${}^1{P}_1$) mass and width are determined to be $M=(3525.32\pm 0.06\pm 0.15)\mathrm{MeV}/{\mathrm{c}}^2$ and $\Gamma =(0.78_{-0.24}^{+0.27}\pm 0.12)\mathrm{MeV}$. Using the center of gravity mass of the three ${\chi }_{cJ}$(1${}^3{P}_J$) mesons ($M(c.o.g.)$), the $1P$ hyperfine mass splitting is estimated to be ${\Delta }_{\mathrm{hyp}}=M(h_c)-M(c.o.g.)=(0.03\pm 0.06\pm 0.15)\mathrm{MeV}/{\mathrm{c}}^2$, which is consistent with the expectation that the $1P$ hyperfine splitting is zero at the lowest-order.

References in corpus (1)

• Evidence of Two Resonant Structures in $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$

Cited by in corpus (8)

• Observation of Three Resonant Structures in the Cross Section of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$
• Shedding light on charmonium
• QCD analysis of the $P$-wave charmonium electromagnetic Dalitz decays $h_c\to {\eta }^{(\prime )}{\ell }^{+}{\ell }^{-}$
• Observation of the Electromagnetic Dalitz Transition $h_c\to e^{+}{e}^{-}{\eta }_c$
• Observation of the decay $h_c\to 3({\pi }^{+}{\pi }^{-}){\pi }^0$
• Search for $h_c\to {\pi }^{+}{\pi }^{-}J/\psi$ via $\psi (3686)\to {\pi }^0{h}_c$
• Measurements of the branching fractions of the $P$-wave charmonium spin-singlet state $h_c{(}^1{P}_1)\to h^{+}{h}^{-}{\pi }^0/\eta$
• Observation of Charmonium $h_c$ Radiative Decays to Multiple Light Hadrons and the Tensor State $f_2(1270)$