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Two New Resonances in the Strange Charm System. Brian Meadows University of Cincinnati. Outline. Charm meson spectroscopy – brief history. The Discovery of D * sJ (2317) ! D s  0 The second D sJ state Present experimental situation Summary and Discussion. Important Milestones.

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two new resonances in the strange charm system

Two New Resonancesin the Strange Charm System.

Brian Meadows

University of Cincinnati

Brian Meadows, U. Cincinnati.

outline
Outline
  • Charm meson spectroscopy – brief history.
  • The Discovery of D*sJ (2317)! Ds0
  • The second DsJ state
  • Present experimental situation
  • Summary and Discussion

Brian Meadows, U. Cincinnati

important milestones
Important Milestones

1974: J/ observed ! discovery of charm.

1975: Open charm discovered (c, FNAL BC 1975 ; D0, D+, SLAC 1976)

1976: De Rujula, Georgi, Glashow – light and heavy degrees of freedom decouple.

1989: Heavy Quark Symmetry

Brian Meadows, U. Cincinnati

heavy light systems are like the hydrogen atom

SQ

L

Sq

Heavy-Light Systems areLike the Hydrogen Atom
  • When mQ ! 1, sQ is fixed.
  • So jq = L­sq is separately conserved
  • Total spin J = jq­sQ
    • Ground state (L=0) is doublet with jq=1/2
    • Orbital excitations (L>0) – two doublets (jq=l+1/2 and jq=l-1/2).
  • For decays to ground state (L=1)! (L=0) +  :
    • for jq=3/2 state, final hadrons are in orbital D wave

!jq= 3/2 states are narrow.

    • for decay of DJ(jq=1/2) state, final hadrons are in orbital S wave

!jq=1/2 states are expected to be broad.

Brian Meadows, U. Cincinnati

heavy light systems 2
Heavy-Light Systems (2)

2jqLJ

JP

  • Narrow statesare easy to find.
  • Wide states are hard.
  • Since charm quark is not infinitely heavy, some jq=1/2, 3/2 mixing can occur for the JP=1+ states.

jq = 3/2

2+

small

3P2

large

1+

1P1

L = 1

1+

3P1

small

jq = 1/2

1P0

0+

large

tensor

spin-orbit

jq = 1/2

1-

small

1S1

L = 0

small

0-

1S0

Brian Meadows, U. Cincinnati

charmed meson spectroscopy
Charmed Meson Spectroscopy
  • This picture worked well prior to this year with all narrow L=0 and L=1 states found by 1995.
  • The wide, nonstrange jl=1/2 states were found in B decays by CLEO (1999) and BELLE (2002). Subsequently confirmed by BABAR in 2003.
  • Many potential model calculations for masses and widths predicted, mostly correctly, the expected, wide jl=1/2 states
    • Generally agreed that L=1 nonstrange states - 1/2D0,1/2D1 would be above threshold for decay with  emission.
    • And that strange ones 1/2Ds0,1/2Ds1 would be above threshold for K emission.

Brian Meadows, U. Cincinnati

charmed meson spectroscopy c 1995
Charmed Meson Spectroscopy c. 1995

Brian Meadows, U. Cincinnati

charmed meson spectroscopy pre 2003
Charmed Meson Spectroscopy pre 2003

Brian Meadows, U. Cincinnati

the babar detector at slac pep2
The BaBar Detector at SLAC (PEP2)
  • Asymmetric e+e- collisions at (4S).
  •  = 0.56 (3.1 GeV e+, 9.0 GeV e-)
  • Principal purpose – study CPV in B decays

1.5 T superconducting field.

Instrumented Flux Return (IFR)

Resistive Plate Chambers (RPC’s):

Barrel: 19 layers in 65 cm steel

Endcap: 18 “ “ 60 cm “

Brian Meadows, U. Cincinnati

electromagnetic calorimeter
Electromagnetic Calorimeter
  • CsI (doped with Tl) crystals
    • Arranged in 48()£120()
    • » 2.5% gaps in .
  • Forward endcap with 8 more  rings (820 crystals).

BABAR

0

Brian Meadows, U. Cincinnati

particle id dirc

144 quartz bars

Particle ID - DIRC
  • Measures Cherenkov angle in 144 quartz bars arranged as a “barrel”.
  • Photons transported by internal reflection
  • Along the bars themselves.
  • Detected at end by ~ 10,000 PMT’s

Detector of

Internally

Reflected

Cherenkov light

PMT’s

Brian Meadows, U. Cincinnati

drift chamber
Drift Chamber

40 layer small cell design

7104 cells

He-Isobutane for low multiple scattering

dE/dx

Resolution

»7.5%

Mean position

Resolution

125 m

Brian Meadows, U. Cincinnati

silicon vertex tracker svt
Silicon Vertex Tracker (SVT)
  • 5 Layers double sided AC-coupled Silicon
  • Rad-hard readout IC (2 MRad – replace ~2005)
  • Low mass design
  • Stand alone tracking for slow particles
  • Point resolution z» 20 m
  • Radius 32-140 mm

Brian Meadows, U. Cincinnati

pep ii performances

Run 3

Run 4

Run 2

Run 1

Off Peak

PEP-II performances

Peak Luminosity ~ 6 £ 1033 cm-2/ s-1

24 fb-1 in run 1

70 fb-1 in run2

36 fb-1 so far in run3

10 fb-1 so far in run4

This analysis uses runs 1 and 2

» 110 M cc pairs

9% off peak

Currently (Nov 2003)

run 4 is in progress

with ~155 fb-1

Brian Meadows, U. Cincinnati

charm at the b a b ar b factory

On

Off

Charm at the BABARB Factory?
  • Cross section is large Can use “off peak” data
  • Also
    • Relatively small combinatorial backgrounds in e+e- interactions.
    • Good particle ID.
    • Detection of all possible final states including neutrals.
    • Good tracking and vertexing
    • Very high statistics.

Brian Meadows, U. Cincinnati

charm at the b a b ar b factory1
Charm at the BABARB Factory?
  • Present sample of 91 fb-1 sample contains
  • Compare with other charm experiments:
    • E791 - 35,400 1
    • FOCUS - 120,000 2
    • CDF - 56,320
  • Approximately 1.12 £ 106 untagged

D0!K-+ events

1. E791 Collaboration, Phys.Rev.Lett. 83 (1999) 32.

2. Focus Collaboration, Phys.Lett. B485 (2000) 62.

Brian Meadows, U. Cincinnati

data selection
Data Selection
  • All pairs of ’s, each  having energy > 100 MeV, are fitted to a 0 with mass constraint.
  • Each 0 is fitted twice:
    • To the production vertex to investigate the Ds+0 mass.
    • To the K+K-+ vertex so that we can also use the Ds! K+K-+0 mode.

D’s from B decays were removed:

- each event was required to have pD* > 2.5 GeV/c

BABAR results from B decays are forthcoming however.

Brian Meadows, U. Cincinnati

k k mass spectrum
K+K-+ Mass Spectrum

Approx. 131,000 Ds+ events above large background.

4

3

2

1

0

X 103

X 103

60

40

20

0

D0! K+K-

Events / 3 MeV/c2

1.75 1.85 1.95

m(K-K+) GeV/c2

1.8 1.9 2.0

m(K-K++) GeV/c2

Small bump at 2010 MeV/c2 from

Brian Meadows, U. Cincinnati

the d s dalitz plot
The Ds+ Dalitz Plot
  • Data sample: D*s(2112)+!Ds+:
  • NOTE
    • K* and  bands do not cross (no double counting).
    • cos2 distributions evident in vector bands.

Selection essentially keeps events in the 4 peaks.

Brian Meadows, U. Cincinnati

total k k mass spectrum
Total K+K-+ Mass Spectrum
  • Sum of + and K¤0K+ contributions is » 80,000 Ds+ above background.
  • We define

signal region:

1954 < m(K+K-+) < 1980 MeV/c2

and two sideband regions:

1912 < m(K+K-+) < 1934 MeV/c2

1998 < m(K+K-+) < 2020 MeV/c2

Brian Meadows, U. Cincinnati

the d s 2317 see prl 90 242001 2003
The Ds(2317)see PRL 90, 242001 (2003)
  • When Antimo Palano studied the Ds0 system he found a huge, unexpected peak.

CLEO

There is no signal from Ds+ sidebands.

The Ds*!Ds+0 signal is clear too.

How did CLEO miss it?!

Brian Meadows, U. Cincinnati

the d s 2317
The Ds(2317)
  • The signal is clearly associated with both Ds+ and 0.

There is no signal from 0 sidebands either.

[NOTE – smearing the 0 signal smears the Ds*! Ds+0 signal too.]

Brian Meadows, U. Cincinnati

a real particle
A Real Particle?
  • Is the signal due to reflection of a known resonance?

Approximately 80 £ 106e+e-!cc reactions simulated.

All that was known about charm spectroscopy was included.

Conclude signal is not a reflection.

Brian Meadows, U. Cincinnati

cms momentum p dependence
CMS Momentum (p*) Dependence
  • Signal seen in all p* ranges.
  • Background less significant at higher p* values
  • Yield maximum at ~3.9 GeV/c
  • Excitation curve appears to be compatible with charm fragmentation process.

Brian Meadows, U. Cincinnati

multiple d s modes

250

200

150

100

50

0

200

150

100

50

0

K*

Events / 5 MeV/c2

2.1 2.3 2.5

2.1 2.3 2.5

m(Ds+0)GeV/c2

Multiple Ds+ Modes
  • Separate + and K¤0K+ subsamples:
  • Ds*+(2112) and signal at 2.317 GeV/c2 present in both channels with roughly equal strength.

p* > 3.5 GeV/c

Brian Meadows, U. Cincinnati

fit to the signal

400

300

200

100

0

Events / 5 MeV/c2

2.1 2.2 2.3 2.4 2.5

m(Ds+0) GeV/c2

Fit to the Signal

Require p* > 3.5 GeV/c

Fit to polynomial and a single Gaussian.

N = 1267 § 53 Events

m = 2316.8 § 0.4 GeV/c2 = 8.6 § 0.4 MeV/c2

(errors statistical only).

 is compatible with detector resolution.

m requires small correction due to Ds(2458) overlap.

Brian Meadows, U. Cincinnati

cross check a different topology
Cross Check - a Different Topology

Select Ds+! K-K++0

N = 273 § 33 events

m = 2317.6 § 1.3 MeV/c2

 = 8.8 § 1.1 MeV/c2

(consistent with detector resolution).

Results agree with those from other Ds+ modes

Brian Meadows, U. Cincinnati

conclusions on the state so far
Conclusions on the state so far
  • Real and it decays to Ds+0: Implies natural parity.
  • Narrow - consistent with BaBar resolution : < 10MeV/c2.
  • If a normal Ds+ then this decay violates I spin conservation.
    • This could explain the narrowness.
    • Being below D0K+ threshold may force such a decay.
  • Could be the missing 0+ BUT if so, its mass is lower by » 170 MeV/c2 than expected by potential models.

We label it “DsJ*(2317)+”

  • What else …

Brian Meadows, U. Cincinnati

d sj 2317 decay angular distribution
DsJ+(2317) Decay Angular Distribution
  • Helicity angle distribution could provide spin information.
  • The corrected distribution in cos  is consistent with being flat (43% probability).
  • This could mean that J=0 or just that state is unaligned.

Acceptance

Uncorrected

Corrected

0

DsJ(2317)

10 x Efficiency

Ds

cos

cos

cos

Brian Meadows, U. Cincinnati

search for other d sj 2317 decay modes
Search for Other DsJ+(2317) Decay Modes
  • We have studied the mass spectra for
    • Ds+0 0
    • Ds+
    • Ds+ 
    • Ds*+(2112)
    • Ds+0 
  • In all cases, we require that:
    • The ’s are not part of any 0 candidate.
    • The combination has p* > 3.5 GeV/c.

None of these found

Brian Meadows, U. Cincinnati

d s d s d s 2112
Ds+, Ds+, Ds*(2112)
  • No evidence for DsJ(2317) in any of these decays.
    • Absence of Ds+ weakly suggests J = 0
    • However other two modes would be expected for a JP = 0+.

Brian Meadows, U. Cincinnati

d s 0 d s 2112 0 other possibilities
Ds+0, Ds*(2112)0- Other Possibilities
  • No evidence for D*sJ(2317)+ either of these modes
  • BUT …
    • Is there a second state at ~ 2460 MeV/c2 ?

Events / 7 MeV/c2

Ds*(2112)0

m(Ds+0)

Brian Meadows, U. Cincinnati

a second state

2.4

2.3

2.2

2.1

2.0

m(Ds+)GeV/c2

2.1 2.2 2.3 2.4 2.5

m (Ds+0) GeV/c2

A Second State ?
  • The decays

DsJ(2317)+!Ds+0 and Ds*(2112)+!Ds+

overlap kinematically just where m(Ds+0)~2460 MeV/c2.

  • Gives us two problems:
    • Produces a kinematic peak at 2460 MeV/c2 – signal?
    • Resolution smearing makes it difficult to distinguish decays of a 2460 MeV/c2 state to Ds*(2112)+0 or D*sJ(2317)+ ?

m(Ds+0)=

2.46 GeV/c2

Brian Meadows, U. Cincinnati

a second state1
A Second State ?
  • Another concern we resolved: Is the D*sJ(2317) signal just a reflection of the higher mass state?!
  • NO – such reflection is
    • Too wide
    • Wrong mass
    • Too small by factor ~ 5.

Brian Meadows, U. Cincinnati

a second state2
A Second State ?

… from our PRL 90 (2003) 242001.

  • “Although we rule out the decay of a state of mass 2.46 GeV/c2 as the sole source of the Ds+0 mass peak corresponding to the D*sJ(2317)+, such a state may be produced in addition to the D*sJ(2317)+. However, the complexity of the overlapping kinematics of the Ds*(2112)+!Ds+ and D*sJ(2317)+!Ds+0 decays requires more detailed study, currently underway, in order to arrive at a definitive conclusion.”

Meanwhile …

Brian Meadows, U. Cincinnati

cleo sees d sj 2317 too
CLEO Sees D*sJ(2317) Too

m(Ds0) – m(Ds)

350.0 § 1.2 (stat) § 1.0 (syst) (MeV/c2)

Not in Ds+-

  • From 13.5 fb-1 CLEO II
    • Signal seen in Ds0
    • Not seen in Ds+-,
    • Ds, Ds1(2112)

Signal has events (» same yield / fb-1 as BABAR).

PRD 68, 032002 (2003)

Brian Meadows, U. Cincinnati

so does belle in continuum
So Does Belle (in continuum)
  • 78 fb-1 sample
  • Ds!, p* > 3.5 GeV/c
  • M = 2317 § 0.5 MeV/c2
  • = 8.1 § 0.5 MeV/c2
  • N = 770 § 43 events
  • They also observe it in
  • B!D DsJ decays.

Y. Mikami, et al, hep-ex/0307052v2 (2003)

Brian Meadows, U. Cincinnati

the d sj 2458
The DsJ (2458)+
  • CLEO results are published with title:

“Observation of a Narrow Resonance of Mass 2.46-GeV/c2 Decaying to Ds*(2112)+0 and Confirmation of the D*sJ(2317)+ State.”

in PRD 68, 032002 (2003)

  • BELLE has also observed the DsJ (2458)+
    • In continuum – hep-ex/0307052
    • In B!DDsJ decay – hep-ex/0308019
  • What BABAR says about the second state now …

Brian Meadows, U. Cincinnati

recap the problem

2.4

2.3

2.2

2.1

2.0

m(Ds+)GeV/c2

2.1 2.2 2.3 2.4 2.5

m (Ds+0) GeV/c2

Recap - theProblem
  • The decays

DsJ(2317)+!Ds+0 and Ds*(2112)+!Ds+

overlap just where m(Ds+0)~2460 MeV/c2.

  • This gives us two problems:
    • Produces a kinematic peak at 2460 MeV/c2
    • Resolution smearing makes it difficult to distinguish decays of a 2460 MeV/c2 state to Ds*(2112)+0 or DsJ(2317)+

m(Ds+0)=

2.46 GeV/c2

Brian Meadows, U. Cincinnati

b a b ar there is a signal
BABAR - There is a Signal!

Data

MC

A strong peak appears in BABAR data that is absent in generic MC

[e+e-!cc that includes D*sJ(2317)+ production].

Attribute the excess to a new signal at 2458 MeV/c2.

DsJ(2458)+

m() ´ m(KK0) - m(KK0)

m(0) ´ m(KK0) - m(KK)

NOTE – Change of variables

Next: a) extract signal strength and properties; b) distinguish Ds*(2112)+0 from DsJ(2317)+

Brian Meadows, U. Cincinnati

extraction of signal from background

100

80

60

40

20

0

0.3

0.2

0.1

80

60

40

20

0

Events / 7 MeV/c2

m() GeV/c2

0.25 0.50

m(0) GeV/c2

0.25 0.50

m(0) GeV/c2

0.25 0.50

m(0) GeV/c2

Extraction of Signal from Background

Seems most obvious method - make a (peaking) sideband subtraction and fit to Gaussian: ! m = 344.6 § 1.2 MeV/c2.

BUT:

  • Assumes background is linear.
  • Not true as resolution of m(0) changes with m().
    • Width of signal depends on width of sideband selected.
  • Ignores D*sJ(2317)+ decay possibility.

Brian Meadows, U. Cincinnati

decay mode

Monte Carlo for

DsJ(2458)+!Ds*(2112)0

Monte Carlo for

DsJ(2458)+!DsJ(2317)

Decay Mode
  • Distinction between Ds*(2112)0 and DsJ (2317)+ decays is possible from different line shapes each produces.
  • Data clearly prefer the shape for DsJ (2458)+! Ds*(2112)0

Brian Meadows, U. Cincinnati

channel likelihood 1 method
Channel Likelihood1 Method
  • Determine fractions xi of processes producing events and best mass (m) and Gaussian width () for DsJ (2458).
  • Each Ds+0 combination is assigned a likelihood:

L = x1P1 + x2P2 + … + (1 - x1 - x2 - …)

where Pi are normalized Probability Density Functions.

Processes included were:

P1: DsJ(2458) !Ds*0

P2: DsJ(2458) !DsJ(2317)

P3: Ds+0!Ds* + random 

P4: Ds+0!DsJ(2317) + random 0

P5: Ds+0! combinatorial background

Assumption: that DsJ(2458) decay is all quasi two body with no interference (reasonable since the states are all narrow).

1 P.E. Condon and P.L. Powell, PRD 9, 2558 (1974)

Brian Meadows, U. Cincinnati

fit results
Fit Results
  • Important results from the fit are:
  • The DsJ(2458)+ width is consistent with detector resolution indicating that the state is narrow.
  • We infer that:

Brian Meadows, U. Cincinnati

fit results 2
Fit Results (2)
  • The fit assigns a probability xiPi to each event to belong to a process, so weighted plots take account of all reflections.

Unweighted

Ds+0

Weighted

Data

Weighted

DsJ(2458)+!Ds*+0

Fit

Weighted

DsJ(2458)+!DsJ(2317)+

Brian Meadows, U. Cincinnati

correction to d sj 2317 mass
Correction to DsJ (2317)+ Mass
  • Distortion of the DsJ(2317)+ signal due to background from DsJ(2458)+!Ds*(2112)+0decays can be estimated from a Monte Carlo study.
  • Re fitting to include this, DsJ(2317)+ parameters are:

m = 2317.3 § 0.4 MeV/c2 ;  = 7.3 § 0.2 MeV/c2.

Brian Meadows, U. Cincinnati

spin parity of d sj 2458
Spin-Parity of DsJ(2458)+
  • The decay observed here violates I-spin. The width is small.
  • So natural parity (0+, 1-, 2+, …) appear to be ruled out as this state could decay to D0K+, conserving I-spin.
  • It is below D*K threshold, a decay accessible to unnatural parity, so its width is compatible with JP=0-, 1+, 2-, …
  • The helicity distribution is also consistent with this hypothesis.

Brian Meadows, U. Cincinnati

spin parity of d sj 24581
Spin-Parity of DsJ (2458)+
  • Helicity angle of :
  • JP = 0- agrees worst. 1- and 2+ cannot be ruled out.
  • Unnatural parity distributions depend on alignment of DsJ(2458)+.

Ds*(2112)

h

0

Ds

No conclusive information on spin here

Brian Meadows, U. Cincinnati

cleo and belle see d s 2458 in continuum

Belle 86.9 fb-1

CLEO “Ds(2463)” 13.5 fb-1

D*(2112)

D*(2112)

sidebands

N = 41§ 12 events (>5)

m = 349.8 § 1.3 MeV/c2

N = 126§ 25 events

m = 345.4 § 1.3 MeV/c2

CLEO and Belle See Ds(2458) in Continuum

PRD 68, 032002 (2003)

hep-ex/0307052

Brian Meadows, U. Cincinnati

more observations by belle
More Observations by Belle
  • See both states in B decay
  • See DsJ(2458)+!Ds+

Continuum

B!D DsJ

DsJ(2317)+

!Ds+0

DsJ(2458)+

!Ds*(2112)+0

DsJ(2458)+ !Ds+

Rules out J = 0

Brian Meadows, U. Cincinnati

belle observes d sj 2458 d s
Belle observes DsJ(2458)+!Ds+
  • Helicity angle from Ds+ decay in:
  • NOTE – DsJ(2458)+ is aligned with helicity 0.
    • J=1 appears to be better description than J=2.

J = 2

J = 1

! JP = 1+ strongly suggested by all evidence so far.

Brian Meadows, U. Cincinnati

decays to di pions
Decays to Di-pions

Belle – 86.9 fb-1

See DsJ (2458) !Ds+-

Modes conserve I-spin

But are OZI suppressed

Preliminary

CDF Run 2

~ 80 pb-1

CLEO II

~13.5 fb-1

CLEO 13.5 fb-1

m(Ds++-)

Brian Meadows, U. Cincinnati

comparison of results
Comparison of Results
  • BABAR measures, for p* > 3.5 GeV/c2, the ratio
  • This, and masses for the two DsJ states, are in good agreement with Belle. Values for CLEO’s DsJ (2458)+ mass and R are slightly higher.

Brian Meadows, U. Cincinnati

experimental summary d sj 2317
Experimental Summary - DsJ*(2317)+
  • A large, narrow state at 2.32 GeV/c2 with width  < 10 MeV/c2 was discovered by BABAR.
  • The mass is about 40 MeV/c2 below the DK threshold.

m = 2317.4 § 0.5 (stat.) § 0.6 (syst.) MeV/c2 (my average)

  • So far, this is only seen in the Ds0 decay mode. It is not seen in Ds , Ds, Ds, Ds*(2112), Ds or Ds0
  • The decay to Ds0 implies natural parity (0+, 1-, 2+, etc.)
  • J P=0+ suggested by absence of Ds+  or Ds decays.
  • If this is so, decay to Ds*(2112)  is allowed, but not yet seen.
  • The state is confirmed by both CLEO and BELLE.

Brian Meadows, U. Cincinnati

experimental summary d sj 2458
Experimental Summary - DsJ (2458)+
  • BABAR first showed evidence for a narrow structure in the Ds*(2112)0 system near 2460 MeV/c2, however they deferred claiming it as a well defined state.
  • CLEO observes DsJ (2463) ! Ds* (2112)0 state, confirmed by BELLE in continuum and B decay.
  • Belle also observe decay to Ds and Ds+-.
  • The mass is about 40 MeV/c2 below the D*K but above D0K+ threshold.

m = 2458.6 § 0.8 (stat.) § 0.7 (syst.) (my average)

  • J P=1+ suggested by absence of a signal in D0 K+, and in helicity distribution from B decay sample. Higher spins are not excluded.

Brian Meadows, U. Cincinnati

charmed meson spectroscopy now
Charmed Meson Spectroscopy Now

John Bartelt, Sept, 2003

Brian Meadows, U. Cincinnati

if these states are cs mesons
If these States are cs Mesons.
  • Decays observed violate isospin conservation
    • Not a problem. D*s(2112) also decays to Ds0 about 5% of the time. Rate predicted by Cho and Wise assuming 0- mixing is the mechanism.
    • But can we learn anything from relative rates for 0 vs. ?
  • A class of potential models is incapable of predicting their masses to be so low.
    • Earlier predictions good to ~10 MeV/c2 . New states ~160-180 MeV/c2 low.

R. Cahn and J.D. Jackson, hep-ph/0305012, P. Colangelo and F. De Fazio, hep-ph/0305140, S. Godfrey, hep-ph/0305012.

    • Apparently relativistic corrections do not help either.

W. Lucha and F. F. Schoberl, hep-ph/0309341

  • Possibly, if effects are due to mixing of the jq=1/2 and 3/2 states, then B spectroscopy will reveal this?

Brian Meadows, U. Cincinnati

if these states are cs mesons1
If these States are cs Mesons.
  • Quenched lattice gauge calculations also predict higher masses for a scalar cs system.

G. Bali, hep-ph/0305209

  • However, chiral symmetry models predict the observed splittings

m1+ – m0+ = m1- – m0- ¼ 141.2 § 1.2

W. A. Bardeen, E. J. Eichten, C. T. Hill, hep-ph/0305049

Brian Meadows, U. Cincinnati

what else can they be
What Else Can they Be?
  • Meson-meson molecules (conjectured by N. Isgur and H. Lipkin), or 4q states
    • If so we still need to find the cs states.
    • Expect to find other states with mixed I spin.
    • Should see narrow Ds+§ decay modes.

T. Barnes, F. E. Close, H. J. Lipkin, hep-ph/0305025, Cheng and Hou, hep-ph/0305038, S. Szczepaniac, hep-ph/0305060, K. Terasaki, hep-ph/0305213.

  • Mixed 4 quark and cs systems
    • These states are the predominantly cs part
    • Need to find mainly 4q component - at higher mass (~2.6 GeV/c2) and broad.

T. E. Browder, S. Pakvasa, A. Petrov, hep-ph/0307054 v4

  • Poles in unitarized DK scattering

E. Van Beveran, G. Rupp, hep-ph/0305035, hep-ph/0306155

Brian Meadows, U. Cincinnati

summary
Summary
  • Discovery by BABAR of the D*sJ(2317)+ has opened up a new window in QCD.
  • This could have far reaching consequences for studies of spectroscopy in all sectors.
  • Much theoretical speculation (at least 40 papers so far)
  • Much experimental work to do to look for radiative decays and more new states , perhaps exotics.

Brian Meadows, U. Cincinnati

yet another new narrow state
Yet Another New Narrow State!

BELLE’s “X”

CDF Confirms “X”

BELLE : m = 3872.0 § 0.6 § 0.5 MeV/c2

CDF : m = 3871.4 § 0.7 (stat.) MeV/c2

 compatible with resolution.

Brian Meadows, U. Cincinnati

pure speculation
Pure Speculation ?
  • Could there be a relationship between
  • Meson-meson (DD*) molecules ?

and

?

Brian Meadows, U. Cincinnati

slide63

Back up Slides

Brian Meadows, U. Cincinnati

peaking background
Peaking Background

CLEO background – judged from the Ds*(2112)+ sidebands - has only a small peak.

CLEO

Belle

BABAR

Peak

  • Peak is below DsJ(2458)+ signal
  • For BaBar and Belle it is aboveDsJ(2458)+.

Brian Meadows, U. Cincinnati

other results from belle
Other Results from BELLE:

Brian Meadows, U. Cincinnati

particle id dirc1
Particle ID - DIRC

It Works Beautifully!

10

8

6

4

2

0

BABAR

K/ separation ()

Provides excellent K/ separation

over the whole kinematic range

  • 2.5 3 3.5 4
  • Momentum (GeV/c)

Brian Meadows, U. Cincinnati

particle id dirc2
Particle ID - DIRC

D0

D0

Brian Meadows, U. Cincinnati

an example d s production spectrum
An Example: Ds Production spectrum
  • Below 2.4 GeV/c Ds can come from B decay
  • Can use off peak data there to reduce combinatorial background

Off peak (normalized for p*>2.4 GeV/c)

On peak

Brian Meadows, U. Cincinnati

selection of d s and k 0 k
Selection of Ds+!+ and K¤0K+
  • Select  mass band: |m(K+K-) – 1.019| · 0.01 GeV/c2;
  • Select K¤0 mass band: |m(+K-) – 0.896| · 0.05 GeV/c2;
  • Require |cos| > 0.5 to enhance proper helicities of each vector.
  • Each resulting sample has about same size.

Brian Meadows, U. Cincinnati

summary1
Summary
  • New charmed, strange, narrow resonance at 2.32 GeV/c.
  • Poses possible problems for the quark potential model.
  • May be a four quark or DK bound state.
  • Much speculation is being generated:

R. Cahn, J.D. Jackson, hep-ph/0305012

T. Barnes, F. E. Close, H. J. Lipkin, hep-ph/0305025

E. Van Beveran, G. Rupp, hep-ph/0305035

H-Y Cheng, W-S Hou, hep-ph/0305038

W. A. Bardeen, E. J. Eichten, C. T. Hill, hep-ph 0305049

P. Szczepaniak, hep-ph/0305060

S. Godfrey, hep-ph/0305122

P. Colangelo, F. De Fazio, hep-ph/0305140

cs

DK

DK

csnn

cs (chiral L)

Dpi

?

?

Brian Meadows, U. Cincinnati

decays to di pions1
Decays to di-Pions

Modes conserve I-spin

But are OZI suppressed

No obvious signals (yet)

BABAR

~81 fb-1

CDF Run II

Preliminary ~80 pb-1

m(Ds+00)

CLEO II

~13.5 fb-1

m(Ds++-)

m(Ds++-) – m(Ds+)

Brian Meadows, U. Cincinnati

dk molecule
DK Molecule?

T. Barnes, F.E. Close, H.J. Lipkin, hep-ph/0305025

  • I=0 csnn or a DK bound state?
  • If DK bound state, then some I=0 component to explain narrow width.

Brian Meadows, U. Cincinnati

a qqcs four quark state
A qqcs Four Quark State?

From H. Cheng and W. Hou, hep-ph/0305038.

Brian Meadows, U. Cincinnati

quasi bound cs state
Quasi Bound cs State?

E. van Beveren, G. Rupp, hep-ph/0305035

  • Charmed cousin of a0(980), f0(980), (600), (800) nonet.
    • Predicts D0(2030) – broad because above DK threshold
    • Also predicts D0(2640), D0(2790) to go with K0(1430), etc.

Brian Meadows, U. Cincinnati

introduction
Introduction

The spectrum of Ds (cs) states has gaps.

  • The scalar state predicted could decay to DK so it would be broad (» 270-990 MeV/c2).

Observed

Predicted

Ds2

Ds1

D*K

Mass GeV

D0K

D*s

DsJ(2317)

Ds

New State

JP

This would make it difficult to observe …BUT

If it were below DK threshold, it could be narrow.

Brian Meadows, U. Cincinnati

data selection1
Data Selection
  • In this study we look for resonances decaying to: Ds0
  • Ds+ mesons are selected with +,K¤0K+ and K+K-+0 decay modes, so we select events in final state:

K+K-+ (+ charged conjugate)

  • To do this we:
    • Select all combinations of three charged tracks with total charge § 1, an identified K+K- pair and a third track which is not a K§.
    • Require Ds+ candidate fit well to a common vertex.
    • Fit the Ds+ composite momentum to a primary vertex

Brian Meadows, U. Cincinnati

resolution improvement
Resolution Improvement

a) Constrain Ds mass

b) Remove duplicated ’s

Brian Meadows, U. Cincinnati

experimental resolution
Experimental Resolution
  • Fit Ds*+(2112) width in Monte Carlo and Data:

Data:  = 6.6 § 0.1 MeV/c2

MC:  = 5.7 § 0.1 MeV/c2

  • So MC is too optimistic by factor 1.16.
  • Generate Monte Carlo events for DsJ+(2317) with  = 0:

 = 7.7 § 0.2 MeV/c2

  • Scale by factor 1.16 ! expect  = 8.9 MeV/c2.
  • ForDsJ+(2317)with p* > 3.0 GeV/c we find:

 =9.0§0.4MeV/c2

So width is consistent with mass resolution.

Brian Meadows, U. Cincinnati

another topology d s k k 0
Another Topology Ds+!K+K-+0

Rational:

  • Mode has same topology as Ds+0 when Ds+!K+K-+.
  • Width of Ds+!K+K-+0 gives further, direct information on the Ds+0 mass resolution.
  • Can provide corroborative evidence for Ds+0(2317) signal.

Strategy:

  • Use other vertex fit.
  • Select cleaner sample using K*0, K*§, +,  resonant sub channel selections.

Brian Meadows, U. Cincinnati

data from d s k k 0
Data from Ds+!K+K-+0

X 103

Use other vertex for 0

Require at least one vector meson in two body subsystem.

No  from a 0 candidate can be part of any other 0.

Require p* > 3.5 GeV/c.

Require laboratory momentum of each  be > 300 MeV/c.

25

20

15

10

5

0

Ds+

D+

1.75 2.0

m(K+K-+0) GeV/c2

Brian Meadows, U. Cincinnati

new narrow resonance d sj 2317
Over 1500 events in the signal.

The resonance has width comparable with the mass resolution in these systems.

It is evident in two different topologies

a)D§s!K§ K¨ § (two modes)

b) D§s!K§ K¨ §0

Masses consistent in all channels – width » resolution.

New Narrow Resonance “DsJ(2317)”

“Ds(2317)”

Ds1(2112)

p* > 3.5 GeV/c

p* > 3.5 GeV/c

Ds1(2112)

Brian Meadows, U. Cincinnati

test using monte carlo simulation
Test Using Monte Carlo Simulation
  • We simulate the reaction

e+e-!cc

using GEANT4.

  • Events generated contain all that is presently known about charm spectroscopy.
  • Approximately 80 x 106 events are processed exactly the same way as the data.

Brian Meadows, U. Cincinnati

test using monte carlo simulation1
Test Using Monte Carlo Simulation
  • Sum of + and K¤0K+ and Ds+0 mass spectra.
    • We observe the known decay: Ds¤+(2112)!Ds+0.
    • The Ds+0 mass spectrum shows no sign of 2.32 GeV/c2 signal. We would expect » 1,400 events.

We conclude that the 2.32 GeV/c2 structure is not due to reflections from known charm states.

Brian Meadows, U. Cincinnati

is 2 32 gev c 2 structure due to d s 2112

2.32 GeV/c2

Is 2.32 GeV/c2 Structure due to Ds¤+(2112)?
  • We use the ’s from the 0 candidate to compute the two masses Ds+1,2.
  • The 2.32 GeV/c2 signal survives when events with a Ds+1,2 mass in the Ds¤+(2112) are removed.

Ds¤+(2112)

removed

Ds¤+(2112)

selected

We conclude that the signal at 2.32 GeV/c2 is not a Ds¤+ reflection

Brian Meadows, U. Cincinnati

mass and width
Mass and Width

Ds+! K-K++0:

M = 2317.6 § 1.3 MeV/c2

 = 8.8 § 1.1 MeV/c2

Ds+! K*0K+, +:

M = 2316.8 § 0.4 MeV/c2

 = 8.6 § 0.4 MeV/c2

Brian Meadows, U. Cincinnati