ELEMENTARY PARTICLES

Author: ROTA FONT FRANCESC.
Year: 2004.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: ESCUELA DE POSTGRADO.

Summary: The vision that is now the universe is based on the cosmological model of Friedmann-Robertson-Walker (FRW), commonly known as the Big Bang model. This model considers that in the beginning the universe was a very high-energy plasma which has been expanding and cooling down to the present day, leading to different phase transitions that have led to the universe to its present state. Over the past 15 years, the comments have helped prove this model with a high precision, reaching a splendid confirmation. Besides based on the theory of general relativity, the other linchpin of the FRW model is the standard model of elementary particles. This model, which describes the interactions between elementary particles known so far, it has been confirmed experimentally with great precision in the range of energies accessible in terrestrial experiments. Still, we know that this model of elementary particles is an effective theory is not valid when we go to higher energies, inaccessible so far in laboratory experiments land. For eslo, that the study of the early universe, where the typical energies are much higher than those available from the earth, we can give information on new or new particle interactions. The primordial nucleosynthesis is one of the theoretical predictions which has given a resounding confirmation of the model Bing bang. Its success is based on the prediction of the amount of light nuclei produced in the early universe, that amount today can measure giving a confirmation to the theoretical model, as well as information important cosmological parameters. The nucleosynthesis primoridal is based on the interaction of photons, electrons, positrons, neutrinos, protons and neutrons in the framework of an expanding universe. As the universe is expanding, the balance between these interactions is breaking leading to the formation of nuclei lighter. The expansion of the universe is described by the equation Friedmann, one of the key figures in the FRW model. Any amendment to alter this equation the expansion of the universe and changing predictions standards nucleosynthesis paramount. In this thesis provides a quantitative study of what is the scope for modifying the equation allowing Friedman comments. Acotando any deviation from the standard Friedmann equation can limit the possible new physics that might be relevant at the moment that occurs when primordial nucleosynthesis. As implementation is narrowing different models where the gravity is coupled so fistinta matter and antimatter and the various families leptónicas. It is important to note that the time of nucleosynthesis primoridal is the oldest in the history of the universe from which it is observational evidence. As previously discussed, one of the major challenges of theoretical physics today is to find extensions to the standard model of elementary particles. These extensions can be in the form of new interactions as well as the presence of new particles, undetected so far. One of the paradigmatic examples of new particle is the case of axión. This particle appears as a result of the theoretical solution to the problem of CP violation in interracciones strong. More explicitly, this particle is bosón of Goldstone that appears after the spontaneous rupture of the symmetry of Peccei-Quinn (PQ). This rupture occurs at very high energies, so the axión is a particle which occurs mainly in the early universe. There are different mechanisms of production axiones, with one producing heat through reactions with the particulate matter in the early universe. In this thesis is reanalizan the co 8 ndicione 7af s under which there is production thermal axiones, giving new heights with the parameters relevant to the physics of axiones and new predictions for the density axiones thermal currently present in the universe. Currently it is known that the universe is composed of a 0.5% of the area that emits light (and therefore, we can observe), a 30% dark matter and the rest is in the form of energy. In the dark matter, only 5% of it is known that is formed by particles we know. The remaining 90% would be composed of particles that have not yet been detected (dark matter not bariónica). One of the most attractive features of axión is possible that it is one of the constituents of dark matter not bariónica. However, there are theoretical reasons to believe that in the early universe have been having similar to the symmetries of PQ currently broken and therefore have led to scalar particles similar to axión, but with a different physical. As an input end of this thesis is a comprehensive study of the possibility that dark matter is not bariónica formed by the Goldstone bosons which have adquiridio mass quantum effects of gravity.

Author: CATÁ CONTRERAS OSCAR.
Year: 2004.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: ESCUELA DE POSTGRADO.

Author: GARCÍA CASCALES JUAN FRANCISCO.
Year: 2004.
University: AUTÓNOMA DE MADRID [www.uam.es].
Place of defense: DEPARTEMENTO DE FÍSICA TEÓRICA.
Place of preparation: DEPARTAMENTO DE FÍSICA TEÓRICA Y INSTITUTO DE FÍSICA TEÓRICA UAM-CSIC..

Summary: In this thesis we have presented the rules of consistency for the construction of models in the field of String Theory, which combines the presence of D-branas with a background flow cord closed. The resulting models, and contain a group of symmetry and chiral particle spectrum very similar to those of Nature, presents many advantages from the point of view phenomenological, stabilizing most of the scalar fields without mass (customary in other compactificaciones less sophisticated), the emergence of a large metric factor "redshift" gravitational or the possibility of breaking supersymmetry in a realistic manner and controlled.

Author: LÓPEZ ALBACETE JAVIER.
Year: 2004.
University: GRANADA [www.ugr.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Author: MANJARIN COLON JUAN JOSE.
Year: 2004.
University: AUTÓNOMA DE MADRID [www.uam.es].
Place of defense: DEPARTAMENTO DE FISICA TEORICA.
Place of preparation: INSTITUTO DE FISICA TEORICA IFT/UAM/CSIC.

Summary: The objective of this thesis is focused on the role of teoría-K a cohomología widespread in the classification of the soliton that appear on String Theory, as well as extract information about the structure gauge behind them. The starting point is the apparent contradiction between the description in terms of SUGRA and teoría-K of D6-brana: whereas in the first case is seen as a monopolo abeliano, the second is no-abeliano. The extra degrees of freedom needed to make a unified description appear to include the effects of campo-B, which belongs to the spectrum without mass sector closed and can be seen as a generator of electric charge. The most important point is that these electrical degrees of freedom may be associated with the existence of a theory in 11 dimensions, the call teoría-M. On the other hand, full description of the effects of campo-B leads in the latter part of the thesis to check that the industry theory of topological type IIA may be associated with a structure gauge type heterótico, ie with a group E (8), more specifically its task bonds issued centrally, as both free basis point, where the extension center can be seen as the mass of Romans of SUGRA mass.

Author: ALVAREZ EZEQUIEL.
Year: 2005.
University: VALENCIA [www.uv.es].
Place of defense: FACULTAD DE FISICA.
Place of preparation: FACULTAD DE FÍSICA.

Summary: In this paper we study the symmetries T, CP and CPT in the system Inns B. Our analysis and results entán directed to the case of correlated inns in factories Inns B. In the first set of theory and results investigate the consequences of these simetrícas in mixing B's and the interference between mixing and decay. With the help of the tag by CP cp-tag calculate all possible strengths and asimetrícas concerning sabor-especifíco and decay COP Golden Plate. Our observed proposed are a new verification auto-consistencia for Standard, as well as a new exploration for traces of discrete symmetries in the system Inns B. The second set of outcomes studied violation of CPT in the initial state of fabrícas Ba through the loss of insistinguibilidad of by bb. We show that if you relax the requirement estad/1stica of Bose, then events dileptónicos equal sign are considerably modified. In order to analyze tag for flavor (demise of flavour-tag), and also tested that the asymmetry load Event mismo-signo A sl is an observable optimal where neva find this kind of violation of CPT. The detailed study of this asymmetry allows us to predict different behaviors agreement withthe possible parameter values of CPT violation, wi We conclude that the best observable to find traces of this brand-new kind of violation of CPT is the analysis of A_sl a short time. We also use existing A_sl to put limits in the first wi

Author: ROJO CHACÓN JUAN.
Year: 2005.
University: BARCELONA [www.ub.es].
Place of defense: FACULTAT DE FÍSICA.
Place of preparation: FACULTAT DE FÍSICA, UNIVERSITAT DE BARCELONA.

Author: HIDALGO REVILLA IRENE.
Year: 2005.
University: AUTÓNOMA DE MADRID [www.uam.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD CIENCIAS.

Summary: This thesis focuses on the problem of hierarchies of Standard Model of particles and the naturalness of electroweak symmetry breaking into concrete scenarios physics beyond the Standard Model. The problem with hierarchies gives an estimate of the scale where it is expected to find new physics, based on the sensitivity of the mass of the Higgs to quadratic divergences. If we impose the mass of the Higgs is not subject to a fine adjustment or fine-tuning will get an estimate on the scale with an upper approximately 2-3 TeV probably accessible to the LHC experiment. The general analysis is presented in this thesis based on the study of potential cash to a separate loop of the model shows that the estimated peak height works well as a conservative, as they have been ignored other contributions to the mass of the Higgs that can be potentially large. To be more specific, the analysis of fine adjustment should be made in specific settings of new physics to get more precise implications of the arguments of naturalness. Therefore, have been analyzed different examples of new physics: massive neutrino masses generated by the mechanisms seesaw models superimétricos and models from Little Higgs. In the case of neutrino seesaw we have concluded that presents a problem of fine-tuning that can not be improved unless it is introduced additional new physics. For models supersimétricos were found cases where you can put the limit 2-3 TeV encountered naturalness arguments in the Standard Model and usually for these models are not fine-tuneados are expected to find new particles supersimétrica at the upcoming the TeV. In addition, the supersymmetry models have been considered Little Higgs, and has compared the analysis of fine-tuning them with the models supersimétricos analyzed and it has been shown that the models of Little Higgs presents a lot of fine-tuning because of the complex internal structure of these models and the many adjustments "hidden" offered. These tests give us a criterion of naturalness for different kinds of scenarios and in conjunction with measures of precision electroweak give us a guide on the properties of the new physics and scales where we hope to find this new physics.

Author: GARCÍA ÁLVAREZ DAVID.
Year: 2006.
University: ZARAGOZA [www.unizar.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: An analysis of the emergence of non-analytical terms and singularities in the action effectively dimensional gauge theories, and their dependence on the regularization scheme used, it appears that the so-called anomaly parity can be canceled. This gives the phenomenon an analogy with the effect of spontaneous rupture, rather than a genuine anomaly. Analysis of the ambigà ¼ ages existing theories pure gauge not abelianas suggests a new mechanism for generating mass. The values of the mass obtained by this mechanism are in agreement with those obtained by numerical simulations in retículo and those of Nair and Karabali methods Hamiltonianos. On the other hand, in an attempt to describe the dynamics of particles with no mass and helicity three, we boarded the analysis of two alternative descriptions of the dynamics of gauge fields associated with connections simplécticas. Both have a number of interesting phenomena, such as the existence of a vacuum theta similar to Cromodinámica Quantum. The first theory is natural from the point of view geometric, but does not describe a theory of relativistic invariant fields. The second theory describes the dynamics of particles of spin three interacting with each other and with the gravitational field. Corrections radioactive generate a mass term for a rate mechanism Coleman-Weinberg, showing explicitly how it is not possible to evade the restrictions imposed by theorems not go to the theories of spins higher than two. Calculating the radiative corrections of the new theory, it is noted that many acoplos the terms of autointeracción of three camps spin become irrelevant, but this is not sufficiently illuminated the search for a theory with less simplest terms of interaction. In any case, the theory introduced in this report describes the interaction of spin three camps only with itself and the gravitational field, since it does not support the interaction of these fields relevant form with any other field of Standard Model, which makes them excellent candidates to solve the problem of dark matter in the Universe.