Abstract
Existing bounds on the neutron-antineutron mass mixing, epsilon _{n{bar{n}}} < mathrm{few} times 10^{-24} eV, impose a severe upper limit on n - {bar{n}} transition probability, P_{n{bar{n}}}(t) < (t/0.1 ~mathrm{s})^2 times 10^{-18} or so, where t is the neutron flight time. Here we propose a new mechanism of n- {bar{n}} transition which is not induced by direct mass mixing epsilon _{n{bar{n}}} but is mediated instead by the neutron mass mixings with the hypothetical states of mirror neutron n' and mirror antineutron {{overline{n}}} '. The latter can be as large as epsilon _{nn'}, epsilon _{nbar{n}'} sim 10^{-15} eV or so, without contradicting present experimental limits and nuclear stability bounds. The probabilities of n-n' and n-bar{n}' transitions, P_{nn'} and P_{nbar{n}'}, depend on environmental conditions in mirror sector, and they can be resonantly amplified by applying the magnetic field of the proper value. This opens up a possibility of n-{bar{n}} transition with the probability P_{n{bar{n}}} simeq P_{nn'} P_{nbar{n}'} which can reach the values sim 10^{-8} or even larger. For finding this effect in real experiments, the magnetic field should not be suppressed but properly varied. These mixings can be induced by new physics at the scale of few TeV which may also originate a new low scale co-baryogenesis mechanism between ordinary and mirror sectors.
Highlights
33 Page 2 of 11[18,19], n −n oscillation time τnn can be smaller than 1 s so that n − n mixing mass can be as large as εnn ∼ 10−15 eV, or even larger
Where n and nc = CnT are the neutron and antineutron fields, C being the charge conjugation matrix
Discovery of neutron–antineutron (n − n) oscillation [1,2,3,4] would be a clear evidence of the baryon number violation, and can shade more light on the origin of the matter– antimatter asymmetry in the Universe [5,6]
Summary
[18,19], n −n oscillation time τnn can be smaller than 1 s so that n − n mixing mass can be as large as εnn ∼ 10−15 eV, or even larger This possibility is not excluded neither by nuclear stability bounds nor by astrophysical and cosmological limits [18], and it can have observable effects for the propagation of the ultra-high energy cosmic rays at cosmological distances [20,21]. All neutral particles, elementary (as neutrinos) or composite (as the neutron) can have mixings with their mirror twins Such mixings violate lepton (L, L ) or baryon (B, B ) numbers of two sectors by one unit, and they can be originated from some relevant effective interactions in the mixed Lagrangian Lmix. 1 and 2 are a priori independent parameters which can be determined (and related to each other) in the context of UV-complete renormalizable models employing some heavy intermediate particles
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