Beyond the Standard Model at BABAR

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Beyond the Standard Model at BABAR

• Eli I. RosenbergStandard Model and Beyond in the
  LHC Era
• January 7, 2008

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The B Factories were designed to study the CP
Violation and the CKM Mechanism
1998
Multiple independent measurements of the angles
b -arg (Vtd), and g arg (Vub) and sides
2007
All UnitarityTriangle measurements consistent
with CKM model
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Measure Both Angles and Sides of UT
http//utfit.roma1.infn.it/
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Move focus to looking for new physics

• Overconstrain the CKM Triangle Multiple
  independent measurements of the angles and
  sides
• e.g. sin 2b is a precision measurement via
  charmonium modes
• sin 2b 0.680 0.025 (HFAG World Average
  summer 2007)
• sin 2b via s-penguins should give the same result
• Rare decays
• Physics Beyond the SM can affect rare B
  decays modes
• penguins and FCNC
• Couplings to charged Higgs
• Exotic Processes Lepton Flavor Violation,..
• The list is long and I will only present a few
  selected examples

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The BABAR Detector
Electromagnetic Calorimeter 6580 CsI(Tl) Crystals
1.5T solenoid
Cerenkov Detector (DIRC) 144 Quartz bars and
11000 PMTs
e (3.1GeV)
Drift Chamber 40 layers
e- (9GeV)
Instrumented Flux Return Resistive Plate
Chambers and Limited Streamer Tubes
Silicon Vertex Tracker 5 layers, double strip
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Detecting Particles in BABAR
SVT DCH ? High quality tracking (fiducial
volume 041 lt ? lt 2.54)
?(pT)/pT 0.13 pT ? 0.45
EMC ? electron/? ID , p0, ? reco
?E/E 2.32 E-1/4 ? 1.85
SVT DCH DIRC EMC IFR
DIRC ? charged particle ID K-? separation 4.2 ?
_at_ 3.0 GeV/c ? 2.5 ? _at_ 4.0 GeV/c
IFR ? KL, ? ID
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Data Sample
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sin2b from Penguin Decays
New Physics
Standard Model
new physics

NP weak phase
no weak phase from decay

• There is no weak phase in b?(qq)s penguin decays
• sin(2b) from interference with mixing just as in
  B ? ? KS
• contributions from suppressed diagrams expected
  to be small (Dsin(2b) 0.01-0.1)
• If new physics contributes a weak phase in
  decay, we would measure something different than
  sin(2b)

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Determination of b arg(Vtd)
Vtd
Mixing creates oscillations (pB0qB0) If B and B
can decay to common CP final state (f)
Vtd
?e2ib
Need to measure time dependent asymmetries
Note that for a single weak phase l1 and Sf
Im(lf) Cf0
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Need to Measure Time Dependencies
Reconstruct second B
Flavor Tag one B (determines other B flavor at
t0)
9 GeV x 3.1 GeV ??0.55
?z ? lt??gtc?t ? 260 mm
Dz
Dz
tagging and time resolution
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CP violation in Penguin Decays

• 2.6s discrepancy between sin2b in b ?
  ccs and sin2beff from penguins (naïve average)
• assumes quasi 2-body amplitudes (even for wide pp
  resonances e.g. r, f0)
• Interference with other amplitudes treated as
  systematic error
• Exception BaBar fK0S result extracted from TD
  Dalitz plot analysis of KK-KS

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CP Asymmetries in B0 ? K0Spp-
  arXiv0708.2097
383 x 106 BB pairs

• Full Time-dependent Dalitz analysis
• Contributions from K-(892), K- (1430), f0(980),
  r0(770), NR
• C, S and beff extracted from amplitudes (C and S
  constrained to physical range)

m(pp-) GeV
Large S in f0(980)KS, but non-parabolic
likelihood 4.3s gt 0 and 2.1s gt S(J/? KS)
CP asymmetry in f0(980)KS region
(no evidence for direct CP violation)
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New HFAG naïve Penguin sin2beff Average

• HFAG advises extreme caution when interpreting
  this average (assumption of Gaussian errors not
  justified for all measurements)
• Average now compatible with sin2b from b?ccs, but
  poor fit
• If f0K0S from B?KSpp is excluded
• No evidence for direct CPV in penguin decays

(2s from sin2b from b?ccs)
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Identifying B mesons at the ?(4s)
Beam-energy Substituted Mass
Energy Difference
Event Shape
BB Events
Continuum (qq)
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Radiative Penguins
Sensitive to new physics at leading order
FCNC absent in SM at tree level Helicity
suppression for photon
New BaBar Technique E? extracted from fits to
HFAG 07 B(B ? Xs?) (3.550.26) x 10-4 Agrees
with SM (NLO) (Hurth et al., NPB 704 (2005) From
Inclusive B measurements either by fully
inclusive or by sum of exclusives yield photon
energy spectra
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mES Fits lead to background subtraction
Clean but ? 0.3 for Breco tag Need to subtract
B ? p0/? bkgd
Presented at FPCP 07
Preliminary
bkgd region
after efficiency and resolution corrections
signal region
extrapolate to lower E?
(based on HQE fits to b?cl? and b?s? moments)
BF(b?sg) Eg gt 1.9 GeV (3.66 0.85 0.59) x
10-4
BF(b?sg) Eg gt 1.6 GeV (3.91 0.91 0.63) x
10-4
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B ? XSg Summary
NNLO calculations are not final new calculations
with smaller errors are expected
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Charged Higgs Mass Implications
tan b 2
b ? s? gives a lower limit on a type-II Higgs for
any tan ß
95 CL lower bound on MH
MH gt 295 GeV (95CL) MH 650 GeV
Misiak updated by Nakao LP07
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Radiative s-penquin at the Upsilon(5S)
Reported by Belle at EPS 07
based on 23.6 fb-1
Ball et al, PRD 75 054004 (2007)
Preliminary
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B ? d? Exclusive Penguins
316 fb-1 PRL 98 151802 (2007)

• Study of exclusive decays
• B ? ?? B0 ? (?0, ?)g
• Suppressed by ?Vtd/Vts?2 ? 0.04 wrt
• b ? s? ? BF 10-6

B ? ??
B0 ? ?0?
B0 ? ??
isospin average
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B ? d? and New Physics
BF can be combined with BF for B ? K? to yield
ratio of form factors
accounts for different dynamics in decay,
e.g. annihilation diagram in r decay
Can be independently extracted from ?md/ ?ms

• 1.17 0.09 (Ball and Zwicky JHEP 604, 046
  (2006)
• ?R 0.1 0.1 (Ali et al, PLB 595, 323 (2004)

http//utfit.roma1.infn.it/
CDF PRL 97, 242003 (2006)
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Charged Higgs at the tree level

• Helicity suppressed by (ml2/mB2)
• BF ratio t m e 1 5?10-3 10-7
• So concentrate on ?

Vub b ? uln 8 error
SM Prediction
(1.5 0.4) x 10-4 for l?)
fB Lattice QCD 10 error
2HDM Isidori and Paradisi PL B639 (2006)
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B ? tnt is challenging

• Multiple neutrinos in final state
• So the analysis relies on identifying
• the tag side B (using either a
• hadron decay (B ? D()0X) or
• semileptonic decay (B ? Dl?)
• Then on the opposite side look for
• ? e??, mnn, pn, r(pp)n
• And then examine EM calorimeter for
• any extra energy

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Limits on Charged Higgs Mass
(arXiv 0708.2206) (PRL 97 251802 (2006))
2HDM
B??? only
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Another Charged Higgs Search
B ? D()t n
232M BB
arXiv 0707.2758
Confirmation of Belle observation in D, first
observation of D0 and first evidence for the D
modes.
3.5s 6.2s
G(B ? Dtn)/G(B ? Dln)

• tree-level NP

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FCNC in B0 ? ll?
347 fb-1

• B0 ? ll? strongly suppressed in SM
• b ?s,d quark transition, quark annihilation,
  lepton helicity suppression

Previous limits 90 CL
? 1.8x10-8 95 CL
This analysis 90 CL
arXiv 0712.1516v1
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FCNC in B ? K()ll
PRD 73, 092001 (2006)
210 fb-1
Both penguin and box diagrams Look for KS0 or
K and K with l pair
B ? Kll
mK?
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Branching Fractions for FCNC in B ? K()ll
BF (B ? Kll-) (0.34 0.07 (stat.)
0.02(syst.) x 10-6 BF (B ? Kll-) (0.78
0.19 (stat.) 0.11(syst.) x 10-6
SM Predictions have a 30 uncertainty from
hadronic effects
BF x 106
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Can also look for LFV B ? K()ll

• Lepton-flavor violating decay forbidden in SM
• enhanced in NP models (Sher and Yuan, PRD 44,
  1461 (1991))

BF (B ? Ke?) lt 3.8 x 10-8 BF (B ? Ke?) lt 51 x
10-8
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Recent Search for B ? Ktm
arXiv 0708.1303

• Fully-reconstruct B ? Ktm in recoil of other B

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B factories search for LFV in ? decays
At the ?(4S) , stt ? sBB ? 1nb
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? Measurements at BaBar

• taus are back-to-back (in CM), jet-like
• Examine the hemispheres in CM
• One hemisphere is signal
• Other hemisphere tag
• LFV decay is neutrinoless no missing energy
• Use kinematics for S/B separation

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BaBar Results on t ? l?
232 fb-1
t ? e?
Bkgd Bhabha, ISR and FSR in t ?
e?? BF(t ? e?) lt 11 x 10-8 PRL 96, 041801
(2006)
t ? m?
Bkgd mm ISR and FSR in t ?
m?? BF(t ? m?) lt 6.8 x 10-8 PRL 95, 041802
(2005)
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t ? l? vs. BSM Predictions
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t ? ?? and SUSY
Measurements are already limiting the parameter
space
BABAR t ? mg limit
SUSY SU(5) GUT Hisano eta l. Phys. Lett. B565
(2003) 183
SUSY SO(10) seesaw Masiero et al. NJP 6 (2004)
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gaugino mass
HFAG 2007 S?Ks 0.39 0.17
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New BaBar Results on t ? lll
(grey contours show areas of 50 and 90 of
selected MC events)
376 fb-1 6 modes studied
No significant signal observed! BR(??lll) lt
(3.7-8.0) x 10-8 _at_ 90 CL
PRL 99 , 251803 (2007)
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BaBar also has Results on t ? lhh
221 fb-1 14 modes studied
red are data points
No signals! BRslt (0.7-4.8) x 10-7 _at_ 90 CL
PRL 95 , 191801 (2005)
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? Decay Summary

• NO SIGNALS YET
• Limits (O(10-7 10-8)) have been set for 20
  modes
• Limits are at the upper end of the theoretical
  predictions
• We can probe SUSY region with higher statistics
• The background is under control (1/channel)
• 
  

From CERN Workshop FLAVOUR IN THE ERA OF THE LHC
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Related LFV Modes ?? lp0/?/??
BaBar PRL 98 061803 (2007)
M Sher, PRD 66 , 057301 (2002)
LH smuon-stau mixing
allows ???? limit to be interpreted as an
exclusion plot on the tan ß vs mA plane
Excluded region from this analysis 95 m? RH
1014 GeV introduced via seesaw mechanism
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B-L Conservation

• SM (B)aryon and (L)epton number are each
  conserved
• BSM B and L are not necessarily conserved
• Some models conserve B-L
• We can look for this in tau decays to baryons

B 0 ? 1 0 0 ? -1 0
L 1 ? 0 0 1 ? 0 0
B - L -1 ? 1 0 -1 ? -1 0
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Search for B-L Violation in t Decays
hep-ex 0607040 (ICHEP 2006)
237 fb-1
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Conclusions

• B factories play an important role in our search
  for New Physics
• (Present measurements already provide limits on
  Higgs models and SUSY, FCNC and LFV)
• Many more results to come as the size of the data
  sets continues to increase.
• This role is complementary to that of the hadron
  colliders (TeVatron, LHC)
• If the LHC finds New Physics, rare flavor decay
  can probe the details
• If the LHC does not find New Physics, rare flavor
  decays can still look for NP (will need higher
  luminosities).

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BACKUP SLIDES
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The Cabbibo-Kobayashi-Maskawa Matrix

• The weak and mass eigenstates of the quarks are
  not the same
• The changes in bases are described by unitarity
  transformations
• The net result is a unitary matrix which appears
  in the charged-weak current to describe the
  coupling of the quark flavors, i.e.

Unitarity VV 1 or VudVubVcdVcbVtdVtb0
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Identifying Bs The Golden Mode
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Another Charged Higgs Search
B ? D()t n
232M BB
Confirmation of Belle observation in D, first
observation of D0 and first evidence for the D
modes.
3.5s 6.2s
G(B ? Dtn)/G(B ? Dln)

• tree-level NP

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Summary of Results on ? ? l? or lll