TY  - EJOUR
AU  - Bonnefoy, Quentin
AU  - Gendy, Emanuele
AU  - Grojean, Christophe
AU  - Ruderman, Joshua T.
TI  - Opportunistic CP Violation
IS  - DESY-23-018
M1  - PUBDB-2023-00700
M1  - DESY-23-018
M1  - arXiv:2302.07288
M1  - HU-EP-22/39
M1  - TUM-HEP-1453/23
PY  - 2023
N1  - Now published on the arXiv: https://arxiv.org/abs/2302.07288
AB  - In the electroweak sector of the Standard Model, CP violation arises through a very particular interplay between the three quark generations, as described by the Cabibbo-Kobayashi-Maskawa (CKM) mechanism and the single Jarlskog invariant J<sub>4</sub>. Once generalized to the Standard Model Effective Field Theory (SMEFT), this peculiar pattern gets modified by higher-dimensional operators, whose associated Wilson coefficients are usually split into CP-even and odd parts. However, CP violation at dimension four, i.e., at the lowest order in the EFT expansion, blurs this distinction: any Wilson coefficient can interfere with J<sub>4</sub> and mediate CP violation. In this paper, we study such interferences at first order in the SMEFT expansion, O(1/Λ<sup>2</sup>), and we capture their associated parameter space via a set of 1551 linear CP-odd flavor invariants. This construction describes both new, genuinely CP-violating quantities as well as the interference between J<sub>4</sub> and CP-conserving ones. We call this latter possibility opportunistic CP violation. Relying on an appropriate extension of the matrix rank to Taylor expansions, which we dub Taylor rank, we define a procedure to organize the invariants in terms of their magnitude, so as to retain only the relevant ones at a given precision. We explore how this characterization changes when different assumptions are made on the flavor structure of the SMEFT coefficients. Interestingly, some of the CP-odd invariants turn out to be less suppressed than J<sub>4</sub>, even when they capture opportunistic CPV, demonstrating that CP-violation in the SM, at dimension 4, is accidentally small.
KW  - CP, violation (INSPIRE)
KW  - dimension, 4 (INSPIRE)
KW  - operator, higher-dimensional (INSPIRE)
KW  - capture (INSPIRE)
KW  - interference (INSPIRE)
KW  - flavor (INSPIRE)
KW  - effective field theory (INSPIRE)
KW  - mediation (INSPIRE)
KW  - structure (INSPIRE)
KW  - electroweak interaction (INSPIRE)
KW  - quark (INSPIRE)
KW  - Jarlskog (INSPIRE)
KW  - suppression (INSPIRE)
KW  - Taylor expansion (INSPIRE)
LB  - PUB:(DE-HGF)25
DO  - DOI:10.3204/PUBDB-2023-00700
UR  - https://bib-pubdb1.desy.de/record/570353
ER  -