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Search Results: 1 - 10 of 21039 matches for " Jen-Chieh Peng "
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Neutron Electric Dipole Moment Experiments
Jen-Chieh Peng
Physics , 2008, DOI: 10.1142/S0217732308027771
Abstract: The neutron electric dipole moment (EDM) provides unique information on CP violation and physics beyond the Standard Model. We first review the history of experimental searches for neutron electric dipole moment. The status of future neutron EDM experiments, including experiments using ultra-cold neutrons produced in superfluid helium, will then be presented.
Partonic substructure of nucleons and nuclei with dimuon production
Jen-Chieh Peng
Physics , 2010, DOI: 10.1063/1.3479363
Abstract: Dimuon production has been studied in a series of fixed-target experiments at Fermilab during the last two decades. Highlights from these experiments, together with recent results from the Fermilab E866 experiment, are presented. Future prospects for studying the parton distributions in the nucleons and nuclei using dimuon production are also discussed.
TMDs and Drell-Yan Experiments at Fermilab and J-PARC
Jen-Chieh Peng
Physics , 2008,
Abstract: The roles of the Drell-Yan experiments in studying the Transverse-Momentum-Dependent (TMD) parton distributions are discussed. Recent results from the Fermilab E866 experiment on the angular distributions of Drell-Yan dimuons in $p+p$ and $p+d$ at 800 GeV/c are presented. These data are compared with the pion-induced Drell-Yan data, and with models which attribute the $\cos 2 \phi$ azimuthal distribution to the presence of the transverse-momentum-dependent Boer-Mulders structure function $h_1^\perp$. Constraints on the magnitude of the sea-quark $h_1^\perp$ structure functions are obtained. Future prospects for studying the TMDs with Drell-Yan experiments at Fermilab and J-PARC are also discussed.
Dileptons from P-Nucleus Collisions
Jen-Chieh Peng
Physics , 1999, DOI: 10.1063/1.1301701
Abstract: Various QCD tests using recent results from fixed-target dimuon production experiments at Fermilab are discussed. We emphasize that clear evidence for scaling-violation in the Drell-Yan process remains to be established. Further experimental and theoretical work are needed to understand the polarization of the Drell-Yan pairs. The nuclear medium effects for dilepton productions are also discussed. In particular, the energy-loss of partons traversing nuclear medium is deduced from the Drell-Yan nuclear dependence.
Transverse Spin Effects in Future Drell-Yan Experiments
Jen-Chieh Peng
Physics , 2014, DOI: 10.1051/epjconf/20158501009
Abstract: We review the current status and future prospect for probing the transverse momentum dependent (TMD) parton distributions using the Drell-Yan process. We focus on the Boer-Mulders and Sivers functions, which are expected to undergo a sign-change from semi-inclusive deep-inelastic scattering (SIDIS) to Drell-Yan process. The constraints of existing Drell-Yan and SIDIS experiments on the signs of these functions are discussed. Future Drell-Yan measurements for the TMDs are also presented.
Flavor Asymmetry of the Sea Quark Distributions
Jen-Chieh Peng,Gerald T. Garvey
Physics , 1999,
Abstract: Recent deep inelastic scattering and Drell-Yan experiments have revealed a surprisingly large asymmetry between the up and down sea quark distributions in the nucleon. In this article, we review the status of the flavor asymmetry of the nucleon sea. The implications of the recent results on various theoretical models as well as possible future measurements are also discussed.
Flavor Asymmetry of Light Quarks in the Nucleon Sea
Gerald T. Garvey,Jen-Chieh Peng
Physics , 2001, DOI: 10.1016/S0146-6410(01)00155-7
Abstract: A surprisingly large asymmetry between the up and down sea quark distributions in the nucleon has been observed in recent deep inelastic scattering and Drell-Yan experiments. This result strongly suggests that the mesonic degrees of freedom play an important role in the description of the parton distributions of the hadronic sea. In this article, we review the current status of our knowledge of the flavor structure of the nucleon sea. The implications of various theoretical models as well as possible future measurements are also discussed.
Flavor Asymmetry of the Nucleon Sea and the Five-Quark Components of the Nucleons
Wen-Chen Chang,Jen-Chieh Peng
Physics , 2011, DOI: 10.1103/PhysRevLett.106.252002
Abstract: The existence of the five-quark Fock states for the intrinsic charm quark in the nucleons was suggested some time ago, but conclusive evidence is still lacking. We generalize the previous theoretical approach to the light-quark sector and study possible experimental signatures for such five-quark states. In particular, we compare the $\bar d - \bar u$ and $\bar u + \bar d - s -\bar s$ data with the calculations based on the five-quark Fock states. The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the $|uudu\bar{u}>$ and $|uudd\bar{d}>$ Fock states are also extracted.
On the extraction of the intrinsic light-quark sea in the proton
Wen-Chen Chang,Jen-Chieh Peng
Physics , 2014, DOI: 10.1103/PhysRevD.92.054020
Abstract: The HERMES collaboration recently reported a reevaluation of the strange-quark parton distribution, $S(x)$, based on kaon production in semi-inclusive deep-inelastic scattering. Two distinct results on $S(x)$ at the $x> 0.1$ region, one with a sizable magnitude and another with a vanishing content, were reported. We show that the latter result is due to a particular assumption adopted in the analysis. The impact of the new HERMES $S(x)$ result on the extraction of intrinsic light-quark sea in the proton is discussed. Given the large uncertainty in the kaon fragmentation function, we find that the latest HERMES data do not exclude the existence of a significant intrinsic strange-quark sea in the proton. The $x$ dependence of the $(s+\bar s)/(\bar u+ \bar d)$ ratio is also in qualitative agreement with the presence of intrinsic strange-quark sea.
Novel Phenomenology of Parton Distributions from the Drell-Yan Process
Jen-Chieh Peng,Jian-Wei Qiu
Physics , 2014, DOI: 10.1016/j.ppnp.2014.01.005
Abstract: The Drell-Yan massive lepton-pair production in hadronic collisions provides a unique tool complementary to the Deep-Inelastic Scattering for probing the partonic substructures in hadrons. We review key concepts, approximations, and progress for QCD factorization of the Drell-Yan process in terms of collinear or transverse momentum dependent (TMD) parton distribution functions. We present experimental results from recent fixed-target Drell-Yan as well as $W$ and $Z$ boson production at colliders, focussing on the topics of flavor structure of the nucleon sea as well as the extraction of novel Sivers and Boer-Mulders functions via single transverse spin asymmetries and azimuthal lepton angular distribution of the Drell-Yan process. Prospects for future Drell-Yan experiments are also presented.
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