Spontaneous CP violating phase as the CKM matrix phase

Physical Review D, 2006

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson φ in γγ → ff , f = τ /t, from that of the QED continuum. This can help in getting information on the γγφ coupling in case φ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case φ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters. In particular, the method suggested can cover the region where a light Higgs boson may have been missed by LEP due to CP violation in the Higgs sector, and may be missed as well at the LHC.

Physics Letters B, 1990

The calculation of neutron EDM due to the exchange of neutral Higgs bosons is reconsidered. We find that, contrary to previous claims, both the scalar and the pseudoscalar Higgs nucleon couplings are not dominated by the heavy-quark contributions. The relevant pseudoscalar coupling is calculated by using the recent EMC data on the nucleon matrix element of the axial vector current; the scalar coupling incorporates the information contained in the nN sigma-term. The need for a proper treatment of the strange quark operators between the nucleon states is emphasized.

Phys Rev D, 2006

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson φ in γγ → ff , f = τ /t, from that of the QED continuum. This can help in getting information on the γγφ coupling in case φ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case φ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters. In particular, the method suggested can cover the region where a light Higgs boson may have been missed by LEP due to CP violation in the Higgs sector, and may be missed as well at the LHC.

Physical Review D, 1982

Work by Deshpande and Sanda, which appears to invalidate Higgs-boson-exchange models of CP noninvariance, is buttressed by (i) use of the MIT bag model to calculate matrix elements, (ii) use of experimental rather than calculated riumbers for the K~2m decay amplitude and the KL-Eq mass difference, and {iii) inclusion of possible t-quark effects. We conclude that, barring accidental cancellations, such Higgs-boson-exchange models are incompatible with experiment.

Pramana, 2007

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson φ in γγ → ff , f = τ /t, from that of the QED continuum. This can help in getting information on the γγφ coupling in case φ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case φ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters. In particular, the method suggested can cover the region where a light Higgs boson may have been missed by LEP due to CP violation in the Higgs sector, and may be missed as well at the LHC.

2008

The non-minimal flavour violating interactions of mirror quarks and new heavy gauge bosons in the Littlest Higgs model with T-parity (LHT) give rise to naturally large CP-violating effects in the B s system. In view of a large new CP phase in B s −B s mixing hinted by the CDF and DØ data and the recent UTfit analysis, we update our 2006 analysis of particle-antiparticle mixing and rare K and B decays in the LHT model, using the most recent values of a number of input parameters and performing a more careful error analysis. We find that the CP-asymmetry S ψφ can easily reach values ∼ 0.15 − 0.20, compared to the SM value ∼ 0.04, while higher values are rather unlikely though not excluded. Large enhancements are also possible in the branching ratios for K L → π 0 νν, K + → π + νν and K L → π 0 ℓ + ℓ − with much more modest effects in B s,d → µ + µ − . We perform a detailed study of correlations between the latter decays and S ψφ as well as of the correlation between S ψφ and S ψK S . We also point out that the possible tension between ε K and the tree level CKM determination recently hinted by various analyses can easily be resolved in the LHT model.

Pramana J Phys, 2007

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson φ in γγ → ff , f = τ /t, from that of the QED continuum. This can help in getting information on the γγφ coupling in case φ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case φ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters. In particular, the method suggested can cover the region where a light Higgs boson may have been missed by LEP due to CP violation in the Higgs sector, and may be missed as well at the LHC.

Journal of High Energy Physics, 2010

We compare the effectiveness of two hypotheses, Natural Flavour Conservation (NFC) and Minimal Flavour Violation (MFV), in suppressing the strength of flavour-changing neutral-currents (FCNCs) in models with more than one-Higgs doublet. We show that the MFV hypothesis, in its general formulation, is more stable in suppressing FCNCs than the hypothesis of NFC alone when quantum corrections are taken into account. The phenomenological implications of the two scenarios are discussed analysing meson-antimeson mixing observables and the rare decays B s,d → µ + µ − . We demonstrate that, introducing flavour-blind CP phases, two-Higgs doublet models respecting the MFV hypothesis can accommodate a large CP-violating phase in B s mixing, as hinted by CDF and D0 data and, without extra free parameters, soften significantly in a correlated manner the observed anomaly in the relation between ε K and S ψK S . of renormalizable couplings contributing at the tree-level to FCNC processes, in multi-Higgs models, goes under the name of Natural Flavour Conservation (NFC) hypothesis.

Physical Review D, 2011

We study an extension of the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM), considering the effects of new degrees of freedom at the TeV scale, and allowing for sources of CP violation beyond the MSSM (BMSSM). We analyze the impact of the BMSSM sources of CP violation on the Higgs collider phenomenology and on low energy flavor and CP violating observables. We identify distinct Higgs collider signatures that cannot be realized, either in the case without CP violating phases or in the CP violating MSSM, and investigate the prospects to probe them at the Tevatron and the LHC. The most striking benchmark scenario has three neutral Higgs bosons that all decay dominantly into W boson pairs and that are well within the reach of the 7 TeV LHC run. On the other hand, we also present scenarios with three Higgs bosons that have masses M Hi 150 GeV and decay dominantly into bb. Such scenarios are much more challenging to probe and can even lie completely outside the reach of the 7 TeV LHC run. We explore complementary scenarios with standard MSSM Higgs signals that allow to accommodate a sizable B s mixing phase as indicated by D0, as well as the excess in B s → µ + µ − candidates recently reported by CDF. We find that, in contrast to the MSSM, a minimal flavor violating soft sector is sufficient to generate significant corrections to CP violating observables in meson mixing, compatible with EDM constraints. In particular, a sizable B s mixing phase, S ψφ 0.4, can be achieved for specific regions of parameter space. Such a large B s mixing phase would unambiguously imply a sizable suppression of S ψK S with respect to the SM prediction and a BR(B s → µ + µ − ) close to the 95 % C.L. upper bound reported by CDF.

Physical Review D, 2011

Little Higgs models often feature spontaneously broken extra global symmetries, which must also be explicitly broken in order to avoid massless Goldstone modes in the spectrum. We show that a possible conflict with collective symmetry breaking then implies light modes coupled to the Higgs boson, leading to interesting phenomenology. Moreover, spontaneous CP violation is quite generic in such cases, as the explicit breaking may be used to stabilize physical CP odd phases in the vacuum. We demonstrate this in an SU(2)×SU(2)×U(1) variant of the Littlest Higgs, as well as in an original SU(6)/SO(6) model. We show that even a very small explicit breaking may lead to large phases, resulting in new sources of CP violation in this class of models.