Search for $\bar{\mathrm{\Lambda }}$-$\mathrm{\Lambda }$ oscillations in the decay $J\mathrm{/}\psi \to p{K}^{-}\bar{\mathrm{\Lambda }}+c\mathrm{.}c\mathrm{.}$

We report the first search for $\bar{\mathrm{\Lambda }}$–$\mathrm{\Lambda }$ oscillations in the decay $J\mathrm{/}\psi \to p{K}^{-}\bar{\mathrm{\Lambda }}+c\mathrm{.}c\mathrm{.}$ by analyzing $1.31\times {10}^9$ $J\mathrm{/}\psi$ events accumulated with the BESIII detector at the BEPCII collider. The $J\mathrm{/}\psi$ events are produced using $e^{+}{e}^{-}$ collisions at a center of mass energy $\sqrt{s}=3.097$~GeV. No evidence for hyperon oscillations is observed. The upper limit for the oscillation rate of $\bar{\mathrm{\Lambda }}$ to $\mathrm{\Lambda }$ hyperons is determined to be $\mathcal{P}(\mathrm{\Lambda })=\frac{\mathcal{B}(J\mathrm{/}\psi \to p{K}^{-}\mathrm{\Lambda }+c\mathrm{.}c\mathrm{.})}{\mathcal{B}(J\mathrm{/}\psi \to p{K}^{-}\bar{\mathrm{\Lambda }}+c\mathrm{.}c\mathrm{.})}<4.4\times {10}^{-6}$ corresponding to an oscillation parameter $\delta m_{\mathrm{\Lambda }\bar{\mathrm{\Lambda }}}$ of less than $3.8\times {10}^{-18}$~GeV at the 90% confidence level.