Indirect<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:math>violation and implications for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>D</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mo>−</mml:mo><mml:msup><mml:mover accent="true"><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:msup></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mm

“…The above expression for A indir CP reduces to the one commonly used [3] in the limit R f = 1 in both the decay modes, since for CP-even final states like π + π − and [6,7]. Our expression is more general and needs to be used if the possibility of direct CP violation is to be taken into account.…”

Section: Direct and Indirect Cp Asymmetriesmentioning

confidence: 99%

“…Although the approximation r f ≪ 1 is valid in the SM, it is not guaranteed to be true in the presence of NP. Higher-order terms in r f give nonuniversal contributions to A indir CP through different values for λ f [7]. The value of r f is bounded by the CP violation measurements themselves: since A dir CP (f ) ∼ O(0.01), we have |R f | ∼ 1 + O(0.01), and hence r f sin δ f sin φ f ∼ O(0.01), for both the decay modes.…”

Section: Cpmentioning

confidence: 99%

“…To compare our results with previous analyses, here we present our arguments in terms of the language and notation used in Refs. [5,6,7]. In the notation of the Particle Data Group [5], the decay amplitudes A f andĀ f [see Eq.…”

Section: Cpmentioning

confidence: 99%

“…Therefore, the assumption of exactly equal A indir CP in the π + π − and K + K − channels is, strictly speaking, not accurate. In practice, with certain "natural" expectations about the amplitudes and phases of NP contributions, the nonuniversality of A indir CP may turn out to be so small that it may be neglected [6,7], since the difference…”

Section: Introductionmentioning

confidence: 99%

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Nonuniversality of indirectCPasymmetries inD→ππ,KKdecays

2014

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We point out that, if the direct CP asymmetries in the D → π + π − and D → K + K − decays are unequal, the indirect CP asymmetries as measured in these modes are necessarily unequal. This nonuniversality of indirect CP asymmetries can be significant with the right amount of new physics contributions, a scenario that may be fine-tuned, but is still viable. A model-independent fit to the current data allows different indirect CP asymmetries in the above two decays. This could even be contributing to the apparent tension between the difference CP asymmetries ∆A CP measured through the pion-tagged and muon-tagged data samples at the LHCb. This also implies that the measurements of A Γ and y CP in the π + π − and K + K − decay modes can be different, and averaging over these two modes should be avoided. In any case, the complete analysis of CP violation measurements in the D meson sector needs to take into account the possibility of different indirect CP asymmetries in the π + π − and K + K − channels. * amol@theory.tifr.res.in † diptimoy.ghosh@roma1.infn.it ‡ bhavik@theory.tifr.res.in

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CP asymmetry in the angular distributions of τ → KSπντ decays. Part II. General effective field theory analysis

Chen

Peng

et al. 2022

J. High Energ. Phys.

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In this work, we proceed to study the CP asymmetry in the angular distributions of τ → KSπντ decays within a general effective field theory framework including four-fermion operators up to dimension-six. It is found that, besides the commonly considered scalar-vector interference, the tensor-scalar interference can also produce a non-zero CP asymmetry in the angular distributions, in the presence of complex couplings. Using the dispersive representations of the Kπ form factors as inputs, and taking into account the detector efficiencies of the Belle measurement, we firstly update our previous SM predictions for the CP asymmetries in the same four Kπ invariant-mass bins as set by the Belle collaboration. Bounds on the effective couplings of the non-standard scalar and tensor interactions are then obtained under the combined constraints from the CP asymmetries measured in the four bins and the branching ratio of τ−→ KSπ−ντ decay, with the numerical results given respectively by $$ \operatorname{Im}\left[{\hat{\upepsilon}}_S\right] $$ Im ϵ ̂ S = −0.008 ± 0.027 and $$ \operatorname{Im}\left[{\hat{\upepsilon}}_T\right] $$ Im ϵ ̂ T = 0.03 ± 0.12, at the renormalization scale μτ = 2 GeV in the $$ \overline{\mathrm{MS}} $$ MS ¯ scheme. Using the best-fit values, we also find that the distributions of the CP asymmetries can deviate significantly from the SM expectation in almost the whole Kπ invariant-mass region. Nevertheless, the current bounds on $$ \operatorname{Im}\left[{\hat{\upepsilon}}_S\right] $$ Im ϵ ̂ S and $$ \operatorname{Im}\left[{\hat{\upepsilon}}_T\right] $$ Im ϵ ̂ T are still plagued by large experimental uncertainties, but will be improved with more precise measurements from the Belle II experiment as well as the proposed Tera-Z and STCF facilities. Assuming further that the non-standard scalar and tensor interactions originate from a weakly-coupled heavy new physics well above the electroweak scale, the SU(2)L invariance of the resulting SMEFT Lagrangian would indicate that very strong limits on $$ \operatorname{Im}\left[{\hat{\upepsilon}}_S\right] $$ Im ϵ ̂ S and $$ \operatorname{Im}\left[{\hat{\upepsilon}}_T\right] $$ Im ϵ ̂ T could also be obtained from the neutron electric dipole moment and the $$ {D}^0-{\overline{D}}^0 $$ D 0 − D ¯ 0 mixing. With the bounds from these processes taken into account, it is then found that, unless there exist extraordinary cancellations between the new physics contributions, neither the scalar nor the tensor interaction can produce any significant effects on the CP asymmetries (relative to the SM predictions) in the processes considered, especially under the “single coefficient dominance” assumption.

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IndirectCPviolation and implications forD0−D¯0and

Cited by 92 publications

References 23 publications

The UTfit collaboration average of D meson mixing data: spring 2012

The UTfit collaboration average of D meson mixing data: spring 2012

Nonuniversality of indirectCPasymmetries inD→ππ,KKdecays

CP asymmetry in the angular distributions of τ → KSπντ decays. Part II. General effective field theory analysis

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