Searching supersymmetric leptonic partner at the CERN LHC

Abstract

Motivated by the observed excess of the di-photon signal in Higgs searches, σ γγ /σ SM ≃ 1.5, we argue that models with enhanced Γ(h → γγ) alone are the most favorable scenarios when the latest LHC/Tevatron results are all taken into account. We study the phenomenology of a supersymmetric scenario of light stau first proposed by Carena et. al. [1] that predicts a 125 GeV SM-like Higgs boson with enhanced diphoton decay through light stau loops. Since it is extremely challenging to search the Drell-Yan stau pair at the LHC due to the small production rate, we focus on the parameter space with enhanced production of inclusive stau pairs, in particular, via bb fusion or gaugino pairs. We study its phenomenology in both pure leptonic tau τ ± ℓ channels and hadronic tau tagged τ h channels. We find the same-sign dilepton fromχ ± 1χ 0 2 → τ ± ℓ τ ± ℓ + X may significantly improve the discovery potential with even 7-8 TeV LHC of O(30 fb −1 ) data. In the case of hadronic tau pair, we use the final state j +τ h τ h + E T to search and find that even with the most optimistic region of M 2 ∼ 200 − 300 GeV, it requires at least 50 fb −1 data of 14 TeV LHC to reach a significance of 3.5 σ. Therefore, we conclude it is difficult to claim discovery only through hadronic tau based on the data by the 2012 shut-down. 5 σ reach for our most optimistic region then requires 100 fb −1 data with 14 TeV running.a Corresponding

MSSM: cornered and correlated

“…In this article we dissect the "light stau scenario" extending previous analyses [3,4,6,10,12,16] that are similar in spirit. In particular, we will show that enhancements of the pp → h → γγ signal associated to virtual stau exchange occur only in a narrow sliver in MSSM parameter space that features large (and positive) values of tan β, the trilinear coupling A t , and the µ parameter.…”

“…In the MSSM, the modification of the Higgs-boson production cross section in gg → h, can be approximated by 6) where κt and κb represents the effects of top-squark and bottom-squark triangles, respectively. Notice that (2.6) ignores the fact that the top-quark and bottom-quark Yukawa couplings in the MSSM differ from those in the SM.…”

“…An economic possibility to modify the effective coupling between the Higgs boson and two photons without altering its main decay modes is provided by extra vector-like leptonic states (see for example [3][4][5][6][7][8][9][10][11][12][13][14][15]). In the context of the minimal supersymmetric SM (MSSM) a light, maximally mixed stau can be shown to increase the loop-induced hγγ coupling [3], hence leading to the desired effect.…”

Light top squark in precision top quark sample

“…In the decoupling MSSM limit, the 125 GeV new particle can be identified as the lightest CP-even Higgs boson h. In order to predict m h =125 GeV, a large A t is necessary for moderate light stops [21][22][23][24][25][26][27][28][29]. Such a large A t -term would lead to a big splitting of stop masses.…”

Neutralino dark matter in gauge mediation after run I of LHC and LUX

“…Firstly, a SM-like Higgs boson with mass around 125 GeV has been confirmed at LHC [15,16]. A 125 GeV Higgs in decoupling MSSM scenario prefers either a heavy top squark (stop) or a large A t -term [17][18][19][20][21][22][23][24][25][26][27], since both could contribute large loop corrections to the Higgs mass. Unfortunately, minimal GMSB models predict vanishing A-terms at the messenger scale, which presents another challenge for GMSB models.…”