Some Thoughts on What Else to Trigger with the FTK

Transcription

1 Some Thoughts on What Else to Trigger with the FTK Beate Heinemann, University of Liverpool Sbottom Stop Bs->mumu Other rare B decays Summary ATLAS FTK Meeting, 04/21/2005 Disclaimer: these are just a few ideas and I have not enough information for anything quantitative

2 3rd generation Squark Production 3rd generation squarks lightest: Stop lightest due to large m(top) Sbottom light if tanβ large Production: direct or via gluino decay Gluino decay is one of the golden channels Direct stop Direct sbottom Gluino decay 04/21/05 B. Heinemann, ATLAS FTK Meeting 2

3 Trigger Current ATLAS trigger for L=2x10 33 cm -2 s -1 : L1: Etjet>60GeV, MEt>60 GeV HLT: Etjet>70 GeV, Met>70 GeV Can we get more phase space by lowering thresholds but adding b-tag? Main BG is QCD and thus not flavour democratic => rate reduction 04/21/05 B. Heinemann, ATLAS FTK Meeting 3

4 Would be nice to study at ATLAS: are there any such plots? 04/21/05 B. Heinemann, ATLAS FTK Meeting 4

5 Light Stop-Quark: Motivation If stop is light: decay only via t->cχ 1 0 (if other decays closed kinematically) E.g. consistent with relic density from WMAP data hep-ph/ (Balazs, Carena, Wagner) Ω CDM = M(t)-M(χ 10 ) GeV CDF search for 2 charmjets and large E t: E t (jet)>35, 25 GeV E t >55 GeV 04/21/05 B. Heinemann, ATLAS FTK Meeting 5

6 Kinematics at Tevatron 2 jets and large Met Trigger cuts rather harsh Don t know kinematics at ATLAS => will check in MC This is an easy squark to find if gluino light enough: pp->gg->tttt->wwbbccχχ ~ ~ ~ ~ ~~ MEt Stop MC LHC trigger cut Jet Et 04/21/05 B. Heinemann, ATLAS FTK Meeting 6

7 Indirect Search: B s ->µµ BR(B s ->µµ): SM: 3.5 x 10-9 (G. Buchalla, A. Buras Nucl. Phys. B398, 285) SUSY: tan 6 β CDF Selection: 2 muons: pt>2 GeV displaced vertex Topological cuts ATLAS trigger: L1: 2µ with pt>6 GeV HLT: 2µ with pt>10 GeV ATLAS yield (Sebastien Viret): From ATLAS-PHYS About 1 event per 1 fb -1 if SM BR Would benefit A LOT from FTK I think Would like to investigate further cτ 04/21/05 B. Heinemann, ATLAS FTK Meeting 7

8 Bs->µµ vs DM cross section (Baek et al.: hep-ph ) Probe SUSY parameter space consistent with WMAP data: msugra: just touching SO10-models (Dermisek et al. hep/ph ) => already constraining Bs->µµ complementary to direct DM detection experiments M 0 =300 GeV, A 0 =0 CDF CDF 04/21/05 B. Heinemann, ATLAS FTK Meeting 8

9 More Rare B-Decays Di-muonic decays (see ATLAS-PHYS ): B d ->K *0 µµ B s ->φµµ B d ->ρµµ Large samples needed since new physics sensitive to an asymmetry A FB : I read that but am not really an expert But probably enhancing statistics is good ATLAS and CMS competitive with LHCb Sinead is measuring B s ->φµµ in CDF: may be able to do a quick study 04/21/05 B. Heinemann, ATLAS FTK Meeting 9

10 Summary Improve sensitivity to sbottom and stop: Could be useful in certain regions of parameter space Could lower thresholds for b-jet based triggers But maybe acceptance of current MEt cut sufficient Improve sensitivity to B s ->µµ BR: Very interesting as SM value will probably be probed probes large regions of MSSM parameter space ATLAS and CMS competitive with LHCb Other rare B-decays also interesting 04/21/05 B. Heinemann, ATLAS FTK Meeting 10

11 MSSM Higgs In MSSM the bba Yukawa coupling grows like tan 2 β: Larger cross sections Better discovery potential than SM Search for final states: A+b+X->bbb+X A+X >ττ+x LO diagrams S. Willenbrock 04/21/05 B. Heinemann, ATLAS FTK Meeting 11

12 MSSM Higgs: A -> ττ τ s are tough! Select di-τ events: 1 lepton from τ lνν 1 hadronic τ-decay (narrow jet) Efficiency 1% Background: mostly Z->ττ 04/21/05 B. Heinemann, ATLAS FTK Meeting 12

13 MSSM Higgs A-> ττ Fit visible mass: from leptons, tau s and E t Limit on σxbr 10-2 pb Interpretation soon in tanβ vs m A plane 04/21/05 B. Heinemann, ATLAS FTK Meeting 13

14 Light Stop-Quark: Result Data consistent with background estimate Observed: 11 Expected: Main background: Z+ jj -> vvjj W+jj -> τvjj Systematic error large: 30% ISR/FSR: 23% Stop cross section: 16% Not quite yet sensitive to MSugra cross section 04/21/05 B. Heinemann, ATLAS FTK Meeting 14

15 Stop Candidate event 04/21/05 B. Heinemann, ATLAS FTK Meeting 15

16 B s ->µµ 1x10-7 1x10-8 expected observed BR@95% C.L. D0 4.3±1.2 4 <3.5x10-7 CDF 1.4±0.2 0 <2.0X /21/05 B. Heinemann, ATLAS FTK Meeting 16

17 High tanβ scenario: Sbottom could be light This analysis: CDF Result Gluino rather light: GeV ~ ~ BR(g->bb)~100% assumed Spectacular signature: 4 b-quarks + E t Require b-jets and E t >80 GeV Expect:2.6±0.7 Observe: 4 Exclude new parameter space in gluino vs. sbottom mass plane 04/21/05 B. Heinemann, ATLAS FTK Meeting 17

18 Sbottom Production Cross Sections at Tevatron Gluino cross section larger if gluino mass low enough However, unclear whether that is the case Don t have LHC cross sections => will calculate 04/21/05 B. Heinemann, ATLAS FTK Meeting 18

19 04/21/05 B. Heinemann, ATLAS FTK Meeting 19