unpolarized drell-yan experiments at fermilab and j-parc paul e. reimer 7 april 2008 what do we...
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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
37 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
47 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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)
57 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
67 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
77 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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 :::
87 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
97 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
¸
107 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
117 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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.
127 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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?
137 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
147 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
157 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
167 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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.
177 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
187 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
197 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
207 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
217 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
227 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
237 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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)
247 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
Additional Material
257 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
267 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
277 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
287 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
297 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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)
307 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
Kulagin and Petti sea vs. valence nuclear effects
Valence Sea
Nuclear Physics A 765 (2006) 126–187
317 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
Aside: Rescaling Models in Trouble?
Prediction of mass/width modification not seen in JLab/CLAS data Nasseripour et al. (CLAS) PRL 99, 262302 (2007)
327 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
337 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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
347 April 2008 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN
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.