Neutron-Antineutron Oscillation Search using a 0.37 Megaton$\cdot$Year Exposure of Super-Kamiokande

Abstract

As a baryon number violating process with $\Delta B=2$, neutron-antineutron oscillation ($n\to \bar{n}$) provides a unique test of baryon number conservation. We have performed a search for $n\to \bar{n}$ oscillation with bound neutrons in Super-Kamiokande, with the full data set from its first four run periods, representing an exposure of 0.37~Mton-years. The search used a multivariate analysis trained on simulated $n\to \bar{n}$ events and atmospheric neutrino backgrounds and resulted in 11 candidate events with an expected background of 9.3 events. In the absence of statistically significant excess, we derived a lower limit on $\bar{n}$ appearance lifetime in ${}^{16}$O nuclei of $3.6\times {10}^{32}$ years and on the neutron-antineutron oscillation time of ${\tau }_{n\to \bar{n}}>4.7\times 10^8$~s at 90\% C.L..

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• Calculation of atmospheric neutrino flux using the interaction model calibrated with atmospheric muon data
• Improvement of low energy atmospheric neutrino flux calculation using the JAM nuclear interaction model
• Post--Sphaleron Baryogenesis
• Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations
• Baryon-number violation by two units and the deuteron lifetime
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Cited by in corpus (2)

• Neutron Stars with Baryon Number Violation, Probing Dark Sectors
• Affleck-Dine Baryogenesis with Observable Neutron-Anti-Neutron Oscillation