Lagrangians for Massive Dirac Chiral Superfields

A variant for the superspin one-half massive superparticle in $4D$, $\mathcal{N}=1$, based on Dirac superfields, is offered. As opposed to the current known models that use spinor chiral superfields, the propagating fields of the supermultiplet are those of the lowest mass dimensions possible: scalar, Dirac and vector fields. Besides the supersymmetric chiral condition, the Dirac superfields are not further constrained, allowing a very straightforward implementation of the path-integral method. The corresponding superpropagators are presented. In addition, an interaction super Yukawa potential, formed by Dirac and scalar chiral superfields, is given in terms of their component fields. The model is first presented for the case of two superspin one-half superparticles related by the charged conjugation operator, but in order to treat the case of neutral superparticles, the Majorana condition on the Dirac superfields is also studied. We compare our proposal with the known models of spinor superfields for the one-half superparticle and show that it is equivalent to them.Comment: 22 pages. Matches published versio

Dynamical seesaw mechanism for Dirac neutrinos

So far we have not been able to establish that, as theoretically expected, neutrinos are their own anti-particles. Here we propose a dynamical way to account for the Dirac nature of neutrinos and the smallness of their mass in terms of a new variant of the seesaw paradigm in which the energy scale of neutrino mass generation could be accessible to the current LHC experiments.Comment: 7 pages, 1 figur

String completion of an SU(3)c⊗SU(3)L⊗U(1)X\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)_X} electroweak model

The extended electroweak $\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)_X}$ symmetry framework "explaining" the number of fermion families is revisited. While $331$-based schemes can not easily be unified within the conventional field theory sense, we show how to do it within an approach based on D-branes and (un)oriented open strings, on Calabi-Yau singularities. We show how the theory can be UV-completed in a quiver setup, free of gauge and string anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos are Dirac-type, and their lightness results from a novel TeV scale seesaw mechanism. Dynamical violation of baryon number by exotic instantons could induce neutron-antineutron oscillations, with proton decay and other dangerous R-parity violating processes strictly forbidden.Comment: 12 pages, 2 figures, published versio

Three-family left-right symmetry with low-scale seesaw mechanism

We suggest a new left-right symmetric model implementing a low-scale seesaw mechanism in which quantum consistency requires three families of fermions. The symmetry breaking route to the Standard Model determines the profile of the "next" expected new physics, characterized either by the simplest left-right gauge symmetry or by the 3-3-1 scenario. The resulting $Z^\prime$ gauge bosons can be probed at the LHC and provide a production portal for the right-handed neutrinos. On the other hand, its flavor changing interactions would affect the K, D and B neutral meson systems.Comment: 10 pages, 2 figures. Revised version as accepted by JHE

The Unbearable Lightness of Being Fronterizo: Reflections on Border Crossing

This essay—a blend of critical commentary with personal memoir—is a report on border crossing, on the ghosts that we carry, on the stories that we bear, and the promise that is handed on in telling them. Our material realities are made up of fragments of memories, echoes and traces that give shape and depth to a place. What happens, however, in the case of border crossers who find themselves suspended in-between the memory of what was left behind with the reality of a different cultural context? Through a reading of border crossings works, this paper examines the spectres/ghosts/echoes/ traces—the oftentimes traumatic residue— that remains when crossing borders. The works I discuss offer up a migratory aesthetics through what I have been calling an “unbearable lightness of being fronterizo.” As a response to narratives of control—hegemonic narratives that attempt to define or inscribe a space—a fronterizo practice can function to undermine reifying narratives, positing a contestatory strategy for emerging cultures

Testing theories of doctoral student persistence at a hispanic serving institution

Lilttle empirical work exists which tests theories of doctoral student persistence. Among these studies, there is limited representation of minority students. To counter this state of affairs, this study uses a sample of four doctoral cohorts enrolled at a Hispanic Serving Institution. Focusing on the earlier stages of graduate study, I adapt theories of persistence previously employed for undergraduate students (Hurtado, 1992; Hurtado & Carter, 1997; Tinto, 1993). Testing the impact of student background characteristics. departmental context, and student social and academic integration on persistence, findings are mixed. Strongest support is found for the effect of academic integration, father\u27s education, age. and being Latina/o. Weak support is found for the effect of departmental characteristics, such as department racial climate