Slepton, Charginos and Neutralinos at the LHC Shufang Su U. of Arizona, UC Irvine S. Su In collaboration with J. Eckel, W. Shepherd, arxiv:.xxxx; T. Han, S. Padhi, arxiv:.xxxx;
Outline Limitation of current LHC SUSY searches Current exp search limits on MSSM EW sector MSSM electroweak sector Neutralinos/Charginos: production and decay Two analyses: Gauginos and Higgsinos (in slepton decoupling limit) Sleptons via gaugino decays Conclusion S. Su
Current LHC SUSY searches: limitations 3 =<ST ) (GeV/c m / 7 6 5 4 CMS Preliminary & % = LSP Limits q ~ (5)GeV Limits tan# =, A q~ ()GeV q ~ (75)GeV Lepton =, µ > MT SS Dilepton s = 7 TeV, Ldt =. fb! T CDF g~, ~ q, tan#=5, µ< D g~, ~ q, tan#=3, µ< ± LEP % $ ~ ± LEP l g ~ (5)GeV Jets+MHT g ~ ()GeV 3 OS Dilepton g ~ (75)GeV!#$%&'() *'+',./ +'**'% ' q ~ (5)GeV g ~ (5)GeV 4 6 8 m (GeV/c ) =<ST S. Su 3
Current LHC SUSY searches: limitations 4 =<ST msugra mm/ plane? ) (GeV/c m / 7 6 5 3 CMS Preliminary q ~ (5)GeV tan# =, A q~ ()GeV 4 Lepton large HT cuts: less sensitive to light particles SS Dilepton & % = LSP Limits Limits starting from gluino/squark production q ~ (75)GeV =, µ > MT OS Dilepton s = 7 TeV, Ldt =. fb! T CDF g~, ~ q, tan#=5, µ< D g~, ~ q, tan#=3, µ< ± LEP % $ ~ ± LEP l g ~ (5)GeV Jets+MHT g ~ ()GeV g ~ (75)GeV!#$%&'() *'+',./ +'**'% ' q ~ (5)GeV g ~ (5)GeV 4 6 8 m (GeV/c ) =<ST S. Su 4
LHC vs. Tevatron 5 ) (GeV/c m / 4 35 3 5 CMS $# = LSP 95% C.L. Limits: CMS LO observed CMS NLO observed CMS NLO expected ± % CMS NLO expected ± % L int = 35 pb, q ~ (65)GeV/c tan! = 3, A q ~ (5)GeV/c D g~, ~ q, LEP # ~ ± LEP l ± D #, # 5 5 5 5 3 m s = 7 TeV ± g ~ (65)GeV/c =, µ < µ > g ~ (5)GeV/c (GeV/c ) % $ B( # 3l) (pb) 9 8 7 6 5 4 3 CMS = 35 pb, s = 7 TeV LEP direct Limit D Limiṯ L=.3fb L int 4 6 8 tan&=3, A =, µ>, 95% C.L. Limits: CMS observed CMS expected ± % CMS expected ± % Theory % NLO $ B( # 3l) m! ± m =6 GeV/c (GeV/c ) RunII: EW χ ± χ production LHC: gluino/squark pair production not a direct limit on mχ ± derived from mgluino not msugra? colored particles are heavy? gaugino masses do not unify? very likely likely S. Su 5 likely
Motivation 6 Exploring LHC reach for the electroweak sector of MSSM gauginos, Higgsinos and sleptons. DM connection neutralinos: DM candidate sleptons: relevant for DM annihilation process Superpartners of gauge bosons, Higgses, and leptons suffer from small electroweak production more work needs to be done regarding collider searches current SUSY search strategy is not sensitive to lighter EW interacting particles (large HT cuts reduce the signal efficiency) Colored superparticle might be very heavy no indication from current LHC search EW sector (+stop/sbottoms) might be the only particles accessible at the LHC Connection to Lepton Collider S. Su 6
Current limits: neutralino/chargino 7 5 4 canonical case tan$= #= GeV ADLO!s! 6.5 GeV degenerate case 7 8 9 ADLO preliminary Gaugino M# ~! 5 GeV mχ > 47/5 GeV (CMSSM, msugra) No mass limit in general M# + (GeV) 3 99 Excluded at 95 C.L. 4 6 8 M ~ (GeV) mχ ± > 3.5 GeV for msnue > 3 GeV LEPSUSYWG/3. M (GeV) expected limit 7 8 9 M! ~ + (GeV) mχ ± > 9.9 /9.4 GeV LEPSUSYWG/4. M! (GeV/c ) 8 6 4 #s = 838 GeV ADLO + ẽ RẽR + R R + R R M l! M! R mse > 99.6 GeV, msmu > 94.9 GeV, mstau > 85.9 (85.) GeV Observed Expected Excluded at 95# CL (= GeV/c, tan$=.5) 5 6 7 8 9 M l (GeV/c ) R S. Su 7 LEPSUSYWG/4.
Current limits: neutralino/chargino 8 M# + (GeV) 5 4 3 99 canonical case tan$= ADLO #= GeV!s! 6.5 GeV Excluded at 95 C.L. 4 6 8 M ~ (GeV) mχ ± > 3.5 GeV for msnue > 3 GeV LEPSUSYWG/3. M (GeV) degenerate case 7 8 9 ADLO preliminary Gaugino M# ~! 5 GeV expected limit Have at least one of these assumptions: gaugino mass unification: M= (5/3) tan θw M = / M sfermion mass unification decouple sfermions msugra particular benchmark point 7 8 9 M! ~ + (GeV)... mχ ± > 9.9 /9.4 GeV LEPSUSYWG/4. S. Su 8 LEPSUSYWG/4. M! (GeV/c ) 8 6 4 mχ > 47/5 GeV (CMSSM, msugra) No mass limit in general #s = 838 GeV ADLO + ẽ RẽR + R R + R R M l! M! R mse > 99.6 GeV, msmu > 94.9 GeV, mstau > 85.9 (85.) GeV Observed Expected Excluded at 95# CL (= GeV/c, tan$=.5) 5 6 7 8 9 M l (GeV/c ) R
MSSM Electroweak sector 9 Gauginos and Higgsinos ~ ~ Neutral ones: Bino, Wino, Hu, Hd ~ charged ones: Winos, Hu + ~, Hd Neutralinos and charginos Parameters: M, M, µ, tanβ Sleptons: sll, slr, three generations No flavor mixing No LR mixing for the st, nd generations sel, ser, smul, smur, stau, stau Parameters: MslL, MslR, (LR for stau? universality?) S. Su 9
Order of M, M and µ Bino LSP M < M, µ Wino LSP M < M, µ Higgsino LSP µ < M, M Bino Wino Higgsino e.g.: sugra, CMSSM, gaugino mass unification,... canonical case e.g.: AMSB,... Chen et. al., hepph/953 Moroi et. al., hepph/9945 Gherghetta et. al., hepph/994378 Bear et. al., hepph/773 Moroi et. al., ArXiv: 8.375 e.g.: Higgsinoworld,... Baer, Barger and Huang, ArXiv: 7.558 S. Su
Bino LSP case light wino M < M < µ light Higgsino M < µ < M Higgsino Wino Wino Higgsino Bino χ χ ± χ χ ± Bino S. Su
Productions: Neutralinos and Charginos light wino M < M < µ! (pb) tan =,! = TeV M = GeV, LO M = GeV, NLO M = 3 GeV, LO M = 3 GeV, NLO! (pb) 3 tan# =, = TeV, M = GeV χ + χ χ ± χ! +!! 3 3 3 3 3 4 5 3 6 3 4 5 6 7 M (GeV) 3 4 5 6 7 M (GeV) cross section has little dependence on M S. Su
χ ± decay with decoupled slepton 3! light wino M < M < µ!! (?!! (@@ $ onshell h! # #!! '( χ!! (9# 9./(()!!!!! (# 34''.5!!!!! ',,!! ')!! '** offshell W* onshell W!! '##!! '!!# χ ±! # $ % & ' # (()*+,!!#!!! '$! '++! # $ % & # ''./ offshell Z* onshell Z S. Su 3
LHC searches 4 Collider signatures jets + MET l + jets + MET OSl + jets + MET SSl + jets + MET: include trilepton Validation of MonteCarlo: compare with CMS analyses for Luminosity up to fb LM, event field from CMS single lepton study: 8.7 ±. Our simulation: 8.77 Upper limit at 95% CL on event yield using existing CMS searches L observed BG 95%CL jets + MET. fb 8 channels......... l + jets + MET 36 pb 9 7 ± 7. 4 OSl + jets + MET.98 fb high MET 8 4. ±.3 high HT 4 5. ±.7 5.3 SSl + jets + MET.98 fb 7 channels......... S. Su 4
95% CL upper limit on cross sections 5 SSl+jets + MET M (GeV) 9 8 # BR (pb) SS / dileptons (MET >, H T tan! =, µ = TeV > 8 GeV) 9 8 M (GeV) 9 8 # BR (pb) SS / dileptons (MET > 5, H T tan! =, µ = TeV > 4 GeV) 9 8 7 7 7 7 6 6 6 6 5 5 5 5 4 4 4 4 3 3 3 3 3 4 5 6 7 8 9 M (GeV) 3 4 5 6 7 8 9 M (GeV) low HT cut has better reach! probably best exclusion channel among four searches S. Su 5
95% CL upper limit on cross sections 6 SSl+jets + MET M (GeV) 9 8 7 # BR (pb) SS / dileptons (MET >, H T tan! =, µ = TeV > 8 GeV) 9 8 7! (pb) tan =,! = TeV M = GeV, LO M = GeV, NLO M = 3 GeV, LO M = 3 GeV, NLO 6 6 5 5 4 4 3 3 3 3 4 5 6 7 8 9 M (GeV) 3 4 5 6 7 M (GeV) low HT cut has better reach! probably best exclusion channel among four searches S. Su 6
M (GeV) 95% CL upper limit on cross sections SSl+jets + MET 9 8 # BR (pb) SS / dileptons (MET >, H T tan! =, µ = TeV > 8 GeV) 9 8! (pb) tan =,! = TeV 7 M = GeV, LO M = GeV, NLO M = 3 GeV, LO M = 3 GeV, NLO 7 7 6 6 upper limit fb 5 9 5 SS / dileptons (MET >, H 3 > 8 GeV) 4 T 5 6 9 7 4 8 4tan! =, µ = TeV 8 3 7 3 Nj requirements 7 6 too strong. 6 5 need jet veto. 5 3 4 5 6 7 8 9 4 4 M (GeV) low HT cut has better reach! probably best exclusion channel among four searches M (GeV) 3 3 3 M (GeV) S. Su 7 M (GeV) 3 4 5 6 7 8 9
Reach in MM and Mmu plane 8 with optimized cuts... M (GeV) 9 8 7 $# Acceptance fb T : H T (GeV) > 875 tan! =, µ = TeV 5 fb M (GeV) 9 8 7 $# Acceptance T : H T (GeV) > 875 tan! =, M = TeV 6 6 5 4 3 5 Results will come 4 (very soon)... 3 3 4 5 6 7 8 9 M (GeV) 3 4 5 6 7 8 9 µ S. Su 8
Slepton studies 9 DrellYan production cross section small 3 s = 4 TeV SM BG large: W, WW, WZ, ttbar, etc. % (pb)!! e ~ ~ R e R e ~ ~ L e L = solid $ ~ ~ L $ L = dotdash W ± # ~ e ~ L $ L usually done in msugra framework Limited reach: L=3 fb, GeV for slr, 3 GeV for sll!3!4 3 4 5 ~ (GeV) m l Y.M.Andreev, S.I.Bityukov, N.V.Krasnikov, hepph/49; H.Baer, C.h.Chen, F.Paige, X.Tata,hepph/ 9348, hepph/95383 S. Su 9
Slepton from Neutralino/Chargino decay For MseL < M, light Wino case larger cross sections!! 4 TeV l l +!*+**#!! *## /***+/!!!! χ χ + l + l ν ν χ χ!!#! # $ % & ' ( ) # **+,./ S. Su
Slepton from Neutralino/Chargino decay large branching ratios 35 M=5 GeV, M=4 GeV trilepton + MET signal, less SM BG Events/.5 GeV/ fb 4 3 5.7 / 97 P 9. P 8.7 P3.9 5 5 M ll (GeV) 5 5 5 3 35 4 m slepton (GeV) distinctive triangle shape for mll obvioustoeye spectral shape How to use it to enhance our signal significance? enhanced by only plotting the signal How about BG? : l + Bachacou, l mass S. Su distribution Hinchliffe, showing and Paige, the χhepph/99758 MINUIT fit using PAW. m cutoff (GeV) 3 5 5 5 m (m ) cutoff = m m χ χ m m χ mz
Cross section reach given mcut, marginalizing over other fitting parameters Nsig required for 5 sigma required sigma*br*acc l l + 4 TeV fb X X Y Y Z Z l + ν Model independent result! Can be applied to other model with similar topology background fitting: any process give a Z peak results only sensitive to mcut given model mx, my, mz mcut sigma*br*acc S. Su
MSSM Slepton: 4 TeV Reach 3 Apply to MSSM case, slepton from χ ± χ decay Luminosity [fb ] Slepton Mass [GeV] 6 5 L=3 fb, reach sll up to 5 GeV for M up to 65 GeV. 4 3 3 4 5 6 7 Wino Mass [GeV] S. Su 3
Conclusions 4 LHC has great reach for colored particles, but more studies needed to explore LHC potential for EW particles. Current LHC search already set strong bounds (TeV) on the mass of colored object, however, the search strategy is not optimized for EW particles. Existing study on EW particles make simple assumptions, e.g., msugra or gaugino mass unification relation MSSM EW sector: neutralinos, charginos and sleptons with general parametrization S. Su 4
Conclusions 5 Neutralinos/charginos: light wino and light Higgsino cases decay pattern depends on the slepton masses LHC reach of neutralinos/charginos with decoupled slepton MM, Mµ light slepton: slepton via neutralino/chargino decay utilize the triangle shape in mll distribution model independent approach: results can be applied to other models, and various mass spectrum MSSM: 4 TeV with 3 fb, M up to 65 GeV, MseL up to 5 GeV S. Su 5
Regions to be explored 6 neutralino/chargino reach for slepton heavier than χ /χ ±, but accessible through offshell slepton decay lepton rich final state, but no triangle feature slepton DY, direct decay, for nonsugra spectrum slepton DY with cascade decay... Stay tuned... S. Su 6