The Final Frontier for Proton Decay

arXiv (Cornell University)

Abstract

We present a novel experimental concept to search for proton decay. Using paleo-detectors, ancient minerals acquired from deep underground which can hold traces of charged particles, it may be possible to conduct a search for $p \to \barν K^+$ via the track produced at the endpoint of the kaon. Such a search is not possible on Earth due to large atmospheric-neutrino-induced backgrounds. However, the Moon offers a reprieve from this background, since the conventional component of the cosmic-ray-induced neutrino flux at the Moon is significantly suppressed due to the Moon's lack of atmosphere. For a 100 g, $10^9$ year old (100 kton$\cdot$year exposure) sample of olivine extracted from the Moon, we expect about 0.5 kaon endpoints due to neutrino backgrounds, including secondary interactions. If such a lunar paleo-detector sample can be acquired and efficiently analyzed, proton decay sensitivity exceeding $τ_p\sim10^{34}$ years may be achieved, competitive with Super-Kamiokande's current published limit ($τ_p>5.9\times 10^{33}$ years at 90% CL) and the projected reach of DUNE and Hyper-Kamiokande in the $p \to \barν K^+$ channel. This concept is clearly futuristic, not least since it relies on extracting mineral samples from a few kilometers below the surface of the Moon and then efficiently scanning them for kaon endpoint induced crystal defects with sub-micron-scale resolution. However, the search for proton decay is in urgent need of a paradigm shift, and paleo-detectors could provide a promising alternative to conventional experiments.

Authors 5

1. Sebastian Baum Aachen Institute for Theoretical Particle Physics and Cosmology

   RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Particle Physics and Cosmology , RWTH Aachen University , D-52056 Aachen , Germany

2. Cassandra Little

   University of Michigan

   Affiliation as printed

   University of Michigan , Ann Arbor , Michigan 48109 , USA

3. Paola R. SALA

   Istituto Nazionale di Fisica Nucleare, Sezione di Milano

   Affiliation as printed

   INFN Milano , via Celoria 16 , I-20133 Milano , Italy

4. J. Spitz

   University of Michigan

   Affiliation as printed

   University of Michigan , Ann Arbor , Michigan 48109 , USA

5. Patrick Stengel

   Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara

   Affiliation as printed

   INFN Ferrara , via Giuseppe Saragat 1 , I-44122 Ferrara , Italy