353 research outputs found
Charmonium-nucleon interactions from the time-dependent HAL QCD method
The charmonium-nucleon effective central interactions have been computed by
the time-dependent HAL QCD method. This gives an updated result of a previous
study based on the time-independent method, which is now known to be
problematic because of the difficulty in achieving the ground-state saturation.
We discuss that the result is consistent with the heavy quark symmetry. No
bound state is observed from the analysis of the scattering phase shift;
however, this shall lead to a future search of the hidden-charm pentaquarks by
considering channel-coupling effects.Comment: 8 pages, 8 figure
Lattice QCD Study of the Nucleon-Charmonium Interaction
The -nucleon interaction is studied by lattice QCD calculations. At
the leading order of the derivative expansion, the interaction consists of four
terms: the central, the spin-spin, and two types of tensor forces. We determine
these spin-dependent forces quantitatively by using the time-dependent HAL QCD
method. We find that the spin-spin force is the main cause of the hyperfine
splitting between the and the states, while the two tensor
forces have much smaller effects on the S-wave scattering processes.Comment: 5 pages, 4 figure
Huge electron-hole exchange interaction in aluminum nitride
Optical spectroscopy is performed for c-plane homoepitaxial aluminum nitride (AlN) films. The temperature dependence of the polarization-resolved photoluminescence spectra reveals the exciton fine structure. The experimental results demonstrate that the electron-hole exchange interaction energy (j) in AlN is j=6.8 meV, which is the largest value for typical III-V and II-VI compound semiconductors. We propose the effective interatomic distance as the criterion of the electron-hole exchange interaction energy, revealing a universal rule. This study should encourage potential applications of excitonic optoelectronic devices in nitride semiconductors similar to those using II-VI compound semiconductors
Baryon-Baryon Interactions in the Flavor SU(3) Limit from Full QCD Simulations on the Lattice
We investigate baryon-baryon (BB) interactions in the 3-flavor full QCD
simulations with degenerate quark masses for all flavors. The BB potentials in
the orbital S-wave are extracted from the Nambu-Bethe-Salpeter wave functions
measured on the lattice. We observe strong flavor-spin dependences of the BB
potentials at short distances. In particular, a strong repulsive core exists in
the flavor-octet and spin-singlet channel (the 8_s representation), while an
attractive core appears in the flavor singlet channel (the 1 representation).
We discuss a relation of such flavor-spin dependence with the Pauli exclusion
principle in the quark level. Possible existence of an H-dibaryon resonance
above the Lambda-Lambda threshold is also discussed.Comment: 16 pages, 4 figures, ptptex.cls use
Hadron-Hadron Interactions from Imaginary-time Nambu-Bethe-Salpeter Wave Function on the Lattice
Imaginary-time Nambu-Bethe-Salpeter (NBS) wave function is introduced to
extend our previous approach for hadron-hadron interactions on the lattice.
Scattering states of hadrons with different energies encoded in the NBS
wave-function are utilized to extract non-local hadron-hadron potential. "The
ground state saturation", which is commonly used in lattice QCD but is hard to
be achieved for multi-baryons, is not required. We demonstrate that the present
method works efficiently for the nucleon-nucleon interaction (the potential and
the phase shift) in the 1S_0 channel.Comment: 13 pages, 6 figure
Quantification of Emotions for Facial Expression: Generation of Emotional Feature Space Using Self-Mapping
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