Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalously large ${\cal O}_8$ and long-distance chirality from $A_{\rm
  CP}[D^0 \to (\rho^0,\omega) \gamma](t)$   A large CP-asymmetry $\Delta A_{\rm CP}$ has been reported in the $D^0 \to
\pi^+\pi^-/K^+K^-$ system. At present it remains unclear whether this is due to
incalculable strong interaction matrix elements or genuine new physics (NP).
Amongst the latter a new weak phase in the chromomagnetic operator ${\cal O}_8$
has emerged as a promising candidate. Extending earlier ideas we show that the
interference of long-distance (LD) terms with the ${\cal O}_8$ matrix element,
which has a large strong phase, gives rise to direct CP-violation at the level
of a few percent in $D^0 \to (\rho^0,\omega) \gamma$ and $D^+_{(d,s)} \to
(\rho^+,K^{*+}) \gamma$ for reference values $ {\rm Im}[C_8^{NP}] \simeq 0.4
\cdot 10^{-2}$. This is two orders of magnitude above a Standard Model (SM)
estimate. The contribution of $ {\rm Im}[C_7^{NP}]$, which is dependent on the
model of NP, is governed by the LD strong phase which vanishes in the chiral
limit at leading order. The question of whether this is significantly changed
by radiative corrections is an open and interesting question that we discuss.
Furthermore we point out that the relative size of left- and right-handed
(photon polarisation)-LD amplitudes can be measured, in principle, through
time-dependent CP (TDCP) asymmetries in the case where they are both sizeable
which is supported by SM estimates. Thus determination of the latter provides
interesting information on the LD-chirality independent of NP. We comment on
the origin of the LD contribution, which we believe to be dominated by weak
annihilation (WA), in the appendix.

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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci