Search for neutron-antineutron oscillation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>16</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>nuclei

Takita, M.; Arisaka, K.; Kajita, T.; Kifune, T.; Koshiba, M.; Miyano, K.; Nakahata, M.; Oyama, Y.; Sato, Nobuaki; Suda, T.; Suzuki, A.; Takahashi, K.; Totsuka, Y.

doi:10.1103/physrevd.34.902

Cited by 78 publications

(78 citation statements)

References 20 publications

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“…The major sources of errors in the detection efficiency are the results of uncertainties in the models for propagation of pions and omega mesons through the residual nucleus. In particular, the error due to uncertainties in the π-nucleon cross section is 20.0%, as estimated from the π- 16 O scattering data shown in [13] and by comparing results from two independent nuclear interaction programs originally developed by IMB [13] and by Kamiokande [14] (6.1%). The uncertainty from the (n + nucleon) annihilation branching ratios is estimated to be 4.6% by comparing different MC results based on variations in the assumed branching ratios [28,29].…”

Section: Systematic Errorsmentioning

confidence: 99%

“…The previous best 90 % confidence level (C.L.) lifetime limits for bound neutrons are from IMB with 1.7 and 2.4 ×10 31 year [13] in two different analyses, Kamiokande with 4.3 × 10 31 year in oxygen [14], Soudan 2 with 7.2 × 10 31 year in iron [15], and Frejus with 6.5 × 10 31 year in iron [16]. The current best limit on the oscillation time of unbound neutrons is given by ILL (Grenoble) as 0.86 × 10 8 seconds [17].…”

Section: Introductionmentioning

confidence: 99%

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Search forn−n¯oscillation in Super-Kamiokande

Abe¹,

Hayato²,

Iida³

et al. 2015

Phys. Rev. D

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136

177

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2A search for neutron-antineutron (n −n) oscillation was undertaken in Super-Kamiokande using the 1,489 day livetime or 2.45 × 10 34 neutron-year exposure data. This process violates both baryon and (baryon−lepton) numbers by two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the universe. No evidence for n −n oscillation was found, the lower limit of the lifetime for neutrons bound in 16 O, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9 × 10 32 years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7 × 10 8 s using a theoretical value of the nuclear suppression factor of 0.517 × 10 23 s −1 and its uncertainty.

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Section: Systematic Errorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Search forn−n¯oscillation in Super-Kamiokande

Abe¹,

Hayato²,

Iida³

et al. 2015

Phys. Rev. D

Self Cite

136

177

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“…Secondly, if we choose the strange quark component in the nucleon to be about 1%, then choosing λ 1 λ ′ 12 ≃ 10 −4 , we find that G ∆B=2 ≃ 10 −27 GeV −5 which corresponds to the present limit on τ N −N ∼ 10 8 sec. [3,4].…”

Section: Neutron-anti-neutron Oscillationmentioning

confidence: 99%

Unified TeV Scale Picture of Baryogenesis and Dark Matter

2007

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We present a simple extension of MSSM which provides a unified picture of cosmological baryon asymmetry and dark matter. Our model introduces a gauge singlet field N and a color triplet field X which couple to the right-handed quark fields. The out-of equilibrium decay of the Majorana fermion N mediated by the exchange of the scalar field X generates adequate baryon asymmetry for M N ∼ 100 GeV and M X ∼ TeV. The scalar partner of N (denotedÑ 1 ) is naturally the lightest SUSY particle as it has no gauge interactions and plays the role of dark matter.Ñ 1 annihilates into quarks efficiently in the early universe via the exchange of the fermionicX field. The model is experimentally testable in (i) neutron-antineutron oscillations with a transition time estimated to be around 10 10 sec, (ii) discovery of colored particles X at LHC with mass of order TeV, and (iii) direct dark matter detection with a predicted cross section in the observable range. ‡

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“…caused by this process (leading to multipion final states) of τ m.i. > ∼ 0.6 × 10 32 yrs which, with reasonable inputs for the nuclear potentials V n and Vn, have yielded a current limit very close to that from searches with free n's: τ nn ≥ 1.2 × 10 8 sec, i.e., |δm| ≤ 0.6 × 10 −32 GeV [25]. In 4D, H ef f consists of a sum of six-quark operators O i with coefficients c i having (mass) dimension −5.…”

mentioning

confidence: 99%

“…Requiring that the resultant value of |δm| be less than the experimental limit, 1/(1.2 × 10 8 sec) = 0.55 × 10 −32 GeV [24,25], we obtain the bound The uncertainty in the calculation of the matrix element n|O 4 |n is relatively unimportant for our bound because of the 1/9 power in (13) [26].…”

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confidence: 99%

n-n¯Oscillations in Models with Large Extra Dimensions

2002

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We analyze n−n oscillations in generic models with large extra dimensions in which standard-model fields propagate and fermion wavefunctions have strong localization. We find that in these models n −n oscillations might occur at levels not too far below the current limit.11.10. Kk,11.30.Fs,14.20.Dh Although current experimental data are fully consistent with a four-dimensional Minkowski spacetime, it is useful to explore the possibility of extra dimensions, both from a purely phenomenological point of view and because the main candidate theory for quantum gravity -string theory -suggests the existence of higher dimensions. Here we shall focus on theories in which the standard-model (SM) fields can propagate in the extra dimensions and the wavefunctions of the SM fermions have strong localization (with Gaussian profiles) at various points in this extra-dimensional space [1]- [9]. Such models are of interest partly because they can provide a mechanism for obtaining a hierarchy in fermion masses and quark mixing. In generic models of this type, excessively rapid proton decay can be avoided by arranging that the wavefunction centers of the u and d quarks are separated far from those of the e and µ [1]. However, this separation does not, by itself, guarantee adequate suppression of another source of baryon number violation, namely n −n oscillations. Here we shall analyze these oscillations in generic models of this type. Early studies of n −n oscillations in conventional d = 4 dimensional spacetime include [10]-[16]; there is currently renewed experimental and theoretical interest [17,18].Our theoretical framework is as follows. Usual spacetime coordinates are denoted as x ν , ν = 0, 1, 2, 3 and the n extra coordinates as y λ ; for definiteness, the latter are taken to be compact. The framework is such that fermion fields have the form Ψ(x, y) = ψ(x)χ(y). In the extra dimensions the SM fields are assumed tofields thus have Kaluza-Klein (KK) mode decompositions. We shall work in a low-energy effective field theory approach with an ultraviolet cutoff M * . These models provide a possible explanation for the hierarchy in the fermion mass matrices via the localization of fermion wavefunctions with half-width µ −1 << L at various points in the higherdimensional space. We denote ξ = µL; ξ ∼ 30 is chosen for adequate separation of the various fermion wavefunctions while still fitting well within the thick brane. As a result of this localization, the y-dependent part of the wavefunction for a fermion field f has the generic form χ f (y) = Ae 1/2 . For ℓ = 1 and ℓ = 2, this fermion localization can be accomplished in a low-energy fieldtheoretic manner by coupling to a scalar with a kink or vortex solution, respectively [19]. The normalization factor A = (2/π) ℓ/4 µ ℓ/2 is included so that after the integration over the ℓ extra dimensions, the kinetic termψ(x)i∂ /ψ(x) has canonical normalization. Starting from an effective Lagrangian in the d-dimensional spacetime, one obtains the resultant effective theory in four dimensio...

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Search for neutron-antineutron oscillation inO16nuclei

Cited by 78 publications

References 20 publications

Search forn−n¯oscillation in Super-Kamiokande

Search forn−n¯oscillation in Super-Kamiokande

Unified TeV Scale Picture of Baryogenesis and Dark Matter

n-n¯Oscillations in Models with Large Extra Dimensions

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