arXiv:1012.5762v2 [hep-ph] 10 Jan 2011 KIAS-P10048 An unusual signal of Higgs boson in supersymmetry at the LHC Priyotosh Bandyopadhyay, 1, ∗ Pradipta Ghosh, 2, † and Sourov Roy 2, ‡ 1 Korea Institute for Advanced Study, Hoegiro 87 (207-43 Cheongnyangni-dong), Seoul 130-722, Korea 2 Department of Theoretical Physics, Indian Association for the Cultivation of Science, 2A & 2B Raja S.C. Mullick Road, Kolkata 700 032, India (Dated: January 11, 2011) We predict an unusual signal of Higgs boson in R-parity violating non-minimal supersymmetric standard models at the Large Hadron Collider (LHC). The signal involves two stand-alone muons and four hadronic jets in the muon chamber of a general purpose detector at the LHC (CMS or ATLAS), originating from the decay of the lightest supersymmetric particle (LSP), predominantly a gauge-singlet neutrino by nature and having a large decay length (∼ 4-5 meter). A pair of such LSP can be produced in the decay of the lightest MSSM-like Higgs boson, produced through gluon fusion. An unconventional, background-free signature of this kind at the outer part of the detector may lead to a discovery even for the early LHC run at √ s = 7 TeV with 1 fb -1 of integrated luminosity. Additionally, a reliable mass reconstruction for the LSP of this type can give us a direct probe to the seesaw scale. PACS numbers: 12.60.Jv, 14.60.St, 14.80.Da, 14.60.Pq The quest for Higgs boson and physics beyond the standard model (SM) has led us to the era of Large Hadron Collider (LHC). Out of many proposed theo- ries, weak-scale supersymmetry (SUSY) has perhaps become the most popular choice for explaining new physics beyond the SM. However, in spite of many desirable features, SUSY theories are also not free from shortcomings. For example, the minimal su- persymmetric standard model (MSSM), suffers from the so-called μ-problem [1]. On the other hand, just like the SM, explaining the results of neutrino exper- iments is a task in which the MSSM is an apparent failure. The “μ from ν ” supersymmetric standard model or μν SSM [2, 3] is an R-parity violating ( R p ) [4] non- minimal SUSY model with three SM gauge-singlet right handed neutrino superfields (ˆ ν c i ), which gener- ate a TeV scale μ-term and can simultaneously ac- commodate [5–7] the existing data [8] from neutrino experiments, even at the tree level [5]. The indis- pensable point of this letter is that μν SSM can have unusual signatures of Higgs boson, potentially capa- ble of altering Higgs search strategies at the LHC. This unconventional and spectacular signature con- tains stand-alone muons (and electrons) and jets, which will produce visible tracks only in the muon chamber of the CMS or the ATLAS detector. The essential ingredient here is that the lightest supersymmetric particle (LSP) in μν SSM can be predominantly ( > ∼ 70%) a gauge-singlet field (hence- forth will be refereed to as the singlino LSP) and the Higgs boson (which is very similar to the light- est Higgs boson of MSSM, h 0 ) can couple to two singlino LSP. In fact, this feature is generically true in other  R p non-minimal SUSY models with gauge- singlet superfields. We analyze the pair production of singlino LSP at the LHC originating from the de- cay of the Higgs boson and the subsequent decays of each LSP involving three SM particles in the fi- nal state. A singlino LSP (  χ 0 1 ), for its gauge-singlet nature will travel a large distance (∼ 4-5 m) before decaying and finally decay into leptons and jets in the outer part of the detector. We look at a particu- lar final state pp → 2ℓ +4j + X, where ℓ is definitely a muon and can also be an electron, if electron de- tection is possible in the muon chamber. A faithful detection of these stand-alone muons and hadronic jets in the outer part of the detector can lead to a reliable mass reconstruction for  χ 0 1 and the Higgs bo- son h 0 . Additionally, invariant mass reconstruction for a singlino LSP can provide information about the seesaw scale since the right-handed neutrinos are operational in light neutrino mass generation in μν SSM through a TeV scale seesaw mechanism. We show that such an unusual signal of supersymmetric Higgs boson can be observed even for the early run of LHC with center-of-mass energy, √ s = 7 TeV and with 1 fb −1 of integrated luminosity. Nevertheless, we also present our results for √ s = 14 TeV.