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. 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 AE ≤ 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 AE ð→ q 0 bÞ with all flavors q; q 0 ¼ 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.
We study a class of DFSZ-like models for the QCD axion that can address observed anomalies in stellar cooling. Stringent constraints from SN1987A and neutron stars are avoided by suppressed couplings to nucleons, while axion couplings to electrons and photons are sizable. All axion couplings depend on few parameters that also control the extended Higgs sector, in particular lepton flavor-violating couplings of the Standard Model-like Higgs boson h. This allows us to correlate axion and Higgs phenomenology, and we find that BR(h → τe) can be as large as the current experimental bound of 0.22%, while BR(h → μμ) can be larger than in the Standard Model by up to 70%. Large parts of the parameter space will be tested by the next generation of axion helioscopes such as the IAXO experiment.
Searches for New Physics focus either on the direct production of new particles at colliders or at deviations from known observables at low energies. In order to discover New Physics in precision measurements, both experimental and theoretical uncertainties must be under full control. Laser spectroscopy nowadays offers a tool to measure transition frequencies very precisely. For certain molecular and atomic transitions the experimental technique permits a clean study of possible deviations. Theoretical progress in recent years allows us to compare ab initio calculations with experimental data. We study the impact of a variety of New Physics scenarios on these observables and derive novel constraints on many popular generic Standard Model extensions. As a result, we find that molecular spectroscopy is not competitive with atomic spectroscopy and neutron scattering to probe new electron-nucleus and nucleus-nucleus interactions, respectively. Molecular and atomic spectroscopy give similar bounds on new electron-electron couplings, for which, however, stronger bounds can be derived from the magnetic moment of the electron. In most of the parameter space H$$_2$$ 2 molecules give stronger constraints than T$$_2$$ 2 or other isotopologues.
We systematically study model-independent constraints on the three generic charged Higgs couplings to b-quarks and up-type quarks. While existing LHC searches have focussed on the tb coupling, we emphasize that the LHC plays a crucial role in probing also ub and cb couplings, since constraints from flavor physics are weak. In particular we propose various new searches that can significantly extend the present reach on the parameter space by: i) looking for light charged Higgses that decay into ub-quarks, ii) probing charged Higgs couplings to light and top quarks using multi-b-jet signatures, iii) looking for single b-quarks in low-mass dijet searches, iv) searching for charge asymmetries induced by charged Higgs production via ub couplings.
We systematically study model-independent constraints on the three generic charged Higgs couplings to b-quarks and up-type quarks. While existing LHC searches have focussed on the tb coupling, we emphasize that the LHC plays a crucial role in probing also ub and cb couplings, since constraints from flavor physics are weak. In particular we propose various new searches that can significantly extend the present reach on the parameter space by: i) looking for light charged Higgses that decay into ub-quarks, ii) probing charged Higgs couplings to light and top quarks using multi-b-jet signatures, iii) looking for single b-quarks in low-mass dijet searches, iv) searching for charge asymmetries induced by charged Higgs production via ub couplings.
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