Charmed Hadron Production in Polarized pp Collisions

To extract information about polarized gluons in the proton, production of charmed hadrons, in particular, \Lambda_c^+ baryon in pp collisions was studied. We calculated the transverse momentum distribution and the pseudo-rapidity distribution of the spin correlation asymmetry A_{LL} between the initial proton and the produced \Lambda_c^+. Those statistical sensitivities were also calculated under the condition of RHIC experiment. We found that the pseudo-rapidity distribution of A_{LL} is promising for testing the model of polarized gluons in the proton and also the spin-dependent fragmentation model of a charm quark decaying into \Lambda_c^+ baryon.Comment: 1+6 pages, Latex2e, 4 eps figures, Talk given at SPIN 2002, Brookhaven National Laboratory, September 9-13, 2002, To appear in the Proceeding

Probing Polarized Gluon Distributions through Charmed Hadron Production in Polarized pp Collisions at BNL--RHIC Energy

In order to extract information about behavior of polarized gluons in the nucleon, charmed hadron productions, i.e. D* meson and Lambda_c baryon productions, are studied in polarized pp reactions at BNL-RHIC energy. For these processes, the spin correlation asymmetry D_{LL} between the target proton and the produced charmed hadron, and its statistical sensitivity delta D_{LL} are calculated. From analyses on these processes, we found that the pseudo-rapidity distribution of D_{LL} in the limited transverse momentum region is quite effective for distinguishing the model of polarized gluons as well as the model of spin-dependent fragmentation functions.Comment: 1+14 pages, 14 figures, added references and comments, To appear in Int. Journal of Modern Phys.

Spectroscopy and Decays of Heavy Mesons

Assuming Coulomb-like as well as confining scalar potential, we have solved Shr\"odinger equation perturbatively in $1/m_Q$ with a heavy quark mass $m_Q$. The lowest order equation is examined carefully. Mass levels are fitted with experimental data for $D/B$ mesons at each level of perturbation. Meson wave functions obtained thereby can be used to calculate ordinary form factors as well as Isgur-Wise functions for semileptonic weak decays and other physical quantities. All the above calculations are expanded in $1/m_Q$ order by order to determine parameters as well as to compare with results of Heavy Quark Effective Theory.Comment: 4 page

Is the Z^+(4430) a radially excited state of D_s?

We present the interpretation that the recently discovered Z^+(4430) by the Belle Collaboration can be a radial excitation of the cs-bar state. We give an explicit cs-bar candidate for this state by calculating the mass value in our semirelativistic quark potential model and also give a natural interpretation on the reason why the decay mode Z-> J/\psi \pi^+ has not yet been seen while Z-> \psi' \pi can be seen.Comment: 6 pages, 4 figure

Mixing angle between 3P1^3P_1 and 1P1^1P_1 in HQET

Some claim that there are two independent mixing angles ($\theta = 35.3^\circ$, $-54.7^\circ$) between $^3P_1$ and $^1P_1$ states of heavy-light mesons in heavy quark symmetric limit, and others claim there is only one ($\theta = 35.3^\circ$). We clarify the difference between these two and suggest which should be adopted. General arguments on the mixing angle between $^3L_L$ and $^1L_L$ of heavy-light mesons are given in HQET and a general relation is derived in heavy quark mass limit as well as that including the first order correction in $1/m_Q$.Comment: 6 pages, 1 tabl

Lambda_c^+ production in polarized pp scattering and polarized gluon distribution

To extract information about the polarized gluon distribution, \dg, in the nucleons, we propose Lambda_c^+ productions in polarized pp scattering, p + \vec{p} \to \vec{Lambda_c^+} + X, which will be observed at RHIC experiment starting soon. For this process, we have calculated the spin correlation differential cross section, d\Delta \sigma/d\pt, and the spin correlation asymmetry defined by \A_ll \equiv [ d \Delta \sigma / d \pt ] / [ d \sigma / d\pt ]. We have found that the \A_ll is sensitive to the polarized gluon distribution in the nucleon and thus the process is promising for testing \Delta G(x,Q^2).Comment: 10 pages, LaTex2e, 6 figures.(V2: typos fixed. Conclusions unchanged

Probing nucleon strangeness in phi electroproduction

We investigate $\phi$ meson electroproduction to probe the hidden strangeness content of the nucleon. We found that even a small amount of the $s\bar{s}$ admixture in the nucleon wavefunction can lead to a significant change in several double polarization asymmetries in $\phi$ electroproduction, which can be tested experimentally at current electron facilities.Comment: 3 pages, 1 figure (2 eps files), LaTeX2e with espcrc1.sty, Talk at the XVI International Conference on Few-Body Problems in Physics (FB16), Taipei, Taiwan, March 6-10, 200