Why SUSY? Key Words LECTURE OUTLINE. Between Supersymmetry and Dark Matter Teruki Kamon KNU/TAMU. Probing the Connection.

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1 Why SUSY? Beyond the SM: Probing the Connection Between Supersymmetry and Dark Matter Teruki Kamon KNU/TAMU This is what I said at Lecture 00. Course Description Since March 00, the Large Hadron Collider (LHC) is delivering proton-proton collisions with a center-ofmass energy of 7 TeV. Both CMS and ATLAS collaborations are reporting results at low p T physics and re-discoveries of various Standard Model (SM) particles (e.g., J/psi and Upsilon particles in 70s, W and Z bosons in 80s, top quark in 90 s). The rediscoveries help understanding the detector performance and preparing discovering new physics at a TeV scale, which is one of the high priority programs at the LHC. Especially, supersymmetry (SUSY) allows for the construction of models of particle physics building up to the grand unification (GUT) scale and linking to early universe. This course is designed as an introductory course for graduate students to cover a broad spectrum of particle physics at the LHC, including basic concepts of the collider complex and experimental apparatus as well as how to probe physics beyond the SM. PHYS 809 (00) Key Words LECTURE OUTLINE ) LHC The world s largest accelerator ) TeV Trillion (0 ) electron-volt (ev =.6 X 0 9 J) 3) SM The current theory of particle physics 4) SUSY A new theory of particle physics with a dark matter candidate 5) GUT Unification of three fundamental interactions 6) Early Universe ~0-7 sec after Big Bang Brief Review: Standard Model (SM) Reasons for going beyond the SM Supersymmetric (SUSY) SM Existing experimental constraints Prospects of discovering SUSY in the future dark matter experiments Prospects of discovering SUSY in the Large Hadron Collider (LHC) and future Linear Collider (LC) Summary Why SUSY? 3 4

2 Standard Model (SM) Glashow 6, Weinberg 67, Salam 68 Underlying theory: a gauge theory (e.g., QED) Quantum Mechanics + Special Relativity Standard Model SU(3) SU() U() s Predictions were tested in experiments. 973 B.S. Neutral CERN SPS (400 GeV p) 983 M.S. W/Z CERN SppS _ (540 GeV pp ) 995 Ph.D. Top Fermilab Tevatron (.8 TeV pp ) Remarkable accuracy: 6 quarks, 6 leptons and gauge particles 5 M M exp Z theory Z Explains most of the data! GeV GeV 6 [Q] Too Heavy t and Non-Zero QUARK MASSES M top ev [Q] Higgs Boson (h) Yet to be discovered a. It provides masses to the quarks and leptons. M up 6 ~ 5 0 ev h Yet to be discovered b. The SM prediction: GeV W. Marciano 04 c. Experimental bound: M h > 4 GeV NEUTRINO MASSES M ev Neutrino masses are non zero! The SM can not accommodate nonzero neutrino mass!!! See recent results from SuperKamiokande, SNO, KamLAND, KK, MACRO, MiniBoon, TK, MINOS/NOVA, DayaBay, d. One of four experimental group at the LEP (e + e collider) at CERN claimed to have observed the signal of Higgs boson with M h = 5 GeV. The other groups however could not confirm it. The Tevatron at Fermilab might discover it in -4 years. LHC at CERN will discover Higgs boson. 7 8

3 Three Fundamental Interactions Photon: carriers of the electromagnetic force Gluons: carriers of the strong force Q low e.g., Running Couplings ( e e e e ) = /34 = /7 W, Z bosons: carriers of the weak force Q high (Q = M pl ) =? 9 0 Beyond the SM The SM works very well at ~00 GeV. (Strength of Force) Three gauge couplings do not meet at a single point. But we want to build a theory which goes to a higher scale. Grand Unified Theory

4 Standard Model : Dream of Unification Structural Defect in the SM Problem a. The Higgs mass becomes too large at scale of a few TeV (000 x M proton ). b. There should be some new theory at this energy scale and this theory would keep the Higgs mass under control. The contribution to the Higgs mass Boson loop B Fermion loop F 3 = Scale of new physics 4 Structural Defect in the SM Possible Solutions (= New Physics) a. Technicolor: Higgs is not a fundamental particle. Experimental data do not allow this theory any more. Supersymmetric SM The fundamental law(s) of nature is hypothesized to be symmetric between bosons and fermions. Fermion (S = ½ ) Boson (S = 0 or ) b. Extra dimension (ED) at (~)TeV scale. EDs appear at around TeV scale. c. Supersymetric SM Have they been observed? Not yet. 5 6

5 [Ref] SUSY Transformation Feynman Diagrams for SUSY Supersymmetric partner of W boson Supersymmetric partner of Z boson Lightest neutralinos are always in the final state! This neutralino is the dark matter candidate!! 7 What do we gain if the theory is supersymmetric? 8 Supersymmetric Unification Grand Unified Picture! and Dark Matter M SUSY ~TeV Higgs mass does not become large at any scale. The top quark mass is predicted to be 50 to 00 GeV. D0 and CDF measured: M top = 73 GeV 9 0

6 Supersymmetry: Elegant Solution Many new particles (00 GeV a few TeV). This means the SUSY models have more than 00 parameters in a general framework. Minimal Supergravity Model SUSY model with two Higgs fields in the framework of unification: ) All SUSY masses are unified at the grand unified scale. m m / 0 for gaugino masses for squarks and sleptons Whatever happened to elegant solutions? Let s consider a minimal framework. ) Two more parameters: A 0 tan <H >, <H > <H>, tan [Ref] Image of Unification t = 4 billion years t 500 M yrs Galaxy Formation Relic Radiation Decouples: WMAP s 0 7 s SUSY Relic 0 s s Quantum Gravity 4

7 t = 4 billion years t 500 M yrs Galaxy Formation Relic Radiation Decouples: WMAP s t = 4 billion years t 500 M yrs Galaxy Formation Relic Radiation Decouples: WMAP s 0 7 s SUSY Relic 0 s 0 7 s SUSY Relic 0 s 0 43 s Quantum Gravity s Quantum Gravity 6 Probing the Crucial Connection DM = Neutralino ( ~ 0 ) The amount of the DM can be calculated as a function of SUSY parameters. Connecting Particle Physics and Cosmology Thermal equilibrium x f dx ~ 0 h ~ 0 ann Freeze out v dn 3Hn v n dt n eq Current Is it possible to observe these features in particle-physis experiments? Dark matter detection? Collider experiments? c.f.) x T 7 8

8 Connecting Particle Physics and Cosmology Cosmology at the LHC! 9 30 E Road Map to Unified Theory Hunt for Dark Matter String Theory SUSY GUT x at_colliders/ Phys. Lett. B 505 (00) 6 Phys. Lett. B 538 (00) Phys. Lett. B 6 (005) 3 Phys. Lett. B 68 (005) 8 Eur. Phys. J. C46 (006) 43 Phys. Lett. B 639 (006) 46 Phys. Lett. B 649 (007) 73 Phys. Rev. Lett. 00 (008) 380 Phys. Rev. D 79 (009) hep-ph/ , submitted to Phys. Rev. D. 3 3

9 Hunt for Particles Real way to see Top (or Heavy Particles) Quarks. Neutrons. Mesons. All those particles You can t see. That s what drove me to drink. But now I can see them! Existing Bounds from Experiments [] Higgs Mass (M h ): 4 GeV < M h < 30 GeV (The Higgs mass depends on the mass parameters m 0 and m /,anda 0 and tan.) [] Branching Ratio b s : CLEO: ( ) x 0 4 SM : ( ) x 0 4 Br m Excluding parameter space based on the SUSY particle masses. SUSY Excluded Region in SUSY World Mass of Squarks and Sleptons Excluded Mass of Gauginos 35 36

10 Existing Bounds from Experiments [3] Magnetic Moment of Muon: Excluded Region in SUSY World Mass of Squarks and Sleptons Excluded Mass of Gauginos Existing Bounds from Experiments [4] Dark Matter: Allowed region The relic density is expressed as where CDM = Neutralino ( ) constitutes the dark matter in this model. It is the lightest and stable particle in our model. In order to calculate CDM,weneedtoknow the density of the remaining neutralinos when they stopped annihilating each other, neutralino annihilation, i.e. m SUSY can be expressed in terms of our msugra parameters. CDM CDM ~ 0 39 Co-annihilation [Griest and Seckel 9]: An accidental near degeneracy occurs naturally for light stau ~ in msugra. ~ 0 M 0 e ~ Here M M ~ 0 M ~. This diagram also contributes to the relic density along with the other neutralino annihilation diagrams. This is a generic feature of any SUSY model. Other regions (focus point, annihilation funnel): mostly beyond the LHC But, can be observed at a possible energy upgrade of the LHC. 40

11 Excluded Region in SUSY World Mass of Squarks and Sleptons Excluded Allowed region Mass of Gauginos 4 Small tan Region narrow co-annihilation corridor Large tan Region narrow co-annihilation corridor Mass of Squarks and Sleptons Mass of Gauginos 43 R. Arnowitt, B.D., T. Kamon, M. Tanaka, Phys. Lett. B538, (00) R. Arnowitt, B.D., B. Hu, hep-ph/03003 (talk at BEYOND '03) A. Lahanas, D.V. Nanopoulos, Phys. Lett. B568, 55 (003) J. Ellis et al., Phys. Lett. B565,76 (003) H. Baer et al., JHEP 007, 050 (00) 44

12 Large tan Region narrow co-annihilation corridor Key SUSY Signals Large tan 3 rd generation SUSY particles become special. 45 The LHC is powerful enough to produce many SUSY particles. Can we detect the co-annihilation signal (small M)? ~ 0 ~ 46 Collider Experiments Questions: a.what are the signals from the narrow co-annihilation corridor? ~ 0 ~ b.what is the accuracy of the measurement on M? M ~ M 5 5 GeV M ~ 0 ~ Collider Experiments:.Tevatron ( TeV pp ).LHC (4 TeV pp ) 3.LC (500 or 800 GeV e + e ) Collider Experiments (cont d) Question: What are the signals from the narrow co-annihilation corridor? Tevatron The reach of the Tevatron is not high enough. V. Krutelyov, R. Arnowitt, B.D., T. Kamon, P. McIntyre, Y. Santoso, Phys. Lett. B505, 6 (00); R. Arnowitt, B.D., T. Kamon, M. Tanaka, Phys. Lett. B538, (00) We will first discuss the LC since it measures the mass very accurately. 47 Small M ~ 0 ~ LHC

13 Measurement of M at the LHC Squark-gluino production cross section is very large. SUSY Signals at the Tevatron Direct searches Key decay: ~ 0 ~ ~ Signal: > +jets(q s, g s) + missing energy ( ~ 0 ) Backgrounds: SM tt and other SUSY processes 0 49 The reach is 00 GeV for m / V. Krutelyov, R. Arnowitt, B.D., T. Kamon, P. McIntyre, Y. Santoso, Phys. Lett. B505, 6 (00) Promising search: B s + SM branching ration: 0 9 SUSY: 0 7 ~0 8 R. Arnowitt, B.D., T. Kamon, M. Tanaka, Phys. Lett. B538, (00) V. Krutelyov, Ph.D. thesis, May 005 (expected) 50 Dark Matter Experiments The neutralinos can be detected in the dark matter detectors by scattering: ~ ~ 0 0 Selected DM Experiments DAMA (00-kg sodium Iodide crystal) DAMA/LIBRA (50-kg sodium Iodide crystal ), at Gran Sasso, Italy CDMS (Cryogenic Dark Matter Search) SuperCDMS XENON0 (5-kg liquid xenon) XENON00 KIMS (Korea Invisible Mass Search), Jeombong Mountain, Korea XMASS (800-kg spherical Japan liquid xenon) in Kamioka, nucleus recoil This recoil can be detected in various ways such as ionization and scintillation. The existence of SUSY in the nature can be proved in these experiments. Cross Section WIMP Experiments Collder Experiments Predicted by model R. Arnowitt, B.D. Y. Santoso, B.Hu, Phys. Lett. B505, 77 (00) J. Ellis, D. Nanopoulos, K. Olive, Phys. Lett. B508, 65, (00) H. Baer et al., JCAP 0309, 007 (003) Mass 5 5

14 Neutralino-Proton Cross Section 0 pb 53 - order of magnitude below the current experimental sensitivity 54 Other Experiments Measuring the properties of B mesons at BaBar (SLAC) and Belle (Japan) The SM deficits in the recent results Hints of new physics The SUSY models are explaining the deficits. B.D., C. Kim, S. Oh, Phys. Rev. Lett. 90, 080 (003) R. Arnowitt, B.D., B. Hu, Phys. Rev. D68, (003) SUSY GUT models are tested at the neutrino experiments. B.D., Y. Mimura, R. Mohapatra, Phys. Rev. D69, 504 (004), Phys. Lett. B 603, 35 (004); hep-ph/0405 R. Arnowitt, B.D., B. Hu, Nucl. Phys. B68, 347 (004) 55 Conclusion SUSY cures the problems of the SM. It fulfills the dream of Grand Unification and explains the dark matter (DM) content. The minimal supergravity (msugra) model, based on the unification framework, is already constrained by many experiments. The DM content of the universe requires some specific features of the msugra parameter space e.g. coannihilation. The signal of the co-annihilation at the colliders will confirm the model. We think that the LHC will also be able to probe this signal. A linear collider will be able to probe this signal and accurately measure the mass. 56