Light charged Higgs boson production at the Large Hadron electron Collider

We study the production of a light charged Higgs boson at the future Large Hadron electron Collider (LHeC), through the process $e^- p \to \nu_e H^- q$ considering both decay channels $H^- \to b \bar c$ and $H^- \to \tau \bar \nu_\tau$ in the final state. We analyse these processes in the context of the 2-Higgs Doublet Model Type III (2HDM-III) and assess the LHeC sensitivity to such $H^-$ signals against a variety of both reducible and irreducible backgrounds. We confirm that prospects for $H^-$ detection in the 2HDM-III are excellent assuming standard collider energy and luminosity conditions.Comment: 12 pages, 12 figures. Accepted in Physical Review

The influence of massive stars in the interstellar medium of IC 1613: the supernova remnant S8 and the nebula S3 associated with a WO star

We present a detailed kinematical analysis of two selected nebulae in the Local Group irregular galaxy IC 1613. The nebulae are: S8, the only known supernova remnant in this galaxy, and S3, a Wolf-Rayet nebula associated with the only WO star in this galaxy. For S8, we have obtained and analyzed its radial velocity field, where we found complex profiles which can be fitted by several velocity components. These profiles also show the presence of high velocity, low density gas. From this, we have obtained the expansion velocity, estimated the preshock density and calculated the basic kinematical parameters of this SNR. We suggest that in S8 we are seing a SNR partially hidden by dust. This suggestion comes from the fact that the SNR is located between two superbubbles where a ridge of obscured material unveils the existence of dust. Moreover, we show that this hypothesis prevails when energetic arguments are taken into account. In the case of S3, this nebula shows bipolar structure. By means of its kinematics, we have analyzed its two lobes, the ``waist'', as well as its relation with the nearest superbubbles. For the first time we are able to see closed the NW lobe, showing a clover leaf shape. This fact allows a better quantitative knowledge of the nebula as a whole. Furthermore, we found evidence of an expansion motion in the NW lobe. In the light of our results, we can express that these nebulae are the product of very massive stellar evolution. It is surprising the influence these stars still have in shaping their surrounding gas, and on the energy liberation towards the interstellar medium of this galaxy.Comment: Accepted for publication in the Astronomical Journal, July issue. 11 pages, 12 figures. High resolution figures can be found at http://www.inaoep.mx/~mago/PAPERS/AJ

Superbubble evolution including the star-forming clouds: Is it possible to reconcile LMC observations with model predictions?

Here we present a possible solution to the apparent discrepancy between the observed properties of LMC bubbles and the standard, constant density bubble model. A two-dimensional model of a wind-driven bubble expanding from a flattened giant molecular cloud is examined. We conclude that the expansion velocities derived from spherically symmetric models are not always applicable to elongated young bubbles seen almost face-on due to the LMC orientation. In addition, an observational test to differentiate between spherical and elongated bubbles seen face-on is discussed.Comment: 25 pages, 7 figures, accepted to ApJ (September, 1999 issue