Beauty and Charm: An Assault on the Standard Model Steven Blusk Syracuse Colloquium

1. Beauty and Charm: An Assault on the Standard ModelSteven BluskSyracuse Colloquium Outline Introduction to SM & Flavor Physics, Phenomenology CLEO-c and Charm, why now? Leptonic decays The new B frontier: LHCb Summary

2. Fundamental Questions • How did the Universe evolve? • What laws of physics were present in the early Universe to produce the Universe we see today? • Multi-pronged attack • Cosmology • Particle Physics • Terrestrial based • Astrophysical

3. Cosmological Breakthroughs A lot of excitement over our new view of the Universe WMAP Data: Cosmic Microwave Background Type 1 Supernovae • Dark Matter candidates? • Dark Energy? • Inflation? New Physics

4. Another “cosmological” mystery • Why is the Universe composed almost entirely of matter? • Matter = Antimatter, just after Big Bang(natural, simplest assumption) • Today, matter dominated Universe. • How can this asymmetry be explained? • Do the interactions (forces) in nature favor matter over antimatter? AND • Is it large enough to account for the preponderance of matter over antimatter. • If “NO”, what new interactions are manifest at high energy scales? • Particle physics may be able to answer these and many other fundamental questions.

5. The(sub)Standard Model

6. u c t +2/3 s d b -1/3 t- m- -1 nm nt 0 Peeling back the layers of matter e - ne Each of these 6 quarks and 6 leptons have corresponding antiparticles

7. Standard Model Forces + … HiggsBoson H0 Energy-Momentum exchange Interactions == Particle Exchange EM Force g Strong Force g WeakForce W± Z0 There MUST be a strongerforce present within the confines of the nucleus. Why do atomsstay together? Why does the nucleus stay together, despite the repulsive EM forcebetween protons ? • Introduce a new (Higgs) field into SM. • Unifies EM & Weak (Electroweak) • SM particles acquire mass via their interactions with the Higgs field. Introducing mass terms into the SM Lagrangian destroys the gauge invariance  BADOther problems as well.. Massive ForceCarriers • How do heavy quarks decay? • Why do neutrinos interact so weakly?

8. “Box” Diagrams “Tree” Diagrams +2/3 -1/3 “Penguin” Diagram Interactions via Feynman Diagrams

9. The (sub)Standard Model • Success as a description of observed phenomena • Many key questions unanswered • Why 3 generations? • Hierarchy problem? • Why do the quarks (leptons) have the masses that they do? • Are the forces unified at some high energy scale? • How does gravity fit in? • Is the dark matter a new BSM particle?

10. Weak Interaction and CKM • Photons and gluons couple to “flavor” (quark) eigenstates • BUT, weak interaction eigenstates  flavor eigenstates.CKM elements give relative strength of CC transitions amongst the 3 families • VCKM is 3x3, Unitary  3 real parameters, 1 phase. • Phase  0  Decay rates of particle  decay rates of antiparticle • Note: for 2 generations: Only 1 real par, Cabibbo Angle, sinqC=0.22 (to a specific final state) CP Violation No “SM” mechanism for CP Violation with only 2 generations

11. Huh, what is “CP”?Symmetries of Nature • Continuous Symmetries • Translational symmetry  Conservation of Linear Momentum • Rotational Symmetry  Conservation of Angular momentum • Time shift symmetry  Energy conservation • U(1) gauge symmetry  Conservation of electric charge • Discrete Symmetries • Parity (“mirror” symmetry): x  -x • Charge Conjugation: Particle  Antiparticle • Time Reversal: time  -time • The fall of discrete symmetries • Parity Violation – C. S. Wu et al, 1957, 60Co60Ni b decay, WEAK INTERACTION • CP Violation – 1964, Christenson, Cronin, Fitch & Turlay, KS = CP+, KL=CP- • If CP conserved in Weak Interaction  [CP,H]  CP Eigenstates also Weak Eigenstates. • CCFT observe that the “CP odd” state, KL  p+p- (CP even) ~ 10-3…CP Violation! • Large asymmetries expected in B decays, observed at Belle & BaBar (~2001) • CP Violation is a key ingredient to generating the BAU  Intimately tied to our very existence

12. Triangle inComplex Plane • (r,h) contains SM prescription of CP Violation, thus allowing for a matter/antimatter asymmetry • BUT, the amount of CP Violation is ~billion timestoo small to account for observed BAU. • Additional sources of CP Violation (BSM) “must” be lurking • Worldwide assault, multi-pronged, on measuring (r,h) • Length of sides • CPV angles • LOOK FOR INCONSISTENCIES ( r, h ) a g b (0,0) (1,0) CP Violation & Unitarity (Triangle) Taking into account the magnitudes of the elements, oft used Wolfenstein parameterization

13. l n Vub u b Vtb Vtd B0, Bs Mixing Vtd Vtb top quark dominates loop B0 B0 B0 B0 B0 B0 B0 B0 B0 B0 Mixing buln CLEO Dt (ps) Constraining the UT Measuring Sides of the “b-d” Triangle ( r, h ) a B0 B0 B0 B0 B0 g b (1,0)

14. l n Vub u b Vtb Vtd bulnB(p,r) ln B0, Bs Mixing Vtd Vtb top quark dominates loop B0 Mixing buln CLEO Dt (ps) Constraining the UT Measuring Sides of the “b-d” Triangle ( r, h ) a g b (1,0)

15. “Form factor” f+(q2), encapsulates the long-distance QCD effects as afunction of momentum transfer (q2). Effectively, gives probability for theformation of the final state hadron Hadronic plague • We want to get at the quark-level process, but often we measure hadrons. • The weak interaction physics we want is augmented by the strong dynamics between the quarks Example 1: Semileptonic Decays Normalization of f+(q2), taken from theory (lattice QCD, etc) Experiment can measure the shape, test shape predictions from theory 

16. Example 2: B0B0 Mixing Theory errors dominant on Vub and Dmd/ Dms a W- (r,h) W+ Requires theoretical input, e.g., lattice QCD Reduced uncertainty in the ratio: Hadronic plague • We want to get at the quark-level process, but often we measure hadrons. • The weak interaction physics we want is augmented by the strong dynamics between the quarks

17. Cracking CKM: Sides vs Angles • Large Errors • Large overlapregion… • New Physicsmasked! Angle Measurement Angle Measurement Side Measurement ( r, h ) a Side Measurement g b (1,0)

18. Cracking CKM: Sides vs Angles Reduced errors  New Physicsrevealed !! Angle Measurement Angle Measurement Side Measurement ( r, h ) a Side Measurement g b (1,0)

19. VtdVtb*=Al3(1-r-ih) a,b,g can be measured via asymmetries, which expose the interference terms (which contain the CPV angles). Time Evolution of B0 and B0. ME for decay: Compute Weak Inter. Eigenstates Hocus, pocus, after some algebra q/p is the phase of B mixing W- W+ Direct CPV Term Mixing induced CP Violation term Measuring the CKM Angles • We also must measure the angles of the UT. • Interference between 2 (or more) amplitudes with differing phases

20. Belle(Preliminary) Born as B0 B0J/yKS W- A(t) Born as B0 W+ |l|=1 Cf = 0 1 amplitude |A/A|=1 K0 Mixing B Mixing Vcs K0 Vcb J/y J/y Measuring Angles: sin(2b) in B0J/yKs Im(l) = sin(2b) A(t) = sin2b sin(Dmt)

21. Indirect “measurements” of the top quark mass from precision EW observables Indirect determination of top quark mass fromB mixing (1993, before top discovery) Barger et. al.PRL 1990, 4 years beforetop was discovered! Log L Direct (2006)171.4±2.1 GeV Top mass (GeV) • Bounds on Standard Model Higgs mass obtained using precision EW, MW, Mtop! H W t W W W W W W b H H Loop diagrams & discovery

22. New Physics • If there is New Physics at some large mass scale, AND it couples to SM particles, it will modify SM observables. • How might the New Physics manifest itself ? • New particle X produced directly (requires Ecm 2*MX) • Affect rates of processes involving LOOPS (penguin, box diagrams) • B mixing, FCNC, (g-2)m , etc. • Produce observable signals where SM rate ~ 0 • Rare B decays, D mixing, CP Violation, proton decay, etc.. • Plan of attack in B,D decays • Measure (r,h) using a variety of techniques: • Vub – SM Trees dominate • B(s) mixing - Loop diagram, NP can compete, but SM passed test so far. • Measure CKM angles using TREES only vs LOOPS only. Do we get the same result? If not, evidence of new physics! • Search for rare/SM forbidden decays (generally involve loop diagrams) • Key is to make a multitude of measurements and look for inconsistencies • Hadronic uncertainties need to be understood/quantified • Ideally make measurements in which hadronic uncertainties are “known” to be small

23. How does CLEO-c Fit In? • To conclude New Physics in B, D decays, one needs tounderstand (uncertainties from) hadronic effects.(in some cases, they’re expected to be negligible) • Several key measurements are limited by: • theoretical errors on non-perturbative hadronic parameters • Poorly known D decay branching fractions (normalizes B BF’s) • Resonant substructure of DXYZ, e.g., DPZ, PXY, etc • Final state interactions effects. • Primary goals of CLEO-c are to provide precision measurements to test models/theories, such as lattice QCD, in predicting non-perturbative matrix elements. • Precision tests in D decays provide a crucial test for any theory/modelattempting to predict similar quantities in B decays.

24. e+e- y(3770)  DD D e - D e+ The CLEO-c Experiment Collide electrons and positrons, Ee=1885 MeV, each • No extra particles, ED = Ebeam! • 93% of 4p coverage • Unobserved particles can be inferred via (E,p) conservation (neutrino reconstruction) e+ e - CLEO-c

25. e+e-y(3770)DD K Dsig e+ e- Dtag Kinematic Variables: p p p • Fully reconstruct one D (“tag”): Single tags • Other charged particles + photons MUST come from the other D meson (Dsig). • Absolute branching fractions can be computed, independent of s, L • Needn’t fully reconstruct Dsig. If 1 particle is missing from decay, missing mass ( MM ) is the signal. • Used extensively for analyses involving n’s ! Cleo-c Analysis 101

26. q=s,d A Sampling of Physics from CLEO Leptonic Decays Semileptonic Decays Hadronic Decays q=s,d

27. Currently limited by uncertainty in fB W- W+ Would you want to tell your daughter that we don’t have a clue as to why we exist? Leptonic Decays & the Decay Constant Recall _

28. W- _ W+ Vub b Getting to fB? • Currently, (unquenched) lattice QCD predicts fB with O(10%) uncertainty. Further reductionof uncertainties are possible in the “near” future. fB/fBs predicted to ~4% • Experimental prospects: • fB can be measured in B decays, B+l+n. • l = e,m experimentally possible, but rate is tiny! ~10-7(m),10-12 (e) • BF(B+t+n)~10-5, but experimentally more challenging (t decays, neutrinos) • Belle recently reported ~20 events from ~500 million BB sample…need much moredata to make this measurement meaningful.. fB gives the wavefunction overlap amplitude. How can we “test” decay constants predictions/uncertainties of lattice QCD?

29. or cs (s) D(s) Leptonic Decays CLEO-c: Test lattice QCD in predictions of D and Ds decay constants n K Dsig e+ e- Dtag p p m Ecm = 3770 MeV • Reconstruct a “Dtag” in one of 6 decay modes • Compute missing mass recoiling against the Dtag + m • MM2 peaks at 0 for D+m+n

30. n K 6 Tag Modes ~150K D± Tags Dsig e+ e- Dtag p p m D+ KLp+ D+ m+n D Leptonic Analysis • 50 signal events • Background ~ 3 events

31. e+ e- e+ e- n n K+ K+ Ds Ds* Ds Ds g Ds Ds* Ds Ds g Ds Ds g Ds g Ds K- p+ p+ K- m m Ds Leptonic _ • Higher energy beams required to produce DsDs • Largest rate at Ecm = 4160 MeV, but DsDs* dominant (Ds*Dsg ~ 95%). • Two cases need to be considered: • Enough constraints to deal effectively with the extra photon from Ds*Dsg. • Two analyses: • Look for Ds + mn, similar to D+ mn. • Look for Ds+ t+n, t+p+n • Exploit fact that p and m interact differently in the detector (calorimeter)

32. DStn, tpnsimulation Ds Leptonic MM2 DS+→m+n signal • Subsample 1: “Muon”-like (ala D+mn analysis) • Require Edep<0.3 GeV from track in CC. • Non-negligible pion leak-through • Subsample 2: “Pion”-like • Require Edep>0.3 GeV from track in CC Subsample 3: “Electron”-like Require Edep~ p

33. D(s) Leptonic Results B(DS+→m+n)=(0.657±0.090±0.028)% B(DS+→t+n) = (7.1±1.4±0.03)% fDs= (282 ± 16 ± 7) MeV Data consistent with most models. Better precision neededin both experiment & theory Subsamples 1 & 2 Combined withexpectation from simulation of D+m+n and D+ t+n ! (100 signal candidates!)

34. Future of Bottom/Charm Physics • It’s CLEAR we need: • Reduced hadronic uncertainties. • Adequate tests of theories/models of hadronic par’s. • CLEO-c (thru mid-2008) • BES-III (China, similar scope to CLEO-c, ~10X more data, exp. start around 2008) • More precise measurements of CPV in B0 decays • CPV angles: TREES vs LOOPS • CPV in Bs decays is a high priority • Rare/SM forbidden B(s) decays • New Physics in LOOP diagrams LHCb B Physics at the LHC

35. 250 mrad 10 mrad p p LHCbPrecise Measurements of CPV and Rare Decays TT

36. 2 kHz output to tape Full detectorinformation p p • HLT: • Confirm Level-0 • Associate PT/IP • Reconstruct Displaced Vertices Level-0: pT of m, e, h, g 1 MHz 40 MHz LHCb 39 MHz 998 kHz Software + lots o’ CPU L0: custom hardware Why do B Physics at a pp Collider

37. Test BeamSetup from Aug 06 ! Left & RightModule Distribution of unmixed sample after 1 year (2 fb–1) assuming ms = 20 ps-1 st ~ 40 fs 0.1 mm 10 mm Bs→Ds-π+ Time Resolution B Reconstruction

38. Need to know the “flavor” of the B when it was “born” ( b or b ) d • Flavor Tagging Methods for Signal B Meson • Same side kaon, K+ b, K-  b(points back to the PV) • Away-side kaon, K-  b, K+  b(does NOT point back to PV) • Away-side lepton tag, l -  b, l +  b(does NOT point back to PV) • Vertex charge: Q<0  b, Q>0  b b b b b b b b b Bs s u K+ ~10-23 [m] B0 Flavor Tagging Boom Methods 2-4 are degraded by the fact that the away-sideB meson mixes ~ 25% of the time before decaying ! Expect “Efficiency”, eD2 ~ 7.5% for BS & 4.3% for Bd

39. LHCb Key Measurements

40. Status in Pictures MUONSYSTEM Electromagnetic Calormter RICH2 (PID) MAGNET

41. Many reasons to believe SM is only an effective theory • Flavor physics may provide critical input to a more fundamental theory • Studies of B decays at e+e- machines • CKM sides limited by theory errors • CLEO-c paving the road to reduced theory errors • Precise (O(5%) meaurements of sin(2b) • Progress on a, (s~15o) • Only loose constraints on g as of now • B factories have performed marvelously, but are statistically limited. • The torch will be passed to LHCb in 2008 (large bb cross-section in pp!) Possible impact of a LHCb measurementon  Possible scenario in 2007 before LHCb g  (LHCb) sin2 sin2 Summary

42. Backups

43. CF DCS K+ D0 p+ p- D0 K- G  |VcdVus|2 G  |VcsVud|2 CS Internal CF p+ K0 D0 D0 p- p0 G  |VcdVud|2 G  |VcsVud|2 CF/CS/DCS Decays • Diagonal elements ~ O(1) • Off diagonal are reduced bypowers of l ~ 0.22.

44. q=s,d X K Dsig e+ e- Dtag p p e Inclusive Semileptonic Decays In this analysis, the final state hadronis UNSPECIFIED. Measure the inclusive electron yield and momentum spectrum. Check Isospin symmetry: G(D0eX) = G(D+eX)? • Reconstruct D0 and D+ (TAG) • Identify electrons among “other” charged particlesAccount for: • efficiency • particle mis-ID (pe, Ke), etc • backrounds, such as conversions (ge+e-), p0ge+e-, etc, using wrong-sign electrons D0K-p+ D+K- p+ p+

45. Inclusive Semileptonic Results D  e+ X Isospin Symmetry respected Summing up exclusive final states (0- & 1-) Excusive 0- and 1- final states ~saturate the semileptonic width Perhaps another 5% (relative) still lurking… B(Do→K1(1270)e+n) *B(K1(1270) →K-p+p-) =

46. q=s,d q2 ~ max, pP~0 n P l l P q2 ~ 0. pP max. P n Rate  P3 Exclusive Semileptonic Decays BF (decay rate) provides a measurement of |Vcq|2 D D • The hadronic complications are contained in form factors, which can be calculated via lattice QCD, HQET, quark models, etc. • Charm SL decays provide a high quality lattice calibration,crucial in reducing systematic errors in the UT. • Techniques validated by charm decays can then be applied to B meson decays. • Two “approaches” • Test lattice prediction for shape of f+(q2). If it passes, use f+(0)  Obtain Vcq. • Take Vcq from CKM fits, test lattice prediction of f+(0)

47.  K- K+ - e+ Semileptonic Reconstruction UEmiss-|pmiss| Peaks at 0 for event witha single neutrino Convert BF’s topartial widths

48. Semileptonics, compared to LQCD Normalization FF Shapes Lattice predictions* Dpen f+(0)=0.64±0.03±0.06 • a=0.44±0.04±0.07 DKen f+(0)=0.73±0.03±0.07 • a=0.50±0.04±0.07 Assume Vcd = 0.2238 LQCD DATA FIT Vcs = 0.9745 LQCD DATA FIT C. Aubin et al., PRL 94 011601 (2005)

49. sDp+ p- p0 Determined by generatingthe process via MC methodsand a detailed simulatiion ofthe detector response. In many experiments, it is difficult to ascertain NDtot So, often measure the BF relative to a “well-known” one. In D decays, The “well-known” modes are (before CLEO-c): Branching Fraction Anatomy • D0K-p+ (error~2.3%) • D+ K- p+p+ (error~6.5%) • Ds fp+ (error~25%) CLEO-c can measure absolute branching fractions!

50. D e+ e- D Absolute Branching Fractions in CLEO-c Single Tags: Reconstructed one D meson Double Tags: Reconstruct both D mesons To first order, Bj is independent of tag modes’ efficiencies, s, L. ISR tail