Transcript Test of Tevatron Data with H1 Fitter

Mechanism of hadron
production in high energy
particle collisions
A. Bylinkin
(Supervisor: A. Rostovtsev)
XLI ITEP Winter School
12-19 February, 2013
Charge Particle Spectra and the Fit Function
Differential Invariant
Cross-Section
d 3
d 3
d 2
E 3 

d p ddypT dpT
dyd( pT 2 )
Boltzmann
exponent
pQCD
power-law
pT – transverse momentum, y - rapidity
The widely used approximation
d 2
A

2
dyd( pT ) (1  ETkin ) N
T *N
ETkin 
pT2  m2  m
e
New Approach
 ETkin / T

1
( ETkin ) n
A sum of exponential & power-law terms
Why the new approach matches
the data better?
Systematic defects in the data description using traditional approach
Experimental data divided over the values of the fit function in corresponding points
UA1 630GeV
RHIC 200GeV
²/ndf = 288/44 ²/ndf = 87/25
UA1 630GeV
RHIC 200GeV
²/ndf = 54/42 ²/ndf = 22/23
d 2
A

dyd( pT 2 ) (1  ETkin ) N
T *N
The new parameterization shows much better
approximation of the experimental data.
Qualitative model
2 Mechanisms of hadron production
1. Radiation of hadrons by valence quarks
Theses partons exist long before
the interaction and considered
as a thermalized statistical state
Boltzmann-like
exponential distribution
2. Virtual partons exchanged between
colliding partonic systems
BFKL Pomeron exchange in QCD
power-law spectrum (typical for pQCD)
R=
Power-law _
Exp + Power-law
The model was discussed with Mihail Ryskin.
Type of produced particle
QCD-fluctuations are democratic to quark flavour
Prediction:
Kaon spectra should have
less exponential distribution then pion
exponent
power-law
R=
Power-law _
Exp + Power-law
power-law
No exponent
Dependence of the spectra shape
on multiplicity
Charge multiplicity is proportional to the number of
Pomerons involved
Prediction:
Exponential contribution will
decrease with the increase of multiplicity
STAR data
R=
Power-law _
Exp + Power-law
Energy of Collision
The number of pomerons involved is increasing with the
growth of the collision energy
Prediction:
Exponential contribution will
decrease with the increase of √s
ISR, UA1, CDF, LHC data
R=
Power-law _
Exp + Power-law
Dependence of the spectra
shape on pseudorapidity
In proton fragmentation region the role
of valence quarks is more important
Charge particle pseudorapidity Prediction: Dominance of exponential
distribution at √s ~ 630 Gev
term in the high rapidity region
UA1 data
Pomeron
exchange
Proton
fragmentation
R=
Power-law _
Exp + Power-law
Dependence of the spectra shape
on the type of colliding particles
Exponential term is due to valence quarks
γp-collisions
transitionshould have
Prediction: In
Spectra
in γγ-collisions
two regimes of hadroproduction
power-lawbetween
term only
can be observed
ep-collisions at HERA measured by the H1 experiment
are the unique possibility to test this prediction
Qualitative prediction of the model
R=
Power-lawUA1
_ data
Exp + Power-law
Measured data will be published
L3 data
Tracks measurable in H1
experiment at HERA
soon! (DESY, Hamburg)
Conclusion
• Standard approximation was shown to provide
poor description of the experimental data.
• New better parameterization function was
found.
• Qualitative model of charge particle production
was introduced.
• Predictions of the model were tested.
• An analysis of charge particle spectra in H1
experiment is proposed.
Thank you for your attention!
References
[1] Systematic studies of hadron production spectra in collider experiments
A.Bylinkin and A.Rostovtsev, arXiv:1008.0332 [hep-ph].
[2] Anomalous behavior of pion production in high energy particle collisions
A.Bylinkin and A.Rostovtsev,Eur.Phys.J.C72(2012)1961,arXiv:1112.5734
[3] Comparative Analysis of Pion, Kaon and Proton Spectra Produced at
PHENIX
A.Bylinkin and A.Rostovtsev, arXiv:1203.2840 [hep-ph].
[4] An analysis of charged particles spectra in events with different charged
multiplicity.
A.Bylinkin and A.Rostovtsev, arXiv:1205.4432 [hep-ph].
[5] A variation of the charged particle spectrum shape as function of rapidity in
high energy pp collisions.
A.Bylinkin and A.Rostovtsev, arXiv:1205.6382. [hep-ph]
[6] Parametrization of the shape of hadron-production spectra in high-energy
particle interactions
A.A. Bylinkin, A.A. Rostovtsev, Phys.Atom.Nucl. 75 (2012) 999-1005,
Yad.Fiz.75 (2012) 1060-1066
[7] A photon-proton mariage
A.A. Bylinkin, A.A. Rostovtsev. e-Print: arXiv:1209.0958 [hep-ph]
Back up slides
R Value
The relative contribution of exponential and power-law
terms can be calculated by integrating each term by
transverse momentum from 0 to the upper bound of
the kinematical region
Correlation Between Parameters
T and Te parameters in the power-law
and exponential terms of the fit function
are strongly correlated with each other
Better approximation is not just a result of exceeding
the number of parameters of the fit function
J/ψ Spectra
J/ψ has no exponential term in its spectrum
Comparison with MC Data
Hypothesis: production of pions via multiple cascade decays results in
the transformation of their spectra into an exponential distribution.
Statement: decay processes are described quite accurately in Pythia
MC generated spectrum for minimum bias
events in pp-collisions at √s = 630GeV
MC and experimental data divided over the fit
function obtained for the experimental spectrum
MC generators don’t reproduce the spectra shape of the experimental data
Dependence of the spectra
shape on the type of produced
particle
QCD-fluctuations are democratic to quark flavour
Prediction:
Kaon spectra should have
less exponential distribution then pion
Phenix data
π±
R = 0.25
K±
R = 0.72
p,pbar
R = 0.82