TThhee BBAABBAARR EExxppeerriimmeenntt:: SSttaattuuss aanndd PPllaannss
Steven Robertson Institute of Particle Physics
Canadian Association of Physicists Congress 2008 Québec City, Québec June 10, 2008 OOuuttlliinnee
● Flavour physics overview
● The BABAR experiment and B factory operations
● Run 7 and ongoing analysis activities
● Some recent Canadian highlights
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 2 WWhhyy FFllaavvoouurr??
Flavour sector contains 20 (22) of 25 (27) parameters of the SM, which are intrinsically connected to EW physics and symmetry breaking
● Tantalizing structure (similarly for lepton sector) which is not predicted by the SM:
Vud Vus Vub ● All known CP violation phenomenology arises V = Vcd Vcs Vcb from a single complex phase in VCKM Vtd Vts Vtb ● B sector provides access to a substantial fraction of the CKM matrix either at tree level d or via one-loop processes * π V ud u ● Indirect probes of New Physics from b Vcb c “redundant” determinations of CKM + 0 parameters or from rare decay searches Β D u u Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 3 EEffffeeccttiivvee tthheeoorryy aapppprrooaacchh
● Loop-level flavour processes (FCNCs) can act as probes of mass scales far beyond the CM energies of accelerator-based experiments
In explicit models: Effective flavour- New Physics scale ● Λ ~ mass of virtual particles violating couplings
(e.g. Fermi theory.: mW)
● C ~ (loop coupling) x (flavour coupling) Increasing luminosity (e.g. SM/MFV: αw x CKM) Precision flavour measurements provide bounds on ratio C / Λ i.e. they constrain coupling strengths at any given mass scale
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 4 UUnniittaarriittyy TTrriiaannggllee ccoonnssttrraaiinnttss
● Unitarity of CKM matrix implies relationships between CKM elements which can be tested experimentally
● Bd meson Unitarity Triangle (UT):
B0 → π+π− 0 + − b → ulν B → ρ ρ B0B0 mixing
* b V u α td V V * d tb V u * γ VcdVcb β
B0 → D*π B → ψKS b → clν + 0 + B → φK B → D CP K S
● “Tree-level” determination of UT parameters permits the SM mechanism for CP violation to be tested
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 5 TTrreeeess vvss ppeenngguuiinnss
Unitarity of CKM matrix implies relationships between CKM elements which can be tested experimentally b→ccs J/ψ ● Bd meson Unitarity Triangle (UT): B0 B0 → π+π− K0 0 + − B → ρ ρ + b → ulν B0B0 mixing b→sss W u,c,t * V b s b ϕ u α td V s V * 0 g d tb B u V d s * d 0 γ VcdVcb β K New Physics g~ B0 → D*π B → ψKS b s ~ ~ ϕ b → clν b s + 0 + B → φK 0 s/d B → D CP K S B g s/d d d K0 ● “Redundant” determinations of UT parameters in modes which proceed via different mechanisms (i.e. tree vs loop) can yield information about possible New Physics contributions
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 6 TTrreeeess vvss ppeenngguuiinnss
● Determination of sin2β from ● Determination of sin2β from b→ccs modes consistent with penguin-dominated modes not overall CKM fit (both including as clearly consistent with SM and excluding kaon constraints): expectation:
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 7 RRaarree ddeeccaayyss
Searches for “rare” decay processes can provide additional NP sensitivity since the NP contribution may be comparable or larger than the (suppressed) SM rate
● Leptonic B, Ds or D decays:
● Flavor-changing neutral currents (FCNCs)
qi q j q qi j 2 (mq )23(13)
● Lepton flavour violation (e.g. in τ decays):
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 8 TThhee BBAABBAARR eexxppeerriimmeenntt
● Currently ~350 physicists from eleven nations
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 9 ϒϒ((44SS))
The ϒ(4S) is a bb resonance which d l o
lies just above the mass h s e
threshold for production of BB r h t
meson pairs. B B ● Cross section of ~1.1nb ~1.1 million BB pairs per fb-1
B0B0 pair is produced in The two B mesons evolve a coherent L=1 state in phase until one decays (EPR situation) PEP-II BABAR Off On
⇒ Enables studies of time-dependence of decays of “flavour-tagged” neutral B mesons ECM -M Υ(4S) (MeV)
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 10 PPEEPP--IIII AAssyymmmmeettrriicc BB FFaaccttoorryy
First collisions: 1998 Final collisions: April 2008 Collide 9.0 GeV electrons with 3.1 GeV positrons for ϒ(4S)
CM Energy = 10.58 GeV Design luminosity 3.0 x 1033 cm-2 s-1 Record luminosity 12.07 x 1033 cm-2 s-1
Number of bunches: 1720
Beam current: (HER) 1.875 A (LER) 2.9 A
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 11 TThhee BBAABBAARR ddeetteeccttoorr
B factory operations at SLAC since 1999: Magnet flux return EM calorimeter ● Centre of mass energy of 10.58 GeV instrumented with for ϒ(4S) → BB 6580 CsI(Tl) RPCs (→ LSTs) crystals ● Asymmetric beam energies produce 1.5 T boost of βγ=0.56 in lab frame solenoid
DIRC – RICH utilizing total internal reflection
) + σ e ( BABAR n (3.1 GeV) o i t K-π separation a r a p
e -
s e 5-layer silicon π
- (9.0 GeV)
K vertex detector 40 layer drift chamber (dE/dx) pLAB (GeV/c) σ /p = (0.13 · p /[GeV/c] + 0.45)% pT T T
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 12 BBAABBAARR//PPEEPP--IIII OOppeerraattiioonnss
● Final BABAR ϒ(4S) “onpeak” data sample corresponding to an integrated luminosity of 430 fb-1 ~0.5x109 BB pairs
● substantial samples of continuum tau and charm ● also ~45fb-1 of ϒ “narrow resonance” data (surprise!)...
●
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 13 IInntteerreessttiinngg ttiimmeess......
Run plan for Run 7 approved until Oct 2008 with luminosity target of ~2x1034 with anticipation of an additional ~50% new data
● substantial upgrades to accelerator during 3-month shutdown in fall 2007 ● BABAR IFR (barrel muon system) upgrade completed prior to 2007 run Dec 21st – Congressional budget cuts (targetted at ILC) result in termination of BABAR run Continues to Oct 2008 effective Jan 1st 2008
● BABAR successfully argues that physics case for ϒ(3S) & ϒ(2S) justifies a 3-month extension of the run End of ϒ(4S) Run ● PEP-II/BABAR retool Scan accelerator, detector and trigger system within a 3-day period ϒ(3S) Run ϒ(2S) Run over the holiday break
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 14 FFiinnaall OOppeerraattiioonnss
th ● Monday April 7 2008 (12:43PM)
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 15 NNaarrrrooww UUppssiilloonn PPhhyyssiiccss
● New element of BABAR physics 14.5/fb program: Upsilon spectroscopy! @ Y(2S)
● Search for elusive singlet states (ηb and hb) 7.3 0.3(stat) nb ( 7% syst.) ● Hadronic transitions, etc. ~100M ϒ(2S) (~12x CLEO) ● New Physics searches ● Invisible width of ϒ(1S), etc.
● World largest samples by one order of magnitude
● 30.2/fb @ Y(3S)
●
4.2 0.2(stat) nb ( 5% syst.) ~120M ϒ(3S) (x10 Belle, 25x CLEO)
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 16 DDiirreecctt HHiiggggss//DDMM sseeaarrcchheess ((??!!))
● Light (pseudoscalar) Higgs and/or light dark matter candidates can be directly produced in decays of heavy quarkonium states:*
● ϒ → χχ via U (new gauge boson or scalar) + - ● ϒ → A1 γ where A1 → χχ or τ τ Models manage to evade existing Higgs & SUSY LSP limits from e.g. LEP, while predicting quite large branching fractions Can have either completely invisible final states, or (invisible + γ), depending on spin of the mediator
● Require a “tag” to identify that the event has occurred
● Expected sensitivity with BABAR ϒ(3S) data sample Br(ϒ(1S) → invisible) ~few x 10-4 (prelim results “soon”)
*B●. McElrath, Light Higgses and Dark matter at Bottom and Charm Factories, arXiv:0712.00116v2 [hep-ph] J. Gunion, D. Hooper and B. McElrath, Light Neutralino Dark Matter in the NMSSM, hep-ph/0509024.
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 17 HHiigghh EEnneerrggyy SSccaann
● Last ~two weeks of Run 7 were dedicated to an energy scan of the region above the ϒ(4S)
● 25 MeV steps, 25pb-1 per point (previous scans by CLEO and CUSB in 1984 based on ~100pb-1)
● Motivation: study properties of ϒ(5S) and ϒ(6S) resonances, search for exotic bb states (analogous to “unexpected” Y(4260),Y(4350),Y(4660) charmonium-like states)
● Clear evidence of ϒ(5S) and ϒ(6S) resonances, but not a simple resonance structure
● interference contribution?
● ⇒ Results “soon”...
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 18 WWhhaatt nneexxtt??
● 3-month transition period to prepare detector for “Minimum Maintenance State” (MMS)
● Detector could (with difficulty) be brought back into service from MMS ● Requires continuous monitoring (e..g gases, fluids) but no expert shifters
● “Decommissioning and Disposal” (D&D) to begin in late 2008 or 2009 ● Planning underway – requires agreement between BABAR member countries ● Important to preserve valuable/unique hardware assets
● BABAR collaboration retains ownership of the detector until the end of MMS phase
● The lab will assume ownership at the end of MMS and the responsibility for the D&D
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 19 DDeetteeccttoorr rreeuussee ffoorr SSuuppeerrBB
● SuperB project (see talk in Monday morning session) assumes reuse of significant portions of the existing BABAR detector
DIRC CsI(Tl) barrel quartz calorimeter and bars support structure
Super- Muon conducting system solenoid iron/flux return (?)
⇒ Complicates D&D phase (issues of ownership, disposal and transportation costs etc)
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 20 PPoosstt ddaattaa--ttaakkiinngg ppeerriioodd
Post data-taking “intense analysis period” had been anticipated to begin in Oct 2008 following completion of ϒ(4S) run with total data set expected to be >700fb-1 of onpeak data
● Final “onpeak” ϒ(4S) data sample of ~430fb-1 ● Over 100 “core” analyses expected to be performed/updated with full data sample ● Many, many other analyses also currently in progress on topics ranging from new states, τ and charm physics, ISR physics, rare decay searches, B decays etc. ● New narrow-resonance studies well underway No evidence so far of any slowdown of analysis activities...
● 130 BABAR abstracts submitted to ICHEP08, 20(+2) talks! ⇒ SLAC has commited to providing computing resources through the intense analysis period – currently no obvious resource issues
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 21 PPuubblliiccaattiioonn ssttaattiissttiiccss
Published 320 PRL 165 PRD 66 PRD(RC) 114 Total Submitted 345
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 22 PPuubblliiccaattiioonn ssttaattiissttiiccss
Sustained publication rate of over 1 paper/week over the past four years!
● Very rich physics program: only ~half of all papers relate directly to primary BABAR program of CKM / CP violation
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 23 PPuubblliiccaattiioonn ssttaattiissttiiccss
● Asymmetric B factories still have only a very short history:
CP violation in B Current BABAR decays proves CKM grad students are born mechanism Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 24 LLeeppttoonniicc aanndd LLFFVV BB ddeeccaayyss ν π- ● Use hadronic tag reconstruction method to search for leptonic and lepton flavor B+ ϒ(4S) B- violating B decay modes µ+ K- ● Two-body decays yield clean signature in π+ signal B rest frame
Mode Data Sample 90% CL limit
PRD-RC 77, 091104 (2008) Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 25 VVuuss ffrroomm iinncclluussiivvee ττ→→KK ddeeccaayyss
● New precise BABAR measurements of τ decays to final states with charged kaons
● branching fractions consistent with, but lower than, previous measurements
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 26 VVuuss ffrroomm iinncclluussiivvee ττ→→KK ddeeccaayyss K .
M a
Currently a 3.4σ discrepancy with l t m
CKM unitarity! a n ,
C . ● Will be interesting (and important) E .
W
to see results from other modes o l f e ,
● 3 S
Bfactories each have O(10 ) .
B a
more data than LEP n e r j e e ,
M . R o n e y ,
I .
N u g e n t
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 27 BBAABBAARR SSyymmppoossiiuumm
● One-day symposium planned for Monday October 27, 2008 at SLAC to celebrate the achievements of BABAR/PEP-II
● Announcement/invitations anticipated to be sent out around mid-June
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 28 CCoonncclluussiioonn
● BABAR is still going strong, in spite of the untimely termination of the data taking phase
● Interesting (and unexpected) expansion of the physics program to include ϓ(3S) and ϓ(2S) bottomonium runs and a cross section scan above the ϓ(4S) ⇒ First results anticipated for ICHEP08 “Intense Analysis Period” is well underway (and living up to its name...)
● Full ϓ(4S) data set is in hand, many analysts freed from operational responsibilities ● Expected to be a record year for BABAR publications Canadian groups very active and productive, with interesting physics results spanning the spectrum of the BABAR program (B semileptonic and rare decays, charmonium and exotica, Upsilon physics, tau decays etc)
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 29 BBaacckkuupp sslliiddeess
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 30 TThhee FFllaavvoouurr PPrroobblleemm
Loosely stated, generic New Physics would imply observable effects which are are inconsistent with experiment unless either the New Physics scale is high (e.g. 1-0-100TeV) or the (loop x flavour) couplings are small
● F=2 processes occur at the loop level, thus could receive O(1) NP corrections but effects > ~20% are excluded NP < 1 TeV
● suppression of flavour violating couplings required in all sectors possibly pointing to MFV. SUSY can stabilize the Fermi scale with mild fine-tuning If 1< NP < 10-100 TeV
● suppression of flavour violating couplings needed in sector 1-2 only. No indication of MFV. SUSY can still stabilize the Fermi scale with moderate fine-tuning
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 31 NNeeww PPhhyyssiiccss BBoouunnddss ffrroomm ττ→→µµγγ
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 32 CCPP vviioollaattiioonn iinn iinntteerrffeerreennccee
● Measure CP violation in the interference between the decays of mixed and unmixed B0 decays t=0 B0 Af m CP t i x
-2iβ i CP ~e n fCP g y ca de A B0 f CP
● Combination of two decay amplitudes to the same final state manifests as an “interference pattern” in the measured decay rate as a function of decay time
-2iβ λfCP ~ e (AfCP /AfCP )
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 33 PPrreesseenntt FFllaavvoouurr CCoonnttrraaiinnttss
E.g. Model independent parameterization of New Physics NP SM contributions to B mixing amplitudes: 2iφ d QΔB2 QΔB2 Cqe SM QΔB2 Sensitivity (MFV) ~200GeV
1034 luminosity gives measureable effects if NP is at the EW scale BABAR/Belle purpose: “test SM mechanism for CP violation”
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 34 ΔΔFF==22 ppaarraammeetteerriizzaattiioonn
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 35 FFCCNNCC ddeeccaayyss uu cc tt dd ss bb ● Flavour changing neutral current (FCNC) processes do not occur in SM at tree level
● Loop-mediated processes can have large contributions from non-SM diagrams of same order as leading SM contributions: SM dominated by t-quark ● contribution
●
● Low-energy effective Hamiltonian for b →s (or d) transitions:
● Products of field operators (nonperturbative hadronic matrix elements;
HQE in inverse powers of mb) Wilson coefficients (calculated perterbatively; encode short-distance physics)
● New Physics can enter via non-SM values of Wilson coefficients
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 36 EElleeccttrroowweeaakk FFCCNNCCss
B → Xs/d γ
New physics could result in a distinctive pattern of deviations in observables across a variety of C (Photon penguin) only 7 related FCNC modes
Observables: branching fractions Eγ (or
mhad) spectrum, ACP
+ - B → Xs/d l l 0 + - B s/d → l l
C7 ,C9 (Vector EW) and C10
Observables: (partial) branching C10 (Axial vector EW) only fractions, dilepton A , A FB CP Observables: branching fractions
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 37 TTrreeeess aanndd PPeenngguuiinnss
● Time-dependent CP asymmetries in b→ccs, b→sss, b→qqs (q=u,d) ● b→ccs is tree decay clean sin2β measurement ● b→sss purely penguin decay: sin2β in Standard Model
● (0.05 hadronic), sensitive to heavy particles in loops ● “New Physics” potentially contributes at same order as Standard Model ● b→qqs proceeds via penguin diagrams and b→u tree diagrams g~ b s ~ ~ b s s /d New Physics g b→ccs s/d d d
W+ b→dds b→sss W+ u,c,t b s u,c,t 0 s 0 B g s b K 0 d d B g s 0 d K d d π0 d Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 38 BBeeyyoonndd TTrreeee LLeevveell......
● Tree-level charged Higgs (Type-II 2HDM or MSSM) contribution has the same effect on all leptonic modes:
+ + MSSM + + SM 2 2 2 2 ● B(B →l ν) = B(B →l ν) x [ 1 – (m B/m H+) tan β/(1+ϵ0 tan β) ]2
● “Universality” preserved at tree level
● At one-loop level, potentially large Lepton Flavour Violation (LFV) effects entering from e.g. SUSY in grand unification scenarios:
+ + + i.e. B → l νl' where l' ≠ l via effective l H ν coupling
l/τ Observable effects in ratios, Rb , of B leptonic branching ratios:
● ● Uncertainties from Vub and fB cancel in ratio of modes!
● ⇛ Can we get there??? G. Isidori and P. Paradisi hep-ph/0605012 ● A. Masiero, P. Paradisi and R. Petronzio hep-ph/0511289 Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 39 LLeeppttoonn FFllaavvoouurr VViioollaattiioonn
● In Standard Model, lepton flavour conservation is not associated with any underlying symmetry principle
● LFV generally permitted in New Physics models containing more than one Higgs doublet
● In SUSY seesaw models, flavour changing insertions arise from Yukawa couplings in the slepton mass RGEs:
● ⇛ New Physics effects in τ → l γ (l = e,µ) can saturate experimental bounds in natural and well-motivated models
-7 ● MSSM with heavy right-handed neutrinos and seesaw mechanism: Br~10
● heavy Dirac neutrinos, RPV SUSY models, flavour changing Z' models...
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 40 HHiiggggss mmeeddiiaatteedd LLFFVV
● Higgs mediated LFV present in MSSM at loop level given that there is a source of LFV among sleptons:
Effective SUSY
● Predicts LFV effects in a variety of τ and B decay modes (with preference for 3rd generation couplings):
From A. Dedes, Super B Factory proceedings: hep-ph/0503261 Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 41 P 466M BB FPC MMoorree CChhaarrmmlleessss RReessuullttss
+ • Observation of B → ηρ Submitted on full data set (arXiv:0804.2422)! ● Tree dominated decay
BR(B ηρ ) (9.9 1.2 0.8)10 6
ACP● B0R. 1in3 goo0d.1 a1gre0em.0e2nt with prediction 9σ signif. • Searches for B → η’ η, η’ π0, η π0, ωπ0 and B → ηK0, ηη, η’η’, η(’)φ, η(’)ω ● Input to ΔS from SU(3)-based theoretical predictions ● No signal observed 0 B ηKS ● All limits around ~10-6
2.6σ signif.
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 42 P 0 466M BB FPC CCPP AAssyymmmmeettrriieess iinn BB →→ JJ//ψψ ππ
● Cabibbo-suppressed mode with respect to 4σ evidence for CP violation, B → J/ψ KS and opposite CP consistent with tree-dominated decay ● Expect S = -sin2β and C = 0 BR(B0 J / 0 ) (1.69 0.14 0.07) 10 5 if tree dominated ψπ S 1.230.210.04 ● Penguin diagram or New Physics could modify CP asymmetries C 0.20 0.19 0.03
Submitted on full data set (arXiv:0804.0896)!
184 15 0 signal events B -tag
B 0 -tag
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 43 P 465M BB FPC CCPP AAssyymmmmeettrriieess iinn BB →→ KK ηη γγ
No significant CP violation, ● Radiative penguin decay consistent with SM ● Photon polarization different for B and B in SM, expect no interference and thus BR(B K ηγ ) (7.7 1.0 0.4)10 5
no CPV ACP 0.09 0.10 0.01 ● New Physics could contribute with BR(B0 K 0ηγ ) (7.12.10.4)10 5 different polarization amplitudes S 0.2 0.5 0.1 C 0.30.4 0.1 Submitted on full data set (arXiv:0805.1317)! B B 0 -tag
8σ signif. B 0 -tag B 0
3.9σ signif.
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 44 TTiimmee ddeeppeennddeenntt CCPP mmeeaassuurreemmeenntt
µ+ π+ J/Ψ - Exclusive µ B Meson 0 Reconstruction ϒ(4S) Brec - 0 π KS Exploit correlation e- + between B0 flavour e 0 Btag and lepton charge, K charge etc K- Reconstruct decay Δ z vertex positions l-
B-Flavour Tagging
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 45 P 466M BB FPC CChhaarrmmlleessss BB DDeeccaayyss ttoo bb1
+ 0 • Observation of B → b1 K Submitted on full data set (arXiv:0805.1217)! ● 6.2 σ significance
0 6 BR(B b1 K ) (9.6 1.7 0.9)10
ACP 0.030.15 0.02 ● consistent with QCD factorization 0 + • Search for B → b1 ρ ● VA modes may shed light on polarization puzzle in VV modes ● QCD factorization predicts:
0 ∓ 12 6 BR(B b1 ρ ) (3317 5 )10 – No B0 → b + ρ observed ! 0 ∓1 6 BR(B b1 ρ ) 1.710 (90% CL)
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 46 P F P C SSeemmiilleeppttoonniicc aanndd LLeeppttoonniicc DDeeccaayyss ((ww// SSLL ttaagg)) Submitted on full data set (arXiv:0805.2408)! 383M BB 0 0 ● Exclusive B → Xu l ν branching B π l ν l B π l ν l fractions 0 4 BR(B π l ν l ) (1.38 0.210.07)10 0 4 BR(B π l ν l ) (0.96 0.15 0.07)10 4 BR(B ηl ν l ) (0.64 0.20 0.30)10 4 BR(B η 'l ν l ) 0.4710 @ 90% CL B ηl ν l B η 'l ν l |V | (4.0 0.5 0.20.7 ) 10 3 ub 0.5 3.2σ signif. 454M BB
● Search for B → K* νν ● SM BR prediction ~10-5, but could be significantly enhanced by New Physics BR(B0 K *0νν ) 2110 5 BR(B K *νν ) 910 5
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 47 P FPC ((**)) BB →→ KK ll ll 384M BB
● Rare EW penguin decays BRs BR(B Kl l ) (0.39 0.07 0.02)10 6 BR(B K *l l ) (1.110.19 0.07)10 4
● Rate asymmetries (CP, isospin, e/µ) expected to be very small ● Measured separately in ll-mass region above and below J/ψ ● All rate asymmetries compatible with zero, except isospin asymmetry in low mass region for ee sample
ee 0.18 AI ,low s 0.83 0.16 (4.2 σ )
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 48 RRuunn 77
● Data taken between December 16, 2007 and April 7, 2008
● 30.2 fb-1 at ϒ(3S)
● 14.5 fb-1 at ϒ(2S)
● ~5 fb-1 above ϒ(4S) scan
● Several ϒ(3S) analyses and above ϒ(4S) scan targeting ICHEP 2008
Sep 3, 2008 The BABAR Experiment Steven Robertson, Institute of Particle Physics 49