SUSY Les Houches Accord 2

Abstract

The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first SLHA to include various generalisations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavour, as well as the simplest next-to-minimal model. IntroductionSupersymmetric (SUSY) extensions of the Standard Model rank among the most promising and well-explored scenarios for New Physics at the TeV scale. Given the long history of supersymmetry and the number of people working in the field, several different conventions for defining supersymmetric theories have been proposed over the years, many of which have come into widespread use. At present, therefore, no unique set of conventions prevails. In principle, this is not a problem. As long as everything is clearly and consistently defined, a translation can always be made between two sets of conventions. However, the proliferation of conventions does have some disadvantages. Results obtained by different authors or computer codes are not always directly comparable. Hence, if author/code A wishes to use the results of author/code B in a calculation, a consistency check of all the relevant conventions and any necessary translations must first be made -a tedious and error-prone task.To deal with this problem, and to create a more transparent situation for non-experts, the original SUSY Les Houches Accord (SLHA1) was proposed [1]. This accord uniquely defines a set of conventions for supersymmetric models together with a common interface between codes. The most essential fact is not what the conventions are in detail (they largely resemble those of [2]), but that they are consistent and unambiguous, hence reducing the problem of translating between conventions to a linear, rather than a factorial, dependence on the number of codes involved. At present, these codes can be categorised roughly as follows (see [3,4] for a review and on-line repository):• Spectrum calculators [5][6][7][8], which calculate the supersymmetric mass and coupling spectrum, assuming some (given or derived) SUSY-breaking terms and a matching to known data on the Standard Model parameters.• Observables calculators [9][10][11][12][13][14][15][16][17][18][19]; packages which calculate one or more of the following: collider production cross sections (cross section calculators), decay partial widths (decay packages), relic dark matter density (dark matter packages), and indirect/precision observables, such as rare decay branching ratios or Higgs/electroweak observables (constraint packages).• Monte-Carlo event generators [20][21][22][23][24][25][26][27][28], which calculate cross sections through explicit statistical simulation of high-energy particle collisions. By including resonance decays, parton showering, hadronisation, and underlying-event effects, fully exclusive final states can be studied, and, for instance, ...

FeynRules 2.0 — A complete toolbox for tree-level phenomenology

“…Indeed, FeynRules is equipped with its own reading and writing routine for Les Houches Accord (LHA)-like parameter files [51,52]. For example, issuing the command…”

“…In other words, FeynRules creates two real external tensorial parameters, the real and imaginary parts of the matrix, and one internal complex tensorial parameter for the matrix UW itself. The user must specify the name of a Les Houches block [51,52] which will contain the numerical values associated with the elements of the matrix (see Section 6.1.4). In the example above, we impose the real part of the elements of U w to be stored in a block named WEAKMIX and their imaginary part in a block IMWEAKMIX.…”

The ATLAS Simulation Infrastructure

“…It contains only important processes from the Standard Model, the universal extra dimensions model, and supersymmetric models (whose details are specified via Supersymmetric Les Houches Accord model files [58,59]). Additional hard scattering processes can be used via "Les Houches" input from specialized generators, and additional decay models can be added by users.…”

Search for Supersymmetry in pp Collisions at √s = 8 TeV with a Photon, Lepton, and Missing Transverse Energy

“…The input mass spectrum for each mass point is written in a SUSY Les Houches Accord (SLHA) [100] file produced by SuSpect2.41 [101] and SDECAY1.3 [102]. The former program calculates the mixing matrices given the input mass spectrum at the weak scale.…”