1. 9-SEPT-2003 1 Charge Fluctuations in π+p and  +p Collisions at 250GeV/c Yuanfang Wu 1. Introduction 2. Results The dependency of charge fluc. on Y The dependency of charge fluc. on n 3. Summary

2. 9-SEPT-2003 2 1.Introduction ► Charge fluc. → a new signal of QGP PT ► Measures charge ratio fluc.: net charge fluc.:

3. 9-SEPT-2003 3 1.Introduction ► Theoretical predictions for D-measures Random: D(Q) ~ 4 HG: D(R) ~ 3 - 4 HG: D(R) ~ 3 - 4 QGP : D(R) ~ 0.75 - 1 QGP : D(R) ~ 0.75 - 1 ► Corrections ► Motivations Which measure is better and if the corr. are proper? Data on h-h collisions is absent. Data on h-h collisions is absent.

4. 9-SEPT-2003 4 1.Introduction Data ► Data : π+ p and  + p Collisions at 250GeV/c ( NA22 Coll. ) ( NA22 Coll. ) 0.001GeV/c < p t < 10 GeV/c full 4π acceptance A total of 44 524 NSD events 0.001GeV/c < p t < 10 GeV/c full 4π acceptance

5. 9-SEPT-2003 5 2. Results The dependency of the fluc. on Y 1) & 2) & 3) &

6. 9-SEPT-2003 6 2. Results n ch dis. for diff. |y| < y cut 1) |y|<2, even & odd are the same. 2) |y|<2.5, even & odd start to separate. It first happens at large n ch. 3) full range, only even left.

7. 9-SEPT-2003 7 2. Results n ch The dependency of the fluc. on n ch at |y| < 2.5

8. 9-SEPT-2003 8 2. Results The dependency of the fluc. on n ch at |y|<3

9. 9-SEPT-2003 9 3. Summary ☺ and both have strong Δy dependence. ☺ in diff. Δy are much smaller than those of random and HG, but pass through the band of random and HG, but pass through the band of QGP. QGP. stays between the bands of HG and QGP and stays between the bands of HG and QGP and show no Δy dependence at large Δy. show no Δy dependence at large Δy. ☺ The and develop a peak with increasing of Δy, lying partly in the bands for a HG and a QGP, of Δy, lying partly in the bands for a HG and a QGP, respectively, but their corrected versions always above respectively, but their corrected versions always above the band for the HG and keep increasing with the size the band for the HG and keep increasing with the size of Δy. of Δy.

10. 9-SEPT-2003 10 3. Summary ☺ and both have n ch dependence. ☺ has better record in net charge fluc. between even and odd n ch than the charge ratio ones. ☺ smear the existent differences between even and odd charged n ch, while the make their n ch dependence disappear within experimental errors. ☺ PYTHIA can reproduce the net charge and charge ratio fluc. in different Y cut and for different n ch. However, PYTHIA over-estimates the fluc. of odd n ch at |y|<3.