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January, 2005Kowalewski --- Perugia lectures1 Lectures on B Physics Bob Kowalewski University of Victoria Currently at La Sapienza and the Laboratorio.

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Presentation on theme: "January, 2005Kowalewski --- Perugia lectures1 Lectures on B Physics Bob Kowalewski University of Victoria Currently at La Sapienza and the Laboratorio."— Presentation transcript:

1 January, 2005Kowalewski --- Perugia lectures1 Lectures on B Physics Bob Kowalewski University of Victoria Currently at La Sapienza and the Laboratorio Nazionale di Frascati

2 January, 2005 Kowalewski --- Perugia lectures 2 Overview of the lectures Lecture 1: History, facilities, B production and decay, CKM matrix Lecture 2: Semileptonic and radiative B decays Lecture 3: Oscillations and CP violation Lecture 4: CP violation

3 January, 2005 Kowalewski --- Perugia lectures 3 Lecture 1 History of B physics: 1977 – 2004 Significant facilities, past and present B meson production and decay CKM matrix

4 January, 2005 Kowalewski --- Perugia lectures 4 Historical context 1974 was an exciting year for particle physics, with the discovery of the (2 nd generation) charm quark (J/ ψ ) and the (3 rd generation) τ lepton The search for a 3 rd generation of quarks was motivated by symmetry with the lepton sector as well as by the insight of Kobayashi and Maskawa (in 1973) that a 3x3 quark mixing matrix has an irreducible imaginary parameter that can lead to CP violation

5 January, 2005 Kowalewski --- Perugia lectures 5 Upsilon experiment at FNAL 400 GeV proton beam incident on target Look for muon pairs; measure invariant mass

6 January, 2005 Kowalewski --- Perugia lectures 6 Initial results

7 January, 2005 Kowalewski --- Perugia lectures 7 Discovery of the b quark 1977: Lederman et al. discover Υ resonances in μ + μ - mass spectrum  Υ (1S), Υ (2S), Υ (3S) Interpreted as bound states of a new quark, b, the first quark of the 3 rd generation: Electromagnetic decay seen (μ + μ - ) Decay width is narrow Lederman receives Nobel Prize in 1988 for this work.

8 January, 2005 Kowalewski --- Perugia lectures 8 Later data States seen are the first 3 radial excitations of the vector bb state Υ (1S), Υ (2S), Υ (3S) Observed width is experimental resol n Quantum numbers J PC =1 -- b mass ~ 4.6 GeV

9 January, 2005 Kowalewski --- Perugia lectures 9 Limitations of technique Only muon pairs are recorded! Limited mass resolution Not well suited for fine-grained study No clear signature for separating b-flavored particles (i.e. bq - B mesons) from background Need e + e - experiment to examine in detail

10 January, 2005 Kowalewski --- Perugia lectures 10 First e + e - facilities At the time of Υ discovery, Cornell was building CESR, a 16 GeV center-of-mass e + e - collider CESR was subsequently redesigned to run in the Υ energy range: GeV The CLEO and CUSB detectors started collecting data in 1979

11 January, 2005 Kowalewski --- Perugia lectures 11 e + e - takes over 3 narrow Υ States seen immediately; observed width = beam energy spread Broader Υ (4S) resonance seen at GeV; above BB threshold 1S 2S 3S m B B 0 and B + discovered by CLEO (1982) B * mesons at CUSB (1985) ARGUS detector (DORIS-II) starts at DESY (1982)

12 January, 2005 Kowalewski --- Perugia lectures 12 CESR and CLEO

13 January, 2005 Kowalewski --- Perugia lectures 13 DORIS-II and ARGUS

14 January, 2005 Kowalewski --- Perugia lectures 14 Initial findings B mesons have significant semileptonic branching fractions: BF(B  X ℓ ν ) ~ 10% B mesons are spin 0 B + and B 0 have m B = GeV (Δm<1 MeV) B decay dominated by b  c transition (|V cb | >> |V ub |) B mesons have long (~1.5 ps) lifetimes (|V cb |<<1) FCNC decays not observed (constrain topless models)

15 January, 2005 Kowalewski --- Perugia lectures 15 Early discoveries – B 0 mixing B 0 and B 0 mix to produce mass eigenstates; Δm~0.5 ps -1. First seen by ARGUS (1987) At Υ (4S), ~1 B 0 in 6 decays as B 0 Confirmed by CLEO in 1988 Initial B flavor cannot be determined; need 1 B to decay first

16 January, 2005 Kowalewski --- Perugia lectures 16 The flavor oscillation is now mapped out over ~1.5 full periods Δm = (0.502±0.006) ps -1 Fast-forward 14 years… mixed unmixed dileptons 20.7 fb Belle dileptons 29.4 fb

17 January, 2005 Kowalewski --- Perugia lectures 17 Early discoveries – b  u ℓ ν b  u transitions observed by CLEO (1989). Signature is an excess of leptons with momenta above the kinematically allowed range for b  c decays. b  u rate ~ 1/50 b  c rate q bcbc

18 January, 2005 Kowalewski --- Perugia lectures years later… Data (continuum sub) MC for BB background S/B ~ 1/25 at 2.0 GeV!

19 January, 2005 Kowalewski --- Perugia lectures 19 Radiative Penguin decays 1993 – exclusive decay B  K * γ seen in CLEO 1995 – inclusive b  s γ process measured (much harder!) Rate probes new physics BaBar B 0  K *0 γ

20 January, 2005 Kowalewski --- Perugia lectures 20 Contributions from higher energy e + e - machines Full range of b-flavored hadron states produced The PEP (SLAC) and PETRA (DESY) experiments (√s~30 GeV) made early measurements of the average B lifetime LEP experiments and SLD made numerous contributions in Z decays: Precise B lifetimes; lifetime differences Discovery of B s and Λ b Discovery of P-wave B mesons (B ** )

21 January, 2005 Kowalewski --- Perugia lectures 21 P-wave B ** Discovery Resonant structure appears in the unlike-sign B + π ± distribution Mass resolution insufficient to separate states Excess in B + π - combinations B+ π+ combinations agree with MC B + π ± invariant mass

22 January, 2005 Kowalewski --- Perugia lectures 22 Hadron colliders for b physics Fermilab Tevatron experiments CDF and D0 have made important contributions to B s decays b-hadron lifetimes Future hadron facilities (LHC-b, B-TeV and, possibly, ATLAS and CMS at LHC) may make a number of important measurements B s oscillations and CP violation Leptonic and some radiative B decays

23 January, 2005 Kowalewski --- Perugia lectures 23 The B factory era CESR had an impressive history…but new challenges require new facilities B factories >100 fb-1 / year

24 January, 2005 Kowalewski --- Perugia lectures 24 B factory design goals Major physics motivation: CP violation in B decays Requires asymmetric beam energies (Odone) Requires high luminosity: KEK-B proposed at KEK; luminosity target 1 ×10 34 cm -2 s -1 PEP-2 proposed at SLAC; luminosity target 0.3×10 34 cm -2 s -1 Peak luminosity of cm -2 s -1 gives integrated luminosity per year of ~ 150 fb -1 or ~2×10 8 Υ (4S) decays

25 January, 2005 Kowalewski --- Perugia lectures 25 PEP-II and KEK-B Jonathan Dorfan Pier Oddone

26 January, 2005 Kowalewski --- Perugia lectures 26 B factories: PEP-II and KEK-B Both B factories are running well: Belle BaBar Belle L max (10 33 /cm 2 /s) best day (pb -1 ) total (fb -1 )

27 January, 2005 Kowalewski --- Perugia lectures 27 B factory detectors DIRC DCH IFR SVT CsI (Tl) e - (9 GeV) e + (3.1 GeV) Belle BaBar Belle and BaBar are similar in performance; some different choices made for Cherenkov, silicon detectors Slightly different boost, interaction region geometry (crossing angle)

28 January, 2005 Kowalewski --- Perugia lectures 28 The collaborations By any pre-LHC standard, this is big science; BaBar has ~ 600 members, Belle ~ 300 (not all pictured in either case!) Pep2 / BaBar KEKB / Belle

29 January, 2005 Kowalewski --- Perugia lectures 29 B meson production Production in e + e - at Υ (4S) {Z} cross-section ~1.1nb, purity (bb / Σ i q i q i ) ~ 0.3{7nb, 0.22} simple initial state: BB in p-wave, decay products overlap {b quark hadronizes to B+: B 0 : B s : b-baryon ~ 0.4, 0.4, 0.1, 0.1; b and b jets separated} “easy” to trigger, apply kinematic constraints Production at hadron machines (gluon fusion) cross-sections much higher (×10 4 ) All b hadrons are produced triggering harder, purity (b / Σ i q i ) ~ (few/10 3 )

30 January, 2005 Kowalewski --- Perugia lectures 30 Y(4S) experiments e + e - → Y(4S) → B + B - or B 0 B 0 ; roughly 50% each B nearly at rest (βγ ~ 0.06) in 4S frame; no flight info B energy = ½ c.m. energy; valuable constraint, since σ E ~50 MeV for reconstruction, ~5 MeV for e + e - beams on peak off peak (q=u,d,s,c) 2m B qq BB

31 January, 2005 Kowalewski --- Perugia lectures 31 Asymmetric B factories Boost CM along beam (z) axis Separation of B and B decay ~ βγcτ B ~ 250 μm Boost imposes asymmetry in detector design Required luminosity is large since CP eigenstates have small product BF to states with clean signatures; e.g. BF(B 0  J/ ψ( ℓ + ℓ - ) K S ) < Angular coverage is a compromise between luminosity (quadrupole magnets close to IR) and detector acceptance

32 January, 2005 Kowalewski --- Perugia lectures 32 B decay basics B mesons are the lightest b-flavored particles; they must decay weakly (Δb=1) The 0 th order picture is of a free b quark weak decay Putting back the light quark we get the spectator (or external W emission) decays Other decay diagrams are suppressed either by color matching or some power of 1/m B.

33 January, 2005 Kowalewski --- Perugia lectures 33 Charged-current Lagrangian in SM: Since m b << M W, the effective 4-fermion interaction is CKM suppressed (|V cb |<<1) → long lifetime ~ 1.5ps b quark decay c e ν e b ×3 for color

34 January, 2005 Kowalewski --- Perugia lectures 34 b quarks and B mesons… The b quark decay is simple B meson decay is not… V cb

35 January, 2005 Kowalewski --- Perugia lectures 35 Spectator decays Semileptonic ~ 26% Hadronic ~ 73% single hadronic current; ~reliable theory Heavy Quark Expansion B  F form factors Theoretical predictions tend to have large uncertainties. Factorization (W decay products do not mix with other quarks) partly works

36 January, 2005 Kowalewski --- Perugia lectures 36 Leptonic decays Leptonic < 10 -4, 7,11 τ, μ, e b u Suppressed by helicity (like π  e ν ) measures f B ×|V ub | b d l +, W+W+ W–W– l –,l’ –, B0B0 Helicity suppressed; FCNC In SM: B(B 0   +  – ) ~ 8× B(B 0  ) ~ zero B+B+

37 January, 2005 Kowalewski --- Perugia lectures 37 Non-spectator decays Colour-suppressed; Includes all b  cc q’q EW penguins; 2 nd order weak ℓℓ ℓℓ ℓℓ ℓℓ ℓ, ν W exchange gluonic penguins; 2 nd order weak Large m t enhances these loop diagrams b q s,d q q

38 January, 2005 Kowalewski --- Perugia lectures 38 Box diagrams 2 nd order Δb=2 transition takes B 0 →B 0 making decay eigenstates distinct from flavour eigenstates Large m t makes up for Weak suppression B 0 → B 0 : (B 0 →B 0 ) / B 0 = 0.18

39 January, 2005 Kowalewski --- Perugia lectures 39 CKM matrix Kobayashi and Maskawa noted that a 3 rd generation results in an irreducible phase in mixing matrix: Observed smallness of off-diagonal terms suggests a parameterization in powers of sinθ C 3 x 3 unitary matrix. Only phase differences are physical, → 3 real angles and 1 imaginary phase

40 January, 2005 Kowalewski --- Perugia lectures 40 Wolfenstein++ parameterization Buras, Lautenbacher, Ostermaier, PRD 50 (1994) shown here to O(λ 5 ) where λ=sinθ 12 =0.22 V us, V cb and V ub have simple forms by definition Free parameters A, ρ and η are order unity Unitarity triangle of interest is V ud V * ub +V cd V * cb +V td V * tb =0 Note that |V ts /V cb | = 1 + O(λ 2 ) uctuct d s b all terms O(λ 3 )

41 January, 2005 Kowalewski --- Perugia lectures 41 A Unitarity Triangle   RtRt RuRu 

42 January, 2005 Kowalewski --- Perugia lectures 42 B decays – a window on the quark sector The only 3 rd generation quark we can study in detail Investigate flavour-changing processes, oscillations CKM matrix Cabibbo angle B d B d and B s B s oscillations B lifetime, decay =1 CP Asymmetries (phase)

43 January, 2005 Kowalewski --- Perugia lectures 43 Surveying the unitarity triangle The sides of the triangle are measured in b→uℓν and b→cℓν transitions (R u ) and in B d 0 -B d 0 and B s 0 -B s 0 oscillations (R t ) CP asymmetries measure the angles V ub, V cb and V td measure the sides GET A BETTER PICTURE RuRu RtRt   

44 January, 2005 Kowalewski --- Perugia lectures 44 End of Lecture 1

45 January, 2005 Kowalewski --- Perugia lectures 45 Lecture 2 – Semileptonic and Radiative B Decays B meson decays – role of QCD Heavy Quark symmetry Exclusive semileptonic decays Inclusive semileptonic decays Radiative decays veloce p.s. – se parlo troppo veloce non esitate a dirmelo

46 January, 2005 Kowalewski --- Perugia lectures 46 Surveying the unitarity triangle The sides of the triangle are measured in b→uℓν and b→cℓν transitions (R u ) and in B d 0 -B d 0 and B s 0 -B s 0 oscillations (R t ) CP asymmetries measure the angles Today we’ll talk about the rings GET A BETTER PICTURE RuRu RtRt   

47 January, 2005 Kowalewski --- Perugia lectures 47 Recall: The b quark decay is simple B meson decay is less so… V cb

48 January, 2005 Kowalewski --- Perugia lectures 48 B hadron decay – parton model Bound b quark is virtual and has some “Fermi momentum” b quark then has p b = p F and E b = M B - p F, so m b =√( M B 2 - 2M B p F ) Parton model usually assigns p F from a Gaussian with r.m.s. of ~ 0.5 GeV p F ~ 0.5 GeV, corresponds to m b ~ 4.8 GeV gives a reasonable description of some inclusive spectra (e.g. p e ) Ad-hoc model; hard to assign uncertainties to predictions

49 January, 2005 Kowalewski --- Perugia lectures 49 Beyond parton model… Parton model had some successes, but did not provide quantitative estimates of theoretical uncertainties. How does QCD modify the weak decay of the b quark? QCD becomes non-perturbative at Λ QCD ~ 0.5 GeV but is perturbative for m b : α s (m b )~0.22 Modern approaches, based on heavy quark symmetry: use the operator product expansion (OPE) to separate short- and long-distance physics Leads to effective field theories, e.g. HQE, SCET… Used to calculate form factors in lattice QCD X h ν e e B

50 January, 2005 Kowalewski --- Perugia lectures 50 Heavy Quarks in QCD Heavy Quarks have m Q >> Λ QCD (or Compton wavelength λ Q << 1/Λ QCD ) Soft gluons (p ~ Λ QCD ) cannot probe the quantum numbers of a heavy quark → Heavy Quark Symmetry γ binding e - and N in atoms can’t probe nuclear mass, spin… isotopes have similar chemistry! b

51 January, 2005 Kowalewski --- Perugia lectures 51 Heavy Quark Symmetry For m Q →∞ the light degrees of freedom (spectator, gluons…) decouple from those of the heavy quark; the light degrees of freedom are invariant under changes to the heavy quark mass, spin and flavour S Q and J ℓ are separately conserved: S Q +J ℓ = J; J ℓ = L+S ℓ The heavy quark (atomic nucleus) acts as a static source of color (electric) charge. Color magnetic effects are relativistic and thus suppressed by 1/m Q

52 January, 2005 Kowalewski --- Perugia lectures 52 Heavy Quark symmetry group The heavy quark spin-flavour symmetry forms an SU(2N h ) symmetry group, where N h is the number of heavy quark flavours. In the SM, t and b are heavy quarks; c is borderline. No hadrons form with t quarks (they decay too rapidly) so in practice only b and c hadrons are of interest in applying heavy quark symmetry This symmetry group forms the basis of an effective theory of QCD: Heavy Quark Effective Theory

53 January, 2005 Kowalewski --- Perugia lectures 53 Heavy Quark Effective Theory The heavy quark is almost on-shell: p Q =m Q v+k, where k is the residual momentum, k μ << m Q The velocity v is ~ same for heavy quark and hadron The QCD Lagrangian for a heavy quark can be rewritten to emphasize HQ symmetry: H give rise to fluctuations O(2m b ); h correspond to light d.o.f.

54 January, 2005 Kowalewski --- Perugia lectures 54 HQET Lagrangian The first term is all that remains for m Q →∞; it is clearly invariant under HQ spin-flavour symmetry The terms proportional to 1/m Q are the kinetic energy operator O K for the residual motion of the heavy quark, and the interaction of the heavy quark spin with the color- magnetic field, (operator O G ) The associated matrix elements are non-perturbative; however, they are related to measurable quantities

55 January, 2005 Kowalewski --- Perugia lectures 55 Non-perturbative parameters The kinetic energy term is parameterized by λ 1 = /2m B The spin dependent term is parameterized by λ 2 = - /6m B The mass of a heavy meson is given by The parameter Λ arises from the light quark degrees of freedom and is defined by Λ = lim m→∞ (m H – m Q )

56 January, 2005 Kowalewski --- Perugia lectures 56 Phenomenological consequences The spin-flavour symmetry relates b and c hadrons: SU(3) Flavour breaking: m(B s ) - m(B d ) = Λ s – Λ d + O(1/m b ); 90±3 MeV m(D s ) - m(D d ) = Λ s – Λ d + O(1/m c ); 99±1 MeV Vector-pseudoscalar splittings: (→ λ 2 ~ 0.12 GeV) m 2 (B * ) - m 2 (B) = 4λ 2 +O(1/m b ); 0.49 GeV 2 m 2 (D * ) - m 2 (D) = 4λ 2 +O(1/m c ); 0.55 GeV 2 baryon-meson splittings: m(Λ b ) - m(B) - 3λ 2 /2m B + O(1/m b 2 ); 312±6 MeV m(Λ c ) - m(D) - 3λ 2 /2m D + O(1/m c 2 ); 320±1 MeV

57 January, 2005 Kowalewski --- Perugia lectures 57 Exclusive semileptonic decays (heavy  heavy) HQET simplifies the description of B  X c eν decays and allows precise determination of |V cb | Consider the (“zero recoil”) limit in which v c =v b (i.e. when the leptons take away all the kinetic energy) If SU(2N h ) were exact, the light QCD degrees of freedom wouldn’t know that anything happened For m Q →∞ the form factor can depend only on w=v b ·v c (the relativistic boost relating b and c frames) This universal function is known as the Isgur-Wise function, and satisfies ξ(w = 1) = 1. D * ν e e B

58 January, 2005 Kowalewski --- Perugia lectures 58 Determination of |V cb | The zero-recoil point in B  D (*) eν is suppressed by phase space; the rate vanishes at w=1. One must extrapolate from w>1 to w=1. includes radiative and HQ symmetry-breaking corrections, and Luke’s theorem

59 January, 2005 Kowalewski --- Perugia lectures 59 Current status of |V cb | from B→D * eν Measurements of the rate at w=1 are experimentally challenging due to limited statistics: dΓ/dw(w=1) = 0 softness of transition π from D * →D extrapolation to w=1 Current status (Heavy Flavor Averaging Group): 5% uncertainty

60 January, 2005 Kowalewski --- Perugia lectures 60 Tests of HQET Predicted relations between form factors can be used to test HQET and explore symmetry-breaking terms The accuracy of tests at present is close to testing the lowest order symmetry-breaking corrections – e.g. the ratio of form factors  /  for B→Deν / B→D * eν is

61 January, 2005 Kowalewski --- Perugia lectures 61 Lattice QCD for B decay In principle, we can do everything on the lattice In practice, there are problems: Unquenched calculations (i.e. those involving quark loops) only recently feasible b is heavy; lattice spacing a would have to be <1/m b for proper treatment, and this is not yet possible  use HQET ideas here too Extrapolation to real world (a  0 and m q  0) introduces uncertainties Important for exclusive B  light form factors and B decay constant

62 January, 2005 Kowalewski --- Perugia lectures 62 Exclusive charmless semileptonic decays HQET is not helpful in analyzing B  X u eν decays in order to extract |V ub | The decays B 0 →π + ℓ - ν and B→ρℓ - ν have been observed (BF ~ 2×10 -4 ) Lattice calculations of form factor in B→πℓν decay give uncertainties on |V ub | in the 15-20% range for large q 2 =m B 2 +m π 2 +2m B E π Other decays tend to be more challenging π ν e e B

63 January, 2005 Kowalewski --- Perugia lectures 63 Inclusive semileptonic decays Inclusive decays  sum over all exclusive channels Complementary to exclusive semileptonic decays for both experiment (only lepton(s) measured), and theory (sum over final states  can ignore hadronization) Starting point is optical theorem which relates Γ(B  X) to imaginary part of forward scattering amplitude Applies to both b  u and b  c semileptonic decays

64 January, 2005 Kowalewski --- Perugia lectures 64 Operator Product Expansion The heavy particle fields can be integrated out of the full Lagrangian to yield an effective theory with the same low-energy behaviour (e.g. V-A theory) The effective action is non-local; locality is restored in an expansion (OPE) of local operators of increasing dimension ( ~1/[M heavy ] n ) The coefficients are modified by perturbative corrections to the short-distance physics An arbitrary scale μ separates short- and long-distance effects; the physics cannot depend on it

65 January, 2005 Kowalewski --- Perugia lectures 65 OPE in B decays The scale μ separating short/long distance doesn’t matter … except in finite order calculations  typically use Λ QCD << μ ~ m b << M W ; α S (m b ) ~ 0.22 Wilson coefficients C i (μ) contain weak decay and perturbative QCD processes The matrix elements in the sum are non-perturbative Renormalization group allows summation of terms involving large logs (ln M W /μ) → improved C i (μ)

66 January, 2005 Kowalewski --- Perugia lectures 66 Inclusive Decay Rates The inclusive decay widths of B hadrons into partially-specified final states (e.g. semileptonic) can be calculated using an OPE based on: 1.HQET - the effects on the b quark of being bound to light d.o.f. can be accounted for in a 1/m b expansion involving familiar non-perturbative matrix elements 2.Parton-hadron duality – the hypothesis that decay widths summed over many final states are insensitive to the properties of individual hadrons and can be calculated at the parton level.

67 January, 2005 Kowalewski --- Perugia lectures 67 Parton-Hadron Duality One distinguishes two cases: Global duality – the integration over a large range of invariant hadronic mass provides the smearing, as in e + e - →hadrons and semileptonic HQ decays Local duality – a stronger assumption; the sum over multiple decay channels provides the smearing (e.g. b→sγ vs. B→X s γ). No good near kinematic boundary. Global duality is on firmer ground, both theoretically and experimentally

68 January, 2005 Kowalewski --- Perugia lectures 68 Heavy Quark Expansion The decay rate into all states with quantum numbers f is Expanding this in α S and 1/m b leads to where λ 1 and λ 2 are the HQET kinetic energy and chromomagnetic matrix elements. Note the absence of any 1/m b term! free quark

69 January, 2005 Kowalewski --- Perugia lectures 69 Inclusive semileptonic decays The HQE can be used for both b→u and b→c decays The dependence on m b 5 must be dealt with; in fact, an ambiguity of order Λ QCD exists in defining m b. Care must be taken to correct all quantities to the same order in α S in the same scheme) The non-perturbative parameters λ 1 and λ 2 must be measured: λ 2 ~0.12 GeV from B * -B splitting; λ 1 from b→sγ, moments in semileptonic decays, … X ν e e B

70 January, 2005 Kowalewski --- Perugia lectures 70 b-hadron lifetimes (1/Γ) Need these to go from BF to partial Γ HFAG average values (as of Summer, 2004): SpeciesLifetime B0B0 1534±13 fs B+B+ 1653±14 fs B + /B ±0.015 BsBs 1469±59 fs ΛbΛb 1232±72 fs BcBc 450±120 fs

71 January, 2005 Kowalewski --- Perugia lectures 71 μ π 2 ~ λ 1 μ G 2 ~ λ 2

72 January, 2005 Kowalewski --- Perugia lectures 72 Spectral moments OPE calculation is done at the parton level Applying the OPE calculations to real hadrons (duality) requires summing over a “large enough” phase space Low-order spectral moments (integrals over distributions) should be insensitive to duality A complete set of calculations is available for b  cℓ ν mass and lepton energy moments Measurements always need cut on lepton energy

73 January, 2005 Kowalewski --- Perugia lectures 73 Cross-checks of fit results E e moments calculated up to α s 2 β 0 ; M X moments to α s (higher orders small compared with exp error) Separate fits to E e and M x moments agree well Values for μ G 2 and ρ LS 3 are consistent with independent measurements based on m B* -m B and HQ sum rules. Overall power of E e and M X moments is comparable

74 January, 2005 Kowalewski --- Perugia lectures 74 OPE preliminary fit results |V cb | measured to 2%!

75 January, 2005 Kowalewski --- Perugia lectures 75 Relating |V ub | to Γ(B  X u ℓ ν ) Recall m b 5 dependence of total s.l. width The m b appearing in the HQE is the pole mass; it is infrared sensitive (it changes at different orders in PT) m b defined in an appropriate renormalization scheme (there are several) results in faster convergence of OPE Fairly precise relations can then be obtained for |V ub |: 1 Hoang, Ligeti and Manohar, hep-ph/ % error Moving on to |V ub |…

76 January, 2005 Kowalewski --- Perugia lectures 76 Data (eff. corrected) MC Data (continuum sub) MC for BB background Determination of |V ub | The same method (Γ SL ) can be used to extract |V ub |. Additional theoretical uncertainties arise due to the restrictive phase space cuts needed to reject the dominant B→X c eν decays Traditional method uses endpoint (>2.3 GeV) of lepton momentum spectrum; recent progress pushes this to 2.0 GeV

77 January, 2005 Kowalewski --- Perugia lectures 77 Newer methods for determining |V ub | 2.mass m x recoiling against ℓν (acceptance ~70%, but requires full reconstruction of 1 B meson) b→c allowed mX2mX2 1.invariant mass q 2 of ℓν pair (acceptance ~20%, requires neutrino reconstruction) B 0 →X u ℓ - ν B→X u ℓ - ν

78 January, 2005 Kowalewski --- Perugia lectures 78 Recent data on inclusive b  uℓ ν The better acceptance and signal-to-background comes at the cost of statistics and complexity (one needs to measure more things) B A B AR

79 January, 2005 Kowalewski --- Perugia lectures 79 Shape function The Shape function, i.e. the light- cone b quark momentum distribution Needed where OPE breaks down Some estimators (e.g., q 2 ) are insensitive to it S h max (GeV 2 ) accept reject

80 January, 2005 Kowalewski --- Perugia lectures 80 m X vs. q 2 Inclusive |V ub | results |V ub | is measured to ~ ±9% E ℓ endpoint m X fit E ℓ vs. q 2 Results have been re-adjusted by the Heavy Flavor Averaging Group

81 January, 2005 Kowalewski --- Perugia lectures 81 Measuring non-perturbative parameters and testing HQE m b and λ 1 can be measured from E γ distribution in b→sγ moments (m X, s X, E ℓ, E W +p W ) in semileptonic decays Comparing values extracted from different measurements tests HQE This is currently an area of significant activity λ1λ1 m b /2→Λ

82 January, 2005 Kowalewski --- Perugia lectures 82 Hadronic B decays More complicated than semileptonic or leptonic decays due to larger number of colored objects Many of the interesting decays are charmless → HQET not applicable QCD factorization and other approaches can be used, but jury is still out on how well they agree with data No more will be said in these lectures

83 January, 2005 Kowalewski --- Perugia lectures 83 Radiative Penguin Decays and New Physics SM leading order = one EW loop V ts, V td dependent FCNCs probe a high virtual energy scale comparable to high-energy colliders Radiative FCNCs have precise SM predictions: BF(b → s  ) TH = 3.57 ± 0.30 x (SM NLO) BF(b → s  ) EXP = 3.54 ± 0.30 x (HFAG) Decay rate agreement highly constrains new physics at the electroweak scale! Further tests presented here: Exclusive b → s  decay rates b → s  CP asymmetries b → d  penguins Multiple new BF(b → s  ) measurements coming soon from BaBar Radiative penguin decays: b → s  and b → d  FCNC transitions Berryhil, ICHEP2004

84 January, 2005 Kowalewski --- Perugia lectures 84 b→s(d)γ B→K * γ and b→sγ (inclusive) both observed by CLEO in mid-90s; first EW penguins in B decay BR consistent with SM; limits H +, SUSY: BF(b→sγ) = (3.5 ±0.3 )×10 -4 (expt) = (3.4 ±0.6 )×10 -4 (theory) BF(B→K * γ) = (40.1 ±2.0 )×10 -6 (expt) non-strange b  dγ modes not yet observed; but B→ργ and B  ωγ nearly so. E γ spectrum is used to probe shape function

85 January, 2005 Kowalewski --- Perugia lectures 85 |V td |/|V ts | from B  ρ γ / B  K * γ Combined BF(  ) ≡ BF(  +  ) = 2(  + /  0 ) BF(  0  ) = 2(  + /  0 ) BF(   ) BF = (0.6 ± 0.3 ± 0.1) x10 -6 BF < 1.2 x % CL  95% C.L. BaBar allowed region (inside the blue arc) With/without theory error

86 January, 2005 Kowalewski --- Perugia lectures 86 Radiative FCNC decays

87 January, 2005 Kowalewski --- Perugia lectures 87 Sensitivity to new physics

88 January, 2005 Kowalewski --- Perugia lectures 88 b→sνν Cleanest rare B decay; sensitive to all generations (important, since b→sτ + τ - can’t be measured) BF quoted are sum over all ν species SM predictions: BF(B → X s νν) < 6.4×10 -4 at 90% c.l. (ALEPH) BF(B + →K + νν) < 5.2×10 -5 at 90% c.l. (BaBar submitted to PRL ) ℓℓ ℓℓ ℓℓ ℓℓ ℓ, ν

89 January, 2005 Kowalewski --- Perugia lectures 89 Lecture 2: summary Semileptonic decays give crucial information on the CKM elements |V cb | and |V ub | Heavy Quark Symmetry is the tool used to quantitatively understand these decays Progress in this area involves a vibrant interplay between theory (QCD effective field theories) and experiment; progress is being made in both Radiative decays offer opportunities for seeing new physics, since they are highly suppressed in the SM

90 January, 2005 Kowalewski --- Perugia lectures 90 Lecture 3: Oscillations and CP violation B 0 B 0 oscillations – theory and experiment CP violation in SM – basic mechanisms CP violation in B decays Measurement of unitarity triangle angle β Lecture 4 – CP violation Direct CP violation Determining α Prospects for γ Summary

91 January, 2005 Kowalewski --- Perugia lectures 91 B 0 -B 0 oscillations B mesons are produced in strong or EM interactions in states of definite flavour 2 nd order Δb=2 transition takes B 0 →B 0 making mass eigenstates distinct from flavour eigenstates Neutral B mesons form 2-state system: Mass eigenstates diagonalize effective Hamiltonian

92 January, 2005 Kowalewski --- Perugia lectures 92 Effective Hamiltonian for mixing Two Hermitian matrices M and Γ describe physics Quark masses, QCD+EM Δb=2 intermediate state off-shell, on-shell Weak decay M 11 =M 22 (CPT) Γ 11 = Γ 22 Diagonalize to get heavy (H) and light (L) eigenstates: m H, m L

93 January, 2005 Kowalewski --- Perugia lectures 93 The time evolution of the B 0 B 0 system satisfies The dispersive part of the matrix element corresponds to virtual intermediate states and contributes to Δm The absorptive part corresponds to real intermediate (flavour-neutral) states and gives rise to ΔΓ Δm, ΔΓ →1 →0 →1 →0 <<

94 January, 2005 Kowalewski --- Perugia lectures 94 B d oscillations For B 0 (bd), ΔΓ/Γ<<1: only O(~1%) of possible decays are to flavour-neutral states (ccdd or uudd); dominant decays are to cudd or cℓνd Consequently, most decay modes correlate with the b quark flavour at decay time. Contrast with K 0 system The large top quark mass breaks the GIM cancellation of this FCNC and enhances rate Δm; large τ B allows oscillations to compete with decay

95 January, 2005 Kowalewski --- Perugia lectures mixed unmixed dileptons 20.7 fb -1 Evidence for B d oscillations The fraction of opposite- sign dileptons vs. time (does not go from 0 to 1 due to mis-tagging) Y(4S) has J PC =1 - - so BB are in a P-wave. B 1 and B 2 are orthogonal linear combinations of B eigenstates Δm = (0.502±0.006) ps Belle dileptons 29.4 fb

96 January, 2005 Kowalewski --- Perugia lectures 96 SM expectation for B d oscillations The box diagram for Δb=2 transitions contains both perturbative and non-perturbative elements Operator Product Expansion (OPE) calculation gives Uncertainty in B B F B 2 dominates (~30%) Hope for improvements using Lattice QCD pert. QCD From universal f n of (m t /m W ) 2

97 January, 2005 Kowalewski --- Perugia lectures 97 Experimental status of B s oscillations In the B S system the CKM-favoured decay b→ccs leads to flavour-neutral (ccss) states ΔΓ/Γ may be up to ~15% (HFAG: ΔΓ/Γ < 0.54 at 95% c.l.) Still have ΔΓ<< Δm Δm d /Δm s ~ (|V td |/|V ts |) 2 ~ 30 (corrections are O(15%)) HFAG: Δm s > 14.5 ps -1 at 95% c.l. (LEP/SLD/CDF) Fast oscillations are hard to study (one complete oscillation every γ·50μm).

98 January, 2005 Kowalewski --- Perugia lectures 98 Unitarity triangle constraints from non-CP violating quantities These measurements alone strongly favour a non-zero area for the triangle; this implies CP violation in SM

99 January, 2005 Kowalewski --- Perugia lectures 99 CP violation CP violation is one of the requirements for producing a matter-dominated universe (Sakharov) Why isn’t C violation alone enough (C|Y> = |Y>)?... Chirality: if Y L behaves identically to Y R then CP is a good symmetry. In this case the violation of C does not lead to a matter–antimatter asymmetry. CP violation first observed in K 0 L decays to the (CP even) ππ final state (1964)

100 January, 2005 Kowalewski --- Perugia lectures 100 Physicist’s Rorschack

101 January, 2005 Kowalewski --- Perugia lectures 101 Mechanism for CP violation in SM: Kobayashi and Maskawa mixing matrix with 1 irreducible phase CP violation is proportional to the area of any unitarity triangle, each of which has area |J|/2, where J = Jarlskog invariant = c 12 c 23 c 2 13 s 12 s 23 s 13 sinδ ~ A 2 λ 6 η J max is (6√3) -1 ~ 0.1; observed value is ~4·10 -5 ; this is why we say “CP violation in SM is small” Since it depends on a phase, the only observable effects come from interference between amplitudes CP violation in SM

102 January, 2005 Kowalewski --- Perugia lectures 102 CP violation in flavour mixing This is the CP violation first observed in nature, namely the decay of K L to ππ, which comes about because of a small CP-even component to the K L wavefunction Caused by interference between ΔΓ and Δm in mixing; very small in B system because ΔΓ<<Δm This type of CP violation is responsible for the small asymmetry in the rates for K L →π + e - ν e and K L →π - e + ν e Non-perturbative QCD prevents precise predictions for this type of CP violation

103 January, 2005 Kowalewski --- Perugia lectures 103 CP Violation in Mixing HFAG: |q/p| = ± off-shell on-shell CP-invariant phase arbitrary phase

104 January, 2005 Kowalewski --- Perugia lectures 104 Direct CP violation CP violation in decay amplitude 2 amplitudes A 1 and A 2 Strong phase difference Weak phase difference For neutral modes, direct CP violation competes with other types of CP violation Non-perturbative QCD prevents precise predictions for this type of CP violation; most interesting modes are those with A CP ~0 in SM no CPV partial decay rate asymmetry From Gautier Hamel de Monchenault

105 January, 2005 Kowalewski --- Perugia lectures 105 CP violation in the interference between mixing and decay CP eigenvalue amplitude ratio mixing Time-integrated asymmetry vanishes!

106 January, 2005 Kowalewski --- Perugia lectures 106 Calculating if just one direct decay amplitude to f CP Piece from mixing (q/p) Piece from decay No dependence on δ! → pure phase ~0

107 January, 2005 Kowalewski --- Perugia lectures 107 Calculating  for specific final states B 0 mixing decay K 0 mixing assuming only tree-level decay

108 January, 2005 Kowalewski --- Perugia lectures 108 B 0 decays to CP eigenstates that are dominated by a single decay amplitude allow a clean prediction for the CP asymmetry: where θ CKM is related to the angles of the unitarity triangle (e.g. θ CKM = β for B→J/ψ K S ) Mother Nature has been kind!

109 January, 2005 Kowalewski --- Perugia lectures 109 From the recent CKM2005 workshop: Mother Nature has been very kind!

110 January, 2005 Kowalewski --- Perugia lectures 110 Relation to unitarity triangle    (1,0)  (0,0) (  ) Semileptonic B  X u e  B 0 d oscillations B 0 s oscillations (bd)→uudd (bd)→ccsd, ccdd, ccss, sssd (bd)→cusd (bd)→cudd

111 January, 2005 Kowalewski --- Perugia lectures 111 Measuring CP violation in B d decays CP violation in B d decays can be studied at asymmetric e + e - colliders (B factories) with √s=m Y(4S) Time integrated CP asymmetry vanishes – measurement of Δt uses boost of CM along beam line and precise position measurements of charged tracks Reconstruction of CP eigenstates requires good momentum and energy resolution and acceptance Determination of flavour at decay time requires the non-CP “tag B” to be partially reconstructed

112 January, 2005 Kowalewski --- Perugia lectures 112 Overview of CP asymmetry measurement at B factories B-Flavor Tagging Exclusive B Meson Reconstruction (flavor eigenstates) lifetime, mixing analyses (CP eigenstates) CP analysis

113 January, 2005 Kowalewski --- Perugia lectures 113 Relation of mixing, CP asymmetries Use the large statistics B flav data sample to determine the mis-tagging probabilities and the parameters of the time-resolution function Time-dependence of CP-violating asymmetry in B 0 CP  J/ ψ K 0 S Time-dependence of B 0 -B 0 mixing dilution due to mis-tagging

114 January, 2005 Kowalewski --- Perugia lectures 114 Paying homage to Father Time measure Δz = lifetime convoluted with vertex resolution; derive Δt z of fully reconstructed B is easy to measure; z of other B biased due to D flight length. Same effects arise for CP and flavour eigenstates Unmixed Mixed

115 January, 2005 Kowalewski --- Perugia lectures 115 Impact of mistagging,  t resolution No mistagging and perfect  t Nomix Mix tt tt D=1-2w=0.5  t res: 99% at 1 ps; 1% at 8 ps w=Prob. for wrong tag tt tt Raw asymmetry

116 January, 2005 Kowalewski --- Perugia lectures 116 Flavour determination of tag B Use charge of decay products Lepton Kaon Soft pion Use topological variables e.g., to distinguish between primary, cascade lepton Use hierarchical tagging based on physics content Four tagging categories: Lepton, Kaon, NN; ε ~ 70% Effective Tagging Efficiency

117 January, 2005 Kowalewski --- Perugia lectures 117 B reconstruction B→J/ψK 0, J/ψ→ℓ + ℓ - is very clean; can be used at hadron machines as well At e + e - b factories kinematic constraints allow use of K L too! Belle BaBar

118 January, 2005 Kowalewski --- Perugia lectures 118 Results for β BaBar and Belle both see significant CP violation: sin2 β = 0.725±0.033±0.017 C = 0.031±0.025±0.015 Also | λ f |=0.950±0.031±0.013 (recall λ f =(q/p)*(A f /A f ) ) BaBar Belle syserr ↓ as ∫Ldt ↑

119 January, 2005 Kowalewski --- Perugia lectures 119 Asymmetries in b  sss: a bit too strange? Penguin decays of the type b  sss are expected to have the same asymmetry as b  ccs Uncertainties ~5-10% depending on mode Measurements of B 0  φK 0 s, B 0  η ’ K 0 s, B 0  K + K - K 0 s and others give smaller values: sin2 β = 0.41 ± 0.07 (recall b  ccs gives 0.725±0.037) The two results are 3.8σ apart! More data may reveal a significant departure from SM

120 January, 2005 Kowalewski --- Perugia lectures 120 bsssbsss Status at ICHEP’04 φK 0 is pure Penguin

121 January, 2005 Kowalewski --- Perugia lectures 121 sin2  and..... and.... New phases from SUSY? In SM interference between B mixing, K mixing and Penguin b  sss or b  sdd gives the same e  as in tree process b  ccs. However loops can also be sensitive to New Physics!

122 January, 2005 Kowalewski --- Perugia lectures 122 Lecture 3 summary B 0 oscillations have ΔΓ<<Δm, are CP conserving B 0 s can have sizable ΔΓ/Γ; B 0 d have ΔΓ<<Γ CP violation in SM due to phase  interference 3 kinds of CP violation: in mixing, in decay (direct) and in the interference between mixing and decay 3 rd form allows clean measurements of weak phases CP asymmetry measurements can be done with precision; many experimental handles available from more prevalent flavor eigenstates b  sss transitions show intriguing difference from SM

123 January, 2005 Kowalewski --- Perugia lectures 123 Lecture 4 – CP violation Direct CP violation Determining α Prospects for γ Summary Lecture 3: Oscillations and CP violation B 0 B 0 oscillations – theory and experiment CP violation in SM – basic mechanisms CP violation in B decays Measurement of unitarity triangle angle β

124 January, 2005 Kowalewski --- Perugia lectures 124 CKM matrix Kobayashi and Maskawa noted that a 3 rd generation results in an irreducible phase in mixing matrix: Observed smallness of off-diagonal terms suggests a parameterization in powers of sinθ C 3 x 3 unitary matrix. Only phase differences are physical, → 3 real angles and 1 imaginary phase

125 January, 2005 Kowalewski --- Perugia lectures 125 Wolfenstein++ parameterization Buras, Lautenbacher, Ostermaier, PRD 50 (1994) shown here to O(λ 5 ) where λ=sinθ 12 =0.22 V us, V cb and V ub have simple forms by definition Free parameters A, ρ and η are order unity Unitarity triangle of interest is V ud V * ub +V cd V * cb +V td V * tb =0 Note that |V ts /V cb | = 1 + O(λ 2 ) uctuct d s b all terms O(λ 3 )

126 January, 2005 Kowalewski --- Perugia lectures 126 A Unitarity Triangle   RtRt RuRu 

127 January, 2005 Kowalewski --- Perugia lectures 127 Direct CP violation CP violation in decay amplitude 2 amplitudes A 1 and A 2 Strong phase difference Weak phase difference For neutral modes, direct CP violation competes with other types of CP violation Non-perturbative QCD prevents precise predictions for this type of CP violation; most interesting modes are those with A CP ~0 in SM no CPV partial decay rate asymmetry From Gautier Hamel de Monchenault

128 January, 2005 Kowalewski --- Perugia lectures 128 CP violation in the interference between mixing and decay CP eigenvalue amplitude ratio mixing Time-integrated asymmetry vanishes!

129 January, 2005 Kowalewski --- Perugia lectures 129 Direct CP violation Recall that direct CP violation arises in the interference of two competing decay amplitudes to the same final state It can affect any particle decay (not just neutral mesons), and does not vanish when integrated over decay time It was first observed in K 0 L decay in 1999, after decades of effort It has now been seen in B 0 decays (2004)

130 January, 2005 Kowalewski --- Perugia lectures 130 Direct CP violation in B 0  K + π - Exciting discovery in 2004: first observation of direct CP violation in B 0  K + π - Discrepancy in B +  K + π 0 s K- K - s

131 January, 2005 Kowalewski --- Perugia lectures 131 Angle α – not as simple as β The quark level transition b→uud gives access to sin(2α). In this case, however, tree and Penguin amplitudes can be comparable; more complicated. Decay modes: B 0 →ππ, ρπ, ρρ… In practice, the coefficients of the time dependent CP asymmetry, S ππ and C ππ (=-A ππ ), are measured Additional measurements are needed to separately determine the tree and penguin amplitudes; these involve all B→ππ charge combinations or B→ρπ or ρρ with an analysis of the Dalitz plot.

132 January, 2005 Kowalewski --- Perugia lectures 132 The angle α Interference of suppressed b  u “tree” decay with mixing but: “penguin” is sizeable! B 0 mixingB 0 decay: tree With no penguinsWith large penguins and |P/T| ~ 0.3 B 0 decay: penguin Coefficients of time-dependent CP Asymmetry

133 January, 2005 Kowalewski --- Perugia lectures 133 Isospin analysis:  eff   Gronau-London isospin analysis: J=0 two-pion state has no I=1, so B  can be described in terms of two I-spin amplitudes A +0 has no gluonic penguin  base is common to B + and B - Grossman-Quinn bound: Useful if  0  0 is small; doesn’t require  0  0 to be tagged since uses sum 2

134 January, 2005 Kowalewski --- Perugia lectures 134 Result for B  0   6.0  BABAR CONF-04/035 Grossman-Quinn bound:

135 January, 2005 Kowalewski --- Perugia lectures 135 Results on B  ππ B A B AR Comparison Caution averaging! S 2 +C 2 ≤1 physically

136 January, 2005 Kowalewski --- Perugia lectures 136 Sin2α from B 0  ρρ Extraction of  similar to , but with advantage of smaller Penguin pollution: B A B AR

137 January, 2005 Kowalewski --- Perugia lectures 137 More on B  ρρ PRL 91 (2003) Compare with 35 o for  B A B AR BABAR CONF-04/037

138 January, 2005 Kowalewski --- Perugia lectures 138 Summary of constraints on  Mirror solutions disfavored BABAR & Belle combined

139 January, 2005 Kowalewski --- Perugia lectures 139 CKM constraints and sin2  and  measurements  CKM fit to indirect constraints overlaid with sin2β and  measurements Constraints on  starting to have an impact

140 January, 2005 Kowalewski --- Perugia lectures 140 Approaches to γ The quark-level decay b  cus gives rise to direct CP asymmetries involving γ The quantity sin(2β + γ) can be measured in time- dependent decays involving b  cud

141 January, 2005 Kowalewski --- Perugia lectures 141 sin(2β+ γ ) from B 0  D (*) - π + decays Same final state reached by B 0, B 0 in different diagrams

142 January, 2005 Kowalewski --- Perugia lectures 142 Status of sin(2β+ γ ) Fit determines coefficients of time-dependent terms; further input still needed to get sin(2β+ γ )

143 January, 2005 Kowalewski --- Perugia lectures 143 Idea – use D 0 CP eigenstates f CP : K + K -, K S π, π + π -

144 January, 2005 Kowalewski --- Perugia lectures 144 Idea – use DCS D 0 decays

145 January, 2005 Kowalewski --- Perugia lectures 145 Experimental status of GLW/ADS Signals seen and CP asymmetries measured for GLW method; however, more input (r B and δ) needed to determine γ Decay modes of interest for ADS method not yet measured; however, smallness of R ADS can be used to set upper limit on r B

146 January, 2005 Kowalewski --- Perugia lectures 146 D 0 CP eigenstates, multibody

147 January, 2005 Kowalewski --- Perugia lectures 147 Dalitz amplitude fits – wow!

148 January, 2005 Kowalewski --- Perugia lectures 148 Promising, but needs more data

149 January, 2005 Kowalewski --- Perugia lectures 149 CP violation in B s decays The B s system can be used to study CP violation Presence of spectator s quark → different set of angles However B s production is suppressed, and ∆m s is very large (fast oscil.) Rapid oscillation term (Δm s ~30Δm d ) makes time resolved experiments difficult Width difference ΔΓ may be exploited instead Dedicated B experiments at hadron facilities (like LHC-B) will be needed to do this

150 January, 2005 Kowalewski --- Perugia lectures 150 Current status in ρ-η space Measurements are consistent with SM CP asymmetries from B factories now dominate the determination of η Improved precision needed on |V ub | and other angles (α,γ) B s oscillations too!

151 January, 2005 Kowalewski --- Perugia lectures 151 Radiative Penguin Decays and New Physics SM leading order = one EW loop V ts, V td dependent FCNCs probe a high virtual energy scale comparable to high-energy colliders Radiative FCNCs have precise SM predictions: BF(b → s  ) TH = 3.57 ± 0.30 x (SM NLO) BF(b → s  ) EXP = 3.54 ± 0.30 x (HFAG) Decay rate agreement highly constrains new physics at the electroweak scale! Further tests presented here: Exclusive b → s  decay rates b → s  CP asymmetries b → d  penguins Multiple new BF(b → s  ) measurements coming soon from BaBar Radiative penguin decays: b → s  and b → d  FCNC transitions Berryhil, ICHEP2004

152 January, 2005 Kowalewski --- Perugia lectures 152 b→s(d)γ B→K * γ and b→sγ (inclusive) both observed by CLEO in mid-90s; first EW penguins in B decay BR consistent with SM; limits H +, SUSY: BF(b→sγ) = (3.5 ±0.3 )×10 -4 (expt) = (3.4 ±0.6 )×10 -4 (theory) BF(B→K * γ) = (40.1 ±2.0 )×10 -6 (expt) non-strange b  dγ modes not yet observed; but B→ργ and B  ωγ nearly so. E γ spectrum is used to probe shape function

153 January, 2005 Kowalewski --- Perugia lectures 153 |V td |/|V ts | from B  ρ γ / B  K * γ Combined BF(  ) ≡ BF(  +  ) = 2(  + /  0 ) BF(  0  ) = 2(  + /  0 ) BF(   ) BF = (0.6 ± 0.3 ± 0.1) x10 -6 BF < 1.2 x % CL  95% C.L. BaBar allowed region (inside the blue arc) With/without theory error

154 January, 2005 Kowalewski --- Perugia lectures 154 Radiative FCNC decays

155 January, 2005 Kowalewski --- Perugia lectures 155 Sensitivity to new physics

156 January, 2005 Kowalewski --- Perugia lectures 156 b→sνν Cleanest rare B decay; sensitive to all generations (important, since b→sτ + τ - can’t be measured) BF quoted are sum over all ν species SM predictions: BF(B → X s νν) < 6.4×10 -4 at 90% c.l. (ALEPH) BF(B + →K + νν) < 5.2×10 -5 at 90% c.l. (BaBar submitted to PRL ) ℓℓ ℓℓ ℓℓ ℓℓ ℓ, ν

157 January, 2005 Kowalewski --- Perugia lectures 157 History… Courtesy of the UTfit people (http://utfit.roma1.infn.it/)http://utfit.roma1.infn.it/ Progress due to improvements in theory, measuring sides, and (last) measuring CP violation in B Non-trivial test of CKM!

158 January, 2005 Kowalewski --- Perugia lectures 158 B Physics – broad and deep CP violation in B decays is large and will be observed in many modes Precision studies of B decays and oscillations provide the dominant source of information on 3 of the 4 CKM parameters Rare B decays offer a good window on new physics due to large m t and |V tb | B hadrons are a laboratory for studying QCD at large and small scales. A large range of measurements can be made to test our calculations. Modern techniques allow a quantitative estimate of theoretical errors

159 January, 2005 Kowalewski --- Perugia lectures 159 A glimpse of things to come? B physics and neutrino experiments have produced the most significant discoveries since the LEP/SLC program The same two fields will probe deeper into flavour mixing and CP violation CKM physics is becoming high precision physics New experiments at hadron machines will probe B s oscillations, CP and rare decays

160 January, 2005 Kowalewski --- Perugia lectures 160 Grazie… a Maurizio per l’invito e l’ospitalita’ a tutti voi per l’ascolto


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