638 research outputs found
Determining Compositeness of Hadronic Resonances: the Radiative Decay and the - Mixing
Recently the concept of compositeness has been developed so as to distinguish
whether interested hadrons are hadronic molecules or not. Here, in terms of
compositeness, we investigate molecular structure of the resonance with the radiative decay and
molecular structure of the and resonances with the
- mixing.Comment: 6 pages, 4 figures, Presentation given at the 2nd International
Symposium on Science at J-PARC (J-PARC 2014), Tsukuba, Japan, July 12-15,
201
Nuclear modification of valence-quark distributions and its effects on NuTeV sin^2 theta_W anomaly
We investigated a nuclear modification difference between up- and
down-valence quark distributions by analyzing structure function F_2 and
Drell-Yan cross-section ratios. Although nuclear modifications of the
valence-quark distributions themselves are rather well determined, it is
difficult to find their difference from the present data. We estimated such an
effect on the NuTeV sin^2 theta_W value and its uncertainty by the Hessian
method. At this stage, it is not large enough to explain the whole NuTeV
anomaly. However, the modification difference cannot be precisely determined,
so that further studies are needed.Comment: 3 pages, LaTeX, 1 eps file, to be published in Proceedings of the 6th
International Workshop on Neutrino Factories and Superbeams (NuFact04
Nuclear modification difference between u_v and d_v distributions and its relation to NuTeV sin^2 theta_W anomaly
We investigate a possible nuclear correction to the NuTeV measurement of the
weak-mixing angle sin^2 theta_W. In particular, a nuclear modification
difference between u_v and d_v distributions contributes to the NuTeV
measurement with the iron target. First, the modification differenceis
determined by a chi^2 analysis so as to reproduce nuclear data on the structure
function F_2 and Drell-Yan processes. Then, taking the NuTeV kinematics into
account, we calculate a contribution to the sin^2 theta_W determination. In
addition, its uncertainty is estimated by the Hessian method. Although the
uncertainty becomes comparable to the NuTeV deviation, the effect is not large
enough to explain the whole NuTeV sin^2 theta_W anomaly at this stage. However,
it is difficult to determine such a nuclear modification difference, so that we
need further investigations on the difference and its effect on the NuTeV
anomaly.Comment: 6 pages,3 figure
Studies of exotic hadrons by high-energy exclusive reactions
We investigate the possibility of clarifying internal structure of exotic
hadrons by high-energy exclusive reactions. In particular, the
constituent-counting rule could be used for determining the internal
configuration in large-angle exclusive scattering. As an example, we show the
cross section pi^- + p -> K^0 + Lambda(1405) in comparison with the one for the
ground-state Lambda production pi^- + p -> K^0 + Lambda. The counting rule
indicates that the cross section scales as s^8 dsigma /dt=constant if
Lambda(1405) is an ordinary three-quark baryon, whereas it is s^{10} dsigma
/dt=constant if Lambda(1405) is a five-quark baryon. Here, s and t are
Mandelstam variables. Such experiments could be possible at J-PARC, LEP, JLab,
CERN-COMPASS, and other high-energy facilities.Comment: 4 pages, 7 figures, 12th Asia Pacific Physics Conference (APPC12),
JPS Conference Proceedings in pres
Internal structure of exotic hadrons by high-energy exclusive reactions
We propose to use high-energy exclusive reactions for probing internal
structure of exotic hadron candidates. First, the constituent counting rule of
perturbative QCD can be used for finding internal configurations of an exotic
hadron candidate. It is because the number of constituents (), which
participate in the exclusive reaction, is found by the scaling behavior of the
cross section at large momentum transfer, where
is the center-of-mass energy squared. As an example, we show that the
internal structure of should be found, for example, by the
reaction . Second, the internal structure
of exotic hadron candidates should be investigated by hadron tomography with
generalized parton distributions (GPDs) and generalized distribution amplitudes
(GDAs) in exclusive reactions. Exotic nature should be reflected in the GPDs
which contain two factors, longitudinal parton distributions as indicated by
the constituent counting rule and transverse form factors as suggested by the
hadron size. The GDAs should be investigated by the two-photon process
, for example or , in
electron-positron annihilation. Since the GDAs contain information on a
time-like form factor, exotic nature should be found by studying the
invariant mass dependence of the cross section. The internal structure of
exotic hadron candidates should be clarified by the exclusive reactions at
facilities such as J-PARC and KEKB.Comment: 6 pages, LaTeX, 9 eps files, JPS Conference Proceedings of the 2nd
International Symposium on Science at J-PARC (J-PARC 2014), Tsukuba, Japan,
July 12-15, 201
A possible nuclear effect on the NuTeV sin^2 theta_W anomaly
We investigate a possible explanation for the NuTeV anomaly in terms of a
nuclear correction difference between u_v and d_v distributions. Analyzing deep
elastic scattering and Drell-Yan data for nuclear targets, we try to determine
the correction difference and its effect on the anomaly. We find that the
difference cannot be precisely determined at this stage due to the lack of data
which are sensitive to the difference. Therefore, it is difficult to draw a
solid conclusion about its effect although the anomaly could be explained, at
least partially, by this kind of nuclear correction.Comment: 3 pages, 1 figure, to be published in the proceedings of the XVIIth
Particles and Nuclei International Conference (PANIC), Santa Fe, New Mexico,
USA, October 24-28, 200
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