Explanation of the central charge ratio 27/32 in four-dimensional renormalization group flows between superconformal theories.
We show that when a four-dimensional N = 2 superconformal field theory (SCFT) flows to an N = 1 SCFT via giving a mass to the adjoint chiral superfield in a vector multiplet with marginal coupling, the central charges a and c of the N = 2 theory are related to those of the N = 1 theory by a universal linear transformation as long as there are no accidental symmetries in the infrared. In the large N limit, this relationship implies that the central charges obey a_{IR}/a_{UV} = c_{IR}/c_{UV} = 27/32. This gives a physical explanation to many examples of this number found in the literature, and also suggests the existence of a flow between some theories not previously thought to be connected.
Tachikawa
Yuji
Y
School of Natural Sciences, Institute for Advanced Study, Princeton, New Jersey 08450, USA.
Wecht
Brian
B