Stringy black holes and Wald entropy

Thomas Ortin

IFT, Madrid

Wed, Jan. 25th 2023, 14:15

Salle Claude Itzykson, Bât. 774, Orme des Merisiers

In order to test whether the microscopic entropy computed by
string/(AdS/CFT) methods matches the macroscopic one for stringy black
holes at higher orders in alpha' it is crucial to have a reliable
computation of the latter. A prominent candidate is the quantity that
plays the role of the entropy in the first law of black hole
thermodynamics for any matter-free diff-invariant theory: the Wald
entropy. Iyer and Wald gave a widely used prescription to compute it when
the matter fields are tensors. However, in the case of the black-hole
solutions of the heterotic superstring effective action to first order in
alpha' the entropy obtained using this prescription fails to satisfy the
first law.
The main reason for this failure is the fact that most matter fields have
gauge freedoms and, therefore, they are not tensors.
In this talk I will show how to compute the diffeomorphism Noether charge
(Wald entropy) by dealing correctly with the gauge freedoms of the matter
fields. I will apply this methodology to different theories including the
heterotic superstring effective action to first order in alpha'. The
resulting formula will be used to compute the alpha' corrections to the
entropy of the several black-hole solutions of the heterotic superstring
effective action to first order in alpha'.

Contact : Ioannis
TSIARES