In this work, we perform a detailed study of the $τ^-\toπ^-π^0γν$ decay process within the resonance chiral theory. We pay special attention to the triple-product asymmetry in the $τ^-\toπ^-π^0γν$ process. The minimal resonance chiral Lagrangian and the odd-intrinsic parity resonance operators are simultaneously included to calculate the decay amplitudes. Various invariant-mass distributions in the $π^-π^0$, $π^-γ$ and $π^0γ$ systems are studied and they reveal different resonance dynamics. We further predict the intriguing nonzero triple-product asymmetry distributions, which may provide useful guidelines for future experimental measurements conducted at the Belle-II and super tau-charm facilities.
Gauge invariance and finite width effects in radiative two-pion tau lepton decay
rho^{ \pm }矢量介子对τ-> pi pi nu γ衰变的贡献被认为是确定这种轻矢量介子磁偶极矩的一个潜在来源。为了保持整个衰变振幅的规范不变性，我们采用了一种类似于荷电规范玻色子费米子环方案的方法来考虑ρ ^{ \pm }矢量介子的有限宽度效应.对ρ ^{ \pm }介子和W^{\pm }规范玻色子的传播子和电磁顶点的单圈修正的吸收部分在圈中无质量粒子的极限下具有相同的形式，表明这是自旋为1的不稳定粒子的普遍特征。模型依赖的贡献τ-> π π nu γ衰变被抑制固定的两π不变的质量分布在ρ介子质量值。由此产生的光子能量和角分布是相对敏感的ρ磁偶极矩的影响。
The role of the a_1(1420) resonance in the three-pion decays of the tau lepton is investigated using a phenomenological model. For all data before 2008, roughly equal fit quality is achieved when the basic a_1(1260) resonance is supplemented with either a_1(1640) or a_1(1420). However, two recent and more precise data sets require resonances with masses that are not very far from that of a_1(1420). This suggests that the axial-vector resonance that accompanies the a_1(1260) in the three-pion decays of the tauon is a_1(1420), not a_1(1640), as believed up to now. More data are needed to demonst…
我们研究了Delta S=0衰变tau -> omega pi nu_tau和tau -> a_1 pi nu_tau以及Delta S=1衰变tau -> K pi pi nu_tau中的CP破坏。我们假设新的物理是带电的希格斯粒子。我们发现，相当大的CP违反的影响是可能的，在tau -> a_1 π nu_tau（偏振相关的速率不对称性）和tau -> omega π nu_ tau（三重产品不对称性）。Δ S=1衰减τ-> K pi pi nu_tau可以通过几个共振进行。我们构建了两个修改后的速率不对称性和三重产品不对称性，这种衰变，并讨论这些不对称性的潜在敏感性。
Phenomenology in the Higgs Triplet Model with the A_4 Symmetry
本文讨论了在最简单的A_4对称Higgs三重态模型中双荷和单荷希格斯玻色子玻色子（SU（2）_L-三重态场）的唯象。这些希格斯玻色子的质量本征态是明确地从希格斯势得到的。结果表明，它们衰变成一对轻子具有独特的味道结构，可以在大型强子对撞机测试，如果他们的一些质量低于TeV规模。可以自然地获得τ到bar（mu）e e e和τ到bar（e）mu mu的相当大的衰减率，而在该模型中几乎禁止其他τ到l l'l“”、mu到bar（e）e e e和l到l' gamma。这些希格斯玻色子玻色子的贡献中微子的非标准相互作用也被认为是。
We consider exclusive multi-peripheral production of four charged pions in proton-proton collisions at high energies with simultaneous exchange of three pomerons/reggeons. The amplitude(s) for the genuine $2 \to 6$ process are written in the Regge approach. The calculation is performed with the help of the GenEx Monte Carlo code. Some corrections at low invariant masses in the two-body subsystems are necessary for application of the Regge formalism. We estimate the corresponding cross section and present differential distributions in rapidity, transverse momenta and two- and four-pion invarian…
Lepton Mass Effects in Single Pion Production by Neutrinos
我们重新考虑应用于重子共振的中微子激发的费曼-基斯林格-拉夫达尔模型。轻子质量的影响包括在内，使用的形式主义的Kuzmin，柳金和Naumov。此外，我们考虑了介子极对强子轴向矢流的贡献。应用这种新的形式主义的反应nu（mu）+ p --> mu + Delta在E（nu）约1 GeV的小角度给出了一个抑制的截面，在阿德勒的前向散射定理的屏蔽校正。在E（nu）约7 GeV处应用于过程nu（tau）+ p -> tau + Delta导致预测向前运动的轻子的右手tau极化，与基于等压线模型的计算一致。我们的形式主义是一个改进版本的Rein-Sehgal模型，将轻子质量效应与PCAC一致的方式。
Recently, the RHICf Collaboration measured the transverse single-spin asymmetries of the very forward neutral pion in polarized $p+p$ collisions at $\sqrt{s}=510$ GeV, produced at large pseudorapidity ($η\gtrsim 6$). The data show large asymmetries both in longitudinal momentum fraction $x_F$ and transverse momentum $p_T$ at $p_T<1\,\mathrm{GeV}/c$. Employing baryonic triple Regge exchanges, we describe the complete RHICf data for the first time and show that the neutral pion production at low $p_T$ can be interpreted as a diffractive one.
We present an overview of searches fo violation of lepton flavor universality with focus on low energy precision probes using pions, kaons, tau leptons, and nuclear beta decays. The current experimental results are reviewed, the theoretical status within the context of the Standard Model is summarized, and future prospects (both experimental and theoretical) are discussed. We review the implications of these measurements for physics beyond the Standard Model by performing a global model-independent fit to modified $W$ couplings to leptons and four-fermion operators. We also discuss new physics…
Hadronic tau decays belong to the processes that show a resonance-like structure in the axial vector current in the $1-2$ GeV range. This structure, often denoted as the $a_1$ meson, seems to show different properties in different processes. The process $τ\rightarrow 3πν_τ$ allows for a clean separation of weak and strong effects and a clear production mechanism. We examine how this structure can be related to interactions between the three pions that emerge in the final state. In particular we start from the interactions between all two body combinations.
我们考虑了τ->K pi pi nu_tau中的CP破坏效应，假设带电的希格斯玻色子提供了一个新的振幅，可以干扰通常的标准模型振幅。我们考虑四个CP奇观测量--常规速率不对称性、两个修改的速率不对称性和三重积不对称性。规则的速率不对称性预计是小的，因为它需要新的物理振幅与包含强子标量形状因子的标准模型振幅的干涉。其他CP不对称性可能在其新的物理范围方面更有前途。数值估计表明，修改后的三重产品的不对称性的最大可获得的值是百分之一的顺序。
Bose-Einstein correlations of pairs of identical charged pions produced in hadronic Z decays and in 7 TeV pp minimum bias interactions are investigated within the framework of the tau-model.
In this work, we study the lepton number violating tau decays via two intermediate on-shell Majorana neutrinos $N_j$ into two charged pions, and a charged lepton $τ^{\pm} \to π^{\pm} N_j \to π^{\pm} π^{\pm} \ell^{\mp}$. We consider the scenario where the heavy neutrino masses are within $0.5$ GeV $\leq M_N \leq 1.5$ GeV. We evaluated the possibility to measure the modulation of the decay width along the detector length for these processes at taus factories, such as Belle II. We study some realistic conditions which could lead to the observation of this phenomenon at futures $τ$'s factories.
我们考虑了τ-> 3 pi nu_ tau和4 pi nu_ tau（Δ S = 0）以及τ-> K pi pi nu_tau（Δ S = 1）中的CP破坏效应，假设这些过程的通常标准模型振幅干扰了带电希格斯玻色子介导的类似振幅。在Delta S = 0的情况下，我们特别关注中间共振过程tau -> V pi nu_tau（V=omega，rho和a_1），并考虑三个CP-奇数观测值-部分速率不对称性，偏振相关不对称性和三重产物不对称性。在Delta S = 1的情况下，我们研究部分利率不对称，两个“修改”利率不对称，和三重产品不对称。预计Delta S = 0和Delta S = 1情况下的部分速率不对称性较小。对其他不对称性的评估表明，它们可能是可以测量的。
