The basic ingredients of the Spontaneous Symmetry Breaking Phenomenon and of the Higgs Mechanism are reviewed in these lectures of pedagogical character. Some relevant topics related with the breaking SU(2)L ×U(1)Y → U(1)em are selected and discussed here. A brief survey of the experimental Higgs particle searches and the theoretical limits on MH are also presented. The main features of the most popular models of symmetry breaking beyond the Standard Model are briefly considered. It includes a short summary of the Higgs Sector in the Minimal SUSY Model, the basic ideas of Technicolor models and a brief introduction to Strongly Interacting Scalar sectors and to the Effective Chiral Lagrangian Approach to the Electroweak Theory. FTUAM Jan/96/1 hep-ph/9601– January 1996 Lectures given at the XXIII International Meeting On Fundamental Physics, Comillas, Santander, Spain, May 1995 e–mail:herrero@delta.ft.uam.es; herrero@vm1.sdi.uam.es
A short review of the properties of the spin light of neutrino ($SL\nu$) in matter, supplied with some historical notes on the discussed subject, is given. It is shown that consideration of the $SL\nu$ in matter in hep-ph/0605114 is based on erroneous calculations which ignore the fact that the energy-momentum conservation law can not be violated for this process. An attempt to rename the $SL\nu$ in matter, undertaken in hep-ph/0606262, is groundless.
This paper has been withdrawn by the author, because a profoundly overhauled and improved version, also with a new title and two more authors, has now been submitted to the arXiv, with no. hep-ph/0310059. In view of the elapsed time and the very substantial changes in the original paper, a new e-print was judged more appropriate than just a replacement.
A condensed survey of various aspects of LEP 1 physics, e + e − → ff , is presented, with a critical examination of the ingredients that are available for theoretical predictions. A prototype of comparisons for 2f calculations can be found in hep-ph/9902452. 1
We report on recent constraints on models with a flat ``universal'' extra dimension in which all Standard Model fields propagate in the bulk. A significantly improved constraint on the compactification scale is obtained from the extended set of electroweak precision observables accurately measured at LEP1 and LEP2. We find a lower bound of 1/R > 700 (800) GeV at the 99% (95%) confidence level. Comparison of this constraint with the relic density of Kaluza-Klein dark matter for the Minimal UED model points towards the necessity of including non-minimal boundary terms which motivates studying alternative Kaluza-Klein dark matter candidates. Results for the one-loop induced magnetic dipole moment for Kaluza-Klein neutrino dark matter are presented. This talk is based on Phys.Rev.D73:095002,2006 and hep-ph/0601161.
In a recent paper hep-ph/0208225 it has been claimed that to one-loop order in noncommutative phi^4 scalar field theory using dimensional regularization the UV and IR divergencies decouple. We point out that this statement is incorrect.
This paper has been withdrawn by the authors. This paper started with a wrong term describing elastic scattering. The correct form of the kinetic equations for the density matrix are derived e.g. in A. Dolgov, Yad. Fiz. 33 (1981) 1309; K. Enqvist, K. Kainulainen and J. Maalampi, Nucl. Phys. B 349 (1991) 754; G. Sigl and G. Raffelt, Nucl. Phys. B 406 (1993) 423. When using the correct form of the kinetic equations, the result is in good agreement with old results, A. Dolgov and S. Hansen, hep-ph/0009083.
Here I present the effect of gaugino condensation and discrete symmetries to the model-independent axion potential, collaborated with Georgi and Nilles [hep-ph/9805510].
Landshoff and Donnachie [A. Donnachie and P. V. Landshoff, Phys. Lett. B 296, 227 (1992).; P. V. Landshoff, hep-ph/0509240] parametrize the energy behavior of pp and pp scattering cross sections with five parameters, using: {sigma}{sup +}=56.08s{sup -0.4525}+21.70s{sup 0.0808} for pp, {sigma}{sup -}=98.39s{sup -0.4525}+21.70s{sup 0.0808} for pp. Using the four analyticity constraints of Block and Halzen [M. M. Block and F. Halzen, Phys. Rev. D 72, 036006 (2005).], we simultaneously fit the Landshoff-Donnachie form to the same sieved set of pp and pp cross section and {rho} data that Block and Halzen used for a very good fit to a ln{sup 2}s parametrization. We show that the satisfaction of the analyticity constraints will require modification of the Landshoff-Donnachie parametrization for lower energies, thus altering its inherent appeal of simplicity and universality.