RWTH Aachen Particle Physics Theory

Back from the SUSY conference

July 29th, 2014 | by

Jory and Mathieu are PHD students working on beyond the standard model physics. They presented their current projects (click and click) at the SUSY 2014 conference in Manchester last week. Read on about their experiences at the conference…

manchesterSUSY 2014, 21-26 July 2014 in Manchester (UK)

by Jory & Mathieu

Manchester is not only “the theatre of the dreams” of football.

It is also the home city of the nobel prize laureate Konstantin Novoselov who gave a         public lecture on graphene on Thursday. But more important, it is where the 22nd  International Conference on Supersymmetry (SUSY) and Unification of Fundamental  Interactions took place.

All possible subjects related to SUSY were covered at this conference, ranging from formal SUSY theories and strings to phenomenology of SUSY at the Large Hadron Collider (LHC) operating in Geneva (Switzerland). With the discovery of the Higgs boson, the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) is under high scrutiny. In particular, numerous Higgs fits and scans of the Higgs sector parameters are currently being performed.

On top of the “standard” MSSM, more elaborate implementations of SUSY, such as the nMSSM, the complex MSSM, and other extensions of the MSSM have been and are now being developed. Other topics in the context of SUSY, such as dark matter and cosmology, have been discussed intensively. Specifically, codes for generating the relic density that take into account higher order corrections have been presented.

In SUSY phenomenology, where the cMSSM looks more and more cornered, simplified models were being used to fit excesses in CMS lepton searches (with success). More effort has also gone into using simpler version of the MSSM, e.g. the pMSSM, to obtain better limits on SUSY models. Much of the allowed parameter space, however, lies outside the current 8 TeV range.

As SUSY particle masses are being excluded up to higher values, naturalness in SUSY is now harder to obtain. All the corners of the (N)MSSM are being explored to obtain it. Other models than the MSSM, like models with Dirac gluinos, also allow for lighter SUSY particles and hence more naturalness.

In the field of loop corections, results at NLO and NNLL have been made public. Moreover, higher-precision calculations (including multi-loops and resummation) for the Higgs mass and the Z boson mass in the MSSM have been released. These calculations compete with the experimental precision and hence possibly exclude an important part of the phase space of the MSSM parameters.

On top of the standard perturbation technique using Feynman diagrams, the amplitude formalism was introduced. It could have a great impact on our way of calculating cross sections at the multiloop level for complicated processes. Nevertheless, it seems that the developments in this field are still far from calculating a cross section at NLO in a broken theory or even in the \phi^4 theory.

During the week, there were also non-SUSY talks on topics such as neutrinos, flavor or scale invariance. On the experimental side, obviously no discovery has been reported – otherwise you would have heard about it. The exclusion limits are increasing both in the Higgs sector and for strongly interacting colored particles. These results come mainly from the run 1 of the LHC but also from direct detection experiments for dark matter.

Nevertheless, the excitation is not gone! Indeed, the CMS experiment reported an excess of a few sigma (see CMS PAS SUS-14-002). As usual, many theories are on the market and SUSY is a competitive one. The run 2 of the LHC will hopefully clarify which theory accounts for this excess, if any…

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