Study of Exclusive Hard Processes with Hadron Beams at J-PARC. Mini Workshop on “Structure and Productions of Charmed Baryons II” August 7-9, 2014, J-PARC, Tokai. Wen-Chen Chang 章文箴 Institute of Physics, Academia Sinica 中央研究院 物理研究所. Outline.
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Study of Exclusive Hard Processes with Hadron Beams at J-PARC
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Study of Exclusive Hard Processes with Hadron Beams at J-PARC Mini Workshop on “Structure and Productions of Charmed Baryons II” August 7-9, 2014, J-PARC, Tokai Wen-Chen Chang 章文箴 Institute of Physics, Academia Sinica 中央研究院 物理研究所
Outline • Uniqueness of hadron physics studied at HiPBL of J-PARC • Selected Physics Processes: • Drell-Yan process • Hard exclusive process • Feasibility study of exclusive Drell-Yan process in P50 spectrometer • Summary
High-res., High-momentum Beam Line • High-intensity secondary Pion beam • High-resolution beam: Dp/p~0.1% Exp. Target (FF) Pion Beam Up to 20 GeV/c Collimator Dispersive Focal Point (DFP) Dp/p~0.1% 15kW Loss Target (SM) H. Noumi
High-res., High-momentum Beam Line • High-intensity secondary Pion beam • >1.0 x 107pions/sec @ 20GeV/c • High-resolution beam: Dp/p~0.1% Open a new platform for hadron physics Prod. Angle = 0deg. (Neg.) Prod. Angle = 3.1deg (Pos.) p+ p- K- K+ pbar * Sanford-Wang:15 kW Loss on Pt, Acceptance :1.5 msr%, 133.2 m H. Noumi
Uniqueness of hadron physics studied at HiPBL of J-PARC • The beam energy at J-PARC at 10-20 GeV might be most ideal for studying the hard exclusive processes and discerning the quark-hadron transition in the strong interaction. • Valance-like partonicdegrees of freedom of hadrons could be discerned, compared to the collisions at low-energy regime. • Reasonably large cross sections, compared to the collisions at higher energy.
Wigner Distribution Wigner Distribution Ji,PRL91,062001(2003) GPD d2ktdz d3r F.T. Transverse Momentum Dependent PDF Generalized Parton Distr. dx d2kt PDF Form Factors
u valence gluon (x 0.05) d sea (x 0.05) Unpolarized Parton Distributions (CTEQ6)
Origin of u(x)d(x)? • Pauli blocking of valance quarks • Meson cloud in the nucleons (Thomas 1983, Kumano 1991): Sullivan process in DIS. • Chiral quark model(Eichten et al. 1992; Wakamatsu 1992): Goldstone bosons couple to valence quarks.
Momentum Dependence of the Flavor Structure of the Nucleon SeaJ.-C. Peng, W.-C. Chang, H.-Y. Cheng, T.-J. Hou, K.-F. Liu, J.-W. Qiu, arXiv:1401.1705 • Fluctuation of a valence quark into a quark and a highly virtual gluon, • Aquick splitting of the gluon into a quark and antiquark pair • Annihilation or recombination of the quark and the newly produced antiquark into a highly virtual gluon, which is then • Absorbed by the quark.
Extracting d-bar/-ubar From Drell-Yan Scattering Ratio of Drell-Yan cross sections (in leading order—E866 data analysis confirmed in NLO) • Global NLO PDF fits which include E866 cross section ratios agree with E866 results • Fermilab E906/Drell-Yan will extend these measurements and reduce statistical uncertainty. • E906 expects systematic uncertainty to remain at approx. 1% in cross section ratio. “Flavor Structure of the Nucleon Sea” W.-C. Chang and J.-C. Peng, arXiv:1406.1260
Experimental Setup II: BoNuS RTPC 140 µm beam Helium/DME at 80/20 ratio Fit RTPC points to determine helix of proton trajectory. Momentum determined from track curvature in solenoid field. dE/dx along track in RTPC also provides momentum information. to CLAS BoNuS RTPC n Solenoid Magnet p To BoNuS RTPC M. Eric Christy Moller Catcher
Wigner Distribution Wigner Distribution Ji,PRL91,062001(2003) GPD d2ktdz d3r F.T. Transverse Momentum Dependent PDF Generalized Parton Distr. dx d2kt PDF Form Factors
number density Sivers helicity transversity Boer-Mulders Transverse momentum dependent (TMD) PDF three distribution functions are necessary to describe the quark structure of the nucleon at LO in the collinear case taking into account the quark intrinsic transverse momentum kT, At leading order 8 PDFs are needed. “TMDs” nucleon polarization T-odd Sivers function correlation between the transverse spin of the nucleon and the transverse momentum of the quark sensitive to orbital angular momentum quark polarization Boer-Mulders function correlation between the transverse spin and the transverse momentum of the quark in unpol nucleons pretzelosity
Sign Change of Sivers & Boer-Mulders FunctionsJ.C. Collins, Phys. Lett. B 536 (2002) 43A.V. Belitsky, X. Ji, F. Yuan, Nucl. Phys. B 656 (2003) 165D. Boer, P.J. Mulders, F. Pijlman, Nucl. Phys. B 667 (2003) 201Z.B. Kang, J.W. Qiu, Phys. Rev. Lett. 103 (2009) 172001 Drell-Yan SIDIS • QCD gluon gauge link (Wilson line) in the initial state (DY) vs. final state interactions (SIDIS). • Experimental confirmation of the sign change will be a crucial test of perturbative QCD and TMD physics.
number density Sivers helicity transversity Boer-Mulders Transverse momentum dependent (TMD) PDF three distribution functions are necessary to describe the quark structure of the nucleon at LO in the collinear case taking into account the quark intrinsic transverse momentum kT, At leading order 8 PDFs are needed. “TMDs” nucleon polarization T-odd Sivers function correlation between the transverse spin of the nucleon and the transverse momentum of the quark sensitive to orbital angular momentum quark polarization Boer-Mulders function correlation between the transverse spin and the transverse momentum of the quark in unpol nucleons pretzelosity
Wigner Distribution Wigner Distribution Ji,PRL91,062001(2003) GPD d2ktdz d3r F.T. Transverse Momentum Dependent PDF Generalized Parton Distr. dx d2kt PDF Form Factors
x+x x-x P P’ GPDs t Generalized Parton Distribution (GPD) Ji’s sum rule