We show that a basic difference between the electron- and hole-doped cuprates is their proximity to two different quantum critical points in a 2D free fermion system on a square lattice and that the spin dynamics observed recently for the first time in the electron-doped Nd2-xCexCuO4, very different from that in the hole-doped cuprates, can be understood as a consequence of this effect.

Square-root topological phases have been discussed mainly for systems with chiral symmetry. In this paper, we analyze the topology of squared Hamiltonian preserving time-reversal and particle-hole Our analysis elucidates that two-dimensional class CII host helical edge states due to nontrivial in contrast absence ordinary phases. The emergence modes is demonstrated by analyzing a toy model. We ...

The ground state energy dispersion curve of a single mobile hole in the two-dimensional t-J model is studied numerically by means of the Green function Monte Carlo method on square lattices of various sizes up to 16 16. Transient estimation results show evidence of a gap of the order of 0:2 t, in the physical region of the model, between the energy value at k = (=2; =2), which corresponds to th...

A well known result of Fraenkel and Simpson states that the number of distinct squares in a word of length n is bounded by 2n since at each position there are at most two distinct squares whose last occurrence start. In this paper, we investigate the problem of counting distinct squares in partial words, or sequences over a finite alphabet that may have some “do not know” symbols or “holes” (a ...

We critically assess the role of the Blandford-Znajek mechanism in the powering of outflows from accretion disk-fed black holes. We argue that there is no reason to suppose that the magnetic field threading the central spinning black hole differs significantly in strength from that threading the central regions of the disk. In this case, we show that the electromagnetic output from the inner di...

We theoretically investigate the Fermi-edge singularity in a spin-incoherent Luttinger liquid. Both cases of finite and infinite core hole mass are explored, as well as the effect of a static external magnetic field of arbitrary strength. For a finite mass core hole the absorption edge behaves as (omega-omega th)alpha/square root of absolute value (ln(omega-omega th)) for frequencies omega just...

If supermassive black holes in centres of galaxies form by merging of black-hole remnants of massive Population III stars, then there should be a few black holes of mass one or two orders of magnitude smaller than that of the central ones, orbiting around the centre of a typical galaxy. These black holes constitute a weak perturbation in the gravitational potential, which can generate wave phen...

We describe a one-parameter family of models of stable spherical stellar systems in which the phase-space distribution function depends only on energy. The models have similar density pro les in their outer parts ( / r 4 ) and central power-law density cusps, / r 3 , 0 < 3. The family contains the Ja e (1983) and Hernquist (1990) models as special cases. We evaluate the surface brightness pro l...