Momentum Correlations Status of PPR 6.3, Momentum Correlations Soft Physics Meeting, 03.05.2005, Jan Pluta, Warsaw University of Technology

The structure - shifted by Mercedes C

The structure (2)

Mercedes changes in the text Consistent notation New version of “Conclusion from experiments at AGS, SPS and RHIC” Some changes in the structure, Language corrections New figures Jan’s comment: Keep “small relative velocities”.

added by Mercedes

...added by Mercedes ...but pleasse, suply the “oscillations in transverse radii” (M.Lisa et al.)

New Elements Nonidentical Particle Correlations

Nonidentical particle correlations (The idea: assymmetry analysis) Catching up Effective interaction time larger Stronger correlation Moving away Effective interaction time smaller Weaker correlation “Double” ratio Sensitive to the space-time asymmetry in the emission process Kinematics selection R.Lednicky, V. L.Lyuboshitz, B.Erazmus, D.Nouais, Phys.Lett. B373 (1996) 30.

STAR: Correlation functions and ratios Good agreement for like- sign and unlike-sign pairs points to similar emission process for K+ and K- CF Out Clear sign of emission asymmetry Side Two other ratios done as a double check – expected to be flat Long Preliminary by Adam Kisiel

STAR: Hit merging in the TPC Tracks can cross in the TPC for pairs with only one sign of k*Side If the tracks cross – they can merge, if they merge at the outer part of the TPC, they are not tracked Cut rejects from the denominator pairs, that would be merged if in the same event

ALICE: Nonidentical particles (pi+,K-) Assumed time shift by Emilia Lubańska

ALICE: Correlation functions (pi+,K-) by Emilia Lubańska

Double ratios: out,side,long (physics + merging) by Emilia Lubańska

HBT correlations in ITS stand alone

Stand alone ITS for HBT analysis (Alberto Pulvirenti) Motivation: some running time for a “high rate” data taking, e.g. for muon studies, in this case the TPC (slow response) cannot be used, is ITS capable to perform track reconstruction and perform HBT studies? Tracking in the ITS stand alone: the first attempt made in (1999) Alice-ITS-99-34, SUBATECH-99-09 new version based on the Denby-Peterson Neural Tracking, full C++ implementation into AliRoot, SIMULATIONS 160 events, HIJING param. 4000 particles/event “good” track - 5 points sharing the same GEANT label, efficiency - (70-80)%

Stand alone ITS for HBT analysis (Alberto Pulvirenti) ANALYSIS: only one dim. analysis with respect to Qinv The method of “weights” by R.Lednicky used to create correlations Perfect PID assumed ( realistic PID “under study”) HBT analyser of P. Skowronski used to calculate correlation function

Stand alone ITS for HBT analysis (Alberto Pulvirenti) RESULTS Gaussian source distribution with (6, 8, 10, 12)fm assumed Intercept parameter: lambda (0.5,0.75, 1.0) open points - no correlations full points - R=8fm corrected correlation function

Stand alone ITS for HBT analysis (Alberto Pulvirenti) CONCLUSIONS Correlation effect is clearly visible. Linear correlations of the results with the simulated values. Reconstructed values underestimate the simulated ones. Works are in progress.

Direct photons interferometry

Direct photons interferometry with PHOS (by Dmitri Peressounko ) Specific features of direct photons: emitted in all stages of the collision, keep information about the “beginning/hottest” stage of the collision, Kt dependence select contribution from different stages, do not suffer from FSI, direct interpretation of the correlation funct. but most of photons are produced in decay of long living hadrons, this contribution can be estimated and subtracted. Registration of two photons by PHOS: R=5fm => Q=50MeV If Kt=1GeV, Q/Kt=0.05; 460cm*0.05=23cm - distance between photons in PHOS One crystal unit =2.5cm Two local maxima should be separated by one crystal unit Size of the cluster increase logarithmically with energy

Direct photons interferometry with PHOS (by Dmitri Peressounko ) Unfolding algorithm Resolution of: relative distance - 0.4cm energy: sig(E)/E - 4% systematic - increasing (small influence on correl.) Probability to unfolded (filed boxes) and find cluster separated (empty boxes) as a function of distance between them

Direct photons interferometry with PHOS (by Dmitri Peressounko ) Resolution: Qside Qout

Direct photons interferometry with PHOS (by Dmitri Peressounko ) Splitting of complicated clusters: p, p(bar), n, n(bar) Contribution much smaller than those of direct photons

Direct photons interferometry with PHOS (by Dmitri Peressounko ) Photon pairs in high multiplicity envirnment HILING, central Pb+Pb collisions photon conversion before PHOS, heavier resonances

Direct photons interferometry with PHOS (by Dmitri Peressounko ) CONCLUSION Possibility of measurement of two-photon correlations up to Kt=3MeV, even in central Pb+Pb collisions accessing space-time informatin about all major stages of the collisions.

Influence of Resonances

Resonance influence on particle correlations (Ludmila Malinina and Boris Batiounia) Motivation: 2/3 of pions comes from resonance decays, It makes the interpretation of correlation results more complicated Simulation: Thermal source with Boltzmann gas of resonances: short lived: e.g. Rho - mean lifetime - 1.3 fm/c moderatelylived: omega - mean lifetime - 23.4 fm/c, long lived: etha’ - mean lifetime - 1000 fm/c secondary interactions: sigma=400mb

Resonance influence on particle correlations (Ludmila Malinina and Boris Batiounia) Correlation function for different resonance sources

Resonance influence on particle correlations (Ludmila Malinina and Boris Batiounia) 3-dim. correlation function for omega source and rescattering

Simulation chain

Correlations in (pp) collisions

Correlations in (pp) collisions (Piotr Skowroński) 1. The size expected ...1-2 fm (1fm assumed in simulations) 2. 105 events generated using PYTHIA (correlatins outside the interferometry region for very small multiplicities, Nch>5 taken) 3. Analysis the same as for Pb+Pb

Correlations in (pp) collisions (Piotr Skowroński)

Two Particle Resolution (Piotr Skowroński, Grzegorz Gałązka) Resolution values are very close to the ones in Technical Proposal Improvement in Qout is connected to better pt resolution and higher magnetic field 1 1.3 0.5 0.6 11 6.3 600 < pt 0.8 1.1 0.4 6.4 4.2 300< pt < 600 0.9 3.4 2.7 pt < 300 TP PDC04 Qlong Qside Qout Resolution (r.m.s) [MeV] pt range [MeV]

Two Particle Resolutions (2)   Resolution (r.m.s) [MeV] Qinv Qout Qside Qlong PDC04 TP p+p+ 0.9 1.3 3.4 3.8 0.4 1 0.8 K+K+ 2.3 4.2 6.4 9.5 0.6 0.5 1.9 pp 4.0 8.0 9.4 13.0 0.7 3.2 4.3 p+K-  x x 4.4 4.1 1.2 1.7 1.1 p+p 5.8 2.1 1.8 K+p 8.3 1.0 2.6

New data on reslution

New data on reslution

New data on reslution

New data on reslution

Track Merging – ident. (1) Anti-Merging cut as implemented by STAR Cutting on average distance between two tracks in TPC Space coordinates of tracks are calculated assuming helix shape using track parameters as reconstructed in the inner part of TPC

P I D

Single event pion-pion interferometry... by Hania GOS

CorrFit CorrFit is a tool developed in STAR by Adam Kisiel CorrFit is able to find parameters that fits correlation function taking to the account: Final State Interaction (Coulomb and strong) They are not corrected for but treated as a source of correlations! Detector resolution Can work with any model of the freeze-out distribution Not limited to Gaussian source distribution ! Is able to fit non-identical particles correlation functions

2 notes in preparation

...to do Finish the text of PPR (2-4 weeks) Continue works with resoltion, PID, mergind etc. Finish works with CORFIT Cooperate with other groups of Soft Physics at ALICE (asHBT, strange particles etc.) Cooperate with theorists; EPOS+Hydro, etc. Be ready for data taking!!! (2007)