Farvah Mahmoudi

SuperIso v2.3: A program for calculating flavor physics observables in supersymmetry

We describe SuperIso v2.3 which is a public program for evaluation of flavor physics observables in the minimal supersymmetric extension of the Standard Model (MSSM). SuperIso v2.3, in addition to the isospin asymmetry of B→K∗γ, which was the main purpose of the first version, incorporates new flavor observables such as the branching ratio of Bs→μ+μ−, the branching ratio of B→τντ, the branching ratio of B→Dτντ and the branching ratio of K→μνμ. The calculation of the branching ratio of B→Xsγ is also improved in this version, as it now includes NNLO Standard Model contributions in addition to partial NLO supersymmetric contributions. The program also computes the muon anomalous magnetic moment (g−2). Four sample models are included in the package, namely mSUGRA, NUHM, AMSB and GMSB. SuperIso uses a SUSY Les Houches Accord file (SLHA1 or SLHA2) as input, which can be either generated automatically by the program via a call to external spectrum calculators, or provided by the user. The calculation of the observables is detailed in the Appendices, where a suggestion for the allowed intervals for each observable is also provided.

SuperIso: A program for calculating the isospin asymmetry of B→K∗γ in the MSSM

Abstract We present a program for calculating the isospin symmetry breaking in B → K ∗ γ decays in the MSSM with minimal flavor violation. This program calculates the NLO supersymmetric contributions to the isospin asymmetry, using the effective Hamiltonian approach and within the QCD factorization method. We show that isospin symmetry breaking proves to be a very restrictive observable, in particular in the mSUGRA parameter space. The program also calculates the inclusive branching ratio associated to b → s γ transition, as a comparison reference. Program summary Program title: SuperIso Catalogue identifier: AEAN_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEAN_v1_0.html Program obtainable from: CPC Program Library, Queens University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3537 No. of bytes in distributed program, including test data, etc.: 23u2009595 Distribution format: tar.gz Programming language: C (C99 Standard compliant) Computer: 32- or 64-bit PC, Mac Operating system: Linux, MacOS RAM: less than 1 MB Classification: 11.6 External routines: ISASUGRA/ISAJET ( http://www.hep.fsu.edu/~isajet/ ) and/or SOFTSUSY ( http://projects.hepforge.org/softsusy ) Nature of problem: Calculation of isospin asymmetry in B → K ∗ γ decays in the Minimal Supersymmetric extension of the Standard Model with minimal flavor violation. This observable brings severe constraints on the supersymmetric parameter space. Solution method: SuperIso uses a SUSY Les Houches Accord file, which can be either generated automatically by calling SOFTSUSY or ISAJET, or provided by the user. This file contains the masses and couplings of the supersymmetric particles. SuperIso then computes Wilson coefficients, which are used to calculate the isospin symmetry breaking in B → K ∗ γ decays, as well as the inclusive branching ratio of B → X s γ . SuperIso is able to perform the calculation in different supersymmetry breaking scenarios, such as mSUGRA, AMSB and GMSB. Restrictions: This calculation is valid only in the MSSM with minimal flavor violation. Unusual features: The code is very modular, and new routines for calculating new physical observables such as the branching ratio of B s → μ + μ − , can be easily added. Additional comments: The module which reads the SUSY Les Houches Accord file can be used independently in other programs. Running time: 0.1 sec

Charged Higgs bosons in minimal supersymmetry: updated constraints and experimental prospects

We discuss the phenomenology of charged Higgs bosons in the MSSM with minimal flavor violation. In addition to the constrained MSSM (CMSSM) with universal soft supersymmetry breaking mass parameters at the GUT scale, we explore non-universal Higgs mass models (NUHM) where this universality condition is relaxed. To identify the allowed parameter space regions, we apply constraints from direct searches, low energy observables, and cosmology. We find that values of the charged Higgs mass as low as mH+ xa0135 GeV can be accommodated in the NUHM models, but that several flavor physics observables disfavor large H+ contributions, associated with high tanxa0β, quite independently of MSSM scenario. We confront the constrained scenarios with the discovery potentials reported by ATLAS and CMS, and find that the current exclusion by indirect constraints is similar to the expected LHC discovery reach with 30 fb−1 of data. Finally, we evaluate the sensitivity of the presented discovery potential to the choice of MSSM benchmark scenario. This sensitivity is found to be higher in the case of a light (mH+xa0<xa0mt) charged Higgs.

SUSY constraints from relic density: High sensitivity to pre-BBN expansion rate

Abstract The sensitivity of the lightest supersymmetric particle relic density calculation to the variation of the cosmological expansion rate before nucleosynthesis is discussed. Such a modification of the expansion rate, even extremely modest and with no consequence on the cosmological observations, can greatly enhance the calculated relic density, and therefore change the constraints on the SUSY parameter space drastically. We illustrate this variation in two examples of SUSY models, and show that it is unsafe to use the lower bound of the WMAP limits in order to constrain supersymmetry. We therefore suggest to use only the upper value Ω DM h 2 0.135 .

Associated production of a Kaluza–Klein excitation of a gluon with a tt¯ pair at the LHC

Abstract In certain model-realizations of the Randall–Sundrum scenario, the Kaluza–Klein (KK) excitations of the gluon, g KK have enhanced couplings to right-handed top quarks. In the absence of a g g g KK coupling in these models, the single production of a g KK from an initial gg state is not possible. The search for other production mechanisms at the LHC, therefore, becomes important. We suggest that the associated production of a g KK with a t t ¯ pair is such a mechanism. Our parton-level study, which neglects detection efficiencies, shows that through this process the LHC can probe KK gluon masses in the range of 2.8–3.0 TeV.

New constraints on supersymmetric models from b ---> s gamma

We provide an analysis of the parameter space of several supersymmetry breaking scenarios such as the minimal supergravity (mSUGRA) model and the non universal Higgs mass (NUHM) framework, as well as the Anomaly Mediated Supersymmetry Breaking (AMSB) and the Gauge Mediated Supersymmetry Breaking (GMSB) models, in the light of a novel observable in b → sγ transitions, i.e. the isospin symmetry breaking in the exclusive B → K*γ decays. We find that in many cases, this observable provides severe restrictions on the allowed parameter space regions for the mentioned models. Moreover, we provide a few examples of investigations of the physical masses of supersymmetric particles and search for the excluded values. The constraints from the branching ratio associated to b → sγ are also presented here for all the examined parameter space regions. A comparison with Bs → μ+μ− branching ratio has also been performed.

The CP-violating type-II 2HDM and Charged Higgs boson benchmarks

We review and update the interpretation of the 125 GeV scalar as the lightest Higgs boson of the Two-Higgs-Doublet Model, allowing for CP violation in the potential. The detection of a charged Higgs boson would exclude the Standard Model. Proposed benchmarks for charged- Higgs searches in the channel pp!H+W

Charged Higgs boson benchmarks in the CP-violating type-II 2HDM

We discuss prospects for discovering a charged Higgs boson in the CP-violating type-II two-Higgs-doublet Model. In the light of recent LHC data, we focus on the parameter space that survives experimental as well as the theoretical constraints on the model. Once the phenomenological scenario is set, we analyse the scope for the LHC to discover a charged Higgs in association with the lightest neutral Higgs and a charged vector boson.

Flavor Data Constraints on the SUSY Parameter Space

We present an overview of the indirect constraints from flavor physics on supersymmetric models. During the past few years flavor data, and in particular b→sγ transitions, have been extensively used in order to constrain supersymmetric parameter spaces. We will briefly illustrate here the constraints obtained by a collection of low energy observables including FCNC transitions, rare decays, leptonic and semileptonic decays of B mesons, as well as leptonic decays of K mesons. The theoretical predictions can be obtained using the computer program SuperIso.

Estimating the annihilation decay B_s -> rho gamma with factorization

The branching ratio for the rare two-body B_s -> rho gamma decay is calculated using the factorization assumption. This transition is dominated by the annihilation diagrams and, in principle, prone to receiving substantial contributions from new physics. We estimate Br(B_s -> rho gamma) = 1.6 x 10^-9 within the Standard Model and investigate the sensitivity of this decay mode to the effects of two new physics scenarios: vector quark model and supersymmetry. Our results indicate that the shift in branching ratio is at most around 10% with the addition of vector quarks and is negligibly small in the constrained minimal supersymmetric extension of the Standard Model.