The emergence of the ΔU = 0 rule in charm physics

Grossman, Yuval; Schacht, Stefan

doi:10.1007/jhep07(2019)020

Cited by 65 publications

(75 citation statements)

References 80 publications

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“…Note added. After this work was finished two paper appeared on the arXiv [85,86] attributing the new LHCb measurement of ∆A CP to SM effects. We acknowledge the line of thought in these two papers, but we do not see the necessity for assuming an O(10) enhancement of hadronic effects over the perturbative SM estimate, even if this assumption is self-consistent.…”

Section: Jhep07(2019)161mentioning

confidence: 99%

ΔACP within the Standard Model and beyond

Chala

Lenz

Rusov

et al. 2019

J. High Energ. Phys.

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In light of the recent LHCb observation of CP violation in the charm sector, we review standard model (SM) predictions in the charm sector and in particular for ∆A CP. We get as an upper bound in the SM |∆A SM CP | ≤ 3.6 × 10 −4 , which can be compared to the measurement of ∆A LHCb2019 CP = (−15.4 ± 2.9) × 10 −4. We discuss resolving this tension within an extension of the SM that includes a flavour violating Z that couples only toss andcu. We show that for masses below 80 GeV and flavour violating coupling of the order of 10 −4 , this model can successfully resolve the tension and avoid constraints from dijet searches, D 0 − D 0 mixing and measurements of the Z width.

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Section: Jhep07(2019)161mentioning

confidence: 99%

ΔACP within the Standard Model and beyond

Chala

Lenz

Rusov

et al. 2019

J. High Energ. Phys.

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“…Only recently has CP violation been observed in the decay of charmed mesons [11]. The limited precision of the SM predictions, together with the limited amount of experimental information available [12], is, however, not yet sufficient to establish whether the observed signal could be explained by the SM [13][14][15][16][17][18]. Additional searches for CP violation in the charm sector, and particularly for more suppressed and yet-to-be-observed signs of CP-violating effects induced by D 0 -D 0 mixing, have unique potential to probe for the existence of beyond-the-SM dynamics, which couple preferentially to up-type quarks [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Updated measurement of decay-time-dependent CP asymmetries in D0→K+

Aaij¹,

Beteta²,

Ackernley³

et al. 2020

Phys. Rev. D

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A search for decay-time-dependent charge-parity (CP) asymmetry in D 0 → K þ K − and D 0 → π þ π − decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of 5.4 fb −1. The D 0 mesons are required to originate from semileptonic decays of b hadrons, such that the charge of the muon identifies the flavor of the neutral D meson at production. The asymmetries in the effective decay widths of D 0 andD 0 mesons are determined to be A Γ ðK þ K − Þ ¼ ð−4.3 AE 3.6 AE 0.5Þ × 10 −4 and A Γ ðπ þ π − Þ ¼ ð2.2 AE 7.0 AE 0.8Þ × 10 −4 , where the uncertainties are statistical and systematic, respectively. The results are consistent with CP symmetry and, when combined with previous LHCb results, yield A Γ ðK þ K − Þ ¼ ð−4.4 AE 2.3 AE 0.6Þ × 10 −4 and A Γ ðπ þ π − Þ ¼ ð2.5 AE 4.3 AE 0.7Þ × 10 −4 .

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“…The size of this asymmetry is larger than the naive SM expectation |∆a dir CP | ≤ 3 × 10 −4 [26,27], based on perturbative QCD or light-cone sum rules estimates. However, the measured value could be explained within the SM with non-perturbative re-scattering effects of moderate size that enhance the U-spin invariant decay amplitude [28]. A direct CP asymmetry necessarily involves a non-zero strong phase-shift difference between (at least) two interfering amplitudes.…”

Section: Direct Cp Violation In Charmmentioning

confidence: 93%

Flavour Anomalies

Pich¹

2019

Proceedings of 7th Annual Conference on Large Hadron Collider Physics — PoS(LHCP2019)

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The experimental data on b → cτν τ and b → s + − transitions exhibit sizeable discrepancies with the Standard Model expectations. We present an overview of the present status and discuss possible interpretations within a model-independent effective Lagrangian approach. We also briefly elaborate on some other claimed flavour anomalies such as the recently observed CP asymmetry in D 0 decays or the K 0 → ππ ratio ε K /ε K. The Standard Model prediction for the direct CPviolating ratio ε K /ε K agrees with its measured value, once all theoretical ingredients are correctly taken into account.

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The emergence of the ΔU = 0 rule in charm physics

Cited by 65 publications

References 80 publications

ΔACP within the Standard Model and beyond

ΔACP within the Standard Model and beyond

Updated measurement of decay-time-dependent CP asymmetries in D0→K+

Flavour Anomalies

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