$A_{\textrm{CP}}[D_{(s)}^{0,+} \to V \gamma]$ from Large ${\cal O}_8$

James Lyon; Roman Zwicky

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$A_{\textrm{CP}}[D_{(s)}^{0,+} \to V \gamma]$ from Large ${\cal O}_8$

James Lyon, Roman Zwicky

High Energy Physics - Phenomenology · Submitted 24 Oct 2012

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim We show that the interference of the long-distance (LD) terms with the ${\cal O}_8$ matrix element can give rise to $A_{\text{CP}}^{D \to V \gamma} = \textrm{few} \cdot 10^{-3}$ (for reference values ${\textrm{Im}}[C_8^{NP}] \approx 10^{-3}$).

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CP-violation in $\Delta A_{\textrm {CP}} = -0.154(29)$, in the $D^0 \to \pi^+\pi^-/K^+K^-$ system, is established and its central value is one order of magnitude above the naive Standard Model (SM) estimate. It remains unclear whether this is due to currently incalculable strong interaction matrix elements or genuine new physics (NP) such as a shift in ${\cal O}_8$ with a weak phase. We show that the interference of the long-distance (LD) terms with the ${\cal O}_8$ matrix element can give rise to $A_{\text{CP}}^{D \to V \gamma} = \textrm{few} \cdot 10^{-3}$ (for reference values ${\textrm{Im}}[C_8^{NP}] \approx 10^{-3}$). In addition, it is pointed out that the ratio of left- to right-handed (photon polarisation) LD amplitudes is measurable in time-dependent CP (TDCP) asymmetries. We argue that both theory and experimental consideration favour weak annihilation (WA) as the dominant LD contribution. More definite progress could be achieved by either computing the radiative corrections to WA or the measurement of the charged modes $D^+_{(d,s)} \to (\rho,K^{*})^+ \gamma$ and $D_s \to \rho^+ \gamma$.

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What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	CP-violation in $\Delta A_{\textrm {CP}} = -0.154(29)$, in the $D^0 \to \pi^+\pi^-/K^+K^-$ system, is established and its central value is one order of magnitude above the naive Standard Model (SM) estimate.	background 0.95	0.13	0.16	asserted 1.00
s1	It remains unclear whether this is due to currently incalculable strong interaction matrix elements or genuine new physics (NP) such as a shift in ${\cal O}_8$ with a weak phase.	gap 0.78	0.07	0.05	hedged possibility 0.47
s2	We show that the interference of the long-distance (LD) terms with the ${\cal O}_8$ matrix element can give rise to $A_{\text{CP}}^{D \to V \gamma} = \textrm{few} \cdot 10^{-3}$ (for reference values ${\textrm{Im}}[C_8^{NP}] \approx 10^{-3}$).	result 0.95	0.87	0.52	asserted 0.56
s3	In addition, it is pointed out that the ratio of left- to right-handed (photon polarisation) LD amplitudes is measurable in time-dependent CP (TDCP) asymmetries.	contribution 0.45	0.46	0.05	asserted 0.65
s4	We argue that both theory and experimental consideration favour weak annihilation (WA) as the dominant LD contribution.	interpretation 0.88	0.69	0.19	hedged possibility 0.72
s5	More definite progress could be achieved by either computing the radiative corrections to WA or the measurement of the charged modes $D^+_{(d,s)} \to (\rho,K^{*})^+ \gamma$ and $D_s \to \rho^+ \gamma$.	future work 1.00	0.15	0.08	hedged possibility 1.00

What kind of paper the classifier reports this is: theoretical result 0.94 · evidence from argument 0.77.

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The paper

Original abstract

CP-violation in $\Delta A_{\textrm {CP}} = -0.154(29)$, in the $D^0 \to \pi^+\pi^-/K^+K^-$ system, is established and its central value is one order of magnitude above the naive Standard Model (SM) estimate. It remains unclear whether this is due to currently incalculable strong interaction matrix elements or genuine new physics (NP) such as a shift in ${\cal O}_8$ with a weak phase. We show that the interference of the long-distance (LD) terms with the ${\cal O}_8$ matrix element can give rise to $A_{\text{CP}}^{D \to V \gamma} = \textrm{few} \cdot 10^{-3}$ (for reference values ${\textrm{Im}}[C_8^{NP}] \approx 10^{-3}$). In addition, it is pointed out that the ratio of left- to right-handed (photon polarisation) LD amplitudes is measurable in time-dependent CP (TDCP) asymmetries. We argue that both theory and experimental consideration favour weak annihilation (WA) as the dominant LD contribution. More definite progress could be achieved by either computing the radiative corrections to WA or the measurement of the charged modes $D^+_{(d,s)} \to (\rho,K^{*})^+ \gamma$ and $D_s \to \rho^+ \gamma$.

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Cited by 3 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Radiative three-body D-meson decays in and beyond the standard model
hep-ph 2020-09 conditional novelty 6.0 of 10

Radiative three-body charm decays D→Kπγ, D→ππγ and D→KKγ have predicted branching ratios of order 10^-3 to 10^-5 and provide new observables to identify QCD mechanisms and probe new physics.
Isospin asymmetries in $B\to (K^*,\rho) \gamma/ l^+ l^-$ and $B \to K l^+ l^-$ in and beyond the Standard Model
hep-ph 2013-05 conditional novelty 6.0 of 10

Standard Model isospin asymmetries in B to K, K*, rho plus lepton pairs are computed to be below 1.5 percent at low dilepton mass, and a ratio of the rho-gamma and K*-gamma asymmetries is proposed as a quasi-null test...
Exclusive Chromomagnetism in heavy-to-light FCNCs
hep-ph 2012-12 accept novelty 6.0 of 10

Light-cone sum rules give the first estimate of O8 matrix elements in B/D to light meson plus photon transitions, at a few percent of the leading penguin form factors but with a large CP-even phase.

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27 arXiv papers cite this in 45 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 35 sentences without a confident label

Contests it 2 papers

We also, in general, disagree with the conclusion in [ref] that the “only” place the models with a warped extra dimension can show their effect are in CP asymmetries in $D→X_uγ$ besides $ΔA_CP$[For detailed studies of the connection between these two observables cf. [ref] .].

Manifestations of Warped Extra Dimension in Rare Charm Decays and Asymmetries · Summary · contest 0.73
We showed that the LCSR computations at next-to-leading order of Refs. [ref] fail to reproduce our results for the form factors of the $D_s$ meson, and that a pure VMD parametrization does not always reproduce their momentum behavior.

Lattice calculation of the $D_{s}$ meson radiative form factors over the full kinematical range · Conclusions · contest 0.95

Builds on it 1 paper

In this work we study time-dependence in $D →V γ$ decays, where $V$ denotes a vector meson, following a proposal for $B_s$-mesons [ref] [We thank Jolanta Brodzicka for bringing this to our attention.], and briefly discussed in [ref] for charm.

The photon polarization in radiative $D$ decays, phenomenologically · Introduction · 0.94

Uses its data or values 2 papers

CP violation in charm is also constrained by data on $ΔA_CP=A_CP(K^+K^-)-A_CP(π^+π^-) ∼-2Im[C_8-C_8']sinδ_KK-ππ$ [ref] , where $ΔA_CP=-0.00134±0.00070$ [ref] .

Rare radiative charm decays within the standard model and beyond · Model-independently · 0.90
The authors of Ref. [ref] have also provided the values of the radiative form factors $F_A$ and $F_V$ for the $D_s$ meson at a single kinematic point $x_γ=0.846$; $F_A(x_γ=0.846)=-0.44$ and $F_V(x_γ=0.846)=-0.11$.

Lattice calculation of the $D_{s}$ meson radiative form factors over the full kinematical range · Phenomenological parameterization of the form factors · 0.90

Compares with it 1 paper

The obtained result in this analysis agrees with theoretical calculations based on light-cone sum rules [ref] , hybrid framework [ref] and vector-meson dominance [ref] .

Search for the radiative decay $D^+_s \to \gamma \rho(770)^+$ · Summary · 0.97

Cites it as support 1 paper

Model calculations carried out in [ref] appear to bear out this situation.

Searching for the Origin of CP violation in Cabibbo Suppressed D-meson Decays · Candidates for Enhanced CP violation for Penguin-Like New Physics · 1.00

Cites it as background 2 papers

Nevertheless, there have been a number of phenomenological studies on the new-physics (NP) sensitivities of rare charm decays, including radiative and rare semileptonic $D$-meson decays induced by $c →uγ$ and $c →u ℓ^+ℓ^-$ transitions, see e.g. [ref] .

$D \to \rho \,\ell^+\ell^-$ Decays in the QCD Factorization Approach · Introduction · 0.97
There are also QCD sum rules calculation done by authors of Ref. [ref] and more recent one in Ref. [ref] .

Theoretical perspective on rare and radiative charm decays · Exclusive decay modes: $D →V γ$ · 0.95

What it cites · 33 sentences without a confident label

Builds on 3 papers

Partly building up on ideas in [ref] we have shown how $Im[C_8^(')]$ become observable in CP-asymmetries in $D →V γ$.

Shedding light on CP violation in the charm system via D to V gamma decays · Conclusions · 0.96
Slightly extending the notation in [ref] one gets, [equation] where $δ$ is the unknown strong phase difference between the $KK$ and $ππ$ states which is expected to be sizeable.

Direct CP violation in charm and flavor mixing beyond the SM · $A_CP$ in $D^0 →ππ/KK$ · 0.84
The latter might be measured, in analogy to $B_s →ϕγ$ case [ref] , in the rates $D^0 →(ρ^0,ω) γ$ and the one for $D̅^0$ without flavour-tagging, which has experimental advantages, though it has to be added that the relatively small width difference in the $D^0$ system, $y_D/y_B_s ≃0.1$, means that roughly a hundred times more data has to be accumulated to achieve the same precision on $H$ in the $D^0$- as in the $B_s$-system.

Exploiting the width difference in B_s -> phi gamma · Time-dependent CP-violation · 0.81

Uses the method or tool of 1 paper

To get an idea of the size of the NP contribution [ref] one might resort to naive factorisation (NF) e.g. [ref] .

Direct CP violation in charm and flavor mixing beyond the SM · $A_CP$ in $D^0 →ππ/KK$ · 0.93

Uses data or values from 1 paper

The combined value leads to a world average [ref] [equation] where [equation] is a shorthand for the time integrated CP-asymmetry, for a case where the final state $f$ is a CP-eigenstate. $ΔA_CP$ is a convenient quantity since systematic experimental errors cancel.

Measurement of CP--violating asymmetries in D0 --> pi+ pi- and D0 --> K+K- decays at CDF · $A_CP$ in $D^0 →ππ/KK$ · 0.91

Cites as background 6 papers

We write the amplitude as follows [The amplitudes $A_1,2$ up to phases are often denoted by $A_PC, PV$ in the literature e.g. [ref] .

Shedding light on CP violation in the charm system via D to V gamma decays · $D →V γ$ transitions · 0.99
The general formulae and a derivation, including TDCP-asymmetries, can be found in Ref. [ref] for example.

Exploiting the width difference in B_s -> phi gamma · Direct CP-violation · 0.83
Other channels and effects that were proposed are the electric dipole moment of the nucleon [ref] ,

Direct CP violation in charm and flavor mixing beyond the SM · $A_CP$ in $D^0 →V γ$ · 0.96

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