[Depfis] 73 encuentro de la red strings en ar

[carmen en iafe.uba.ar]

Estimados colegas y amigos:

Tenemos el agrado de anunciar el 73º encuentro de la red Strings en ar, que
tendrá  lugar en el Instituto de Astronomía y Física del Espacio (IAFE),
Ciudad Universitaria de Buenos Aires, el jueves 13 de junio de 2019, desde
las 13:30hs

El programa se detalla a continuación:

13.30-14.30 Gullem Perez-Nadal (IFIBA-UBA-CONICET)
"Modular Hamiltonian of a chiral fermion on the torus"

Abstract: Modular Hamiltonians are central to the study of entanglement in
QFT, and they have played a key role in important advances such as the
proof of the averaged null energy condition and the formulation of a
well-defined version of the Bekenstein bound. However, very few modular
Hamiltonians are known explicitly. In this talk I will present a recent
paper (arXiv:1905.05210) in which, for the first time, we computed the
modular Hamiltonian of a massless Dirac fermion on a circle at non-zero
temperature.

14:30-15.00 Coffee break

15.00-16.00 Aníbal Medina (IFLP-CONICET)
"SUSY Implications from WIMP Annihilation into Scalars at the Galactic
Centre"

Abstract: An excess in gamma-rays emanating from the galactic centre has
recently been observed in the Fermi-LAT data. A possible interpretation of
this signal is due to WIMP annihilation, with the spectrum well-fit from
dark matter annihilating dominantly to either bottom-quark or Higgs pairs.
Supersymmetric models provide a well-motivated framework to study the
implications of this signal in these channels. With a neutralino dark
matter candidate, the galactic excess can not be easily accommodated in
the minimal supersymmetric model, which in any case requires tuning below
the percent level to explain the observed Higgs mass.
Instead we are naturally led to consider the next-to-minimal model with a
singlet superfield. The singlet admixture allows for annihilation via a
light pseudoscalar mediator into bottom-quark pairs and the annihilation
into a Higgs-pseudoscalar pair is possible because the three-point scalar
coupling can now be enhanced. In fact we show that the fit to the
Higgs-pseudoscalar channel can be just as good as for the bottom-quark
pairs. Moreover, in the parameter range of interest, the next-to-minimal
supersymmetric model solves the $\mu$-problem and can explain the 125 GeV
Higgs mass with improved naturalness.

We also consider an extension by adding a right-handed neutrino field with
the right-handed sneutrino acting as a possible dark matter candidate.
Interestingly this allows for the annihilation into pseudoscalar pairs
which also provide a good fit to the gamma-ray spectrum. Furthermore in
the case of a neutralino LSP, the late decay of a sneutrino NLSP can
non-thermally produce the observed relic abundance.

16.00-16:30 Coffee break

16:30-17:30 Pablo Bueno (CAB)
"New results on the entanglement entropy of singular regions in CFTs"

Abstract:
I will present new results involving the structure of divergences and
universal terms of the entanglement and Rényi entropies for singular
regions. I will start with a quick review of previous results in various
dimensions. Then, I will argue that for (3+1)-dimensional free CFTs,
entangling regions emanating from vertices give rise to a universal
quadratically logarithmic contribution controlled by a local integral over
the curve formed by the intersection of the entangling surface with a unit
sphere centered at the vertex. While for circular and elliptic cones this
term reproduces the general-CFT result, it vanishes for polyhedral
corners. For those, I will argue that the universal contribution, which is
logarithmic, is not controlled by a local integral, but rather it depends
on details of the CFT in a complicated way, contrary to previous
expectations. I will also refute a previous conjectural relation between
the contribution coming from a wedge in (3+1) dimensions and the one
corresponding to a corner region of the same opening angle in the (2+1)
dimensions. Finally, I will show that the mutual information of two
regions that touch at a point is not necessarily divergent, as long as the
contact is through a sufficiently sharp corner and I will provide examples
of singular entangling regions which do not modify the structure of
divergences of the entanglement entropy compared with smooth surfaces.
Based on: arXiv:1904.11495, coauthored by Horacio Casini and William
Witczak-Krempa

Esperamos verlos el jueves 13/6

Saludos cordiales,
José Edelstein
Nicolas Grandi
Carmen Núñez
Martín Schvellinger