SPS Journal Club: ‘Generalised anomalies, QCD, and holography’

Title: ‘Generalised anomalies, QCD, and holography’

Speaker: Mohammad Akhond (Dipartimento di Fisica & INFN, Università di Roma  “Tor Vergata”)

Venue & Time: Red Room / 12:00

Abstract: During the last decade, the notion of an ‘t Hooft anomaly has been generalised to the case of discrete symmetries. An interesting instance, discussed by Tanizaki, is the mixed anomaly between the discrete axial symmetry and the flavour and baryonic symmetries in massless QCD. The goal of this talk is to provide a derivation of this anomaly from a top-down holographic dual of QCD. I will show that the topological couplings in the bulk supergravity dual of the D4-D8 system encode Tanizaki’s anomaly, once fluctuations around the bulk gauge fields are turned on. A technical challenge for this computation is the difficulty in maintaining gauge invariance of supergravity theories in the presence of D-branes. To overcome this issue, a compact formulation of the flux sector of (massive) type IIA supergravity in the presence of D8 branes is presented.