Neutron oscillations for solving neutron lifetime and dark matter puzzles

Abstract

A model of n − n (neutron-mirror neutron) oscillations is proposed under the framework of the mirror matter theory with slightly broken mirror symmetry. It resolves the neutron lifetime discrepancy, i.e., the 1% difference in neutron lifetime between measurements from "beam" and "bottle" experiments. In consideration of the early universe evolution, the n − n mass difference is determined to be about 2 × 10 −6 eV/c 2 with the n − n mixing strength of about 2 × 10 −5 . The picture of how the mirror-to-ordinary matter density ratio is evolved in the early universe into the observed dark-to-baryon matter density ratio of about 5.4 is presented. Reanalysis of previous data and new experiments that can be carried out under current technology are discussed and recommended to test this proposed model. Other consequences of the model on astrophysics and possible oscillations of other neutral particles are discussed as well.Free neutrons with a lifetime of about 15 minutes are known to undergo β decay via n → p + e − +ν e due to the weak force. There has been much experimental effort over the past decades for measuring the lifetime using two different techniques. The "beam" approach is to measure the neutron flux from a cold neutron beam after it going through a region where the emitted protons are detected [1,2]. It measures directly the β decay rate as far as other hidden neutron-disappearing processes are on the level of 10 −3 or below. This approach typically gives a neutron lifetime of about 888 seconds. On the other hand, the "bottle" experiments store ultracold neutrons (UCN) confined by the gravitational force in a material or magnetic trap [3,4,5]. By measuring the neutron loss rate in the trap this method typically presents a neutron lifetime of about 880 seconds. Note that any other unknown loss processes in the trap will contribute to the measured lifetime and make it appear shorter. Another different approach using a magnetic storage ring [6] provides similar results as the "bottle" method. The 1% difference between the results of the two approaches becomes more severe recently with the most precise measurements of 887.7 ± 1.2(stat) ± 1.9(sys) s ("beam") [2] and 877.7 ± 0.7(stat) + 0.4/ − 0.2(sys) s ("bottle") [3].

Neutron’s dark secret

“…In Ref. 74 another model based on the idea of neutron-mirror neutron oscillations was proposed, but with the neutron dark decay mediated via non-perturbative effects.…”

Supersymmetric Mirror Models and Dimensional Evolution of Spacetime

“…Such a supersymmetric standard model with mirror matter extension can provide explanations for puzzles like the above-mentioned nature and masses of neutrinos and observed dark energy scale of 10 −3 eV assuming that gravitational vacuum energy is determined by a coherent sum of all scalar fields [6]. Along with predicted neutral hadron-mirror hadron oscillations, in particular, the two most important cases of n − n and K 0 − K 0 for neutrons and kaons, we can quantitatively and consistently explain many other enigmas such as neutron lifetime anomaly and dark matter [15], baryon asymmetry of the universe [18], nucleosynthesis and evolution of stars [16], ultra-high energy cosmic rays [17], and unitarity of the CKM matrix [19].…”

“…Other attempts to introduce feeble interactions between the two sectors might be going in the wrong way [12][13][14]. Latest works [6,[15][16][17][18][19][20] by keeping only the essence of mirror matter theory may indeed lead us to the new BSM physics we have all been looking for.…”

No single unification theory of everything

“…Both φ and φ present a Higgs-like dynamic mechanism by acquiring similar yet different masses (m = m ) of about 10 16 GeV. If we assume that the relative mass splitting parameter δm/m scales with temperature T and it is of order unity initially at T ∼ 10 16 GeV, then the temperature difference between the two sectors is reasonably understood and the tiny mass splitting parameter of δm/m ∼ 10 −14 [1] for later quark condensation at T ∼ 10 2 GeV is also explained.…”

“…where masses of the neutrinos are determined by the ordinary-mirror mass splitting scale of φ − φ ∼ δv with fairly well constrained relative scale of δv/v = 10 −15 -10 −14 [1][2][3][4][5][6].…”