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Daniel Sherwood 03/2005 Exotic States (Open) Exotic States Hadrons with Exotic Quantum Numbers (Q, S, I) OR Hadrons with Exotic Combinations of Quantum Numbers (J PC ) Unexplained by qq or qqq quark structures Crypto-Exotic States Hadrons With Hidden Exotic Properties –Ordinary Quantum Numbers (Q, S, I, J PC ) –Anomalously Small Widths, Anomalous Decay Channels, Special Production Mechanisms
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Daniel Sherwood
03/2005
Search for Crypto-Exotic States in Babar
Daniel SherwoodDr. Liliana Teodorescu
Daniel Sherwood
03/2005
Outline
• Introduction– Exotic States– Existing Measurements
• Search in Babar– Analysis Strategy– Status of the Analysis
• Conclusions
Daniel Sherwood
03/2005
Exotic States(Open) Exotic States• Hadrons with Exotic Quantum Numbers (Q, S, I)OR• Hadrons with Exotic Combinations of Quantum Numbers
(JPC)
• Unexplained by qq or qqq quark structures
Crypto-Exotic States• Hadrons With Hidden Exotic Properties
– Ordinary Quantum Numbers (Q, S, I, JPC) – Anomalously Small Widths, Anomalous Decay Channels,
Special Production Mechanisms
Daniel Sherwood
03/2005
Existing Measurements
Θ+(1540) – CLAS Ξ--(1842) – NA49 ΘC(3100) – H1
Exotic StatesMesons
Crypto-Exotic StatesMesons
DESY 04-038
R(3520) – CERNPL B 281 (1991) 148
PRL 91,012002 (2003) PL B572 127 (2003)
PL B 89 (1979) 125
R(3170) – CERNBaryons
Baryons
X(3872) – cqcq BELLE
X(3940) – cqcq BELLE
a+ – susd
a0 – 1/√2(susu – sdsd)
a- – sdsu
f0 – 1/√2(susu + sdsd)
σ0 – udud
…
ududcdsdsuududd
Daniel Sherwood
03/2005
Crypto-Exotic Baryons
PL B 89 (1979) 125
R(3170) – CERN
R(3520) – CERNPL B 281 (1991) 148
CERN 2m HBC (8.25 GeV/c)
Argonne 12ft HBC (6.5 GeV/c)
K- + p+ → π- + R
ΓR = 20 MeV
R(3170) → Σ K K + pions
→ Λ K K + pions
→ Ξ K + pions
qqsss
CERN 2m HBC (16Gev/c)
(p+ K+ Ks π- π-) System
MR = 3520 3 MeV/c2
R = 7-7+20 MeV/c2
Decays through K*-
uudcc
Daniel Sherwood
03/2005
Search for R(3520) at Babar
Present Analysis• • Possible Extensions • • Similar + Baryon in Final State• Similar + Baryon and cc in Final State
(Assuming Resonance with Hidden Charm)
XKKpee 0**
XKpKee *XKpKee S 0
Daniel Sherwood
03/2005
Babar Experiment• e+ e- Interaction 10.6GeV
• SVT – Silicon Vertex Tracker – Vertexing and Tracking
• DCH – Drift Chamber - Tracking• EMC – Electromagnetic
Calorimeter -measures particles energy
• DIRC – Detector of Internally Reflected Cherenkov Light – Particle Identification
• IFR – Instumented Flux Return – muon and neutral hadron detection
• Superconducting Solenoid (1.5T Magnetic Field)
• 244 fb-1 Data Recorded
Daniel Sherwood
03/2005
Event Selection (Preliminary)
K*-→KS π-
•Vertexed Using Cascade•Geometric Constraints•RXY < 0.6 cm•|RZ| < 3.2 cm•P(Χ2) < 0.001•DOCA < 0.6 cm
KS →π+π-
•Vertexed Using TreeFitter•Geometric Constraints•Unfitted Mass Window 0.3-0.8•RXY < 0.6 cm•|RZ| < 3.2 cm•P(Χ2) < 0.001•DOCA < 0.6 cm•Signed Flight Length > 0 cm•Flight Significance > 3•Final Mass Window PDG ±10MeV•Mass Constraint
π-•Charged Tracks
π+
•Charged Tracks
π-
•piLHLoose•RXY < 0.6 cm•|RZ| < 3.2 cm
p+
•pLHTight•RXY < 0.6cm•|RZ| < 3.2cm
K+
•KLHTight•RXY < 0.6cm•|RZ| < 3.2cm
π-
•piLHLoose•RXY < 0.6cm•|RZ| < 3.2cm
K*+ π- p+ K+
•Missing Mass Spectrum
KS π- π- p+ K+
•Missing Mass Spectrumπ-•piLHLoose
Daniel Sherwood
03/2005
Selection Criteria•
• Interaction Region– RZ — Half Length of Cylinder (3.2 cm)– RXY — Radius of Cylinder (0.6 cm)
• Daughters Originate from Same Decay– DOCA between Daughters’ Tracks < 0.6cm
• Signed Flight Length (> 0)– Removes Candidates With Unphysical
Decay Lengths
Dunwoodie and Coleman
(DOCA)
Selector Criteria
p+ pLHTight L(p)/L(K) > 5.0L(p)/L(pi) > 0.75If p>0.75 reject electrons
K+ KLHTight L(K)/L(pi) > 0.9L(K)/L(p) > 0.2if p>0.4 reject electrons
Daniel Sherwood
03/2005
KS Reconstruction
Cuts Purity (%)
Initial 75
Final 92
Initial Selection• Two Charged Tracks with Pion
Mass Associated• Kalman Filter Based Vertexer • Geometric Fit Constraints• P(χ2) of the Fit > 0.001• Flight Significance (cτ/σ) > 3• Final Mass Window ±10MeV
around the PDG KS Mass
Final Selection• DOCAππ < 0.6 cm
• |cosθHelicity| < 0.8 (Removes Λs )• |RZ| < 3.2 cm
• RXY < 0.6 cm • Signed Flight Length > 0 cm
Daniel Sherwood
03/2005
(KS K+ p+ π- π-) Missing Mass Spectrum
Daniel Sherwood
03/2005
K*- Reconstruction
Initial Selection• KS and π- Selected as Described
Previously• Geometric Fit Constraints• Newton-Raphson based Vertexer• Mass Window PDG±76 MeV/c2
Final Selection• P(χ2) of the Fit > 0.001• DOCAKsπ < 0.6 cm
• |RZ| < 3.2 cm
• RXY < 0.6 cm Cuts Purity (%)
Initial 6
Final 11
Daniel Sherwood
03/2005
(K*- K+ p+ π-) Missing Mass Spectrum
Daniel Sherwood
03/2005
Conclusions
• Start of This Analysis• Key Points
– KS Reconstruction – Very Good– K*- Reconstruction – Promising– Additional Studies on Data and Monte-Carlo