e e- Annihilation into Quasi-two-body Final States at 10.58 GeV --Expected or unexpected?

1
ee- Annihilation into Quasi-two-body Final
States at 10.58 GeV --Expected or unexpected?
Kai Yi, SLAC

• Introduction
• Analyses of exclusive processes
• --ee-?????,??? (C1) TVPA
• --ee-???- (C?1 ? ) 1 ?TVPA FSI?
• --ee-??? (C?1 ) s dependence
• --ee-?p?p p?p fragmentation
• (very
  preliminary)
• Summary
• Outlook

2
IntroductionGeneral Information
Hadronic cross section
PDG 2006
?(ee-?hadrons) 3 nb _at_10.6 GeV

• The design goal of the B factory is the study
  of B physics.
• At ?s10.6 GeV, ?(ee-?hadrons) 3 nb and ltNchgt
  8
• Large integrated luminosity (500 fb-1) ? can
  study low-multiplicity exclusive hadronic
  processes with ? values fb this provides
  tests of pQCD at the amplitude level.

3
The BaBar Experiment

• ee- collisions at 10.6 GeV, designed for CP
  violation in B decays
• Different beam energies
• Ee- 9.0 GeV
• Ee 3.1 GeV
• c.m.-lab boost, gb0.55
• Asymmetric detector
• track coverage /4?0.92
• EMC coverage /4?0.90
• with excellent performance
  High luminosity
• Good tracking, mass resolution
  480 fb-1 accumulated
• Good g, p0 reconstruction.
  1.6 billion ee- q?q evts
• Good e,m,p,K,p ID
  0.5 billion ee- B?B evts
• Data sample for today ?L343 fb-1 _at_10.58 GeV
  (OnPeak) ?L36 fb-1 _at_10.54 GeV (OffPeak)

Barrel now has LSTs
4
Data input and physics output
BABAR
Luminosity 477fb-1
Journal Papers 312
Run 6
Peak luminosity (cm-2s-1) 1.201 x 1034
Best shift 329.7 pb-1
Best day 891.2 pb-1
Best week 5.25 fb-1
Best month 18.83 fb-1
BABAR logged 477 fb-1
5
IntroductionProcesses at B Factories
Two photon processes
One photon processes
TP
?nb
Todays topic
?fb
Exclusive hadronic final states
Two-Virtual-Photon-Annihilation, TVPA new
observation
A subset of ee-?q?q processes or via ISR, a
test ground for QCD
6
Observation of ee-?????/??? (C1)
7
Observation of ee-?????/??? (C1)
PRL 97, 112002 (2006)
Data
Select events with invariant mass of
(KK-??-/??-??-) within 170 MeV of c.m. energy.
_at_10.6GeV
We are interested in ????. assume m(?0)lt2.2
GeV/c2, p(?0)gt4.8 GeV/c Only one entry in
the region of interest (no ambiguity)
4.8 GeV
No entry
p?1?4
p?1?2
8
ee-?????/???--generate level simulation

• at 10.6 GeV, large kinematic separation between
  modes
• ...and between correct and incorrect
  pairings

????
9
ee-?????/???--scatter plots in data
signal tiles 0.5ltm??lt1.1 GeV/c2 (?)
1.008ltmKKlt1.035 GeV/c2(?)
lego
Use binned log-likelihood fit over 9 tiles to
extract signal Including components
rpp/rKK/fpp rmm rf2(1270) rr/fr
Threshold
10
ee-?????/???--mass projections
??- against ?
??- against ?
?
?
total
?? backgroundf2
f2
?? background
f2
Correlated ? and ?0 signals Relativistic
Breit-Wigner lineshapes used in the fit
KK- against ?
total
background
11
ee-?????/???--On-, Off-resonance comparison
The extracted signals
All Events Yield _at_ 10.58 GeV Yield _at_ 10.54 GeV Expected continuum _at_ 10.56 GeV (from ?L ratio)
?0?0 1243?43 gtgt 5? 1138? 42 104? 14 112 ?4
??0 147?13 gtgt 5? 135? 13 14? 4 13? 1
significance
Yield
consistent

• C parity conservation? Y(4S) production do not
  contribute
• Consistent with continuum production?combine
  On- and Off-resonance data.
• Signals large enough to analyze the angular
  distributions and investigate
• the production mechanism for these final
  states.
• First observation of (C1) hadronic final
  states in ee- collision. Likely by TVPA.

12
ee-?????/???--TVPA expectation for cos?
13
ee-?????/???--Angular distributions in data
Efficiency-corrected projections
Production angle ??polar angle of ? or ?forward
in CM consistent with expectation for TVPA
????
???
1cos2? for comparison
Helicity angle ?Hthe angle between daughter and
recoil in the mother rest frame
?0?0
??0
??0
sin2?H distributions as expected For TVPA with
quasi-real photon
?H for ?
?H for ?
?H for K
14
ee-?????/???--Cross sections

• The observed angular distributions support TVPA
  production

• The measured cross sections (1.008ltm?lt1.035 GeV,
  0.5ltm?lt1.1 GeV, cos?lt0.8)
• ?(?0?0)20.7?0.7(stat) ?2.7(syst) fb
  reminder
• ?(??0) 5.7?0.5(stat) ?0.8(syst) fb
  ?(ee-?hadrons _at_10 GeV) 3 nb
• Theory calculations (after the measurement)
  consistent with our results
• hep-ph/0606155
  hep-ph/0608200
• ?(?0?0) 21.4?0.7
  17.7?0.6 fb
• ?(??0) 6.0?0.1
  5.6?0.2 fb

15
ee-?????/???--VMD model calculation
M. Davier et al, hep-ph/0606155

• Assuming the ee- ? ?? process followed by
  conversion of ? into V1 and V2, with
• effective coupling e/f1 and e/f2 . The cross
  section in c.m. frame can be written as

• Obtain effective coupling through mesons
  leptonic width

• Calculation with this simple VMD model agree
  with our measurements.
• More calculations based on VMD are summarized
  in next slide

16
ee-?????/???--VMD model calculation
J/?J/?

• Belle first observed J/? ?c(c?c) at a level 10
  times higher than QCD prediction
• through missing mass recoiling against the J/?.
  
• J/?J/? was once proposed to explain the high
  rate. Its cross section was estimated
• to be 7 fb, now 2.5 fb (hep-ph/0608200).
• Not yet observed.

17
ee-?????/???VMD model calculation
Eur. Phys. J. 31, 503-510 (2003)
Spectral function

• Discrepancy between ? decay data and ee- data
  as input.
• Interpretation of ee- cross section ignores
  C1 process.
• How much TVPA contribute? One of our motivations

R value from ee-?VV(C1), cos?lt0.8,
(hep-ph/0606155)

• TVPA contribution to muon (g-2) is small with
  the current
• precision by extending our results to low
  energy
• Removes a possible uncertainty source in g-2
  calculation
• ?2/? (pi-rhonium, mixing of ? and pionium)?
• 0705.0757hep-ph

18
Observation of ee- ? rr-
19
Observation of ee- ? rr-
379 fb-1, BaBar Preliminary

• Single photon (JPC 1--)

• In general
• C(??-)(-1)LS, or -
• P(??- ) (-1)L
• Single photon production?
• L odd, S even, I(??- )1(Bose Statistics).

• Other possibility TVPA (C 1) followed by FSI
  ? unlikely?

No angular correlation predictions for this
mechanism
20
ee-?rr- QCD prediction and event selection

• Three independent helicity amplitudes F00, F10,
  F11, if one ? production assumed.
• One QCD model predicts (PRD 24, 2484) s
  dependence and production angle
• ?F00?1/s2, sin?2 ?F10lt1/s3, 1cos?2
  ?F11lt1/s3, sin?2
• _at_10 GeV, F00 is expected to dominate.
• Test QCD at the amplitude level in helicity
  structure.
• Select
• two tracks p and p- two good p0gg
• momentum balance, mp?p0 lt 1.6 GeV/c2
• mpp0p-p0 - ECM lt280 MeV

21
ee-?rr- Scatter plot and mass projections

• Clear signal for ee- ? rr-
• 2D Likelihood Fit in (m?-?0, m??0 ) plane
• Signal function product of P-wave relativistic
  BWs
• rpp threshold function
• Linear combinatorial background

Mass projections
22
ee-?rr- Cross section

• We observe 308 25 signal events (gt 5?).
  (fiducial) cross section is 8.50.71.5 fb
• (cos?lt0.8, cos??lt0.85, 0.5ltm??lt1.1)
  
• Extend to full angular range assuming 1 ?
  production
• ?(ee- ? ??-) (20.0 1.6 3.6 1.7) fb
  preliminary (no prediction)
• ?(ee- ? ?0?0) 130 fb hep-ph/0606155
• ?(ee- ? ?0?0)gtgt ?(ee- ? ??-) FSI possible
  explanation?
• No evidence for Y(4S) ? ??- .
• ee-???- seen in ISR data ee-??0?0 is not
  seen in ISR as expected.
• Will study cross section s dependence using ISR
  data and this result.

23
ee-?rr- Coordinate system

• Assuming one-virtual-photon (JPC1- -)
  production, the total spin S and orbital angular
  momentum L should satisfy (in L-S coupling)

?
?

• Our coordinate system

• ?--production angle, ? is not well defined
  (beam depolarization)
• ?--? helicity angle, ?-- ? azimuthal
  angle
• Similar for ?-

24
ee-?rr- Angular correlation calculation
In helicity basis, the decay amplitude of a
two-body decay (PRD 57 431, 1998) Can be
expressed as
25
ee-?rr- Angular correlation calculation
In terms of JP, ee- ? rr- can be expressed as
1-?1-1-, we have the following helicity
configurations (?,?) (1,1), (1,0),
(-1,-1),(-1,0), (0,1), (0,-1),(0,0), (1,-1),
(-1,1) (angular momentum). The remaining
possible amplitudes are
F11, F10, F-1-1, F-10, F01, F0-1, F00
?
CP conservation ?
i.e. only 3 independent amplitude
26
ee-?rr- Angular correlation calculation

• IA2, complicated angular distribution. Due to
  low statistics, we only
• investigate individual angular projection by
  integrating over the other angles

• By integrating, we lose strong phase
  information.
• The most separation power is from dN/dcos??.
  The F00 amplitude contribution
• goes to zero for ??90o .
• The amplitudes are correlated intensive Toy MC
  has been done to validate
• the procedure. No bias is found from Toy MC
  studies.

27
ee-?rr- ? correction and background
subtraction

• Efficiency corrections to angular distributions
• --non-flat dependence of ? on cos? and cos??
• --use a 3D(cos?,cos?,cos?-) table to correct
  each event
• --the method is validated on an independent MC
  sample.
• Background subtraction using sPlot
• --weight each event by sWeght obtained from 2D
  mass fit
• --consistent with conventional way.
• Weight each event by sWeight and ? to produce
• signal angular distributions.

28
ee-?rr- Fit to the projected angular
distributions
BaBar Preliminary
Helicity angle
Non-zero amplitude? F00 1
Simultaneous fit to the five distributions. F00
dominates but Cannot explain all pQCD
predicted F001, and
Azimuthal angle
Production angle
29
ee-?rr- Amplitude result

• Fit normalization constraint

• Results

x4
x2
F002 ? 1, s(ee- ? r0r0) gt s(ee- ? rr-) no
evidence for Y(4S) ? rr

• Are we seeing TVPA FSI?
• --Combine with ongoing ISR analysis to measure s
  dependence of the
• cross section for each individual amplitudes to
  investigate FSI.
• Any connection between B?VV polarization puzzle
  and ee-?VV?

--Prediction
--BaBar Data
30
Observation of ee-??? at 10.6 GeV
31
Observation of ee-??? at 10.6 GeV
PRD (RC) 74, 111103(2006)

• ee-? ?? is analogous to ee-?J/??c (? has s-sbar
  content)
• Interesting because observed ?(ee-?J/??c )
  10x higher than QCD predictions
• Provides information on s-dependence by combining
  with a CLEO measurement at lower energy
• Select
• -- exactly two tracks, identified as K
  and K-
• --two good g candidates with deposited
  energy greater than 500 MeV
• --momentum pKK-??lt0.2 GeV/c in the c.m.
  frame
• -- a pairing with both mKK- lt1.1 GeV and
  0.4ltm?? lt 0.8 GeV/c2
• --select events within 230 MeV of the
  nominal ECM

32
ee-???--Signal and scatter plot
PRD (RC) 74, 111103(2006)
?
_at_ 10.58 GeV
_at_10.5810.54 GeV
?
We see ?? correlation. Use a two-dimensional
log-likelihood fit to extract signal P-wave
relativistic Breit-Wigner for ? Gaussian
resolution function for ?
33
ee-???--Mass projections
Mass projections
Yield for 1.008ltm?lt1.035 GeV/c2, and 0.4ltm??lt0.8
GeV/c2 All data 24?5 events _at_10.58
GeV 20?5 _at_10.54 GeV 3?2 Significance
6.5 ? U.L. for BF of Y(4S) decay _at_90 CL based
on -10 ? 21 events 2.5X10-6
34
ee-???--Coordinate system

• ?(1--), ?(0-), ?(1--), P conservation? L1,
  assuming one ? production.
• In helicity base, we have only one amplitude
  F10.
• (F00 is forbidden due to vanishing CG
  coefficient)
• We have a similar coordinate system

We ignore the ? decay angular distributions, they
are flat.
35
ee-???--Angular correlation calculation
Similarly, we can calculate the total helicity
amplitude as
36
ee-???--Angular distributions

• Due to low statistics, we investigate the
  angular projections by integrating
• over the other angles

• Weight isotropic MC angular distributions as
  above to obtain efficiency estimates.
• The efficiency dependence for each angular
  distribution is approximately flat, which
• simplify the correction procedure.
• Distributions in data are consistent with
  predictions within the limited statistics

37
ee-???--Cross section
For 1.008ltm?lt1.035 GeV/c2 and cos?lt0.8 , the
cross section after radiative corrections is
measured as
?(??)2.1?0.4(stat) ?0.1(syst) fb Extending to
(cos?lt1) by assuming a 1 cos2?
distribution, this becomes
?(??)2.9?0.5(stat) ?0.1(syst) fb
Combine with CLEO measurement at lower energy
1/s3 energy dependence favored over 1/s4 (pQCD
prediction), assuming continuum production.
Analysis of BaBar ISR data is ongoing see
preliminary result next slide.
Recent theory prediction (after the measurement)
(hep-ph/0702065) ?3.14.3 fb, and 1/s3
dependence favored.
38
ee-???--Preliminary result from ISR
BaBar Preliminary

• BaBar preliminary ISR (?ISRKK??) result
• possible structure(s) near 2.2 GeV

• At high-ECM, data (including 10.6 GeV point)
  are consistent with 1/s4
• CLEO measurement seems to be low.
• Dispersion relation phenomenology EPJ A31, 665
  (07)
• --explains the data nicely in terms of ? and
  ? resonances
• --confirms 1/s4 asymptotic behavior, it is
  actually helicity F10 amplitude
• implies that pQCD is right, favor FSI for
  ee- ? rr- .

39
Connection to LHC

• Angular correlations to determine JPC of X(H)
  particle
• --Simple way assume one configuration,
  compare to data
• --General way assume all configuration, decide
  the best one.
• e.g., X(H)?ZZ
• sPlot to subtract background. i.e., H?ZZ (may
  not needed)
• Test PYTHIA prediction. Help refine the
  fragmentation model of PYTHIA
• for a more precise modeling of the jet
  content.
• Even the energy at BaBar is low compare with
  LHC, but we
• have information from data.

40
Summary

• At BaBar we have
• Made the first observations of the TVPA
  hadronic processes
• ee-????? and ee-????
• and the angular distributions support TVPA
  mechanism.
• Observed the process ee- ???- the measured
  helicity amplitudes contradict a pQCD expectation
  at 3.5 ?, assuming single ? production.
• --Further investigation using ISR data on ee-
  ???- will provide information on the s
  dependence and perhaps on understanding of the
  role of FSI (if any).
• Observed the process ee- ??? and measured the
  cross section this provides an interesting
  test of the QCD prediction for the energy
  dependence, assuming continuum production.
• Observed ee- ? p?p p?p, presently being
  investigated.

41
Outlook

• We also see evidence of many other exclusive
  final states. Results from these
• channels will provide further detailed tests of
  QCD and hadronization models.
• However
  
• B factories provide opportunity to search for
  new particles.
• X(3872), Y(4260), Y(4350), Z(4430), Y(4660)
  (unexplained)
• Z(4430), if confirmed, has strong implication
  for other states.
• May classify them as multiple-quark states,
  hybrid, glueball,
• Glueballs and hybrids gain mass through the
  strong interaction (solely for
• glueball). A unique place to study mass
  creation by strong interaction.
• (i.e., proton gains only a few percent of its
  mass through Higgs mechanism)
• lots of
  activities are going on

42
Outlook

• More fundamental question How bosons,
  fermions gain mass?
• The Higgs mechanism?
• Updated W and top quark masses improved
  constraint on
• Higgs mass MH 76 31 GeV (dmH/mH 39)
  (winter 07)
• LEP limit gt114.4 GeV _at_95 CL
• New possibilities proposed
• --H?2a?X, a is non-SM particle.
  (hep-ph/0608310)
• --CP-Odd NMMSM A0???.(hep-ph/0404200,
  hep-ph/0612031)
• (put BaBar in the game)

43
Outlook

• New idea at LHC Flavor Changing Higgs
  Decays (FCHDs)
• BR is estimated to be about 10-4-10-3
• MSSM ?(h0,H0,A0)?b?s, Phys. Lett. B 647, 36-42
  (2007)
• QCD background free, challenge on s jet
  identification (impossible?)
• Trigger possible?
• Some ideas on s jet ID (no guarantee to work)
• --pT of Ks/?/?/? Anything
  else?hep-ex/9702009, hep-ex/9908038,
• --impact parameter separates b (c) from s
• --Jet charge tagging separates up-type from
  down-type
• --use MVA technique to combine?
• --Topological Vertex help??
• 
  Thank you!

44
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