In spite of the successes of the SM, there are still three striking experimental observations for which it offers no answer: neutrino masses, the baryon asymmetry of the Universe and the observed dark matter (DM) for which it offers no candidate. These three observations strongly suggest the need of new physics. Our research objectives, are therefore to explore extensions of the SM that can explain these evidences. There are also important questions from the theoretical side:

  • is the fundamental scalar discovered at LHC exactly the SM Higgs?
  • can we extend the Higgs sector and understand new sources of CP violation?
  • can we understand and compute the baryon asymmetry of the Universe?
  • can we understand the origin of the observed DM?
  • is lepton flavour violated also in the charged lepton sector?
  • can we understand the stability of the small mass of the Higgs boson compared with the Planck scale (hierarchy problem)?
  • what is the origin of the proton spin?
  • can we understand the meson and baryon electromagnetic form factors determined in new experiments in hadron physics?

To answer these questions research at CFTP includes many hot topics in theoretical particle physics and cosmology : Fermion Masses & Mixing, CP Violation, Baryogenesis, Leptogenesis, Neutrino Physics, B Physics, Supersymmetry, LFV, Extra Dimensions, Cosmology, Dark Matter & Dark Energy, Inflation, Nuclear Physics, Hadronic Matter, Chiral Symmetry, Confinement. Please see also our list of publications We have also a strong interaction with experimental groups at LIP and at CERN, in particular a group working at CMS-CERN.

These questions, at the frontier of the field, are aligned with the big experimental effort being done or planed for the next decade, in particular at CERN and JLab. These questions are connected in many ways and we organize ourselves in four main lines of research that cover all the above topics

HIGGS PHYSICS

Research Team: G.C. Branco, D. Emmanuel-Costa, R. González Felipe, F. Joaquim, L. Lavoura, M.N. Rebelo, J.P. Silva, J. I. Silva-Marcos, J. C. Romao and Long Term Visiting Professor F. Botella (U.Valencia)

Since the SM gauge group does not determine the number of scalars, the pressing phenomenological question is to determine how many fundamental scalars there are and what their exact nature is. An extended Higgs sector may give new sources of CP violation with important implications for Neutrino Physics and Leptogenesis. It can allow for the possibility of having spontaneous CP violation, and in some extensions together, with the inclusion of at least one vectorial quark, allow for a common origin for all CP violations. It can also provide a viable DM candidate. Included in this topic are the study of the origin of fermion masses and mixing, CP violation at B factories, baryogenesis, Physics at colliders and flavor Physics.

Click here for more information about the research activity of this sub-group.

NEUTRINO PHYSICS

Research Team: G.C. Branco, D. Emmanuel-Costa, R. González Felipe, F. Joaquim, L. Lavoura ,João Pulido , M.N. Rebelo, J. C. Romão, J.I. Silva-Marcos and Long Term Visiting Professor J. W. F. Valle (U.Valencia)

Oscillation experiments have achieved high precision in determining the neutrino mass and mixing pattern. The most important new result is the theta13 mixing angle recently measured by the Daya-Bay and RENO reactor experiments. The fact that theta13 is not close to zero may allow for the discover of CP violation in the lepton sector. The old and long standing mystery regarding the origin of fermion masses and mixing seems now even more intriguing: why are the neutrino masses very suppressed and mixings large, in contrast with what is observed in the quark sector. Included in this topic are the study of neutrino-mass generation mechanisms, neutrino Oscillations, CP-Violation in the Leptonic sector and Baryogenesis through leptogenesis. Grand Unified Theories, with an extended Higgs sector are also under study in this topic, as well as models dor Dm from the Higgs sector.

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FERMION MASSES AND MIXING, CP VIOLATION, AND BARYOGENESIS 

Research Team: G.C. Branco, D. Emmanuel-Costa, R. González Felipe, F. Joaquim, L. Lavoura, P.A. Parada ,João Pulido , M.N. Rebelo, J.P. Silva, J.I. Silva-Marcoss and Long Term Visiting Professor F. Botella (U.Valencia)

The origin of fermion masses and mixing and of CP violation are some of the major outstanding problems in particle physics. These members of CFTP have been working actively in CP violation, as well as in attempts at understanding the observed patterns of fermion masses and mixing, both in the quark and in the leptonic sector. We are especially interested in pursuing the following topics of research: Family symmetries and patterns of neutrino mass matrices; Baryogenesis through leptogenesis; CP violation at B factories; Physics at colliders.

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SUPERSYMMETRY

Research Team: J.C. Romão, G.C. Branco, F. Joaquim, D. Emmanuel-Costa, L. Lavoura

Supersymmetry (SUSY) allows for deviations from the SM that are very small at the electroweak scale, while offering a solution to the hierarchy problem and provide a DM candidate. Also SUSY seesaw models offer an explanation for the smallness of the neutrino masses and open a window into charged LFV. The experimental search for SUSY plays an important role in the analysis of the LHC data. The present indication of a light Higgs boson with mass around 125 GeV is compatible with a heavy spectrum. The next phase of LHC at 14 TeV will be crucial to find out if this beautiful idea plays a role at present energies. Included in this topic are supersymmetric unification, supersymmetric neutrino-mass generation mechanisms, CP violation in supersymmetry, Lepton-flavour violation (LFV), and Drak Matter.

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HADRON PHYSICS

Research Team: P. Bicudo, T. Peña and Alfred Stadler, also in collaboration with Jefferson Laboratory

In this area, our general objective is to create innovative theoretical methods to interpret data from large experimental infrastructures (e.g. at Jlab, HADES, PANDA/FAIR, LHCb). Meson and baryon electromagnetic form factors are among the most fundamental observables in hadron physics and they will be a focus of our activity. They are essential for the puzzle of connecting the observed properties of mesons and baryons and the underlying QCD quark-gluon dynamics. Also the interpretation of the nuclear matter emissivity from experiments of elementary reactions and of heavy ion collisions, needs a detailed knowledge of those form factors in the timelike region. Our approach in Minkowski space makes our group unique because it enables calculations of transition form factors in the timelike region, where lattice QCD and the Dyson-Schwinger approach do not work yet. We aim to contribute to the new accuracy era made possible by the LHC. The interpretation of recent data from the LHCb detector on exotic quark structures, as tetraquarks, and on quarkonia states from the CMS detector, demands precision spectroscopic calculations that supersede the old generation of quark models of the 1980's.

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CMS EXPERIMENT AT CERN

We have a strong interaction with this experimental group of LIP/CMS.

Research Team: J. Seixas and Long Term Visiting Researcher Pietro Faccioli (CERN):

The Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), presently in operation at CERN. studies very high energy collisions of proton and nuclear beams with the goal of investigating the most fundamental properties of matter and, in particular, the study of the nature of the electroweak symmetry breaking and the origin of mass, exploiting the discovery opportunities offered by the new LHC energy.

The activities of the LIP/CMS group include:

1. Proton-proton physics, in particular measurement of Top quark properties, Higgs boson and SUSY searches;
2. Heavy-Ion physics, with the study of the quark-gluon plasma through measurements of quarkonia production;
3. Hardware and software for the trigger and the readout system of the electromagnetic calorimeter;
4. New detector developments for the CMS Upgrade program.

More information at LIP/CMS experiment at CERN.