Search for stable hadronising squarks and gluinos with the ATLAS experiment at the LHC

In the context of the MSSM the Light Stop Scenario (LSS) is the only region of parameter space that allows for successful Electroweak Baryogenesis (EWBG). This possibility is very phenomenologically attractive, since it allows for the direct production of light stops and could be tested at the LHC. The ATLAS and CMS experiments have recently supplied tantalizing hints for a Higgs boson with a mass of ≈ 125 GeV. This Higgs mass severely restricts the parameter space of the LSS, and we discuss the specific predictions made for EWBG in the MSSM. Combining data from all the available ATLAS and CMS Higgs searches reveals a tension with the predictions of EWBG even at this early stage. This allows us to exclude EWBG in the MSSM at greater than (90) 98% confidence level in the (non-)decoupling limit, by examining correlations between different Higgs decay channels. We also examine the exclusion without the assumption of a ≈ 125 GeV Higgs. The Higgs searches are still highly constraining, excluding the entire EWBG parameter space at greater than 90% CL except for a small window of m h ≈ 117 − 119 GeV.

Section: Lss and A Heavy Higgsmentioning

confidence: 99%

Excluding electroweak baryogenesis in the MSSM

Curtin

Jaiswal

Meade

2012

“…Furthermore, negative LHC SUSY searches have also suggested that the SUSY spectrum might be far heavier than what had previously been considered [89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107]. Moreover, the sensitivity of the experiments dedicated to the observation of low-energy cLFV transitions has also significantly improved [108], especially in what concerns µ → eγ decays [109] and µ − e conversion in nuclei [110,111].…”

Section: Jhep08(2012)138mentioning

confidence: 99%

“…The low-energy sparticle masses and mixings have been numerically evaluated with the SPheno public code [121]. LHC bounds on the SUSY spectrum [89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107] have been applied; in all cases, the lightest Higgs mass is around 117 GeV, still marginally compatible with the new LHC data [122,123]. Notice that the non-minimal SUSY scenarios can still be considered to accommodate such data, with a minimal impact concerning the present lepton flavour dedicated analysis.…”

Section: Jhep08(2012)138mentioning

confidence: 99%

Lepton flavour violation: physics potential of a Linear Collider

Abada

Figueiredo

Romão³

et al. 2012

Abstract:We revisit the potential of a Linear Collider concerning the study of lepton flavour violation, in view of new LHC bounds and of the (very) recent developments in lepton physics. Working in the framework of a type I supersymmetric seesaw, we evaluate the prospects of observing seesaw-induced lepton flavour violating final states of the type e µ plus missing energy, arising from e + e − and e − e − collisions. In both cases we address the potential background from standard model and supersymmetric charged currents. We also explore the possibility of electron and positron beam polarisation. The statistical significance of the signal, even in the absence of kinematical and/or detector cuts, renders the observation of such flavour violating events feasible over large regions of the parameter space. We further consider the µ − µ − + E T miss final state in the e − e − beam option finding that, due to a very suppressed background, this process turns out to be a truly clear probe of a supersymmetric seesaw, assuming the latter to be the unique source of lepton flavour violation.

“…As seen above, the decay of the new heavy states takes place through suppressed operators, leading to long lifetimes. The search for new long-lived states is conducted by the ATLAS and CMS collaboration using several experimental techniques, such as dE/dx, time of flight and decays during beam collision intervals [1][2][3][4].…”

Section: Experimental Searches: Production and Detectionmentioning

confidence: 99%

“…Experiments at the Large Hadron Collider (LHC) have published their first results on the production of quasi-stable hadrons that are stopped and decay in the detectors [1][2][3][4][5]. Besides special cases of supersymmetric and extra-dimensional models, other models of different sorts also predict heavy particles with delayed decays [6], and many will be checked in turn at the LHC.…”

Section: Introductionmentioning

confidence: 99%

A rationale for long-lived quarks and leptons at the LHC: low energy flavour theory

Éboli

Savoy

Funchal

2012

In the framework of gauged flavour symmetries, new fermions in parity symmetric representations of the standard model are generically needed for the compensation of mixed anomalies. The key point is that their masses are also protected by flavour symmetries and some of them are expected to lie way below the flavour symmetry breaking scale(s), which has to occur many orders of magnitude above the electroweak scale to be compatible with the available data from flavour changing neutral currents and CP violation experiments. We argue that, actually, some of these fermions would plausibly get masses within the LHC range. If they are taken to be heavy quarks and leptons, in (bi)-fundamental representations of the standard model symmetries, their mixings with the light ones are strongly constrained to be very small by electroweak precision data. The alternative chosen here is to exactly forbid such mixings by breaking of flavour symmetries into an exact discrete symmetry, the so-called proton-hexality, primarily suggested to avoid proton decay. As a consequence of the large value needed for the flavour breaking scale, those heavy particles are long-lived and rather appropriate for the current and future searches at the LHC for quasi-stable hadrons and leptons. In fact, the LHC experiments have already started to look for them.