Trigger identified V 0 correlations in AuAu collisions

Trigger - identified V 0 correlations in Au+Au collisions at STAR Léon Gaillard University of Birmingham HOT QUARKS 2006 Sardinia, Italy

Outline • Jet Tomography • Same side features in Au+Au • V 0 - triggered correlations • Analysis • Results • Outlook Léon Gaillard, University of Birmingham 12/11/2021 1

Jet Tomography Azimuthal correlations tell half the story… ~ d+Au same side away side Léon Gaillard, University of Birmingham 12/11/2021 2

Same side features in Au+Au d+Au Au+Au 0 -5% Same side peak broader in and peak sits atop a ridge 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c In vacuo (pp) fragmentation static medium flowing medium broadening anisotropic shape Eur. Phys. J. C 38 461 Léon Gaillard, University of Birmingham 12/11/2021 3 see talk by Joern Putschke

Meson-Baryon difference Associated track selection Trigger track selection Léon Gaillard, University of Birmingham 12/11/2021 4 J. Phys. G (2004) 30 S 963 RCP J. Phys. G (2005) 31 S 399 • Ridge is seen when p. T, assoc. < 3 Ge. V/c • Spectra - Thermal dominated • Correlations - more sensitive to shower - thermal contributions • Should the baryon-meson difference feature in correlations?

Identified correlations p Reconstructed V 0 3. 0 < p. T < 6. 0 Ge. V/c p K 0 short What causes the ridge? Invariant mass (Ge. V/c 2) Compare correlations involving baryons with anti-baryons and mesons neutral strange particles ( K 0 short) are a good source of all three out to high-p. T Léon Gaillard, University of Birmingham 12/11/2021 5

Ridge Analysis I Unidentified charged tracks in Au+Au 3. 0 < p. T, trigger < 4. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c (jet + ridge + v 2) - (ridge + v 2) = jet yield Léon Gaillard, University of Birmingham 12/11/2021 6

Bin counting results K 0 s-Ch 0 -5% 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c preliminary trigger V 0 } K 0 short 5 -10% 10 -40% 40 -60% n. Part Jet yield = yield( ) - yield( ) 60 -80% • Jet yield constant with centrality… • Little dependence seen on window • separation between baryon and meson triggered yields? Léon Gaillard, University of Birmingham 12/11/2021 7

Bin counting results K 0 s-Ch 0 -5% 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c preliminary trigger V 0 } K 0 short 5 -10% 10 -40% 40 -60% n. Part Jet yield = yield( ) - yield( ) 60 -80% • Baryon and meson triggered yields are consistent in online central triggered events (x 5 stats) • Some systematic effects still under investigation Léon Gaillard, University of Birmingham 12/11/2021 8

Ridge Analysis II Unidentified charged tracks in Au+Au 3. 0 < p. T, trigger < 4. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c 1/(Ntrig ) d. N/d( ) Analysis projection : Jet + Ridge + v 2 1/(Ntrig ) d. N/d( ) Léon Gaillard, University of Birmingham 12/11/2021 9

Projection studies - K 0 Ch sibling mixed event corrected preliminary 0 -5% (online) sibling mixed event corrected preliminary 5 -40% sibling mixed event corrected preliminary 40 -80% Léon Gaillard, University of Birmingham 12/11/2021 10

Projection studies - K 0 Ch preliminary Fit is poorly constrained 0 -5% Peak is too shallow/wide (online) preliminary 5 -40% preliminary 40 -80% preliminary Léon Gaillard, University of Birmingham 12/11/2021 11

Projection studies - (La+Lb)Ch sibling mixed event corrected preliminary 0 -5% (online) sibling mixed event corrected preliminary 5 -40% sibling mixed event corrected preliminary 40 -80% Léon Gaillard, University of Birmingham 12/11/2021 12

Projection studies - (La+Lb)Ch preliminary Fit is poorly constrained 0 -5% Peak is too shallow/wide (online) preliminary 5 -40% preliminary 40 -80% Léon Gaillard, University of Birmingham 12/11/2021 13

Projection studies - d. Phi yields 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c trigger V 0 jet + ridge yield ( fit) K 0 short • d. Phi jet plus ridge yield increasing with centrality • d. Eta jet yield poorly defined Léon Gaillard, University of Birmingham 12/11/2021 14

summary • • Two particle correlations with V 0 triggers Jet yield appears flat with centrality Jet + ridge projection increases with centrality Baryon and Meson triggers consistent within statistics Baryon triggers Meson triggers preliminary 5 -40% Future work • Investigate systematic differences between V 0 triggers • Extend range to • Identified associated V 0 s For more V 0 correlations see Jana Bielcikova’s talk Léon Gaillard, University of Birmingham 12/11/2021 15

Backup Léon Gaillard, University of Birmingham 12/11/2021 16

Constituent Quark Scaling anisotropic flow Low p. T: < 2 Gev/c • strong anisotropic flow exhibited • described by hydrodynamic models with infinitesimal mean free path Intermediate p. T: 2 Ge. V/c < p. T < 6 Ge. V/c • constituent quark scaling • quark coalescence Meson Baryon Hard Thermal Quark recombination Léon Gaillard, University of Birmingham 12/11/2021 17 2 4 6 8

V 2 correction We see a cos(2 modulation of background in Au. Au due to anisotropy of collision system reaction plane particles emerge preferentially in the reaction plane Léon Gaillard, University of Birmingham 12/11/2021 18

efficiency correction Mean p. T of associated tracks Scale up histograms by reconstruction efficiency of associated tracks Léon Gaillard, University of Birmingham 12/11/2021 19

Acceptance correction Anti-merging cut I preliminary real correlation Limited acceptance of STAR TPC introduces pair-wise shape. Correction using event mixing making pairs with tracks from different events Mixed event overcorrects at the origin because pairs are included with separations smaller than the detector resolution. These are removed by comparing separations of the hits that form the tracks mixed event Corrected correlation Léon Gaillard, University of Birmingham 12/11/2021 20

helix intersections with pad rows after local co-ordinate transformation Antimerging cut II no fmh cut fmh<=0. 2 fmh<=0. 1 Fmh==0. 0 fmh >= 0. 1 found to be optimal Léon Gaillard, University of Birmingham 12/11/2021 21

d. Eta-d. Phi Ch. Ch d+Au event 1 { event 2 event 3 Away side is spread out in pseudorapidity difference because the system is not viewed from the centre of momentum frame of the parton scatter Léon Gaillard, University of Birmingham 12/11/2021 22 + +

Jets in heavy Ion Collisions hadrons prediction: huge radiative energy loss �� prediction: screening delays fragmentation quark di-quark Gluon bremsstrahlung gold nucleus Jet cone Parton energy loss depends on path length, L, and not parton energy 2 L E med ~ sq� � where q is transport coefficient Léon Gaillard, University of Birmingham 12/11/2021 23 gluon density

Interpretation In vacuo (pp) fragmentation static medium flowing medium broadening anisotropic shape Eur. Phys. J. C 38 461 What causes the ridge and jet broadening? • Radiated gluon contributes to ridge and broadening Armestro Eur. Phys. J. C 38 461 • Coalescence of quarks from the medium Chiu & Hwa Phys. Rev. C 72: 034903, 2005 • Collective flow combined with jet-queching Voloshin nucl-th/0312065 Léon Gaillard, University of Birmingham 12/11/2021 24

Ridge Properties absolute ridge yield = {(jet+ridge) - (jet)} ridge yield relative ridge yield = {(jet+ridge) - (jet)} / (jet) preliminary central peripheral preliminary pt, assoc. > 2 Ge. V transverse momentum of trigger Relative ridge yield decreasing with trigger p. T Absolute ridge yield constant as function of trigger p. T Léon Gaillard, University of Birmingham 12/11/2021 25

Relativistic Heavy Ion Collider Magnet STAR PHENIX PHOBOS RHIC BRAHMS STAR Time Projection Chamber RHIC AGS Two 2. 4 mile circumference rings Six intersection points Au 4 m + Au up to c. m. s 200 Ge. V/n Asymmetric beams Polarised proton source TANDEMS Long Island, NY Léon Gaillard, University of Birmingham 12/11/2021 26

Bin counting results K 0 s-Ch 0 -5% 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c preliminary trigger V 0 } K 0 short 5 -10% 10 -40% 40 -60% n. Part Jet yield = yield( ) - yield( ) 60 -80% • Vary size of windows Léon Gaillard, University of Birmingham 12/11/2021 27

Bin counting results 0 -5% 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c preliminary trigger V 0 } K 0 short 5 -10% 10 -40% 40 -60% n. Part Jet yield = yield( ) - yield( ) 60 -80% Léon Gaillard, University of Birmingham 12/11/2021 28

Bin counting results K 0 s-Ch 0 -5% 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c preliminary trigger V 0 } K 0 short 5 -10% 10 -40% 40 -60% n. Part Jet yield = yield( ) - yield( ) 60 -80% • Baryon and meson triggered yields are consistent in online central triggered events (x 5 stats) Léon Gaillard, University of Birmingham 12/11/2021 29

Bin counting results 0 -5% 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c preliminary trigger V 0 } K 0 short 5 -10% 10 -40% 40 -60% n. Part Jet yield = yield( ) - yield( ) 60 -80% • Slight increase in most central yields • Broad jet peak Léon Gaillard, University of Birmingham 12/11/2021 30

Projection studies - d. Phi yields 3. 0 < p. T, trigger < 6. 0 Ge. V/c 2. 0 < p. T, assoc < 3. 0 Ge. V/c trigger V 0 jet + ridge yield ( fit) jet yield (bin counting) K 0 short • d. Phi jet plus ridge yield increasing with centrality • d. Eta jet yield poorly defined • Compare to jet yield from bin counting Léon Gaillard, University of Birmingham 12/11/2021 31