Post on 18-Aug-2021
Heavy Flavor and Quarkonia Measurements in Small Systems
Xuan Li (LANL)
RHIC&AGS2016 Xuan Li (LANL) 1
Outline
• MoFvaFon • Overview of RHIC and the LHC • Quarkonium producFon in p(d)+A collisions: – J/ψ, ψ’ and ϒ producFon.
• Heavy flavor producFon in p(d)+A collisions: – Semi-‐leptonic decay measurements. – B-‐hadron decayed J/ψ measurements.
• Summary and Outlook
RHIC&AGS2016 Xuan Li (LANL) 2
MoFvaFon • Heavy flavor producFon is a good probe to study the full
evoluFon of the medium as it is produced in the early stage of nuclear collisions due to its high mass (mc/mb>>ΛQCD). The heavy quark can traverse the whole evoluFon of the system as interacFons with the medium do not change the flavor.
• Quarkonia can break up when passing through the medium depending on the Fme spent inside the nucleus and interacFons with co-‐movers. Different kinemaFcs (x, Q2) can be probed by different bound states.
RHIC&AGS2016 Xuan Li (LANL) 3
D0
D0
J/ψ
K+
νl
νl
K-
e-/µ-
e+/µ+
e-/µ-
e+/µ+
Open Heavy Flavor producFon Heavy Flavor quarkonia producFon
Heavy flavor producFon in Heavy Ion Collisions
• Cold Nuclear Maber (CNM) effects: – Nuclear modificaFon of PDFs (shadowing,
anF-‐shadowing, EMC effect etc). – Cronin effect. – Energy loss of partons traversing the
nucleus (IniFal state). – Breakup of charmonium before exiFng
the nucleus. – Co-‐mover absorpFon.
• Hot nuclear maber effects: – Energy loss of partons traversing the QGP. – Color screening. – Coalescence of quarkonia in the QGP.
RHIC&AGS2016 Xuan Li (LANL) 4
• Need to measure mulFple observables in different processes to isolate the cold and hot nuclear maber effects.
• Need to invesFgate the CNM effects through the p(d)+A collisions.
• InteracFon with the medium is not well understood.
Why p(d)+Au collisions • Different x regions of the nuclear modified parton distribuFon
(nPDF) and different densiFes of the nuclear medium can be accessed by heavy flavor in different rapidity regions.
RHIC&AGS2016 Xuan Li (LANL) 5
-5 -4 -3 -2 -1 0 1 2 3 4 50
5
10
15
20
25
d/dch
dN
d
d + Au
200 GeV 0-20%
20-40%
40-60%
60-80%
80-100%
Min-bias
p A
y Forward Backward Mid-‐rapidity PoS DIS2013 (2013) 274
• Forward rapidity: • Small x region of the nuclear A PDF
probes shadowing effect. • Final state producFon spends shorter
Fme propagaFng through the nucleus in lower parFcle mulFplicity.
• Larger iniFal state parton energy loss.
Why p(d)+Au collisions
RHIC&AGS2016 Xuan Li (LANL) 6
p A
y Forward Backward Mid-‐rapidity
• Backward rapidity: • Large x region of the nuclear A PDF can
probe anF-‐shadowing effect. • Final state producFon spends longer Fme
propagaFng through the nucleus in higher parFcle mulFplicity.
• Smaller iniFal state parton energy loss. -5 -4 -3 -2 -1 0 1 2 3 4 5
0
5
10
15
20
25
d/dch
dN
d
d + Au
200 GeV 0-20%
20-40%
40-60%
60-80%
80-100%
Min-bias
PoS DIS2013 (2013) 274
• Different x regions of the nuclear modified parton distribuFon (nPDF) and different densiFes of the nuclear medium can be probed by heavy flavor in different rapidity regions.
Overview of RHIC and LHC • High luminosity data of various p(d)-‐nuclear collisions
which can create heavy flavor probes have been collected at RHIC and the LHC.
RHIC&AGS2016 Xuan Li (LANL) 7
RHIC LHC
Quarkonium producFon in p+A collisions
RHIC&AGS2016 Xuan Li (LANL) 8
• Are there any differences between different bound states of quarkonium inside the cold nuclear maber?
c c c cJ/ψ ψ’
bbΥ bb Υ’
J/ψ measurement in d+Au collisions at RHIC • Cronin effect (pT broadening) is observed for J/ψ measurements at PHENIX.
RHIC&AGS2016 Xuan Li (LANL) 9
• The <pT2> versus center of mass energy from the world data follows the same trend. Other CNM effect?
Phys. Rev. C 87, 034904 arXiv:1602.02212 [GeV]NNs
210 310
]2>
[(GeV
/c)
2 T<p
0
1
2
3
4
5
6
7
8
9
10STAR p+p 2009 |y|<1STAR+PHENIX d+Au 2008 |y|<1PHENIX p+p 2006 |y|<0.35PHENIX d+Au 2008 |y|<0.35NA38 NA51 NA50 p+pE789 p+Au
pCDF p+
ϒ measurements in d+Au collisions at RHIC
• Model including the gluon nPDF (shadowing), iniFal state parton energy loss and absorpFon by co-‐movers can reasonably describe the data.
• Possible suppression in which may be related with EMC effect?
• Need beber staFsFc data.
RHIC&AGS2016 Xuan Li (LANL) 10
ϒy
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
dAu
(1S+
2S+3
S) R
ϒ
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2 (1S+2S+3S)dAuSTAR R
STAR p+p Syst. UncertaintyPHENIXShadowing, EPS09 (Vogt)
)eEnergy Loss (Arleo, PeignEnergy Loss + EPS09
(b)
Phys. Rev. Leb. 109, 242301 (2012) Phys.Leb. B735 (2014) 127
d Au
J/ψ measurements in p-‐Pb collisions at ALICE (LHC) • Higher center of mass energy at LHC accesses lower x region.
Stronger cold nuclear maber effect (gluon saturaFon)?
RHIC&AGS2016 Xuan Li (LANL) 11
• Backward rapidity: no significant nuclear effects on J/ψ are observed.
• Mid and Forward rapidity: J/ψ suppression at low pT (pT<5 GeV/c). • Forward-‐y: largest suppression, RpPb increases with pT.
Backward-‐y (J/ψ→ μ+μ-‐) Mid-‐y (J/ψ→ e+e-‐)
Forward-‐y (J/ψ→ μ+μ-‐)
[JHEP 1506 (2015) 055]
p Pb
ϒ(1s) measurements in p-‐Pb collisions at LHC
RHIC&AGS2016 Xuan Li (LANL) 12
ALICE, Phys. Leb. B 740 (2015) 105, ATLAS-‐CONF-‐2015-‐050 ,LHCb, JHEP 07(2014)094
• ϒ(1S) RpPb has a comparable pT dependence with the prompt J/ψ RpPb in higher pT region (ATLAS) as expected.
• ϒ(1S) RpPb measured at LHC is generally consistent with unity in different rapidity regions.
• Does ϒ(1s) probes the shadowing or anF-‐shadowing region? More data.
• How about excited states?
Explore the CNM effect via ψ’ • Mid-‐rapidity ψ’ RdAu measured at PHENIX in d+Au collisions
has different trend and magnitude of suppression versus Ncoll from the J/ψ results.
RHIC&AGS2016 Xuan Li (LANL) 13
Number of binary nucleon-‐nucleon inelasFc collision
PRL 111, 202301 (2013)
• Similar iniFal state effect (shadowing, energy loss etc.) on J/ψ and ψ’.
• IndicaFon final state effects cause the difference.
• Can we study this in forward/backward rapidity and different collision systems?
RelaFve raFo of ψ’ to J/ψ VS rapidity • Centrality integrated relaFve raFo of ψ’ to J/ψ VS rapidity
for p+Au, p+Al and d+Au (mid-‐rapidity).
RHIC&AGS2016 Xuan Li (LANL) 14
• The J/ψ and ψ’ have similar suppression at forward rapidity. • Strong relaFve suppression is observed at back rapidity.
d Au/Al
Possible contribuFons to the differenFal suppression • Time spent inside the nucleus
– Longer Fme and path length spent by the cc-‐bar in Au-‐ (Al-‐) going direcFon than the p-‐ going direcFon.
• Co-‐movers absorpFon? – Charmonium can break up with the presence of co-‐movers. – Higher parFcle density in the Au-‐ (Al-‐) going direcFon may cause larger suppression.
RHIC&AGS2016 Xuan Li (LANL) 15
– According to the crossing Fme τ dependent model fit on world wide data (PRC 87 (2013) 054910), very small contribuFons.
– This effect can not explain the backward rapidity suppression.
RelaFve raFo of ψ’ to J/ψ VS rapidity • Centrality integrated relaFve raFo of ψ’ to J/ψ VS rapidity for p+Au, p+Al and d+Au (mid-‐rapidity).
RHIC&AGS2016 Xuan Li (LANL) 16
• Result is consistent within significant staFsFcal uncertainFes with co-‐mover dissociaFon model.
E. Ferreiro, PLB 749 (2015)
Comparison with the LHC results • Similar suppression trend for the rapidity dependence. More
suppression in LHC especially at forward rapidity?
RHIC&AGS2016 Xuan Li (LANL) 17
LHCb, QM15 ALICE, JHEP 12 (2014)
• Larger co-‐mover contribuFon at the LHC? Gluon saturaFon changes spectroscopic charmonium states?
JHEP 12 (2014) 073
Heavy flavor producFon in p(d)+A collisions
RHIC&AGS2016 Xuan Li (LANL) 18
Heavy flavor producFon
• Larger staFsFcs with higher background compared to quarkonium measurements.
• Flavor dependent energy loss via charm and bobom separaFon?
Open HF semi-‐leptonic decay in d+Au collisions at RHIC
• Forward rapidity: Similar suppression indicates similar iniFal state effects (shadowing, energy loss) for J/ψ and open charm producFon.
• Mid and Backward rapidity: Different trends between J/ψ and open heavy flavor. Final-‐state effects like co-‐mover absorpFon can not be neglected for J/ψ producFon.
RHIC&AGS2016 19 Xuan Li (LANL)
PRL 109, 242301 (2012), PRL 112, 252301 (2014)
d Au
Backward-‐y Mid-‐y Forward-‐y
Open HF semi-‐leptonic decay in d+Au collisions at RHIC
• Forward rapidity: Similar suppression indicates similar iniFal state effects (shadowing, energy loss) for J/ψ and open charm producFon.
• Mid and Backward rapidity: Different trends between J/ψ and open heavy flavor. Final-‐state effects like co-‐mover absorpFon can not be neglected for J/ψ producFon. Enhancement of open heavy flavor can be explained by incoherent mulFple scabering which gives the Cronin type behavior.
RHIC&AGS2016 20 Xuan Li (LANL)
d Au
Mid-‐y Forward-‐y
Phys. Lett. B 740 (2015) 23
PRL 109, 242301 (2012), PRL 112, 252301 (2014)
Backward-‐y Mid-‐y
Open HF semi-‐leptonic decay in p+Pb collisions at LHC
• Forward and mid rapidity: RpPb consistent with unity. • Backward rapidity: slightly larger than unity for 2 < pT < 4
GeV/c. • Data described within uncertainFes by models including
shadowing, incoherent/coherent mulFple scabering and kT broadening.
RHIC&AGS2016 Xuan Li (LANL) 21
Phys. Leb. B 754 (2016) 81-‐93
Forward-‐y Backward-‐y Mid-‐y
p Pb
B-‐hadron decayed J/ψ measured in p+Pb collisions at LHC
• No significant suppression or enhancement for the kinemaFcs range of |y*| < 1.5 and 10 <pT< 30 GeV.
• No indicaFon of significant cold nuclear maber effects. • What about the low pT region? RHIC&AGS2016 Xuan Li (LANL) 22
ATLAS-‐CONF-‐2015-‐023
p Pb
B-‐meson decayed J/ψ measurements at RHIC
RHIC&AGS2016 Xuan Li (LANL) 23
• The B-‐meson decayed J/ψ fracFon does not have the center of mass energy dependence for J/ψ pT < 5GeV/c region.
(GeV/c)T
pψInclusive J/0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
frac
tion
ψB
to J/
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
fractionψRun12 510 p+p B to J/
) collisionsp fraction in p+p (ψB to J/
=510 GeV 1.2<|y|<2.2NNsPHENIX p+p
=1.96 TeV |y|<0.6NNs pCDF p+
=7 TeV |y|<0.9NNsALICE p+p
=7 TeV 1.6<|y|<2.4NNsCMS p+p
=13 TeV 4.0<y<4.5NNsLHCb p+p
fractionψRun12 510 p+p B to J/
PH ENIXpreliminary
B-‐meson decayed J/ψ measurements at RHIC
RHIC&AGS2016 Xuan Li (LANL) 24
• No center of mass dependence of B-‐meson decayed J/ψ fracFon in the p+p baseline measurement.
• Suppression of nuclear modificaFon factor measured in 200 GeV Cu+Au collisions is found.
• Analysis in p+A data is ongoing.
(TeV)NNsCenter of mass energy -110 1 10
frac
tion
ψB
to J
/
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
fractionψRun12 510 p+p B to J/
) collisionsp fraction in p+p (ψB to J/
=510 GeV 1.2<|y|<2.2NNsPHENIX p+p
=1.96 TeV |y|<0.6NNs pCDF p+
=7 TeV |y|<0.9NNsALICE p+p
=7 TeV 1.6<|y|<2.4NNsCMS p+p
=13 TeV 4.0<y<4.5NNsLHCb p+p
fractionψRun12 510 p+p B to J/
PH ENIXpreliminary
2012 200 GeV Cu+Au collisions
Summary • Shadowing, coherent parton energy loss and the co-‐mover absorpFon models can describe the J/ψ and ϒ RdAu results at RHIC.
• Shadowing and energy loss models are in fair agreement with J/ψ measurements at the LHC. Weak CNM effect on ϒ(1s) measured at the LHC.
• DifferenFal suppression of ψ’ to J/ψ relaFve raFo measured at PHENIX in p+Al and p+Au data show strong evidence of final state effects. Further suppression of ψ’ to J/ψ relaFve raFo is seen at the LHC.
• Rapidity dependent nuclear modificaFon of open heavy flavor is found at RHIC. Smaller CNM effects are observed at the LHC.
RHIC&AGS2016 Xuan Li (LANL) 25
RHIC&AGS2016 Xuan Li (LANL) 26
Outlook
• Large p(d)+A data sets in various center of mass energy collected at RHIC and the LHC provide opportuniFes to study – Quarkonia (J/ψ, ψ’, ϒ... ) measurements with beber precision to understand not only the iniFal state but also the final state CNM effects.
– Measurements of B-‐hadron decayed J/ψ and D/B separated single elecFons/muons in p+A collisions with higher staFsFcs will verify the flavor dependent energy loss in cold nuclear maber.
• More results to come to improve the understanding of cold nuclear effects.
Backup
RHIC&AGS2016 Xuan Li (LANL) 27
J/ψ measurement in d+Au collisions at RHIC
RHIC&AGS2016 Xuan Li (LANL) 28 Phys. Rev. Leb. 98, 232301 (2007)
• J/ψ producFon at 200 GeV is dominated by gluon fusion. Data provide a constraint on the gluon nPDF in the accessed x region.
• Gradual increasing with pT in all rapidiFes, which is consistent with Cronin effect.
• Overall suppression of RdAu is rapidity dependent.
Backward rapidity
Mid rapidity
Forward rapidity
The Forward Vertex Detector (FVTX)
RHIC&AGS2016 Xuan Li (LANL) 29
Sensor HDIHDI
FPHX Chips (13 per column)
Mini-strips are oriented to approximate an arc
! Sensor" 2 columns of strips" 1664 strips per column" strip length 2.8 to 11.2 mm" 75 micron spacing" 48 wedges per disk (7.5˚/
sensor, 15˚/wedge)" 0.5 mm overlap with adjacent
wedges
! FPHX Chip" 1 column readout" 128 channels " ~ 70 microns channel spacing" Dimensions –9mm x 1.2 mm
Forward J/ψ and ψ’ measurement in p+p collision • With improved mass resoluFon provided by FVTX, clear J/ψ
and ψ’ idenFficaFon via di-‐muon channel (1.2<|y|<2.2) in run15 200 GeV p+p data.
RHIC&AGS2016 Xuan Li (LANL) 30
• The forward ψ’ to J/ψ raFo measured in p+p collisions is consistent with the global data.
p p
How about asymmetric nuclear collisions? • In 200 GeV p+Al collisions.
RHIC&AGS2016 Xuan Li (LANL) 31
p Al
• Even with raw data, clearly the ψ’ yield is suppressed relaFve to J/ψ in the Al going direcFon.
How about asymmetric nuclear collisions? • In 200 GeV p+Au collisions.
RHIC&AGS2016 Xuan Li (LANL) 32
p Au
• Even with raw data, clearly the ψ’ yield is suppressed relaFve to J/ψ in the Au going direcFon as well.
p+A pT dependence
Xuan Li (LANL) 33
Low pT, backwards rapidity ψ(2s) yields consistent with ZERO.
RHIC&AGS2016
Overview of the PHENIX detector • The newly installed silicon vertex detectors: VTX(since 2011) and
FVTX(since 2012) make the new heavy flavor measurement possible in p+p, p+Al, p+Au, Cu+Au and Au+Au collisions.
• VTX: – With |y|<1.2 and φ≈2π coverage. – provide precise vertex and tracking
measurements for D,BàX+e.
RHIC&AGS2016 Xuan Li (LANL) 34
• FVTX: – With 1.2<|y|<2.2 and φ=2π coverage. – provide precise tracking and improved di-‐
muon mass resoluFon measurements for J/ψ, ψ’ àμ+μ,-‐BàJ/ψ and D, B separaFon.
MuTr:1.2<|y|<2.2, φ=2π
MuID:1.2<|y|<2.2, φ=2π
p, Cu, Au
p, Au, Al
Can we measure B meson in forward rapidity? B-‐>J/ψ-‐>μ+μ-‐
RHIC&AGS2016 Xuan Li (LANL) 35
J/ψ
Prompt hadron
μ+
μ-‐
J/ψ
B
μ+
μ-‐
DCA
DCA R
// z
FVTX
Tracks from decayed parFcles have asymmetric projecFon.
• B mesons measured in the forward/backward rapidity with longer decay length may probe different QGP evoluFon stage in heavy ion collisions from the mid-‐rapidity region.
• Different DCAR shapes of prompt parFcles and decayed parFcles make the separaFon of B decayed J/ψ and prompt J/ψ feasible.