unpolarized drell-yan experiments at fermilab and j-parc

Unpolarized Drell-Yan Experiments at Fermilab and J-PARC

Paul E. Reimer

7 April 2008

What do we measure with Drell-Yan?

– Selectivity for sea quarks

What Physics can we address?

– Dbar/ubar– Nuclear modifications– Large-x structure– Parton energy loss– QCD—Lam Tung Relation– Meson Structure (Seonho Choi, NP08)– Polarized Structure (Yuji Goto here, NP’08)

How and Where?Goal:

Present a

n overvi

ew of Drell-Y

an

physics

at J-P

ARC and Fermila

b

27 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

xtarget xbeam

Detector acceptance chooses xtarget and xbeam.

Fixed target ) high xF = xbeam – xtarget

Valence Beam quarks at high-x.

Sea Target quarks at low/intermediate-x.Sea Target quarks at low/intermediate-x.

Drell-Yan scattering: A laboratory for sea quarks

E906

Spect

.

Mon

te C

arlo


Advantages of 120 GeV Main Injector

The (very successful) past:

Fermilab E866/NuSeaFermilab E866/NuSea Data in 1996-1997 1H, 2H, and nucl. targets 800 GeV proton beam

Fermilab E906Fermilab E906 Data in 2009 1H, 2H, and nucl. targets 120 GeV proton Beam

Cross section scales as 1/s Backgrounds, (J/ and charm decays) scale as s

Fixed Target

Beam lines

Tevatron 800 GeVMain

Injector 120 GeV

J-PARCJ-PARC Polarized beams and

targets Meson beams 50 GeV proton Beam

The Future

Within limits


Fermilab E866 Detector Reconstruct M2, pT

, p||

M2 = x1x2s,

xF = 2p||/s1/2 ≈ x1 – x2

x1;2 =12

"

±xF +

r

xF 2+4M 2

s

#

Target-to-dump distance important– Acceptance

– Background from § decay (especially at 50 GeV)(especially at 50 GeV)

– Target/Dump Separation

– Fringe Field (polarized target)


What is the distribution of sea quarks?

In the nucleon: Sea and gluons are important:

– 98% of mass; 60% of momentum at Q2 = 2 GeV2

Not just three valence quarks and QCD. Shown by E866/NuSea d-bar/u-bar data

What are the origins of the sea? Significant part of LHC beam.

CTEQ6m

In nuclei: The nucleus is not just protons and neutrons What is the difference?

– Bound system– Virtual mesons affects antiquarks distributions


Light Antiquark Flavor Asymmetry: Brief History

Naïve Assumption:

NA51 (Drell-Yan)

E866/NuSea (Drell-Yan)

NMC (Gottfried Sum Rule)

Knowledge of distributions is data driven

– Sea quark distributions are difficult for Lattice QCD


Models Relate Antiquark Flavor Asymmetry and Spin

Meson Cloud in the nucleon—Sullivan process in DIS

¹d(x) ¡ ¹u(x) ¼¢ ¹u(x) ¡ ¢ ¹d(x)

¹dI (x) ¡ ¹uI (x) =35[¢uI (x) ¡ ¢ dI (x)]

Z 1

0

£¹d(x) ¡ ¹u(x)¤=2a¡ b3 = 0:10! a= 0:2= 2b gA =

Z 1

0[¢ u ¡ ¢ d]dx =

53¡2027

p2ab! 1:5

Z 1

0

£¹d(x) ¡ ¹u(x)¤=2a3 = 0:10 ! a = 0:14 gA =

Z 1

0[¢ u ¡ ¢ d]dx =

533a ! 1:43

hqjqi =

·1¡

3a2

¸hqjqi +

3a2hq¼jq¼i

Chiral Quark models—effective Lagrangians

L / ¹uRuL ¹dRdL + ¹uL uR ¹dL dR

Instantons

Statistical Parton Distributions

hP jP i = (1¡ a¡ b) hP0jP0i +ahN0¼jN0¼i +bh¢ 0¼j¢ 0¼i :::


Something is missing

All non-perturbative models predict large asymmetries at high x. Are there more gluons and therefore symmetric anti-quarks at higher x? Does some mechanism like instantons have an unexpected x dependence? (What is

the expected x dependence for instantons in the first place?)

Perturbative sea apparently dilutes

meson cloud effects at large-x


Extracting d-bar/-ubar From Drell-Yan Scattering

Sensitivity to d-bar/u-bar depends on kinematics

Need high xF for extraction

¾pd

2¾pp

¯¯¯¯xF >>0

¼12

·1+

¹d¹u

¸


Drell-Yan Absolute Cross Sections

¼ of data represented in plot (alternate decades, alternate targets) Last few xF bins show PDF’s “over predict” NLO cross section


Drell-Yan Absolute Cross Sections: xtarget

Reach high-x through beam proton

Large xF) large xbeam.

High-x distributions poorly understood

– Nuclear corrections are large, even for deuterium

– Lack of proton data Proton-Proton

– no nuclear corrections

– 4u(x) + d(x)

Prelim

inary

Data are free for analysis after dbar/ubar expt.

Both J-PARC and Fermilab will have similar reach in statistics and in xTarget.


Structure of nucleonic matter: How do sea quark distributions differ in a nucleus?

EMC: Parton distributions of bound and free nucleons are different.

Antishadowing not seen in Drell-Yan—Valence only effect

What can the sea parton distributions tell us about the effects of nuclear binding?

Alde et al (F

ermilab E

772) Phys. R

ev. Lett. 64 2479 (1990)

Intermediate-x seasea PDF’s absolute magnitude set by -DIS on iron.– Are nuclear effects the same for the sea as for

valence? – Are nuclear effects with the weak interaction the

same as electromagnetic?


Structure of nucleonic matter: Where are the nuclear pions?

The binding of nucleons in a nucleus is expected to be governed by the exchange of virtual “Nuclear” mesons.

No antiquark enhancement seen in Drell-Yan (Fermilab E772) data.

Contemporary models predict large effects to antiquark distributions as x increases.

Models must explain both DIS-Models must explain both DIS-EMC effect and Drell-YanEMC effect and Drell-Yan


Nuclear Antiquark Sea measured at J-PARC

J-PARC can extend reach to significantly higher x

First test QCD Factorization at low energy--must be valid. Bodwin, Brodsky and LePage PRD 39, 3287 (1989).

Study higher-twist effects

Extend reach to higher x

Pmin ¼pTA2=3

x1


Partonic Energy Loss An understanding of partonic energy loss in both

cold and hot nuclear matter is paramount to elucidating RHIC data.

Pre-interaction parton moves through cold nuclear matter and looses energy.

Apparent (reconstructed) kinematic values (x1 or xF) is shifted

Fit shift in x1 relative to deuterium

Models:

– Galvin and Milana

– Brodsky and Hoyer

– Baier et al.

X1X1


Partonic Energy Loss E866 data are consistent with E866 data are consistent with

NO partonic energy loss for all NO partonic energy loss for all three modelsthree models

Caveat: A correction must be made for shadowing because of x1—x2 correlations

– E866 used an empirical correction based on EKS fit do DIS and Drell-Yan.

E866/NuSea

Treatment of parton propagation length and shadowing are critical

– Johnson et al. find 2.7 GeV/fm (≈1.7 GeV/fm after QCD vacuum effects)

– Same data with different shadowing correction and propagation length Better data outside of shadowing region are necessary.


Parton Energy Loss

Shift in x / 1/s–Larger at 120 GeV; Even larger at Even larger at

50 GeV50 GeV Sufficient statistics to cut shadowing

region, x2 < 0.1, from data.Energy loss upper limits

based on E866 Drell-Yan

measurement

E906 uncertainties Shadowing region removed

J-PARC 50 GeV


Meson Drell-Yan(Seonho Choi, Seoul, NP08)

High-x parton distributions– High-x from of (1-x)

– Predictions for from Dyson-Schwinger, pQCD and Nambu-Jona-Lasinio models

– Data fall predictions, but poor x resolution Charge symmetry violation +/- on deuterium target

– Difficulty producing pure + beam

Kaon Parton Distributions Need 50 GeV beam for reasonable meson energy (my opinion) Low secondary beam flux

– Dump and magnet possibly not necessary (Needs simulation)

– Increase acceptance by moving spectrometer forward

J-PARC onlyJ-PARC only


Generalized Angular Distributions

Chi-Sing Lam and Wu-Ki Tung—basic formula for lepton pair production angular distributions PRD 18 2447 (1978)

Lam-Tung Relation

Direct analogy to the Callan-Gross relation in DIS

Normally written as

Unaffected by O(s) (NLO) corrections

NNLO [O(s2)] corrections also small Mirkes and

Ohnemus, PRD 51 4891 (1995)

Also holds under resummation Berger, Qiu, Rodriguez-Pedraza, PRD 76, 074006 (2007)

Robust Prediction of QCD

Helped to validate the Drell-Yan picture of quark-antiquark annihilation

for lepton pair production

d¾d

/ 1+¸ cos2µ

+¹ sin2µcosÁ

+º2sin2µcos2Á

1¡ ¸ = 2º


Lam-Tung Relation

- Drell-Yan

– Violates L-T relation

– Large (cos2) dependence

– Strong with pT

Proton Drell-Yan

– Consistent with L-T relation

– No (cos2) dependence

– No pT dependence

Alternative: Higher twist √s dependence—need J-PARC test

Boer-Mulders function h1?:

– ( W!+-X)

Valence h1?() £ valence h1

?(p)

– (pd!+-X)

Valence h1?(p) £ sea h

1?(p)

– J-PARC—both w/same Spectrometer


Transversely Polarized Target or beam

Sivers’ distribution f?1T(x, kT)

Single spin asymmetry

Possibly explanation for E704 data Collins Fragmentation function could also

produce such an asymmetry

Fe

rmila

b E

70

4,

Ph

ys.

Re

v. L

ett

. 7

7,

26

26

(1

99

6)

HERMES has observed both effects in SIDIS

With Drell-Yan: f?1T(x, kT)|DIS = - f?1T(x, kT)|D-Y

With transversely polarized target one measures sea quarks Sea quark effects might be smallSee ta

lk by Dr. Yuji G

oto

See talk by Dr. Y

uji Goto

J-PARC ONLY


Drell-Yan timeline

Fermilab PAC approved the experiment in 2001, but experiment was not scheduled due to concerns about “proton economics”

Spectrometer upgrade funded by DOE/Office of Nuclear Physics (already received $538k in FY07)

Fermilab PAC reaffirms earlier decision in Fall 2006 Scheduled to run in 2010 for 2 years of data collection

2009

2008

2011 Publications

Expt. Funded

2010Magnet Design ExperimentAnd construction Construction

Pro

po

sed

Jan

. 20

07 ExperimentRuns

J-PARC

2012

Apparatus available for future program at J-PARC

– Significant interest from collaboration for continued program here


Drell-Yan at Fermilab and J-PARC d-bar/u-bar

– Fermilab and extended range from J-PARC 50 GeV

– The origins of the sea quarks?– The high-x structure of the proton?

Antiquarks in Nuclei

Do colored partons lose energy in cold nuclear matter?

Meson Drell-Yan (J-PARC)

Polarized Drell-Yan (J-PARC)


Additional Material


FNAL E866/NuSea CollaborationAbilene Christian University

Donald Isenhower, Mike Sadler, Rusty Towell, Josh Bush, Josh Willis, Derek Wise

Argonne National LaboratoryDon Geesaman, Sheldon Kaufman,

Naomi Makins, Bryon Mueller, Paul E. Reimer

Fermi National Accelerator LaboratoryChuck Brown, Bill Cooper

Georgia State UniversityGus Petitt, Xiao-chun He, Bill Lee

Illinois Institute of TechnologyDan Kaplan

Los Alamos National LaboratoryMelynda Brooks, Tom Carey, Gerry Garvey,

Dave Lee, Mike Leitch, Pat McGaughey, Joel Moss, Brent Park, Jen-Chieh Peng, Andrea Palounek,

Walt Sondheim, Neil Thompson

Louisiana State UniversityPaul Kirk, Ying-Chao Wang, Zhi-Fu Wang

New Mexico State UniversityMike Beddo, Ting Chang, Gary Kyle,Vassilios Papavassiliou, J. Seldon,

Jason Webb

Oak Ridge National LaboratoryTerry Awes, Paul Stankus, Glenn Young

Texas A & M UniversityCarl Gagliardi, Bob Tribble, Eric Hawker,

Maxim Vasiliev

Valparaiso UniversityDon Koetke, Paul Nord


Fermilab E906/Drell-Yan CollaborationAbilene Christian University

Donald Isenhower, Mike Sadler, Rusty Towell

Academia SinicaWen-Chen Chang, Yen-Chu Chen,

Da-Shung Su

Argonne National LaboratoryJohn Arrington, Don Geesaman*,

Kawtar Hafidi, Roy Holt, Harold Jackson, David Potterveld,

Paul E. Reimer*, Patricia Solvignon

University of ColoradoEd Kinney

Fermi National Accelerator Laboratory

Chuck Brown

University of IllinoisNaomi C.R Makins,

Jen-Chieh Peng

*Co-Spokespersons

Ling-Tung UniversityTing-Hua Chang

Los Alamos National LaboratoryGerry Garvey, Mike Leitch, Pat McGaughey, Joel Moss

MarylandBetsy Beise

Rutgers UniversityRon Gilman, Charles Glashausser,

Xiaodong Jaing, Elena Kuchina, Ron Ransome, Elaine Schulte

Texas A & M UniversityCarl Gagliardi, Robert Tribble

Thomas Jefferson National Accelerator Facility

Dave Gaskell

Valparaiso UniversityDon Koetke, Jason Webb

Pending Collaborators

RIKENYuji Goto,

Atsushi Taketani, Yoshinori Fukao, Manabu Togawa

Kyoto UniversityKenIchi Imai, Tomo Nagae

Tokyo TechToshi-Aki Shibata, Yoshiyuki Miyachi

KEKShin'ya Sawada


Collaboration: Measurement of High-Mass Dimuon Production at the 50-GeV Proton Synchrotron

Brookhaven National LaboratoryM. Bai, H. Huang, A. U. Luccio, T. Roser, A.

Zelenski

University of IllinoisR. Seidl,

M. Grosse Perdekamp, J.-C. Peng

KEKS. Ishimoto, C. Ohmori, A. Molodojentsev, N.

Saito, H. Sato* , S. Sawada, J. Takano

Kyoto UniversityK. Imai

Los Alamos National LaboratoryM. Brooks, X. Jiang, G. Kunde, M. J. Leitch,

M. X. Liu, P. L. McGaughey

Osaka UniversityK. Hatanaka

RIKENY. Fukao, Y. Goto*, A. Taketani, M. Togawa

Rikkyo UniversityK. Kurita,

Tokyo TechT.-A. Shibata

Tokyo UniversityJ. Chiba

Yamagata UniversityN. Doshita, T. Iwata, K. Kondo


Collaboration: Polarized Proton Acceleration at J-PARCAbilene Christian University

L. D. Isenhower, M. Sadler, R. Towel

Argonne National LaboratoryP. E. Reimer

Duke UniversityD. Dutta, H. Gao

University of IllinoisJ.-C. Peng*

KEKS. Sawada*, K. H. Tanaka

Kyoto UniversityN. Saito

Los Alamos National LaboratoryM. J. Leitch, M. X. Liu, P. L. McGaughey

RIKENY. Goto

Tokyo TechT.-A. Shibata

Tokyo UniversityJ. Chiba

Yamagata UniversityT. Iwata, S. Kato, H. Y. Yoshida


Next-to-Leading Order Drell-Yan

Next-to-leading order diagrams complicate the picture

These diagrams are responsible for 50% of the measured cross section

Intrinsic transverse momentum of quarks (although a small effect, > 0.8)


Kulagin and Petti sea vs. valence nuclear effects

Valence Sea

Nuclear Physics A 765 (2006) 126–187


Aside: Rescaling Models in Trouble?

Prediction of mass/width modification not seen in JLab/CLAS data Nasseripour et al. (CLAS) PRL 99, 262302 (2007)


Proton Valence Structure: Unknown as x! 1Theory

• ExactSU(6): d/u!1/2• DiquarkS=0dom.: d/u!0• pQCD: d/u!3/7

Data• Binding/FermiMotioneffectsindeuterium—choiceoftreatments.

• Proton data is needed.Proton data is needed.Petratos et al.

nucl-ex/0010011

Relative Relative uncertainty up-uncertainty up-

quark distribution quark distribution (CTEQ6e)(CTEQ6e)

Reality:We don’t even know the u or d quark

distributions—there really is very little high-x proton data


Drell-Yan Absolute Cross Sections: xtarget

Measures a convolution of beam and target PDF absolute magnitude of high-x valence beam distributions absolute magnitude of the sea in the target

– Currently determined by –Fe DIS

Prelim

inary


Detector Rates

Expected single muon rates per 2£1012 protons from decay-in-flight mesons which pass through the detector ('s) and satisfy trigger matrix tracking requirements (Trks.) from liquid hydrogen and deuterium targets and the copper beam dump.

unpolarized drell-yan experiments at fermilab and j-parc

Documents

jparc meeting

hadron physics

yan physics

sea quarkswhat physics

sea target quarks

perturbative sea

distribution of sea

higher x