REPRESENTACIONES E IMAGINARIOS SOCIALES EN EL PROCESO MIGRATORIO

The migrant constantly experiences processes of construction of shared meaning where symbolic figures, collective memories, scaffolding and anchoring of thoughts arise; generating, redrawing and transforming what is known as imaginary and social representations. In addition, migration is a phenomenon that responds to human need, such as work, social security, personal growth, among others. Sometimes responds to emergency needs. Migration is the escape from a fate that seems even worse. This phenomenon generates various approaches that give rise to academic debates, where it is of concern how do the representations and the instituted imaginaries of migrants change? Or how do new representations and imaginaries arise in immigrants? How are representations and imaginaries contrasted? To delve into these concerns, a documentary study was carried out with the purpose of deepening the knowledge about representations and social imaginaries in the migratory process. For this, there was a need to review the approaches on representations of Moscovici (2000), Jodelet (1992), Hall (1985); to the ideas about imaginaries of Durkheim (1968), Castoriadis (2003), Durand (1994), Maffesoli (1993) and the ideas about the migratory process of Gómez (2010) and Arango (2003). Finally, imaginaries and representations are understood as useful theoretical tools to question the social order and what is assumed to be established, repainting socially shared beliefs. Also, imaginaries and representations allow tracing forms and mechanisms from which certain meanings become hegemonic and how the dynamic unfolds around disputes, conflicts, agreements and the emergence of meanings, actions, subjectivities and materializations in relation to various social phenomena such as the migratory process.El migrante experimenta constantemente procesos de construcción de sentido compartido donde surgen figuras simbólicas, memorias colectivas, andamiaje y anclaje de pensamientos; generando, redibujando y transformando lo que se conoce como imaginario y representaciones sociales. Además, la migración es un fenómeno que responde a la necesidad humana, como el trabajo, la seguridad social, crecimiento personal, entre otras. A veces responde a necesidades de emergencia. La migración es la escapatoria de una suerte que parece todavía peor. Este fenómeno genera diversos planteamientos que dan lugar a debates académicos, donde inquieta ¿cómo cambian las representaciones y los imaginarios instituidos de los migrantes? O ¿Cómo surgen nuevas representaciones e imaginarios en los inmigrantes? ¿Cómo se contrastan las representaciones y los imaginarios? Para profundizar sobre estas inquietudes se realizó un estudio documental con el propósito de profundizar en el conocimiento sobre representaciones e imaginarios sociales en el proceso migratorio. Para ello, hubo la necesidad de realizar una revisión a los planteamientos sobre representaciones de Moscovici (2000), Jodelet (1992), Hall (1985); a los planteamientos sobre imaginarios de Durkheim (1968), Castoriadis (2003), Durand (1994), Maffesoli (1993) y los planteamientos sobre el proceso migratorio de Gómez (2010) y Arango (2003). Finalmente, se comprenden a los imaginarios y representaciones como herramientas teóricas útiles para cuestionar el orden social y lo que se asume como establecido, repintando las creencias socialmente compartidas. También, los imaginarios y las representaciones, permiten rastrear formas y mecanismos a partir de los cuales ciertas significaciones devienen hegemónicas y cómo se despliega la dinámica en torno a las disputas, conflictos, acuerdos y emergencia de sentidos, acciones, subjetividades y materializaciones en relación a diversos fenómenos sociales como por ejemplo el proceso migratorio. &nbsp

Top-quark FCNC Productions at LHC in Topcolor-assisted Technicolor Model

We evaluate the top-quark FCNC productions induced by the topcolor assisted technicolor (TC2) model at the LHC. These productions proceed respectively through the parton-level processes g g -> t c_bar, c g->t, c g -> t g, c g -> t Z and c g -> t \gamma. We show the dependence of the production rates on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model. We find that for each channel the TC2 model predicts a much larger production rate than the supersymmetric model. All these rare productions in the TC2 model can be enhanced above the 3-sigma sensitivity of the LHC. Since in the minimal supersymmetric model only c g -> t is slightly larger than the corresponding LHC sensitivity, the observation of these processes will favor the TC2 model over the supersymmetric model. In case of unobservation, the LHC can set meaningful constraints on the TC2 parameters.Comment: 5 pages, 4 fig

Higgs Boson Flavor-Changing Neutral Decays into Top Quark in a General Two-Higgs-Doublet Model

Higgs boson decays mediated by flavor changing neutral currents (FCNC) are very much suppressed in the Standard Model, at the level of 10^{-15} for Higgs boson masses of a few hundred GeV. Therefore, any experimental vestige of them would immediately call for new physics. In this paper we consider the FCNC decays of Higgs bosons into a top quark in a general two-Higgs-doublet model (2HDM). The isolated top quark signature, unbalanced by any other heavy particle, should help to identify the potential FCNC events much more than any other final state. We compute the maximum branching ratios and the number of FCNC Higgs boson decay events at the LHC collider at CERN. The most favorable mode for production and subsequent FCNC decay is the lightest CP-even state in the Type II 2HDM, followed by the other CP-even state, if it is not very heavy, whereas the CP-odd mode can never be sufficiently enhanced. Our calculation shows that the branching ratios of the CP-even states may reach 10^{-5}, and that several hundred events could be collected in the highest luminosity runs of the LHC. We also point out some strategies to use these FCNC decays as a handle to discriminate between 2HDM and supersymmetric Higgs bosons.Comment: Minor modifications in the text. Version accepted in Nucl. Phys.

SUSY-Induced Top Quark FCNC Processes at Linear Colliders

In the Minimal Supersymmetric Model (MSSM) the hitherto unconstrained flavor mixing between top-squark and charm-squark will induce the flavor-changing neutral-current (FCNC) interaction between top quark and charm quark, which then give rise to various processes at the next generation linear collider (NLC), i.e., the top-charm associated productions via $e^+ e^-$, $e^- \gamma$ and $\gamma \gamma$ collisions as well as the top quark rare decays $t \to c V$ ($V=g$, $\gamma$ or $Z$). All these processes involve the same part of the parameter space of the MSSM. Through a comparative analysis for all these processes at the NLC, we found the best channel to probe such SUSY-induced top quark FCNC is the top-charm associated production in $\gamma \gamma$ collision, which occurs at a much higher rate than $e^+ e^-$ or $e^- \gamma$ collision and may reach the detectable level for some part of the parameter space. Since the rates predicted by the Standard Model are far below the detectable level, the observation of such FCNC events would be a robust indirect evidence of SUSY.Comment: 12 pages, 8 figures (more refs added, discussions extended

Single top production associated with a neutral scalar at LHC in topcolor-assisted technicolor

The topcolor-assisted technicolor (TC2) model predicts a number of neutral scalars like the top-pion ($\pi^0_t$) and the top-Higgs ($h^0_t$). These scalars have flavor-changing neutral-current (FCNC) top quark couplings, among which the top-charm transition couplings may be sizable. Such FCNC couplings induce single top productions associated with a neutral scalar at the CERN Large Hadron Collider (LHC) through the parton processes $cg \to t \pi_t^0$ and $cg \to t h_t^0$. In this note we examine these productions and find their production rates can exceed the $3\sigma$ sensitivity of the LHC in a large part of parameter space. Since in the Standard Model and the minimal supersymmetric model such rare productions have unobservably small production rates at the LHC, these rare processes will serve as a good probe for the TC2 model.Comment: 7 pages, 3 fig

Single top-quark production by direct supersymmetric flavor-changing neutral-current interactions at the LHC

Production of (electrically neutral) heavy-quark pairs, such as t{\bar c} and {\bar t}c, is extremely suppressed in the SM. In supersymmetric (SUSY) theories, such as the MSSM, the number of these events can be significantly enhanced thanks (mainly) to the FCNC couplings of gluinos. We compute the efficiency of this mechanism for FCNC production of heavy quarks at the LHC. We find that \sigma (pp\to t\bar{c}+\bar{t}c) can reach 1 pb, and therefore one can expect up to 10^{5} events per 100 fb^{-1} of integrated luminosity (with no counterpart in the SM). Their detection would be instant evidence of new physics, and could be a strong indication of underlying SUSY dynamics.Comment: 6 pages, 3 figures. New references and comments added. Invited talk at the 7th International Symposium on Radiative Corrections (RADCOR 2005), Shonan Village, Japan, 200

FCNC-induced heavy-quark events at the LHC from Supersymmetry

We analyze the production and subsequent decay of the neutral Higgs bosons of the MSSM into electrically neutral quark pairs qq'=bs,tc of different flavors at the LHC and compare with the direct FCNC production mechanisms. The cross-sections are computed in the unconstrained MSSM with minimal flavor-mixing sources and taking into account the stringent bounds from radiative B-meson decays. We extend the results previously found for these FCNC processes, which are singularly uncommon in the SM. Specifically, we report here on the SUSY-EW contribution of the Higgs-mediated FCNC cross-section into bs and tc final states and the SUSY-QCD and SUSY-EW contributions to bs-production. In this way, the complete map of MSSM predictions for the qq'-pairs produced at the LHC becomes available. The upshot is that the most favorable channels are: 1) the Higgs boson FCNC decays into bs, and 2) the direct production of tc pairs, both of them at the 1 pb level and mediated by SUSY-QCD effects. If, however, the latter are suppressed, we find a small SUSY-EW yield for the tc-production through Higgs decays but, at the same time, a cross-section of 0.1-1 pb for bs-production, which implies a significant number (10^4-10^5) of bs-pairs per 100 inverse femtobarn of integrated luminosity.Comment: LaTeX, 17 pages, 4 figures, 4 tables. Extended discussion. Accepted in Phys. Lett.

CP-odd invariants in models with several Higgs doublets

We present CP-odd Higgs-basis invariants, which can be used to signal CP violation in a multi-Higgs system, written in an arbitrary Higgs basis. It is shown through specific examples how these CP-odd invariants can also be useful to determine the character of CP breaking (i.e. whether it is hard or soft CP breaking) in a given Higgs Lagrangian. We analyse in detail the cases of two and three Higgs doublets

Search for t->ch at e+e- Linear Colliders

We study the rare top-quark decay t->ch, where h is a generic Higgs boson, at a linear collider. If kinematically accessible, all models contain this decay at some level due to quark flavor mixing. Some models, such as Model III of the two-Higgs doublet model, have a tree-level top-charm-Higgs coupling, and the branching ratio is close to 0.5%. Others, such as the MSSM, have a coupling induced at one-loop, and can have a branching ratio in the range of 10^{-5} - 5x10^{-4}. We find that a linear collider of root(s) = 500 GeV and a luminosity of 500 fb^{-1} will begin to be sensitive to this range of the coupling.Comment: 12 pages, 5 figures, 2 table