1. Bose-Einstein correlations in 8 TeV DATA with jets
Comenius University, Bratislava
Sofiia Hyrych,
S.Tokár, I. Sýkora, R. Astaloš, T. Ženiš

2. Motivation
We want to study a possible influence of jets on Bose-Einstein correlations studies.
For this purpose we use 8 TeV tt-bar data which include ≥ 4 jets and compare it to 7 TeV Minimum Bias data.

3. Selection criteria Lint ≈ 20.3 fb−1
ATLAS √s = 8 TeV data
Lint ≈ 20.3 fb−1
tt-bar semileptonic decay channel (lepton + jets)
(Standard ttbar) Selection criteria:
- Exactly 1 lepton with pT > 25 GeV and 0 ≤ |η| ≤ 2.5
- At least 4 jets with pT > 25 GeV and 0 ≤ |η| ≤ 2.5
- At least 1 b-tagged jet, using MV1 at ≈ 70 % efficiency
Lepton = electron, muon

4. MC and Data comparison for muons
Q - distribution for track pairs from the same jet
For all pairs
Track pT >0.4 GeV
Track pT >0.6 GeV

5. MC and Data comparison for muons
Q - distribution for track pairs from the same jet
For all pairs
Track pT >0.8 GeV
Track pT >1.0 GeV

6. MC and Data comparison for muons
Q - distribution for track pairs from the same jet
For all pairs
Track pT >1.2 GeV
Track pT >1.4 GeV

7. MC and Data comparison for electrons
Q - distribution for track pairs from the same jet
For all pairs
track pT >1.0 GeV
track pT >1.4 GeV

8. Q-distributions for various pT cuts (muons)
Tracks in the pair from the same jet
All pairs

9. Q-distributions for various pT cuts (electrons)
Tracks pairs from the same jet
All track pairs

10. Normalized Q-distributions for various pT cuts (for muons) compared to 7 TeV MinBias

11. Ratio of the C2 functions for tt-bar and MinBias data

12. Unlike-sign Q-distributions for MinBias and tt-bar DATA (muons)
Track pairs from the same jet
All track pairs
Track pT >400MeV
Track pT >1400MeV

13. Unlike-sign Q-distributions for MinBias and tt-bar DATA (electrons)
Track pairs from the same jet
All track pairs
Track pT >400 MeV
Track pT >1400 MeV 13

14. Conclusions We have seen a BEC-like effect in the tt-bar events.
The BEC peak in tt-bar events is very similar to the one in the MinBias events.
Jet track pairs have a tendency to fill low Q region, but it looks that they influence BEC peak weakly.
Hard to distinguish between the jet effect, though small and the BEC one in tt-bar events.
It is difficult to compare the tt-bar and MinBias data, because of different dynamics of the events resulting into different pT and Q distributions.
We can continue to compare the fit results of the two event samples if needed -- ?