Contact Term, its Holographic Description in QCD and Dark Energy

Understand

In this work we study the well known contact term, which is the key element in resolving the so-called $U(1)_A$ problem in QCD.

• We study this term using the dual Holographic Description.
• We argue that in the dual picture the contact term is saturated by the D2 branes which can be interpreted as the tunnelling events in Minkowski space-time.
• We quote a number of direct lattice results supporting this identification.