Presentation on theme: "Lg ̃M & LHC JiJi Fan Yale University w/ A.D.Simone, M.Schmaltz and W.Skiba arXiv: 0808.2052 [hep-ph]"— Presentation transcript:
Lg ̃M & LoL @ LHC JiJi Fan Yale University w/ A.D.Simone, M.Schmaltz and W.Skiba arXiv: 0808.2052 [hep-ph]
Low-scale gaugino mediation: lots of leptons at the LHC JiJi Fan Yale University w/ A.D.Simone, M.Schmaltz and W.Skiba arXiv: 0808.2052 [hep-ph]
Finally the LHC starts collecting data! Supersymmetry or MSSM will be tested. MSSM: 105 soft parameters already constrained by FCNC and CP violation and must have some “organizing principle”. Mediation Scheme: gravity mediation, gauge mediation, anomaly mediation, gaugino mediation….
Sketches of sample spectrum from different models mSugra mGMSB w/ N 5 =1 Sfermions not much lighter than gauginos:
Motivation Some different spectrum?! Scalar superpartners much lighter than gauginos? Spectrum of low-scale gaugino mediation
Gaugino Mediation (Kaplan, Kribs and Schmaltz; Chacko, Luty, Nelson and Ponton 99’) At m 0 generated radiatively from m 1/2 : threshold effects at the messenger scale; : threshold effects at the gaugino mass scale; : Log running between the two scales. In original models,
Low-scale Gaugino Mediation( Lg̃M ) A.D. Simone, J.F, M. Schmaltz and W. Skiba (arXiv:0808.2052(hep-ph)) Low messenger scale, small Log running After including color factors and the log’s, scalar masses are still smaller than gaugino masses by a factor of a few (≥ 2).
Spectrum of Lg̃M Scalar superpartners much lighter than gauginos; Colored spaticles heavier than non-colored ones. The lightest superparners, in the mass increasing order, are the gravitino, right-handed sleptons and left-handed sleptons. Many decay chains pass through the left-handed sleptons and end in additional leptons. Typical signal: Also
A simple model based on “deconstructed g̃M” (Cheng, Kaplan, Schmaltz and Skiba; Csaki, Erlich, Grojean and Kribs 01’) Setup At Λ~5 TeV,
Assume SUSY breaking only couples to the fields charged under B gauge group. (can be realized through extra dimension setup or gauge mediation with messengers only charged under G B …). Phenomenologically, : SU(5) B gaugino soft mass; : link fields’ soft mass; MSSM gaugino mass: at tree-level from the mixing of A and B gauge groups In the limit m B « M (M: heavy gauge boson masses)
MSSM soft scalar masses: one-loop w/ gauge multiplets and the link fields and soft mass insertions. Gaugino loop Link field loop To have EWSB, must consider a negative 2-loop top-stop-gluino contribution to soft masses of H u.
Sample Spectrum LSP: Gravitino NLSP: τ̃ R NNLSP’s: Left-handed sleptons (Similar spectrum has been obtained through warped 5D constructions: Chacko, Ponton 03’; Medina, Wagner 06’)
Cross section for squark pair production and interesting final states with multi-leptons and Higgses at the LHC; each final state includes 2j+2 stable charged tracks.
Conclusions and future directions Lg̃̃̃M predicts that sfermions much lighter than gauginos; Hallmark of Lg̃M is that both left- and right- handed sleptons are lighter than all other sparticles except the gravitino. Study of the different signatures and the searching strategies. Distinguishing from other models with similar spectrum: Dirac gaugino model (“supersoft models” Fox, Nelson and Weiner 02’) ; GMSB w/ a large number of messengers (>30) … Model building issues: generate the scale dynamically; mu/Bmu; gauge coupling unification.