Neutron-mirror neutron mixing and neutron stars

Abstract

The oscillation of neutron n into mirror neutron $$n'$$ n ′ , its mass degenerate partner from dark mirror sector, can gradually transform the neutron stars into the mixed stars consisting in part of mirror dark matter. In quark stars $$n-n'$$ n - n ′ transitions are suppressed. We study the structure of mixed stars and derive the mass-radius scaling relations between the configurations of purely neutron star and maximally mixed star (MMS) containing equal amounts of ordinary and mirror components. In particular, we show that the MMS masses can be at most $$M^{\mathrm{max}}_{NS}/\sqrt{2}$$ M NS max / 2 , where $$M^\mathrm{max}_{NS}$$ M NS max is a maximum mass of a pure neutron star allowed by a given equation of state. We evaluate $$n-n'$$ n - n ′ transition rate in neutron stars, and show that various astrophysical limits on pulsar properties exclude the transition times in a wide range $$10^{5}\,\text {year}< \tau _\varepsilon < 10^{15}\,\text {year}$$ 10 5 year < τ ε < 10 15 year . For short transition times, $$\tau _\varepsilon < 10^5$$ τ ε < 10 5 year, the different mixed stars of the same mass can have different radii, depending on their age, which possibility can be tested by the NICER measurements. We also discuss subtleties related with the possible existence of mixed quark stars, and possible implications for the gravitational waves from the neutron star mergers and associated electromagnetic signals.

Dark Matter interpretation of the neutron decay anomaly

“…Third, the precise SM prediction of the neutron decay rate, possibly Γ SM n = 1/(878.7± 0.6) s [20,21], agrees with the bottle experiments disfavouring new physics contributions that increase the neutron decay rate. This might indicate that the neutron decay anomaly could just be due to some under-estimated systematic uncertainty of 'beam' experiments, or that it needs alternative interpretations where the neutron oscillates (with a resonant enhancement thanks to magnetic fields in the apparata) into a composite twin of the neutron [21][22][23]. 1 However, the quoted precise SM prediction for Γ SM n employs determinations of V ud and measurements of the neutron axial coupling constant g A that are potentially problematic at the claimed level of precision.…”

A Search for Neutron to Mirror Neutron Oscillation Using Neutron Electric Dipole Moment Measurements

“…Neutron to mirror-neutron oscillation is one such process [42]. Neutron to mirror-neutron oscillations could provide a mechanism to relax the Greisen-Zatsepin-Kuzmin (GZK) limit [43,44], have implications upon neutrons from solar flares [45], and affect neutron stars [46,47]. Neutron to mirror-neutron oscillations have also been discussed in the context of neutron to anti-neutron oscillation [42,[48][49][50][51][52].…”

Neutron-Mirror Neutron Oscillations in Absorbing Matter

“…In fact, both n − n and n − n mixing phenomena could be originated from the same theoretical framework [21,25]). This could also have interesting astrophysical implications, e.g., for extreme energy cosmic rays [26,27], for solar neutrons [28], and for neutron stars [29][30][31].…”