Search for the doubly charmed baryon $\hat{I}{\text{c◯}}_{cc}^{+}$

Abstract

A search for the doubly charmed baryon $\hat{I}{\text{c◯}}_{cc}^{+}$ with the decay mode $\hat{I}{\text{c◯}}_{cc}^{+}\to \hat{I}{ž}_c^{+}{K}^{-}\ddot{I}{€}^{+}$ is performed using proton-proton collision data at a centre-of-mass energy of 13$\mathrm{Te}\mathrm{V}$ collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. No significant signal is observed within the invariant mass range of 3.6 to 4.0$\mathrm{Ge}\mathrm{V}/c^2$. Upper limits are set on the ratio $R$ of the production cross-section times the total branching fraction of the $\hat{I}{\text{c◯}}_{cc}^{+}\to \hat{I}{ž}_c^{+}{K}^{-}\ddot{I}{€}^{+}$ decay with respect to the $\hat{I}{ž}_{cc}^{++}\to \hat{I}{›}_c^{+}{K}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+}$ decay. Upper limits at 95% credibility level for $R$ in the range $0.005$ to $0.11$ are obtained for different hypotheses on the $\hat{I}{\text{c◯}}_{cc}^{+}$ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15$\mathrm{Ge}\mathrm{V}/c$.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-011.html (LHCb public pages)