Dec. 1, 2005 S. Sawada / J-PARC-HS05 1 Dimuon measurement at J-PARC (LoI-15: Physics of high-mass dimuon production at the 50-GeV Proton Sy nchrotron) Shin’ya Sawada (KEK) Collaboration Abilene Christian University Argonne National Laboratory Duke University High Energy Accelerator Research Organization (KEK) University of Illinois at Urbana-Champaign Kyoto University Los Alamos National Laboratory Massachusetts Institute of Technology Tokyo Institute of Technology
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Shin’ya Sawada (KEK) Collaboration Abilene Christian University Argonne National Laboratory
Dimuon measurement at J-PARC (LoI-15: Physics of high-mass dimuon production at the 50-GeV Proton Synchrotron). Shin’ya Sawada (KEK) Collaboration Abilene Christian University Argonne National Laboratory Duke University High Energy Accelerator Research Organization (KEK) - PowerPoint PPT Presentation
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Dec. 1, 2005 S. Sawada / J-PARC-HS05 1
Dimuon measurement at J-PARC(LoI-15: Physics of high-mass dimuon production at the 50-GeV Proton Synchrotron)
Shin’ya Sawada (KEK)
CollaborationAbilene Christian UniversityArgonne National Laboratory
Duke UniversityHigh Energy Accelerator Research Organization (KEK)
University of Illinois at Urbana-ChampaignKyoto University
Los Alamos National LaboratoryMassachusetts Institute of Technology
Tokyo Institute of Technology
Dec. 1, 2005 S. Sawada / J-PARC-HS05 2
Contents
Physics Goals– Flavor asymmetry (d-bar/u-bar) at large xBj
– Antiquark distribution in nuclei– Quark energy loss in nuclei
– d-bar/u-bar via J/ production
– Drell-Yan and J/ with polarized target/polarized beam Dimuon Spectrometer High Momentum Beamline To do (toward proposal submission)
– Firm collaboration!– Real work including MC simulation of the detectors etc.– Physics with polarized beams?
Dec. 1, 2005 S. Sawada / J-PARC-HS05 3
Dimuon Spectrum from Fermilab Experiments
A series of experiments: E605/772/789/866– 800 GeV/c p + p/d/A +-X
Two components in the +- spectrum.– Continuum: Drell-Yan process– Vector mesons: J/,
• Closed geometry
•Vertical bending
Dec. 1, 2005 S. Sawada / J-PARC-HS05 4
d-bar/u-bar Asymmetry Measurement
Ratio of p+d cross section to p+p d-bar/u-bar
Drell-Yan:
J/Psi, Upsilon (800 GeV):
pd
2 ppx1 x2
1
21
d (x)
u (x)
)(
)(1
2
1
221
xg
xg
p
n
xx
pp
pd
Dec. 1, 2005 S. Sawada / J-PARC-HS05 5
dbar/ubar at Large x using 50 GeV Protons
DY cross section is ~16 times larger at 50 GeV than at 800 GeV.
2121
, fixedat 1
xxsdxdx
d DY
J-PARC can measure d-bar/u-bar at larger x.
Dec. 1, 2005 S. Sawada / J-PARC-HS05 6
d-bar/u-bar Asymmetry and the Origins of the Nucleon Sea
d-bar/u-bar asymmetry suggests that there are two origins of the antiquarks in the nucleon, one from the perturbative g q qbar and the other from the meson cloud.
d-bar/u-bar measurement probes parton structure at peripheral regions of the nucleon.
From ACU web.
Dec. 1, 2005 S. Sawada / J-PARC-HS05 7
Modification of Parton Distributions in Nuclei
EMC effect observed in DIS
How is the antiquark distribution modified in nuclei?
(p+A)/(p+d)
Sensitive to u-bar distribution in nuclei.
Dec. 1, 2005 S. Sawada / J-PARC-HS05 8
Quark Bremsstrahlung in Nuclear Medium
Landau-Pomeranchuk-Migdal (LPM) effect of medium modification for electron brems has been observed at SLAC