Improved Upper Limits on Baryon-Number Violating Dinucleon Decays to Dileptons

Abstract

We consider effects of $n-\bar{n}$ oscillations and resultant matter instability due to dinucleons decays. We point out that existing upper bounds on the rates for the dinucleon decays $nn\to 2{\pi }^0$, $nn\to {\pi }^{+}{\pi }^{-}$, and $np\to {\pi }^{+}{\pi }^0$ imply upper bounds on the rates for dinucleon decays to dileptons $nn\to e^{+}{e}^{-}$, $nn\to {\mu }^{+}{\mu }^{-}$, $nn\to {\nu }_{\ell }{\bar{\nu }}_{\ell }$, and $np\to {\ell }^{+}{\nu }_{\ell }$, where $\ell =e,\mu ,\tau$. We present estimates for these upper bounds. Our bounds are substantially stronger than corresponding limits from direct searches.

Comments: 6 pages, 3 figures