Title: Some Recent Results on Charmonium and Charm Decays from CLEO
1Some Recent Results on Charmonium and Charm
Decays from CLEO
Celebrating 30 Years of Physics Results from CLEO
John Yelton University of Florida
2- My talk will be
- A retrospective look at 30 years of CLEO ee-
- physics
- 2. Some recent results on
- a) hc (L1 singlet charmonium state) physics
- b) Leptonic decays of charmed mesons and the
decay - constants fD
(s)
3CESR/CLEO Prehistory
Directors
Bacher
4CESR/CLEO Prehistory
- Decades of Cornell synchrotrons, beginning late
1940s, culminating with 12-GeV Wilson
Synchrotron (1968)
- First discussions of colliding beams 1973-74,
with major boost from J/?. - Idea Explore ee- collisions in 8-16 GeV
center-of-mass range, hope for something new - Competition PEP at SLAC, DORIS PETRA at DESY
- CESR proposed May 1975
- 8 GeV ? 8 GeV in synchrotron tunnel, design
luminosity 1032 cm-2s-1, 2 IRs, clever design to
maximize reuse of 12 GeV infrastructure
- RD for South Area Experiment started in 1975
design settled construction under way by late
1977
5Surprise After detector design
started.Discovery of hidden b by Lederman and
colleagues at Fermilab (p N ? ? ?- X at
400 GeV) .
Two upsilon states - confirmed by DORIS. A
third? More?
6 CLEOs 1979-80 To-Do List
- Verify the Fermilab and DORIS observations of the
? states. - Search for additional states. Spectroscopy tests
bb hypothesis and states above threshold should
decay to particles carrying the new flavor. - Could there be a state for threshold B
production analogous to the ?(3770) for Ds? - Measure masses, branching fractions, other
properties to verify that b has been found and is
the fifth quark of Kobayashi and Maskawa. - Or not!
7The Machine
- Cornell Campus
- Originally two
- interaction regions
- CUSB
- CLEO
8 Inside the CESR Tunnel
Same tunnel, same synchrotron, with CESR, c. 2000.
Boyce D. McDaniel Hans Bethe in 12-GeV
Synchrotron Tunnel, 1968.
9CESR/CLEO first data late 1979
0.4 pb-1
10The Original B Factory
1.1 pb-1
- ?(4S) discovered early 1980 with 1090 nb-1 of
CESR scan data - (ECM 10.46-10.64 GeV)
- 1 nb enhancement in multihadron production,
broader than other ?s - Much agonizing over whether it was real 1st use
of continuum suppression
Newsweek, August 11,1980 Beauty is Found Where
is Truth?.
11Measures of CLEOs Impact
- Longest-running expt. In HEP history?
- Excellent Record of Publication
12Measures of CLEOs Impact
- 508 papers in Phys. Rev Letters, Phys. Rev. D etc.
- Topcite papers in HEP SPIRES data base
- 250 7 papers 100 56 papers 50 140
papers - (Equally distributed by decade)
- 231 CLEO Ph.D. students (several still on the
way)
13Why was CLEO so successful?
- The detector was kept up to date
- CLEO ? CLEO 1.V ? CLEO II ? CLEO II.V ? CLEO III
? CLEO_c - (new drift chamber)
(silicon) (no
silicon) - ( CsI calorimeter)
RICH
- Variety of physics. Not just B physics, but
charm (4 charmed mesons and 14 charmed baryons
discovered), and tau physics. - Collaboration stayed together
- Luck! If Upsilon was at 18 GeV, none of this
would have - happened
14(No Transcript)
15Why CLEO-c?
- CESR/CLEO III not competitive with newer B
factories - But, had state-of-the-art and flexible detectors
- Heavy flavor physics began in ee- studies of c,
but c had been neglected and studies of b and
particles decaying into b were limited by
knowledge of c - Interpretation of high-precision b measurements
limited by theoretical uncertainties (strong
interaction). New tools (Lattice QCD) needed
rigorous tests charm! - CLEO-c proposed Fall 2001, approved in 2003 and
collected data from Dec., 2003 until March, 2008
16Transition to Charm Threshold,
- CESR re-optimized for 4 GeV
- Inserted SC wigglers to increase
damping/luminosity - Much higher luminosity than previous experiments
- CLEO-c detector superior to previous charm
detectors
Ecm 4170 GeV 600 pb-1 0.57M DsDs
?(2S) 54 pb-1 27M ?
?(3770) 818 pb-1 5.1M DD
17CLEO-c Detector
- Covered 93 of Solid Angle
-
- Tracking
- ??p/p 0.6 _at_ 1 GeV
- Calorimetry
- ??E/E 5 _at_ 0.1 GeV
- 2.2 _at_ 1 GeV
- Charged PID (RICH dE/dx)
- Good K/? separation
- over entire momentum
- range (p lt 2.5 GeV/c)
18THE CHARMONIUM SPECTRUM
Notation n 2S1 L J
y(2S)
ccJ
n2
y(3770)
?c(2S)
hc
D mesons
J/y
2K,2K2p,4p,6p
?c
n1
ll-
S 0 1
0 1 0 1
L 0
1 2
19CLEO finding the hc Over 1,000 events
reconstructed
Method 1 look for bump in ?0 recoil mass
spectrum in events with a ? with correct energy
for hc ??c ? decay
20Method 2 use many (15!) different decay modes
of the ?c and completely reconstruct the event.
The two methods agree and are consistent with
the previous CLEO measurement.
B(?(2S)??0hc)x B(hc???c) (4.19 0.32
0.45) x 10-4 M(hc)3528.28
0.19 0.12 MeV ltM(?cJ)gt M(hc)
0.02 0.10 0.13 MeV
21But there is no reason that the hc has to decay
radiatively can it be seen directly into
hadrons? We looked in decays into odd number of
pions.
5? mode good signal 7? mode
hint of a signal
Product branching fraction indicates around 5 of
??c (indicates hadronic decays same order of
magnitude as radiative decays)
22BES III preliminary data based on 100,000,000
?(2S) events
Select inclusive p0 A fit of Gaussian signal
4th order polynomial bkg yield N(hc)
9233935 Combined inclusive and photon tagged
spectrum yields Br(hc???c) (55.76.3(stat))
of total decay rate (but systematics still under
consideration).
23(No Transcript)
24D(s)?l?l
- Premise
- Given the CKM factors, a measurement of the
branching fraction for a leptonic decay gives the
decay constant fP - A theory that calculates fP can be verified and
applied to other SM (CKM) measurements that mix
strong and weak - B0 and Bs mixing needs fBs/fB, Vub from exclusive
needs form factors
Lattice QCD (unquenched) is asserted to have
reached the needed precision. We need to test!
25D Physics with Tags
- ?(3770) provides large ?(DD)
- High efficiency tagging of hadronic decays
defines beam of Ds on other side of event - Low multiplicity and clean
26 460,000 D- tags!
mbc (GeV)
MM2 (GeV2)
27Paper also includes limits on ?? and e?
So far, so good data agrees well with LQCD for
fD
28Now look for f(Ds)
A little harder best place to run produces DsDs
We call the tag side the Ds- 70514 Ds- events
29Now add the photon, and look at the missing mass
squared to find the events and see the Ds
43,859 reconstructed Ds before we look at any of
its tracks
30Look for occasions when track is
MinIonizing (mostly Ds ???) or more than
MinIonizing (mostly Ds???????)
Overall Fit Blue Ds ??? - Grey Ds??????? -
Purple Non Ds background Red Ds background -
Green
31We find B(Ds ???) 0.565 0.045 0.017 By
this method B(Ds???) 6.42 0.81 0.18 but
there are other methods.Look for Ds???, ?e??
Here the business plot is the extra energy
found in events with a Ds, an e candidate and no
other tracks. B(Ds???) 5.300.470.22
But were not done yet.
32Look for events where Ds???????? ??0?? High
branching fractions high backgrounds.
Total Fit Signal K0??0
33Putting the Ds results together MODE
B()
f(Ds) (MeV) Ds???? ??? 6.42 0.81
0.18 278.0 17.5 4.4 Ds????e??
5.30 0.47 0.22 252.6 11.2
5.6 Ds??????????0?? 5.52 0.57 0.21
257.8 13.3 5.2 Ds ???
0.565 0.045 0.017 257.6 10.3
4.3 assuming the SM f(Ds) 259.0
6.2 3.0 MeV But the lattice
says f(Ds) 241 3 MeV
(HPQCDUKQCD collaboration for lattice) 2.4
standard deviation discrepency remember that
f(D) has very good agreement.
34Another thing that was done with the Ds data
I got interested in an old question can
we find baryonic decays of the Ds only one such
decay possible, Ds ? p n
35Reconstruct on Ds to KK? and other modes,
reconstruct a ? plus a firmly identified proton
(and no other tracks). Look at the missing mass
of the event, and see if It peaks at the
(anti-)neutron mass. (Note that no attempt is
made to reconstruct the (anti-)neutron). Much use
made of kinematic fitting.
PRL 100181802 (2008)
Small, but clean signal corresponding to a
branching fraction of (1.3 0.36)x10-3
This order of magnitude post-dicted by Chan,
Cheng and Hsiao using a model invoking long-distan
ce enhancement of the W-exchange diagram.
This is first and only decay of a charmed meson
into baryons ever observed!
36- CONCLUSIONS
- CLEO has now stopped taking data. It produced 30
years - of physics, and we look forward to several more
years - BES III is now taking over as the premier
charmonium factory. - I showed some recent results
- The hc is now well measured, and shown to decay
directly - to hadrons at a similar rate to the radiative
decays. - 2. The charm decay constants are well-measured.
The D - is in very good agreement with lattice
calculations. The - Ds one is not.
- These are just a few of the many topics still
under investigation - expect many more CLEO talks in years to come.