Matter and Antimatter

Transcription

1 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 1 Matter and Antimatter Dezső Horváth horvath@rmki.kfki.hu KFKI Research Institute for Particle and Nuclear Physics, Budapest and Institute for Nuclear Research, Debrecen

2 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 2 Outline Symmetries in the Standard Model Antiparticles and CPT Invariance Antimatter in the Universe? Testing CPT Symmetry Supersymmetry? Search for Supersymmetry at LHC

3 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 3 Symmetries Deeper microstructure greater role of symmetries Field theory: Noether s theorem Continuous symmetry conserving quantity Spatial displacement momentum Time displacement energy Rotation angular momentum Gauge invariance charge (electric, color, fermion) Popular journal of Fermilab and SLAC: symmetry dimensions of particle physics

4 The Zoo of the Standard Model colored quarks colorless composite hadrons hadrons = mesons (qq) + baryons (qqq) Nucleons (I = 1 2 ): p = (uud) n = (udd) p = (uud) Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 4

5 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 5 Interactions Standard Model: Free Dirac (point-like) fermion + local U(1) SU(2) symmetry electroweak interaction (γ, Z, W ± ) + local SU(3) symmetry strong interaction (8 gluons) + Higgs field with spontaneous symmetry breaking masses, convergence (+ Higgs boson) Fundamental job of particle physics: study symmetries Father of (quantum) field theory: Steven Weinberg

6 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 6 Glory Road of Standard Model Summer 2009 status Includes hundreds of measurements of all experiments Expt theory expt. uncertainty Slightly deviating quantity changes from year to year Now it is forward-backward asymmetry of e + e Z b b LEP Electroweak Working Group:

7 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 7 Spontaneous symmetry breaking mass Free fermion Higgs boson David J. Miller and CERN: djm/higgsa.html

8 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 8 Where is the Higgs-boson? By-product of spontaneous symmetry breaking of the SM Most wanted particle of physics as the only missing piece of the Standard Model. Experimentally not (yet?) observed, LEP: M(H) > GeV It was in that my life as a boson really began Peter Higgs: My Life as a Boson: The Story of The Higgs, Int. J. Mod. Phys. A 17 Suppl. (2002)

9 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 9 Fitting the mass of the Higgs boson χ March 2009 Theory uncertainty α had = α (5) ± ± incl. low Q 2 data m Limit = 163 GeV Summer 2009 status Sensitivity of SM parameters to Higgs mass 1 Excluded Preliminary m H [GeV] 114 < M H < 163 GeV (95 % confidence) LEP Electroweak Working Group:

10 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 10 CPT Invariance Basic assumption of field theory: CPT p(r,t)> p( r, t)> p(r,t)> meaning free antiparticle particle going backwards in space and time. Giving up CPT one has to give up: locality of interactions causality, or unitarity conservation of matter, information,... or Lorentz invariance Motivation to doubt: Asymmetric Universe: no antimatter galaxies

11 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 11 Antimatter in the Universe? Is it possible to explain its lack without assuming CPT violation? YES: Theory of Andrei Sakharov, 1967 Baryogenesis (the prevalence of baryons against antibaryons) in the Universe can be explained if the three (Sakharov) conditions are fulfilled: violation of baryon number conservation violation of CP-symmetry faster expansion than baryon-antibaryon production low chance for subsequent annihilation. CP-violation observed, baryon number violation not. Experimental test: LHCb at CERN

12 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 12 Accelerators at CERN Until 2000 From 2008

13 LHC: the Largest Microscope Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 13

14 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 14 LHC: the dipole magnets 1232 superconducting dipoles (before installation) (L = 15 m, M = 35 t, T = 1.9 K, B = 8.3 T)

15 LHC: magnets in tunnel Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 15

16 The LHCb experiment at CERN Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 16

17 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 17 CPT Invariance: violation? Theoreticians in general: CPT is NOT violated CPT -violating theories: (Alan Kostelecký, F.R. Klinkhamer, N.E. Mavromatos et al) Standard Model valid up to Planck scale ( GeV). Above Planck scale new physics Lorentz violation possible Quantum gravity: fluctuations Lorentz violation loss of information in black holes unitarity violation Motivation for testing CPT at low energy Quantitative expression of Lorentz and CPT invariance needs violating theory low-energy tests can limit possible high energy violation

18 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 18 How to test CPT? Particle = antiparticle? m(k 0 ) m(k 0 ) /m(average) < proton antiproton? (compare m, q, µ) hydrogen antihydrogen (antiproton+positron)? (2S 1S transition!)

19 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 19 Antihydrogen (antiproton+positron) 2-photon 2S 1S transition: Slow transition narrow line Two counter-propagating photons Doppler-free

20 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 20 Accelerators at CERN Until 2000 From 2008

21 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 21 The Antiproton Decelerator at CERN is built to test CPT invariance hree experiments test CPT: TRAP: q(p)/m(p) q(p)/m(p) H(2S 1S) H(2S 1S) THENA ALPHA: H(2S 1S) H(2S 1S) SACUSA: q(p) 2 m(p) q(p) 2 m(p) µ l (p) µ l (p) H H HF structure ED: done, GREEN: planned c Ryugo S. Hayano Lots of H produced, spectroscopy is ahead Hayano, Hori, Horváth and Widmann: Repts. Prog. Phys. 70 (2007)

22 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 22 Lost symmetries?.. the fundamental equations of physics have more symmetry than the actual physical world does Frank Wilczek: In search of symmetry lost, Nature 433 (2005) 239 Accidental symmetries Steven Weinberg CPT invariance: fundamental, absolute, no violation SU(3) gauge invariance conserves color charge gives rise to strong interactions no violation U(1) SU(2) gauge invariance spontaneously broken by Higgs field gives rise to electroweak interaction produces Higgs boson What else?

23 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 23 Supersymmetry (SUSY): motivation Theoretical problems of Standard Model: Naturalness (hierarchy): Mass of Higgs boson quadratically diverges due to radiative corrections. Eliminated if fermions and bosons exist in pairs. Dark matter and energy give dominant energy of Universe. What is DM that we observe its gravity only? Gravity: does not fit in system of gauge interactions (strong, electromagnetic, weak) Convergence of interactions: in SM the three gauge couplings converge at GeV but do not meet All these would be solved by a universal fermion boson supersymmetry.

24 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 24 Supersymmetry: partner particles Charges (electric, color, fermion) identical SUSY partners of fermions Leptons (S = 1 2 ) scalar leptons (S = 0) e, µ, τ ẽ, µ, τ ν e, ν µ, ν τ ν e, ν µ, ν τ Quarks (S = 1 2 ) scalar quarks (S = 0) u, d, c, s, t, b ũ, d, c, s, t, b Antiparticle antipartner X L, X R X 1, X 2

25 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 25 SUSY partners of bosons Elementary boson spin SUSY partner spin 1 photon: γ 1 photino: γ 2 1 weak bosons: 1 zino: Z 2 Z, W +, W 1 wino: W +, W gluons: g 1,... g gluinos: g 1,... g Higgs fields 0 higgsinos 2 H 0 1, H0 2, H+ 1, H 2 H 0 1, H 0 2, H + 1, H 2 3 graviton 2 gravitino 2 Two Higgs doublets 5 Higgs bosons: h, H, A, H +, H

26 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 26 Supersymmetry? Supersymmetry is obviously broken: no such particles, or maybe with much larger masses What is a broken symmetry good for? Higgs mechanism: symmetry violating field masses, renormalisation Higgs field violates an existing symmetry SUSY introduces a non-existing one All this for a rational, cosistent theory

27 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 27 Unification of gauge interactions Standard Model: Gauge couplings get close at high energies SUSY: Convergence at GeV. Extra particles corrections Frank Wilczek: Nature 433 (2005) 239

28 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 28 Supersymmetry: + and naturalness of theory + cold dark matter of the Universe (23 %) = LSP unification of interactions includes gravitation BUT: Mechanism of SUSY breaking?? Many different models Many new parameters Not seen below m 100 GeV SUSY is already 50% discovered!! We see half of all SUSY particles (except the Higgs-boson :-)...)

29 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 29 Search for SUSY particles Creation in pairs, decay to ordinary and SUSY particles Properties depend on models and parameters Lightest SUSY particle (LSP) unobservable missing energy observed Which one is LSP? Model dependent. SUSY (and Higgs) search at CERN: Large Electron-Positron collider (LEP), ; Large Hadron Collider (LHC), 2010

30 The Large Hadron Collider at CERN Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 30

31 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 31 Search for SUSY particles at LEP Difficult: hard to distinguish from SM reactions. Scalar lepton formation e + e l + l Decay e.g. l ± χ 0 1 l±, model-dependent cross sections Look for Main background: e + e l + l + missing energy e + e W + W l + νl ν LEP result (ALEPH + DELPHI + L3 + OPAL): No supersymmetric particle below m GeV (kinematic limit: LEP worked up to 200 GeV) Statistical analysis excluded parameter regions

32 Compact Muon Solenoid (CMS) Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 32

33 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 33 The CMS detector of LHC (Compact Muon Solenoid) Weight: tons, 2 more iron, than in Eiffel tower > 2000 participants Largest (superconducting) solenoid on Earth: 13 m long, 5.8 m inner diameter, B = 4 Tesla Proton bunches collide at 40 MHz (25 ns!) (uud + uud) many hadrons Each event contains p-p interactions Event filter: 4000 PC, 500 GBit/sec Event storage: 10 PB data, 10 PB MC per year Data handling: LHC Computing Grid (> 100 sites) Signal: lepton or jet orthogonal to beam, Larger mass easier to identify

34 Simulated H ZZ eeqq at CMS Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 34

35 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 35 SUSY search with CMS Signal: Particles of SUSY pair fermions + lighter SUSY... fermions + LSP Fermion cascade with missing transverse momentum g b b χ 0 2 b b l + l b b χ 0 1 l+ l b b Measurements for all parameter values of all models?? Collaboration with theorists: check benchmark points in parameter space Given model and parameters quantitative prediction of SUSY properties and reaction probabilities can be tested experimentally

36 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 36 Angels and Demons at CERN Novel by Dan Brown, film with Tom Hanks Terrorists steal 1 g of antimatter from a secret CERN lab to destroy the Vatican, Hanks stops them (of course) CERN offered location, but film was taken in Los Angeles CERN: home page, special exhibition, talks True: LHC underground, antimatter produced (few atoms) False: No secret lab, 1 g antimatter in 10 9 years

37 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 37 LHC: the Good, the Bad and the Ugly Good Enormous discovery potential: Various reactions at very high energies, huge luminosity. Bad Terrible background, interesting events happen at probability Ugly Any interesting event is accompanied by p-p collisions giving high combinatorial backgrounds.

38 Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 38 SUMMARY No Higgs boson, nor supersymmetry found at LEP LHC starts in 2009 with low luminosity, at 10 TeV We hope for discoveries from 2010 Even 10 TeV collision energy is enough for discoveries: Higgs boson(s), SUSY particles For precise studies one needs e + e collider: International Linear Collider (ILC) LHC design started before LEP construction ILC plans are developing worldwide

39 Thanks for your attention Dezső Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July 05 August 2009 p. 39