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Blair Ratcliff Stanford Linear Accelerator Center

Physics Results with RICH Counters. Outline: Introduction CP Violation in the B Sector The Search for Exotic Baryons Progress in Neutrino Physics Summary. 5 th International Workshop on Ring Imaging Cherenkov Counters. Blair Ratcliff

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Blair Ratcliff Stanford Linear Accelerator Center

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  1. Physics Results with RICH Counters • Outline: • Introduction • CP Violation in the B Sector • The Search for Exotic Baryons • Progress in Neutrino Physics • Summary 5th International Workshop on Ring Imaging Cherenkov Counters Blair Ratcliff Stanford Linear Accelerator Center

  2. Introduction-I • RICH Conference Tradition • Review Physics Impact of RICH Technique • A cause for celebration: Use of RICH has become common. •  Physics needing high quality PID • Flavor Physics and CP violation studies • Hadron Spectroscopy and the search for exotics • e/p separation in Heavy Ion Physics • Physics on a massive scale for cosmic ray and neutrino studies. • Technical Developments • Familiarity: Now a proven technique

  3. Introduction-II

  4. Introduction-III

  5. Introduction-IV • Apology: Extremely Broad Physics Range…way too many topics to even begin to cover them all. • Fortunately…Several physics topics have been addressed here both in review talks and more specific contributed detector/experiment talks. • Astroparticle/Neutrino Physics (Greg Hallewell + the Astroparticle Contributed session) • Heavy Ion Physics (Itzhak Tserruya) • Hadron Spectroscopy (see especially the Contributed talks in the session on “RICH at fixed target experiments” ) • Many thanks to the ICEHP04 speakers. Please see their wonderful talks for more details. Special thanks as well to J. Richman, D. MacFarlane, and M. Giorgi • Will concentrate on three areas that have had especially exciting results in the last two years….even so only a few specific topics from these areas can be covered: • B Flavor Physics (The Experimental Status of CP Violation) • The search for unusual hadrons and exotics (Do Pentaquarks exist?) • A brief update on Neutrino Physics

  6. Experimental Status of CPV in the B Sector • Tremendous progress since first observation of CPV in 2001 by BaBar and Belle. • Sin 2b0 is only the beginning: CP violation in B decays is not simply a single discovery, but a broad physics program! • First precise test of CKM picture. Now looking for small corrections rather than alternatives. • The search for new physics • Serious attack on all angles and sides of the unitary triangle. • New modes of CP violation: Discovery of direct CPV in B decays (2004). • Regarding the role of RICH: • High quality PID essential both for tagging and final state separation.

  7. SVD1 SVD2 Belle Detector SC solenoid 1.5T Aerogel Cherenkov cnt. n=1.015~1.030 CsI(Tl) 16X0 3.5GeV e + TOF counter 8GeV e - Tracking + dE/dx small cell + He/C2H5 ⇦+113/fb SVD2 Si vtx. det. 3 lyr. DSSD μ/KL detection 14/15 lyr. RPC+Fe ⇦140/fb SVD1

  8. L(K) LR(K)= L(K)+L(π) Particle Identification at Belle p/K/π separation is based on Likelihood ratio:

  9. BaBar Detector Instrumented Flux Return 1.5 T Solenoid DIRC thickness: 8 cm radial incl. supports 19% radiation length at normal incidence DIRC radiators cover: 94% azimuth, 83% c.m. polar angle DIRC Radiators Drift Chamber e+ (3.1 GeV) ElectromagneticCalorimeter e– (9.0 GeV) Silicon Vertex Detector DIRC Standoff Boxand Magnetic Shielding

  10. Hadronic PID at BaBar Npeand resolution per track (di-muons) vs. polar angle: Fully corrected efficiency/mis-id matrix for a standard selector. Bands represent uncertainties from control samples. Mis-id rates can be tuned down to ~1% over most of momentum space. s(Dqc,) = 2.4 mrad

  11. Delivered Recorded Continuum 300 250 200 150 100 50 0 10/11/04 9/11/00 1/21/02 5/3/99 6/2/03 B Factory Luminosities-Summer 2004 Total 244(BaBar) + 286(Belle) fb-1 = 0.530 ab-1!!

  12. CP Violation-A Brief Overview • CP violation can be observed by comparing decay rates of particles and antiparticles • The difference in decay rates arises from a different interference term for the matter vs. antimatter process. Analogy to double-slit experiment: Classical double-slit experiment: Relative phase variation due to different path lengths: interference pattern in space source B system: extraordinary laboratory for quantum interference experiments: many final states, multiple “paths.”

  13. Conditions for CP violation Two amplitudes, A1 and A2, with a relative CP-violating phase (f2) only No CP violation: the magnitudes of A and A are the same! • Two amplitudes, A1 and A2, with both a relative CP-violating phase and CP-conserving phase (d2).  Now have CP violation!

  14. Looking for the perfect way to study CP violation In the SM, the CKM matrix is the only source of CP violating phases.

  15. + phases CKM and unitarity conditions Unitarity Relations

  16. First Observation of Direct CPV in B decays (summer 2004) AKp=-0.101±0.025±0.005 3.9s 4.2s ± Average:AKp=-0.114±0.020 (~5.7s)

  17. Compilation of other Direct CP searches

  18. Measuring time-dependent CP asymmetries z FlavorTagging Tag vertex reconstruction Dz Exclusive B meson and vertex reconstruction Start the clock “Typical” Tagging performance (BaBar): Q = 30.5% • ps ~ 170um • 1.6 ps (tB) ~ 250 um • The asymmetric beam energies of the B-Factories allow the measurement of quantities that dependon decay time.

  19. Calculating the CP Asymmetry General Form

  20. The“Golden” modes: the magic of having just one direct decay amplitude • If CP violation is due to interference between mixing • and one direct decay amp: • Pure sin(Dm t) time dependence • No dependence of asymmetry on hadronic physics For the modes BJ/y KS (J/y KL)

  21. sin2b results from charmonium modes bkg Limit on direct CPV Belle 2003 BABAR 2004

  22. Results on sin2b from ccs, dcc modes

  23. sin2β, cos2β and CKM constraints BABAR cos2β < 0 cos2b < 0 ruled out at 87% CL by s- and p-wave interference in angular analysis of BJ/yK*0 (KSp0) cos2β > 0 CKM fit to indirect constraints overlaid with sin2βWA measurement

  24. A better approach to measuring sin2? B  rr decays Extraction of a similar to pp, but with advantage of smaller Penguin pollution: BABAR Moriond QCD04

  25. Results for sin2eff from B   decays BABAR: Updated for ICHEP04 BABAR Belle: PRL 93 (2004) 021601 >3s discrepancy between BABAR & Belle

  26. Summary of constraints on a BABAR & Belle combined Mirror solutions disfavored

  27. Do and yield the same sin2b ? The Standard Model Still Reigns!Is there anything beyond?

  28. In SM interference between B mixing, K mixing and Penguin bsss or bsdd gives the same e-2ib as in tree process bccs.However loops can also be sensitive to New Physics! sin2b and.... and.... New phases from SUSY?

  29. 2.7s from s-penguin to sin2b (cc) 2.4s from s-penguin to sin2b (cc) Results on sin2b from s-penguin modes All new! All new!

  30. 3.6s from s-penguin to sin2b (cc) Averages for sin2b and s-penguin modes No sign of Direct CP in averages

  31. CPV In B Physics…Summary • Tremendous progress by B Factories since first observation of CPV in 2001. Competetive experiments have been a strong plus. • CP violation in B decays is not simply a single discovery, but a broad physics program with many overlapping experimental results! • Precise measurement of Sin 2b=0.7260.037 from charmonium modes. • 3.6s discrepancy between charmonium and s-penquin modes. New Physics? • Serious attack on all angles and sides of the unitary triangle. Quantitative measurement(2004) of a(2 ) • New mode of CP violation: Discovery of direct CPV in B decays (2004). Outlook The increasing data samples from existing B-factories may very well provide convincing evidence for NP by ~2009! Unraveling full physics impact probably requires ~50-100 times more luminosity Motivates New Super-B Factory And Next Generation Hadronic Experiments

  32. Next Generation Experiments at Hadron Machines LHCb Layout From 2009 From 2007 • Purpose is to collect large samples to over-constrain Unitarity Triangle and search for New Physics.

  33. Next Generation Experiments at B-Factories? • Proposed New Super B Factory Machines at KEK/SLAC with • L~1-2x1035(KEK) ~2010? • L~5-7x1035 (PEP) ~2012?

  34. Exotic Hadron Spectroscopy-I • “Ordinary” Hadrons  (qqq or ) explain most of experimentally observed hadron spectrum. • However, QCD other “non-forbidden” states expected: • Multi-quark states (q ≥ 4); e.g., qqqqq; qqqq • Glueballs (e.g, gg,ggg) • Hybrids (e.g., qqg,qqqg) • Long experimental history some evidence for extra-ordinary states but difficult to interpret: • Light scalar mesons…too many states. • Threshold enhancements…are they resonant?

  35. Exotic Hadron Spectroscopy-II • Recent data have sparked renewed interest: • Pentaquarks (+(1540);--(1862); c+(3099)) • X(3872) • DsJ(2317); DsJ(2460); DsJ(2632) • Threshold enhancements in pp;p • Complicated experimental situation: • Varying production channels, energy ranges etc. • Range of detection methods, only some with RICH • Excellent PID is necessary in some cases and powerful in others but is not available in all experiments • Look at one topic today • Does the +(1540) Pentaquark exist?

  36. Some Early History  Many searches from late 60’s onwards for s = +1 baryon resonance production (the Z’s)in K+N scattering experiments. Nothing observed.  Summary on s = 1 baryon resonance searches was dropped from PDG as of 1986 with the following comment: “The general prejudice against baryons not made of three quarks and the lack of any experimental activity in this area make it likely that it will be another 15 years before the issue is decided.” PDG’s prediction: the pentaquark issue cannot be settled until  1986 + 15 = 2001 So it is past time to find something (or not)!

  37. Pentaquark Revival – The Q+Prediction D. Diakonov, V. Petrov, and M. Polyakov, Z. Phys. A 359 (1997) 305. A chiral soliton model for an anti-decuplet of 4 quarks plus an anti-quark gives specific estimates for masses and widths. The baryons at the corners are exotic. Splitting ~180 MeV Input S The lowest mass object which they called the Z+ (now called Q+) ispredicted to be: • Exotic: S=+1 • Low mass: 1530 MeV • Narrow width: ~ 15 MeV • JP=1/2+ I3

  38. First Evidence for the Q+: • LEPS at Spring-8 in M= 1540±10±5 MeV  < 25 MeV at 90% C.L. Bump significant claimed as 4.6s Minimum 5 quark content (uudds)  Mass and width consistent with chiral soliton model prediction.

  39. More Evidence for Q+(1540) e.g. A Plethora of Q+ Claims Followed-e.g., CLAS SAPHIR CLAS M(nK+) M(nK+) M(nK+) (fit) fit

  40. Summary of Positive Claims forq+

  41. Inconsistencies in Mθand Γθ? (LEPS) M(nK+)≠ M(pKs)? Width of θ+(1540)? • Two “positive” experiments: HERMES: Γθ= 17 9  2 MeV ZEUS: Γθ= 8  4 MeV • K+N PWA indicates Γθ< 1 MeV

  42. However, there are now many high statistics negative resultse.g., For the Ksp mass distributions seen in BaBar- the Lc is the only clear structure 1.4 - 5.4 GeV/c2 1.44 – 1.60 GeV/c2 Observed Ratio (Q+(1540)/ L*(1520)) <0.01 at 90% c.l. Lc Q+(1540) 1.6 – 1.8 GeV/c2 1.8 – 3.0 GeV/c2 Lc (~98,000 evts)

  43. Examples of Negative Results forq+-Belle 155fb-1 (1520) pK- pKS nothing m(GeV) Observed Ratio (Q+(1540)/L*(1520)) <0.02 at 90% c.l.

  44. M(pKs) More Examples of Negative Searches for q+ Aleph Hera-B M(pKs) Θ+(1540) M(pKs) CDF

  45. Summary of Negative Results • K+N Scattering results exclude Q+ widths greater than a few MeV. Widths less than about 1 MeV are possible.

  46. Negative Results in Perspective • Assume pentaquarks have J= ½ • expectBF(q5+pKs0) = 25% • expectBF(X5--X-p-) ~ 50% • BF for X5-, X50very unclear • If pentaquark production follows the trend for ordinary baryon production then we expect: • ~ 8x10-4Q5+per qq event • ~ 4x10-5X5--per qq event • Limits are below expectations; • Q5+:1.1x10-4 (G = 8 MeV) • X5--: 2x10-5 (G = 18 MeV) • But… • Most positive results at lower energies • How unusual is the exotic production mechanism? • L(1520) may not be a reliable guide

  47. So…do pentaquarks (especially the Q+(1540)) exist?? • “Expected” in QCD… Things that are not forbidden are compulsory! • “Predicted” by chiral soliton model, which also predicts other exotic states. • Spin, parity and mass may distinguish between models. • If it exists, can provide a clear window beyond the naïve quark model. • BUT…existence is an experimental question! • Experimental situation is, at best, equivocal. • Need new high statistics experiments, especially in electro & photo production. Look for new results soon from CLAS, HERMES, COSY-TOF, KEK E559.

  48. Update on Neutrinos By RICH02, it was clear that neutrinos oscillate.  It has now been further confirmed…. Neutrinos really do have small but finite masses! First clear confirmation of physics beyond SM A triumph for the large water RICH detectors!

  49. Major Neutrino Sources from Space • Solar: • From nuclear fusion • All ne • Low energy….En <20 MeV • Atmospheric: • From cosmic rays hitting the atmosphere p, He ne/nm 1/2 p nm m ne L ~ 20 km e Super-K ne Earth nm L ~ 104 km En~ 300 MeV - 2 GeV If Neutrinos have mass, a mixing formalism much like that for quark mixing applies, so that P(n1->n2) = sin22qsin2(1.27Dm2L/E)

  50. Super-Kamiokande 50K Ton H2O 1 km underground Full reconstruction Excellent m/e separation via ring width. SK-I: 1996-2001 Nov 2001 Accident SK-II:2003-2005 Period '96-'01 '03-'05 #PMTs 11,146 5,182 Photo Coverage 40 % 19 % Light yield ~6 p.e./MeV ~2.8 p.e/MeV Energy threshold 5.0 MeV 8.0 MeV

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