# Presentation: 867771

## Pentaquark Results from CDF 

**International Workshop Pentaquark04  **
**21-Jul, 2004**
**Ming-Jer Wang ( Institute of Physics, Academia Sinica ), **
- Y.S. Chung, F. Curbis,  E. Gerchtein, D. Litvintsev,
- M. Neubauer,  R. Oldeman,
- J. Russ, F. Wurthwein
**For the CDF collaboration  **

- PENTAQUARK04,  Ming-Jer Wang

## Outline

**Motivations**
**CDF Detector**
**Search Strategy**
******c****0** ( **uuddc**** **) **Search**
******+**** ****(**** ****uudds**** ****)**** Search**
**•  ********   ****( qsqsq ) Search**
**Ongoing Searches**
**Summary & Outlook **

- PENTAQUARK04,  Ming-Jer Wang

## Motivation for Pentaquark Search 

*5 quark state **predicted* *by*
*Diakonov, Petrov, Polyakov(1997)*:
- 4 quarks + 1 antiquark
- Q+ : u u d d s(bar)
- Mass  ~ 1530 MeV/c2
- Width ~ 15 MeV/c2
- Decays equally to nK+ and pK0

- 10 experiments report evidence
-   3 experiments report no observation
*                           **(HERA-B, PHENIX, BES)*

- PENTAQUARK04,  Ming-Jer Wang

## Motivation for forming a PQ Task Force

**• ****H1 claimed to have found a peak and interpreted it as the ****Θ****c****( 3099 ) state**
**   ****-looked into the D*p decay channel**
**   ****-a narrow resonance in D*p mass   combination is observed**
**   ****-mass of 3099+/-3(stat.)+/-5(syst.) MeV**
**   ****-a measured Gaussian width of 12+/-3 (stat.) MeV**
** ****• ****A CDF pentaquark task force was formed to do comprehensive pentaquark states search after 4 simultaneous search**
**	****presentations by Y.S. Chung, K. Rinnert, Ming-Jer Wang, D. Litvintsev of this state on 15-Mar-2004 at the B hadronic meeting**
**• ****Two searches have been performed by E.Gerchtein, D. Litvintsev, F. Curbis, and R. Oldeman before this CDF task force was formed**

- PENTAQUARK04,  Ming-Jer Wang

## Pentaquark Searches with CDF Detector

**Search Mode****s:**
- c0
-      ↳ D*+p(bar)
-           ↳ D0+
-                ↳ K−+
- + → Ks0p
- 		     ↳ +  −
- •    ̅ ̅
-     ↳  ̅  ̅
-           ↳ Λ  ̅
-                ↳ − p

- large radius
- tracking wire
- chamber (COT)

- silicon vertex
- detector (SVX)

- time of flight
- (TOF)

- PENTAQUARK04,  Ming-Jer Wang

## Unknown factors about Pentaquarks @ pp  Collider & sqrt(s) = 1.96 TeV:
       - Production cross section? -> Which PQ is the best to look for?
       - Production mechanism?   -> Which data set is the best to use?
       - Decay properties?             ->  Which kinematic region is the best to look for?
Difficulty in Reconstruction:
       - High track multiplicities -> Large combinatory   
          background! -> Do we have the sensitivity in searching for PQ?
General Search Strategy:
       ->  Start with claimed PQ’s
       ->  Choose all possible data sets for each search
       ->  Select known resonances with similar decay products and multiplicity
       ->  Use these known resonances as guidelines for PQ search
         - Advantages:
            - A quick starting point for selection cuts
            - Make sure we are able to reconstruct & see the known resonances
            - We could calculate the relative yields
         - Limitations:
            - We did not exhaust the search for  all the kinematic regions 
            - The cuts are not optimized for the PQ search

-        - Production cross section? -> Which PQ is the best to look for?
-        - Production mechanism?   -> Which data set is the best to use?
-        - Decay properties?             ->  Which kinematic region is the best to look for?
**Difficulty in Reconstruction:**
-        - High track multiplicities -> Large combinatory
-           background! -> Do we have the sensitivity in searching for PQ?
**General Search Strategy:**
**       **->**  **Start with claimed PQ’s
-        ->  Choose all possible data sets for each search
-        ->  Select known resonances with similar decay products and multiplicity
-        ->  Use these known resonances as guidelines for PQ search
-          - Advantages:
-             - A quick starting point for selection cuts
-             - Make sure we are able to reconstruct & see the known resonances
-             - We could calculate the relative yields
-          - Limitations:
-             - We did not exhaust the search for  all the kinematic regions
-             - The cuts are not optimized for the PQ search

**General Search Strategy **

- PENTAQUARK04,  Ming-Jer Wang

## c0search: Strategy & Samples

- PENTAQUARK04,  Ming-Jer Wang

## c0search: D & D* reconstructions

-               D0→ K−+		    D*+→ D0+

**K and ******** pass all tracking cuts**
**K and ******** form a good vertex with vertex ********2 < 30**
**     ****N(D**0) **~ ****3 M**** events **
**      ****σ****(D**0)** ~ 8 MeV/c2**

**Pion pass all tracking cuts**
**Pt(********) > 400 MeV**
**D0 and pion form a good vertex  **
**     ****with vertex ********2 < 30**
**1.845 <  M(D0) < 1.885 GeV/c2**
**     ****N(D*) ~****0.5 M**** events, **
** ****     ****σ****(D***) **~ 1.2 MeV /c2**

- PENTAQUARK04,  Ming-Jer Wang

## M

******c0****search: D1 & D2 reconstructions**

**M(D*****+****π**** ̅****)- ****M(D*+)      [GeV/c2]**

- PENTAQUARK04,  Ming-Jer Wang

## c0search: Proton Pt Distribution

- PENTAQUARK04,  Ming-Jer Wang

## c0search: Proton Identification

- PENTAQUARK04,  Ming-Jer Wang

## c0search: D*p Mass Spectrum

- PENTAQUARK04,  Ming-Jer Wang

## c0search: D*p Mass Spectrum

- PENTAQUARK04,  Ming-Jer Wang

## c0search: D*p Mass Spectrum

- PENTAQUARK04,  Ming-Jer Wang

## Reference signals D** are clearly reconstructed
    - with 14.7 K events
    - the combinatory BKG underneath is large
PID are used for the proton
With the selection cuts for D** & PID for proton, no evidence was  found for c0
Need more inputs from theorists on both the production mechanism & decay properties in order to design c0-specific cuts

-     - with 14.7 K events
-     - the combinatory BKG underneath is large
- PID are used for the proton
- With the selection cuts for D** & PID for proton, no evidence was  found for c0
- Need more inputs from theorists on both the production mechanism & decay properties in order to design c0-specific cuts

**Summary of ********c0****search**

- PENTAQUARK04,  Ming-Jer Wang

## + Search: Strategy & Samples

- PENTAQUARK04,  Ming-Jer Wang

## + Search: Proton ID with TOF

- PENTAQUARK04,  Ming-Jer Wang

## + Search: Known Resonances

- PENTAQUARK04,  Ming-Jer Wang

## + Search: Mass Resolutions

- PENTAQUARK04,  Ming-Jer Wang

## + Search: pK0S Mass Spectrum

- PENTAQUARK04,  Ming-Jer Wang

## Reference signals K*+, Λ(1520), Φ are clearly reconstructed
    -we have sensitivity to these known resonances 
    -the combinatory BKGs underneath are large
TOF is used for the proton ID
With the present selection cuts, no evidence was  found for + 
Need more inputs from theorists on both the production mechanism & decay properties in order to do further search

-     -we have sensitivity to these known resonances
-     -the combinatory BKGs underneath are large
- TOF is used for the proton ID
- With the present selection cuts, no evidence was  found for ******+**** **
- Need more inputs from theorists on both the production mechanism & decay properties in order to do further search

**Summary of  ********+**** search**

- PENTAQUARK04,  Ming-Jer Wang

##     Search : Strategy & Samples

- PENTAQUARK04,  Ming-Jer Wang

##     Search :  reconstruction

- PENTAQUARK04,  Ming-Jer Wang

##     Search :  Mass Spectra

- Displaced Track Trigger sample
- Inclusive Jet Trigger sample

- PENTAQUARK04,  Ming-Jer Wang

##     Search : Two-Track Trigger

- PENTAQUARK04,  Ming-Jer Wang

##     Search : Two-Track Trigger

- PENTAQUARK04,  Ming-Jer Wang

##     Search : Inclusive Jet Trigger

- PENTAQUARK04,  Ming-Jer Wang

##     Search : Inclusive Jet Trigger

- PENTAQUARK04,  Ming-Jer Wang

## Summary of     Search 

- •Reference signal (1530) is clearly reconstructed in
-   both data sets
- •With the present selection cuts, no evidence was  found for  ****
- •Need more inputs from theorists on both the
-   production mechanism & decay properties

- PENTAQUARK04,  Ming-Jer Wang

## PQ(uudcc ) -> J/Psi  proton
PQ(uudsc ) -> Ds-  proton
PQ(uuudc ) -> D0  proton
PQ(uuddc ) -> D-  proton

- PQ(**uudsc**** ) **-> Ds-  proton
- PQ(**uuudc**** ) **-> D0  proton
- PQ(**uuddc**** ) **-> D-  proton

**Ongoing Searches**

- PENTAQUARK04,  Ming-Jer Wang

## Summary & Outlook

- CDF Collaboration have searched for
**	********c****0,** ******+,**** ********     **states
- With no application of knowledge for pentaquark production mechanisms and decay properties in all analyses, no evidences of these states have been found
- We are vigorously searching for another 4 pentaquark states

- PENTAQUARK04,  Ming-Jer Wang