TY - JOUR

T1 - Chiral dynamics from the hadronic string

T2 - General formalism

AU - Andrianov, A. A.

AU - Espriu, D.

AU - Prats, A.

PY - 2006/6/30

Y1 - 2006/6/30

N2 - Quantum Chromodynamics (QCD) at long distances can be described by the chiral Lagrangian. On the other hand there is overwhelming evidence that QCD and all non-Abelian theories admit an effective string description. Here we review a derivation of the (intrinsic) parity-even chiral Lagrangian by requiring that the propagation of the QCD string takes place on a background where chiral symmetry is spontaneously broken. Requiring conformal invariance leads to the equation of motion of the chiral Lagrangian. We then proceed to coupling the string degrees of freedom to external gauge fields and we recover in this way the covariant equations of motion of the gauge-invariant chiral Lagrangian at script O sign(p2). We consider next the parity-odd part (Wess-Zumino-Witten) action and argue that this requires the introduction of the spin degrees of freedom (absent in the usual effective action treatment). We manage to reproduce the Wess-Zumino-Witten term in two dimensions (2D) in an unambiguous way. In 4D the situation is considerably more involved. We outline the modification of boundary interaction that is necessary to induce the parity-odd part of the chiral Lagrangian.

AB - Quantum Chromodynamics (QCD) at long distances can be described by the chiral Lagrangian. On the other hand there is overwhelming evidence that QCD and all non-Abelian theories admit an effective string description. Here we review a derivation of the (intrinsic) parity-even chiral Lagrangian by requiring that the propagation of the QCD string takes place on a background where chiral symmetry is spontaneously broken. Requiring conformal invariance leads to the equation of motion of the chiral Lagrangian. We then proceed to coupling the string degrees of freedom to external gauge fields and we recover in this way the covariant equations of motion of the gauge-invariant chiral Lagrangian at script O sign(p2). We consider next the parity-odd part (Wess-Zumino-Witten) action and argue that this requires the introduction of the spin degrees of freedom (absent in the usual effective action treatment). We manage to reproduce the Wess-Zumino-Witten term in two dimensions (2D) in an unambiguous way. In 4D the situation is considerably more involved. We outline the modification of boundary interaction that is necessary to induce the parity-odd part of the chiral Lagrangian.

KW - Chiral symmetry breaking

KW - Effective chiral Lagrangian

KW - Hadronic string

UR - http://www.scopus.com/inward/record.url?scp=33746078116&partnerID=8YFLogxK

U2 - 10.1142/S0217751X06031314

DO - 10.1142/S0217751X06031314

M3 - Article

AN - SCOPUS:33746078116

VL - 21

SP - 3337

EP - 3365

JO - International Journal of Modern Physics A

JF - International Journal of Modern Physics A

SN - 0217-751X

IS - 16

ER -