Magnetic and quadrupole moments of light spin-1 mesons in light cone QCD sum rules

Abstract

The magnetic and quadrupole moments of the light-vector and axial-vector mesons are calculated in the light cone QCD sum rules. Our results for the static properties of these mesons are compared with the predictions of lattice QCD as well as other approaches existing in the literature.

Determination of the properties of vector mesons in external magnetic field by quenched SU(3) lattice QCD

“…the prediction of the QCD sum rules 2.0 ± 0.4 [43] and the lattice results [27,41]. Any dependence of the g-factor on the strange quark mass has not been observed within the error range.…”

“…The g-factor of the ρ meson has been calculated in [29] using the chiral EFT at varying quark masses with a result similar to ours. The light cone QCD sum rules predict the value g = 2.4 ± 0.4 [43], and the covariant quark model gives g = 2.14 [44]. Figure 6 shows the energy squared of K * ± meson with the spin projection s z = ±1 for the lightest pion mass m π = 331(7) MeV, for the strange quark mass defined by the ratio m s /m u = 20, 25, 30 and for pion mass m π = 395(6) MeV, m s = 20m u .…”

Quadrupole moments of the ρ meson and the S -wave deuteron and some general constraints on quadrupole moments of spin-1 systems

“…In what follows we consider systems with weak coupling using the wave function (20) normalized to unity. The systems with the most strong coupling are realized in the model with the square-law confinement.…”

“…So, it is clear that the theory of such properties based on different nonperturbative approaches is in the focus of investigations for years. Let us mention for example different forms of Dirac relativistic dynamics [1][2][3][4][5][6][7][8][9][10][11][12], approaches based on the Dyson-Schwinger equation [13][14][15][16], the Nambu-Jona-Lasinio model [17,18], QCD sum rules [19,20], the light front diagram technique [21], lattice calculations [22][23][24][25]. The quadrupole moment of two-particle spin one systems with total electric charge equal to unity with S-state of the relative motion of constituents is of particular interest because the existence of the quadrupole form factor and the quadrupole moment in such systems is a purely relativistic effect.…”

The evolution of meson masses in a strong magnetic field

“…On the theoretical side the main directions of research in this area are the lattice studies [20,21]- [31], [32]- [43], the chiral Lagrangians with MF [44]- [50,51], effective hadron Lagrangians [1,2,[52][53][54][55][56], [57]- [60], and recently developed path integral Hamiltonians (PIH) [62]- [68], and the chiral Lagrangian with quark degrees of freedom [69].…”