Matter and AntimatterDezso Horváth
KFKI Research Institute for Particle and Nuclear Physics, Budapestand Institute for Nuclear Research, Debrecen
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 1
Outline
Symmetries in the Standard Model
Antiparticles and CPT Invariance
Antimatter in the Universe?
Testing CPT Symmetry
Supersymmetry?
Search for Supersymmetry at LHC
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 2
Symmetries
Deeper microstructure ⇒ greater role of symmetries
Field theory: Noether’s theoremContinuous symmetry ⇒ conserving quantity
Spatial displacement ⇒ momentumTime displacement ⇒ energyRotation ⇒ angular momentumGauge invariance ⇒ charge (electric, color, fermion)
Popular journal of Fermilab and SLAC:symmetry — dimensions of particle physics
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 3
The Zoo of the Standard Model
colored quarks ⇒ colorless composite hadronshadrons = mesons (qq) + baryons (qqq)
Nucleons (I = 12): p = (uud) n = (udd) p = (uud)
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 4
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
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 5
Glory Road of Standard Model
Summer 2009 status
Includes hundreds ofmeasurements of all experiments
|Expt – theory|expt. uncertainty
Slightly deviating quantitychanges from year to year
Now it is forward-backwardasymmetry of
e+e− → Z → bb
LEP Electroweak Working Group:
http://lepewwg.web.cern.ch/
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 6
Spontaneous symmetry breaking⇒ mass
Freefermion
Higgsboson
David J. Miller and CERN: http://www.hep.ucl.ac.uk/∼djm/higgsa.html
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 7
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) > 114.4 GeV
“It was in 1972 ...
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) 86-88.
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 8
Fitting the mass of the Higgs boson
0
1
2
3
4
5
6
10030 300
mH [GeV]
∆χ2
Excluded Preliminary
∆αhad =∆α(5)
0.02758±0.00035
0.02749±0.00012
incl. low Q2 data
Theory uncertaintyMarch 2009 mLimit = 163 GeV
Summer 2009 status
Sensitivityof SM parameters
to Higgs mass
114< MH < 163GeV(95 % confidence)
LEP Electroweak Working Group:http://lepewwg.web.cern.ch/LEPEWWG/
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 9
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
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 10
Antimatter in the Universe?
Is it possible to explain its lack without assuming CPTviolation?
YES: Theory of Andrei Sakharov, 1967Baryogenesis (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
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 11
Accelerators at CERNUntil 2000 From 2008
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 12
LHC: the Largest Microscope
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 13
LHC: the dipole magnets
1232 superconducting dipoles (before installation)(L = 15 m, M = 35 t, T = 1.9 K, B = 8.3 T)
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 14
LHC: magnets in tunnel
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 15
The LHCb experiment at CERN
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 16
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 (∼ 1019 GeV).Above Planck scale new physics ⇒Lorentz violation possible
Quantum gravity: fluctuations ⇒ Lorentz violationloss of information in black holes ⇒ unitarity violation
Motivation for testing CPT at low energy
Quantitative expression of Lorentz and CPT invarianceneeds violating theory
low-energy tests can limit possible high energyviolation
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 17
How to testCPT?
Particle = – antiparticle ?
|m(K0)−m(K0)|/m(average) < 10−18
proton ∼ antiproton? (compare m, q,~µ)
hydrogen ∼ antihydrogen (antiproton+positron)?(2S−1S transition!)
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 18
Antihydrogen (antiproton+positron)
2-photon 2S−1S transition:
Slow transition ⇒ narrow lineTwo counter-propagating photons ⇒ Doppler-free
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 19
Accelerators at CERNUntil 2000 From 2008
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 20
The Antiproton Decelerator at CERNis built to test CPT invariance
Three experiments test CPT:
ATRAP: q(p)/m(p) ↔ q(p)/m(p)
H(2S−1S) ↔ H(2S−1S)
ATHENA ⇒ ALPHA:
H(2S−1S) ↔ H(2S−1S)
ASACUSA: q(p)2m(p) ↔ q(p)2m(p)
µℓ(p) ↔ µℓ(p)
H ↔ H HF structure
RED: done, GREEN: plannedc©Ryugo S. Hayano
Lots of H produced, spectroscopy
is aheadHayano, Hori, Horváth and Widmann: Repts. Prog. Phys.70 (2007) 1995-2065.
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 21
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 violationSU(3) gauge invariance
conserves color chargegives rise to strong interactionsno violation
U(1)×SU(2) gauge invariancespontaneously broken by Higgs fieldgives rise to electroweak interactionproduces Higgs boson
What else?
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 22
Supersymmetry (SUSY): motivationTheoretical problems of Standard Model:
Naturalness (hierarchy): Mass of Higgs bosonquadratically diverges due to radiative corrections.Eliminated if fermions and bosons exist in pairs.
Dark matter and energy give dominant energy ofUniverse. 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 gaugecouplings converge at ∼ 1016 GeV but do not meet
All these would be solved by a universalfermion ⇔ boson supersymmetry.
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 23
Supersymmetry: partner particles
Charges (electric, color, fermion) identical
SUSY partners of fermionsLeptons (S= 1
2) scalar leptons (S= 0)
e, µ, τ e, µ, τνe, νµ, ντ νe, νµ, ντ
Quarks (S= 12) scalar quarks (S= 0)
u, d, c, s, t, b u, d, c, s, t, b
Antiparticle ↔ antipartner
XL, XR ↔ X1, X2
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 24
SUSY partners of bosons
Elementary boson spin SUSY partner spinphoton: γ 1 photino: γ 1
2
weak bosons: 1 zino: Z 12
Z, W+, W− 1 wino: W+, W− 12
gluons: g1, ... g8 1 8 gluinos: g1, ... g812
Higgs fields 0 higgsinos 12
H01, H0
2, H+1 , H−
2 H01, H0
2, H+1 , H−
2
graviton 2 gravitino 32
Two Higgs doublets ⇒ 5 Higgs bosons: h, H, A, H+, H−
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 25
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 symmetrym
SUSY introduces a non-existing one
All this for a rational, cosistent theory
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 26
Unification of gauge interactions
Standard Model:
Gauge couplings get close athigh energies
SUSY:
Convergence at ∼ 1016 GeV.Extra particles ⇒ corrections
Frank Wilczek: Nature 433 (2005) 239
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 27
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∼ 100GeV
SUSY is already 50% discovered!!
We see half of all SUSY particles(except the Higgs-boson :-)...)
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 28
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), 1989 – 2000;
Large Hadron Collider (LHC), 2010 –
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 29
The Large Hadron Collider at CERN
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 30
Search for SUSY particles at LEPDifficult: hard to distinguish from SM reactions.
Scalar lepton formation e+e− → ℓ+ℓ−
Decay e.g. ℓ±→χ01ℓ
±, model-dependent cross sections
Look for e+e−→ ℓ+ℓ− + missing energy
Main background: e+e− → W+W−→ ℓ+νℓ−ν
LEP result (ALEPH + DELPHI + L3 + OPAL):
No supersymmetric particle below m∼ 90−100GeV(kinematic limit: LEP worked up to 200 GeV)
Statistical analysis ⇒ excluded parameter regions
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 31
Compact Muon Solenoid (CMS)
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 32
The CMS detector of LHC(Compact Muon Solenoid)
Weight: 12500 tons, 2∗ more iron, than in Eiffel tower
> 2000participants
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 10-15 p-p interactions
Event filter: ≈ 4000PC, 500 GBit/secEvent storage: ≈ 10 PB data, 10 PB MC per yearData handling: LHC Computing Grid (> 100sites)
Signal: lepton or jet orthogonal to beam,Larger mass easier to identify
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 33
Simulated H→ ZZ → eeqq at CMS
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 34
SUSY search with CMSSignal: Particles of SUSY pair → fermions + lighter SUSY
→ ... → fermions + LSP
Fermion cascade with missing transverse momentum
g → bb → χ02 b b→ ℓ+ ℓ− b b→ χ0
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
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 35
Angels and Demons at CERNNovel by Dan Brown, film with Tom Hanks
Terrorists steal 1 g of antimatter from a secret CERN lab to destroy theVatican, Hanks stops them (of course)
CERN offered location, but film was taken in Los AngelesCERN: home page, special exhibition, talks
True: LHC underground, antimatter produced (few atoms)False: No secret lab, 1 g antimatter in 109 years
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 36
LHC: the Good, the Bad and the Ugly
GoodEnormous discovery potential:Various reactions at very high
energies,huge luminosity.
BadTerrible background,
interesting events happenat probability 10−6−10−3
UglyAny interesting event is
accompanied by 10–20 p-pcollisions giving high combinatorial
backgrounds.
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 37
SUMMARY
No Higgs boson, nor supersymmetry found at LEPLHC starts in 2009 with low luminosity, at 10 TeV
We hope for discoveries from 2010Even 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 constructionILC plans are developing worldwide
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 38
Thanks for your attention
Dezso Horváth: Matter and Antimatter Symmetry Festival 2009 Budapest, 31 July — 05 August 2009 – p. 39