Highlights from Highlights from the STAR experiment the STAR - - PowerPoint PPT Presentation
Highlights from Highlights from the STAR experiment the STAR experiment Hanna Zbroszczyk for the STAR Collaboration for the STAR Collaboration Faculty of Physics, Warsaw University of Technology supported by National Science Centre, Poland
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Hanna Zbroszczyk
for the STAR Collaboration for the STAR Collaboration
Faculty of Physics, Warsaw University of Technology
supported by National Science Centre, Poland MESON 2018, Kraków, 9th June 2018
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RHIC
BRAHMS PHOBOS PHENIX STAR
AGS
TANDEMS
R Relativistic elativistic H Heavy eavy I Ion
Collider (RHIC)
Brookhaven National Laboratory (BNL), Brookhaven National Laboratory (BNL), New York New York
2 concentric rings of 1740 superconducting magnets
3.8 km circumference
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The The S Solenoidal
Tracker racker A At t R RHIC HIC
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Introduction Introduction
RHIC Top Energy p+p, p+Al, p+Au, d+Au,
3He+Au, Cu+Cu, Cu+Au,
Ru+Ru, Zr+Zr, Au+Au, U+U QCD at high energy density/temperature Properties of QGP, EoS Beam Energy Scan Au+Au 7.7-62 GeV QCD phase transition Search for critical point Turn-off of QGP signatures Fixed-Target Program Au+Au =3.0-7.7 GeV High baryon density regime with 420-720 MeV
Introduction Introduction
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Introduction Introduction
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Introduction Introduction
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1) D 1) D0
0 – Open heavy flavor
– Open heavy flavor
electromagnetic field (eB ~ 10 18 G at RHIC)
positive and negative charm quarks (CQs) can get deflected by the initial EM force
quarks induced by this initial EM field
fields
much larger than the light quarks
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symmetric in rapidity at non-zero rapidity, charm quarks production points are shifted from the bulk
flavors
heavy flavor v1 (v1 -slope) Charm-Quark >> (v1 -slope) Light-Quark
(D0) v1 can be used to constrain drag coefficients in conjunction with v2 and RAA
1) D 1) D0
0 – Open heavy flavor
– Open heavy flavor
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1) D 1) D0
0 – Open heavy flavor
– Open heavy flavor
Recent hydro model with initial EM field predicts v1 -split between the D and anti- D meson D meson v1 greater than the anti-D Predicted difference in v1 is about 10 times smaller than the average v1
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Significant suppression at low pT with no strong centrality dependence, Suppression at high pT decreases towards more peripheral collisions. Non-prompt D0 RAA study has been performed, need better precision measurements to understand mass dependence of energy loss.
1) D 1) D0
0 – Open heavy flavor
– Open heavy flavor
STAR data was re-analysed due to error found durring analysis → erratum will be published soon
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1) D 1) D0
0 – Open heavy flavor
– Open heavy flavor
First First evidence of non-zero directed flow for heavy flavor Both D Both D0 and D0 show negative v1 -slope near mid-rapidity Heavy flavor v1 > light flavor v1 Data can be used to probe initial matter distribution Current precision is not sufficient to draw conclusion on magnetic field induced charge separation of heavy quarks Non-prompt D0 RAA study has been performed, need better precision measurements to understand mass dependence of energy loss.
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2) Initial state physics 2) Initial state physics
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2) Initial state physics 2) Initial state physics
Q-cumulant method (traditional) Two-subevent method Sensitive to flow fluctuations
15 Φ - azimuthal angle
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2) Initial state physics 2) Initial state physics
Strong dependence of v2{2} and v2{4} on collision centrality more significant for higher collision energies Weak dependence of v2{2}/v2{4} on collision centrality
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2) Initial state physics 2) Initial state physics
Weak dependence of v2{2}, v2{4} and v2{2}/v2{4}
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2) Initial state physics 2) Initial state physics
Significant dependence of v2{2}, v2{4} and v2{2}/v2{4} on collision centrality for different A+A collisions
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2) Initial state physics 2) Initial state physics
Anisotropic flow magnitude is sensitive to:
Weak dependence of v2{2}, v2{4} and v2{2}/ε2{2}
Are dynamical final-state fluctuations significantly less than the initial-state fluctuations?
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2) Initial state physics 2) Initial state physics
Strong dependence of v2{2}, v2{4} on collision centrality, collision energy, transverse momentum Weak dependence of v2{4}/v2{2} and v2{2}/ε2{2} (elliptic flow fluctuations) on the size of colliding system and: collision centrality, collision energy, transverse momentum Flow flucuations are dominated by the fluctuations of the initial state eccentricity Similar viscous coefficient for different colliding systems
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3) Fixed target mode 3) Fixed target mode
Collider mode is unusable for ⎷sNN<7.7 GeV Fix target mode is able to cover ⎷sNN from 3.0 GeV to 7.7 GeV BES goals:
transition
Critical Point
signatures
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3) Fixed target mode 3) Fixed target mode
(1)
Spectra corrections: Detector efficiency Detector acceptance (each rapidity window) Energy loss
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3) Fixed target mode 3) Fixed target mode
Negavtive pions spectra are consistent with AGS results.
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3) Fixed target mode 3) Fixed target mode
Directed flow for pions and protons with fit describing mid- rapidity region. Directed flow of protons agrees with AGS results.
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3) Fixed target mode 3) Fixed target mode
Directed flow for Λ and K0
S particles and their fits describing mid-rapidity
region.
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3) Fixed target mode 3) Fixed target mode
HBT radii for pions are consistent with AGS results.
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3) Fixed target mode 3) Fixed target mode
High-baryon density regime will be accessible with the Fix Target mode in STAR!
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4) Femtoscopy 4) Femtoscopy
Single- and two- particle distributions Single- and two- particle distributions
P
1( p
)=Ed N d
3 p
=∫ d
4 x
S (x , p )
S(x,p) – emission function: the distribution
with x and p
C ( p
1 ,
p
2)=
P
2( p 1, p 2)
P
1( p 1)P 1(p 2)
The correlation function The correlation function
P
2( p 1 ,
p
2)=E 1 E 2
d N d
3 p 1d 3 p 2
=∫ d
4 x 1 S
(x
1 ,
p
1)d 4 x 2S
(x
2 ,
p
2)Φ(x 2, p 2∣x 1, p 1)
Pair Rest Frame reference
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4) Femtoscopy 4) Femtoscopy
0.05 0.1 k* [GeV/c]
Identical baryon- baryon Identical baryon- baryon
Quantum Statistics- QS QS
Final State Interactions- FSI FSI
Coulomb
Strong Non-identical baryon- Non-identical baryon- (anti)baryon (anti)baryon
Final State Interactions- FSI FSI
Coulomb
Strong
UrQMD Au+Au UrQMD Au+Au
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4) Femtoscopy 4) Femtoscopy
No significant difference between proton-proton and antiproton-antiproton correlation functions
proton-proton @39 GeV antiproton-antiproton @39 GeV
STAR Preliminary STAR Preliminary QM 2018 QM 2018
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4) Femtoscopy 4) Femtoscopy
Radii from proton-proton and antiproton-antiproton systems differ from those from proton- antiprootn system → → Residual Correlations. Residual feed-down correction needs to be applied.
proton-proton @39 GeV proton-antiproton @39 GeV
STAR Preliminary STAR Preliminary QM 2018 QM 2018
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4) Femtoscopy 4) Femtoscopy
Energy dependence more significant for proton-proton than for proton-antiproton system.
proton-antiproton, centrality 0-10% proton-proton, centrality 0-10%
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QM 2018 QM 2018
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0-10% 10-30% 30-70%
STAR Preliminary
Feed-down correction may decrease significance of centrality dependence.
4) Femtoscopy 4) Femtoscopy
QM 2018
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antiproton-antiproton correlation functions at √sNN = 39 GeV
correction required
4) Femtoscopy 4) Femtoscopy
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5) Hypertriton 5) Hypertriton
Hyperon-Nucleon:
QCD theory
anti-hypertriton provide insight into H-N interactions and the CPT symmetry
and nucleon phase-space of the system freeze-
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5) Hypertriton 5) Hypertriton
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5) Hypertriton 5) Hypertriton
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5) Hypertriton 5) Hypertriton
Worldwide binding energy
3 ΛH of experimental
measurements. Measurements of the mass-
between light nuclei and anti- nuclei.
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Summary Summary
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Upgrades Upgrades
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Upgrades Upgrades
Grazyna Odyniec/LBNL
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Grazyna Odyniec/LBNL
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2) Initial state physics 2) Initial state physics
Strong dependence on collision energy Weak dependence on collision centrality
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3) Small systems 3) Small systems
Near-side ridge observed in High Multiplicity (HM) of d+Au collisions
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3) Small systems 3) Small systems
Low multiplicity subtraction scaled by short-range near-side (|Δη|<0.5) jet yield Short-range near-side jet modification = long-range away-side jet modification Template fit A new method by ATLAS Collaboration away-side jet shape can be measured in Low Multiplicity (LM) events scaled by ”F” parameter (due to jet modification)
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3) Small systems 3) Small systems
v2 without subtraction is larger larger than that with subtraction for both methods. The subtraction of non-flow contributions are very important for STAR results are comparable with PHENIX results, except at high pT. At lowet pT v2 from Low Multiplicity subtraction is 35% lower than from template fit At intermediate pT they agree with each
STAR results are comparable with PHENIX ones.
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3) Small systems 3) Small systems
v2 in p+Au collisions without subtraction is larger than v2 in d+Au collisions that with subtraction for both methods. v2 in p+Au collisions from Low Multiplicity subtraction is lower than from template fit. STAR results are comparable with PHENIX results, except at high pT. The STAR data is clearly lower than PHENIX for pT>1.5 GeV/c
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3) Small systems 3) Small systems
Large difference between subtraction method and template fit v2 from subtraction method is negative at lower collision energies (different kinematics between near-side and away-side jet-like correlations?) v2 from template fit increases with collision centrality
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3) Small systems 3) Small systems
v2 becomes negative at high transverse momentum in d+Au collisions at low collision energy The correlation from away-side jet is stronger at high transverse momentum
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3) Small systems 3) Small systems
Large difference between v2 from two methods has been
subtraction in small systems. We do see similar v2 between p+Au and d+Au collisions for same multiplicity → v2 is not only driven by initial geometry. The integral v2 extracted by a template fit shows an universal trend as a function of <dN/dη> for different small systems at different energies → multiplicity plays an important role in small systems.
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3) Fixed target mode 3) Fixed target mode
Directed flow for identified particles agrees with AGS results.
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6) Hipertriton 6) Hipertriton