arXiv subjects

Itay Hen

Publications and source records attributed to Itay Hen.

79 records · Page 5Linked to original sources

arXiv2009

Superfluid to Mott-insulator transition of hardcore bosons in a superlattice

We study the superfluid to Mott-insulator (SF-MI) transition of hardcore bosons in commensurate superlattices in two and three dimensions. We focus on the special case where the superlattice has period two and the system is at half filling. We obtain exact numerical results by using the stochastic series expansion (SSE) algorithm, and compute various properties of the system, such as the ground-state energy, the fraction of bosons in the zero-momentum mode, the superfluid density, and the compressibility. With finite-size scaling, we find the critical points of the phase transition. We also explore the extent to which several approximate solutions such as mean-field theory, with and without spin-wave corrections, can help one gain analytical insight into the behavior of the system in the vicinity of the phase transition.

cond-mat.stat-mech↗

arXiv2009

Review of Rotational Symmetry Breaking in Baby Skyrme Models

We discuss one of the most interesting phenomena exhibited by baby skyrmions -- breaking of rotational symmetry. The topics we will deal with here include the appearance of rotational symmetry breaking in the static solutions of baby Skyrme models, both in flat as well as in curved spaces, the zero-temperature crystalline structure of baby skyrmions, and finally, the appearance of spontaneous breaking of rotational symmetry in rotating baby skyrmions.

hep-th↗

arXiv2008

Equation of Motion for the Quantum Characteristic Functions

In this paper, we derive equations of motion for the normal-order, the symmetric-order and the antinormal-order quantum characteristic functions, applicable for general Hamiltonian systems. We do this by utilizing the `characteristic form' of both quantum states and Hamiltonians. The equations of motion we derive here are rather simple in form and in essence, and as such have a number of attractive features. As we shall see, our approach enables the descriptions of quantum and classical time evolutions in one unified language. It allows for a direct comparison between quantum and classical dynamics, providing insight into the relations between quantum and classical behavior, while also revealing a smooth transition between quantum and classical time evolutions. In particular, the $\hbar\to 0$ limit of the quantum equations of motion instantly recovers their classical counterpart. We also argue that the derived equations may prove to be very useful in numerical simulations.

quant-ph↗

arXiv2008

Spontaneous Breaking of Rotational Symmetry in Rotating Solitons - a Toy Model of Excited Nucleons with High Angular Momentum

We study the phenomenon of spontaneous breaking of rotational symmetry (SBRS) in the rotating solutions of two types of baby Skyrme models. In the first the domain is a two-sphere and in the other, the Skyrmions are confined to the interior of a unit disk. Numerical full-field results show that when the angular momentum of the Skyrmions increases above a certain critical value, the rotational symmetry of the solutions is broken and the minimal energy configurations become less symmetric. We propose a possible mechanism as to why SBRS is present in the rotating solutions of these models, while it is not observed in the `usual' baby Skyrme model. Our results might be relevant for a qualitative understanding of the non-spherical deformation of excited nucleons with high orbital angular momentum.

hep-ph↗

arXiv2008

Hexagonal Structure of Baby Skyrmion Lattices

We study the zero-temperature crystalline structure of baby Skyrmions by applying a full-field numerical minimization algorithm to baby Skyrmions placed inside different parallelogramic unit-cells and imposing periodic boundary conditions. We find that within this setup, the minimal energy is obtained for the hexagonal lattice, and that in the resulting configuration the Skyrmion splits into quarter-Skyrmions. In particular, we find that the energy in the hexagonal case is lower than the one obtained on the well-studied rectangular lattice, in which splitting into half-Skyrmions is observed.

hep-th↗

arXiv2007

Baby Skyrmions on the Two-Sphere

We find the static multi-soliton solutions of the baby Skyrme model on the two-sphere for topological charges 1 =< B =< 14. Numerical full-field results show that the charge-one Skyrmion is spherical, the charge-two Skyrmion is toroidal, and Skyrmions with higher charge all have point symmetries which are subgroups of O(3). We find that a rational map ansatz yields very good approximations to the full-field solutions. We point out a strong connection between the discrete symmetries of our solutions and those of corresponding solutions of the 3D Skyrme model.

hep-th↗

arXiv2007

Rotational symmetry breaking in baby Skyrme models

We consider multisolitons with charges 1 =< B =< 5 in the baby Skyrme model for the one-parametric family of potentials U=μ^2 (1-ϕ_3)^s with 0<s =< 4. This class of potentials is a generalization of the `old' (s=1) and `holomorphic' (s=4) baby Skyrme models. We find that for charge one, stable solutions exist for every value of s and they are rotationally-symmetric. For higher charges, stable solutions exist only below s \approx 2. In the charge-two sector the stable solutions are always rotationally-symmetric and ring-like. For charge three and above, rotational symmetry is exhibited only in the small s region; above a certain critical value of s, this symmetry is broken and a strong repulsion between the constituent one-Skyrmions becomes apparent. We also compute the spatial energy distributions of these solutions.

hep-th↗