pp 510 GeV Pythia Dihadron Correlation with HardQCD on -- 2015.10.07

Updated on Sun, 2015-10-11 21:50. Originally created by yili on 2015-10-07 09:20.

Motivation:

Followed the pp 500 GeV near-side Dphi distribution shows a bump with |Deta|>1.3 in dihadron correlation

Here is pythia simulation with Hard QCD only.

I also checked SoftQCD (MB) one, but it needs too much statistics.

See master page: drupal.star.bnl.gov/STAR/blog/yili/master-page-dihadron-pp-500-gev

Dataset:

pythia8->SetFrame("CMS", 510.0);
pythia8->SetBlue("proton");
pythia8->SetYell("proton");

pythia8->Set("HardQCD:all = on");
pythia8->Set("PhaseSpace:mHatMin = 10");

Only pion, kaon, proton are used for refmult calcuation and dihadron correlations.

MPI ON and OFF will be compared.
Pythia default is MPI ON.

Code:
See attachment.

Result:

1. refmult distribution:
(events < 2 tracks are not included in histogram)

MPI ON	MPI OFF
	ppp

2. Delta eta - Delta phi distribution

MPI ON	MPI OFF

3. Delta eta distribution with |Delta phi| < 1

MPI ON	MPI OFF

4. Delta phi distribution with 1.3 < |Delta eta|<1.7

MPI ON	MPI OFF

5. Delta phi distribution with 1.3 < |Delta eta|<1.5

MPI ON	MPI OFF

Discussion:

I also tried to turn off ISR (initial state radiation) or FSR (final state radiation). The near-side jet tail still persists to |Delta eta| > 1.3

Groups:

The STAR experiment