B 2010 2 23 - PowerPoint PPT Presentation

B 崩壊の物理 飯嶋 徹 名古屋大学 2010 年 2 月 23 日 特定領域「フレーバー物理の新展開」研究会

B ファクトリーの 3 大物理成果 高輝度電子・陽電子衝突実験で切り開く物理 • B 崩壊における CP 対称性の破れの発見と 小林益川理論の検証 • b/ c / τ rare process における新物理探索 – B 稀崩壊： B  X s γ , K (*) ll, τν A02 計画研究 – D 中間子混合 居波 – τ LFV 高感度探索 ~O(10 -8 ) • 新しいハドロン共鳴の相次ぐ発見 森、有田 Super-KEKB/Belle II 実験へ 測定器開発

B ファクトリーの新たな可能性 We welcome your contribution Visit our home page ! http://www.hepl.phys.nagoya-u.ac.jp/public/new_hadron/index.html

Success of the B-factories 2008 Nobel Prize in Physics T. Maskawa M. Kobayashi Similar plot by the UT-fit group Still room for modifications by NP. Rare B decays are powerful tools ! 4

KEKB 加速器の成果 世界最高のルミノシティーを達成 クラブ衝突 L peak = 21.1 /nb/s L day =1479 /pb/day L total =955 /fb 2000 年 1 月 2009 年 6 月 2009 年 12 月までに >1ab -1 を達成 5

Luminosity at the B-factories ~950 fb -1 4S: 710fb -1 ~800M BB 5S: 86.fb -1 KEKB 3S: 3.3 fb -1 for Belle 2S: 6.7 fb -1 1S: 7.6 fb -1 Off peak: 90 fb -1 ~553 fb -1 4S: 433fb -1 3S: 30fb -1 2S: 14fb -1 ~ 470M BB Off peak: 54fb -1 PEP-II for BaBar Stopped in April 2008 6

− + B → K*ll 崩壊   +  ν γ , Z − −  − W + W W • FCNC 崩壊 b s s b t t • 極めてクリーンなプローブ   ∝ ℜ + * eff A C ( sC ( ) s r s C ( ) )   • 様々な測定量 FB 10 9 7 L - – q 2 分布 θ B – Forward-backward asymmetry K * – Isospin asymmetry etc. L + 657 M BB , 384M BB , submitted to PRL, arXiv: 0904.0770 PRD79, 031102(R) (2009) SM C 7 =-C 7 SM C 7 =-C 7 SM SM SM & C 7 =-C 7 C 9 C 10 =-(C 9 C 10 ) SM C 9 C 10 =-(C 9 C 10 ) SM CDF 三宅さんのトーク A FB exceeds SM ? 7

B - → l - ν −  b W − H − ν u • Within SM, proceed via W annihilation. → ν → µν → τ ν   Helicity suppression ( ) ( ) ( ) Br B e Br B Br B ~10 -7 ~10 -11 Determination of f B |V ub | = ± HPQCD, f 190 13 MeV − τν = ± × B 4 Br ( ) (1.20 0.25) 10 0902.1815v2 SM = ± ± × − 3 HFAG V (4.32 0.16 0.29) 10 ub ICHEP08 Sensitive also to NP (charged Higgs ) 8

Analysis for B → l ν S/N Hadronic tags Tagging side B tag → D (*) π / ρ etc. Reconstruct the recoil B to tag - B production π - B flavor/charge K - B momentum π e + Semileptonic tags ± B tag B sig  B tag → D (*) l ν etc. Υ (4S) D (*) v e - v Signal side: B sig → l ν −  - Detect charged track(s) - Missing energy (mass) due to ν ’s Inclusive tags - No extra activities in EM 4-vector sum of PID tracks calorimeter (E ECL(extra) ) (except for signal tracks) Eff 9

B  τν Candidate Event B + g D 0 π + K + π - π + π - B - g τ - ν e - νν 2009/03/19 Toru Iijima @ Hints09 10

Signal shape : Gauss + exponential Belle Results Background shape : second-order polynomial Signal +  Hadronic Tag (449M BB) background PRL 97, 251802 (2006) Br( ) =[1.79 +0.56 (stat) +0.46 (syst)] 10 -4 τν × -0.49 -0.51 N =24.1 +7.6 (stat) +5.5 (syst) S -6.6 -6.3 in all EECL region. Background 3.5 σ (incl. syst.) B  τν  Semileptonic Tag (657M BB) Signal BELLE-CONF-0840, arXiv:0809.3834 Br( ) =[1.65 +0.38 (stat) +0.35 (syst)] 10 -4 τν × -0.37 -0.37 N =154 +36 (stat) +21 (syst) S -35 -22 3.8 σ (incl. syst.) 2009/03/19 Toru Iijima @ Hints09 11

Constraint on Charged Higgs Naïve world average [ ] Br( ) =[1.73 0.35] 10 Br ( ) = 1.20 ±0.25 10 -4 -4 τν ± × τν × SM Based on fB from HPQCD and |V ub | from Effect of Charged Higgs HFAG (BLNP, ICHEP08) W. Hou, Phys. Rev. D48, 2342 (1993) Constraint on charged Higgs = × Br Br r , SM H 2   β 2 2 m tan 1 Type-II 2HDM =  B  r 1- + ε β H 2   m 1 tan H 0 v SUSY Loop correction β = u tan ε 0 =0 for Type-II 2HDM v d 95%CL exclude 12

However….  Can we rely on lattice for f B ?  Can we rely on |V ub | ? 2009/03/19 Toru Iijima @ Hints09 13

If we use CKM fit… Br( ) =(0.937 +0.096 ) 10 -4 τν × -0.015 fit Br( ) =(0.786 ) 10 +0.179 -4 τν × fit -0.083 τν is not included in the fit HFAG summer08 (1.51 ± 0.33)x10 -4 CKM2008 (1.73 ± 0.35)x10 -4 2009/03/19 Toru Iijima @ Hints09 14

β B → D τ ν m tan b c b B  D τ ν is also sensitive to H + , and β H + / W + m τ tan complementary to B  τν . τ + ν τ •Relatively large Br ~0.8% •Different theory systematics: – free from V ub and f B uncertainties. – depends on the B  D form factors, → τν Br B ( D ) = R D ( ) → ν  Br B ( D )  Three-body decay permits the study of decay distributions which discriminate between W + and H + exchange. U. Nierste, S. Trine, S.Westhoff PRD78, 015006 (2008).  Universality between H-b-c, (D τν ), H-b-u ( τν ), H-b-t (LHC) can be tested. arXiv:0906.1652 (hep-ph/) 15 A. Cornell, A. Deandrea, N. Gaur, H. Itoh, M. Klasen, Y. Okada

B → D τ ν w/ by Belle First observation of B  D* τ ν w/ inclusive tag PRL99, 191807 (2007), • 657M BB + → D τ ν + 0 B • Hadronic tags. • Extract signals in (MM 2 , E ECL ) distribution. • Simultaneous extraction of D τν /D* τν . − + → D τ ν 0 B R(%) Ns Signif. D 0 τ ν +26.3 +18.9 +11.0 3.8(4.4) 70.2 98.6 -18.0 -9.1 -25.0 D + τ ν +21.6 +6.3 +7.7 2.6(2.8) 47.6 17.2 -6.9 -19.3 -5.4 D* 0 τ ν +10.6 +6.2 +22.2 3.9(5.2) 46.8 99.8 -22.3 -10.2 -7.2 D *+ τ ν +14.0 +5.8 +7.2 4.7(5.9) 25.0 48.1 -6.3 -12.3 -4.1 D τν signal D* τν cross talk 16

B → D τν : BaBar+Belle My Naïve Average → τν • Belle R(D) =[60 14(stat) 8(syst)]% ± ± Br B ( D ) = R D ( ) → ν • BaBar  R(D) =[41.6 11.7(stat) (syst)]% ± ± Br B ( D ) 5.2 • Belle+BaBar R(D) =[49 10]% ± Constraint on Charged Higgs Type-II 2HDM form factors 95%CL excluded → τν = τ 2 2 Br B ( D ) G V f F ( , F , g ) by B  τν F B cb V S S 2 m = β 95%CL excluded 2 B g tan (Type-II 2HDM) S 2 m by B  D τν H H. Itoh, S. Komine and Y. Okada, PTP 114, 179 (2005), hep-ph/0503124. D l ν form factor reported by BaBar; arXiv: 0807.4978, 0809.0828 17

Sensitivity to charged Higgs 5 σ discovery sensitivity tan β Charged Higgs boson Atlas Belle II, 5 ab -1 Belle II, 50 ab -1 excluded currently (Br(B →τν )) @ 95.5% 5 σ discovery, Belle II, 5 ab -1 5 σ discovery, Belle II, 50 ab -1 m H+ [GeV] Belle II Br(B →τν )) sensitive to H + at large m H+ and tan β at low tan β B → X s γ constraints the parameters Belle II reach @ L can be parametrized: tan β ≥ 5 · √ (0.5 ab -1 / L ) ·[1·10 -4 GeV -2 · (m - 90 GeV) 2 + 12.2] B.Golob

B ファクトリーのアップグレード 目標ルミノシティー = 8 × 10 35 cm -2 s -1 • RF の増強 より高いビーム電流 • 衝突点の改良 より小さいビームサイズ Super-KEKB L =8x10 34 cm -2 s -1 ∫ Ldt =50ab -1 I LER/ Ｈ ER =2.96/1.70A β y * = 0.22mm ∫ Ldt =10ab -1 Three year shutdown to: 4 install new beam pipe Present KEKB 4 increase RF L =2x10 34 cm -2 s -1 4 modify IR + Belle upgrade I LER/ Ｈ ER =1.62/0.95A β y * = 5.9mm ∫ Ldt = 1ab - 1 2010 2015 2020 Physics with O(10 10 ) B, τ , charm 19

Physics Reach at Super-KEKB/Belle Belle’06 5ab -1 50ab -1 CP asymmetry in B → KKK , φ K and η ’ K (~0.5ab -1 ) 0.3 ■ ● ★ ∆ S( φ K 0 ) 0.22 0.073 0.029 ∆ S( η ’K 0 ) 0.11 0.038 0.020 (3 σ discovery lim.) Deviation from SM 0.1 ∆ S(K S K S K S ) 0.33 0.105 0.037 A FB ∆ S(K S π 0 γ ) 0.32 0.10 0.03 Present 50ab -1 exp. limits Br(X s γ ) 13% 0.03 A CP (X s γ ) 0.058 0.01 0.005 5ab -1 50ab -1 C 9 [A FB (K*ll)] --- 11% 4% 0.01 Forward-Backward C 10 [A FB (K*ll)] --- 13% 4% 1 10 100 Asymmetry in B  K*ll Br(B + → K + νν ) 33ab -1 for 5 σ discovery Integ. luminosity (ab -1 ) <9Br(SM) Upper limits Br(B + → τν ) 3.5 σ 10% 3% Br(B + → µν ) 4.3ab -1 for 5 σ discovery <2.4Br(SM) q 2 (GeV 2 /c 2 ) Br(B + → D τν ) --- 7.9% 2.5% Br( τ → µγ ) <45 <30 <8 Br( τ → µη ) <65 <20 <4 X10 -9 Br( τ → 3 µ ) <209 <10 <1 ∆ sin2 φ 1 0.026 0.016 0.012 ∆Φ 2 ( ρπ ) 68 ° ー 95 ° 3 ° 1 ° ∆Φ 3 ( Dalitz) 20 ° 7 ° 2.5 ° CKM at 50ab - Integ. Lum. （ ab -1 ） ∆ V ub (incl.) 7.3% 6.6% 6.1% Reach of B factories 20 Upgraded KEKB

Colliding bunches 7GeV New Superconducting / e- 2.1 A permanent final focusing 4GeV quads near the IP Nano-Beam e+ 3.7 A SuperKEKB Replace long TRISTAN dipoles with shorter ones (HER). Add / modify rf systems for higher currents. Low emittance positrons to Redesign the HER arcs to inject squeeze the emitance. Low emittance gun Low emittance electrons to New positron target / capture inject section x40 Gain in Luminosity 21 TiN coated beam pipe with antechambers