Ayres Freitas

  • Professor
  • Director of Graduate Studies
403 Allen Hall
(412) 624-9060


My research mostly deals with the phenomenology of new particles and interactions at colliders. The breaking of the electroweak symmetry and the stabilization of the electroweak scale has inspired ideas like the Higgs mechanism, supersymmetry, extra dimensions, technicolor and little Higgs models. However, a broader understanding may be reached with more model-independent approaches, such as effective field theories and simplified models.

I am studying how the parameters of these model-independent frameworks can be constrained by direct searches at high-energy colliders, such as the Large Hadron Collider, and by precision experiments at lower energies and future e+e- colliders. Of special interest to me are precision analyses that would allow to reconstruct the underlying framework of a model from experimental data. On the technical side, this involves development of loop calculation techniques and Monte-Carlo tools. 

Some of the new physics models quite naturally could explain the origin of ordinary matter and/or dark matter in the universe. This opens up striking connections between collider physics and astrophysics and cosmology.

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Selected Publications

  • "Probing dark sector fermions in Higgs precision studies and direct searches", A. Freitas, Q. Song, arXiv:2308.13030 (2023)
  • "Fermionic electroweak NNLO corrections to e+e-→ZH with polarized beams and different renormalization schemes", A. Freitas, Q. Song, K. Xie,  Phys. Rev. D 108, 053006 (2023)
  • "GRIFFIN: A C++ library for electroweak radiative corrections in fermion scattering and decay processes," L. Chen, A. Freitas, SciPost Phys. Codeb. 2023, 18 (2023)
  • "Two-Loop Electroweak Corrections with Fermion Loops to e+e→HZ", A. Freitas, Q. Song, Phys. Rev. Lett. 130, 031801 (2023)
  • "Hadronic effects in Møller scattering at NNLO," J. Erler, R. Ferro-Hernández, A. Freitas, JHEP 2208, 183 (2022)
  • "Evaluation of multiloop multiscale Feynman integrals for precision physics," I. Dubovyk, A. Freitas, J. Gluza, K. Grzanka, M. Hidding, J. Usovitsch, Phys. Rev. D 106, L111301 (2022)
  • "Renormalizable models of flavor-specific scalars," B. Batell, A. Freitas, A. Ismail, D. McKeen, M. Rai, Phys. Rev. D 104, 115032 (2021)
Full publication list  

Postdoctoral Affiliates

Matthew Low

Graduate Advisor

Jackson Wallace