transverse single spin asymmetries at large …1...transverse single spin asymmetries at large...

TransversesinglespinasymmetriesatlargeFeynmanxintheSTARexperiment

atRHICMrigankaMouliMondal(fortheSTARCollaboraAon)

InsAtuteofPhysics,Bhubaneswar

LightCone2017,MumbaiUniversity,India

Outline

² TransverseSingleSpinAsymmetries² TheSTARexperimentandForwardMesonSpectrometer(FMS)

² EM-JetsinforwardandcentralrapidityandANmeasurementsatRHICRun11at√s=500GeV

² STARForwardUpgrades

20/09/2017 LightCone2017,MumbaiUniversity,India 2

π0ANMeasurementsatForwardRapidity

22

No indication of falling AN

as pT

as opposed to twist-3 expectations

π0 AN vs p

T

Forward rapidity hadron production

isolation cones

²  RisingANwithxF²  ANnearlyindependentof√s

TransverseSingleSpinAsymmetry

Inclusiveπ0produc9on

xF=2pZ/√s


A N

SiversandCollinseffect

}

TABLE VIII Experimental access to the leading twist TMD distributions in SIDIS with unpolarized (U), longitudinally (L)or transversely polarized (T) beam (modulation first subscript) and/or target (modulation second subscript).

Modulation Combination√s Target Observed Measurement

Distribution name GeV type hadron types

sin(φ+ φS)UT h1 ⊗H⊥1 18 d h±, π±,K±,K0 Ageev et al. (2007) and Alekseev et al. (2009a)

Transversity p h± Adolph et al. (2012b) and Alekseev et al. (2010b)

p π±,K± prelim. Pesaro (2011)

7.4 p π±,π0,K± Airapetian et al. (2005b, 2010a)

3.5 n π± Qian et al. (2011)

sin(φ− φS)UT f⊥1T ⊗D 18 d h±, π±,K±,K0 Ageev et al. (2007) and Alekseev et al. (2009a)

Sivers p h± Adolph et al. (2012c) and Alekseev et al. (2010b)

p π±,K± prelim. Pesaro (2011)

7.4 p π±,π0,K± Airapetian et al. (2005b, 2009b)

3.5 n π± Qian et al. (2011)

cos(2φ)UU h⊥1 ⊗H⊥

1 18 d h± prelim. Sbrizzai (2011)

Boer-Mulders 7.4 p π±,K± Airapetian et al. (2012a)

3.5 n π+ Osipenko et al. (2009)

sin(3φ− φS)UT h⊥1T ⊗H⊥

1 18 d h± prelim. Kotzinian (2007)

Pretzelosity 18 p h± prelim. Parsamyan (2011)

7.4 p π±,K± prelim. Pappalardo (2010)

sin(2φ)UL h⊥1L ⊗H⊥

1 18 d h± Alekseev et al. (2010a)

Worm-gear 1 7.4 p π±,π0 Airapetian et al. (2000b, 2001)

d π±,π0,K+ Airapetian et al. (2003)

3.5 n π±,π0 Avakian et al. (2010)

cos(φ− φS)LT g⊥1T ⊗D 18 d h± prelim. Kotzinian (2007)

Worm-gear 2 18 p h± prelim. Parsamyan (2011)

7.4 p π±,π0,K± prelim. Pappalardo and Diefenthaler (2011)

3.5 n π± Huang et al. (2012)

fect from COMPASS and HERMES. The Sivers, Collins,worm-gear and pretzelosity effects are all consistent withzero in the deuteron target data. The Collins and Siverseffects observed in the proton data therefore contain apredominant isovector contribution.We next focus on the Sivers, Boer-Mulders and Collins

effects.

1. The Sivers and Boer-Mulders TMD distributions

The Sivers distribution was first proposed in Sivers(1990) in an attempt to explain the large transverse sin-gle spin asymmetries observed in the 1970s and 1980s. Itdescribes the correlation between the transverse momen-tum kt of the struck quark and the spin S and momentump of its parent nucleon

fq/p↑(x, kt) = f q1 (x, k

2t )− f⊥q

1t (x, kt)S · (kt × p̂)

M. (36)

The kt dependence means that the Sivers distribution issensitive to non-zero parton orbital angular momentum

in the nucleon, though the mapping from Sivers observ-ables to quark (and gluon) orbital angular momentum is(so far) model dependent with present theoretical tech-nology.

The Sivers distribution has the interesting propertythat it is odd under time reversal. Due to this fea-ture, such a correlation was believed to be forbiddenfor more than a decade. Then Brodsky et al. (2002a,b)showed that, with initial- or final-state interactions, theSivers effect could be non-zero in QCD processes. Final-state interactions in SIDIS can generate the azimuthalasymmetry before the quark fragments into hadrons.Shortly afterwards, Collins (2002) realized that initial-state color interactions in the case of Drell-Yan and final-state interactions in the case of SIDIS would lead toa process-dependent sign difference in the Sivers dis-tribution. SIDIS measurements (Adolph et al., 2012c;Airapetian et al., 2005b, 2009b; Alekseev et al., 2010b;Pesaro, 2011; Qian et al., 2011), suggest sizable asymme-tries at the level of about 5−10% for a proton and a neu-tron target, while Drell-Yan measurements are plannedfor the future.

32

Siverseffect:thecorrelaAonbetweenthetransversemomentum(kt)ofthestruckquarkandthespin(S)andmomentum(p)ofitsparentnucleon

Sktp

Siversdistribu9on

Collinseffect:spin-momentumcorrelaAoninthehadronizaAonprocess

0

0.1

0.2

0

0.1

0.2

0.2 0.4 0.6 0.8

A 12

0.2 < z1 < 0.3

AUL

AUC

0.3 < z1 < 0.5

z2

A 12

0.5 < z1 < 0.7

z2

0.7 < z1 < 1

0.4 0.6 0.8

FIG. 20 Collins asymmetry for the double ratios of like-sign(L), unlike-sign (U) and any charged (C) pion pairs fromBelle (Seidl et al., 2008). AUL and AUC are sensitive to dif-ferent combinations of the favored and unfavored Collins frag-mentation functions. The bands indicate the systematic un-certainties.

2. The Collins TMD fragmentation function

The Collins TMD fragmentation function describes aspin-momentum correlation in the hadronization process,sq · (kq × pt), with a hadron produced in fragmentationhaving some transverse momentum pt with respect to themomentum direction k of a transversely polarized frag-menting quark with spin sq (Collins, 1993; Collins et al.,1994). The Collins fragmentation function has beeninvestigated in semi-inclusive lepton-nucleon scatteringand e+e− annihilation. The magnitude of the effect is ap-proximately 5–10%, like that found for the Sivers asym-metries.For e+e− annihilation the chiral-odd Collins fragmen-

tation function enters with a second Collins function inthe opposing jet. The Collins function has been measuredto be non-zero for the production of charged pions ine+e− annihilation at Belle (Abe et al., 2005; Seidl et al.,2008), as shown in Fig. 20, and in recent preliminary datafrom BABAR (Garzia, 2012).In SIDIS the second chiral-odd function is the transver-

sity distribution introduced in Section II and dis-cussed further below (or the Boer-Mulders distribu-tion). The HERMES (Airapetian et al., 2005b, 2010a),COMPASS (Adolph et al., 2012b; Ageev et al., 2007;Alekseev et al., 2009a, 2010b; Pesaro, 2011) and JLabHall A (Qian et al., 2011) experiments have performedSIDIS measurements of the Collins effect. The measure-ments for a proton target are shown in Figs. 21 and 22

−0.05

0

0.05

10−1 0.2 0.4 0.6x

Asin(φ

+ φ

S) U

T

HERMESπ+

π−

z pTh (GeV)0.5 1

FIG. 21 Collins amplitudes for charged pions measuredby HERMES with a proton target; from Airapetian et al.(2010a). The inner error bar represents the statistical un-certainty; the full bar the quadratic sum of statistical andsystematic uncertainties.

for HERMES and COMPASS respectively. (Note thatCOMPASS uses a definition of the Collins angle whichresults in Collins amplitudes with opposite sign to the“Trento convention” of Bacchetta et al. (2004) used byHERMES, JLab and commonly in theoretical papers).There is excellent agreement between the measurementsin similar kinematics. One finds the striking observationthat the Collins amplitude for π− is of similar size to π+

production but comes with opposite sign. This hints atan unfavored Collins function of similar size and oppositesign than the favored one, a situation very different fromthat observed with unpolarized fragmentation functions.

COMPASS 2010 proton data

x−2

10−1

10

p Coll

A

−0.1

−0.05

0

0.05

z0.5 1

positive hadronsnegative hadrons

(GeV)hTp0.5 1

FIG. 22 Collins amplitudes for unidentified charged hadronsmeasured by COMPASS with a proton target (Adolph et al.,2012b). The hadron yield is dominated by pions. Note that adifferent definition of the Collins angle results in amplitudeswith the opposite sign compared to other measurements. Thebands indicate the systematic uncertainties.

3. Probing transversity

The transversity distribution introduced in Section IIdescribes the transverse polarization of quarks within atransversely polarized nucleon. Along with the unpolar-ized and helicity distributions, it survives integration overpartonic transverse momentum and is thus a collineardistribution.The first moment of the transversity distribution is

proportional to the nucleon’s C-odd tensor charge, viz.

34

Scaberedquarku

du uu

X

u

π0,ηπ±,k±

FragmentaAon,ΔDhq

sq=spinofthefragmenAngquarkkq=momentumdirecAonofthequarkpt=transversemomentumofhadronwithrespecttothedirecAonofthefragmenAngquark

ptsq

D. Sivers, Phys. Rev. D 41, 83 (1990) J.C.Collins,Nucl.Phys.B396,161(1993)

SensiAvetoprotonspin-partontransversemo.oncorrelaAons

SensiAvetotransversity(δq)

20/9/2017 SeminaratIOP,Bhubaneswar,India 4

SeparaAngSiversandCollinseffects

needtomovebeyondinclusiveproducAon

•  Siverseffect:FullJets,Directphotons,Drell-Yan•  Collinseffect:azimuthalorienta9onofpar9cleswithinajet

)(),( 21 zDkxf h

qqT ⋅∝ ⊥⊥

Siversdistribu9on

),()( 221 ⊥

⊥⋅∝ kzHxqδ

CollinsFFQuarktransversespindistribu9on

AN= +

Observedtransversesingle-spinasymmetriesofinclusivehadronscouldarisefromtheSiverseffectorCollinseffect,orfromalinearcombina9onofthetwo

20/09/2017 SeminaratIOP,Bhubaneswar,India 5

RHIC:theworld’sfirstandonlypolarizedprotoncollider

Beams: √s 62.4 - 500 GeV pp

AGSLINACBOOSTER

PolarizedSource

200MeVPolarimeter

HydrogenJetPolarimeter

PHENIXSTAR

SiberianSnakes

SiberianSnakes

SpinFlipper

CarbonPolarimeters

RFDipole AGSInternalPolarimeter

AGSpCPolarimeter

StrongSnake

TuneJumpQuadsHelicalParAalSnake

SpinRotators

For2011:AverageBlueBeamPolariza9on=51.6%(Transverse)Luminosity=22pb-1


20/09/2017

FPD EM Calorimeter Small cells onlyTwo 7x7 arrays

FMSPbGlassEMCalorimeterpseudo-rapidity2.5<η<4.0Smallcells:Outercells:3.81x3.81cm5.81x5.81cm

ForwardECALinSTAR

LightCone2017,MumbaiUniversity,India 7

PhotonsinFMSTowersàClustersàPhotoncandidates(photons)

(showershapefits)

ForwardMesonSpectrometer(FMS)-2011:--PbglassEMcalorimetercovering2.5<η<4.0--Detect𝜋0,η,directphotonsandjet-likeeventsinthekinemaAcregionwheretransversespinasymmetriesareknowntobelarge.

EM-JetcharacterisAcs

20/09/2017

htempEntries 187224Mean 3.536RMS 1.771

no. photons0 2 4 6 8 10 12 140

10000

20000

30000

40000htemp

Entries 187224Mean 3.536RMS 1.771

nTowersj {energyj>60&&energyj<80}

EM-Jet Energy 60-80 GeVhtemp


aam0 0.2 0.4 0.6 0.8 10

500

1000

1500

2000

2500

3000

3500 htempEntries 29185Mean 0.2655RMS 0.19

mS {energyj>60&&energyj<80&&zgg<.8&&nTowersj==2}

EM-Jet Energy 60-80 GeV<0.8, no. phootns = 2aaZ

²  2-photonjetsaremostlyπ0

²  Eventswithmorethan2photonsshowjet-likeenergyflowγγinvariantmass2-photonEM-jets

dE/d(ΔR)distribuAonofEM-Jets

EM-JetEnergy60-80GeVZγγ<0.8,no.photons=2

#Jets

2-photonEntries 138843Mean 0.06152RMS 0.09392R)

(arb

itrar

y sc

ale)

6dE

/d(

2-photonEntries 138843Mean 0.06152RMS 0.09392



6-photonEntries 522345Mean 0.1566

RMS 0.1049

0 0.2 0.4 0.6 0.8 1

6-photonEntries 522345Mean 0.1566

RMS 0.1049




0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1



)jet,photonsR6d(0 0.2 0.4 0.6 0.8 1


dE/d(ΔR)(arbitraryscale)

p+p√s=500GeVtransversedatasetsJetalgorithm:anA-ktR-parameter:0.7pTEM-Jet

>2.0GeV/cphotonswithpT>0.001GeV/cLeadingEM-Jets:MulA-photonJetswithhighestenergy2.8<ηEM-Jet<4.040GeV<EnergyEM-Jet<100GeV


ANvs.EM-JetEnergy

20/09/2017

²  Isolatedπ0’shavelargeasymmetriesconsistentwithpreviousobservaAon(CIPANP-2012StevenHeppelmann)

hbps://indico.triumf.ca/contribuAonDisplay.pycontribId=349&sessionId=44&confId=1383

²  Asymmetriesforjetswithphotons>2eventsaremuchsmaller

EM-Jet Energy (GeV)40 50 60 70 80 90

NA

0

0.02

0.04

> 0)F

-Jets (x0/

<0)F

-Jets (x0/

> 0)F

EM-Jets (x

< 0)F

EM-Jets (x

> 0)F

>0.3 (xaa

2-photon-Jets-m

Graph

= 500GeVs @ Bp+p > 2.0 GeV/c

TEMJetp

< 4.0EMJetd2.8 <

STAR Preliminary π0-Jets–2γ-EM-Jetsmγγ<0.3Zγγ<0.82γ-EM-Jets(η+con9nuum)–mγγ>0.3EM-Jets–photons>2


Isolatedπ0:I)  reconstructedπ0for2-photonjetII)  nophotonwithinphysicalcone(eg.

70mR)ofreconstructedπ0

ANfordifferent#photonsinEM-Jets

20/09/2017

NA

0

0.05

0

0.05

0

0.05

0

0.05

2 3 4 5 6

0

0.05 > 0Fx < 0Fx

STAR Preliminary

2 4 6 8

(GeV/c)TEMJet p

4 6 8

EM-Jet Energy = 40-60 GeV 60-80 GeV 80-100 GeV no. photons = 1 2 3 4 5

²  1-photonevents,whichincludealargeπ0contribuAoninthisanalysis,aresimilarto2-photonevents

²  Three-photonjet-likeeventshaveaclearnon-zeroasymmetry,butsubstanAallysmallerthanthatforisolatedπ0’s

²  ANdecreasesastheeventcomplexityincreases(moreparAclesinjets)

²  ANfor#photons>5issimilartothat#photons=5


ANforcorrelatedcentraljetsandnocentraljetcases

20/09/2017

NA

0

0.05

0.1

<4.0EMJet forwardd2.8 <

< 2.0EMJet centrald-1.0 < > 2.0 GeV/cEMJet central

Tp

0

0.05

0.1

no central EM-Jet central EM-Jet

/2)/<3q6/2)</(

3 4 5 60

0.05

0.1

STAR Preliminary

3 4 5 6 7

0.06

3 4 5 6 7

(GeV/c)EM-JetT

p

EM-Jet Energy = 40-60 60-80 80-100 GeV

3-photon >3-photon 0

/isolated-

²  Asymmetriesfortheforwardisolatedπ0arelowwhenthereisacorrelatedaway-sidejet.


JETsatcentralrapidity•  EMJetsare

reconstructedinmidrapidityBEMC+EEMC,-1.0<ηEM-

Jet<2.0•  BacktobackΔφ

relaAonsusedtofindifthereisanyassociatedjets

2à2partonscabering

ANforπ0andCollinsasymmetriesofπ0


January 30, 2015 22:33 WSPC/INSTRUCTION FILE S3˙Pan

TSSA of Forward π0 at STAR 3

/ GeVγγM0.05 0.1 0.15 0.2 0.25 0.30

5000

10000

15000

20000

25000datacombined fit

signal0πbackground

= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

< 43.0 GeV, Fill15419γγ 38.0 GeV < EγγM

Fig. 1. Distribution of di-photon mass with 38 GeV < Eγγ < 43 GeV, 2.8 < η < 4.0 and energysharing Zγγ < 0.8 (Zγγ = |E1 − E2|/Eγγ). Grey area: signal region; Shaded area: sidebands.

by QCD theory in which π0 emerges as a result of 2 → 2 partonic hard-scattering73

there must be other potential sources that generate the observed isolated π0 with74

large asymmetries. But it should be pointed out that here the reconstructed jet75

is only the electromagnetic component of the full jet. In the future with forward76

detector upgrades at STAR a full jet reconstruction will be possible.77

Fx0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32 0.34

NA

-0.01

0

0.01

0.02

0.03

0.04

0.05

> 0F x0πinclusive

< 0F x0πinclusive

5.2% beam pol. scale uncertainty not shown

= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

Fx0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32 0.34

NA

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06 > 0F x0πinclusive

> 0F x0πisolated < 0.9

EM in jet, Z0π


= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

Fig. 2. Left: inclusive π0 transverse single spin asymmetries vs xF . Right: compare inclusive π0

AN vs isolated and non-isolated π0 AN .

The pT dependence of inclusive π0 AN can also be used to test theory predictions,78

e.g. from twist-3 expectations AN will always decrease with increasing pT due to79

the nature of higher twist terms. Figure 3 shows AN vs pT for inclusive and isolated80

π0 from two xF bins.81


4 Yuxi Pan, for the STAR Collaboration

/ GeVT

p2 3 4 5 6 7 8

NA

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

< 0.32F 0.24 < x0πinclusive

< 0.32F 0.24 < x0πisolated


= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

/ GeVT

p3 4 5 6 7 8 9

NA

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

< 0.40F 0.32 < xNinclusive A

< 0.40F 0.32 < xNisolated A


= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

Fig. 3. Inclusive π0 AN vs pT . Left: 0.24 < xF < 0.32, Right: 0.32 < xF < 0.40.

2.3. Sivers/Collins asymmetries of jet-like events and π0 in jets82

In the transverse momentum dependent framework the observed asymmetries are83

generated through the Sivers5 and Collins6 mechanism. These theories describe84

processes which involve two scales such as di-jet asymmetries7 and azimuthal asym-85

metries of hadrons within jet8. It has been shown that the Sivers function is related86

to twist-3 parton distribution function via an integral relation3, and there exists87

a similar relation between Collins function and twist-3 fragmentation functions2.88

With the same dataset STAR has measured asymmetries of forward EMjets and π089

azimuthal asymmetries within the EMjet.90

Fig. 4. AN of EMjets containing different number of photons.

Figure 4 shows AN of EMjet constructed by applying anti-kT algorithm with91

R = 0.7 on FMS photons. The asymmetries are plotted for jets having only two92

•  π0isreconstructedfromFMS•  Collinsasymmetriesofπ0relaAvetojetaxisisbeingmeasured

20/09/2017


TSSA of Forward π0 at STAR 3

/ GeVγγM0.05 0.1 0.15 0.2 0.25 0.30

5000

10000

15000

20000

25000datacombined fit

signal0πbackground

= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

< 43.0 GeV, Fill15419γγ 38.0 GeV < EγγM

Fig. 1. Distribution of di-photon mass with 38 GeV < Eγγ < 43 GeV, 2.8 < η < 4.0 and energysharing Zγγ < 0.8 (Zγγ = |E1 − E2|/Eγγ). Grey area: signal region; Shaded area: sidebands.

by QCD theory in which π0 emerges as a result of 2 → 2 partonic hard-scattering73

there must be other potential sources that generate the observed isolated π0 with74

large asymmetries. But it should be pointed out that here the reconstructed jet75

is only the electromagnetic component of the full jet. In the future with forward76

detector upgrades at STAR a full jet reconstruction will be possible.77

Fx0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32 0.34

NA

-0.01

0

0.01

0.02

0.03

0.04

0.05

> 0F x0πinclusive

< 0F x0πinclusive


= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

Fx0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32 0.34

NA

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06 > 0F x0πinclusive

> 0F x0πisolated < 0.9

EM in jet, Z0π


= 500 GeVs + X @ 0π + p -> ↑p

STAR Preliminary

Fig. 2. Left: inclusive π0 transverse single spin asymmetries vs xF . Right: compare inclusive π0

AN vs isolated and non-isolated π0 AN .

The pT dependence of inclusive π0 AN can also be used to test theory predictions,78

e.g. from twist-3 expectations AN will always decrease with increasing pT due to79

the nature of higher twist terms. Figure 3 shows AN vs pT for inclusive and isolated80

π0 from two xF bins.81

•  Isolatedπ0 tendtohavesignificantly largerasymmetries thanπ0associatedwithjetacAviAesinthevicinity.

•  Sivers (EM-Jets) and/or Collins (π0 relaAve to jet axis) asymmetries areinsufficienttoaccountfortheobservedinclusiveπ0singlespinasymmetries.

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.....

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......

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.

Backup

.. Backup -Inclusive π0 AUT and background asymmetries

4 / 7

Fx0.15 0.2 0.25 0.3 0.35 0.4 0.45

)Hφ

- Sφsin

(U

TA

-0.01

0

0.01

0.02

0.03

0.04

0.05)

Hφ -

Sφsin(

UTA

background asymmetry


> 2 GeVjetT

p

< 4.0jetη2.8 <

< 0.9EM0 < Z

= 500 GeVs + X @ 0π + p -> jet + ↑p

anti-kT R = 0.7STAR Preliminary

EMZ0.3 0.4 0.5 0.6 0.7 0.8 0.9

)Hφ

- Sφsin

(U

TA

-0.01

0

0.01

0.02

0.03

0.04

0.05)

Hφ -

Sφsin(

UTA

background asymmetry


> 2 GeVjetT

p

< 4.0jetη2.8 <

= 500 GeVs + X @ 0π + p -> jet + ↑p

anti-kT R = 0.7STAR Preliminary


ANforπ0andCollinsasymmetriesofπ0

SummaryandOutlook²  Jetswithisolatedπ0havelargeasymmetry.²  ANdecreasesastheeventcomplexityincreases.²  Isolatedπ0asymmetriesaresmallerwhenthereisacorrelatedEM-jet

atmid-rapidity.Largeforwardπ0AN:Comesfrom2à2partonscaberingwithsomecontribu9onfromdiffrac9veevents?²  Sivers(EM-Jets)and/orCollins(π0relaAvetojetaxis)asymmetriesare

insufficienttoaccountfortheobservedinclusiveπ0singlespinasymmetries.


q 2015:installaAonofFMS-PreshowerandRomanpots-p+p200GeVlongitudinal&transversep↑+Au/Al200GeVtransverse,Spineffectsindiffrac9on

q 2017:installaAonofFMS-Postshower-p+p510GeVtransverseANforDellYan,directphotons

²  2017:post-showerdetector

ForwardUpgrade(≧2021)Overview

15

Requirements:Ø  wideacceptancemid-rapiditydetectorwithgoodPID(p,K,p)Ø  forwardrapidi9es(1.0<η<4.5)Ecal+HCal+chargeiden9fica9on

ForwardrapidiAes

•  2.5<η<4.5PreshowerdetectorEMcalorimeter•  PHENIXPbScHadroniccalorimeter•  L=4λl4-6addiAonallayersofSiliconMicrostripand/orsmall-stripThinGapChamber

backup


FMS-Jets BEMC+EEMC-Jets

EM-Jet/offAxispT(GeV/c)EM-Jet/offAxispT(GeV/c)

FMS-Jets BEMC+EEMC-Jets

EM-Jet/offAxispT(GeV/c)EM-Jet/offAxispT(GeV/c)

Sun Jan 10 22:25:42 2016

Energy Jet0 50 1000

05

0.1

Pt Jet0 5 10 15 200

05

0.1

15

0.2

h12h12

Jetd2.5 3 3.5 4 4.50

05

0.1

h13h13

Jetq-2 0 2

0

05

0.1h14h14

x F Jet0 0.2 0.4 0.6 0.8 10

05

0.1

15

0.2h15h15

#photons Jet0 5 10 150

0.1

0.2

h16h16

JetaR0 0.5 1 1.5 20

0.2

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0.6

h17h17

in JetaaSig0 5 10 150

0.1

0.2

0.3

0.4h18h18

m0 0.5 1 1.5 20

05

0.1

15

h19h19

z0 0.2 0.4 0.6 0.8 10

05

0.1

15

h110h110

E0 50 1000

0.1

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pT0 5 10 15 200

0.2

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h112h112

d2.5 3 3.5 4 4.50

0.1

0.2

0.3

h113h113

q-2 0 20

05

0.1h114h114

in JetaaBkd0 5 10 150

0.1

0.2

0.3

0.4h115h115

m0 0.5 1 1.5 20

05

0.1

15

h116h116

z0 0.2 0.4 0.6 0.8 10

05

0.1

15

0.2

h117h117

E0 50 1000

0.1

0.2

pT0 5 10 15 200

0.2

0.4

h119h119

d2.5 3 3.5 4 4.50

0.1

0.2

h120h120

q-2 0 20

05

0.1

15

0.2

h121h121

NLS}aaE L/E {0 0.2 0.4 0.6 0.8 10

0.1

0.2

0.3

h122h122

}aaj T {0 0.2 0.4 0.6 0.8 10

0.1

0.2

0.3

h123h123

H NLSq-2 0 2

05

0.1

15

h124h124

E0 50 1000

0.5

1

pT0 5 10 15 200

0.5

1

1.5

2

h126h126

d2.5 3 3.5 4 4.50

0.1

0.2

0.3

0.4

h127h127

q-2 0 2

0.1

0.2

h128h128

Data%

+%MC%

Main%purpose%of%simulaGons%%

JP2%

•  Understanding%FMS%data%with%full%PYTHIA%simulaGons%with%standard%STAR%framework.%

•  Construct%the%matrix%%-%#true%photon%vs.%#photons%detected%:%This%would%be%used%for%

correcGng%%AN,EM-Jets

%of%a%certain%n-photon-class%from%the%effect%of%probability%

misidenGfying%to%the%other%%%n-photon-clases%

#photons%in%Jets%in%MC%and%data%was%not%matching%:%%

%%%%%%1.%AVenuaGon%was%not%there%in%GEANT%energy%deposiGon%mode.%%GEANT%is%used%with%

an%aVenuaGon%factor.%%%%%

%%%%%%2.%PYTHIA6%is%not%tuned.%Specially,%there%is%no%scope%to%include%%hard%diffracGon.%

#photons%in%Jets%

1/26/16% 5%STAR%CollaboraGon%MeeGng,%BNL%2.PYTHIAtunedependenciesarechecked:HarddiffracAonnotincurrentscopeofPYTHIA6

DatapointcorrecAonsandbeberunderstandingDetectorwithGEANTsimulaAons


The Relativistic Heavy Ion Collider

PHENIX STAR

Brhams pp2pp

Au+Au + Cu+Au

Polarized p+p, d+Au Polarized p + Au

RHIC is a QCD lab

20/09/2017

1)Heavy-ionProgram--StudymediumproperAes,EoS--pQCDinhotanddensemedium2)  RHICbeamenergyscan--searchofcriAcalpoint--chiralsymmetryrestoraAon1)  Longitudinalandtransversespinprograms--StudyprotonintrinsicproperAes2)  Forwardprogram--spinstructureofproton--Studyoflowxproper/esandsearchforCGCTaggedforwardphysics--StudyelasAcandinelasAcprocesses--InvesAgategluonicexchangesandsearchforgluonicmaber

RHICPhysicsFocus


TSSA–twotheoreAcalframework

20/09/2017

Sivers fct.

Spin-dependenttransversemomentumdependent(TMD)func9onST.(PxkTBrodsky,Hwang,Schmidt,02Collins,02,Ji,Belitsky,Yuan,02+Collinsfragmenta.onfunc.ons

Twist-3quark-gluoncorrela9onsEfremov&Teryaev:1982&1984Qiu&Sterman:1991&1999+Twistthreefragmenta.onfunc.ons

Efremov, Teryaev; Qiu, Sterman

Q ΛQCD QT/PT <<<<QT/PT

Transverse momentum dependent

Q>>QT>=ΛQCD Q>>pT

Collinear/ twist-3

Q,QT>>ΛQCD pT~Q


Need 2 scales Q2 and pt

Remember pp: most observables one scale

Exception: DY, W/Z-production

Need only 1 scale Q2 or pt

But should be of reasonable size

should be applicable to most pp observables

AN(π0/γ/jet)



ANfromfits

day(run) : 90(43) to 90(61) / ndf 2r 8.257 / 10

Prob 0.6037p0 0.018384± -0.006277 p1 0.02641± 0.05524

q-3 -2 -1 0 1 2 3

? +

NB N

? -

NB N

-0.2

0

0.2

0.4day(run) : 90(43) to 90(61) / ndf 2r 8.257 / 10

Prob 0.6037p0 0.018384± -0.006277 p1 0.02641± 0.05524

day(run) : 90(43) to 90(61)EM-JetEnergy=55-57.5GeV

For2-photonisolatedπ0

hndf1Entries 134Mean 17.48RMS 1.848

0 5 10 15 20 25 30 35 40 45 500

10

20

30

40

50

hndf1Entries 134Mean 17.48RMS 1.848

hchi21Entries 134Mean 19.73RMS 6.42

0 5 10 15 20 25 30 35 40 45 500

2

4

6

8

10

12

hchi21Entries 134Mean 19.73RMS 6.42

Mean 1.058

RMS 0.3597

/NDF2r0 0.5 1 1.5 2 2.5

# se

ts0

10

20

30 Mean 1.058

RMS 0.3597 > 0Fx < 0Fx

Foreachsliceofdataaveragedover~18fills.Fitsarewellincontrol.

LightCone2017,MumbaiUniversity,India

² ANiscalculatedfromp0+P×ANcos(ϕ)fitsovereachfillonp0=relaAveluminosityAN=asymmetryP=polarizaAon---AN’sarecorrectedforpolarizaAonvaluesfromRHIC-fills---ANandχ2/NDFarecalculatedoverenArefills

)q(?)+Nq(BN)q(?)-Nq(BN) = q(NA

)qCos(NA× = p0 + P)q(?)+Nq(BN)q(?)-Nq(BN

20/09/2017 20

ANwithmid-rapidityacAviAes

•  Case-I:havingnocentraljet•  Case-II:havingacentraljet

20/09/2017

η=1.09,2.0η=2.6-4.2

BEMC EEMCFMS

η=-1.0,1.0

CentralEMJets forwardEMJets

towers(BEMC+EEMC):anA-kT,R=0.7,pTEM-Jet

>2.0GeV/c,-1.0<ηEM-Jet<2.0LeadingcentralEM-Jets:JetwithhighestpT


ΔΦcorrelaAonsbetweenforwardandcentralEM-Jets

20/09/2017

²  CorrelaAonisstrongerformoreN_photonJets²  ForhigherEMJetsenergy,correlaAongrowsstronger


#Eve

nts

0

50

100Entries 4163115Mean 2.16RMS 1.676

E =40-60 GeV


0

20000

40000

60000Entries 2404875Mean 2.18RMS 1.665

E = 60-80 GeV


(forward-central EMJets)q6-1 0 1 2 3 40

10000

20000


E = 80-100 GeV

#photons <=2


#Eve

nts

0

100

200 Entries 7990953Mean 2.313RMS 1.594

E = 40-60 GeV


0

100

200 Entries 6632622Mean 2.384RMS 1.55

E = 60-80 GeV


(forward-central EMJets)q6-1 0 1 2 3 40

50

100Entries 2844054Mean 2.435RMS 1.515

E = 80-100 GeV

#photons >=3

NumberofphotonsforforwardEMJets:1,23andmore

EMJetsEnergy



RHICColdQCDSchedule

STARfuturemeasurements


transverse single spin asymmetries at large …1...transverse single spin asymmetries at large...

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