Higher-spin interactions: four-point functions and beyond

Interactions : Structure Functions , Higher Twist

Third-neighbor and other four-point correlation functions of spin-1/2 XXZ chain

The correlation functions of the spin-1/2 XXZ chain in the ground state were ex-pressed in the form of multiple integrals for −1 < ∆ ≤ 1 and 1 < ∆. In particular,adjacent four-point correlation functions were given as certain four-dimensional inte-grals. We show that these integrals can be reduced to polynomials with respect tospecific one-dimensional integrals. The results ...

Phase Transitions with Four-Spin Interactions

Using an extended Lee-Yang theorem and GKS correlation inequalities, we prove, for a class of ferromagnetic multi-spin interactions, that they will have a phase transition (and spontaneous magnetization) if, and only if, the external field h = 0 (and the temperature is low enough). We also show the absence of phase transitions for some nonferromagnetic interactions. The FKG inequalities are sho...

Higher - twist Effects in Spin Structure Functions

We discuss the QCD effects of the higher-twist operators in the nucleon spin-dependent structure functions measured by the polarized deep inelastic leptoproduction. We particularly study the renormalization of the twist-3 and twist-4 operators within the framework of operator product expansions and renormalization group methods in perturbative QCD. Emphasis will be placed on the role of the ope...

Higher Twists in Spin Structure Functions from a “constituent Quark” Point of View

We discuss the implications of a “constituent quark” structure of the nucleon for the leading (1/Q–) power corrections to the spin structure functions. Our basic assumption is the presence of quark–gluon correlations in the nucleon wave function, whose size, ρ ∼ 0.3 fm, is small compared to the nucleon radius, R (two–scale picture). We argue that in this picture the isovector twist–4 matrix ele...