Effective-field theory analysis of the τ − → η(′)π−ντ decays

Garcés, E. A.; Villanueva, M. Hernández; Castro, G. López; Roig, Pablo

doi:10.1007/jhep12(2017)027

Cited by 40 publications

(113 citation statements)

References 76 publications

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“…As recently pointed out in Ref. [12], a third exclusive channel that can provide useful information is τ → ηπν τ , 2 Recently Ref. [27] found a ee µ = 503.74 ± 1.96 using similar data but a different averaging method than Ref.…”

Section: Exclusive Decaysmentioning

confidence: 89%

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Hadronic τ Decays as New Physics Probes in the LHC Era

et al. 2019

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We analyze the sensitivity of hadronic τ decays to non-standard interactions within the modelindependent framework of the Standard Model Effective Field Theory (SMEFT). Both exclusive and inclusive decays are studied, using the latest lattice data and QCD dispersion relations. We show that there are enough theoretically clean channels to disentangle all the effective couplings contributing to these decays, with the τ → ππντ channel representing an unexpected powerful New Physics probe. We find that the ratios of non-standard couplings to the Fermi constant are bound at the sub-percent level. These bounds are complementary to the ones from electroweak precision observables and pp → τ ντ measurements at the LHC. The combination of τ decay and LHC data puts tighter constraints on lepton universality violation in the gauge boson-lepton vertex corrections.

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Section: Exclusive Decaysmentioning

confidence: 89%

“…Refs. [11,12]), with the exception once again of the simple τ → πν τ , Kν τ channels. The goal of this letter is to amend this situation presenting an unprecedented comprehensive analysis of the NP reach of CP -conserving hadronic tau decays.…”

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confidence: 99%

Hadronic τ Decays as New Physics Probes in the LHC Era

et al. 2019

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“…For the tensor form factor, however, there exists no experimental data that can guide us to construct it, and we have to rely on theory. While a q 2 -independent tensor form factor or its normalization [45] can be derived from the leading-order chiral perturbation theory (χPT) [46][47][48][49] with tensor sources [50,51], we have to get its q 2 dependence by solving numerically the dispersion relation [25,52], with its phase obtained in the context of chiral theory with resonances (RχT) [53,54]. It should be mentioned that the tensor form factors given in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…µναβ σ αβ has been used to further get the relation P µναβL = P µναβ R † .Taking the functional derivative of Eq. (4.3) with respect to the tensor sourcet µν , with all the other external sources put to zero, expanding u(φ a ) in powers of φ a , and then taking the suitable hadronic matrix element, one can finally get[25,45,52] …”

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confidence: 99%

CP asymmetry in τ→KSπντ decays within the standard model and beyond

Chen

Yang

et al. 2019

Phys. Rev. D

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This work aims to explore the 2.8σ discrepancy observed between the BaBar measurement and the Standard Model prediction of the CP asymmetry in τ → K S πν τ decays. Firstly, we reproduce the known CP asymmetry due to K 0 −K 0 mixing by means of the reciprocal basis, which is convenient when a K S(L) is involved in the final state. As the Kπ tensor form factor plays a crucial role in generating an extra direct CP asymmetry that can arise only from the interference of vector and tensor operators, we then present a dispersive representation of this form factor, with its phase obtained in the context of chiral theory with resonances, which fulfills the requirements of unitarity and analyticity. Finally, the τ → K S πν τ decays are analyzed both within a model-independent low-energy effective theory framework and in a scalar leptoquark scenario. It is observed that the CP anomaly can be accommodated in the model-independent framework, even at the 1σ level, together with the constraint from the branching ratio of this decay; it can be, however, marginally reconciled only at the 2σ level, due to the specific relation between the scalar and tensor operators in the scalar leptoquark scenario.

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“…From 1 ab −1 , Belle II will have the capacity to test SM predictions for the τ → ηπν decay. Furthermore, given the suppression expected in the SM, new physics searches are achievable [25]. Figure 7: Prospects for 90% C.L.…”

Section: Searches For Second Class Currents In τ Decaysmentioning

confidence: 99%

Prospects for $\tau$ lepton physics at Belle II

Villanueva

2019

SciPost Phys. Proc.

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The Belle II experiment is an upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric e + e − collider. The accelerator has already successfully completed the first phase of commissioning and first electron positron-collisions in Belle II were observed in April 2018. The design luminosity of SuperKEKB is 8x10 35 cm −2 s −1 and the Belle II experiment aims to record 50 ab −1 of data. Belle II has a broad program of τ physics, in particular, precision measurements of Standard Model parameters and searches of lepton flavor and lepton number violations, benefiting from the large cross-section of the pairwise τ lepton production in e + e − collisions. In this talk, we will review the τ lepton physics program of Belle II.

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Effective-field theory analysis of the τ − → η(′)π−ντ decays

Cited by 40 publications

References 76 publications

Hadronic τ Decays as New Physics Probes in the LHC Era

Hadronic τ Decays as New Physics Probes in the LHC Era

CP asymmetry in τ→KSπντ decays within the standard model and beyond

Prospects for $\tau$ lepton physics at Belle II

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