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David Hitlin Caltech Let’s Celebrate Jonathan July 24, 2008

CP Violation. and. David Hitlin Caltech Let’s Celebrate Jonathan July 24, 2008. B A B AR was a great adventure for two decades, now nearly concluded

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David Hitlin Caltech Let’s Celebrate Jonathan July 24, 2008

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  1. CP Violation and David HitlinCaltechLet’s Celebrate Jonathan July 24, 2008

  2. David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  3. BABARwas a great adventure for two decades, now nearly concluded • This day, devoted to highlighting Jonathan Dorfan’s many contributions, is, of course, a most appropriate one to look back on BABAR and its accomplishments • Jonathan served as head of the PEP-II project and as BABAR ‘s Technical Coordinator, succeeding Vera Lüth • His leadership in these endeavors, as in many others, was characterized by his skill, drive, understanding of people, deal-making ability and his ability to keep his eye on the ball • The latter is perhaps best characterized by the BABAR/PEP-IImantra: “What is the effect of ……….. on the measurement of sin2b ?”, where ………….. could be • degree of mode suppression in the RF cavities • gauge of magnet power supply cables • length of the CsI(Tl) crystals • thickness of the drift chamber end plates • or any of a thousand other decisions we had to make David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  4. CP violation and baryogenesis • The experimental study ofCPviolation dates back to 1964, when Christensen, Cronin, Fitch and Turlay discovered that the decays of KLmesons violate CP invariance by ~2 parts per thousand • In 1967 Andrei Sakharov showed the connection between CP violation and the dominance of matter over antimatter in the universe • In the Big Bang there was, by assumption, an equal amount of matter and antimatter in the universe (i.e., the net baryon number of the universe was zero), but we now live in a matter universe • The Sakharov conditions for the disappearance of the antimatter: • Violation of Cand CPsymmetry – observed, allowed in the Standard Model • Baryon number-violating interactions -beyond the Standard Model • Departure from thermal equilibrium (an “arrow of time”) - inflation David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  5. Perils of Modern Living Harold P. Furth DOE ERDA Well up above the tropostrata There is a region stark and stellar Where, on a streak of anti-matter Lived Dr Edward Anti-Teller. Remote from Fusion's origin, He lived unguessed and unawares With all his antikith and kin, And kept macassars on his chairs. One morning, idling by the sea, He spied a tin of monstrous girth That bore three letters: A. E. C. Out stepped a visitor from Earth. Then, shouting gladly o'er the sands, Met two who in their alien ways Were like as gentils. Their right hands Clasped, and the rest was gamma rays. The New Yorker, 1955 David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  6. CP violation and baryogenesis • The annihilation of matter and antimatter in the very early universe was nearly complete: only a tiny fraction of the baryons escaped annihilation: • A quantitative measure of the process at early times is provided by the ratio of baryons to relic photons in the cosmic microwave backgroundnbaryons/nphotons= (5.1 +0.3-0.2)x10 –10 • The baryons that escaped annihilation were those that could not find a an antiparticle partner, the partner having preferentially decayed due to CP violation in the weak interaction • However, the expected Standard Model scale of CP violation is far too smallto produce this many baryons. At best, the Standard Model can producenbaryons/nphotons~ 10 –20 • Getting a clear handle on the precise strength of CP violation in KL decay was hard • because KL mesons are so light, it is difficult to connect the CP asymmetry measured at the meson level with the underlying strength at the quark level David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  7. The situation in the mid ’80’s • In 1981 Bigi and Sanda showed that a measurement of CP violation in B0 meson decay to CP eigenstates could be clearly interpreted, without theoretical uncertainties. • The prospect of a clean measurement in B0 decays was exciting; perhaps the Standard Model prediction of the strength of CP violation would fail • With the observation in ’83 of a long B meson lifetime by Mark II and MAC and in ’87 of substantial Bd mixing by ARGUS and UA1, one could contemplate measuring CP-violating asymmetries in B0 meson decays • Doing so would require flavor-tagging a B meson and then untangling mixed from unmixed decays, which could be done using B’s produced in e+e- annihilation or in hadronic collisions • However, at least 107-108Bpairs would be needed, a 2-3 order of magnitude increase in the existing data sample • Exploiting the quantum correlations of pairs produced in ϒ(4S) decays in e+e- seemed like a particularly elegant approach, but separating the decays was difficult as the B0lifetime in the laboratory corresponds to 19μm David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  8. The Gold Rush • This led to at least 21e+e-B Factory concepts and proposals (19 ϒ(4S) + 2 Z0)and several hadronic machine approaches (HERA-B, …….) • Oddone’s concept of using an asymmetric e+e- collider to boost the distance between the two decay vertices o an measurable regime was, in the end, the most successful approach • Two colliders, PEP-II and KEKB, were ultimately built David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  9. The ¡ resonances ine+e-annihilation: non-relativistic atomic systems Mϒ(4s) = 10.5794 + 0.0012 GeV G¡(4s) = 20.5 + 2.5 MeV A practical application of EPR David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  10. Motivation for B0 meson CP Violation measurements • Since CP violation is a necessary ingredient to produce a baryon asymmetry, and since the theoretical strength of CP violation in the three generation Standard Model is numerically insufficient to produce the observed asymmetry, it was hoped that a measurement of a CP-violating asymmetry that could be unambiguously related to the Standard Model CP phase would produce a surprise • The result was that the Standard Model phase produces exactly the needed amount of CP violation for B meson decays to pass the overconstrained Unitarity Triangle tests • Thus at this point, experimentally the Standard Model does not have the strength of CP violation to produce the observed baryon asymmetry • How do we measure the strength of CP violation in the Standard Model? David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  11. The B Unitarity Triangle • The CKM matrix describing the transitions among the three quark generations is unitary • There are six unitarity relations • The most useful unitarity condition is: • The sides of the unitarity triangle are determined by measurements of the magnitudes of CKM matrix elements • CP-violating asymmetries in B0decays to CPeigenstates measure the angles of the unitarity triangle, thereby providing an overconstrained situation and thereby a unique test of the Standard Model in the CKM sector David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  12. David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  13. i f To measure a phase, you need interference of two amplitudes CP violation can arise due to interference between two amplitudes with different phases - a weak phase f that changes sign under CP and a strong phase dthat is invariant under CP . A1= | A1| e i1e- i1 A1= | A1| e i1ei1 CP i f A2= | A2| e i2ei2 A2= | A2| e i2e- i2 David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  14. The Unitarity Triangle in 1990 Dib, Dunietz, Gilman and Nir, Phys.Rev D41, 1522 (1990) David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  15. Overview of the analysis Reconstruct exclusive B decays to CP eigenstates and flavor eigenstates and tag the flavor of the other B decay Measure Dz between BCP and Btag to determine the signed time differenceDt between the decays Determine theresolution functionfor Dz David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  16. USA [36/253] California Institute of Technology UC, Irvine UC, Los Angeles UC, San Diego UC, Santa Barbara UC, Santa Cruz U of Cincinnati U of Colorado Colorado State Elon College Florida A&M U of Iowa Iowa State U LBNL LLNL U of Louisville U of Maryland U of Massachusetts, Amherst MIT U of Mississippi Mount Holyoke College Northern Kentucky U U of Notre Dame Ohio State U U of Oregon U of Pennsylvania Prairie View A&M Princeton SLAC U of South Carolina Stanford U U of Texas at Austin U of Texas at Dallas Vanderbilt U of Wisconsin Yale Italy [12/89] INFN, Bari INFN, Ferrara Lab. Nazionali di Frascati dell' INFN INFN, Genova INFN, Milano INFN, Napoli INFN, Padova INFN, Pavia INF, Pisa INFNN, Roma and U "La Sapienza" INFN, Torino INFN, Trieste The Netherlands [1/5] NIKHEF Norway [1/2] U of Bergen Russia [1/7] Budker Institute, Novosibirsk United Kingdom [10/71] U of Birmingham U of Bristol Brunel University U of Edinburgh U of Liverpool Imperial College Queen Mary & Westfield College Royal Holloway, University of London U of Manchester Rutherford Appleton Laboratory The BABAR Collaboration 10 Countries73 Institutions521 Physicists Canada [4/15] U of British Columbia McGill U U de Montréal U of Victoria China [1/5] Inst. of High Energy Physics, Beijing France [5/51] LAPP, Annecy LAL Orsay LPNHE des Universités Paris 6/7 Ecole Polytechnique CEA, DAPNIA, CE-Saclay Germany [3/23] U Rostock Ruhr U Bochum Technische U Dresden A snapshot David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  17. TheBABARDetector 1m Si Vertex-Tracker,Drift Chamber,DIRC (Cherenkov), CsI-Calorimeter, Superconducting Coil, Iron Yoke + RPCs/LSTs David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  18. The PEP-II Asymmetric B Factory Final collisions 12:43pm,Monday 7 Apr 2008 David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  19. The need for speed David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  20. A tagged event David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  21. BABAR employed blind analysis and sophisticated maximum likelihood techniquesto extract maximum information from the datain an unbiased manner David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  22. sin2b in charmonium modes David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  23. Measuring the Unitarity Triangle angles David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  24. sin2a and g David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  25. Unitarity triangle constraints: sin2, sin2 measurements The CKM matrix passesthe unique, new overconstrained tests David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  26. The Unitarity Triangle deconstructed Tree level Without sin2b All measurements except sin2b Tree-dominated measurements Mixing Loop dominated CP-violating measurements Loop (mixing)-dominated measurements David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  27. Not even wrong!

  28. It may not be quite so simple…… _ • There are discrepancies in CP asymmetries in bsssloopdecays • There are other hints that there could be additional phases, i.e., that there is more in the flavor sector than the three generation Standard Model • Four generations can amplify the baryogenesis effect to the needed level: Hou (arXiv:0803.1234 [hep-ph] ) and can explain the various anomalies seen:Soni, Alok, Giri, Mohanta and Nandi (arXiv:0807.1971 [hep-ph] ) SuperB, with a 100x larger data sample, will resolve these issues, and allow us tounderstand the flavor sector of New Physics found at LHC David Hitlin "Let's Celebrate Jonathan" July 24, 2008

  29. The bottom line • BABAR hastested the Standard Model in unique ways by finding and then deeply exploring CP violation in the B meson system • BABAR has also done lots of physics beyond CP violation: • Many other B decay studies, including other hadronic, leptonic and semileptonic decays and rare loop-dominated processes • Weak decays of charm, including long sought evidence for mixing • t decays • New hadronic states, some unexplained in QCD • And just recently, the discovery of the hb, the ground state of the system as of last week, 324 publications in refereed journals: PRL, PRD, NIM David Hitlin "Let's Celebrate Jonathan" July 24, 2008

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