We prove that the purely imaginary square well generates an infinite number of bound states with real energies. In the strong-coupling limit, our exact PT symmetric solutions coincide, utterly unexpectedly, with their textbook, well known Hermitian predecessors. PACS 03.65.Bz, 03.65.Ge February 1, 2008, sho.tex file

The systematic approach to study bound states in quantum chromodynamics is presented. The method utilizes nonperturbative flow equations in the confining background, that makes possible to perform perturbative renormalization and to bring the QCD Hamiltonian to a block-diagonal form with the number of quasiparticles conserving in each block. The effective block-diagonal Hamiltonian provides con...

Cluster formation in strongly interacting Fermi-systems is one of the most interesting subjects in many body physics. So far, in condensed matter, only the study of formation of two body clusters has been studied in a wide perspective in the context of pairing, that is superfluidity and superconductivity (see e.g.1 in the context of cold atoms). However, in nuclear physics, due to the existence...

Several series of shallow large-size (l ≫ lattice spacing) two-hole bound states are found in the two-dimensional t−J model. Their binding energies depend exponentially on the inverse value of the hole-spin-wave coupling constant. Their parity is connected with the angular wave function in a nonstandard way. The possible role of these states in the formation of superconducting pairing is consid...

We introduce three distinct, yet equivalent, optimization procedures for the Fourier Spectral Method which increase its accuracy. This optimization procedure also allows us to uniquely define the error for the cases which are not exactly solvable, and this error matches closely its counterpart for the cases which are exactly solvable. Moreover, this method is very simple to program, fast, extre...

Lowest-order cross sections for q q production and annihilation can be approximately corrected for higher-order QCD e ects by using a corrective Kfactor. For energies where quark masses cannot be ignored, the K-factor is dominated by the wave function distortion arising from the initialor nalstate interaction between the quark and the antiquark. We evaluate this Kfactor for q q production and a...

We discuss formation of an S-wave bound state in finite volume on the basis of Lüscher’s phaseshift formula. It is found that although a bound-state pole condition is fulfilled only in the infinite volume limit, its modification by the finite size corrections is exponentially suppressed by the spatial extent L in a finite box L. We also confirm that the appearance of the S-wave bound state is a...

It is well known that the complex structure of the QCD vacuum can, in some regimes, be parametrized by local vacuum condensates, i.e. the expectation values of operators where all the perturbative vacuum fluctuations are taken out at the best of our ability . The first attempt to calculate the effect of non-perturbative vacuum condensates on the energy levels of heavy quarkonia was performed in...

The rotational invariance is violated in the lightcone quantization method when the Fock space is truncated for practical calculations. To what extent the rotation symmetry is broken in the lightcone quantization approach can be quantified by calculating the explicit rotation dependence of the two-body scattering phase shifts. We analyze the scattering phase shifts in a simple scalar field mode...

Configuration space Faddeev equations are applied to describe the ΛBe hypernucleus in the ααΛ cluster model. For calculation of resonance state energies a variant of the method of analytical continuation in coupling constant is used. To realize this method, an auxiliary three-body potential is added to the Hamiltonian of the equations. A proper choice of strength parameter of the potential conv...