Alexandre Arbey

Implications of a 125 GeV Higgs for supersymmetric models

Abstract Preliminary results of the search for a Standard Model like Higgs boson at the LHC with 5 fb−1 data have just been presented by the ATLAS and CMS Collaborations and an excess of events at a mass of ≈ 125 GeV has been reported. If this excess of events is confirmed by further searches with more data, it will have extremely important consequences in the context of supersymmetric extensions of the Standard Model and, in particular the minimal one, the MSSM. We show that for a standard-like Higgs boson with a mass 123 M h 127 GeV , several unconstrained or constrained (i.e. with soft supersymmetry-breaking parameters unified at the high scale) MSSM scenarios would be excluded, while the parameters of some other scenarios would be severely restricted. Examples of constrained MSSM scenarios which would be disfavoured as they predict a too light Higgs particle are the minimal anomaly and gauge mediated supersymmetry-breaking models. The gravity mediated constrained MSSM would still be viable, provided the scalar top quarks are heavy and their trilinear coupling large. Significant areas of the parameter space of models with heavy supersymmetric particles, such as split or high-scale supersymmetry, could also be excluded as, in turn, they generally predict a too heavy Higgs particle.

The Higgs sector of the phenomenological MSSM in the light of the Higgs boson discovery

A bstractThe long awaited discovery of a new light scalar boson at the LHC opens up a new era of studies of the Higgs sector in the Standard Model and in its extensions. In this paper we discuss the consequences of the observation of a light Higgs boson with the mass and rates reported by the ATLAS and CMS collaborations on the parameter space of the phenomenological MSSM, accounting also for the LHC searches for heavier Higgs bosons and supersymmetric particle partners, as well as constraints from B-physics and dark matter. We explore the various regimes of the MSSM Higgs sector, depending on the parameters MA and tan β, and show that only two of them are still allowed by all present experimental constraints: the decoupling regime, in which there is only one light and standard-like Higgs boson while the heavier Higgs states decouple from gauge bosons, and the supersymmetric regime, in which there are light supersymmetric particle partners which might affect the decay properties of the light Higgs boson, in particular its di-photon and invisible decays.

Simplified models for dark matter searches at the LHC

This document outlines a set of simplified models for dark matter and its interactions with Standard Model particles. It is intended to summarize the main characteristics that these simplified models have when applied to dark matter searches at the LHC, and to provide a number of useful expressions for reference. The list of models includes both s-channel and t-channel scenarios. For s-channel, spin-0 and spin-1 mediation is discussed, and also realizations where the Higgs particle provides a portal between the dark and visible sectors. The guiding principles underpinning the proposed simplified models are spelled out, and some suggestions for implementation are presented.

An update of the constraints on the phenomenological MSSM from the new LHC Higgs results

Updated results on the search of Higgs bosons at the LHC with up to 17 fb 1 of data have just been presented by the ATLAS and CMS collaborations. New constraints are provided by the LHCb and XENON experiments with the observation of the rare decay Bs! + and new limits on dark matter direct detection. In this paper, we update and extend the results on the implications of these data on the phenomenological Minimal Supersymmetric extension of the Standard Model (pMSSM) by using high statistics, at scans of its 19 parameters. The new LHC data on b b and decays of the lightest Higgs state and the new CMS limits from the searches for the heavier Higgs states set stronger constraints on the pMSSM parameter space.

Light Neutralino Dark Matter in the pMSSM: Implications of LEP, LHC and Dark Matter Searches on SUSY Particle Spectra

Three dark matter direct detection experiments have reported possible signals which can be interpreted as due to the interaction of light WIMPs with large scattering cross section. In this paper we investigate the viability of SUSY scenarios with light neutralino using high statistics scans in the pMSSM. We identify several scenarios which give rise to very light neutralinos with large direct detection scattering cross sections. We apply constraints from dark matter relic density, direct detection, indirect detection, as well as flavour physics, electroweak precision tests, LEP and Tevatron limits, LHC limits on SUSY, Higgs and monojet searches. In particular we require the Higgs boson mass to be in the range 122.5<Mh<127.5 GeV. We study how the combination of these constraints largely reduces the number of viable scenarios. MSSM solutions with a light neutralino and an almost degenerate lightest scalar bottom quark emerge as the scenario in agreement with all these constraints. We study their characteristics in relation to the LHC missing ET searches.

Supersymmetric heavy Higgs bosons at the LHC

The search for heavy Higgs bosons is an essential step in the exploration of the Higgs sector and in probing the Supersymmetric parameter space. This paper discusses the constraints on the M(A) and tan beta parameters derived from the bounds on the different decay channels of the neutral H and A bosons accessible at the LHC, in the framework of the phenomenological MSSM. The implications from the present LHC results and the expected sensitivity of the 14 TeV data are discussed in terms of the coverage of the [M(A) - tan beta] plane. New channels becoming important at 13 and 14 TeV for low values of tan beta are characterised in terms of their kinematics and the reconstruction strategies. The effect of QCD systematics, SUSY loop effects and decays into pairs of SUSY particles on these constraints are discussed in details.

Supersymmetry with light dark matter confronting the recent CDMS and LHC results

We revisit MSSM scenarios with light neutralino as a dark matter candidate in view of the latest LHC and dark matter direct and indirect detection experiments. We show that scenarios with a very light neutralino (~ 10 GeV) and a scalar bottom quark close in mass, can satisfy all the available constraints from LEP, Tevatron, LHC, flavour and low energy experiments and provide solutions in agreement with the bulk of dark matter direct detection experiments, and in particular with the recent CDMS results.

Status of the charged Higgs boson in two Higgs doublet models

The existence of charged Higgs boson(s) is inevitable in models with two (or more) Higgs doublets. Hence, their discovery would constitute unambiguous evidence for new physics beyond the Standard Model (SM). Taking into account all relevant results from direct charged and neutral Higgs boson searches at LEP and the LHC, as well as the most recent constraints from flavour physics, we present a detailed analysis of the current phenomenological status of the charged Higgs sector in a variety of well-motivated two Higgs doublet models (2HDMs). We find that charged Higgs bosons as light as

AlterBBN: A program for calculating the BBN abundances of the elements in alternative cosmologies☆

75~\mathrm {GeV}