Study of DS system

1
Study of DS? system

• A. Evdokimov and I. Larin at ITEP (Moscow) are
  doing studies of the charm states decaying with
  photons
• They look in particular at D and DS combinations
  with photons
• Nothing special with D meson yet
• With recent discoveries of DS(2317,2457) there
  are more chance with DS, so

2
Study of DS? look in DS ? ? ?
Mass 2640 MeV Width 15 MeV S/vB 8
s
CUTS
? M(?) 80 MeV, E?gt 3.2GeV,
Combinations/20 MeV
cos(T?) gt-0.9
Peak width compatible
with mass resolution
Mass of DS ?, GeV
3
Study of DS? DS pº
S/vB 3.5 s
Combinations/20 MeV
Mass of DS pº, GeV
4
Study of DS? DS?
S/vB 7 s
Combinations/10 MeV
Mass difference of DS ? and DS, GeV
5
Study of DS? start look at DS
Combinations/10 MeV
Mass, GeV
6
Study of DS? look at pº and ?
Combinations/4 MeV
7
Study of DS? look at ?, pº and ? (no cuts on
? multiplicity!)
pº
? window
E?, GeV
?? mass, GeV
8
Study of DS? improvements, selections, cuts

• New non-linearity tables
• Two versions of analysis give similar results
• recon for neutral particles
• hand made neutrals
• Cuts on ? energies (see plots)
• ?-s from pº window are excluded
• backward angles of ? emission in DS? C.M.S.
  (T?) are excluded
• Constrains on DS, ? and pº masses
• Note about 10 of events have double entries in
  the plots

9
Study of DS?(2640) side-band study
M(KK p)
None
None
None
M(??)
None
None
Signal
None
None
bump?
Detailed study by I. Larin (see appendix)
(DS?-DS)mass
DS mass
10
Study of DS?(2640) peak of ? in ? ?-mass
distribution in DS mass window
S/vB 4s
11
Study of DS?(2640) peak in ?-mass gates
Isotropy
Forward asymmetry
12
Study of DS?(2640) ? angular distribution in
C.M.S
Isotropy
Forward asymmetry
13
Study of DS?(2640) possible influence of
DS(2112)
With DS(2112) window for ?
No DS(2112) window for ?
Combinations/25 MeV
Mass of DS ?, GeV
14
Study of DS?(2640) ? 3p
S/vB 5 s
Combinations/25 MeV
Mass of DS ?, GeV
15
Study of DS?(2640) confirmation from IHEP
analysis
IHEP group using standard SOAP with Photon
calibration tables provided by ITEP reproduced
general features of the DS? peak. These tables
are available upon request. Working on details
16
Study of DS?(2640) ? 3p/ ? ? ?Monte-Carlo
study
Generated 10000 events
Reconstructed Ds Ds
Efficiency Dseta(2630)
(100 Br) eta -gt 3pi 609.5 -37.71
88.35-15.31 14.5-2.5 Dseta(2630) eta -gt
gg 545.3 -30.84 187.9-19.28
34.45-3.53 Ds(2112) 712.1 -35.87
206.7-27.73 28.97-3.89 Dspi0 (2317)
712.1 -35.87 180.1-28.0 25.3-3.93
Reconstructed in the experiment Ds 732.7 -
37.74
17
Study of DS?(2640) ? 3p/ ? ? ?Monte-Carlo
study
DS? 3p/DS ? ? ? (Monte-Carlo)DS? 3p/DS ?
? (Experiment)
.92 -.46
About 60 of DS are coming from DS ? according
Monte-Carlo too much??
18
Study of DS? work in progress

• Strong indication of a new Ds family state,
• BUT much work to do
• Reflections and backgrounds
• Event by event comparisons
• Theory speculations hybrid gluon-quark states,
  radial center mass excitations?
• Any suggestions?