# Presentation: 108228

## Search for the H0 Dibaryon at KTeV

- Overview
- KTeV Detector
- Analysis
- Signal Mode
- Normalization Mode
- Transmission Effects
- Lifetime and Branching Ratio
- Results and Future Plans
- KTeV Collaboration:
- 	Arizona, UCLA,  UCSD, Chicago, Colorado, Elmhurst, Fermilab, Osaka, Rice, Rutgers, Virginia, Wisconsin
- Ram Ben-David
- Fermilab
- Rencontres de Moriond /QCD
- March 21-27, 1999

- Ram Ben-David

- Moriond QCD99

**Notes:**
KTeV - Kaons at the Tevatron.

Two experiments

E832 - search for direct CP violation in k->pipi
    measure direct cp  violation parameter Re(epsilon’/epsilon) via dependence of the final state on  cp  violation.

E799 - Approach SES for standard model predictions for rare decays involving direct CP violation:
      k-> pi0 l l

  1st measurement of pipiee
1st measurement of pipiee asymmetry.

## What is the H0  Dibaryon?

- It’s a 6*q *color singlet hadron:
*H**0** * = 		(*B *= 2, *S *= -2)
- Schematic deuteron wave function:
- Additional flavor *possibly* lowers the system’s energy through the color-hyperfine interaction:

- Ram Ben-David

- Moriond QCD99

## Theoretical Predictions for MH

- MH

- Ram Ben-David

- Moriond QCD99

## So What?

-  It would be a *new* form of matter, analogous to mesons and baryons.
- Increase knowledge of strong interactions.
- First of many (?) of multiquark states.
- Astrophysical implications.

- Ram Ben-David

- Moriond QCD99

## Recent Experimental Searches

- From D. Ashery,  Proceedings of* Hadron Spectroscopy*: *7th Int. Conf.* (1997)

- Ram Ben-David

- Moriond QCD99

## The H0 at KTeV

- Fully reconstruct the final state.
- First analysis to normalize to ’s  (S = -2)
- Test coalescense portion of the production model.
- Sensitive to the remaining mass window in Donoghue *et al*. model.     (PRD34, 3434, 1986)
- Test production at high energies: 		Rotondo’s model                   (PRD47, 3871, 1993)

- Signal
- Mode

- Normal
- Mode

- Ram Ben-David

- Moriond QCD99

## Highlights:
800 GeV/c  p on BeO target
clean and intense beams
long decay volume
hermetic detector
high resolution CsI EM calorimeter

new DAQ system w/online event filtering

- 800 GeV/c  *p* on BeO target
- clean and intense beams
- long decay volume
- hermetic detector
- high resolution CsI EM calorimeter
- new DAQ system w/online event filtering

- KTeV Spectrometer (Rare Decay Configuration)

- Ram Ben-David

- Moriond QCD99

## Final H0 Cuts

- Pt of *H**0*  vs. M*H*

- Ram Ben-David

- Moriond QCD99

## Mass and Momentum Distributions

- N

- 0  0D

- Ram Ben-David

- Moriond QCD99

## Result

- Ram Ben-David

- Moriond QCD99

## Test of Donoghue et al. Model

- Ram Ben-David

- Moriond QCD99

## Sensitivity to Lifetime 

- Assume  BR(*H*0N) = 100 %
- then BR(*H*0*p**p**p*

- Ram Ben-David

- Moriond QCD99

## Future Plans

- To probe for shorter lifetimes,  we need to close the distance between the target and the spectrometer
- 	 look for  *H*0’s produced in the 		regenerator.
- Based on  production rate in the regenerator,  estimate sensitivity of       100 *H*0’s per day.

- Ram Ben-David

- Moriond QCD99

## Conclusions

- Ruled out the remaining mass window for long lived *H*0’s as proposed by Donoghue *et al*.
- Sensitive to the range:
- nsec <*H *< 107 nsec
- First test of Rotondo’s production model (at high energies).
- Normalizing to ’s is a sensitive probe of coalescence.
- In KTeV99, we have the ability to search down to 0.5 **nsec).
- 	... in addition to the *H*0, there are some interesting Kaon results.

- Ram Ben-David

- Moriond QCD99