Testing CPT Invariance with Antiprotonic Helium

Testing CPT Invariance with Antiprotonic Helium Dezső Horváth horvath@rmki.kfki.hu. KFKI Research Institute for Particle and Nuclear Physics, Budapest and Institute of Nuclear Research, Debrecen, Hungary Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.1/26

Outline CPT invariance and its tests The Antiproton Decelerator at CERN p-he Spectroscopy The Charge and Mass of the Antiproton The Magnetic Moment of the Antiproton Outlook Brief overview based on our review paper: R. S. Hayano, M. Hori, D. Horváth, E. Widmann: Antiprotonic Helium and CPT Invariance Reports on Progress in Physics 70 1995-2065 (2007). New results: Naoya Ono and Thomas Pask Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.2/26

Symmetries Deeper microstructure greater role of symmetries More basic role in particle physics than in chemistry or solid state physics (origin!) Field theory: Noether s theorem Global 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 Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.3/26

CPT Invariance Charge conjugation: Space reflection: Time reversal: Cp(r,t) p(r,t) Pp(r,t) p( r,t) T p(r,t) p(r, t) Basic assumption of field theory: CPT p(r,t) p( r, t) p(r,t) meaning 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 Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.4/26

CPT Invariance: violation? Most theoreticians: CPT cannot be violated CPT -violating theories: (Alan Kostelecký, F.R. Klinkhamer, N.E. Mavromatos et al) Standard Model valid up to Planck scale ( 10 19 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 Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.5/26

How to test CPT? Particle = antiparticle? m(k 0 ) m(k 0 )/m(average) < 10 18 proton antiproton? (compare m, q, µ) hydrogen antihydrogen? (2S 1S) ν ν mass, mixing LSND result interpreted via CPT-violation, but discredited by MiniBooNE in 2007 Lorentz violation: orientation dependence of measurement BaBar s sidereal study of B 0 B 0 oscillation No effect with 2.8σ significance: arxiv:0711.2713v1 (27 Nov 2007) Strongest argument pro CPT: Feynman diagrams Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.6/26

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 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 the Higgs boson Spontaneously broken supersymmetry? CPT invariance: fundamental, absolute, no violation?? Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.7/26

The Antiproton Decelerator at CERN is built to test CPT invariance Three experiments test CPT: ATRAP: q(p)/m(p) q(p)/m(p) H(2S 1S) H(2S 1S) ALPHA: H(2S 1S) H(2S 1S) ASACUSA: q(p) 2 m(p) q(p) 2 m(p) µ l (p) µ l (p) H H HF structure RED: done, GREEN: planned c Ryugo S. Hayano Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.8/26

Accelerators at CERN Until 1996 From 2008 Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.9/26

The Antiproton Decelerator: cooling Momentum p[gev/c] 3.57 2.0 pbar injection Bunch rotation Stochastic cooling 17 s. Stochastic cooling 6.6 s. Electron cooling 16s. Electron cooling 8 s. Rebunching Fast Extraction 0.3 0.1 RF ON: 12 35 54 71 85 time [s] 4 10 7 100 MeV/c antiprotons every 85 s Pavel Belochitskii: AIP Conf. Proc. 821 (2006) 48 Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.10/26

Mass and Charge of Antiproton Proton s well (?) known: m(p)/m(e) = 1836.15267261(85) q(e) = 1.602176462(63) C Precision: 5 10 10 and 4 10 8 Relative measurements: proton vs. antiproton Cyclotron frequency in trap q/m TRAP ATRAP collaboration Harvard, Bonn, München, Seoul p and H together 10 10 precision Atomic transitions: E n m red c 2 (Zα) 2 /(2n) m q 2 PS-205 ASACUSA collaboration Tokyo, Budapest, Debrecen, Vienna + Brescia + Munich Atomic Spectroscopy And Collisions Using Slow Antiprotons Asakusa, Tokyo Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.11/26

Metastable hadronic atoms In matter (gas, liquid, solid) τ(hadron) 1 ps except X He: K, π : τ 0 ; p: 3 4 µs Trapping p in a long-lived 3-body system (atomcule) Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.12/26

Principle of laser spectroscopy τ µ Wavelengths in nm Induce transition between long-lived and short-lived state Force prompt annihilation Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.13/26

ASACUSA: Spectroscopy Setup Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.14/26

aser spectroscopy of antiprotonic helium N. Morita et al, Phys. Rev. Lett. 72 (1994) 1180 1183. Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.15/26

Transition frequencies in isolated phe + atoms Exp. precision limited by: collisions, Doppler broadening, laser linewidth 1996-2002: measure density dependence, extrapolate to zero 2003-2004: reduce collisional effects by stopping slow p from RFQ post-decelerator in low-pressure (< 1 mbar), cryogenic target 2005-2006: reduce laser linewidth, increase stability 2007: start 2-photon spectroscopy M. Hori et al., Phys. Rev. Lett. 87 (2001) 093401. Last published CPT-violation limit: 2 ppb (2 10 9 ) M. Hori et al., Phys. Rev. Lett. 96 (2006) 243401. Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.16/26

Radiofrequency quadrupole decelerator y z 0 x 5 cm Focussing-defocussing in alternate planes U 170 kv; f 202 MHz; bias ±55 kv 5,3 MeV 65 kev: efficiency 30% RF buncher energy corrector Solenoid magnets Cherenkov detectors p RFQD Dipole magnets Laser Quadrupole triplet Quadrupole magnets Cryogenic helium target Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.17/26

Resolution development 2000 2002 2004 Resonance profile of the (n,l) = (37,35) (38,34) transition at λ = 726.1 nm Resolution and stability Newest results and details: Naoya Ono s talk Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.18/26

Determination of m(p),q(p) 8 Antiprotonic Helium 6 4 TRAP 6 4 2 2-6 -4-2 2 4 6 8-6 -4-2 2 4 6-2 -2-4 -6-4 -6 Determination of antiproton mass and charge: possible deviation from those of the proton Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.19/26

Two-photon spectroscopy In low density gas main precision limitation: thermal Doppler broadening even at T < 6 K Excite l = 2 transition with 2 photons Two counterpropagating photons with ν 1 = ν 2 eliminate 1st order Doppler effect Far from resonance transition probability low needs too high laser power Near resonance transition rate ( E) 3 Laser linewidth should not overlap with resonance Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.20/26

1-photon vs 2-photon spectroscopy 417 nm 372 nm (36,34) 417 nm Virtual state E 372 nm (35,33) (34,32) Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.21/26

Near-resonant two-photon spectroscopy (n,l) = (36,34) (34,32) Doppler suppression: 417 nm 372 nm (36,34) ν γ1 γ 2 = ν 1 ν 2 ν 1 + ν 2 ν Doppler 417 nm Gain: 20 Limitation: residual Doppler, frequency chirp systematics Expected f few MhZ (solid-state lasers lower chirp) Virtual state (34,32) 372 nm E (35,33) Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.22/26

µ(p): level splitting in phe + atoms F =L 1/2 F =L 1/2 (n,l ) F =L 1/2 J + =L F =L 1/2 J + =L (n,l ) F =L 1/2 J + =L J =L 1 J =L 1 J =L 1 F + =L +1/2 (n,l) (n,l) ν HF + F + =L +1/2 (n,l) f + J ++ = L+1 ν HF J ++ = L+1 f + J ++ = L+1 F + =L+1/2 J + =L F + =L+1/2 J + =L F + =L+1/2 J + =L Step 1: depopulation of F + doublet with f + laser pulse Step 2: equalization of populations of F + and F - by microwave Magnetic moments µ(p) µ(p) CPT invariance OK E. Widmann, R.S. Hayano, T. Ishikawa, J. Sakaguchi, H. Yamaguchi, J. Eades, M. Hori, H.A. Torii, B. Juhász, D. Horváth, T. Yamazaki: Phys. Rev. Lett. 89 (2002) 243402. Details, new results: Thomas Pask R ++ /R ++ off Step 3: probing of population of F + doublet with 2nd f + laser pulse 1.15 1.10 1.05 1.00 0.95 + ν HF ν HF 12.86 12.88 12.90 12.92 12.94 12.96 ν MW (GHz) Microwave frequency scan Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.23/26

Conclusion Our last published result on the p mass using laser spectroscopy on 7 p 4 He + and 5 p 3 He + transitions is: m p /m e = 1836.152674(5) (M. Hori et al., Phys. Rev. Letters 96 (2006) 243401.) Present CPT -limit on p charge and mass 2 10 9 at 90% confidence level Assuming CPT validity our result can be combined with those for the proton: Precision of m p /m e 0.46% (CODATA 2002) 0.43% (CODATA 2006) Measuring the p magnetic moment (Thomas Pask) Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.24/26

Acknowledgement This work is supported by: Monbukagakusho (Grant No. 15002005), the Hungarian National Research Foundation (OTKA T046095, NK67974 and K72172) and EU FP6 Project MKTD-CT-2004-509252. Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.25/26

Laser system with frequency comb f f < 4 10 10 (M. Hori, A. Dax, R. S. Hayano, unpublished) Dezső Horváth: Testing CPT Invariance with Antiprotonic Helium PBAR08 Workshop Naha, Okinawa, 20-22 February 2008 p.26/26