Possibility Of First-order Phase Transition Research Articles

Gravitational waves from a scotogenic two-loop neutrino mass model

We propose a framework to account for neutrino masses at the two-loop level. This mechanism introduces new scalars and Majorana fermions to the Standard Model. It assumes the existence of a global U(1)×Z2 symmetry which after partial breaking provides the stability of the dark matter candidates of the theory. The rich structure of the potential allows for the possibility of first-order phase transitions (FOPTs) in the early Universe which can lead to the generation of primordial gravitational waves. Taking into account relevant constraints from lepton flavor violation, neutrino physics, as well as the trilinear Higgs couplings at next-to-leading order accuracy, we have found a wide range of possible FOPTs which are strong enough to be probed at the proposed gravitational-wave interferometer experiments such as LISA. Published by the American Physical Society 2024

Phases of the Bose–Einstein Condensate Dark Matter Model with Both Two- and Three-Particle Interactions

In this paper, we further elaborate on the Bose–Einstein condensate (BEC) dark matter model extended in our previous work [Phys. Rev. D 2020, 102, 083510] by the inclusion of sixth-order (or three-particle) repulsive self-interaction term. Herein, our goal is to complete the picture through adding to the model the fourth-order repulsive self-interaction. The results of our analysis confirm the following: while in the previous work the two-phase structure and the possibility of first-order phase transition was established, here we demonstrate that with the two self-interactions involved, the nontrivial phase structure of the enriched model remains intact. For this to hold, we study the conditions which the parameters of the model, including the interaction parameters, should satisfy. As a by-product and in order to provide some illustration, we obtain the rotation curves and the (bipartite) entanglement entropy for the case of a particular dwarf galaxy.

Theoretical Possibility of First-Order Phase Transition in Disordered Spin-Peierls Systems

Impurity effects on spin-Peierls (SP) systems are investigated by using the phase Hamiltonian including mean field interchain interactions at T =0. It is shown that impurities induce antiferromagne...

Hartree-Fock theory of Skyrmions in quantum Hall ferromagnets

We report on a study of the charged-Skyrmion or spin-texture excitations which occur in quantum Hall ferromagnets near odd Landau-level filling factors. Particle-hole symmetry is used to relate the spin-quantum numbers of charged particle and hole excitations and neutral particle-hole pair excitations. Hartree-Fock theory is used to provide quantitative estimates of the energies of these excitations and their dependence on Zeeman coupling strength, Landau-level quantum numbers, and the thicknesses of the two-dimensional electron layers. For the case of \ensuremath{\nu} near three we suggest the possibility of first-order phase transitions with increasing Zeeman coupling strength from a many-Skyrmion state to one with many maximally spin-polarized quasiparticles.

Critical phenomena in constrained systems and random-field problem

Using a theory of critical phenomena in constrained systems, we find that for the critical exponents of the experimental randomfield Ising model, Fisher renormalization holds place. Considerations about the sign of the specific-heat exponent and the possibility of first-order phase transition are made.

On the possibility of first-order transitions in Ising systems of triplet ions with zero-field splitting II

An Ising system consisting of triplet ions with a zero-field splitting D and an exchange interaction J between nearest neighbours has been investigated using a molecular field approximation. The behaviour of the susceptibility is discussed. The possibility of first-order phase transitions in magnetic fields is investigated in the case of ferromagnetic exchange ( J > 0). In the limit H → ∞, D → ∞, μH − D = = finite, the system is equivalent to an Ising system of doublet ions with an appropriate value of the exchange interaction in a magnetic field. For large values of D and sufficiently low temperatures, a magnetic field can give rise to one first-order transition, if J > 0, and to two second-order transitions, if J < 0.

On the possibility of first-order phase transitions in Ising systems of triplet ions with zero-field splitting

An Ising system consisting of triplet ions ( S=1) with zero-field splitting and exchange interaction between nearest neighbours has been investigated using a molecular field approximation. The triplets are split into a singlet and a doublet by a crystal field with a n-fold rotation axis ( n>2). In the absence of a magnetic field no magnetic ordering occurs for D > 1 2 zJ , where D is the zero-field splitting, i.e. the separation between singlet and doublet, J is the exchange parameter and z is the number of nearest neighbours. For D < 1 3 zJ ln 4 there is a second-order phase transition. The Curie temperature decreases from k -1 zJ to (3 k) -1 zJ, if D increases from -∞ to 1 3 zJ ln 4. For 1 3 zJ ln 4 < D < 1 2 zJ there is a first-order phase transition. At the transition temperature T c the relative magnetization 〈 S z〉 jumps discontinuously from the value 0 to a finite value S c . If D increases from 1 3 zJ ln 4 to 1 2 zJ, T c decreases from (3 k) -1 to 0 and S c increases from 0 to 1.