Neutron–Mirror-Neutron Oscillations: How Fast Might They Be?

Abstract

We discuss implications of open string theory in B-violating low energy physics. In particular, exotic instantons can dynamically generate effective the six quark operator, leading to a neutron-antineutron transition. The proton is not destabilized and flavor changing neutral currents are under control.

Direct Experimental Limit on Neutron–Mirror-Neutron Oscillations

“…The result impacts the role nn ′ oscillations can play in the transport of ultra-high energy cosmic rays over large distances [12,15], although, it may not completely rule out the nn ′ -explanation for events above the GZK cutoff.…”

“…An indirect limit of the order τ nn ′ ≥ 1 s has been derived in [12] based on the search for neutron -antineutron (nn) oscillations [14]. Fast nn ′ oscillations with τ nn ′ ∼ 1 s, or at least much shorter than the neutron β-decay lifetime, could explain [12,15] the origin of ultra-high energy cosmic rays above the Greisen-Zatsepin-Kuzmin (GZK) cutoff [16,17]. The viability of models and implications have been further discussed in [18].…”

“…Recently it was pointed out [12] that no direct experimental limits exist on the oscillation time τ nn ′ [13] between ordinary matter neutrons (n) and the speculative mirror neutrons (n ′ ). An indirect limit of the order τ nn ′ ≥ 1 s has been derived in [12] based on the search for neutron -antineutron (nn) oscillations [14]. Fast nn ′ oscillations with τ nn ′ ∼ 1 s, or at least much shorter than the neutron β-decay lifetime, could explain [12,15] the origin of ultra-high energy cosmic rays above the Greisen-Zatsepin-Kuzmin (GZK) cutoff [16,17].…”

“…Besides gravity, other (new) interactions could show up in minute mixings of neutral matter particles -such as neutrinos, pions, kaons, or positronium (see [11] for e + e − ) -and their degenerate mirror partners making oscillations between them possible. Recently it was pointed out [12] that no direct experimental limits exist on the oscillation time τ nn ′ [13] between ordinary matter neutrons (n) and the speculative mirror neutrons (n ′ ). An indirect limit of the order τ nn ′ ≥ 1 s has been derived in [12] based on the search for neutron -antineutron (nn) oscillations [14].…”

Shadow dark matter, sterile neutrinos and neutrino events at IceCube

“…3 The shadow neutrinos may have mixing with ordinary ones [4]. We assume that operators mixing ν e,µ,τ and ν e,µ,τ states respect a conservation of a combined lepton numberL = L − L [10], and that all operators for neutrino masses are suppressed by the Planck scale M Pl [5]. Hence, for neutrino masses and mixing we consider the following operators (family indices are suppressed):…”