SUSY 09, Northeastern University June 7, 2009 Leptogenic Supersymmetry Andrea De Simone Massachusetts Institute of Technology Based on arXiv:0903.5305 with J. Fan, V. Sanz, W. Skiba
Leptogenic Supersymmetry SUSY 09 OUTLINE What is Lepto-SUSY? Main Features Phenomenology. Channels with: 4 leptons Higgs Andrea De Simone (MIT) 1/18
Leptogenic Supersymmetry SUSY 09 WHAT IS LEPTO-SUSY? Yet another SUSY model? No... A particular ordering of the SUSY spectrum. Not interested in how the hierarchy of masses gets generated at high energies. Look at what LHC can access. Striking and unusual collider signatures. Andrea De Simone (MIT) 2/18
Leptogenic Supersymmetry SUSY 09 WHAT DOES “LEPTOGENIC” MEAN? Leptogenic spectrum: ˜ g ˜ q Many leptons are produced in ˜ χ cascade decays Energetic Jets ˜ Leptons ℓ L Leptons stable ˜ Higgses ℓ R charged χ ± > m ˜ m ˜ g , m ˜ q > m ˜ χ 0 , m ˜ ℓ L > m h , m ˜ ℓ R Andrea De Simone (MIT) 3/18
Leptogenic Supersymmetry SUSY 09 SOME FEATURES Lepto-SUSY Gauginos heavier than scalars. spectrum All sleptons lie at the bottom. ˜ g ℓ L ˜ ˜ ℓ R The decay chains pass through , ˜ q and produce many leptons. Jets ˜ ˜ χ ℓ R NLSP : long-lived, collider stable. Leptons No significant missing energy! ˜ ℓ L Leptons (SUSY models with neutralino LSP, / ˜ give large ). E T Higgses ℓ R stable charged Gravitino LSP, no role at colliders. Andrea De Simone (MIT) 4/18
Leptogenic Supersymmetry SUSY 09 SOME FEATURES Lepto-SUSY Higgs is produced in slepton spectrum h → b ¯ decays. : important channel. b ˜ g ˜ q Several classes of models give rise Jets to a Lepto-SUSY spectrum ˜ χ Leptons (GMSB with large Nmess, ˜ Gaugino mediation at low-scale, ℓ L AMSB ...) Leptons ˜ Higgses ℓ R stable ...or just the MSSM in a region of its charged parameter space Andrea De Simone (MIT) 5/18
Leptogenic Supersymmetry SUSY 09 PRODUCTION AND DECAY √ s = 14 TeV Strong production cross- Σ � pb � 10 section. q ¯ q + ¯ q ¯ pp → ˜ q + ˜ ˜ q ˜ ˜ ˜ q 1 0.1 Squark-pair production is the 0.01 pp → ˜ q ˜ g dominant process. 0.001 � � GeV � m q 600 800 1000 1200 1400 1600 1800 2000 Andrea De Simone (MIT) 6/18
Leptogenic Supersymmetry SUSY 09 PRODUCTION AND DECAY √ s = 14 TeV Strong production cross- Σ � pb � 10 section. q ¯ q + ¯ q ¯ pp → ˜ q + ˜ ˜ q ˜ ˜ ˜ q 1 0.1 Squark-pair production is the 0.01 pp → ˜ q ˜ g dominant process. 0.001 � � GeV � m q 600 800 1000 1200 1400 1600 1800 2000 ν j Typical final state of squark ℓ ℓ ˜ χ + ℓ L cascade decays: ˜ ℓ R q ˜ 2 jets + (2,3,4) leptons + p p → 2 stable charged tracks q ˜ χ 0 ˜ ℓ R No significant missing energy. j ℓ Andrea De Simone (MIT) 6/18
Leptogenic Supersymmetry SUSY 09 BENCHMARK POINTS Lepto-SUSY is not in ATLAS/CMS benchmark points! LS1: squark masses ~ 1 TeV LS2: squark masses ~ 520-700 GeV sleptons ~ 110 GeV Production cross-section (fb) 10 TeV 14 TeV Higgs ~ 115 GeV LS1 680 2170 LS2 5040 13700 Andrea De Simone (MIT) 7/18
Leptogenic Supersymmetry SUSY 09 BENCHMARK POINT “LS1” mass (GeV) GeV gluino: 1938 m ˜ g neutralinos: 271 m χ 0 ˜ q L 1 302 m χ 0 ˜ q R 2 900 353 m χ 0 3 676 m χ 0 4 charginos: 291 m χ ± 800 1 676 m χ ± 2 Higgs: 115 m h 0 χ ± χ 0 700 379 m H 0 2 4 379 m A 600 387 m H ± 294 µ � 119 B µ 500 sleptons: 108 m ˜ ℓ R 248 m ˜ ℓ L χ 0 400 236 m ˜ ν 3 106 m ˜ χ 0 τ 1 χ ± 249 m ˜ 2 τ 2 300 1 χ 0 squarks: 949 m ˜ ˜ u L ℓ L 1 920 m ˜ u R 200 952 m ˜ d L 919 m ˜ d R ˜ ℓ R 920 m ˜ 100 t 1 962 m ˜ t 2 Andrea De Simone (MIT) 8/18
Leptogenic Supersymmetry SUSY 09 SLEPTONS OR MUONS? Long-lived sleptons hits like muons with lower β � measured Fast sleptons ( β > 0.9) 1 misidentified as muons 0.9 0.8 0.7 0.6 10000 ATLAS β ˜ 8000 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 ℓ Number of Events generated � 6000 [ATLAS TDR 2008] 4000 2000 Many sleptons are very fast 0 0.5 0.6 0.7 0.8 0.9 1 in the signal � slepton Andrea De Simone (MIT) 9/18
Leptogenic Supersymmetry SUSY 09 CHANNELS -1 L=1 fb Focus on channels with: 90 80 p jet Number of Events/20 GeV 70 T 2 hard jets 60 50 40 ≥ 4 lepton-like particles 30 20 (leptons or stable sleptons) 10 0 0 200 400 600 800 1000 1200 1400 Leading jet p T New channels for SUSY searches! Almost background-free. Mass reconstruction of several sparticle states. Statistically significant excesses of events already Higgs can be discovered in h → b ¯ at low luminosity ( ≤ 1 fb -1 ). the mode. b Andrea De Simone (MIT) 10/18
Leptogenic Supersymmetry SUSY 09 4-LEPTONS CHANNEL ℓ j seen as muons ˜ χ 0 ℓ R q ˜ p p → χ 0 q ˜ ˜ ℓ R Event selection: (including sleptons) j n ℓ = 4 ℓ n jet ≥ 2 10 TeV 14 TeV with standard cuts σ (fb) | η jet | < 2 . 5 , | η ℓ | < 2 . 5 220 690 p jet p ℓ T > 15 GeV , T > 10 GeV Events at 45 140 0.2 fb -1 ∆ R jj , ℓℓ , ℓ j > 0 . 4 Andrea De Simone (MIT) 11/18
Leptogenic Supersymmetry SUSY 09 4-LEPTONS CHANNEL m j ℓ ˜ ℓ m ℓ ˜ ℓ ℓ j χ 0 1 , χ 0 It allows 3 , ˜ q mass reconstruction. ˜ χ 0 ℓ R q ˜ p p → Channel with no MET. χ 0 q ˜ ˜ No MET cut imposed. ℓ R j ℓ Hard cuts on the of the leading jet can be applied p T and suppress the BG efficiently. All SM BGs are below 1 fb. Andrea De Simone (MIT) 12/18
Leptogenic Supersymmetry SUSY 09 4-LEPTONS CHANNEL 60 120 OSL pairs selected χ 0 χ 0 3 3 50 100 according to minimal -1 -1 Number of Events/5 GeV/1 fb Number of Events/5 GeV/1 fb χ 0 40 Δ R separation. 80 1 χ 0 30 60 1 20 40 10 20 0 0 ˜ 200 220 240 260 280 300 320 340 360 380 400 200 220 240 260 280 300 320 340 360 380 400 q R dilepton mass(GeV) lepton-slepton mass(GeV) 25 -1 Number of Events/10 GeV/1 fb sleptons misidentified sleptons identified 20 15 Further pairing with the nearest jet 10 5 800 850 900 950 1000 1050 1100 jet+lepton+slepton mass (GeV) Andrea De Simone (MIT) 13/18
Leptogenic Supersymmetry SUSY 09 HIGGS CHANNEL Standard lore: No Higgs searches in b-bbar, due to large BG. In Lepto-SUSY: Higgs is copiously produced ℓ L → h ˜ ˜ in slepton decays , ℓ R ¯ ℓ j b h 0 b χ 0 and then decays to b-bbar. µ 2 (˜ ˜ τ 2 ) µ 1 (˜ ˜ τ 1 ) ˜ q p p → BG efficiently suppressed ˜ q by lepton multiplicity. χ 0 ˜ ℓ R j ℓ is a discovery channel. h → b ¯ b Andrea De Simone (MIT) 14/18
Leptogenic Supersymmetry SUSY 09 HIGGS CHANNEL Analysis ( simple-minded and conservative ): ask for and n jet ≥ 4 n ℓ = 3 , 4 order jets in pT and ask 4th pT>25 GeV assume 1st and 2nd jets are from squarks form invariant mass of 3rd and 4th jets NB: No b-tagging. 2 3 , 4 τ , µ ¯ ℓ b j Not precisely known at h 0 b χ 0 early stages. µ µ 2 (˜ ˜ τ 2 ) µ 1 (˜ ˜ τ 1 ) q ˜ 10 TeV 14 TeV p p → σ (fb) 100 320 ˜ q µ χ 0 ˜ Events at ℓ R 20 64 j ℓ 0.2 fb -1 1 Andrea De Simone (MIT) 15/18
Leptogenic Supersymmetry SUSY 09 HIGGS CHANNEL -1 -1 L= 1 fb , Etm < 40 GeV (LS1) L= 1 fb , Etm < 40 GeV (LS1) P -P > T1 T3 16 14 TeV to 10 TeV 100 GeV 300 GeV h 0 15 9 is a factor of ~1/3 14 Z 8.5 13 Events/10 GeV Events/10 GeV LS 1 12 8 11 10 7.5 9 7 8 7 6.5 6 60 70 80 90 100 110 120 130 50 60 70 80 90 100 110 120 130 140 150 m (GeV) m (GeV) dijet dijet -1 -1 L= 1 fb , Etm < 40 GeV (LS2) L= 1 fb , Etm < 40 GeV (LS2) Combinatorial BG: P -P > T1 T3 45 100 GeV 200 GeV 120 h 0 more detailed 300 GeV Z 40 100 analysis needed. 35 Events/10 GeV Events/10 GeV LS 2 80 30 Under study by 60 25 ATLAS coll. 40 20 20 50 60 70 80 90 100 110 120 130 140 150 60 70 80 90 100 110 120 130 m (GeV) m (GeV) dijet dijet Andrea De Simone (MIT) 16/18
Leptogenic Supersymmetry SUSY 09 DISCOVERY PROSPECTS The ease of multi-leptonic channels (~absence of BG) implies a tremendous discovery potential of LHC. The discovery of the stable slepton is possible with the very first data. Most of the sparticle spectrum can be reconstructed (at least 10 clean events) with 0.2 - 0.4 fb -1 at 10 TeV (for TeV-squarks) h → b ¯ Prospects of Higgs discovery in the channel may b be good with ≤ 1 fb -1 at 14 TeV. Significance of this channel requires full simulation. Andrea De Simone (MIT) 17/18
Leptogenic Supersymmetry SUSY 09 CONCLUSIONS Leptogenic SUSY spectra are characterized by many leptons in the final state of pp collisions. They arise in several well-motivated models. Extremely clean (almost BG-free) channels. One of the most “LHC-friendly” SUSY scenarios. Different from standard SUSY searches. Relevant for very early stage of LHC. It can be discovered/ruled out with ~ 0.2 fb -1 at 10 TeV. Andrea De Simone (MIT) 18/18
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