1. Flavor Physics II Brendan Casey, Fermilab CINVESTAV 11/5/2013

2. Conclusions from yesterday Today: went through the historical progression that leads to our present understanding of flavor physics Next two days: will investigate how this ties into one of the most important scientific questions “Why are we here?” Thursday: will investigate different techniques to predict where to search for new physics B. Casey, 11/5/2013 2/59

3. Today Electroweak baryogenesis New sources of CP violation –In B physics –In EDMs B. Casey, 11/5/2013 3/59

4. What was Clinton talking about? It was just this week we had an amazing breakthrough in physics attempting to determine how life began on earth… Subatomic particles of matter, which normally under the laws of physics would be expected to cancel each other out… didn’t because they were slightly more positive than negative He’s correct but slightly out of context B. Casey, 11/5/2013 4/59

5. Clinton’s talking about here When we study CPV in quarks, we are usually looking here < one billionth of a second old Equal amounts of matter and antimatter Only matter B. Casey, 11/5/2013 5/59

6. Dirac’s Electron Dirac’s great success was the unification of quantum mechanics and Einstein's relativity. Dirac’s equation predicted new types of electrons. Once you have enough energy, you could produce pairs of these electrons (E=2mc 2 ) New types electrons have opposite charge: anti- electrons or positrons You can create electron-positron pairs, or if you bring an electron and positron together, they annihilate B. Casey, 11/5/2013 6/59

7. So what's the problem? The problem is how did we get here? If matter and antimatter are created in pairs, where is anti-CINVESTAV? If matter and antimatter annihilate, how did we ever survive 15 billion years or even 15 seconds without all the matter and antimatter canceling out? The fundamental laws of physics are supposed to explain the entire universe, big, small, slow, fast, old and new. But they predict that we shouldn’t exist. B. Casey, 11/5/2013 7/59

8. Enter Andrei Sakharov Father of the Soviet Hydrogen Bomb Later became a leading human rights activist and received the Nobel Piece Prize in 1975 “a spokesman for the conscience of mankind” In 1967 formulated the ‘Sakharov conditions’ for what needed to happen for the universe as we know it to have formed instead of annihilating itself. B. Casey, 11/5/2013 8/59

9. Sakharov’s conditions Baryon number violating processes (something that only makes matter or antimatter) B. Casey, 11/5/2013 9/59

10. Sakharov’s conditions Loss of thermal equilibrium (particles aren't able to communicate with each other) B. Casey, 11/5/2013 10/59

11. Sakharov’s conditions CP Violation (Harder for antimatter to get through the boundry) Loss of thermal equilibrium (particles aren't able to communicate with each other) Baryon number violating processes (something that only makes matter or antimatter) B. Casey, 11/5/2013 11/59

12. B. Casey, 11/5/2013 12/59

13. Thin film interference B. Casey, 11/5/2013 13/59

14. Thin film interference B. Casey, 11/5/2013 14/59

15. Thin film interference B. Casey, 11/5/2013 15/59

16. Thin film interference B. Casey, 11/5/2013 16/59

17. There was a boundary in the early life of our universe There was destructive interference in the boundary Some matter waves made it through but antimatter waves didn't B. Casey, 11/5/2013 17/59

18. What boundary? Main guiding principle of high energy physics is that at high enough energies, everything looks the same This translates into different epochs of time when the universe was at higher and higher temperatures all the way back to the big bang Epochs are characterized by unification of forces The universe comes in phases, just like ice, water, and steam B. Casey, 11/5/2013 18/59

19. What happens in a phase transition? B. Casey, 11/5/2013 19/59

20. Our model for how we got here Epochs of time where there were equal amounts of matter and anti-matter There were baryon violating processes but no excess is generated because matter and antimatter excess are in thermal equilibrium The universe begins to go through a phase transition. Our side of the phase starts growing in bubbles. Excesses of matter or antimatter that enter the bubble wall are no longer in thermal equilibrium so they do not necessarily annihilate. There is CP violating interference in the bubble wall that allows a little more matter to get through. This generates the matter asymmetry in the present epoch of the universe. B. Casey, 11/5/2013 20/5 9

21. Adding it all up at the electroweak scale B. Casey, 11/5/2013 21/59 1: Baryon number violating processes No problem with baryon or lepton violation at high temperature in Standard Model. B-L conserved. Sphaleron transitions shift baryon number into lepton number SU(3)xSU(2)xU(1) Potential energy Total baryon number (or lepton number) B L

22. Adding it all up at the electroweak scale B. Casey, 11/5/2013 22/5 9 2: Loss of thermal equilibrium Nature of the phase transition can be calculated once all parameters are fixed, including Higgs mass Low Higgs mass (<< 125 GeV) First order transition = bubbles Higgs mass = 125 GeV Second order transition = no bubbles For a SM with m(H) = 125 GeV, no loss of equilibrium. Can not generate a matter asymmetry at the electroweak transition. Conclusion changes if there are new particles at the TeV scale. 1 er order 2 do order

23. Adding it all up at the electroweak scale B. Casey, 11/5/2013 23/5 9 3: CP Violation Amount of CPV is given by the Jarlskog invariant ~area of the unitarity triangle Even though CKM phase is close to maximal, total effect is small due to small mass differences in first generation and small mixing angles of CKM matrix Can still assume there are new particles at TeV scale and calculate effect: Baryon to photon ratio predicted is 15 orders of magnitude smaller than measured! Need new particles and new CPV or you need to go to a higher phase transition (GUT) Mag(CPV) ≈ f(m 2 j -m 2 i ) × f(  ij ) × sin  CP

24. CPV in B s mixing 24/5 9 B. Casey, 11/5/2013 (WS Hou)

25. Dimuon charge asymmetry 25/5 9 B. Casey, 11/5/2013 t W W b s b s t W W b s b s t t B s mixing in the mirror

26. Measurement history at Dzero 1992: first internal note outlining measurement 1994: 7.3 pb -1 : A = (81-96)/(81+96) 1996: significant asymmetries observed due to asymmetries in range-out. –From then on, Dzero switches polarity every few weeks to enable this measurement 2003: analysis of ~100 pb -1 RunII data indicates we are competitive. Begin planning for a 1 fb -1 result. –Dimuon result. Single muon result ruled out because completely dominated by Kaon asymmetry 26/5 9 B. Casey, 11/5/2013 Iron toroid + -

27. Measurement history at Dzero 1 fb -1 result: –A SL = -(0.92 ± 0.44 ± 0.32)% –World leading measurement –Dominant error is now Kaon asymmetry determined using D*  D , D  K , K  X Raw asymmetry A = -(0.05± 0.13)% Kaon asymmetry A K = -(0.23 ± 0.08)% 27/59 B. Casey, 11/5/2013

28. 2010 Update Need a way to constrain the Kaon asymmetry Two samples: –Like-sign dimuon system = physics + Kaon –Single muon system: asymmetry is almost entirely from the Kaons Use the single muon system to make a high statistics measurement of the kaon asymmetry and subtract it from the dimuon asymmetry 28/5 9 B. Casey, 11/5/2013

29. Dimuon results A SL = (0.957±0.251±0.146)% Systematic error dominated by Kaon asymmetry –In dimuon analysis: 2.1% –In combined single and dimuon analysis: 0.15% Verified the B content by measuring the mixing probability in the first fb -1 data set –X = 0.136±0.001±0.024 –PDG: 0.1281± 0.0076 29/5 9 B. Casey, 11/5/2013

30. Final results with full dataset B. Casey, 11/5/2013 30/5 9 This is very nice but it is unconfirmed Adding other constraints brings the value closer to the SM

31. Another source of CPV: EDMs Some EDM PR What is an EDM Why is it important EDM experiments EDMs @ FNAL B. Casey, 11/5/2013 31/59

32. Nima at the Rockville Meeting B. Casey, 11/5/2013 32/5 9

33. More Nima B. Casey, 11/5/2013 33/5 9

34. B. Casey, 11/5/2013 34/5 9 (Klaus Kirch)

35. Isidori at ichep 2010, EDMs and Flavor B. Casey, 11/5/2013 35/5 9 Large B s CPV shrinks available parameter space Titanium neutron Mercury 10 -25 10 -30 Buras, Isidori, Paradisi arXiv:1007.5291 B s CPV

36. B. Casey, 11/5/2013 36/5 9

37. What is an EDM? B. Casey, 11/5/2013 37/59 Classical picture ala Maxwell: There is a fundamental electric charge. There is no fundamental magnetic charge. You have to have a North and South pole. Non-relativistic quantum mechanics ala Pauli: There is an electric charge that couples to the scalar field There is a magnetic spin that couples to the vector field. Classical to Quantum: charge goes to charge, North-South goes to Up-Down

38. Classical to quantum B. Casey, 11/5/2013 38/5 9 + - + - Magnetic dipole Electric monopole + + Electric dipole Classical extended objects Point particles with quantum numbers that have classical analogies

39. What is an EDM? B. Casey, 11/5/2013 39/5 9 Dirac’s electron: There is a fundamental degree of freedom associated with spin –Even though the electron is a point particle There is a new fundamental degree of freedom: antimatter –Dirac tried to explain this away using hole theory as simply the absence of charge. But his equation was right and he was wrong. There is a new fundamental degree of freedom: ‘electric spin’ …and it’s imaginary! –Dirac dismissed this because it was pure imaginary. –Is this another case where Dirac’s equation was right and he was wrong?

40. B. Casey, 11/5/ 2013 - p. 40/68 Dirac’s EDM

41. Imaginary charge Quantum imaginary charges are very important –They flip sign when you do a CP transformation, i.e. they violate CP –It is OK to be imaginary because we only measure their absolute value, but the interference they cause has measurable effects Question: What is the only particle we’ve discovered that seems to have intrinsic imaginary charge? – Disclaimer: Theorists would say this is arbitrary but that’s not fun. B. Casey, 11/5/2013 41/59

42. Imaginary charge Answer: the top quark B. Casey, 11/5/2013 42/5 9 t d W Top quark is responsible for all the CP violation we see in B and K mixing. –With the exception of our dimuon asymmetry OK, the b quark also has the same imaginary charge as the top. (same  ) –With the exception of the K  problem  –  i  t t s s d d W W t t b b d d W W b W u  –  i 

43. QCD’s EDM Here is a list of facts I haven't figured out yet: –Also turns out that QCD predicts an electric dipole moment for QCD objects –This naturally falls out of the QCD Lagrangian –The lack of EDMs is the ‘strong CP problem’ –You can cancel this term in the QCD Lagrangian with an Axion. –This also ties the question of EDMs to dark matter. B. Casey, 11/5/2013 43/5 9

44. What do EDMs look like? It can be a fundamental parameter just like spin and charge –Dirac’s EDM or QCD’s EDM (10 -16 e-cm) It can be something that couples to an electric field like an EDM would –Remember, spin is called spin because of the way electrons behave in a magnetic field B. Casey, 11/5/2013 44/5 9 Electron EDM generated by CKM 10 -38 e-cm Neutron EDM generated by CKM 10 -32 e-cm (Klaus Kirch)

45. What do EDMs look like? Since we are talking about loops, anything goes –This is where the new physics comes in B. Casey, 11/5/2013 45/5 9 For leptons: –Dirac EDM + CKM EDM –NP loops For nucleons and atoms: –Dirac EDM+QCD EDM+CKM EDM –NP interactions quark + loops (same as lepton) quark-quark quark-gluon nucleon-nucleon –This is complicated. But the take away message is you need several systems to interpret the limits. >N measurements for N sources of EDMs Not just about the best EDM limit (Michael Ramsey-Musolf)

46. Great, but why do we care? (I) We know we need new sources of CPV. –Flavor changing processes can’t generate enough matter But two anomalies are not yet understood –Our dimuons and the K  problem –B d has large SM background, B s doesn’t That’s why we searched there and that’s why we interpret our result as new physics –What if the new CPV is not flavor changing? B and K physics tell us nothing Would show up in EDMs –Particle’s magnetic moment has large SM background, particle’s EDM doesn’t Same smoking gun argument B. Casey, 11/5/2013 46/5 9

47. Neutral system Experiments B. Casey, 11/5/2013 47/59 Trap neutral system. Flip the E field and subtract the results. Main background (magnetic precession) cancels. Then spend a lifetime understanding the systematics (Kirch)

48. Charged particle systems B. Casey, 11/5/2013 48/5 9 problem: cant trap a charged particle solution: can store a charged particle. Look and see if things are still aligned when the particle comes back around again Are different ways of canceling out the main magnetic precession term and systematics. State-of-the-art is muon g-2 +

49. Results B. Casey, 11/5/2013 49/5 9

50. Some details Hg limit is 10 -29 but proton limit is only 10 -25, why? B. Casey, 11/5/2013 50/5 9 + - - + - - External E field internal E field Particles see a much smaller field

51. The right atoms Need atoms with weird shapes so everything won’t cancel –Octopole deformation Mercury is the best stable atom for this But there are even better atoms and isotopes that are unstable B. Casey, 11/5/2013 51/59

52. B. Casey, 11/5/2013 52/5 9

53. B. Casey, 11/5/2013 53/5 9

54. More details Fundamentally table top experiments –Order $1M Next gen neutron EDM –Order $100M for experiment –Order $1B if you also need a new spallation source Another problem –Spallation sources are designed as user facilities for material science –Not well matched to doing fundamental precision neutron science at the 10 -30 level B. Casey, 11/5/2013 54/5 9

55. Project X Have an opportunity to make a spallation source tailored to the needs of ultra-precision neutron experiments –This community is very interested Plus: B. Casey, 11/5/2013 55/5 9

56. Proton EDM We can put the proton EDM ring in the accumulator –This needs a very small fraction of the beam we already have. –Don’t even need Project X B. Casey, 11/5/2013 56/5 9

57. Where are we? Have a enormous program to look for new TeV particles at the LHC Have a broad program at Belle II and LHC to search for new CPV in flavor changing processes Have a broad program around the word to search for CPV in flavor conserving processes B. Casey, 11/5/2013 57/59

58. What this might look like B. Casey, 11/5/2013 58/5 9 Have the ability to confirm, seriously constrain, or possibly rule out electoweak baryogenesis as the source of the matter asymmetry in the universe with existing experiments or ones under construction

59. Conclusions for today Flavor physics is tied to one of the most important questions in science today –Why are we here? Leading theory is electroweak baryogenesis –Lack of new CPV, large Higgs mass, and no new particles at the LHC make this difficult to work Next step is to explore how this would work at the next phase transition –GUT scale B. Casey, 11/5/2013 59/5 9