electroweak symmetry breaking strongly...

The SM is not a final theory of everything. What is beyond the SM? How to include gravity? Even within the SM model itself a big problem remains unsettled: where masses of particles come from? It is likely that the answer to this single question will lead us beyond the SM.

There is a host of hypotheses about New Physics beyond the SM. Some include supersymmetry. Some result in introduction of new strong interactions and new substructure of SM particles. Some introduce extra dimensions, straight or warped. Some predict a Higgs boson, one or more. In some there is none. Only one thing is clear: the decision on the correct theory lies in future experiments like LHC and ILC.

In the absence of the SM Higgs boson, many SM scattering amplitudes would violate the tree-level S-matrix unitarity at a TeV scale. The unitarity can be restored by new particles, fundamental or composite.

Beside predicting a substructure for some of SM particles the models of New Strong Physics generally predict the existence of new bound states. These would occur in various collision processes as new resonances, if the collision energy is high enough. Otherwise New Physics can demonstrate itself through indirect effects: deviations from the SM observed in precision measurements.

If New Strong Physics is tied with mass generating mechanism it is likely that the new resonances couple predominantly to the heaviest SM particles, the elweak gauge bosons and the top quark.

Since the SM has been succesfully tested to a very high precision any New Physics must include the SM as its low-energy approximation. This sets grounds for a model independent description of New Physics. We can build an effective Lagrangian using known fields and symmetries of the SM. We end up with extra terms not found in the SM Lagrangian. These can parameterize the influence of New Physics below its scale.

BESS-like Model of Strong ESB and Its Phenomenology

  • working team: M.Gintner, I.Melo, B.Trpišová
  • abstract: We formulate the BESS-model-like effective description of New Strong Physics. Beside the SM fields new vector-like resonance (spin=weak_isospin=1) is introduced into the effective Lagrangian based on the non-linear sigma-model. There is no Higgs particle in the spectrum and the resonance is introduced as an SU(2)_V gauge boson. The resonance couples directly to the W and Z bosons and to the third generation of the SM quarks, only. To other SM fermions it couples through mixing with the SM gauge bosons, only. In our project we investigate signatures of the model in various LHC and ILC processes. We calculate tree-level cross sections and generate events of the signal and background processes using CompHEP endowed with our implementation of the model. Then, within the ATHENA environment the events are decayed and hadronized with PYTHIA. Next, ATLFAST takes care of the detector effects and reconstruction of jets. Finally, the events are reconstructed with ROOT.


SM = Standard Model, ESB = Electroweak Symmetry Breaking, LHC =Large Hadron Collider, ILC = International Linear Collider, BESS = Breaking Electroweak Symmetry Strongly