Distinguishing between SUSY and Littlest Higgs Model using - PowerPoint PPT Presentation

Distinguishing between SUSY and Littlest Higgs Model using trileptons at the LHC (Pheno’09, Madison) A. Datta, P . Dey, S.K. Gupta, B. Mukhopadhyaya, A. Nyffeler [Phys. Lett. B] We will work with R-parity conserving MSSM and T-parity conserving Littlest Higgs Model (LHT). • The idea of Littlest Higgs Model is based upon viewing Higgs Boson as a Goldstone Boson. • The Littlest Higgs Model with T-parity and MSSM with R-parity shares the following common features: – Both have T/R-odd partners corresponding to each SM content. – Lightest T/R-odd particle is stable and hence a viable candidate for cold dark matter of the universe. – T/R-odd particles are pair produced and decays into LTP/LSP through cascades and therefore they carry huge amount of missing tranverse energy. - p. 1/12

LHT differs with MSSM in the following: – (T-odd) partners of Standard Model particles have the same spin unlike SUSY where the (R-odd) superpartners of the Standard Model differ by a spin 1/2. "Bosonic SUSY" – Absence of T-odd partner of gluon and presence of extra (T-odd and -even) tops. - p. 2/12

Sources of trileptons in LHT and SUSY W ± W ± q q H H W ± q H W ± q ′ q H H q ′ Z H q ′ q ′ Z H Z H (a) χ ± χ ± � � q q 1 1 χ ± q � 1 W ± q ′ ˜ ˜ q q ′ χ 0 � q ′ q ′ 2 χ 0 χ 0 � � 2 2 (b) followed by W ± H → A H W ± → A H l ′± ν l ′ , Z H → A H Z → A H l ± l ∓ , 1 → ν l ′ e 2 → l ± e χ ± l ′± → e 1 l ′± ν l ′ , l ∓ → e 1 l ± l ∓ . χ 0 χ 0 χ 0 e e - p. 3/12

Assumptions • Assume the mass spectra of LHT and MSSM to be identical (not all states can be matched !) • Assume that we have some information on these masses from the first phase of LHC. • Assume that gluino is heavy → no QCD-enhanced SUSY events ⇒ Hadronically quiet trilepton event rates could distinguish between the two models (at least in some region of the parameter space) - p. 4/12

Matching SUSY spectrum with LHT LHT spectrum can be essentially determined by 3 parameters: ( f, κ q , κ l ) • ( � l, � q ) masses equated to ( l H , q H ) masses • ( A H , W ± χ ± χ 0 χ 0 H , Z H ) masses aligned to ( � 1 , � 1 , � 2 ) setting: - Bino mass M 1 set equal to m A H χ ± χ 0 - M 2 = m Z H and µ = 1 . 5 TeV → pair ( � 1 , � 2 ) is Wino dominated → SUSY scenario 1 (SS1) χ ± χ 0 - µ = m Z H and M 2 = 1 . 5 TeV → pair ( � 1 , � 2 ) is Higgsino dominated → SUSY scenario 2 (SS2) - Physical chargino and neutralino states obtained by diagonalization of respective mass matrices • M 3 = 5 TeV to decouple gluinos • Trilinear couplings set to zero (except A t ) • Lighter CP-even Higgs mass set to m H = 120 GeV • tan β = 10 , m A = 850 GeV - p. 5/12

LHT versus SUSY spectrum Masses and scale f in GeV: LHT SUSY f mAH mZH mdH muH mlH mνH m e m e m Case χ ± χ 0 χ 0 e 1 2 1 κl = κq = 1 500 66.2 316.7 707.1 685.7 707.1 685.7 65.9 314.9 314.9 SS1 63.7 314.9 318.1 SS2 1000 150.2 648.3 1414.2 1403.5 1414.2 1403.5 149.8 645.0 645.0 SS1 148.9 645.0 646.2 SS2 κl = 0 . 4 , κq = 1 500 66.2 316.7 707.1 685.7 282.8 274.2 65.9 314.9 314.9 SS1 63.7 314.9 318.1 SS2 1000 150.2 648.3 1414.2 1403.5 565.7 561.4 149.8 645.0 645.0 SS1 148.9 645.6 646.0 SS2 SS1: M 2 < µ , SS2: µ < M 2 - p. 6/12

Production cross-sections Pair production cross-sections at the LHC of W ± χ ± χ 0 H Z H (LHT) and � 1 � 2 (SUSY) SS1: M 2 < µ ; SS2: µ < M 2 10000 10000 LHT LHT SS1 SS1 SS2 SS2 1000 1000 Cross−section (fb) Cross−section (fb) 100 100 10 10 1 1 0.1 0.1 400 600 800 1000 1200 1400 400 600 800 1000 1200 1400 f (GeV) f (GeV) κ q = 1 κ q = 1 . 5 - p. 7/12

Branching fractions versus κ l : LHT and SUSY f = 500 GeV and κq = 1 ; SS1: M 2 < µ & SS2: µ < M 2 1 1 1 ∼ ∼ 0 0 χ χ1 Z −> h A −> h 2 H H ~ 0 ~ 0 χ χ ∼ 0 ∼ 0 ν ν −> h χ2 χ1 2 1 Z −> −> Z e H e H 0.8 0.8 ~ ~ 0.8 0 0 χ χ Z −> e e 2 1 −> Z H H Branching Fraction Branching Fraction Branching Fraction ~ 0 ~ χ2 τ 1 τ −> ~ ~ 0 χ2 −> e eL 0.6 0.6 0.6 χ0 _ ~ ντν ~ −> τ 2 ~ _ ~ χ0 ν e ν e −> 2 0.4 0.4 0.4 SS1 0.2 0.2 0.2 LHT SS2 0 0 0 0.4 0.5 0.6 0.7 0.8 0.9 1 κ 0.8 1 κ 0.4 0.5 0.6 0.7 0.9 0.4 0.5 0.6 κ 0.7 0.8 0.9 1 l l l 1 1 1 χ+ 0 W + ∼ + + ~ ~ ∼ 1 −> χ1 0 χ1 χ W −> W A −> W Η Η 1 χ+ ~ ~ τ τ+ ν e Η 1 −> ν ∼ W −> e + Η χ 1 −> Other modes 0.8 0.8 χ+ 0.8 ~ ν e Η ~e e + Branching Fraction 1 −> ν W −> e Η Branching Fraction Branching Fraction χ+ ~ + ν e ~ 1 −> eL χ+ ~ + ~ 1 −> τ 1 ντ 0.6 0.6 0.6 0.4 0.4 0.4 0.2 0.2 0.2 LHT SS2 SS1 0 0 0 κ 0.4 0.5 0.6 0.7 0.8 0.9 1 0.4 0.5 0.6 0.7 0.8 0.9 1 κ 0.4 0.5 0.6 κ 0.7 0.8 0.9 1 l l l - p. 8/12

Event selection Basic Cuts No jet with p T j > 30 GeV and | η j | < 2 . 7 , p T l > 25 GeV, | η l | < 2 . 5 and ∆ R ll > 0 . 2 E T / > 30 GeV Selection Cuts E T / > 100 GeV m l + l − > 20 GeV | m l + l − − m Z | > 15 GeV | m T ( lE T / ) − m W | > 15 GeV - p. 9/12

3 l + E T / event rates after cuts Number of trilepton events after cuts with integrated luminosity 300 fb − 1 , κ l = 0 . 4 SS1: M 2 < µ ; SS2: µ < M 2 100000 100000 LHT LHT SS1 SS1 SS2 SS2 SM SM 10000 10000 Number of Events Number of Events 1000 1000 100 100 10 10 1 1 400 600 800 1000 1200 1400 400 600 800 1000 1200 1400 f (GeV) f (GeV) κ q = 1 κ q = 1 . 5 - p. 10/12

Trileptons at the LHC: cuts and their efficiency f = 500 GeV, κ q = 1 , κ l = 0 . 4 Integrated luminosity 300 fb − 1 Cuts LHT SS1 SS2 Background No jet with p T j > 30 GeV and | η j | < 2 . 7 , p T l > 25 GeV, | η l | < 2 . 5 and ∆ R ll > 0 . 2 9292.7 1641.4 68.1 20232.5 and E T / > 30 GeV E T / > 100 GeV 7281.2 1187.6 49.6 1599.9 m l ± l ∓ > 20 GeV 7085.4 1137.5 48.1 1596.5 | m l ± l ∓ − m Z | > 15 GeV 4543.9 659.8 18.2 467.1 | m T ( lE T / ) − m W | > 15 GeV 4246.3 606.5 17.0 263.9 - p. 11/12

Summary • LHT trilepton events can be distinguished, at least at the 6 σ level, from either SUSY scenario (SS1 and SS2) even for matching mass spectra for κ l < . 5 . • For higher values of κ l , with higher heavy mirror lepton / slepton masses, the trilepton rates in LHT and SUSY are too low compared to SM background. • Though a LHT-SUSY discrimination is possible for an integrated luminosity of 30 fb − 1 , the information on the mass spectrum might not be sufficient at that stage of the LHC. - p. 12/12