We study perturbative amplitudes in a large class of theories obtained by marginal deformations of the N = 4 supersymmetric Yang-Mills. We find that planar amplitudes in the deformed theories are closely related to planar amplitudes in the original N = 4 SYM. For some classes of deformations the amplitudes essentially coincide with the N = 4 amplitudes to all orders in planar perturbation theory. For more general classes of marginal deformations, the equivalence holds at up to four loops, and at five loops it is likely to break down. This implies that the iterative structure of planar MHV amplitudes recently discovered by Bern, Dixon and Smirnov in [1] for the N = 4 theory also manifests itself in a wider class of theories.

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возраста, у 4%-в периоде менопаузального перехода, у 21%-в поздней стадии менопаузального перехода и у 47%-через 3 года после наступления менопаузы [1]. В значительном количестве наблюдений сухость, зуд, жжение вульвы и влагалища являются следствием атрофических и/или дистрофических процессов. По определению Международного общества исследователей заболеваний вульвы, дистрофия вульвы-это нарушение роста и созревания эпителия, что приводит к появлению белых пятен. Атрофия вульвы-атрофия эластических волокон [2], почти полное их отсутствие и/или дегенерация. Кроме того, отмечается умеренная околососудистая инфиль

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Within a real space renormalisation group (RG) scheme, we study the criticality of the ferromagnetic Z(4) model on an anisotropic square lattice. We use an RG cluster which has already proved to be very efficient for the Potts model on the same lattice. The establishment of the RG recurrence relations is greatly simplified through the break-collapse method. The phase diagram (exhibiting ferromagnetic, paramagnetic and nematic-like phases) recovers all the available exact results, and is believed to be of high precision everywhere. If the model is alternatively thought of as being associated with a particular hierarchical lattice rather than with the square lattice, then it is exact everywhere.