Associated production of light gravitinos in e^+e^- and e^-\gamma collisions

Light gravitino productions in association with a neutralino (selectron) in e^+e^- (e^-\gamma) collisions are restudied in a scenario that the lightest supersymmetric particle is a gravitino and the produced neutralino (selectron) promptly decays into a photon (electron) and a gravitino. We explicitly give the helicity amplitudes for the production processes by using the effective goldstino interaction Lagrangian, and present the cross sections with different collision energies and mass spectra. We also examine selection efficiencies by kinematical cuts and beam polarizations for the signal and background processes, and show that the energy and angular distributions of the photon (electron) can explore the mass of the t-channel exchange particle as well as the mass of the decaying particle at a future e^+e^- (e^-\gamma) collider.Comment: 12 pages, 12 figures, 4 tables; references added, version to appear in EPJ

On the collisional disalignment of dust grains in illuminated and shaded regions of IC 63

Interstellar dust grain alignment causes polarization from UV to mm wavelengths, allowing the study of the geometry and strength of the magnetic field. Over the last couple of decades, observations and theory have led to the establishment of the radiative alignment torque mechanism as a leading candidate to explain the effect. With a quantitatively well constrained theory, polarization can be used not only to study the interstellar magnetic field, but also the dust and other environmental parameters. Photodissociation regions, with their intense, anisotropic radiation fields, consequent rapid H2 formation, and high spatial density-contrast provide a rich environment for such studies. Here we discuss an expanded optical, NIR, and mm-wave study of the IC 63 nebula, showing strong H2 formation-enhanced alignment and the first direct empirical evidence for disalignment due to gas-grain collisions using high-resolution HCO+(J = 1-0) observations. We find that a relative amount of polarization is marginally anticorrelated with column density of HCO+. However, separating the lines of sight of optical polarimetry into those behind, or in front of, a dense clump as seen from γ Cas, the distribution separates into two well defined sets, with data corresponding to "shaded" gas having a shallower slope. This is expected if the decrease in polarization is caused by collisions since collisional disalignment rate is proportional to RC∝nT" role="presentation">RC∝nT−−√ . Ratios of the best-fit slopes for the "illuminated" and "shaded" samples of lines of sight agrees, within the uncertainties, with the square root of the two-temperature H2 excitation in the nebula seen by Thi et al.Fil: Soam, Archana. Sofia Science Center; Estados UnidosFil: Anderson, B. G. Sofia Science Center; Estados UnidosFil: Acosta Pulido, Jose. Instituto de Astrofisica de Canarias; EspañaFil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Vaillancourt, J. E.. Lincoln Laboratory; Estados UnidosFil: Widicus Weaver, S. L.. Department Of Chemistry; Estados UnidosFil: Piirola, V.. University Of Turku; FinlandiaFil: Gordon, M. S.. Sofia Science Center; Estados Unido

Strangeness, Charm and Beauty in Quark Matter: SQM 2007 Experimental Overview

This paper aims at providing an experimental overview of the Strangeness in Quark Matter 2007 ConferenceComment: Proceedings of Strangeness in Quark Matter 2007, submitted to Journal of Physics

Feminist Pedagogy in the STEM Research Laboratory: an Intersectional Approach

The research laboratory is a crucial and indispensable classroom for STEM education. It is where we practice science as a craft and test the ideas that awaken our curiosity, allowing us to create knowledge. It is also a space where challenges await and struggles are imminent. Thus, supporting mentees through their traineeship in a research lab requires an intersectional approach and lens to provide equitable mentorship and guidance. The concept of intersectionality, initially devised by Black feminist professor Kimberlé W. Crenshaw, can be employed to generate practices and frameworks that democratize laboratory culture and provide trainees with a space in which they shape the laboratory culture while helping them recognize their positionality. This critical commentary provides insights and experiences when incorporating feminist frameworks to sustain equitable working environments in the research lab setting, specifically in leading a research group composed predominantly of Puerto Rican women

Higgs decay with monophoton + MET signature from low scale supersymmetry breaking

We study the decay of a standard model-like Higgs boson into a gravitino and a neutralino, which subsequently decays promptly into another gravitino and a photon. Such a decay can be important in scenarios where the supersymmetry breaking scale is of the order of a few TeV, and in the region of low transverse momenta of the photon, it may provide the dominant contribution to the final state with a photon and two gravitinos. We estimate the relevant standard model backgrounds and the prospects for discovering this Higgs decay through a photon and missing transverse energy signal at the LHC in terms of a simplified model. We also give an explicit model with manifest, but spontaneously broken, supersymmetry in which the usual MSSM soft terms are promoted to supersymmetric operators involving a dynamical goldstino supermultiplet. This model can give rise to a SM-like CP-even neutral Higgs particle with a mass of 125 GeV, without requiring substantial radiative corrections, and with couplings sufficiently large for a signal discovery through the above mentioned Higgs decay channel with the upcoming data from the LHC.Comment: 28 pages, 5 figures, 4 tables; v2: updated to JHEP version, references adde

Hospitalización por trastornos mentales y consumo de sustancias en adolescentes argentinos. 2005-2006

Objetivo: Determinar la prevalencia de trastornos mentales y del comportamiento como causa de hospitalización en la población adolescente de 10 a 19 años en Argentina en el período 2005 -2006. Metodología: estudio observacional, analítico y transversal, se utilizaron las Bases de Datos de los Informes Estadísticos de Egresos Hospitalarios (IEH) de la Dirección de Estadística e Información de Salud del Ministerio de Salud de la Nación, años 2005-2006. Los datos fueron analizados según sexo, edad y causa de egreso hospitalario. El procesamiento estadístico de los datos consistió en test de chi–cuadrado, Mantel Haenzel o test de Fisher, p<0,05. Resultados: el 2% de los egresos hospitalarios fueron por Trastornos Mentales y del Comportamiento (TMyC). Los TMyC de mayor frecuencia para el grupo de 10-14 años fueron: trastornos neuróticos (29,89%), consumo de sustancias (23,49%) (p<0,001) y trastornos del comportamiento de inicio en la infancia (15,40%) y para el grupo de 15-19 años fueron: consumo de sustancias (30,94%) (p<0,001), alcohol la más frecuente, trastornos neuróticos (21,04%) y esquizofrenia (17,34%) (p<0,001). La distribución por sexos y edad mostró al consumo de sustancias (p< 0,0001) como la patología más frecuente en varones y trastornos neuróticos (p< 0,0001) en mujeres de ambos grupos de edad. Conclusión: los TMyC son un motivo de hospitalización que aumenta con la edad de los adolescentes y mostró un comportamiento diferenciado por sexo. El consumo de sustancias psicoactivas y los trastornos del comportamiento fueron más frecuentes en los varones y los trastornos neuróticos en las mujeres

Probing R-parity violating models of neutrino mass at the Tevatron via top Squark decays

We have estimated the limiting branching ratio of the R-parity violating (RPV) decay of the lighter top squark, \tilde t_1 \ar l^+ d ($l=e$ or $\mu$ and d is a down type quark of any flavor), as a function of top squark mass(\MST) for an observable signal in the di-lepton plus di-jet channel at the Tevatron RUN-II experiment with 2 fb$^{-1}$ luminosity. Our simulations indicate that the lepton number violating nature of the underlying decay dynamics can be confirmed via the reconstruction of \MST. The above decay is interesting in the context of RPV models of neutrino mass where the RPV couplings ($\lambda'_{i3j}$) driving the above decay are constrained to be small (\lsim 10^{-3} - 10^{-4} ). If $\tilde t_1$ is the next lightest super particle - a theoretically well motivated scenario - then the RPV decay can naturally compete with the R-parity conserving (RPC) modes which also have suppressed widths. The model independent limiting BR can delineate the parameter space in specific supersymmetric models, where the dominating RPV decay is observable and predict the minimum magnitude of the RPV coupling that will be sensitive to Run-II data. We have found it to be in the same ballpark value required by models of neutrino mass, for a wide range of \MST. A comprehensive future strategy for linking top squark decays with models of neutrino mass is sketched.Comment: 28 pages, 14 Figure