Probing Supersymmetric Connection with Dark Matter

Transcription

1 From サイエンス 82 Probing Supersymmetric Connection with Dark Matter Taken from Science, 1982 Teruki Kamon Department of Physics Texas A&M University November 3, 2005 Physics Colloquium, Texas Tech University November 3, 2005 Probing Supersymmetric Connection with Dark Matter 1 1

2 Abstract Supersymmetry, a leading theory beyond the Standard Model of particle physics, is naturally connected to explain the cold dark matter of the universe. A few key experimental signatures are proposed to probe the supersymmetric connection to the dark matter at hadron-hadron and electronpositron colliders. I will discuss the theoretical motivation and its experimental signatures at the Tevatron, the Large Hadron Collider, and an International Linear Collider. November 3, 2005 Probing Supersymmetric Connection with Dark Matter 2

3 Outline Standard Model (SM) Supersymmetry (SUSY) Supergraviy (SUGRA) + Cosmic Connection Three Colliders The Best Signature at the Tevatron The Best Signature at an ILC The Best Signature at the LHC Summary November 3, 2005 Probing Supersymmetric Connection with Dark Matter 3

4 November 3, 2005 Probing Supersymmetric Connection with Dark Matter 4

5 Standard Model (SM) is a theory of elementary particles and its fundamental interactions. 6 quarks, 6 leptons and gauge particles November 3, 2005 Probing Supersymmetric Connection with Dark Matter 5

6 SM at Low Energy can explain the neutron decay (weak interaction). d time W u e ν e November 3, 2005 Probing Supersymmetric Connection with Dark Matter 6

7 SM at High Energy helps the discovery of the top quark in t be + ν e t time b e W + + ν e November 3, 2005 Probing Supersymmetric Connection with Dark Matter 7 t b e + W + ν e

8 Very Successful at E~100 GeV Predictions were tested in various experiments: Remarkable accuracy: B.S. Neutral CERN SPS (400 GeV p) M.S. W/Z discovery CERN SppS (540 GeV pp ) Ph.D. Top Fermilab Tevatron (1.8 TeV pp ) M M exp Z theory Z = = ± ± Explains most of the data! GeV GeV What happens at higher energy? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 8

9 Running Coupling e.g., QCD 2 12π α s ( Q ) = 2 2 (11n 2n ) log( Q / Λ ) color flavor Introduction to High Energy Physics by D. H. Perkins n f = 6 (quark flavors); n c = 3 (colors) The Nobel Prize in Physics 2004 α s Q 2 (GeV 2 ) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 9

10 3 Couplings at Higher Energy (Strength of Force) 1 1/α i (E) 1/α 1 1/α 2 1/α 3 log 10 (Energy) SM Three gauge couplings do do not not meet at at a single point. We need a theory which goes to to a higher scale. The SM works very well at ~100 GeV. The SM works very well at ~100 GeV. Grand Unified Theory Supersymmetry November 3, 2005 Probing Supersymmetric Connection with Dark Matter 10

11 (SUSY) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 11

12 Supersymmetrized SM The fundamental law(s) of nature is hypothesized to be symmetric between bosons and fermions. Fermion (S = ½ ) Boson (S = 0 or 1) Have they been observed? Not yet. November 3, 2005 Probing Supersymmetric Connection with Dark Matter 12

13 Feynman Diagrams for SUSY Decays SUSY partner of W boson: chargino SUSY partner of τ lepton: stau SUSY partner of Z boson: neutralino Lightest neutralinos are always in the final state! This neutralino is the dark matter candidate!! November 3, 2005 Probing Supersymmetric Connection with Dark Matter 13

14 To be (SUSY), Not to be It doubles the number of particles in the nature. This is not the first time. The electron-positron (particle-antiparticle) symmetry was predicted before the discovery of positron by P.A.M. Dirac: r r H ψ = ( α p + β m)ψ What do we gain if the theory is supersymmetric? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 14

15 Sign of SUSY Unification 1/α 1 SM 1/α 1 SM + SUSY 1/α i (E) 1/α 2 1/α 3 1/α 2 1/α 3 1/α GUT log 10 (Energy) M SUSY 2 SUSY ~ GeV/c 2 log 10 (Energy) and two (and only two) Higgs doublets What else? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 15

16 Cosmic Connection Astrophysics CDM = Neutralino ( ) SUSY χ ~ 1 0 CDM = The matter which is present without any electromagnetic interaction. To explain the amount of the CDM, there must be another SUSY particle whose mass must be closer to the neutralino. (see the next slide.) Is it possible to observe these features in other experiments (e.g., Dark matter detection, Collider experiments)? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 16

17 (msugra at large tanβ) R. Arnowitt, B. Dutta, T. Kamon, M. Tanaka, Phys. Lett. B538, 121 (2002) R. Arnowitt, B. Dutta, B. Hu, hep-ph/ (talk at BEYOND '03) A. Lahanas, D.V. Nanopoulos, Phys. Lett. B568, 55 (2003) J. Ellis et al., Phys. Lett. B565,176 (2003) H. Baer et al., JHEP 0207, 050 (2002) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 17

18 Minimal Supergravity (msugra) SUSY model with two Higgs fields (H u and H d ) in the framework of unification: 1) All SUSY masses are unified at the grand unified scale. m m 1/2 0 for gaugino for squarks masses and sleptons 2) Two more parameters: tanβ A 0 November 3, 2005 Probing Supersymmetric Connection with Dark Matter 18

19 Power of tanβ I always want you to be slimmer than your cousin SELECTRON. τ ~ e ~ This tanβ also controls the SUSY masses, especially, the 3 rd generation SUSY particles, ~ such as. t, b ~ and τ ~ November 3, 2005 Probing Supersymmetric Connection with Dark Matter 19

20 November 3, 2005 Probing Supersymmetric Connection with Dark Matter 20 Neutralino = CDM Neutralino = CDM ( ) 2 1 CDM Ω 20 2 M / e 0 χ ~ 1 τ ~ M ~ M ~ M χ τ msugra naturally provides a lighter stau.

21 Cosmologically Allowed Region Mass of Squarks and Sleptons Excluded Higgs Mass (M h ) Branching Ratio b sγ Magnetic Moment of Muon Mass of Gauginos CDM allowed region November 3, 2005 Probing Supersymmetric Connection with Dark Matter 21

22 Mass of Squarks and Sleptons Small and Large tanβ Mass of Gauginos narrow co-annihilation corridor B. Dutta What are the signals from the narrow co-annihilation corridor? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 22

23 Mass Relations at Large tanβ Small M ~ ~ τ m τ m χ 0 1 M M ~ τ M ~ 0 = 5 ~ 1 χ 1 15 GeV CDM candidate What are the signals at colliders? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 23

24 How can we test the models at 3 colliders: 1) Tevatron (2 TeV pp ) 2) LHC (14 TeV pp) 3) ILC (500 or 800 GeV e + e ) Question November 3, 2005 Probing Supersymmetric Connection with Dark Matter 24

25 TEV LHC ILC What are the roles of these machines? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 25

26 E Tevatron HERA LEP2 TEV LHC ILC LHC ILC Precision November 3, 2005 Probing Supersymmetric Connection with Dark Matter 26

27 E Tevatron HERA LEP2 TEV LHC ILC LHC ILC Precision November 3, 2005 Probing Supersymmetric Connection with Dark Matter 27

28 E Tevatron HERA LEP2 TEV LHC ILC LHC ILC SHE IS SUPERSYMMETRIC! Precision November 3, 2005 Probing Supersymmetric Connection with Dark Matter 28

29 How to Analyze the Data? Quarks. Neutrons. Mesons. All those particles You can t see. That s what drove me to drink. But now I can see them! A little bit more scientific way? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 29

30 20 years ago First Proton-Antiproton Collisions Pencil and ruler? We are doing in much better way! November 3, 2005 Probing Supersymmetric Connection with Dark Matter 30

31 (B s µ + µ ) V. Krutelyov, R. Arnowitt, B. Dutta, T. Kamon, P. McIntyre, Y. Santoso, Phys. Lett. B505, 161 (2001) R. Arnowitt, B. Dutta, T. Kamon, M. Tanaka, Phys. Lett. B538, 121 (2002) CDF Collaboration, Phys. Rev. Lett. 93, (2004) CDF Collaboration, to appear in Phys. Rev. Lett. (2005) V. Krutelyov, Ph.D. Thesis, Texas A&M University (unpublished) (2005) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 31

32 Tevatron s = 1.96 TeV Proton (p) _ Antiproton (p) CDF DØ November 3, 2005 Probing Supersymmetric Connection with Dark Matter 32

33 Rare Decay B s(d) µ + µ B 9 SM = B SUSY (tanβ ) Within the SM, we will not see any events even with 100 x collisions. The B s µ + µ event would look like this. In the SUSY models (large tanβ), the decay can be enhanced by up to 1,000. November 3, 2005 Probing Supersymmetric Connection with Dark Matter 33

34 1 st Round Analysis 170 pb 1 ~ 8.5 x collisions CDF Collaboration, Phys. Rev. Lett. 93, (2004) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 34

35 2nd Round Analysis Powerful Likelihood method to reduce BG events with LH > 0.99 N BG = 1.47± 0.18 N obs = pb 1 ~ 18 x collisions ±60 MeV/c 2 (2.5σ) CDF Collaboration, to appear in Phys. Rev. Lett. (2005) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 35

36 Prospects TEVATRON Tevatron Limit 1.6x10 7 CDF : 364 pb 1 DØ : 300 pb 1 CDF analyses are evolving/ improving with more data. x? Tevatron Limit 2-3x10 8? CDF : 1000 pb 1 DØ : 1000 pb pb 1 ~ 50 x collisions November 3, 2005 Probing Supersymmetric Connection with Dark Matter 36

37 B (B s µµ µµ) ) and Cosmological Connection TeV LHC/ILC Cosmology Can we see the SUSY co-annihilation signals at LHC and ILC? M~ g ~ 1400 GeV/c 2 Competitive to the LHC November 3, 2005 Probing Supersymmetric Connection with Dark Matter 37

38 (two taus) V. Khotilovich, R. Arnowitt, B. Dutta, T. Kamon, Phys. Lett. B618, 182 (2005) November 3, 2005 Probing Supersymmetric Connection with Dark Matter 38

39 ILC November 3, 2005 Probing Supersymmetric Connection with Dark Matter 39

40 ILC How about the LHC? Can we see the signal? Can we measure M? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 40

41 (two taus + jets + missing energy) R. Arnowitt, A. Arusano, B. Dutta., T. Kamon, V. Khotilovich, N. Kolev, P. Simeon, D. Toback, P. Wagner in progress November 3, 2005 Probing Supersymmetric Connection with Dark Matter 41

42 TAMU is joining CMS at the LHC. C.M. Energy = 14 TeV New Energy Frontier 2 large detectors: CMS and ATLAS Performance: Bound to find or exclude Higgs Discover or almost exclude SUSY November 3, 2005 Probing Supersymmetric Connection with Dark Matter 42

43 ILC vs. LHC ILC LHC November 3, 2005 Probing Supersymmetric Connection with Dark Matter 43

44 The event might look like this CDF highest H T Event E T1 = 172 GeV E T2 = 153 GeV E T4 = 65 GeV + 3 x / E T = 223 GeV E T3 = 80 GeV H T = E T1 + E T2 + E T3 = 404 GeV τ November 3, 2005 Probing Supersymmetric Connection with Dark Matter 44

45 Practice with CDF pb 1 Consistent with the SM expectation Preparing PRL 2 τ + 2 jet Fig. 1: Event display of one of two events November 3, 2005 Probing Supersymmetric Connection with Dark Matter 45

46 LHC Simulation/CDF Experience Expanding the analysis to SUSY signals at the LHC. So far, preliminary results were presented at: Mitchell Observational Cosmology 2004 (College Station, TX) DARK 2004 (College Station, TX) SUSY 2005 (Durham, UK) Finalizing the results. Homework: Can we see the signal? Can we measure M? November 3, 2005 Probing Supersymmetric Connection with Dark Matter 46

47 Today s s Signal, Tomorrow s s BG Today s signal = Cosmic Connection Ten years ago, the top quark was discovered. We were excited. But the top events will be a serious background source for the SUSY searches at the LHC. The CDF data will make us smarter (hopefully) to learn how to suppress the SM background event to maximize the from the LHC. November 3, 2005 Probing Supersymmetric Connection with Dark Matter 47

48 November 3, 2005 Probing Supersymmetric Connection with Dark Matter 48

49 Summary Objective = Probing the models at the grand unified scale with cosmic connections Tevatron - provides an important lesson on how to handle the hadron-hadron collider data. LHC at CERN (2007) will tell us the existence of Higgs and SUSY particles. The TAMU group is joining the CMS. ILC will be the machine to make precise measurements on the Higgs and SUSY. November 3, 2005 Probing Supersymmetric Connection with Dark Matter 49

50 Summary (cont d) Healthy collaboration with theorists. November 3, 2005 Probing Supersymmetric Connection with Dark Matter 50

51 E Road Map to Unified Theory String Theory SUSY GUT x November 3, 2005 Probing Supersymmetric Connection with Dark Matter 51

52 Faculty Members and Research Areas EXPERIMENT [Collider Physics - CDF, CMS, International Linear Collider] T. Kamon, P. McIntyre, D. Toback [Neutrino Physics - MINOS, NOνA] R. Webb [Dark Matter - ZEPLIN] J. White THEORY [Phenomenology] R. Allen, R. Arnowitt, R. Bryan, B. Dutta, D. Nanopoulos [String Theory] K. Becker, M. Becker, D. Nanopoulos, C. Pope, E. Sezgin November 3, 2005 Probing Supersymmetric Connection with Dark Matter 52