New experimental limits on neutron – mirror neutron oscillations in the presence of mirror magnetic field

Z. Berezhiani; R. Biondi; P. Geltenbort; I. A. Krasnoshchekova; V. E. Varlamov; A. V. Vassiljev; O. M. Zherebtsov

doi:10.1140/epjc/s10052-018-6189-y

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2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2018) 78: 717
https://doi.org/10.1140/epjc/s10052-018-6189-y

Regular Article - Experimental Physics

New experimental limits on neutron – mirror neutron oscillations in the presence of mirror magnetic field

Z. Berezhiani¹^,2^*, R. Biondi¹^,2, P. Geltenbort³, I. A. Krasnoshchekova⁴, V. E. Varlamov⁴, A. V. Vassiljev⁴ and O. M. Zherebtsov⁴

¹ Dipartimento di Fisica e Chimica, Università di L’Aquila, 67100, Coppito, L’Aquila, Italy
² INFN, Laboratori Nazionali del Gran Sasso, 67010, Assergi, L’Aquila, Italy
³ Institut Laue–Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
⁴ B. P. Konstantinov Petersburg Nuclear Physics Institute of National Research Centre ‘Kurchatov Institute’, 188300, Gatchina, Leningrad Region, Russia

^* e-mail: berezhiani@lngs.infn.it

Received: 23 March 2018
Accepted: 19 August 2018
Published online: 5 September 2018

Abstract

Present experimental and astrophysical limits do not exclude that the neutron (n) oscillation into mirror neutron ( $$n'$$ ), a sterile state exactly degenerate in mass with the neutron, can be a very fast process, in fact faster than the neutron decay itself, in which case it would have very interesting implications in cosmology and astrophysics. This process is sensitive to the magnetic field. Namely, if the mirror magnetic field $\mathbf {B}'$ exists at the Earth, $$n{-}n'$$ oscillation probability can be suppressed or resonantly amplified by the applied magnetic field $\mathbf {B}$ , depending on its strength and on the angle $\beta$ between $\mathbf {B}$ and $\mathbf {B}'$ . We present the results of ultra-cold neutron storage measurements aiming to check the anomalies observed in previous experiments which could be a signal for $$n{-}n'$$ oscillation in the presence of mirror magnetic field $B'\sim 0.1$ G. From the analysis of the experimental data new lower limits on oscillation time as a function of $$B'$$ were obtained, assuming that the mirror magnetic field is constant in time: $\tau _{nn'} > 17$ s (95 % C.L.) for any $$B'$$ between 0.08 and 0.17 G, and $\tau _{nn'}/\sqrt{\cos \beta } > 27$ s (95 % C.L.) for any $$B'$$ in the interval ( $0.06\div 0.25$ ) G.