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Fisica del B e violazioni di CP ai futuri collider adronici

Fisica del B e violazioni di CP ai futuri collider adronici. Marta Calvi Universit à di Milano Bicocca e INFN. IFAE Torino 14-16 Aprile 2004. NP. NP. 2007.  2008. . B d J/ y K S. sin 2b. B s mixing. | V td / V ts |. f NR. | V ub / l V cs |.

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Fisica del B e violazioni di CP ai futuri collider adronici

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  1. Fisica del B e violazioni di CP ai futuri collider adronici Marta Calvi Università di Milano Bicocca e INFN IFAE Torino 14-16 Aprile 2004

  2. NP NP 2007  2008  BdJ/yKS sin 2b Bs mixing |Vtd/Vts| fNR |Vub/lVcs| |Vub/lVcs| r In 2007 several measurements on CKM will be available from B-Factorys and Tevatron But … New Physics could still be hidden in mixing or in penguins diagrams g measurement from BsDsK and BsJ/yf ?

  3. We need to overconstrain the Unitarity Triangles, search for signals of NP measuring several CP phases and look for NP in rare decays At hadronic colliders a huge bb cross section is available High statistics, access to Bd,u , Bs , b-baryon , Bc LHCLHCb dedicated exper.  2007 CMS ATLAS omni-purpose  2007 TEVATRON BTeV dedicated exper.  2009 CD0 approval in ‘03 CD1 expected end april Experimental challenges hadronic environment: b produced with wide range of momentum (no stringent constraints as at e+e- colliders), high multiplicity high rate of background events trigger is an issue

  4. BTeV LHC Tevatron CMS-ATLAS LHCb BTeV central det. forward det. forward det. s 14 TeV2 TeV stotal 100 mb 67 mb sinelelastic 80 mb50 mb sbb500mb100mb L(cm–2s-1) 2x1033(1034)2x1032 2 x1032 Nbb/year 1013 1012 2x1011 t bunch spacing25 ns(132) 396 ns W bunch crossing40 MHz (7.6) 2.5 MHz sz 5 cm 30 cm <Npp int./bco > ~2.30.4 (2) 6 qb qb bg h

  5. Bs Ds 144mm Bs vtx z resolution (mm) Without RICH Bd+- s=17 MeV K/p separation proper time resolution (fs) LHCb

  6. 40 MHz Level-0 1 MHz Level-1 40 kHz HLT 200 Hz L1 LHCb trigger high pT m, e, g, hadrons (~1-3GeV) Pile-up veto • High speed 2D VELO tracking Full 3D tracking and extrapolation to TT for high ip tracks • pT measured in 0.15 Tm field high impact parameter and high pT tracks software on complete event Signal Minimum bias

  7. LHCb trigger efficiency Efficiencies L0 output rate (MHz) efficiency L1 output rate (kHz)

  8. BsDsK s=138 m Primary-Secondary vertex resolution PbWO4 crystals s(E)/E<2% / E s=46 fs s(Mgg)=3.70.3 MeV Proper time resolution Br+p- BTeV RICHs C5F12 and C4F10 K-p and p-K separation >4 s for p=3-70 GeV s(MB)=29 MeV Bdpp s(MB)=17 MeV BsDsh

  9. Input (7.6) 2.5 MHz Vertex trigger + muon trigger Level 1 1/100 Level 2 Secondary vertex 1/10 Level 3 1/2 ~ 200 MB/s on tape BTeV Trigger Vertex trigger: based on 3D information from Pixel detector (Bmax=1.6T field) s<10mm Full reconstruction After a procedure of segment finding and vertex finding (3000 FPGA+DSP and micro-processors) measure impact parameter and count number of detached tracks

  10. Minimum-bias events Requiring 2 tracks detached by 6s retains 1% of beam crossings at <N>=2 Channel LVL1 eff(%) Channel LVL1 eff(%) B p+p- 63 Bo K+p- 63 Bs DsK 74 Bo J/y Ks 50 B- DoK- 70 Bs J/yK* 68 B- Ksp- 27 Bo K*g 40 ip/s BsD+sK- Recent re-evaluation at 396 ns <N>=6 ip4s Channel LVL1 eff(%) B p+p- 55 Bs DsK 70 B- DoK- 60 ip/s

  11. CMS Trigger start up in 2007: 4 DAQ slices  50kHz Level-1 designed to cover widest possible range of discovery Physics (Higgs, SuSy ...) B Physics selection triggered by single or di-muon triggers Muons are preferred to electrons because of lower trigger threshold Muons in HLT HLToutput fixed at100 Hz 30Hz allocated to 1m,2m (pT>19 GeV, pT>7 GeV) The content in b /c is too little (~5HZ): exploit online tracking to select exclusive b events Limited amount of CPU time (~50 msec in 2007):  reduce # tracks and # operation/track using regional reconstruction and conditional tracking Studies on some benchmark channels:Bsmm, BsJ/ , BsDspKKpp

  12. Bs m+m- Primary vertex reconstruction Only Pixel Detector CMS s=26mm Bs m+m-Bs mass resolution Secondary vertex reconstruction s=74 MeV s=46 MeV Full tracking HLT Bs m+m- Bs J/yf

  13. ATLAS Three level Trigger: 40 MHz Level-1 (20 kHz)  Level-2 (1-5 kHz)  Event Filter  (200 Hz) • B-physics ‘classical’ scenario: LVL1 muon with pT> 6 GeV, || < 2.4, LVL2 muon confirmation, ID full scan. • B-physics trigger revised for L=21033 cm-2s-1 and possibly reduced detector at start-up Alternatives: • single muon at LVL1 and additional requirements: a second muonJ/(+-),rare decays likeB  +-(X), etc. a Jet or EM RoI hadronic modes e.g. Bs Dsp ; electrons, e.g. J/ye+e- and reconstruct tracks at LVL2 and EF within RoI • flexible trigger strategy: start with a di-muon trigger for higher luminosities, add further triggers (hadronic final states, final states with electrons and muons) and/or lower the thresholds later in the beam-coast/for low-luminosity fills. Promising results, further studies ongoing.

  14. l K- B0 D B0 p- p+ b Bs s b s K+ u u Flavour Tag The knowledge of the b flavour at birth is essential for the majority of CP measurements •   tagging efficiency • D  (Nright -Nwrong)/(Nright+Nwrong) • effective efficiency  D2 Several methods: • Other B • Lepton • Kaon • Vertex charge /Jet charge • Signal B (same side) • Fragmentation kaon near Bs • Fragmentation pion near Bd • and pion from B** Bp

  15. Flavour tag LHCb: results are channel dependent (correlations with trigger and selection) Same side pion tag under developement BTeV partially optimistic results : No pattern recognition, m identification Only ggbb production process in MC, resulting in b and b back to back CMS / ATLAS

  16. Physics goals Reference measurements: sin(2) from B0J/Ks ms from BsDs CPV measurements: sin(2) and s from BsJ/, J/h(') BsDsK  from B0 and BsKK B0D0K*0 , B+D0K+ 2b+ fromB0D*  a=p-b- fromB0p, rp Rare decays: bs penguins

  17. Expected unmixed BsDs sample in one year of data taking (fast MC) 6 5 4 3 2 1 ms from BsDs LHCb 80k events/yr B/S=0.32Proper time res. 33 fs (core) 5 observation of Bs oscillation: 68 ps-1 / yr xs reach of BTeV 5 observation of Bs oscillation up to xs=80 ps-1 in 3.2 yr using Dsp

  18. ΦsandΓs from BsJ/Φ PS  VV decay: 3 contributing amplitudes 2 CP even, 1 CP odd  fit angular distribution of decay states as function of proper time. SM: Φs = -2 = -22 ~ -0.04 High sensitivity to NP contributions in Bsmixing LHCb 100k () events/yr B/S<0.3 proper time res. 38 fs (Φs) ~ 3.6O BTeV: 10k BsJ/h'events/yr 3k BsJ/h CP autostates: simpler analysis (Φs) ~ 2.8O CMS 40fb-1 300k events from HLT (Φs) ~ 2O Critical check:

  19. LHCb BsDsK BsDs  from BsDsK • Measure   sfrom time-dependentrates: BsDsK and BsDsK(+ CP-conjugates) • Use sfrom BsJ/ • Model independent Time dependent BsBs asymmetries LHCb 5.4 k events/ yr B/S<1.0 5 yrs of data, ms=20 ps-1 7.5k events / yr B/S: 0.14 BTeV (+Φs) ~ 80

  20. d d  from Band BsKK In both decays large b d(s) penguin contributions to bu: Measurement of time-dependent CP asymmetry for both decays • Method proposed by R. Fleischer: • use B and BsKK together • exploit U-spin flavour symmetry for P/T ratio described by d and  • Adir (B0 +-) = f1(d, , ) Amix(B0 +-) = f2(d, , , d) • Adir (BsK+K ) = f3(d’, ’, ) Amix(BsK+K ) = f4(d’,’, , s) • U-spin symmetry: d = d’and = ’ Φs (BsJ/) Φd (B0J/Ks) 4 measurements (CP asymmetries) and 3 unknown (, d and )  can solve for 

  21.  from Band BsKK “fake” solution LHCb events/yr B/SB 26k <0.7 BsKK 37k 0.31 BK+135k 0.16 BsK+ 5.3k <1.3 68% and 95% CL regions(input = 65º) B (95%CL) (A)~0.06 () = 46 deg BsKK (95%CL) BTeV events/ yr B/SB 15k 0.33 BK 62k 0.05 (A)~0.03 d vs 

  22. a from Br +p- bkgrnd signal Time dependent analysis of Dalitz plot to get a independently from penguin contributions BTeV mB (GeV) mB (GeV) Bor+p-5.4 k events/yr S/B = 4.1 Boropo 0.8 k events/yr S/B = 0.3 Fit with including resonant and non-resonant background with 1000 tagged events (2 years) minimum c2 non-resonant non-rp bkgrd resonant non-rp bkgrd da ~2o-4o in 2 years ainput=77.3o

  23. po reconstruction efficiency B+p- in LHCb New analysis of B+p- signal and background 2.5 increase of signal yield wrt TDR2003 (new variables, p id, use of multiple collision events…) Merged po Resolved po Dalitz plot BoK*(K+p-)po/ seems the most dangerous specific background. Reduced by a factor 6 to B/S ~6% using K/p separation from RICH Merged Mass resolution ~ 75 MeV/c2 10800 events/yr B/S<3 Resolved (conservative estimate based on … background events) Lower corner

  24. Sensitivity to New Physics in: B0K*0 +- +- invariant mass distribution +- forward-backward asymmetry SM: BR(B0K*0 +-) = (1.2  0.4) x 10-6 determination of |Vts| complementary to Dms/Dmd oscillation measurements AFB(s) LHCb Annual yield (SM): 4.4k B/S <2 (BR) ~ 3% (ACP) ~ 3% BTeV LHCb LHCb Annual yield (SM): 2.5k B/S=0.1 ATLAS Yield (30 fb-1) B/S Bd0 222 4.3 Bd0K* 1995 0.15 Bd0 411 0.34

  25. Event Yield (untagged) 1 year (107s) at L = 2x1032 cm-2 s-1

  26. Conclusion • New experiments at hadronic colliderswill offer soon an excellent opportunity to study many different B-meson decay modes with high statistics • determine precisely the CKM parameters through phase measurements • spot New Physics by overconstraining the Unitarity Triangles and measure rare decays • The goal will be reached thanks to: • excellent mass and decay-time resolution • excellent particle identification capability • The main challenge is the trigger An informal Italian Workshop on B Physics was held in Rome in Feb. 2004 to discuss experiences from running experiments and future ones. This was its first subject. More to come.

  27. Back up

  28. Branching Ratios

  29. √2 A3 √2 A3 A2 2 A2  A1 = A1 Variant of the Gronau-Wyler method proposed by I.Dunietz: A ( B DCPK* ) = A3 = 1/2 ( A(B D0K*) + A(B D0K* ) ) 1/2 ( A1 + |A2| ei (+))  from B DK* and B DK* together with CC decays  two triangle relations for amplitudes Measure 6 decay rates: 55 <  < 105 deg 20 <  < 20 deg () = 78 deg + cc sensitive to new phase in DCP =65o, =0

  30. B0K*0 and Bs g W b u,c,t s In SM: • loop-suppressed bs transitions • BR( B0 K*0) = (4.30.4) 10-5 • expected direct CP violation <1% for B0K*0 • expected CP violation in mixing ~0 for Bs  LHCb B0K*0 B0f  ATLAS B0 K*0 ~64MeV ~65MeV ~57MeV Events/yr B/S B0 K*0 (K+-) 35k <0.7 Bs  (K+K-) 9.3k <2.4 (ACP) ~ 0.01 (1 year) 10.5k evts 30 fb-1 B/S<3.3

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