Search for Λ¯−Λ Baryon-Number-Violating Oscillations in the Decay J/ψ→pK−Λ¯+c.c.

Le résumé fourni par la source

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

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