Cornering Spontaneous CP Violation with Charged-Higgs Searches

Abstract

Decades of precision measurements have firmly established the Kobayashi-Maskawa phase as the dominant source of the charge-parity (CP) violation observed in weak quark decays. However, it is still unclear whether CP violation is explicitly encoded in complex Yukawa matrices or instead stems from spontaneous symmetry breaking with underlying CP-conserving Yukawa and Higgs sectors.Here we study the latter possibility for the case of a generic two-Higgs-doublet model (2HDM). We find that theoretical constraints limit the ratio t β of the vacuum expectation values (vevs) to the range 0.22 ≤ t β ≤ 4.5 and imply the upper bounds M H ± ≤ 435 GeV, M H 0 2 ≤ 485 GeV and M H 0 3 ≤ 545 GeV for the charged and extra neutral Higgs masses. We derive lower bounds on charged-Higgs couplings to bottom quarks which provide a strong motivation to study the nonstandard production and decay signatures pp → qbH ± (→ q b) with all flavors q, q = u, c, t in the search for the charged Higgs boson. We further present a few benchmark scenarios with interesting discovery potential in collider analyses.

The charged Higgs from the Bottom-Up: probing flavor at the LHC

“…Specific pattern of flavor violation have been employed in numerous scenarios motivated by outstanding theoretical problems and/or experimental anomalies. Flavor-changing couplings of light additional Higgs fields have been considered for example in QCD axion models (accounting for both Strong CP and DM) [10,11], scenarios of Electroweak Baryogenesis [12][13][14][15], and models addressing fermion mass hierarchies [16][17][18][19][20][21] or the origin of CP violation in the Yukawa sector [22,23]. Similar setups have been used to explain the anomalous magnetic moment of the muon [24][25][26] or the various anomalies observed in semi-leptonic B-meson decays [27][28][29][30][31][32][33].…”

“…(1.1) is provided by the class of models in ref. [23], which induces the CKM phase by spontaneous CP violation at the electroweak scale. Interestingly, this implies both an upper bound on the charged Higgs mass of about 430 GeV and a lower bound on its couplings to b-quarks, max(|g tb |, |g cb |, |g ub |) ≥ 0.20.…”