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