119278846
Holonomies of gauge fields in twistor space 4: Functional MHV rules and one-loop amplitudes
Abstract We consider generalization of the Cachazo–Svrcek–Witten (CSW) rules to one-loop amplitudes of N = 4 super Yang–Mills theory in a recently developed holonomy formalism in twistor space. We first reconsider off-shell continuation of the Lorentz-invariant Nair measure for the incorporation of loop integrals. We then formulate an S-matrix functional for general amplitudes such that it implements the CSW rules at quantum level. For one-loop MHV amplitudes, the S-matrix functional correctly reproduces the analytic expressions obtained in the Brandhuber–Spence–Travaglini (BST) method. Motivated by this result, we propose a novel regularization scheme by use of an iterated-integral representation of polylogarithms and obtain a set of new analytic expressions for one-loop NMHV and N 2 MHV amplitudes in a conjectural form. We also briefly sketch how the extension to one-loop non-MHV amplitudes in general can be carried out.
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.
17985110
Holonomies of gauge fields in twistor space 2: Hecke algebra, diffeomorphism, and graviton amplitudes
Abstract We define a theory of gravity by constructing a gravitational holonomy operator in twistor space. The theory is a gauge theory whose Chan–Paton factor is given by a trace over elements of Poincare algebra and Iwahori–Hecke algebra. This corresponds to a fact that, in a spinor-momenta formalism, gravitational theories are invariant under spacetime translations and diffeomorphism. The former symmetry is embedded in tangent spaces of frame fields while the latter is realized by a braid trace. We make a detailed analysis on the gravitational Chan–Paton factor and show that an S-matrix functional for graviton amplitudes can be expressed in terms of a supersymmetric version of the holonomy operator. This formulation will shed a new light on studies of quantum gravity and cosmology in four dimensions.
18483460
Multigluon amplitudes , N = 4 constraints and the WZW model
Classical N = 4 Yang-Mills theory is defined by the superspace constraints. We obtain a solution of a subset of these constraints and show that it leads to the maximally helicity violating (MHV) amplitudes. The action which leads to the solvable part of the constraints is a Wess-Zumino-Witten (WZW) action on a suitably extended superspace. The non-MHV tree amplitudes can also be expressed in terms of this action.
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.
37143222
PARTICLE EMISSION BUT ALSO FISSION IN THE DECAY OF VERY EXCITED NUCLEI
An extension of the s tat is t ica l model for the study of very excited nuclei is presented. The temperature and angular momentum dependences of the fission barriers are obtained in a l iqu id drop picture. I t provides us with the relevant potential landscapes for some col lect ive variables which evolve during the decay according to a generalized transport equation. The l i gh t part ic le evaporation during the fast f ission process and the f ission after compound nucleus formation is calculated and compared with some available experimental results, e.g. for '•"Ar + U at 27 MeV/u. The competing process of part ic le emission (cooling) during the thermal equilibrium prevents a complete transfer of excitation energy along the whole evolution of the system. Such nuclei should be called warm instead of hot.
119374559
Predictions of the residue cross-sections for the elements Z = 113 and Z = 114
Abstract.A good reproduction of experimental excitation functions is obtained for the 1n reactions producing the elements with Z = 108, 110, 111 and 112 by the combined usage of the two-step model for fusion and the statistical decay code KEWPIE. Furthermore, the model provides reliable predictions of productions of the elements with Z = 113 and Z = 114 which will be a useful guide for plannings of experiments.
18150688
Theory of Nuclear Reactions Leading to Superheavy Elements
Dynamical reaction theory is presented for synthesis of superheavy elements. Characteristic features of formation and surviving are discussed, which combinedly determine final residue cross sections of superheavy elements. Preliminary results on Z=114 are also given.
365149
On Theoretical Problems in Synthesis of Superheavy Elements
Towards precise predictions of residue cross sections of the superheavy elements, recent theoretical developments of reaction mechanisms are presented, together with the remaining problems which give rise to ambiguities in absolute values of cross sections predicted.
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