1 / 83

B Experiments

B Experiments. - “B Factories” -. - CP Violation & Flavor Physics -. Y.Sakai KEK. 28-Sep-2006, Nasu. Goal of B experiments. main. Step1. Discovery of CPV in B decay. 2001 summer !. Step2. Precise test of KM(CPV) and SM. Now. Step3. Search/Evidence for New Physics.

yitro
Télécharger la présentation

B Experiments

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. B Experiments - “B Factories” - - CP Violation & Flavor Physics - Y.Sakai KEK 28-Sep-2006, Nasu

  2. Goal of B experiments main Step1 Discovery of CPV in B decay 2001 summer ! Step2 Precise test of KM(CPV) and SM Now Step3 Search/Evidence for New Physics B decays  QCD/Lattice, New Resonances Also, excellent t/charm factory

  3. Symmetries Nature and its Law: ~ Symmetry = Beauty P, C, T : most Fundamental Symmetry P : Parity = Space inversion C : Charge conjugate ( Particle  Anti-particle; Quantum #) [Lagrangian  Hermitian conjugate] T : Time reversal [c-number  complex conjugate] CPT Theorem Lorentz invariant local quantum field theory  CPT symmetry Particle  Anti-particle: Mass and Lifetime are identical

  4. P& C Violation P Violation 1956: Lee-Yang predict P violation 1957: discovered by C.S.Wu in 60Co b-decay ［ＰＲ １０４，２５４］ ［ＰＲ １０５，１４１３］ Spin e Weak Interaction V-A P ６０Ｃｏ Spin e C violation nL-handed nL-handed Simple Illustration C L = -1 L = +1 P nR-handed Physical Particle  Anti-particle :CP

  5. CP Violation CPV: difference in behavior ofparticle and anti-particle 1964: discovered in K0 decay (J.Cronin, V.Fitch et. al.) ［ＰＲＬ １３，１３８］ Observation of KLp+p- CP Violation [K0-K0 mixing] _ [CP=+1] [CP=-1] K1=KS, K2=KL If CP conserves KSp+p- （CP＝＋１）, KLp+p-p0 （CP＝ー１） Branching fraction = 2.3x10-3

  6. Why CPV is Important ? Universe: almost “matter” only (no anti-matter) Big-Bang  N(particles) = N(anti-particles) Sakhalov’s 3 conditions (1967): 1. baryon number violation 2. CP violation 3. existence of non-equiblium CPV is a key for Existence of Universe & us ! Andrei Sakharov (1921-1989)

  7. Origin of CPV ? Kobayashi-Maskawa Ansatz (1973) Complex phase in the quark mixing matrix  source of CPV in Weak Interactions KM-phase Requires 3 (or more) generation of quarks • only 3 quaks (u, d, s) were known at that time ! • All 6 quarks are now discovered Essential ingredient of the Standard Model (SM)

  8. W- dj Vkj uk CKM matrix CKM matrix Weak Interaction (charged current) Wolfenstein representation + O(l4) • l = sinqc ) qc: Cabibbo angle

  9. 2 3 1 * Vtd Vtb * VudVub h (r,h) * Vcd Vcb f2 |Rb| |Rt| (a) (1,0) f3 f1 (b) (g) r 1 Unitarity Triangle CKM matrix: unitary V†V ＝ １ （S VijV*ik = dｊk ） j=1(d), k=3(b) (a) (b) (g) Normalize by V*cbVcd (=Al3)

  10. b top bottom charm strange d u c t s up down CPV: Why B ? Size of CPV in K: O(10-3) ~ small not enough information to confirm KM scheme Specialty of B long lifetime (~1.5 ps) Large B0-B0 mixing Various decay modes Sanda-Bigi-Carter (1980) Large CPV in B-system

  11. A B0 ｆｃｐ = c Vtd - t B0 A d b W W d b d Vtd t 0 d 0 d 0 d B B B Vcb J/y Initial: B0 b c B0 _ Vtb Vtb Vus    W B0 ｆｃｐ B0 KS d d B0 B0-B0 Mixing & CPV _ _ A Sanda Bigi Carter mixing Decay: A Interference Direct decay Mixing + Decay Weak Phase difference Oscillation Time dependent CPV

  12. 2ImlCP 1+ |lCP |2 S = q p A A lCP = |lCP |2 -1 |lCP |2 +1 A = CPV in B CPV in B: Time-dependent CPV Sanda Bigi Carter Dt made by H. Miyake mixing decay A=A: No DCPV sin-term only _ Mixing-induced CPV Direct CPV (A = -C)

  13. Discovery of b-quark p+N m+m- X e+e- collider U(1S) 1977 - BB 1978~ ARGUS (Doris, DESY) CLEO (CSER, Cornell) Not enough to observe CPV Lederman et al., Fermilab [PRL 39, 252 (1977)]

  14. Mt. Tsukuba PEP-II KEKB Belle ~1 km in diameter BaBar Asymmetric B Factories SLAC 9 GeV e- x 3.1 GeV e+ 8 GeV e- x 3.5 GeV e+ Head-on collision 11mrad crossing PEP-II (USA) KEKB (Japan) bg=0.425 bg=0.56

  15. Belle detector Ares RF cavity e+ source KEKB & PEP-II SCC RF(HER) ARES(LER)

  16. Peak Luminosity 1.65x1034 1.21x1034 >1fb-1/day >1 M BB _

  17. KEKB Linac

  18. KEKB Accelerator

  19. KEKB Accelerator ARES cavity Superconducting cavity

  20. Integrated Luminosity KEKB + PEP-II 1000/fb !! ~630 fb-1 KEKB for Belle Integrated Luminosity (fb-1) reached on July 13, 2006 PEP-II for BaBar ~ 1 Billion BB pairs ~400 fb-1

  21. Belle & BaBar collaborations Seoul National U. Shinshu U. Sungkyunkwan U. U. of Sydney Tata Institute Toho U. Tohoku U. Tohuku Gakuin U. U. of Tokyo Tokyo Inst. of Tech. Tokyo Metropolitan U. Tokyo U. of Agri. and Tech. Toyama Nat’l College U. of Tsukuba VPI Yonsei U. Nagoya U. Nara Women’s U. National Central U. National Taiwan U. National United U. Nihon Dental College Niigata U. Osaka U. Osaka City U. Panjab U. Peking U. U. of Pittsburgh Princeton U. Riken Saga U. USTC Aomori U. BINP Chiba U. Chonnam Nat’l U. U. of Cincinnati Ewha Womans U. Frankfurt U. Gyeongsang Nat’l U. U. of Hawaii Hiroshima Tech. IHEP, Beijing IHEP, Moscow IHEP, Vienna ITEP Kanagawa U. KEK Korea U. Krakow Inst. of Nucl. Phys. Kyoto U. Kyungpook Nat’l U. EPF Lausanne Jozef Stefan Inst. / U. of Ljubljana / U. of Maribor U. of Melbourne 13 countries, 55 institutes, ~400 collaborators

  22. Belle and BaBar Detectors m/KL detector (RPC+Fe) CsI(Tl) EM calorimeter SC solenoid (1.5T) TOF counter & Aerogel Cherenkov Si Vertex detector DIRC Drift Chamber (small cell)

  23. Detector Performance A big “digital camera” that we use to take ~108 beautiful pictures/year. Good Resolutions Momentum Energy (EM) Good PID e, m, p, K, p, KL Good Vertexing (decay point) O(1) ps

  24. _ _ _ _ c _ J/y _ d b b c t w B0 B0 _ B0 w w t s b d d K0 d * VudVub 2(a) * Vtd Vtb 3(g) 1(b) = - xcpsin2f1 sin(DmDt) +A cos (DmDt) A CP Mixing induced CPV Direct CPV Vcd Vcb * f1 Measurement V*cb V*td V*td A @ 0 xCP: CP eigenvalue First observed CPV in B (2001)

  25. Flavor-tag (B0 or B0 ?) Reconstruction J/(f,h’) e fCP e t=0 z Vertexing KS B0 B0 B0-tag B0-tag Dt z/cbg Time-dep CPV Measurement eeff ~30% sDt~140ps fit Extract CPV bg=0.425 (KEKB) 0.56 (PEP-II) same analysis method applied for all modes

  26. B0 J/y KS : Signals J/m+m ~10 MeV/c2 B0 J/ Ks(+ ) J/e+e ~11 MeV/c2 Ks+ ~4MeV/c2 Golden mode

  27. 535M BB B-meson Reconstruction Utilize special Kinematics at Y(4S) Energy difference: B0 J/y KS Beam-constrained mass: Nsig = 7482 Purity 97 % CP odd Mbc

  28. 535M BB m- m+ B0 J/y KL : Signals Nsig = 6512 Purity 59 % CP even KL pKL information is poor  lower purity KL direction + 2-body decay kinematics

  29. Flavor Tagging l+ u l- p+ ー d n ー n _ _ W+ _ W- ｃ ー ｓ ｂ K+ L B0 ｄ D* p- slow High-p (primary), low-p (secondary) leptons Strangeness (b  c  s) Fast p, slow p 2-stage Multi-dim. Likelihood based method (incl. correlations) Neural Network utilize all available info.

  30. D z D t = bg c ( ) ¡ Vertex Reconstruction Silicon Vertex detector s(zCP) ~ 75mm s(ztag) ~ 140mm IP constrained fit

  31. B0 tag (OF-SF)/(OF+SF) Mixing of D*ln Good tag region _ _ B0 tag B0 tag |Dt| (ps) Fit : extract sin2f1 -xCPsin2f1 B0 tag S = 0.65 A = 0.00 true R : detector resolution w : wrong tag fraction (misidentification of flavor)  (1-2w) quality of flavor tagging They are well determined by using control sample D*ln, D(*)p etc…

  32. 535M BB _ 347M BB New ! sin2f1: b g ccs _ _ (cc)K(*)0 BJ/yKs B0 tag _ B0 tag CP-even BJ/yKL CP-odd 0.710  0.034  0.019 sin2f1= 0.642  0.031  0.017 Preliminary [hep-ex/0607107] [hep-ex/0608039]

  33. 31M BB _ B0 tag sin2f1: History 1137 events B0 tag 2001 Asymmetry CPV Observed ! 0.674  0.026

  34. 535M BB B0 tag _ B0 tag sin2f1: History 14000 signals 2006 < 4% error ! 0.674  0.026

  35. Determination of UT Precise test of KM(CPV) and SM Bpp, rp, rr * Vtd Vtb * bul-n fB: Bln VudVub 2 Bp/r l n (a) Brg 3 1 (g) (b) B- DCPK- * - Vcd Vcb B0 (cc)K(*)0 B0 D(*)+p- bcl-n B0 D*+D(*)-(K) B  D(*)l n B experiments can provide all measurements !

  36. W _ _ d Vtb t p/r+ W u d g p/r+ u u Vub 0 d B p/r- p/r- d d u d d 0 d B * VudVub b b 2(a) * Vtd Vtb Vud Vtd   3(g) 1(b) Vcd Vcb * f2 measurement mixing Penguin Tree Isospin Analysis S¹x sinf2

  37. s u K+ W u c Vcb D0 s u u + d + d B B Vub D0 * VudVub b b 2(a) * c Vtd Vtb Vus Vcs   W K+ 3(g) 1(b) u u Vcd Vcb * f3 measurement Simple mixing CPV f3 (withBd ) + Tree Tree fCOM _ fCOM l3 l3 interference

  38. |Vcb | & |Vub | measurements Semileptonic B deacys - reasonably good theoretical understanding exclusive final states inclusive final states two ways: l- l- Vcb,Vub Vcb,Vub  W- W- l l b c(u) b c(u) |Vcb| < 2% |Vcb| ~ 7% SEVERAL THEORETICAL APPROACHES TO HANDLE HADRONIC EFFECTS

  39. Vtd t d b 0 d 0 d B B BBsfBs BBdfBd W W t b d Vtb Vtb Vtd   New ! Dmd mBs Dms mBd |Vtd | measurement >5s [hep-ex/0609040] Dmd= Cd BBdfBd2|Vtb*Vtd|2 Dmd = 0.507  0.005 ps-1 (1% error) Bs Dms = 17.77 0.10 0.07 ps-1 BBdfBd=223 35 MeV +0.047 -0.035 • = = 1.21 (~15% error) Lattice QCD (unquenched) (< 4% error) |Vtd| |Vts| |Vtd| ~15% error = x ( |Vtb| = 1) Al2 (~2% error) =

  40. UT angle & Side measurements a/f2 = [93 ] +11 - 9 g/f3 = [71 ] +22 -30 |Vub/Vcb| ~ 7% |Vtd /Vts| ~ 4%

  41. Summary of CKM/UT KM-phase = source for CPV ~ Established ! Precise Test of SM (& search for NP effect) ~ in progress (Need more Data)

  42. Search for New Physics In spite of Great Success of SM, there must be New Physics beyond it at High Energy scale CPV in B provide Powerful tool for Search NP ( New Phase ) Rare B decays excellent opportunities for NP search Loop diagram Penguins [bs(d) g, bs(d) l+l-] Key Decays involving t ( H) t Decays(Lepton Flavor Violation = NP) : B-factory = t-factory

  43. - b b SM: bs Penguin phase = (cc) K0 d d d d s s - X t s s s s New physics Search : b  sqq CPV f,h’.. f,h’.. _ B0 + KS KS * VtsVtb + New Physics with New Phase Sbs¹ Sbc , A can¹ 0 - “b  ccs: sin2f1” (SM reference)deviation

  44. (Spherical) (Jet-like) Event Shape Experimental Challenge We need 1) large number of BB pairs 2) additional background rejection B0g J/KS Tree much smaller BF B0gfKS Penguin Continuum Suppression using Event Shape likelihood

  45. 535M BB _ 347M BB New ! “Golden” mode:fK0 Preliminary fK0 unbinned fit SM “sin2f1” = +0.50  0.21  0.05 A = +0.07  0.15  0.06 “sin2f1” = +0.12  0.31  0.10 A = -0.18  0.20  0.10 [hep-ex/0608039] [hep-ex/0607112]

  46. 535M BB _ 384M BB New ! “Golden” mode:h’K0 1st observation b  s mode tCPV Preliminary h’K0 h’Ks h’KL unbinned fit SM 5.6s 5.5s “sin2f1” = +0.64  0.10  0.04 A = +0.01  0.07  0.05 “sin2f1” = +0.58  0.10  0.03 A = +0.16  0.07  0.03 [hep-ex/0608039] [hep-ex/0609052]

  47. Smaller than bgccs in all of 9 modes 2006: f1 with bgs Penguins Theory : tends to positive shifts Naïve average of all b g s modes sin2beff = 0.52 ± 0.05 2.6 s deviation Need more Data ! Preliminary

  48. Decays w/ “Missing E(>2n)” B  SM : B decay constant Lattice QCD BSM : sensitive to New Physics from H

  49. 449M BB _ Always > 2 neutrinos appear in B  t n decay n n Y(4S) B- B+ π+ B tn : Exp. Challenge Majority : 1 track +invisible N= 680k eff.= 0.29% purity = 57% Tag-side: Full reconstruction Charged B

  50. B tn : Candidate example Signature: Remove Tag-side 1 track + nothing No extra track EECL ~ 0

More Related