SUSY SEARCHES AT THE TEVATRON Xavier Portell On

SUSY SEARCHES AT THE TEVATRON Xavier Portell (On behalf of CDF and D 0 Collaborations) HCP (Duke, NC) May 2006 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 1

THE TEVATRON p-pbar collider: Chicago 36 x 36 bunches at 396 ns crossing time s = 1. 96 Te. V (Run I 1. 8 Te. V ) Booster CDF Tevatron, CDF and D 0 were highly upgraded in Run II. Great performance: 1. 6 fb-1 delivered DØ Tevatron p source Main Injector 1. 3 fb-1 to tape Data collecting efficiencies ~ 85% SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 2

WHY DO WE NEED SUSY? Q|Boson> = Fermion The SM works very well. . . but there exist some unresolved problems: SUSY: • Mass hierarchy problem The introduction of SUSY have very interesting implications: • Unification Q|Fermion> = Boson ü Solves the hierarchy problem • Dark Matter • Matter-antimatter asymmetry ü Unification of forces at GUT scale ü Provides a Dark Matter candidate ü. . . But SUSY also imply new undiscovered particles. . . SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 3

SUSY BREAKING Symmetry Need to be broken determines phenomenology One of the preferred models: m. SUGRA Ø New superfields in the “hidden” sector Ø Interact gravitationally with MSSM Ø Soft SUSY breaking Ø Only 5 parameters at SUSY scale m 0: common scalar mass at GUT m 1/2: the common gaugino mass at GUT tan : Ratio of Higgs vaccum expectation values A 0: Trilinear coupling Sign( ): Higgs mass term SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 4

R-PARITY Most general SUSY lagrangian Leptonic and Baryonic number violation in the superpotential • l and l’ violate leptonic number and l’’ the baryonic number • ijk denote the families involved New quantum number: Rp=(-1)3(B-L)+2 s ~ 01 e ~ l 121 e 1 2 1 SM particles: Rp=1 Superpartners: Rp=-1 When Rp is conserved: Ø Superpartners are pair produced Ø Lightest SUSY Particle (LSP) SUSY Searches at Tevatron; HCP, Duke, May 2006 Dark Matter candidate! Xavier Portell, 5

Cross Section (pb) T. Plehn, PROSPINO Cross Section (pb) Tevatron: 1. 96 Te. V LHC: 14 Te. V WHY AT THE TEVATRON? increase by 3 -4 orders of magnitude w. r. t. Tevatron. comparable to Tevatron (and with more background). Good prospects for finding SUSY at the Tevatron! 100 events per fb-1 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 6

OUTLINE R P C SQUARKS AND GLUINOS CHARGINOS AND NEUTRALINOS MET+jets 3 -leptons GMSB CHARGINO/NEUTRALINO gg + MET R P V CHARGINO/ NEUTRALINO STOP b-jets and taus INDIRECT 4 -leptons INDIRECT SEARCHES: BS SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 7

OUTLINE SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 8

SQUARKS AND GLUINOS DIRECT SQUARK-GLUINO PRODUCTION: DECAY: Strong interaction: large production expected Missing ET Multiple jets Missing ET (MET) + jets Missing ET Studied an m. SUGRA scenario with first 4 flavors degenerate (sbottom/stop not considered) - Always 3 or more jets Optimized for three cases: - Optimization for three different ranges of gluino masses. 2 -jets (when Mgl>Msq) 3 -jets (when Mgl~Msq) 4 -jets (when Mgl<Msq) Backgrounds are challenging (specially QCD) SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 9

SQUARKS AND GLUINOS Distributions after all cuts for CDF and D 0 agree with data in all cases. 4 -jet optimization Mgl~240 Ge. V/c 2 Mgl~507 Ge. V/c 2 3 -jet optimization CDF background contributions after all the cuts. Mgl~Msq~330 Ge. V/c 2 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 10

SQUARKS AND GLUINOS: LIMITS D 0: 310 pb-1, A 0=0, <0 and tan =3 CDF: 371 pb-1, A 0=0, <0 and tan =5 CDF: Includes theoretical uncertainties when calculating the observed limit D 0: Reduce theoretical cross section by 1 s (more conservative) Mgl > 387 Ge. V/c 2 (when Mgl~Msq) Mgl > 241 Ge. V/c 2 ; Msq > 325 Ge. V/c 2 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 11

3 rd GENERATION SQUARKS SUSY: Predicts left- and right-handed scalar partner eigenstates for each SM fermion As 3 rd generation is heavier, stop and sbottom could be the lightest SUSY particles. Important to have specific analyses for them! SBOTTOM Signatures of 2 or 4 b-jets and MET STOP Depending on the mass: Ø Heavy: A Light stop is preferred (consistent with baryogenesis) Balazs, Carena, Wagner (hep-ph/0403224) Ø Medium: Ø Light: Soft jets (experimental challenge) SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 12

SBOTTOM SELECTION CRITERIA RESULTS ü At least two jets, one b-tagged. ü Good agreement data/MC ü Three different jet/MET thresholds (increasing sbottom mass): ü Exclude sbottom masses up to 200 Ge. V (depending on neutralino mass) ET 1 st > 40 -70 Ge. V ET 2 nd > 15 -40 Ge. V MET > 60 -100 Ge. V ET 1 st > 40 Ge. V ET 2 nd > 15 Ge. V MET > 60 Ge. V (m , m ) = (140, 80) Ge. V/c 2 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 13

STOP ü D 0: 2 different analyses to improve sensitivity: e , ü e analysis: optimized for different Dm= (Mstop – Msneutrino) values ü Missing ET > 15 Ge. V ü Topological cuts The sneutrino usually decays into neutrino and neutralino (MET) Optimization Background Data e (Dm low) 23. 0 3. 1 21 e (Dm high) 40. 7 4. 4 42 2. 9 0. 4 1 Numbers compatible with SM Great improvement with respect to Run I (excluding up to the top mass) SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 14

OUTLINE SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 15

CHARGINOS AND NEUTRALINOS PRODUCTION Mix to form the mass states Always one lepton from + Missing ET Always two leptons from In m. SUGRA: M ~M ~2 M We have always 2 like-sign leptons (one from each superpartner) Clean signature and relatively high cross sections GOLDEN CHANNEL SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 16

CHARGINOS AND NEUTRALINOS The third lepton tends to be very soft tan determines the lepton flavor composition Cuts in lepton PT: PT 1 st~20 Ge. V/c PT 2 nd~10 Ge. V/c taus dominate IMPORTANT ANALYSES VARIETY - 3 leptons (ee+l, e / e+l) Low p. T zone - 2 leptons + track - 2 like-sign (LS) leptons (ee, , e ) Different trigger paths and cut optimizations for e/ and tracks in general SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 17

CHARGINOS AND NEUTRALINOS Ø Minimum p. T for the 2 leading leptons Requirements to reduce SM background Ø Dilepton mass and angle cuts (avoid Z and Drell-Yan) Ø Small jet activity (DY, diboson, conversions. . . ) Ø Missing transverse energy significant Observed/Expected Events All is compatible with SM. . . D 0 t+t et+t CDF SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 18

CHARGINOS AND NEUTRALINOS Low tan and slepton mass degenerate Low tan and no slepton mixing Different luminosities, different number of analyses and slightly different scenarios M > 117 Ge. V/c 2 M > 127 Ge. V/c 2 Results are model dependent (for e. g. with slepton mixing the acceptance is worse and there are no new constraints yet) Ø Beyond LEP (in these scenarios) Ø More luminosity is being added Ø Already implementing some improvements. . . SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 19

OUTLINE SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 20

GMSB: gg+MET In Gauge Mediated Supersymmetry Breaking (GMSB) model the neutralino is the NLSP and the gravitino the LSP (~1 ke. V/c 2). D 0 with 760 pb-1: ü 2 photons (ET>25 Ge. V) NLO ü MET > 45 Ge. V Previous D 0 result (263 pb-1) SM expect: 2. 1 events New D 0 result (760 pb-1) Observation: 1 event Neutralino Chargino New constraints for this process L is the only dimensioned parameter of the GMSB model. SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 21

OUTLINE SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 22

ASSUMPTIONS RPV: CHARGINO/NEUTRALINO ü Only first term of WRPV is considered (protect proton lifetime) ü Charge current universality |l|<0. 135 Ge. V i, j, k denote the leptonic families involved. ü RPV vertex: only in the last decay. ü The decay is inside the detector ü In general: l 121 > l 122 >> l 133 Ø CDF: performing analyses only in l 121 and l 122 Ø D 0: analysing also l 133 (high tan , low m 0) A pair of at least 4 leptons and two neutrinos Also optimizing for 3 leptons to improve acceptance Only one RPV at a time l 121 0 eeee, eee , ee l 122 0 , e, ee Low background just for asking 4 leptons or more! SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 23

RPV: 4 LEPTONS Trilepton Signal Regions Dataset λ 121 : eel Λ 122: l Background 2. 9 ± 0. 8 1. 8 ± 1. 0 Rp. V SUSY 3. 8 ± 0. 4 4. 0 ± 0. 4 Data 5 1 ≥ 4 Signal Region Dataset Signal Background 0. 008 ± 0. 004 Rp. V SUSY 1. 5 ± 0. 3 Data 0 Probability to see >=5 with 2. 9 0. 8 is 17% Very low background! No event found after cuts m 0=1 Te. V ; tanb=5 m 0=100 Ge. V ; tanb=20 Dataset λ 121 : eel l 122: l l 133: eet Background 0. 9 ± 0. 4 ± 0. 1 1. 3 ± 1. 7 m (Ge. V/c 2) 119 118 86 115 m (Ge. V/c 2) 231 229 166 217 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 24

RPV: STOP • 2 b-jets RPV vertex • 1 t hadronic (64. 8%) • 1 t semi-leptonic (35. 2%) CHALLENGE: t identification Jets and leptons t misidentification RPV vertex Used Z tt for hadronic t ID: Eff ~ 56% Expected events: 2. 2 Observed events: 2 (1 e + 1 ) New mass limits are obtained with 322 pb-1 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 25

OUTLINE SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 26

INDIRECT SEARCHES: BS SM: Bs-> is heavily suppressed: SUSY: BR enhancement by 1 -3 orders of magn. (Buchalla & Buras, Misiak & Urban) New CDF result: 780 (Babu, Kolda: hep-ph/9909476+ many more) pb-1 Using B+ J/ K+ for normalization R. Dermisek et al. hep-ph/0507233 (2005) High resolution! s(M ) ~ 0. 23 Me. V Found 1 event; expected background 0. 9 0. 3 New limits at 95% C. L: BR(Bs ) < 1. 0· 10 -7 SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 27

DISCLAIMER Due to time constraints I couldn’t cover all the analyses for both detectors. Some of the most interesting analyses, not covered here, are: Ø Stopped gluinos (split SUSY) (350 pb-1) Ø Long lived charginos (AMSB) (380 pb-1) This topic will be covered in the next talk Ø Resonant slepton production (RPV) (380 pb-1) Ø sneutrino e (RPV) (344 pb-1) You can find them all at the CDF or D 0 webpages: http: //www-cdf. fnal. gov/physics/exotic. html http: //www-d 0. fnal. gov/Run 2 Physics/WWW/results/np. htm SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 28

SUMMARY ØTevatron and detectors are performing very well: ü 1. 6 fb-1 delivered (collected: 1. 3 fb-1) ü Upgrades have been performed during this shutdown ü This week Tevatron will start again fully operational and 2 fb-1 benchmark is getting closer. Ø Plenty of SUSY analyses going on at CDF/D 0 detectors. They are being improved with the addition of new data. Ø No SUSY particles have been discovered yet but both direct and indirect analyses are constraining the SUSY parameter space. Tevatron will keep constraining the SUSY parameters until the LHC era. . . and perhaps a surprise is found! SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 29

BACKUPS SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 30

Different 3 -Leptons Scenarios In Standard m. Sugra the BR into taus is enhanced smaller acceptance SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 31

CDF 3 -Leptons Analyses CHANNEL LUM TRIGGER PATH e e , e , 710 High p. T Single Lepton + e/ 750 High p. T Single Lepton ee + e/ 350 High p. T Single Lepton + e/ 310 Low p. T Dilepton ee + track 610 Low p. T Dilepton No third lepton requirement => Higher acceptance Use e/mu only =>Very small backgrounds Sensitive to taus as 3 rd lepton => Keeps acceptance at high tan SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 32

-SUSY • DATA N events/2 Ge. V/c 2 §Drell-Yan §WZ §ZZ §ttbar §Fakes MET CDF 3 -Leptons Control Regions ? ? SIGNAL REGION 15 106 L=607 pb-1 §Drell-Yan §Dibosons §ZZ §bbbar - SUSY • DATA 76 M( ) MET (Ge. V) Dielectron Invariant Mass(Ge. V/c 2) LS-dilepton analysis has additional Control Regions to test conversion removal Dimuon PT(Ge. V/c) SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 33

CDF 3 -electron Event SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 34

3 -LEPTONS: PROJECTIONS SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 35

Bs : PROJECTIONS SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 36

SQUARKS/GLUINOS: FUTURE SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 37

SQUARKS AND GLUINOS SUSY Searches at Tevatron; HCP, Duke, May 2006 Xavier Portell, 38