Fast neutron–mirror neutron oscillation and ultra high energy cosmic rays

Berezhiani, Zurab; Bento, Luís

doi:10.1016/j.physletb.2006.03.008

Cited by 82 publications

(71 citation statements)

References 53 publications

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“…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.…”

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confidence: 95%

“…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].…”

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confidence: 99%

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Direct Experimental Limit on Neutron–Mirror-Neutron Oscillations

et al. 2007

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In case a mirror world with a copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, the mirror neutron n ′ , could potentially mix and undergo nn ′ oscillations. The interaction of an ordinary magnetic field with the ordinary neutron would lift the degeneracy between the mirror partners, diminish the n ′ -amplitude in the n-wavefunction and, thus, suppress its observability. We report an experimental comparison of ultracold neutron storage in a trap with and without superimposed magnetic field. No influence of the magnetic field is found and, assuming negligible mirror magnetic fields, a limit on the oscillation time τ nn ′ > 103 s (95% C.L.) is derived.PACS numbers: 11.30. Er, 11.30.Fs, 14.20.Dh, The concept of a mirror world, as an attempt to restore global parity symmetry, has attracted interest since the 1950's, started by the famous paper of Lee and Yang [1] and significantly expanded in the work of Kobzarev, Okun, and Pomeranchuk [2]. The mirror matter idea was first applied to the Standard Model of particle physics in [3]. More recent overviews can be found in [4,5]. The mirror world could hold a copy of the particle spectrum of our ordinary world. Matter and mirror matter would interact via gravity and present a viable explanation to the dark matter problem [6,7,8,9,10]. 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]. 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].Possible approaches to nn ′ oscillation experiments with sensitivities of several hundred seconds have been discussed in [19]. One approach is to search for nn ′ oscillations by comparing the storage of ultracold neutrons (UCN) in vacuum in a trap in the presence and the absence, respectively, of a magnetic field. The essential idea is that the neutron and mirror neutron states would be degenerate in the absence of a magnetic field and nn ′ transitions could occur. (The absence of mirror magnetic fields at the location of the experiment is assumed throughout this paper [20].) The interaction of the neutron with a magnetic field would lift the degeneracy and suppress the transition into a mirror neutron which, of course, does not interact with the ordinary magnetic field, nor with the trap via the ordinary strong interaction. Thus...

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Direct Experimental Limit on Neutron–Mirror-Neutron Oscillations

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“…3 Probably, the most similar mechanism of the one proposed here is in [39][40][41]43]. In this case Baryon number is violated by a baryonic 'RH neutron', with a B-violating Majorana mass term.…”

Section: A Model For a Neutron Majorana Massmentioning

confidence: 63%

‘Exotic vector-like pair’ of color-triplet scalars

Addazi

2015

J. High Energ. Phys.

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We propose a minimal extension of Standard Model, generating a Majorana mass for neutron, connected with a mechanism of Post-Sphaleron Baryogenesis. We consider an 'exotic vector-like pair' of color-triplet scalars, an extra Majorana fermion ψ, and a scalar field φ, giving mass to ψ. The vector-like pair is defined 'exotic' because of a peculiar mass term of the color-triplet scalars, violating Baryon number as ∆B = 1. Such a mass term could be generated by exotic instantons in a class of string-inspired completions of the Standard Model: open (un-)oriented strings attached between D-brane stacks and Euclidean D-branes. A Post-Sphaleron Baryogenesis is realized through φ-decays into six quarks (antiquarks), or through ψ-decays into three quarks (antiquarks). This model suggests some intriguing B-violating signatures, testable in the next future, in NeutronAntineutron physics and LHC. We also discuss limits from FCNC. Sterile fermion can also be light as 1 − 100 GeV. In this case, the sterile fermion could be (meta)-stable and n −n oscillation can be indirectly generated by two n − ψ, ψ −n oscillations, without needing of an effective Majorana mass for neutron. Majorana fermion ψ can be a good candidate for WIMP-like dark matter.

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“…7 These considerations are briefly summarized, in a footnote, in the paper [48,49]. 8 Another possibility for neutrino mass generation is within large extra dimension scenari [54], that mutatis mutandis could work also for neutrons.…”

Section: Jhep12(2014)089mentioning

confidence: 99%

“…In fact, in general, this matrix can violate CP, because of the Yukawa-like couplings inside 12 These limits are placed in the search for a hint of Mirror Dark Matter. The phenomenology of neutronmirror neutron oscillations are considered in [106][107][108][109]. Currently, there is an anomaly of 5σ (with respect to the null hypothesis) in condition of magnetic field B 0.2 Gauss in Ultra Cold Neutron (UCN) [105].…”

Section: Jhep12(2014)089mentioning

confidence: 99%

Neutron Majorana mass from exotic instantons

Addazi

Bianchi

2014

J. High Energ. Phys.

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We show how a Majorana mass for the neutron could result from nonperturbative quantum gravity effects peculiar to string theory. In particular, "exotic instantons" in un-oriented string compactifications with D-branes extending the (supersymmetric) standard model could indirectly produce an effective operator δm n t n + h.c.. In a specific model with an extra vector-like pair of 'quarks', acquiring a large mass proportional to the string mass scale (exponentially suppressed by a function of the string moduli fields), δm can turn out to be as low as 10 −24 -10 −25 eV.The induced neutron-antineutron oscillations could take place with a time scale τ nn > 10 8 s that could be tested by the next generation of experiments. On the other hand, proton decay and FCNC's are automatically strongly suppressed and are compatible with the current experimental limits.Depending on the number of brane intersections, the model may also lead to the generation of Majorana masses for R-handed neutrini. Our proposal could also suggest neutron-neutralino or neutron-axino oscillations, with implications in UCN, Dark Matter Direct Detection, UHECR and Neutron-Antineutron oscillations.This suggests to improve the limits on neutron-antineutron oscillations, as a possible test of string theory and quantum gravity.

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Fast neutron–mirror neutron oscillation and ultra high energy cosmic rays

Cited by 82 publications

References 53 publications

Direct Experimental Limit on Neutron–Mirror-Neutron Oscillations

Direct Experimental Limit on Neutron–Mirror-Neutron Oscillations

‘Exotic vector-like pair’ of color-triplet scalars

Neutron Majorana mass from exotic instantons

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