17399206
Production and decay of the neutral top pion in high-energy e+ e- colliders
We study the production and decay of the neutral top-pion � 0 predicted by topcolor-assisted technicolor(TC2) theory. Our results show that, except the dominant decay modes b ¯, ¯ and gg, the � 0 t can also decay into and Z modes. It can be significantly produced at high energy e + e collider(LC) experiments via the processes e + e → � 0 and e + e → Z� 0 t. We further calculate the production cross sections of the processes e + e → � 0 → ¯ and e + e → Z� 0 → Z¯ tc. We find that the signatures of the neutral top-pion � 0 can be detected via these processes.
119223958
Suggestion for measuring the weak dipole moment of τ lepton at Z factory
Three new observables for Z-factory to measure the weak dipole moment of $\tau$ lepton ($d_w^\tau$) are proposed. As those observables employed at LEP-I, the new observables depend on the real and imaginary parts of $d_w^\tau$ linearly, thus we calculate the slopes, i.e. the linear coefficients of the dependence, precisely and find that the obtained slopes are much lager than those employed at LEP-I. It means that the signal for the weak dipole moment $d_w^\tau$ may be enhanced quite a lot, if one employs the new observables. Being superior to those at LEP-I, we recommend measuring the weak dipole moment $d_w^\tau$ in terms of the new observables if re-analyzing the data of LEP-I or doing the measurement at a possible Z-factory in the near future.
119448015
Probing gluon helicity distribution and quark transversity through hyperon polarization in singly polarized pp collisions
We study the polarization of hyperon in different processes in singly polarized $pp$ collisions, in particular its relation to the polarized parton distributions. We show that by measuring hyperon polarization in particularly chosen processes, one can extract useful information on these parton distributions. We show in particular that, by measuring the $\Sigma^+$ polarization in high $p_T$ direct photon production process, one can extract information on the gluon helicity distribution; and by measuring the transverse polarization of hyeprons with high $p_T$ in singly polarized reactions, one can obtain useful information on the transversity distribution. We present the numerical results obtained for those hyperon polarizations using different models for parton distribution function and those for the spin transfer in fragmentation processes.
15963183
Hyperon polarization in e^-p -->e^-HK with polarized electron beams
We apply the picture proposed in a recent Letter for transverse hyperon polarization in unpolarized hadron-hadron collisions to the exclusive process e − e − nπ + with longitudinally polarized electron beams. We present the predictions for the longitudinal polarizations of the hyperons or neutron in these reactions, which can be used as further tests of the picture.