119265714
Helicity operators for mesons in flight on the lattice
Motivated by the desire to construct meson-meson operators of definite relative momentum in order to study resonances in lattice QCD, we present a set of single-meson interpolating fields at non-zero momentum that respect the reduced symmetry of a cubic lattice in a finite cubic volume. These operators follow from the subduction of operators of definite helicity into irreducible representations of the appropriate little groups. We show their effectiveness in explicit computations where we find that the spectrum of states interpolated by these operators is close to diagonal in helicity, admitting a description in terms of single-meson states of identified JPC. Lastly, the variationally determined optimal superpositions of the operators for each state give rapid relaxation in Euclidean time to that state, ideal for the construction of meson-meson operators and for the evaluation of matrix elements at finite momentum.
120601853
Radiative Physics in Charmonium from Lattice QCD
Charmonium is an attractive system for the application of lattice QCD methods owing to the possibility of computing with the physical quark mass in a reasonable time. While the sub-threshold spectrum has been considered in some detail in previous works, it is only very recently that further properties such as radiative transitions and two-photon decays have come to be calculated; herein we discuss this recent progress.
125997156
Charmonium Radiative Physics
16434102
Pentaquark symmetries, selection rules and another potentially narrow state
Abstract We identify essential differences between the pentaquark and chiral soliton models of 10 5 and 8 5 pentaquarks and conventional 8 3 states, which are experimentally measurable. We show how the decays of Ξ5 states in particular can test models of the pentaquarks, recommend study of the relative branching ratios of, e.g., Ξ − 5 →Ξ − π 0 :Ξ 0 π − , and predict that the decay amplitude Ξ 5 →Ξ ∗ π is zero at leading order in pentaquark models for any mixture of 10 and the associated 8 5 . We also include a pedagogic discussion of wavefunctions in the pentaquark picture and show that pentaquark models have this 8 5 with F/D=1/3, in leading order forbidding Ξ5→ΛK. The role of Fermi–Dirac symmetry in the qqqq wavefunction and its implications for the width of pentaquarks are briefly discussed. The relative couplings g 2 (Θ Q NK Q ∗ )/g 2 (Θ Q NK Q )=3 for Q≡s,c,b. A further potentially narrow state Λ in 8 5 with JP=3/2+ is predicted around 1650 MeV.
14262604
Hybrid meson production by electromagnetic and weak interactions in a flux tube simulation of lattice QCD
We calculate rates for hybrid meson production by electromagnetic and weak interactions in the flux-tube model. Applications include photo and electroproduction at Jefferson Laboratory and HERA, and the production of light strange and charmed hybrids in the weak decays of heavy flavours. Photoproduction of some light hybrids is predicted to be prominent in charge exchange reactions, $\gamma p \to n \cal{H}$ and accessible in $\gamma p \to p \cal{H}$. Production of light or charmed hybrids in $B$ and $D$ decays may be feasible with high statistics. Photoproduction of the axial hybrid meson is predicted to be large courtesy of $\pi$ exchange, and its strange counterpart is predicted in $B \to \psi K_H(1^+)$ with $b.r. \sim 10^{-4}$. Production rates for exotic hybrid candidates $1^{-+};(0,2)^{+-}$ are given special attention. Selection rules that can help to distinguish between hybrid and conventional states with the same $J^{PC}$ are noted.
15493314
Pentaquark implications for exotic mesons
If the exotic baryon {theta}{sup +}(1540) is a correlated ududs with J{sup P}=(1{sup +}/2), then there should exist an exotic meson {theta}{sup +} with strangeness +2, J{sup P}=1{sup -}, mass {approx}1.6 GeV, decaying to K{sup +}K{sup 0} with width O(10-100) MeV. The {pi}{sub 1}(1400;1600) may be broad members of 10{+-}10 in such a picture, and it is possible that vector mesons in the 1.4-1.7 GeV mass range are related to this multiplet. We suggest that dynamical correlations may limit the spectrum of J{sup P(C)} such that the 1{sup -({+-}}{sup )} states are isolated.
119475372
QUANTUM ROTATIONAL SPECTRA AND CLASSICAL ROTORS
We consider the generalized rotor Hamiltonians capable of describing quantum systems invariant with respect to symmetry point-groups that go beyond the usual D2-symmetry of a tri-axial rotor. We discuss the canonical de-quantisation procedure to obtain the classical analogs of the original quantum Hamiltonians. Classical and quantum solutions to the Hamiltonians relevant in the nuclear physics applications are illustrated and compared using the 'usual' (D2) and an 'exotic' (Td) symmetries.
119225511
HFODD (v2.40h): User's Guide
We describe the input data and installation procedures of the code HFODD (v2.40h). The present write-up contains complete and comprehensive information that has originally been given in six independent publications. It is enhanced by the subject index and indexes of variables, input-data keywords, subroutines, and files that are used in this user guide.
18843760
Atomic Nuclei with Tetrahedral and Octahedral Symmetries
We present possible manifestations of octahedral and tetrahedral symmetries in nuclei. These symmetries are associated with the OhD and TdD double point groups. Both of them have very characteristic finger-prints in terms of the nucleonic level properties - unique in the Fermionic universe. The tetrahedral symmetry leads to the four-fold degeneracies in the nucleonic spectra; it does not preserve the parity. The octahedral symmetry leads to the four-fold degeneracies in the nucleonic spectra as well but it does preserve the parity. 
Microscopic predictions have been obtained using mean-field theory based on the relativistic equations and confirmed by using 'traditional' Schroedinger equation formalism. Calculations are performed in multidimensional deformation spaces using newly designed algorithms. 
We discuss some experimental fingerprints of the hypothetical new symmetries and possibilities of their verification through experiments.
29200135
Search for the Skyrme-Hartree-Fock Solutions for Chiral Rotation in N=75 Isotones
A search for self-consistent solutions for the chiral rotational bands in the N=75 isotones {sup 130}Cs, {sup 132}La, {sup 134}Pr, and {sup 136}Pm is performed within the Skyrme-Hartree-Fock cranking approach using SKM* and SLy4 parametrizations. The dependence of the solutions on the time-odd contributions in the energy functional is studied. From among the four isotones considered, self-consistent chiral solutions are obtained only in {sup 132}La. The microscopic calculations are compared with the {sup 132}La experimental data and with results of a classical model that contains all the mechanisms underlying the chirality of the collective rotational motion. Strong similarities between the Hartree-Fock and classical model results are found. The suggestion formulated earlier by the authors that the chiral rotation cannot exist below a certain critical frequency is further illustrated and discussed, together with the microscopic origin of a transition from planar to chiral rotation in nuclei. We also formulate the separability rule by which the tilted-axis-cranking solutions can be inferred from three independent principal-axis-cranking solutions corresponding to three different axes of rotation.
122253058
Fock-space diagonalization of the state-dependent pairing Hamiltonian with the Woods-Saxon mean field
A particle-number conserving approach is presented to solve the nuclear mean-field plus pairing Hamiltonian problem with a realistic deformed Woods-Saxon single-particle potential. The method is designed for the state-dependent monopole pairing Hamiltonian {cflx H}{sub pair}={summation}{sub {alpha}{beta}}G{sub {alpha}{beta}}c{sub {alpha}}{sup {dagger}}c{sub {bar {alpha}}}{sup {dagger}}c{sub {bar {beta}}}c{sub {beta}} with an arbitrary set of matrix elements G{sub {alpha}{beta}}. Symmetries of the Hamiltonians on the many-body level are discussed using the language of P symmetry introduced earlier in the literature and are employed to diagonalize the problem; the only essential approximation used is a many-body (Fock-space) basis cutoff. An optimal basis construction is discussed and the stability of the final result with respect to the basis cutoff is illustrated in details. Extensions of the concept of P symmetry are introduced and their consequences for an optimal many-body basis cutoff construction are exploited. An algorithm is constructed allowing to solve the pairing problems in the many-body spaces corresponding to p{approximately}40 particles on n{approximately}80 levels and for several dozens of lowest lying states with precision {approximately}(1{endash}2) {percent} within seconds of the CPU time on a CRAY computer. Among applications, the presence of the low-lying seniority s=0 solutions, that are usually poorly described in terms of the standardmore » approximations (BCS, HFB), is discussed and demonstrated to play a role in the interpretation of the spectra of rotating nuclei. {copyright} {ital 1997} {ital The American Physical Society}« less