25 research outputs found
Large Higgs-electron Yukawa coupling in 2HDM
The present upper bound on , the ratio between the electron Yukawa
coupling and its Standard Model value, is of . We ask what would
be the implications in case that is close to this upper bound. The
simplest extension that allows for such enhancement is that of two Higgs
doublet models (2HDM) without natural flavor conservation. In this framework,
we find the following consequences: (i) Under certain conditions, measuring
and would be enough to predict values of Yukawa couplings
for other fermions and for the and scalars. (ii) In the case that the
scalar potential has a softly broken symmetry, the second Higgs doublet
must be light, but if there is hard breaking of the symmetry, the second Higgs
doublet can be much heavier than the electroweak scale and still allow the
electron Yukawa coupling to be very different from its SM value. (iii) CP must
not be violated at a level higher than in both the
scalar potential and the Yukawa sector. (iv) LHC searches for
resonances constrain this scenario in a significant way. Finally, we study the
implications for models where one of the scalar doublets couples only to the
first generation, or only to the third generation.Comment: 14 pages, 2 figure
Probing the Rule in Three Body Charm Decays
CP violation in charm decay was observed in the decays of a meson to two pseudoscalars. When interpreted within
the SM, the results imply that the ratio of the relevant rescattering
amplitudes has a magnitude and phase that are both of . We discuss ways
to probe similar ratios in decays, where is
a vector that decays to two pseudoscalars, from the Dalitz-plot analysis of
time-integrated three-body decays. Compared to two-body decays, three-body
decays have the advantage that the complete system can be solved without the
need for time-dependent CP violation measurements or use of correlated
-- production. We discuss the decays and as examples by considering a
toy model of only two overlapping charged resonances, treating the underlying
pseudo two-body decays in full generality.Comment: 32 pages. Additional references and clarifications. Conclusions
unchanged. Matches published versio
A Precision Relation between and
We find that the phase appearing in the unitarity relation between
and is equal to the phase shift in the interference term of the
time-dependent decay. A probe of this relation at
future kaon facilities constitutes a Standard Model test with a theory
precision of about . The phase has further importance for sensitivity
studies regarding the measurement of the time-dependent decay rate to extract the CKM matrix element combination . We find a
model-independent theoretically clean prediction, . The quoted error is a combination of the theoretical and experimental
errors, and both of them are expected to shrink in the future. Using input from
the large- limit within chiral perturbation theory, we find a theory
preference towards solutions with negative , reducing a
four-fold ambiguity in the angle to a two-fold one
Probing the ∆ U = 0 rule in three body charm decays
From Springer Nature via Jisc Publications RouterHistory: received 2021-01-23, rev-recd 2021-04-01, accepted 2021-04-28, collection 2021-05, registration 2021-05-20, pub-electronic 2021-05-20, online 2021-05-20Publication status: PublishedAbstract: CP violation in charm decay was observed in the decays D0→ P±P∓ of a D0 meson to two pseudoscalars. When interpreted within the SM, the results imply that the ratio of the relevant rescattering amplitudes has a magnitude and phase that are both of O(1). We discuss ways to probe similar ratios in D0→ V±P∓ decays, where V is a vector that decays to two pseudoscalars, from the Dalitz-plot analysis of time-integrated three-body decays. Compared to two-body decays, three-body decays have the advantage that the complete system can be solved without the need for time-dependent CP violation measurements or use of correlated D0−D¯0 production. We discuss the decays D0→ π+π−π0 and D0→ K+K−π0 as examples by considering a toy model of only two overlapping charged resonances, treating the underlying pseudo two-body decays in full generality