Neutrinos and the Case of the Missing Antimatter

1. Neutrinos and the Case of the Missing Antimatter Steve Boyd, University of Warwick

2. A little bit of history What are neutrinos? Where do they come from? Why study them? A recent surprise

3. CRISIS

4. Energy(Ra) ≠ Energy(Ac)+Energy(e)

5. Neils Bohr “At the present stage of atomic theory we have no arguments for upholding the concept of energy balance in the case of b-ray disintegrations.”

6. Wolfgang Pauli “Desperate remedy.....” “I do not dare publish this idea....” “I admit my way out may look improbable....” “Weigh it and pass sentence....” “You tell them. I'm off to a party”

7. Energy(Ra) = Energy(Ac)+Energy(e) + Energy(Neutrino)

8. What are neutrinos?

9. Electron, e - Tiny mass ( 1 )

10. Electron, e - Tiny mass ( 1 ) Electron Neutrino, ne 0 Very tiny mass (<0.0000001)

11. mass of a neutrino =

12. mass of an electron =

13. mass of a nice cup of tea =

14. Electron, e - Tiny mass ( 1 ) e e ne ne Electron Neutrino, ne 0 Very tiny mass (<0.0000001) Very tiny mass (<0.0000001)

15. e e In experiments neutrinos are NEVER seen. We can only detect them through the byproducts of their interactions with matter. Type of the charged particle detected used to infer the type of incoming neutrino.

16. - Electron, e Electron Neutrino, ne mass ( 1 ) - Muon, m Muon Neutrino, nm mass ( 200 ) - Tau, t Tau Neutrino, nt mass ( 3500 ) 3 Lepton Types, or Flavours

17. m t ne ne

18. m t ne ne

19. + Positron, e+ Electron Antineutrino, ne mass ( 1 ) + Muon, m+ Muon Antineutrino, nm mass ( 200 ) + Tau, t+ Tau Antineutrino, nm mass ( 3500 ) 3 Antileptons

20. Antimatter is not.... From Angels and Demons, Dan Brown, 2009

21. Matter Anti-Matter anti-quark quark Positive electric charge Negative electric charge Predicted by Dirac in 1928 Discovered by Anderson in 1932

22. Where do they come from?

23. Everywhere.... Sun Supernovae Atmosphere Reactors Accelerators

24. Geoneutrinos Here be dragons Earth's heat source is probably radioactive decay....which generates neutrinos

25. One cubic foot of space contains about 10,000,000 neutrinos left over from the Big Bang (maybe). From the Big Bang

26. They are present in vast numbers ≈ 5 billion per cm2 per second at the Earth

27. 5,000,000,000,000,000 solar n just went through you

28. So why don't we notice? n are almost ghosts. They interact extremely weakly with matter. To a neutrino a planet is mostly empty space.

29. Probability  5 x 10-13 = 0.00000000000005 ne

30. "The chances of a neutrino actually hitting something as it travels through all this howling emptiness are roughly comparable to that of dropping a ball bearing at random from a cruising 747 and hitting, say, an egg sandwich." Douglas Adams

31. Probability  2 x 10-13

32. e n p n e n p  e n p n e n p n e n p n e n p n e n p n

33. Why do we study them?

34. Probes of • environments that • we otherwise cannot • study • Cosmological and astrophysical probes IceCube Experiment

35. The Universe

36. The Universe but where is all the antimatter?

37. light matter light antimatter Equal amounts created - but no antimatter now - so matter and antimatter must behave differently after creation Understanding this is a Big Physics QuestionTM

38. How are we studying this?

39. The Sun is Broken!!! Ray Davis in his solar neutrino detector – Early 1970s

40. Less than expected The sun produces and Davis detected only ne Expected Measured Number n observed

41. e e ne ne Neutrino Oscillations THE discovery in neutrinos of the last 20 years A typical neutrino experiment

42. m e ne nm Neutrino Oscillations THE discovery in neutrinos of the last 20 years Neutrinos were changing flavour between sun and detector!

43. m e ne nm Fraction of nm Fraction of ne 1 Fraction of ne 0 Distance Travelled

44. Oh Come on, pull the other one! Q. How can a ne spontaneously turn into a nm?

45. Oh Come on, pull the other one! Q. How can a ne spontaneously turn into a nm? A. It's complicated...and can only be correctly described using the full mathematical machinery of quantum mechanics.

46. Oh Come on, pull the other one! Q. How can a ne spontaneously turn into a nm? A. It's complicated...and can only be correctly described using the full mathematical machinery of quantum mechanics. where Uai is a unitary matrix

47. In English this time? Q. How can a ne spontaneously turn into a nm?

48. e ne In English this time? Q. How can a ne spontaneously turn into a nm? A. The ne isn't a particle. It's three! ne≡ “that thing which was always produced/detected with an electron but is never observed itself”

49. e 50% n1 or e e = 30% n2 ne or e 20% n3 Quantum Stuff Posit three other particles with definite mass : n1, n2 and n3

50. m e ne nm n1,n2,n3 travels at different speeds Original n1,n2,n3 mixture Different n1,n2,n3 mixture Fraction of nm Fraction of ne Long journey