Search of Trineutron and Tetraneutron

Abstract

In light of a new experiment which claims an identification of tetraneutron [3], we discuss the results of experimental search of trineutron and tetraneutron in different nuclear reactions. A summary of theoretical studies for trineutron and tetraneutron within variety of approaches such as variational methods, the method of Faddeev and Faddeev-Yakubovsky equations, and the method of hyperspherical harmonics are presented.The cataclysmic events that occur near the end of the life of a star lead to one of only three possible final states: a white dwarf, a neutron star, or a black hole. The mass of the star, particularly that of the core, appears to be the primary factor in determining the final state. A more massive star would need to be hotter to balance its stronger gravitational attraction. While a star is burning, the heat in the star pushes out and balances the force of gravity. When the star's fuel is spent, and it stops burning, there is no heat left to counteract the force of gravity. How much mass the star had when it died determines what it becomes. Detailed calculations have shown that for star with mass less than about 1.4 times the mass of our sun electron degeneracy pressure permanently halts collapse. White dwarfs are stable cold stars that are supported by electron degeneracy pressure. Calculations show that stars that have between 1.4 and 3 times the mass of the sun implode into neutron stars that are the end product of stellar evolution, and their outer core is composed of neutrons at truly enormous densities. The central region of the neutron star is supported by the degeneracy pressure of neutrons. A star with mass greater than 3 times than of the sun gets crushed into a single point -a black hole.At high density, when the sum of masses of a proton and electron, and Fermi energy over c 2 exceeds the neutron mass, it is energetically favorable to combine a proton and an electron into a neutron: p + e − → n + ν e . Both neutron and neutrino rich matter are produced at the core. Since the mean free path of neutrinos is much smaller than the radius of neutron stars neutrinos do not accumulate inside neutron stars. Therefore, at higher densities, matter becomes more and more neutron-rich. A progressive neutronization of matter at higher and higher densities makes a lower energy state. An attractive pairing interaction between neutrons, can couple them to form a state with integer spin and, therefore, paired neutrons act like bosons. These "bosons" can form a condensate-like state in which all of the bosons occupy the same quantum state and form a superfluid. Just as the pairing of protons that are charged fermions forms a superconductor. In that same general sense, we also can have superconductivity and superfluidity in neutron stars. Thus, we can have superconductivity and superfluidity in the outer core of neutron stars. Superconductivity and superfluidity, if observed in neutron stars, could tell us a lot about the pairing and hence inform us about aspects of nuclear physics that are mighty diffi...

Unnuclear physics

“…Nuclear reactions involving three and four neutrons in the final states have been investigated in the searches for bound trineutron and tetraneutrons or narrow resonances (see, e.g., Ref. [25][26][27]). Our prediction is made under the assumption that there is no narrow resonance with energy comparable or less than the kinetic energy of the neutrons in the frame of their center of mass.…”

Three-body resonances in pionless effective field theory

“…In the case of the three-neutron system, we suppress the isospin quantum number 3/2, while the three-body force is absent because the Pauli principle precludes a momentum-independent contact three-neutron force. 2 To leading order in pionless EFT, only S-wave two-body interactions contribute. We consider the basis states…”

“…The search for few-neutron resonances and bound states has a long history with ambiguous results [1,2]. In this work we focus on the topic of three-neutron resonances, motivated by a controversial discussion of this topic in the recent literature [3][4][5][6][7][8][9][10].…”