Physics at CFTP and the Nobel Prize 2008

It is with great excitement that, at CFTP, we received the news that the Nobel Prize for Physics for 2008 has been awarded to Yoichiro Nambu, Makoto Kobayashi and Toshihide Maskawa.

Yoichiro Nambu got the prize "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics". Today, this idea is incorporated in all the modern theories of Particle Physics, namely in the so-called Higgs mechanism, that is responsible for giving masses to the Standard Model Particles, and predicts one particle, the Higgs boson that soon will searched for in the LHC at CERN. Also Nambu's ideas had a strong impact on hadronic Physics - chiral symmetry, and its spontaneous breaking, is one essential feature of QCD, and is responsible for essential features of the structure of hadrons, and their interaction or couplings. This is currently one of the research interests at CFTP (Teresa Peña, João Seixas, Pedro Bicudo ) focusing on predictions for the meson and baryon spectra, and the nuclear interaction.

Makoto Kobayashi e Toshihide Maskawa were awarded the prize "the proposal of a successful mechanism for CP violation in the Standard Model", which is one of the hot topics of research at CFTP. Their work, and our research, are also intimately related to the Creation of Matter in the Universe, as well as to the understanding of fermion masses and mixing, the so-called Mass Problem, one of the most profound questions in Fundamental Physics.

The recent measurement of gamma by BaBar and Belle provided irrefutable evidence that the CKM (Cabibbo Kobayashi and Maskawa) matrix is indeed complex thus confirming the pioneering proposal of Kobayashi and Maskawa in 1973. This important conclusion was also stated in works involving collaborations of CFTP members, e.g. in New physics and evidence for a complex CKM, Nucl. Phys. B 725 (2005) 155 by F.J. Botella, G.C. Branco, M. Nebot and M.N. Rebelo or in Yukawa Textures, New Physics and Nondecoupling published in Phys. Rev. D 76 (2007) 033008, by G.C. Branco, M.N. Rebelo and J.I. Silva-Marcos.

Another important aspect of the origin of CP violation is the question of whether CP is a good symmetry of the Lagrangian, only broken by the vacuum. In the context of Supersymmetric Theories it is a great challenge to construct models where CP is spontaneously broken and yet the CKM matrix is complex. One of the rare examples of such a model was constructed by CFTP members: Spontaneous CP Violation in a SUSY Model with a complex CKM by G.C. Branco, D.Emmanuel-Costa, J.C.Romão, published in Phys. Lett. B 639 (2006) 661.

It is also known that the strength of CP violation in the Standard Model is not sufficient to generate the Baryon Asymmetry of the Universe (BAU). Almost all extensions of the Standard Model including Supersymmetry have new sources of CP violation. The members of CFTP have been actively investigating models with possible additional sources for CP violation and also the generation of (BAU) through leptogenesis. These are some of the present hottest topics in Particle Physics. Click here for an extensive list of papers of CFTP written on CP violation.

One of the best general references on CP violation is the book written by three CFTP members, published in the Oxford International Series of Monographs on Physics, the same series where appeared the famous Dirac Book on Quantum Mechanics: CP Violation, Gustavo C. Branco, Luis Lavoura, Joao P. Silva, International Series of Monographs on Physics, No. 103 Oxford University Press. Oxford, UK: Clarendon (1999) 511 p. (The three CFTP members who authored this Book received The Gulbenkian Science Prize for this work).

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