Ground-state energies are investigated in a many-quark model with pairing interactions, which has the su(4)-algebraic structure. Exact eigenstates in the boson realization method are constructed by imposing a color-singlet condition developed in the previous paper. An interaction term breaking the su(4)-dynamical symmetry plays an important role to determine the ground state. As a result, a quark-pairing state or a quark-triplet state as a nucleon is realized with a certain value of a variable which is regarded as an order parameter. In addition to the parameter regions in which these ground states are realized, it is shown that there are two transition regions between the quark-pairing and the quark-triplet states with different values of the order parameter.
We present a new computation in a field-theoretical model of Coulomb gauge QCD of the first radial and angular excitations of a qqq system in a SU(3) flavor singlet state, Lambda_S. The traditional motivation for the study is that the absence of flavor singlets in the lowest-lying spectrum is a direct consequence of the color degree of freedom. (The calculation is tested with decuplet baryons Delta(1232) and Omega(1672).) We also analyze decay branching fractions of the flavor singlet baryon for various masses with the simplest effective Lagrangians.
We apply the basis light front quantization (BLFQ) approach to describe the valence structures of the charged light meson ground states. Specifically, the light front wavefunctions of $π^\pm$, $ρ^\pm$, $K^\pm$, and $K^{*\pm}$ are obtained as the eigenvectors of the light front effective Hamiltonians with confinement potentials supplemented by the color singlet Nambu--Jona-Lasinio (NJL) interactions. We adjust our model such that the spectrum of these ground states and the charge radii of the pseudoscalar states agree with experimental results. We present the elastic form factors and parton dis…
The precise mechanism for production of quarkonium at hadron colliders is still an open question. Within non-relativistic quantum chromodynamics, quarkonium production cross sections can be factorized into short-distance, perturbative contributions and universal, non-perturbative, long-distance matrix elements, and then summed over quantum numbers of the heavy quark pair. In principle, at short-distances, the heavy quark pair can be either in a color-singlet or color-octet state, and it is desirable to establish the relative contributions to compare with data and to make predictions in differe…
We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate ho…
J/ΨProduction in pp Collisions at \sqrt s = 200 GeV at RHIC
我们利用基于pQCD和NRQCD的色单重态和色八重态机制，在PHENIX探测器的接收范围内，研究了RHIC中pp碰撞中的J/O2产生。在\sqrt s = 200 GeV时，色八重态机制再现了pp碰撞中J/π产生的RHIC数据，包括p_T分布、快度分布和总截面.与八重态贡献相比，颜色单重态机制导致对总截面的贡献相对较小。
We study Landau gauge gluon propagators in two-color QCD at finite quark chemical potential ($μ_q$) and temperature ($T$). We include medium polarization effects at one-loop by quarks into massive gluon propagators, and compared the analytic results with the available lattice data. We particularly focus on the high density phase of color-singlet diquark condensates whose critical temperature is $\sim 100$ MeV with weak dependence on $μ_q$. At zero temperature the color singlet condensates protect the IR limit of electric and magnetic gluon propagators from the medium screening effects. At fini…
