In a vector-like extension of the minimal standard model with mirror fermions leptoquarks can be bound states of fermion-mirror-fermion pairs held together by a new strong interaction at the TeV scale. The small couplings of leptoquarks to light fermion pairs arise due to mixing. The large Q event excess at HERA and also the high ET jet excess at Tevatron can potentially be explained.

We present analytic expressions for the vacuum polarization effects due to a light fermion with finite mass in the binding energy and in the wave function at the origin of QED and (weak coupling) QCD non-relativistic bound states. Applications to exotic atoms, Υ(1s) and tt̄ production near threshold are briefly discussed. Preprint submitted to Elsevier Preprint 7 February 2008

Recent results on the QCD analysis of bound states of heavy ¯ qq quarks are reviewed, paying attention to what can be derived from the theory with a reasonable degree of rigour. We report a calculation of ¯ bc bound states; a very precise evaluation of b, c quark masses from quarkonium spectrum; the NNLO evaluation of Υ → e + e − ; and a discussion of power corrections. For the b quark pole mas...

This is a correction to the author’s article [Multiscale Model. Simul., 10 (2012), pp. 383–417].

We study the Laplacian in L 2 (R 3) perturbed on an infinite curve Γ by a δ interaction defined through boundary conditions which relate the corresponding generalized boundary values. We show that if Γ is smooth and not a straight line but it is asymptotically straight in a suitable sense, and if the interaction does not vary along the curve, the perturbed operator has at least one isolated eig...

We argue that supersymmetric gluodynamics (theory of gluons and gluinos) has a condensate-free phase. Unlike the standard phase, the discrete axial symmetry of the Lagrangian is unbroken in this phase, and the gluino condensate does not develop. Extra unconventional vacua are supersymmetric and are characterized by the presence of (bosonic and fermionic) massless bound states. A set of argument...

We consider a (2 + 1)-dimensional massless Dirac equation in the presence of complex vector potentials. It is shown that such vector potentials (leading to complex magnetic fields) can produce bound states, and the Dirac Hamiltonians are η-pseudo Hermitian. Some examples have been explicitly worked out.