Electroweak precision measurements in supersymmetric models with a U(1)R lepton number

As experimental constraints on the parameter space of the MSSM and close variations thereof become stronger, the motivation to explore supersymmetric models that challenge some of the standard assumptions of the MSSM also become stronger. For example, models where the gauginos are Dirac instead of Majorana have recently received more attention. Beside allowing for a supersoft SUSY breaking mechanism where the gauginos only provide finite threshold corrections to scalar masses, the cross section for the production of a squark pairs is reduced. In addition, Dirac gauginos can be used to build models that possess a U(1)R symmetry. This symmetry can then be identified with a lepton number, leading to models that are quite different from conventional scenarios. The sneutrinos in these models can acquire a vev and give mass to the leptons and the down-type squark. The phenomenology is novel, combining signatures that are typical of R-parity violating scenarios with signatures arising from leptoquarks. Correspondingly the constraints from electroweak precision data are also different. In these models, one of the leptons mixes with gauginos and superpotential Yukawa couplings can contribute to EWPM at tree level. In addition, lepton universality is broken. In this paper we adapt the operators analysis of Han and Skiba [1] to include the relevant violation of lepton universality, and do a global fit of the model to electroweak precision data, including all relevant tree-level and loop-level effects. We obtain bounds on the vev of the sneutrino and on the superpotential couplings of the model.Comment: 18 pages, 6 figures, references adde

The spontaneous Z2\mathbb{Z}_2 breaking Twin Higgs

The Twin Higgs model seeks to address the little hierarchy problem by making the Higgs a pseudo-Goldstone of a global $SU(4)$ symmetry that is spontaneously broken to $SU(3)$. Gauge and Yukawa couplings, which explicitly break $SU(4)$, enjoy a discrete $\mathbb{Z}_2$ symmetry that accidentally maintains $SU(4)$ at the quadratic level and therefore keeps the Higgs light. Contrary to most beyond the Standard Model theories, the quadratically divergent corrections to the Higgs mass are cancelled by a mirror sector, which is uncharged under the Standard Model groups. However, the Twin Higgs with an exact $\mathbb{Z}_2$ symmetry leads to equal vevs in the Standard Model and mirror sectors, which is phenomenologically unviable. An explicit $\mathbb{Z}_2$ breaking potential must then be introduced and tuned against the $SU(4)$ breaking terms to produce a hierarchy of vevs between the two sectors. This leads to a moderate but non-negligible tuning. We propose a model to alleviate this tuning, without the need for an explicit $\mathbb{Z}_2$ breaking sector. The model consists of two $SU(4)$ fundamental Higgses, one whose vacuum preserves $\mathbb{Z}_2$ and one whose vacuum breaks it. As the interactions between the two Higgses are turned on, the $\mathbb{Z}_2$ breaking is transmitted from the broken to the unbroken sector and a small hierarchy of vevs is naturally produced. The presence of an effective tadpole and feedback between the two Higgses lead to a sizable improvement of the tuning. The resulting Higgs boson is naturally very Standard Model like.Comment: 17 pages, 6 figures, references update

LHC constraints on Mini-Split anomaly and gauge mediation and prospects for LHC 14 and a future 100 TeV pp collider

Stringent experimental constraints have raised the lower limit on the masses of squarks to TeV levels, while compatibility with the mass of the Higgs boson provides an upper limit. This two-sided bound has lead to the emergence of Mini-Split theories where gauginos are not far removed from the electroweak scale while scalars are somewhat heavier. This small hierarchy modifies the spectrum of standard anomaly and gauge mediation, leading to Mini-Split deflected anomaly and gauge mediation models. In this paper, we study LHC constraints on these models and their prospects at LHC 14 and a 100 TeV collider. Current constraints on their parameter space come from ATLAS and CMS supersymmetry searches, the known mass of the Higgs boson, and the absence of a color-breaking vacuum. Prospects at LHC 14 and a 100 TeV collider are obtained from these same theoretical constraints in conjunction with background estimates. As would be expected from renormalization group effects, a slightly lighter third generation of squarks is assumed. Higgsinos have masses similar to those of the scalars and are at the origin of the deflection.Comment: 25 pages, 10 figures, references added, LHC 14 results added, matched to journal versio

Aberdeen University Ontology Reuse Stack

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Le Bois Pargas, à Pageas (Haute-Vienne) : un nouveau témoin du Néolithique final en Limousin.

International audienceNear to the village of Pageas, in Haute-Vienne (Limousin, France), the archaeological site of the "Bois Pargas" was discovered after the violent storms of the end of the year 1999, by the finding of artefacts into the stump of a reversed chestnut tree. A small excavation bring to the fore that the tree grew on a Neolithic pit. Although no organic remains are preserved, the archaeological artefacts let us interpret the structure as a pseudo megalithic monument. The funerary pit contained six Pressignian flint daggers, along with arrowheads, "scies à coches", ceramics and some ornaments. All theses artefacts are typical of the IIIrd millennium BC and the technological analysis of the daggers discriminates two times of production which brings to discuss the duration of use of the burial.Le gisement du Bois Pargas, situé sur la commune de Pageas en Haute-Vienne, fut identifié à la suite des violentes tempêtes de la fin de l'année 1999, par la découverte de matériel archéologique pris dans une souche de châtaigner renversé. La réalisation d'un sondage permit de montrer que cet arbre s'était enraciné sur une fosse préhistorique. Bien qu'aucun vestige organique n'ait été conservé, le type de matériel archéologique découvert permet d'interpréter cette structure comme le témoin d'un monument funéraire pseudo-mégalithique. La fosse sépulcrale contenait en effet un ensemble de six poignards en silex du Grand-Pressigny, associés à des pointes de flèches, des scies à coches, de la céramique et des éléments de parure. Ce matériel permet de situer le gisement au IIIe millénaire avant notre ère, et l'analyse technologique des poignards met en évidence deux époques de production qui conduisent à s'interroger sur la durée de fonctionnement de la structure funéraire

On the "generalized Generalized Langevin Equation"

In molecular dynamics simulations and single molecule experiments, observables are usually measured along dynamic trajectories and then averaged over an ensemble ("bundle") of trajectories. Under stationary conditions, the time-evolution of such averages is described by the generalized Langevin equation. In contrast, if the dynamics is not stationary, it is not a priori clear which form the equation of motion for an averaged observable has. We employ the formalism of time-dependent projection operator techniques to derive the equation of motion for a non-equilibrium trajectory-averaged observable as well as for its non-stationary auto-correlation function. The equation is similar in structure to the generalized Langevin equation, but exhibits a time-dependent memory kernel as well as a fluctuating force that implicitly depends on the initial conditions of the process. We also derive a relation between this memory kernel and the autocorrelation function of the fluctuating force that has a structure similar to a fluctuation-dissipation relation. In addition, we show how the choice of the projection operator allows to relate the Taylor expansion of the memory kernel to data that is accessible in MD simulations and experiments, thus allowing to construct the equation of motion. As a numerical example, the procedure is applied to Brownian motion initialized in non-equilibrium conditions, and is shown to be consistent with direct measurements from simulations

A GRASP FOR REAL LIFE INVENTORY ROUTING PROBLEM: APPLICATION TO BULK GAS DISTRIBUTION

International audienc