Gabrielse Most Precise Tests of the Standard Model, Its Extensions and its Symmetries Gerald Gabrielse, Leverett Professor of Physics, Harvard University Spokesperson of the CERN ATRAP Collaboration Testing the Most Precise Prediction of the Standard Model  Electron magnetic moment Testing standard model extensions  Electron electric dipole moment Testing the Symmetries of the Standard Model  Q/M for the antiproton and proton  Antiproton and proton magnetic moments  Positron and electron magnetic moments (underway)  Antihydrogen and hydrogen structure (still in far future) Comparing Antimatter and Mater Gravity  Gravitational Redshift of the Antiproton and Proton Supported by US NSF and AFOSR Gabrielse Low Energy Particle Physics AMO Physics, Particle Physics, Plasma Physics methods and funding goals and facility can’t avoid

2 2Mp c LEAR and AD

1010

TRAP 4.2 K 0.3 meV

70 mK, lowest storage energy for any charged particles Gabrielse Gabrielse

Electron Magnetic Dipole Moment

• Most precise prediction of the standard model

• Most precisely measured property of an elementary particle

• Most precise confrontation of theory and experiment

• Greatest triumph of the standard model Gabrielse The Amazing Electron Electron orbits give atoms their size, but the electron itself may actually have no size 20000 electron masses 20 2 R2  10 m m* 10.3 TeV / c of binding energy for “ingredients”

Electron has angular momentum (spin) even though it has no size and nothing is rotating: 2 S m R   IA~  R2

Magnetic dipole moment: What about electric dipole?    S  S   d d  / 2  / 2 Gabrielse Standard Model of Prediction

2 3 4 5                e  1 CCCCC2   4    6    8    10    ...                 2m B a hadronic a weak  a new physics

Dirac 1 QED essentially exact

Hadronic

Weak aweak smaller Gabrielse The Standard Model Predicts the Electron Magnetic Moment

in terms of the 1e2 1 fine structure    4 c 137 constant 0  Gabrielse Probing 10th Order and Hadronic Terms

Dirac

QED Gabrielse

David Hanneke G.G. Shannon Fogwell Gabrielse Need Good Students and Stable Funding

Elise Novitski Joshua Dorr Shannon Fogwell Hogerheide David Hanneke Brian Odom, Brian D’Urso, 20 years Steve Peil, 8 theses Dafna Enzer, Kamal Abdullah Ching-hua Tseng Joseph Tan

N$F Gabrielse Cylindrical Penning Trap V~ 2 z2 x 2  y 2

• Electrostatic quadrupole potential  good near trap center • Control the radiation field  inhibit spontaneous emission by 200x (Invented for this purpose: G.G. and F. C. MacKintosh; Int. J. Mass Spec. Ion Proc. 57, 1 (1984) Gabrielse Trap with One Electron Quantum Cyclotron -charges------fc  150 GHz  2

n = 4 n = 3 n = 2 0.1 n = 1 m m hc  7.2 kelvin n = 0 y2

------Need low temperature B  6Tesla cyclotron motion T << 7.2 K 0.1 m m Gabrielse Quantum Measurement of the Electron Magnetic Moment  S    E ms s ( n  1/ 2)   c  / 2

  Spin flip energy:    BB  2  s s  eB   Cyclotron energy: c   2  B B c  B (the magnetometer) m

Bohr magneton e 2m

Need to resolve the quantum states of the cyclotron motion  Relativistic shift is 1 part in 109 per quantum level Gabrielse Quantum Jump Spectroscopy

• one electron in a Penning trap • lowest cyclotron and spin states

“In the dark” excitation  turn off all detection and cooling drives during excitation Gabrielse Inhibited Spontaneous Emission Application of Cavity QED

excite, measure time in excited state 30 t= 16 s 15 12 20 9 6

10 Y Axis 2 3 0 0 number of n=1 to n=0 decays -3 axial frequency shift (Hz) 0 10 20 30 40 50 60 0 100 200 300 decay time (s) time (s)

many other new methods Most precisely measured property of an elementary particle Gabrielse Electron Magnetic Moment Measured to 3 x 10-13

2.8 1013

(improved measurement is underway) Gabrielse

from measured fine structure constant Gabrielse From Freeman Dyson – One Inventor of QED Dear Jerry, ... I love your way of doing experiments, and I am happy to congratulate you for this latest triumph. Thank you for sending the two papers. Your statement, that QED is tested far more stringently than its inventors could ever have envisioned, is correct. As one of the inventors, I remember that we thought of QED in 1949 as a temporary and jerry-built structure, with mathematical inconsistencies and renormalized infinities swept under the rug. We did not expect it to last more than ten years before some more solidly built theory would replace it. We expected and hoped that some new experiments would reveal discrepancies that would point the way to a better theory. And now, 57 years have gone by and that ramshackle structure still stands. The theorists … have kept pace with your experiments, pushing their calculations to higher accuracy than we ever imagined. And you still did not find the discrepancy that we hoped for. To me it remains perpetually amazing that Nature dances to the tune that we scribbled so carelessly 57 years ago. And it is amazing that you can measure her dance to one part per trillion and find her still following our beat. With congratulations and good wishes for more such beautiful experiments, yours ever, Freeman. Gabrielse Test for Physics Beyond the Standard Model  g   1 aQED ()  aSM: Hadronic Weak  aNewPhysi c s B 2 Does the electron have internal structure?

m*  total mass of particles bound together to form electron

m 2 limited by the uncertainty in R5  1019 m m*  360 GeV / c  a independent a value m R2  1019 m m*  1 TeV / c2 if our uncertainty  a was the only limit

Not bad for an experiment done at 100 mK, but LEP does better R2  1020 m m* 10.3 TeV / c2 LEP contact interaction limit > 20000 electron masses of binding energy Gabrielse Gabrielse

Electron Electric Dipole Moment

• Most precise test of extensions to the standard model • 12 times more precise than previous measurements

   S  S Magnetic moment:    Electric dipole moment: d d  / 2  / 2

Well measured Does this also exist? Gabrielse Particle EDM Requires Both P and T Violation Magnetic moment: Electric dipole Moment:    S  S   d d  / 2  / 2

If reality is invariant under parity transformations P P  d = 0

T If reality is invariant under time reversal transformations T  d = 0 Gabrielse Standard Model of Particle Physics  Currently Predicts a Non-zero Electron EDM four-loop -38 Standard model: d ~ 10 e-cm level in perturbation Too small to measure by orders of magnitude theory best measurement: d ~ 2 x 10-27 e-cm

Weak interaction couples quark pairs (generations) CKM matrix relates to d, s, b quarks (Cabibbo-Kabayashi-Maskawa matrix)

almost the unit matrix Gabrielse Extensions to the Standard Model  Much Bigger, Measureable Electron EDM

An example

Low order contribution  larger moment

Low order contribution  vanishes

From Fortson, Sandars and Barr, Physics Today, 33 (June 2003) Gabrielse New Electron EDM Measurement is Almost Done Gabrielse Advanced Cold-Molecule Electron EDM

Harvard University Yale University John Doyle Group David DeMille Group Gerald Gabrielse Group

Jacob Baron, Wes Campbell, David DeMille, John Doyle, Gerald Gabrielse, Paul Hess, Nick Hutzler, Emil Kirilov, Brendon O’Leary, Cris Panda, Elizabeth Petrik, Ben Spaun, Amar Vutha, Adam West Funding from NSF Gabrielse How to Measure an Electron EDM

Put the EDM in an Electric Field

bigger is better   H  d E

Measure the energy shift for the system Gabrielse Cannot Use Electric Field Directly on an Electron or Proton

Simple E and B can be used for neutron EDM measurement (neutron has magnetic moment but no net charge)

Electric field would accelerate an electron out of the apparatus

Electron EDM are done within atoms and molecules (first molecular ion measurement is now being attempted) Gabrielse Schiff Theorem – for Electron in an Atom or Molecule Schiff (1963) – no atomic or molecular EDM (i.e. linear Stark effect) • from electron edm • nonrelativistic quantum mechanics limit

Sandars (1965) – can get atomic or molecular EDM (i.e. linear Stark effect) • from electron edm • relativistic quantum mechanics • get significant enhancement (D >> d) for large Z

Commins, Jackson, DeMille (2007) – intuitive explanation Schiff  Lorentz contraction of the electron EDM in lab frame

Schiff, Phys. Rev. Lett. 132, 2194 (1963); Sandars, Phys. Rev. Lett. 14, 194 (1965); ibid 22, 290 (1966). Commins, Jackson, DeMille, Am. J. Phys. 75, 532 (2007). Gabrielse Why Use a Molecule?  To Make Largest Possible Electric Field on Electron

Tl atom (best EDM limit till YbF) ThO molecule

Elab123 kV/cm  E eff  72 MV/cm EGlab100 V/cm  E eff  100 V/cm

Molecule can be more easily polarized using nearby energy levels with opposite parity (not generally available in atoms) Gabrielse  Detect the Energy Difference  S two states evolve differently in time  g / 2  i  E t /hbar   S e de d e / 2 Gabrielse Still, the EDM Gives Tiny Shift of Energy Levels 2 mHz E 7  1018 eV 7  1027 GeV Not so easy to resolve 7  1030 TeV

To detect  let a prepared wave function evolve for time T large as | (0) |1 | 2  |  (T) |1ei | 2  possible E   T  T1.1 ms   11  106  0.6  10  3 degrees

Example is for an electron edm equal the ACME upper limit. Gabrielse Experiment in Two Labs – 100 Meters Separated Harvard Jefferson Building Harvard LISE Building

ThO Source and Interaction Chamber 100 m optical fibers (2 floors down)

Lasers, Iodine Clock, Comb Gabrielse ThO Molecular Beam Pulse Tube Cooler Molecular Beam “Interaction Source Region”: E- field plates inside, B- field shields Pulsed and coils YAG outside

Prep Lasers Probe Lasers

Lasers 100m away

34 Gabrielse Magnetic Field Coils and Shielding

mu metal 5 shields endplates (no shown) ~ 10-5 ThO beam shielding

Interaction Cos(theta) chamber coils to inside provide transverse B field 200 mG with uniformity of 10-3 over 26 cm Gabrielse Detect the Tiny Phase Shift  Interference set by choice set by choice of direction of of dark state the first of the two orthogonal detection laser polarizations

m1  eio m  1 m1  ei ()o 1   m  1 2 2

(  B  d E) 

 maximize sensitivity to  d E   11  106 Gabrielse Detecting an EDM

ground state superposition evolve: E + combine emit edm

E B cold electric field plates light ThO magnetic field detector source apparatus control and data acquisition Gabrielse Total Phase Equation:

, ,

= + Δ + + single+ block Parity sum (NEB) Derived quantities 10 blocks averaged

m t ) + + + Bnr g + θnr rad 3 ± 5 x 10-5 rad phase phase ( + + - B0 g m t block (~1 min) + - + Bleak g m t

) 392 ± 5

0 rad + - - x 10-5 rad

D phase ( - + + Bnr g m t D block (~1 min) - + - B0 g m t )

- - + de Eeff t rad ??? ± 5 x 10-5 rad - - - B0 η Enr m t phase (

block (~1 min) single block Gabrielse 10 blocks averaged )

rad -1530 ± 5 x 10-5 rad phase phase (

block (~1 min) Parity sum (NEB) Derived quantities )

m t rad -3590 ± 5 + + + Bnr g + θnr x 10-5 rad phase phase (

+ + - B0 g m t

m t ) B g rad + - + leak -2 ± 5 x 10-5 rad + - - 0 phase ( D block (~1 min) - + + Bnr g m t

D )

m t rad - + - B0 g 4 ± 5 x 10-5 rad phase phase ( - - + de Eeff t

block (~1 min) - - - B0 η Enr m t )

rad -1 ± 5 x 10-5 rad phase phase (

block (~1 min) Gabrielse Constraining New Physics on the 1 to 3 TeV ScaleGabrielse difficult to suppress for weak interactions new CP violating phase ~4/137

mass scale of prefactor new particles

couples to weak interaction via conservative n=1 or n=2 loop diagrams 3 TeV 1 TeV

Probing same mass scale as the LHC Gabrielse We need molecular theory to get the effective electric field

We actually constrain the EDM and CS

Assuming d=0 Gabrielse New ACME Electron EDM Measurement

New ACME Result Gabrielse How Big is 8 x 10-29 e cm? How sensitive was our princess Scale size of the polarization cloud to the hidden pea? around the electron  earth

Shift in earth center by 2 nm

earth-sized polarization cloud around electron (scale classical electron radius) Gabrielse Relationship to LHC Physics The LHC is exciting and important but EDMs also play a role • should get an improved electron EDM on the LHC time scale • If the LHC sees new particles, is CP violation involved? • If the LHC sees nothing, EDM game is the only one in town

• Would be great to use LHC results and ours together to see what we have learned together about Standard Model extensions Gabrielse

https://twiki.cern.ch/twiki/pub/AtlasPublic/CombinedSummaryPlots/AtlasSearchesSUSY_SUSY2013.pdf Gabrielse Gabrielse Testing the Standard Model’s Fundamental Symmetry

and

Comparing Antimatter-Matter Gravity Gabrielse Single Particle Measurements Have Three Big Advantages

Can be done with antiparticles

Can reach a much higher precision

Direct measurement  same measurement and apparatus is used with a particle and antiparticle Gabrielse Most Stringent Tests of the Standard Model (and Gravity) with Antiprotons

Q/M of Antiproton and Proton – most stringent test of the Standard Model’s CPT theorem with baryons

Comparison of Antiproton and Proton Gravity

680 Times Improved Comparision of the Antiproton and Proton Magnetic Moments Gabrielse Embarrassing, Unsolved Mystery: How did our Matter Universe Survive Cooling After the Big Bang?

Big bang  equal amounts of matter and antimatter created during hot time As universe cools  antimatter and matter annihilate

Big Questions: • How did any matter survive? • How is it that we exist? Our experiments are looking for evidence of any way that antiparticles and particles may differ Gabrielse Our “Explanations” are Not so Satisfactory Baryon-Antibaryon Asymmetry in Universe is Not Understood Standard “Explanation” Alternate • CP violation • CPT violation • Violation of baryon number • Violation of baryon number • Thermodynamic non-equilibrium • Thermo. equilib. Bertolami, Colladay, Kostelecky, Potting Phys. Lett. B 395, 178 (1997)

Why did a universe made of matter survive the big bang? Makes sense look for answers to such fundamental questions in the few places that we can hope to do so very precisely.

Bigger problem: don’t understand dark energy within 120 orders of magnitude _ _ Gabrielse Why Compare H and H (or P and P)?

Reality is Invariant – symmetry transformations P parity CP charge conjugation, parity CPT charge conjugation, parity, and time reversal

CPT Symmetry  Particles and antiparticles have • same mass • same magnetic moment • opposite charge • same mean life  Atom and anti-atom have  same structure Looking for Surprises • simple systems • reasonable effort • extremely high accuracy • FUN • comparisons will be convincing Gabrielse Comparing the CPT Tests Warning – without CPT violation models it is hard to compare CPT Test Measurement Free Accuracy Accuracy Gift _ -18 -3 15 K0 K0 2 x 10 2 x 10 10 Mesons

e+ e- 2 x 10-12 2 x 10-9 103 Leptons improve with _ antihydrogen P P 9 x 10-11 9 x 10-11 1 baryons 3 fundamentally different types of of typesparticles different 3 fundamentally Gabrielse I Came to CERN First in 1986 to Compare the Antiproton and the Proton

 Started cold antiproton and antihydrogen physics

 Now a dedicated storage ring and 6 international collaboration (still amazes me) Gabrielse Accumulating Low Energy Antiprotons: Basic Ideas and Demonstrations (1986 – 2000) TRAP Collaboration 1 cm at CERN’s LEAR magnetic field

21 MeV antiprotons 10-10 energy _ + _ reduction • Slow antiprotons in matter Now used by 5 collaborations • Capture antiprotons in flight at the CERN AD • Electron cooling  4.2 K ATRAP, ALPHA, ASACUSA, -17 • 5 x 10 Torr AEGIS, BASE Gabrielse Highest Precision Test of Baryon CPT Invariance  by TRAP at CERN

q/ m (antiproton)  0.99999999991(9) 9 1011  90ppt q/ m (proton)

(most precise result of CERN’s antiproton program)

Goal at the AD: Make CPT test that approach exceed this precision Gabrielse We Improved the Comparison of Antiproton and q/ m (antiproton) 6  0.99999999991(9) Proton by ~10 q/ m (proton) 9 1011  90ppt most stringent CPT test with baryons

6 105

100 antiprotons and protons G. Gabrielse, A. Khabbaz, D.S. Hall, C. Heimann, H. Kalinowsky, W. Jhe; Phys. Rev. Lett. 82, 3198 (1999). Gabrielse Seek to Improve Lepton and Baryon CPT Tests

antiproton moment

ATRAP members

 2 2  R[H]m[][][ e q e  q[][p  1 m e ] / M p]       R[H] m[][][ e q e  q[ p][  1 m e ]/ M p] Gabrielse Gabrielse Direct Comparison of Antimatter and Matter Gravity

Does antimatter and matter accelerate at the same rate in a gravitational field?

gantimatter  g matter

acceleration due to gravity acceleration due to gravity for antimatter for matter Gabrielse The Most Precise Experimental Answer is “Yes”  to at lease a precision of 1 part per million

2 Gravitational red shift for a clock: //   g h c  Antimatter and matter clocks run at different rates if g is different for antimatter and matter

 U Hughes and Holzscheiter, c 3(  1) 2 Phys. Rev. Lett. 66, 854 (1991). c c grav. pot. rnergy difference for tensor gravity between empty flat space time (would be 1 for scalar gravity) and inside of hypercluster of galaxies Experiment: TRAP Collaboration, Phys. Rev. Lett. 82, 3198 (1999). c 1010     1  (  10  6 ) c Gabrielse Gravity and Antihydrogen Gabrielse May be Hard to Get the Part per Million Precision of the Redshift Limit with Antihydrogen and Hydrogen

gantimatter  g matter

 Gravitational redshift: c 1010     1  (  10  6 ) c

Worthy goal for AEGIS and GBAR  can they get a part per million

ALPHA trapped antihydrogen released (2013):  110 (108 times less precise) Gabrielse Sometimes It is Said that this Redshift Measurement is not so Valid Because it “Assumes CPT Invariance”

• Does not assume CPT invariances in the gravity sector of course

• Only assumes that CPT violations in the Standard Model (if they exist) do not cancel the CPT violations in gravity (if they exist)

• Does not seem likely to me that CPT violations in the Standard Model would be just the right size to cancel differences in gravitational redshifts of the antiproton and proton (at our location in space-time). Gabrielse Antiproton Magnetic Moment Gabrielse Proton and Antiproton Magnetic Moments are Much Smaller than the Electron Moment

Harder: nuclear magneton rather than Bohr magneton Gabrielse Phys. Rev. Lett. 180, 153001 (2012)

Earlier contributions

Later measurement with similar methods Gabrielse Gabrielse Resonance Lines to Determine the “Two” Frequencies square of extra width

Brown-Gabrielse Invariance Theorem Gabrielse First One-Particle Measurement of the Antiproton Magnetic moment 680 times lower than previous Gabrielse 680 – Fold Improved Precision

ASACUSA 680

2013

plausible aspiration

ATRAP, Phys. Rev. Lett. (2013). Gabrielse Proton Spin Flip Report

Similar proton result from Mainz group in same issue Gabrielse Gabrielse Antihydrogen Hope for the Future

Note: no scientifically interesting tests of fundamental symmetries have yet taken place with antihydrogen – beware the hype Gabrielse Proposal to Trap Cold Antihydrogen – 1986

• Produce cold antihydrogen from cold antiprotons “When antihydrogen is formed in an ion trap, the neutral atoms will no longer be confined and will thus quickly strike the trap electrodes. Resulting annihilations of the positron and antiproton could be monitored. ..." • Trap cold antihydrogen • Use accurate laser spectroscopy to compare antihydrogen and hydrogen “For me, the most attractive way ... would be to capture the antihydrogen in a neutral particle trap ... The objective would be to then study the properties of a small number of [antihydrogen] atoms confined in the neutral trap for a long time.” Gerald Gabrielse, 1986 Erice Lecture (shortly after first pbar trapping) In Fundamental Symmetries, (P.Bloch, P. Paulopoulos, and R. Klapisch, Eds.) p. 59, Plenum, New York (1987). Use trapped antihydrogen to measure antimatter gravity Gabrielse Most Trapped Antihydrogen in Its Ground State

5 +/- 1 ground state atoms simultaneously trapped

ATRAP, “Trapped Antihydrogen in Its Ground State”, Phys. Rev. Lett. 108, 113002 (2012) Gabrielse ATRAP Collaboration Gabrielse Ultimate Goal: Hydrogen 1s – 2s Spectroscopy (or similar tests of ground state hyperfine structure)

(Haensch, et al., Max Planck Soc., Garching) http://www.mpq.mpg.de/~haensch/hydrogen/h.html

Many fewer antihydrogen atoms will be available Gabrielse

Two Methods Produce Slow Antihydrogen

1. In a nested Penning trap, during positron cooling of antiprotons Device and technique – ATRAP Used to produce slow antihydrogen – ATHENA and ATRAP

Variations: Basic (ATRAP initially, ATHENA-ALPHA) Driven (ATRAP before 2007) Adiabatic well depth change (ATRAP 2007)

2. Laser-controlled resonant charge exchange ATRAP Anti-H Method 1: Nested Penning Trap Gabrielse 3-Body “Recombination”

Nested Penning Trap 3-Body “Recombination” Positron Cooling of Antiprotons Gabrielse in a Nested Penning Trap p

e+

TRAP/ATRAP Develops the Nested Penning Trap Proposed nested trap as a way to make antihydrogen "Antihydrogen Production Using Trapped Plasmas" G. Gabrielse, L. Haarsma, S. Rolston and W. Kells Physics Letters A 129, 38 (1988) "Electron-Cooling of Protons in a Nested Penning Trap" D.S. Hall, G. Gabrielse Phys. Rev. Lett. 77, 1962 (1996) "First Positron Cooling of Antiprotons" ATRAP Phys. Lett. B 507, 1 (2001) Gabrielse Anti-H Method II: Antihydrogen Via Laser-Controlled Resonant Charge Exchange

852 nm

510.6 nm

ATRAP, Phys. Rev. Lett. 93, 263401 (2004) 1986 2012 Gabrielse 1 Collaboration  4 Collaborations Following the 1986 plan: Variations

cold antiprotons

cold antihydrogen colder antihydrogen

trap antihydrogen extract from trap

precise laser spectroscopy laser spectroscopy interferometry

ATRAP and ALPHA ASACUSA AEGIS Gabrielse Gabrielse First Generation Penning-Ioffe Apparatus Gabrielse

ATRAP – observed the production of antihydrogen atoms in the fields of a Ioffe trap (PRL 2008)

Less than 20 atoms were being trapped per trial

ALPHA – did similar production the following year

two directions

ATRAP ALPHA Try to make more atoms Try to detect fewer atoms

5 +/- 1 per trial 0.7 +/- 0.3 per trial Gabrielse 1.2 K Electrodes and Millions of Antiprotons

1.2 K Using Pumped Helium Gabrielse ATRAP  More Antiprotons, Much Colder, More Simultaneously Trapped Atoms

• Lowered electrode temperature to 1.2 K • Started measuring antiproton temperatures • Developed new pbar cooling methods

First antiprotons cold enough to centrifugally separate from the electrons that cool them Phys. Rev. Lett. 105, 213002 (2010).

Two new cooling methods for antiprotons -- embedded electron cooling -- adiabatic cooling Phys. Rev. Lett. 106, 073002 (2011).

 3 million antiprotons at 3.5 K Gabrielse Gabrielse Particle Physics at Low Energy Gerald Gabrielse Leverett Professor of Physics, Harvard University Spokesperson of the CERN ATRAP Collaboration Testing the Most Precise Prediction of the Standard Model  Electron magnetic moment Testing standard model extensions  Electron electric dipole moment Testing the Symmetries of the Standard Model  Q/M for the antiproton and proton  Antiproton and proton magnetic moments  Positron and electron magnetic moments (underway)  Antihydrogen and hydrogen structure (still in far future) Comparing Antimatter and Mater Gravity  Gravitational Redshift of the Antiproton and Proton Supported by US NSF and AFOSR Gabrielse Summary Low energy particle physics produces the most stringent tests of the standard model, its extensions and its fundamental symmetries - electron magnetic dipole moment - electron electric dipole moment - comparison of antiproton and proton charge-to-mass ratios - comparison of antiproton and proton gravity - comparison of antiproton and proton magnetic moments Antihydrogen – now have cold trapped antihydrogen atoms in their ground states, but not enough atoms yet – no interesting tests of fundamental symmetries yet, but big hopes for the future