Seiberg duality

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In

) and an N=1 chiral QCD with N_f-N_c colors and N_f flavors, where N_c and N_f are positive integers satisfying

${\displaystyle N_{f}>N_{c}+1}$.

A stronger version of the duality relates not only the chiral limit but also the full deformation space of the theory. In the special case in which

${\displaystyle {1 \over 3}N_{f}<N_{c}<{2 \over 3}N_{f}}$

the IR fixed point is a nontrivial interacting

anomalous scaling dimension

of a chiral superfield ${\displaystyle D={\frac {3}{2}}R}$ where R is the R-charge. This is an exact result.

The dual theory contains a fundamental "meson" chiral superfield M which is color neutral but transforms as a bifundamental under the flavor symmetries.

	SQCD	dual theory
color gauge group	${\displaystyle SU(N_{c})}$	${\displaystyle SU(N_{f}-N_{c})}$
global internal symmetries	${\displaystyle SU(N_{f})_{L}\times SU(N_{f})_{R}\times U(1)_{B}\times U(1)_{R}}$	${\displaystyle SU(N_{f})_{L}\times SU(N_{f})_{R}\times U(1)_{B}\times U(1)_{R}}$
chiral superfields	${\displaystyle Q\,(N_{f},1)_{1/N_{c},(N_{f}-N_{c})/N_{f}}}$	${\displaystyle {\tilde {Q}}\,(1,N_{f})_{-1/(N_{f}-N_{c}),N_{c}/N_{f}}}$
	${\displaystyle Q^{c}\,(1,{\overline {N_{f}}})_{-1/N_{c},(N_{f}-N_{c})/N_{f}}}$	${\displaystyle {\tilde {Q^{c}}}\,({\overline {N_{f}}},1)_{1/(N_{f}-N_{c}),N_{c}/N_{f}}}$
		${\displaystyle M\,(N_{f},{\overline {N_{f}}})_{0,2(N_{f}-N_{c})/N_{f}}}$

The dual theory contains the superpotential ${\displaystyle W=\alpha M{\tilde {Q^{c}}}{\tilde {Q}}}$.

Relations between the original and dual theories

Being an S-duality, Seiberg duality relates the strong coupling regime with the weak coupling regime, and interchanges chromoelectric fields (

The mesons and baryons are preserved by the duality. However, in the electric theory the meson is a quark bilinear (${\displaystyle M\equiv Q^{c}Q}$), while in the magnetic theory it is a fundamental field. In both theories the baryons are constructed from quarks, but the number of quarks in one baryon is the rank of the gauge group, which differs in the two dual theories.

The

Evidence for Seiberg duality

The moduli spaces of the dual theories are identical.

The global symmetries agree, as do the charges of the mesons and baryons.

In certain cases it reduces to ordinary electromagnetic duality.

It may be embedded in string theory via Hanany–Witten brane cartoons consisting of intersecting D-branes. There it is realized as the motion of an NS5-brane which is conjectured to preserve the universality class.

Six nontrivial anomalies may be computed on both sides of the duality, and they agree as they must in accordance with Gerard 't Hooft's anomaly matching conditions. The role of the additional fundamental meson superfield M in the dual theory is very crucial in matching the anomalies. The global gravitational anomalies also match up as the parity of the number of chiral fields is the same in both theories. The R-charge of the Weyl fermion in a chiral superfield is one less than the R-charge of the superfield. The R-charge of a gaugino is +1.

't Hooft anomaly matching conditions

anomaly	SQCD	dual theory
${\displaystyle SU(N_{f})_{L}^{3}}$	${\displaystyle N_{c}d^{(3)}(N_{f})}$	${\displaystyle N_{c}d^{(3)}(N_{f})}$
${\displaystyle SU(N_{f})_{L}^{2}U(1)_{B}}$	${\displaystyle d^{(2)}(N_{f})}$	${\displaystyle d^{(2)}(N_{f})}$
${\displaystyle SU(N_{f})_{L}^{2}U(1)_{R}}$	${\displaystyle -{\frac {N_{c}^{2}}{N_{f}}}d^{(2)}(N_{f})}$	${\displaystyle {\frac {-N_{c}^{2}}{N_{f}}}d^{(2)}(N_{f})}$
${\displaystyle U(1)_{R}}$	${\displaystyle -N_{c}^{2}-1}$	${\displaystyle -N_{c}^{2}-1}$
${\displaystyle U(1)_{R}^{3}}$	${\displaystyle -2{\frac {N_{c}^{4}}{N_{f}^{2}}}+N_{c}^{2}-1}$	${\displaystyle -2{\frac {N_{c}^{4}}{N_{f}^{2}}}+N_{c}^{2}-1}$
${\displaystyle U(1)_{B}^{2}U(1)_{R}}$	${\displaystyle -2}$	${\displaystyle -2}$

Another evidence for Seiberg duality comes from identifying the superconformal index, which is a generalization of the Witten index, for the electric and the magnetic phase. The identification gives rise to complicated integral identities which have been studied in the mathematical literature.^[2]

Generalizations

Seiberg duality has been generalized in many directions. One generalization applies to

Whether Seiberg duality exists in 3-dimensional nonabelian gauge theories with only 4 supercharges is not known, although it is conjectured in some special cases with Chern–Simons terms.^[4]

References