Can Eta mesons have a magnetic moment ?

The response of pseudoscalar and vector mesons to strong magnetic fields is studied within a simple constituent quark model using analogy with bound states of Positronium. Magnetic moments of charged vector mesons K*, D*, B* are predicted and it is found that Eta mesons have magnetic polarizability. In extremely strong magnetic fields, behaviour of J/Psi mesons is discussed. We speculate on the existence of an induced magnetic moment of Eta meson.Comment: 4 pages, 2 figures, contribution to SPIN2012 conference proceedings (to appear in Physics of Elementary Particles and Atomic Nuclei journal

Magnetic Polarizability of Virtual (ss') and (cc') Pairs in the Nucleon

We suggest 3P0 quantum state of virtual (ss') pairs in the nucleon can be polarised by the internal fields permeating the volume of the nucleon (proton or neutron). Due to the quadratic Zeeman interaction, 3P0 wavefunction of virtual (qq') pairs acquires the admixture of 1P10 quantum state in the magnetic field, which generates the antiparallel polarization of s and s' quarks (in the nucleon). Considering the internal magnetic fields of neutron and proton (originating from their measured magnetic dipole moments), we suggest the induced s-quark polarization in the neutron to be of the oposite direction compared to the proton case. We mention the influence of the internal chromo-magnetic fields on the quantum state of (qq') pairs in the nucleon and we discuss also the expected behaviour of virtual (cc') pairs.Comment: 4 pages, 1 figure, prepared for DSPIN 2017 conference proceeding