Pitt Seal University of Pittsburgh

Homepage of Ayres Freitas

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My working area is theoretical high energy elementary particle physics. Currently, most results both from low and high energy experiments are well described by a theory called the Standard Model. This model is larglely defined by a few symmetries, some of which must be broken. However, the Standard Model contains only an unsatisfactory explanation for these broken symmetries. In particular, the Standard Model fails to describe the origion of ordinary matter as well as dark matter in the universe. These shortcomings have spawned many new ideas like supersymmetry, extra dimensions, technicolor and little Higgs models, which all predict many new heavy particles.

My research mostly deals with the phenomenology of these new particles and their interactions at current and future colliders, most notably at the Large Hadron Collider (LHC). Furthermore, models for physics beyond the Standard Model can be constrained by existing precision data and possibly could be discovered at future experiments, most notably at the Large Hadron Collider (LHC). Of special interest to me are precision analyses that would allow to reconstruct the underlying framework of a model from experimental data. I am working on methods to determine the spin and couplings of newly discovered particles, as well as ideas to detect particles that would be particularly eluvise. One main focus has been on supersymmetric models, but also on models with extra dimensions, extended gauge groups and little Higgs models.

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.

On the technical side, development of loop calculation techniques and Monte-Carlo tools are very important for the interpretation of the flood of new data expected from the LHC. Recently there has been much progress in both areas, leading to automated computer programs. I have been working on methods for electroweak one- and two-loop calculations, as well as implementation of new models in Monte-Carlo generators.

Recent projects and publications:

Heavy Color-Octet Particles at the LHC
C.-Y. Chen, A. Freitas, T. Han, K. Lee,   arXiv:1410.8113

Leptophilic Dark Matter in Lepton Interactions at LEP and ILC
A. Freitas, S. Westhoff,   JHEP 1410 116 (2014)

Precision Measurements of Higgs Couplings: Implications for New Physics Scales
C. Englert, A. Freitas, M. Mühlleitner, T. Plehn, M. Rauch, M. Spira, K. Walz,
invited review, J. Phys. G 41, 113001 (2014)

Testing the Muon g-2 Anomaly at the LHC
A. Freitas, J. Lykken, S. Kell, S. Westhoff,   JHEP 1405, 145 (2014)

Higher-order electroweak corrections to the partial widths and branching ratios of the Z boson
A. Freitas,   JHEP 1404, 070 (2014)

Two-loop fermionic electroweak corrections to the Z-boson width and production rate
A. Freitas,   Phys. Lett. B 730, 50 (2014)

Exploring Quantum Physics at the ILC
A white paper for the Community Summer Study (a.k.a. Snowmass 2013)
A. Freitas et al.,   arXiv:1307.3962

    Complete list of publications (from INSPIRE HEP database)

Computer codes:


A Mathematica/Fortran package for the numerical computation of loop integrals using subtraction terms.

  Version 1.2 (August 2014)
  Version 1.1 (August 2012)
  Version 1.0 (May 2012)

Slepton production at lepton colliders:

NLO corrections to R-smuon production, e+e → μR+μR (Installation and user's guide)
NLO corrections to L-smuon production, e+e → μL+μL (Installation and user's guide)
NLO corrections to R-selectron production, e+e → eR+eR (Installation and user's guide)
NLO corrections to R-selectron production
in e-e- collisions
ee → eReR (Installation and user's guide)
NLO corrections to muon-sneutrino production, e+e → νμνμ* (Installation and user's guide)
NLO corrections to electron-sneutrino production, e+e → νeνe* (Installation and user's guide)

Littlest Higgs model with T-parity broken by WZW term:

CalcHEP model file