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.
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.
119542268
The J = 3/2 Theta* partner to the Theta(1540) baryon
If the exotic baryon $\Theta(1540)$ is $udud\bar{s}$ with $J^P = 
{1/2}^+$, we predict that there is a \10bar with $J^P = {3/2}^+$ containing a $\Theta^*(1540-1680)$. The width $\Gamma(\Theta^* \to KN)$ is at least a factor of three larger than $\Gamma(\Theta)$. The possibilities of $\Theta^* \to KN\pi$ or $\Theta \gamma$ via $M1$ and $E2$ multipoles are discussed.
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.
123115763
Excited charmonium physics from lattice QCD
Properties of excited mesons are studied using a lattice QCD simulation of a system comparable to charmonium. We extract a spectrum of states, including those with manifestly exotic quantum numbers. Radiative transition form‐factors are also computed, in particular the transition from exotic ηc1 to J/ψγ which is found to be large on the usual scale of magnetic dipole transitions.Properties of excited mesons are studied using a lattice QCD simulation of a system comparable to charmonium. We extract a spectrum of states, including those with manifestly exotic quantum numbers. Radiative transition form‐factors are also computed, in particular the transition from exotic ηc1 to J/ψγ which is found to be large on the usual scale of magnetic dipole transitions.
123280722
CHARMONIUM EXCITED STATES FROM LATTICE QCD
We apply the variational method with a large basis of interpolating operators to demonstrate the feasibility of extracting multiple excited states in charmonium from lattice QCD. The calculation is performed in the quenched approximation to QCD, using the clover fermion action on an anisotropic lattice. A crucial element of our approach is a knowledge of the continuum limit of the interpolating operators, providing important additional information on the spin assignment of the states, even at a single value of the lattice spacing. Though we find excited-state masses that are systematically high with respect to the quark potential model, and the experimental masses where known, we attribute this as most likely an artifact of the quenched approximation.
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.
16830387
Quantum rotors and their symmetries
A connection between nuclear symmetries other than those of an ellipsoidal nucleus and the properties of the implied rotational spectra are discussed. The discussion is focussed on a few examples of exotic shapes predicted recently by microscopic calculations. Some possible interpretation difficulties related to experiment are shortly mentioned.
32573284
Island of rare Earth nuclei with tetrahedral and octahedral symmetries: possible experimental evidence.
Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetrahedral Td and/or octahedral Oh symmetries sometimes at only a few hundreds of keV above the ground states in some rare earth nuclei around 156Gd and 160Yb. The underlying single-particle spectra manifest exotic fourfold rather than Kramers's twofold degeneracies. The associated shell gaps are very strong, leading to a new form of shape coexistence in many rare earth nuclei. We present possible experimental evidence of the new symmetries based on the published experimental results--although an unambiguous confirmation will require dedicated experiments.
120529658
EXOTIC DEFORMATIONS IN THE ACTINIDE REGION
Minimisation of the total nuclear energies in the 5-dimensional deformation space {α20,α22,α30,α32,α40} gives us a possibility to examine more realistically the total energy surfaces in the (β,γ) space but also in the exotic (α30,α32) projections. Basing on those results we have performed also a multi-dimensional calculations in the space of tetrahedral symmetry preserving deformations.
14367022
Nuclear Liquid Drop Model with the Surface-Curvature Terms: New Perspectives for the Hyperdeformation Studies
Nuclear liquid drop model is revisited and an explicit introduction of the surface-curvature terms is presented. The corresponding parameters of the extended classical energy formula are adjusted to the contemporarily known nuclear binding energies and ssion barrier heights. Using 2766 binding energies of nuclei with Z 8a ndN 8 it is shown that the performance of the new approach is improved by a factor of about 6, compared to the previously published liquid drop model results, in terms of both the masses (new r.m.s. deviation =0 :698 MeV) and the ssion barriers (new r.m.s. deviation of the ssion barriers of isotopes with Z> 70 is =0 :88 MeV). The role of the curvature terms and their eects on the description of the experimental quantities are discussed in detail; for comparison the parameters of the more ’traditional’ approaches are re-tted taking into account the nuclear masses known today and the performances of several variants of the model are compared. The isospin dependence in the new description of the barriers is in a good agreement with the extended Thomas-Fermi approach; it also demonstrates a good qualitative agreement with the ssion life-time systematics tested on the long chain of Fermium isotopes known experimentally. The new approach oers also a very high stability in terms of the extrapolation from the narrower range of nuclides to a more extended one - a property of particular interest for the contemporary exotic beam projects: the