Search for the charmed pentaquark candidate ${\Theta }_c(3100{)}^0$ in $e^{+}{e}^{-}$ annihilations at $\sqrt{s}=10.58\mathrm{GeV}$

We search for the charmed pentaquark candidate reported by the H1 collaboration, the ${\Theta }_c(3100{)}^0$, in $e^{+}{e}^{-}$ interactions at a center-of-mass (c.m.) energy of 10.58 GeV, using $124{\mathrm{fb}}^{-1}$ of data recorded with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ facility at SLAC. We find no evidence for such a state in the same $p{D}^{*-}$ decay mode reported by H1, and we set limits on its production cross section times branching fraction into $p{D}^{*-}$ as a function of c.m. momentum. The corresponding limit on its total rate per $e^{+}{e}^{-}\to q\overline{q}$ event, times branching fraction, is about 3 orders of magnitude lower than rates measured for the charmed ${\mathit{\Lambda }}_c$ and ${\mathit{\Sigma }}_c$ baryons in such events.

Figure 1

(a) Distributions of the invariant mass difference between the $D^{*-}$ and ${\overline{D}}^0$ combinations in $X\to p{D}^{*-}$ candidates in the data, for the two ${\overline{D}}^0$ decay modes. (b) Distribution of the reconstructed momentum of the $D^{*-}$ in the $e^{+}{e}^{-}$ c.m. frame for $p{D}^{*-}$ candidates in the data (histogram); the dashed (dotted) line represents the $D^{*-}$ spectra measured in $\mathit{{\rm Y}}(4S)$ decays ($e^{+}{e}^{-}\to c\overline{c}$ events) scaled as described in the text.

Figure 2

Invariant mass distributions for ${\Theta }_c(3100{)}^0$ candidates in the data in the (black) $K^{+}{\pi }^{-}$ and (gray) $K^{+}{\pi }^{-}{\pi }^{-}{\pi }^{+}$ decay modes, over a wide mass range and (inset) in the region near $3100\mathrm{MeV}/c^2$.

Figure 3

${\Theta }_c(3100{)}^0$ yields from fits to the $m_{p{D}^{*}}$ distributions for the (left) $p{K}^{+}{\pi }^{-}{\pi }_s^{-}$ and (right) $p{K}^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}{\pi }_s^{-}$ decay modes, assuming a mass of $3099\mathrm{MeV}/c^2$ and a natural width of $\Gamma =1\mathrm{MeV}$ (black) or $\Gamma =28\mathrm{MeV}$ (gray).

Figure 4

Product of the ${\Theta }_c(3100{)}^0$ differential production cross section and its branching fraction to $p{D}^{*-}$ (symbols) and corresponding 95% CL upper limits (lines), assuming natural widths of $\Gamma =1\mathrm{MeV}$ (solid) and $\Gamma =28\mathrm{MeV}$ (open/dashed), as functions of c.m. momentum.