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Strong interaction at low energy, flavour physics and the search for new physics

English title Strong interaction at low energy, flavour physics and the search for new physics
Applicant Colangelo Gilberto
Number 117848
Funding scheme Project funding
Research institution Institut für Theoretische Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Theoretical Physics
Start/End 01.11.2007 - 31.10.2009
Approved amount 408'107.00
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Keywords (10)

strong interactions; effective field theories; chiral perturbation theory; dispersion relations; finite volume effects; grand unified theories; supersymmetry; kaon decays; lattice QCD; quark masses

Lay Summary (English)

Lay summary
In particle physics there is a general effort worldwide to find effects which cannot be explained by the "standard model" - the generally accepted theory of particle interactions. This effort is carried out along two main
allies: the high-energy and the high-precision ones. By increasing the energy of the events observed in laboratory one tries to produce new particles, not present in the standard model. By increasing the precision of the measurements of the decays of known particles one tries to see deviations from what the standard model predicts -- in this case the evidence of new particles is only indirect.

The goal of this project is to improve the precision of the theoretical calculations of decay modes of known particles and so to match the increasing experimental precision in the corresponding measurements. Only in this manner one can obtain convincing evidence of new effects from experimental measurements. The difficulty of the theoretical calculations lies in the presence of strong interactions -- although we have a theory which we believe describes them exactly (quantum chromodynamics, or QCD), we are not yet able to calculate observables, within this theory, to the desired level of precision. With this aim we will use methods like effective field theories or dispersion relations and collaborate with colleagues which use the numerical approach to deal with the strong interactions (lattice QCD).

Moreover we will study in which specific processes one should expect new effects, by considering a popular extension of the standard model which incorporates a new, yet unobserved symmetry, called supersymmetry. According to the latter, every particle present in the standard model and observed so far should have a partner with spin changed by half a unit. Moreover, instead of only one Higgs doublet (the only particle in the standard model which is yet unobserved), there should be two. If supersymmetry were exact, these new particles should have the same mass as their standard model partner, but it is expected that supersymmetry is broken and that the new particles are all heavier. Through quantum effects, however, their effects would be visible even in the decays of the observed standard model particles. One of the goal of this project is to predict where one should see some of these effects and once these are seen, to draw conclusions about the spectrum (the masses) of the new particles.
In this manner one can connect the high-precision and the high-energy frontiers in experimental particle physics.

This project is heavily connected and intertwined with the activity of a European network called FLAVIAnet, whose web page can be found here:
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
137518 Strong interaction at low energy, flavour physics and the search for new physics 01.11.2011 Project funding
126798 Strong interaction at low energy, flavour physics and the search for new physics 01.11.2009 Project funding