CP Violation in τ Decays at SuperB &amp; Belle II Experiments – like Finding Signs of Dark Matter

Bigi, I. I.

doi:10.1016/j.nuclphysbps.2014.09.022

Cited by 8 publications

(13 citation statements)

References 16 publications

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“…Notice that this form of F T (s) recovers the vector-meson-dominance picture, as is generally expected[53,54] 9. Here we have used the relation g V = G V /M V , which also results from the equivalence of models I and II for the spin-1 degrees of freedom[54].…”

mentioning

confidence: 59%

“…This makes CP-violating observables particularly interesting probes of new physics (NP) beyond the SM. In this respect, the hadronic decays of the τ lepton, besides serving as a clean laboratory for testing various low-energy aspects of the strong interaction [6,7], may also allow us to explore non-standard CP-violating interactions [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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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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mentioning

confidence: 59%

Section: Introductionmentioning

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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“…One such system is the τ lepton, which is the only known lepton massive enough to decay into hadrons. In this regard, the hadronic τ decays, besides serving as a clean laboratory for studying various low-energy aspects of the strong interaction [13,14], may also allow us to explore CP -violating effects both within and beyond the SM [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

CP asymmetry in the angular distribution of τ → KSπντ decays

Chen

Yang

2020

J. High Energ. Phys.

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In this work, we study the CP asymmetry in the angular distribution of τ → K S πν τ decays, taking into account the known CP violation in K 0 −K 0 mixing. It is pointed out for the first time that, once the well-measured CP violation in the neutral kaon system is invoked, a non-zero CP asymmetry would appear in the angular observable of the decays considered, even within the Standard Model. By employing the reciprocal basis, which is most convenient when a K S(L) is involved in the final state, the CP -violating angular observable is derived to be two times the product of the time-dependent CP asymmetry in K → π + π − and the mean value of the angular distribution in τ ± → K 0 (K 0 )π ±ν τ (ν τ ) decays. Compared with the Belle results measured in four different bins of the Kπ invariant mass, our predictions lie within the margins of these measurements, except for a 1.7 σ deviation for the lowest mass bin. While being below the current Belle detection sensitivity that is of O(10 −3 ), our predictions are expected to be detectable at the Belle II experiment, where √ 70 times more sensitive results will be obtained with a 50 ab −1 data sample.

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“…We require onedimensional observables, although we also require additional data, subtle analyses, and thought. For example, one can measure the angle between two planes [41,[88][89][90], where…”

Section: -Odd Observables Wherementioning

confidence: 99%

“…We must probe regional CP asymmetries, and we must wait for Belle II (and the Super Tau-Charm Factory if & when it is completed). If polarized e + e − beams exist [88,89], that would be wonderful.…”

Section: τ Decaysmentioning

confidence: 99%

“Could charm (& τ) transitions be the ‘poor princess’ providing a deeper understanding of fundamental dynamics ?” or: “Finding novel forces”

Bigi

2015

Front. Phys.

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We know that our Universe is composed of only ∼ 4.5% "known" matter; therefore, our understanding is incomplete. This can be seen directly in the case of neutrino oscillations (without even considering potential other universes). Charm quarks have had considerable impact on our understanding of known matter, and quantum chromodynamics (QCD) is the only local quantum field theory to describe strong forces. It is possible to learn novel lessons concerning strong dynamics by measuring rates around the thresholds of [QQ] states with Q = b, c. Furthermore, these states provide us with gateways towards new dynamics (ND), where we must transition from "accuracy" to "precision" eras. Finally, we can make connections with τ transitions and, perhaps, with dark matter. Charm dynamics acts as a bridge between the worlds of light-and heavy-flavor hadrons (namely, beauty hadrons), and finding regional asymmetries in many-body final states may prove to be a "game changer". There are several different approaches to achieving these goals: for example, experiments such as the Super Tau-Charm Factory, Super Beauty Factory, and the Super Z 0 Factory act as gatekeepers -and deeper thinking regarding symmetries.

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CP Violation in τ Decays at SuperB & Belle II Experiments – like Finding Signs of Dark Matter

Cited by 8 publications

References 16 publications

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

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

CP asymmetry in the angular distribution of τ → KSπντ decays

“Could charm (& τ) transitions be the ‘poor princess’ providing a deeper understanding of fundamental dynamics ?” or: “Finding novel forces”

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