标题： tau 介子衰变为五个介子在 TAUOLA 中 显示英文标题

标题： tau Decays to Five Mesons in TAUOLA

摘要： tau衰变库TAUOLA在过去十年中变得越来越流行。 然而，随着数据精度的不断提高，其中一些功能已经变得不足。 一个要求是实现进入五个介子加中微子的衰变，并具有现实的衰变振幅。 本说明描述了向这一方向迈出的一步。 对于2pi- pi+ 2pi0模式，引入了三个衰变链tau- --> a_1- nu --> rho- (--> pi- pi0) omega (--> pi- pi+ pi0) nu，tau- --> a_1- nu --> a_1- (--> 2pi- pi+) f_0 (--> 2pi0) nu，以及tau- --> a_1- nu --> a_1- (--> pi- 2pi0) f_0 (--> pi + pi-) nu，这些衰变链基于对各种共振耦合和传播子的简单假设。 对于pi- 4pi0和3pi- 2pi+模式，采用了类似的振幅（不包括rho omega贡献）。 因此，五π介子振幅基于一个简单的模型，但可以被认为是一个初步的现实示例。 相空间生成包括在单一通道中预先采样omega和a_1共振的可能性。 这可能目前对于物理应用和测试来说已经足够。 通过比较蒙特卡罗和解析结果对生成器的新部分进行了技术测试。 为此，使用了一个非现实但易于计算的纯标量振幅，用于进入五个无质量π介子的衰变。 显示英文摘要

摘要： The tau-decay library TAUOLA has gained popularity over the last decade. However, with the continuously increasing precision of the data, some of its functionality has become insufficient. One of the requirements is the implementation of decays into five mesons plus a neutrino with a realistic decay amplitude. This note describes a step into this direction. For the 2pi- pi+ 2pi0 mode the three decay chains tau- --> a_1- nu --> rho- (--> pi- pi0) omega (--> pi- pi+ pi0) nu, tau- --> a_1- nu --> a_1- (--> 2pi- pi+) f_0 (--> 2pi0) nu, and tau- --> a_1- nu --> a_1- (--> pi- 2pi0) f_0 (--> pi + pi-) nu are introduced with simple assumptions about the couplings and propagators of the various resonances. Similar amplitudes (without the rho omega contributions) are adopted for the pi- 4pi0 and 3pi- 2pi+ modes. The five-pion amplitude is thus based on a simple model, which, however, can be considered as a first realistic example. Phase-space generation includes the possibility of presampling the omega and a_1 resonances, in one channel only, however. This is probably sufficient for the time being, both for physics applications and for tests. The technical test of the new part of the generator is performed by comparing Monte Carlo and analytical results. To this end a non-realistic, but easy to calculate, purely scalar amplitude for the decay into five massless pions was used.