123157220
A Molecular Model for High-Spin Heavy-Ion Resonances
A new molecular model is presented in detail, in which collective motions of the di-nuclear system are described in the rotating molecular frame. The model is applied to high-spin resonances observed in 24 Mg + 24 Mg scattering. A stable configuration of the system is found to be a pole-pole one, due to the prolate shape of the 24 Mg nuclei. Normal modes at the equilibrium are solved to give rise to various molecular levels, which appear to be in good correspondence with the experiment
31758429
Resonances due to the Landau-Zener transition.
We have derived a new useful analytic formula for the {ital T} matrix in the quantum-mechanical perturbation approach within the two-state problem with finite-range coupling which is appropriate for the discussion of the Landau-Zener transition. The resonancelike behaviors were predicted by classical or semiclassical approach in which constant coupling between two adiabatic states was assumed. In the quantum-mechanical approach, inclusion of the effect of reasonable finite-range coupling would not destroy the pattern of the resonancelike structures so much, while the magnitude of the calculated cross section is merely about 10% of that calculated by the semiclassical approach.
121736993
On Fission Dynamics
14579423
Theory of fusion hindrance and synthesis of the superheavy elements
Abstract The two-step model for fusion reactions of massive systems is briefly reminded. By the use of fusion probabilities obtained by the model and of survival probabilities obtained by the new statistical code, we predict xn residue cross sections for 48 Ca+actinide systems leading to superheavy elements with Z=114, 116 and 118.
28272098
Diffusion over a saddle with a langevin equation
The diffusion problem over a saddle is studied using a multidimensional Langevin equation. An analytical solution is derived for a quadratic potential and the probability to pass over the barrier deduced. A very simple solution is given for the one-dimensional problem and a general scheme is shown for higher dimensions.
120154304
Evidence for nuclear Landau-Zener effect: New resonance mechanism in heavy-ion reactions
Characteristic resonancelike peaks recently observed in the angle-integrated inelastic cross sections for the /sup 13/C-/sup 17/O system are understood in terms of the Landau-Zener excitation mechanism at energy level crossings. Angle-integrated inelastic cross sections estimated with the Landau-Zener formula show a series of resonancelike peaks as a function of incident energy, each of which is associated with a grazing angular momentum of the relative motion between nuclei. Simple expressions are given for resonance energies and ''widths'' of new ''resonances.'' This resonance mechanism is a new one, which has not been known in nuclear reactions nor in atomic collisions, although it is based on the well-known Landau-Zener promotion mechanism.
14986084
Holonomies of gauge fields in twistor space 1: Bialgebra, supersymmetry, and gluon amplitudes
Abstract We introduce a notion of holonomy in twistor space and construct a holonomy operator by use of a spinor-momenta formalism in twistor space. The holonomy operator gives a monodromy representation of the Knizhnik–Zamolodchikov (KZ) equation, which is mathematically equivalent to a linear representation of a braid group. We show that an S-matrix functional for gluon amplitudes can be expressed in terms of a supersymmetric version of the holonomy operator. A variety of mathematical and physical concepts, such as integrability, general covariance, Lorentz invariance and Yangian symmetry, are knit together by the holonomy operator. These results shed a new light on gauge theories in four-dimensional spacetime.
119406982
Emergence of longitudinal 7-branes and fuzzy S 4 in compactification scenarios of M(atrix) theory
In M(atrix) theory, there exist membranes and longitudinal 5-branes (L5-branes) as extended objects. Transverse components of these brane solutions are known to be described by fuzzy ${\mathbf{C}\mathbf{P}}^{k}$ ($k=1$, 2), where $k=1$ and $k=2$ correspond to spherical membranes and L5-branes of ${\mathbf{C}\mathbf{P}}^{2}\ifmmode\times\else\texttimes\fi{}{S}^{1}$ world-volume geometry, respectively. In addition to these solutions, we here show the existence of L7-branes of ${\mathbf{C}\mathbf{P}}^{3}\ifmmode\times\else\texttimes\fi{}{S}^{1}$ geometry, introducing extra potentials to the M(atrix) theory Lagrangian. As in the cases of $k=1$, 2, the L7-branes (corresponding to $k=3$) also break the supersymmetries of M(atrix) theory. The extra potentials are introduced such that the energy of a static L7-brane solution becomes finite in the large $N$ limit where $N$ represents the matrix dimension of fuzzy ${\mathbf{C}\mathbf{P}}^{3}$. As a consequence, fluctuations from the L7-branes are suppressed, which effectively describes compactification of M(atrix) theory down to 7 dimensions. We show that one of the extra potentials can be considered as a matrix-valued 7-form. The presence of the 7-form in turn supports a possibility of Freund-Rubin type compactification. This suggests that our modification of M(atrix) theory can also lead to a physically interesting matrix model in four dimensions. In hope of such a possibility, we further consider compactification of M(atrix) theory down to fuzzy ${S}^{4}$ which can be defined in terms of fuzzy ${\mathbf{C}\mathbf{P}}^{3}$. Along the way, we also find a new L5-brane solution to M(atrix) theory which has purely spherical geometry in the transverse directions.
44215083
Fuzzy S(4) and its construction
We present construction of fuzzy S, utilizing the fact that CP is an S bundle over S. Fuzzy S is obtained by imposing an additional algebraic constraint on fuzzy CP. Hence, as in the case of fuzzy CP = SU(4)/U(3), fuzzy S is globally defined on R with the additional constraint on top of the construction of fuzzy CP. We consider the commutative limit of fuzzy S and find that it naturally gives commutative S in terms of homogeneous coordinates on CP. We also discuss exact matrix-function correspondence of fuzzy S. In conclusion, it is proposed that fuzzy S is described by a certain form of block-diagonal matrix whose embedding square matrix represents fuzzy CP.
14286968
An interpretation of multigraviton amplitudes
Abstract We obtain alternative expressions for the multigraviton tree level amplitudes and discuss their general properties. In particular, by analogy with Yang–Mills theory, we find that some combinatoric structure can be carried by a Chan–Paton factor of general relativity as a gauge theory.
16024304
Noncommutative gravity: Fuzzy sphere and others
Gravity on noncommutative analogues of compact spaces can give a finite mode truncation of ordinary commutative gravity. We obtain the actions for gravity on the noncommutative two-sphere and on the noncommutative ${\mathbf{CP}}^{2}$ in terms of finite dimensional $(N\ifmmode\times\else\texttimes\fi{}N)$ matrices. The commutative large N limit is also discussed.