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CLEO 3 BELLE 1999 2001 BTEV ATLASATLAS ? 1999 2008 Intensa atividade experimental Além de dezenas de grupos experimentais pelo mundo …

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Apresentação em tema: "CLEO 3 BELLE 1999 2001 BTEV ATLASATLAS ? 1999 2008 Intensa atividade experimental Além de dezenas de grupos experimentais pelo mundo …"— Transcrição da apresentação:

1 CLEO 3 BELLE BTEV ATLASATLAS ? Intensa atividade experimental Além de dezenas de grupos experimentais pelo mundo …

2 Oscilações matéria – antimatéria decaimento Interações comuns ΔB=1 de troca de q (2/3) virtual t : dominant amplitude ΔB=2 V td ΔmdΔmd f B constante de decaimento B B Bag fator de sacola mésons neutros B 0 oscilam b d d b t t w-w- w-w- c e-e- b d w-w- d

3 Matriz de CKM = = fase de mistura Fase do decaimento fraco fase de mistura Os autoestados eletrofracos dos quarks são conectados aos estados de massa pela matriz de CKM: quatro parâmetros A, λ, ρ, η

4 No MP: Triângulos de unitariedade V td V tb +V cd V cb +V ud V ub = 0 (0,0) V ub V cb V td (, ) (1,0) V td V ud +V ts V us +V tb V ub = 0 V ub V td V ts medir todos os ângulos medir todos os lados MP: consistência!

5 violação de CP Três manifestações possíveis de violação de CP: Violação de CP direta (interferência entre duas amplitudes de decaimento) Violação de CP indireta (interferência entre duas amplitudes de mistura) Violação de CP na interferência entre decaimentos que oscilam (misturam) e entre decaimentos que não oscilam.

6 formalismo dependente do tempo para B d amplitude de decaimento para evolução temporal CP violation: interference between mixing and decay

7 formalismo dependente do tempo para B d Fábricas de b: Δt LHCb: t =0 B 0 J/ψK S =+sin(2β) MP: =0 =-sin(2β) B 0 J/ψK L

8 Medindo β Decaimentos do tipo B 0 J/ψK S e B 0 J/ψK L Bem entendidos na teoria: árvore and pinguin tem mesma fase Experimento relativamente simples

9 medindo β (D. Lange)

10 Fábricas de B : Belle, BaBar colisores assimétricos em Um ano: ~ 100 M pares Belle 132 fb -1 Março, 2003 BaBar 117 fb -1 Produção coerente

11 KEKB Luminosidade alcançada: 1.06 x cm -2 s -1

12 Detetor Babar

13 Sumário de sin2b em b ccs Já uma medida precisa: 7.5% Média mundial

14 rarer B decays Cabbibo supressed B 0 J/ 0 B K S Sensitive to new physics: smaller amplitudes, NP through interf. terms virtual particles (SUSY?) in penguin loops not theoretically clean smaller rates, higher back. Same CKM structure as B 0 J/ψK S expect S=sin2β to 5%

15 B 0 J/ 0 S = - sin2β if no penguin C = 0 if no penguin

16 Measuring β in b sss

17 Theoretical especulations sin(2β) = S ϕK = (2.7 σ) from the SM prediction; models from SUSY could explain this result! G.L. Kane et al., PRL Apr.2003 Grossman et al. hep-ph/

18 SM is alive and well! Confidence levels in the large (rhobar,etabar) plane obtained from the global fit. The constraint from the WA sin2beta (from psi Ks modes) is overlaid. Confidence levels in the large (rhobar,etabar) plane obtained from the global fit. The constraint from the WA sin2beta (from psi Ks modes) is included in the fit.

19 2007 More data close to theory limit from penguin pollution; Measurement of Δm S improve |V td /V cb | from near cancellation of B d and B s form factor; More data from Bh u lν and Bh c X together with improvement in theory will give some improvement in |V td /V cb | ;

20 Strategy: new physics! now yr LHCb B d J/ K S B d B s J/ B s D s K statistics!! Goal: Physics beyond the Standard model Measurements which provide a reference case for SM effects; Compare this to channels that might be affected by New Physics; Understand experimental and theoretical systematics to a level where we can draw conclusions.

21 for larger the B boost increses rapidly Hadronic b production B hadrons at Tevatron b quark pair produced preferentially at low highly correlated tagging low pt cuts

22 LHCb Experiment Acceptance : –15-300mrad (bending) –15-250mrad (non-bending) Particle ID –RICH detectors –Calorimeters –Muon Detectors Dedicated B physics Experiment at the LHC –pp collisions at 14TeV RICH1 Z ~ m RICH2 Z ~ m Calorimeters Z ~ m Muon System Z ~ m

23 One event!

24 for the decay channel B s D s + D s KKπ Tracking performance Average efficiency = 92 % Efficiency for p>5GeV >95% Ghost rate p T >0.5 GeV ~ 7%. Mass resolution (~13 MeV) (~13 MeV) Momentum resolution: p/p=0.38% Proper time resolution (42 fs) resolution (42 fs) = 27 tracks/event = 27 tracks/event

25 Hadron ID : Physics Performance No RICH With RICH n Signal Purity improved from 13% to 84% with RICH n Signal Efficiency 79% n RICH essential for hadronic decays n Example : B s K + K - n Sensitive to CKM angle

26 Muon Identification Muons selected by searching for muon stations hits compatible with reconstructed track extrapolations –Compare track slopes and distance of muon station hits from track extrapolation For P>3GeV/c eff = % misid = %

27 Measuring β gold-plated decay channel at B-factories for measuring the B d - B d mixing phase needed for extracting γ from B d ππ and B s K K in SM A dir =0, non-vanishing value (~0.01) could be a signal of Physics Beyond SM precision measurement important Inputs: 220 k/year signal 194 k/year back. A mix =sin(2β)=0.73 A dir = 0 ps A CP (t)

28 Rare B decays flavour changing neutral currents only at loop level very small BR ~ or smaller In the SM: Excellent probe of indirect effects of new physics! SM : BR ~ observation of the decay measurement of its BR CMS : 100 fb -1 (10 7 s at cm -2 s -1 ) ~ 26 signal events 6.4 events background LHCb : 2 fb -1 ~ 33 signal events ~ 10 events background σ M = 38 MeV + -,

29 A. Ali et al., Phys. Rev. D (2000) Rare B decays Forward-backward asymmetry can be calculated in SM and other models BTeV data compared to Burdman et al calculation

30 Conclusions LHCb and BTeV are second generation beauty CP violation experiments; They are well prepared to make crucial measurements in flavour physics with huge amount of statistics; Impressive number of different strategies for measurements of SM parameters and search of New Physics; CP violation is a cool research topic!! B factories established CP violation in the B sector and are making interesting measurements; Exciting times: understanding the origin of CP violation in the SM and beyond.


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