15089471
Gauge invariant electromagnetic two-point function for heavy-light quark systems.
A gauge invariant electromagnetic two-point function, crucial to the investigations of the violation of isospin symmetry, is derived for heavy-light quark systems. Thus QED can be consistently introduced into the QCD sum rule method, which was not previously possible.
16718501
The Kaon-Photoproduction Of Nucleons In The Chiral Quark Model
In this paper, we develop a general framework to study the mesonphotoproductions of nucleons in the chiral quark model. The S and U channel resonance contributions are expressed in terms of the ChewGoldberger-Low-Nambu (CGLN) amplitudes. The kaon-photoproduction processes, γp → K+Λ, γp → K+Σ0, and γp → K0Σ+, are calculated. The initial results show that the quark model provides a much improved description of the reaction mechanism for the kaon-photoproductions of the nucleon with less parameters than the traditional phenomenological approaches. PACS numbers: 13.75.Gx, 13.40.Hq, 13.60.Le,12.40.Aa
119334067
Longitudinal transitions of baryon resonances in the constituent quark model
A longitudinal transition operator that satisfies the gauge invariance requirement is introduced in the constituent quark model. The corresponding longitudinal transitions from the ground state of the nucleon to resonances of the baryon are calculated. The study shows that the longitudinal coupling plays an important role in the understanding of the structure of the baryon.
33315431
Spin structure of nucleons in a quark model with constituent gluons.
120492049
Octupole degree of freedom for nuclei near 152Sm in a reflection-asymmetric relativistic mean-field approach
The potential energy surfaces of even-even isotopes near 152Sm are investigated within the constrained reflection-asymmetric relativistic mean-field approach using parameter sets PK1 and NL3. It is shown that the critical-point candidate nucleus 152Sm marks the shape/phase transition not only from U(5) to SU(3) symmetry, but also from the octupole deformed ground state in 150Sm to the quadrupole deformed ground state in 154Sm. The important role of the octupole deformation driving pair (?2f7/2, ?1i13/2) is demonstrated based on the components of the single-particle levels near the Fermi surface. In addition, the patterns of both the proton and the neutron octupole deformation driving pairs (?2f7/2, ?1i13/2) and (?2d5/2, ?1h11/2) are investigated.
101147336
Impedance Computation of Main Components in CSNS/RCS
38207022
Complete screening of a magnetic flux string by vacuum polarization in 3+1 dimensions.
The feedback effects of the vacuum current induced by a magnetic flux string in 3 + 1 dimensions are studied. It is found that the induced magnetic field cancels the applied one completely; i.e., a magnetic flux string does not exist in 3 + 1 dimensions.
42674415
PQCD analysis of inclusive semileptonic decays of B mesons.
We develop the perturbative QCD formalism for inclusive semileptonic {ital B} meson decays, which includes Sudakov suppression from the resummation of large radiative corrections near the high end of charged lepton energy. Transverse degrees of freedom of partons are introduced to facilitate the factorization of {ital B} meson decays. Ambiguities appearing in the quark-level analysis are then avoided. A universal distribution function, arising from the nonperturbative Fermi motion of the {ital b} quark, is constructed according to the heavy quark effective field theory based operator product expansion, through which the mean and the width of the distribution function are related to hadronic matrix elements of local operators. Charged lepton spectra of the {ital B}{r_arrow}{ital X}{sub {ital ul}}{nu} decay are presented. We find 50{percent} suppression near the end point of the spectrum. The overall suppression on the total decay rate is 8{percent} for the free quark model, and is less than 7{percent} for the use of smooth distribution functions. With our predictions, it is then possible to extract the Cabibbo-Kobayashi-Maskawa matrix element {parallel}{ital V}{sub {ital ub}}{parallel} from experimental data. We also discuss possible implications of our analysis when confronted with the rather small observed semileptonic branching ratio in {ital B} mesonmore » decays. {copyright} {ital 1996 The American Physical Society.}« less
31943448
Extracting Energy from a Black Hole through Its Disk.
When some magnetic field lines connect a Kerr black hole with a disk rotating around it, energy and angular momentum are transferred between them. If the black hole rotates faster than the disk, ca&solm0;GMH>0.36 for a thin Keplerian disk, then energy and angular momentum are extracted from the black hole and transferred to the disk (MH is the mass and aMH is the angular momentum of the black hole). This way, the energy originating in the black hole may be radiated away by the disk. The total amount of energy that can be extracted from the black hole spun down from ca&solm0;GMH=0.998 to ca&solm0;GMH=0.36 by a thin Keplerian disk is approximately 0.15MHc2. This is larger than approximately 0.09MHc2, which can be extracted by the Blandford-Znajek mechanism.
2293560
Kaon photoproduction on the neutron using deuterium.
The three processes \ensuremath{\gamma}+d\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Lambda}}}^{0}$(${\mathrm{\ensuremath{\Sigma}}}^{0}$)+${\mathit{K}}^{0}$+p and \ensuremath{\gamma}+d\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Sigma}}}^{\mathrm{\ensuremath{-}}}$+${\mathit{K}}^{+}$+p are investigated in the framework of the impulse approximation. The exclusive reactions d(\ensuremath{\gamma},Kp)Y where the proton is detected in coincidence with the ${\mathit{K}}^{0}$ or ${\mathit{K}}^{+}$ should provide unique signatures for each of the processes. In most kinematic situations the final-state Yp interaction is insignificant and the elementary process cross section for \ensuremath{\gamma}+n\ensuremath{\rightarrow}Y+K can be reliably extracted. Cross-section estimates are given for several models of the basic production operator.
17940028
Perturbative QCD analysis of B meson decays.
The resummation of large QCD radiative corrections, including leading and next-to-leading logarithms, in the pion electromagnetic form factor is reviewed. A similar formalism is applied to exclusive processes involving heavy mesons, and leads to Sudakov suppression for the semileptonic decay {ital B}{r_arrow}{pi}{ital l}{nu}. It is found that, with the inclusion of Sudakov effects, a perturbative QCD analysis of this decay is reliable for the energy fraction of the pion above 0.4. Combining predictions from soft pion theorems we estimate that the upper limit of the matrix element {parallel}{ital V}{sub {ital ub}}{parallel} is 2.8{endash}4.8{times}10{sup {minus}3} from different models of the {ital B} meson wave function. {copyright} {ital 1996 The American Physical Society.}