15584025
Polarized structure functions of nucleons and nuclei
We determine the quark distributions and structure functions for both unpolarized and polarized DIS of leptons on nucleons and nuclei. The scalar and vector mean fields in the nucleus modify the motion of the quarks inside the nucleons. By taking into account this medium modification, we are able to reproduce the experimental data on the unpolarized EMC effect, and to make predictions for the polarized EMC effect. We discuss examples of nuclei where the polarized EMC effect could be measured. We finally present an extension of our model to describe fragmentation functions.
120047394
Quark fragmentation to pions and kaons in the NJL‐jet model
We describe the quark fragmentation functions to pions and kaons in the NJL‐jet model and compare the results with empirical parametrizations. By including cascade‐like fragmentation processes, the momentum and isospin sum rules can be satisfied naturally without introducing new parameters into the theory. We associate a low energy scale with the NJL model, and perform the Q2 evolution in leading order. The results are in reasonable agreement with the empirical fragmentation functions.
18357270
Quark distributions in nucleons and nuclei
We discuss the medium modifications of quark distributions and structure functions in the framework of a chiral effective quark theory. Particular emphasis is put on the isospin dependence of the in-medium quark distributions. As an interesting application, we discuss a possible solution of the so called NuTeV anomaly. Possible extensions of the model to describe fragmentation functions are also discussed.
119264092
Spin-dependent parton distributions and structure functions
Nuclear parton distributions and structure functions are determined in an effective chiral quark theory. We also discuss an extension of our model to fragmentation functions.
120380606
A new approach to measure kaonic hydrogen X-rays
Abstract Previous kaonic hydrogen X-ray experiments suffered from a poor signal-to-background level. This has been overcome in the present measurement through the use of a gaseous hydrogen target and the imposition of a two-charged-pion tagging requirement. In this paper a full technical description is given of the experimental methods employed.
32794961
Neutrino mass constraints on beta decay.
Using the general connection between the upper limit on the neutrino mass and the upper limits on certain types of non-standard-model interactions that can generate loop corrections to the neutrino mass, we derive constraints on some non-standard-model d --> ue- nu interactions. When cast into limits on n --> pe- nu coupling constants, our results yield constraints on scalar and tensor weak interactions improved by more than an order of magnitude over the current experimental limits. When combined with the existing limits, our results yield absolute value(C(S)/C(V)) approximately < 5 x 10(-3), absolute value(C'(S)/C(V)) approximately < 5 x 10(-3), absolute value(C(T)/C(A)) approximately < 1.2 x 10(-2), and absolute value(C'(T)/C(A)) approximately < 1.2 x 10(-2).
119298313
Neutron Beta Decay: Status and Future of the Asymmetry Measurement
With more intense sources of cold and ultracold neutrons becoming available and with improved experimental techniques being developed, determination of |Vud| from neutron β decay with a similar precision to that from from superallowed β decays is within reach. Determination of |Vud| from neutron β decay, free from nuclear corrections, hold the most promise for a further improvement of the determination of |Vud|. The current and future neutron β decay correlation experiments including the UCNA experiment at Los Alamos National Laboratory are reviewed.
42563880
Parity Violating Electron Scattering on the Proton and Deuteron at Backward Angles
The parity violating asymmetry in quasielastic electron scattering from the deuteron at backward scattering angles has been recently measured for the first time. Combined with the previously performed similar measurement on the proton, this measurement provides a determination of both the proton's strange magnetic form factor G^(a)_(M) and the axial vector e-N form factor G^(a)_(A). A preliminary analysis indicates that G^(a)_(M) is slightly positive but consistent with zero and that G^(e)_(A)(T=1) is in substantial disagreement with the theoretical estimate.
287995
A multiwire proportional chamber for precision studies of neutron β decay angular correlations
Abstract A new multiwire proportional chamber (MWPC) was designed and constructed for precision studies of neutron β decay angular correlations. Its design has several novel features, including the use of low pressure neopentane as the MWPC gas and an entrance window made of thin Mylar sheet reinforced with Kevlar fibers. In the initial off-line performance tests, the gas gain of neopentane and the position resolution were studied.