On the relation between boundary proposals and hidden symmetries of the extended pre-big bang quantum cosmology

A framework associating quantum cosmological boundary conditions to minisuperspace hidden symmetries has been introduced in \cite{7}. The scope of the application was, notwithstanding the novelty, restrictive because it lacked a discussion involving realistic matter fields. Therefore, in the herein letter, we extend the framework scope to encompass elements from a scalar-tensor theory in the presence of a cosmological constant. More precisely, it is shown that hidden minisuperspace symmetries present in a pre-big bang model suggest a process from which boundary conditions can be selected.Comment: 15 pages, no figures, to appear in European Physical Journal

On the Schur multipliers of Lie superalgebras of maximal class

Let $L$ be a non-abelian nilpotent Lie superalgebra of dimensiom $(m|n)$. Nayak shows there is a non-negative $s(L)$ such that $s(L)=\frac{1}{2}(m+n-2)(m+n-1)+n+1-\dim{\mathcal{M}(L)}$. Here we intend that classify all non-abelian nilpotent Lie superalgebras, when $1\leq s(L)\leq 10$. Moreover, we classify the structure of all Lie superalgebras of dimension at most $5$ such that $\dim {L^2}=\dim {\mathcal{M}(L)}$

Subgroup Theorems for the B0~\tilde{B_0}-invariant of groups

U. Jezernik and P. Moravec have shown that if $G$ is a finite group with a subgroup $H$ of index $n$, then nth power of the Bogomolov multiplier of $G$, $\tilde{B_0}(G)^n$ is isomorphic to a subgroup of $\tilde{B_0}(H)$. In this paper we want to prove a similar result for the center by center by $w$ variety of groups, where $w$ is any outer commutator word

Factorization approach to generalized Dirac oscillators

We study generalized Dirac oscillators with complex interactions in (1+1) dimensions. It is shown that for the choice of interactions considered here, the Dirac Hamiltonians are pseudo Hermitian with respect to certain metric operators. Exact solutions of the generalized Dirac Oscillator for some choices of the interactions have also been obtained. It is also shown that generalized Dirac oscillators can be identified with Anti Jaynes Cummings type model and by spin flip it can also be identified with Jaynes Cummings type model

On characterisations of the input to state stability properties for conformable fractional order bilinear systems

This paper proposes for the first time the theoretical requirements that a fractional-order bilinear system with conformable derivative has to fulfil in order to satisfy different input-to-state stability (ISS) properties. Variants of ISS, namely ISS itself, integral ISS, exponential integral ISS, small-gain ISS, and strong integral ISS for the general class of conformable fractional-order bilinear systems are investigated providing a set of necessary and sufficient conditions for their existence and then compared. Finally, the correctness of the obtained theoretical results is verified by numerical example

A fingerprint based metric for measuring similarities of crystalline structures

Measuring similarities/dissimilarities between atomic structures is important for the exploration of potential energy landscapes. However, the cell vectors together with the coordinates of the atoms, which are generally used to describe periodic systems, are quantities not suitable as fingerprints to distinguish structures. Based on a characterization of the local environment of all atoms in a cell we introduce crystal fingerprints that can be calculated easily and allow to define configurational distances between crystalline structures that satisfy the mathematical properties of a metric. This distance between two configurations is a measure of their similarity/dissimilarity and it allows in particular to distinguish structures. The new method is an useful tool within various energy landscape exploration schemes, such as minima hopping, random search, swarm intelligence algorithms and high-throughput screenings