Mixing CP Research Articles

Lepton mixing parameters from Δ(48) family symmetry and generalised CP

We provide a systematic and thorough exploration of the Δ(48) family symmetry and the consistent generalised CP symmetry. A model-independent analysis of the achievable lepton flavor mixing is performed by considering all the possible remnant symmetries in the neutrino and the charged lepton sectors. We find a new interesting mixing pattern in which both lepton mixing angles and CP phases are nontrivial functions of a single parameter θ. The value of θ can be fixed by the measured reactor mixing angle θ 13, and the excellent agreement with the present data can be achieved. A supersymmetric model based on Δ(48) family symmetry and generalised CP symmetry is constructed, and this new mixing pattern is exactly reproduced.

A model of quark and lepton mixing

We propose a model of quark and lepton mixing based on the tetrahedral A(4) family symmetry with quark-lepton unification via the tetra-colour Pati-Salam gauge group SU(4)_{PS}, together with SU(2)_L x U(1)_R. The "tetra-model" solves many of the flavour puzzles and remarkably gives ten predictions at leading order, including all six PMNS parameters. The Cabibbo angle is approximately given by 1/4, due to the tetra-vacuum alignment (1,4,2), providing the Cabibbo connection between quark and lepton mixing. Higher order corrections are responsible for the smaller quark mixing angles and CP violation and provide corrections to the Cabibbo and lepton mixing angles and phases. The tetra-model involves an SO(10)-like pattern of Dirac and heavy right-handed neutrino masses, with the strong up-type quark mass hierarchy cancelling in the see-saw mechanism, leading to a normal hierarchy of neutrino masses with an atmospheric angle in the first octant of 40 +/- 1 degree, a solar angle of 34 +/- 1 degree, a reactor angle of 9.0 +/- 0.5 degree, depending on the ratio of neutrino masses m_2/m_3, and a Dirac CP violating oscillation phase of 260 +/- 5 degrees.

Minimal weak basis textures and quark mixing data

The phenomenology of the most general quark mass matrices with a minimum of three texture zeros obtained through weak basis (WB) transformations has been discussed within the framework of the standard model. The relationship between the textures, naturalness and WB transformations has also been studied. Adopting a ‘hierarchical’ parameterization for the quark mass matrix, we have detailed exact relations for the various elements of the quark mixing matrix along with the CP asymmetry angle β, illustrating the explicit relationship between the observed hierarchies among the WB quark mass matrices and the quark mixing matrix. Besides exploring the complete parameter space available to the (Mq)11, (q = u, d) elements in these mass matrices, their implications for quark mixing data and CP violation asymmetries have also been explored.

Lepton mixing parameters from discrete and CP symmetries

We consider a scenario with three Majorana neutrinos in which a discrete, finite flavour group G f is combined with a generalized CP transformation. We derive conditions for consistently defining such a setup. We show that in general lepton mixing angles and CP phases (Dirac as well as Majorana) only depend on one single parameter θ which can take values between 0 and π, if the residual symmetries are G e ⊂ G f in the charged lepton and G ν = Z 2 × CP in the neutrino sector. We perform a comprehensive study for G f = S 4 and find five cases which are phenomenologically interesting. They naturally lead to a non-zero reactor mixing angle and all mixing parameters are strongly correlated. Some of the patterns predict maximal atmospheric mixing and maximal Dirac phase, while others predict trivial Dirac and Majorana phases.

Neutrino mixing and geometric CP violation with [formula omitted] symmetry

Predictive spontaneous CP violation is possible if it is obtained geometrically through a non-Abelian discrete symmetry. I propose such a model of neutrino mass and mixing based on Δ(27).

THEORETICAL OVERVIEW ON THE FLAVOR ISSUES OF MASSIVE NEUTRINOS

We present an overview on some basic properties of massive neutrinos and focus on their flavor issues, including the mass spectrum, flavor mixing pattern and CP violation. The lepton flavor structures are explored by taking into account of the observed value of the smallest neutrino mixing angle θ13. The impact of θ13 on the running behaviors of other flavor mixing parameters is discussed in some detail. The seesaw-induced enhancement of the electromagnetic dipole moments for three Majorana neutrinos is also discussed in a TeV seesaw scenario.

Models and Phenomenology of Neutrino Masses circa 2010

We review recent developments in models of neutrino masses and mixing. Emphases are given to models based on finite group family symmetries from which the tri-bimaximal neutrino mixing can arise. In particular, we describe one recent model based on SUSY SU(5) combined with a family symmetry based on the double tetrahedral group, T′. All 22 observable fermion masses and mixing angles and CP violating measures are fitted with only 9 parameters. In this model, a near tri-bimaximal MNS matrix and a realistic CKM matrix are simultaneously generated; the MNS matrix gets slightly modified by virtue of having the Georgi-Jarlskog relations. Due to the presence of complex Clebsch-Gordan coefficients in T′, CP violation in this model is entirely geometrical in origin. The prediction of the model for the leptonic Dirac CP phase is 227°, which turns out to be very close to the current best fit value of 220° from SuperK.

Anarchy and leptogenesis

We study if leptogenesis works successfully together with the neutrino mass anarchy hypothesis. We find that the predicted neutrino mass spectrum is sensitive to the reheating temperature or the inflaton mass, while the distributions of the neutrino mixing angles and CP violation phases remain intact as determined by the invariant Haar measure of U(3). In the case of thermal leptogenesis, the light neutrino mass distribution agrees well with the observations if the reheating temperature is O(10^{9-11}) GeV. The mass spectrum of the right-handed neutrinos and the neutrino Yukawa matrix exhibit a certain pattern, as a result of the competition between random matrices with elements of order unity and the wash-out effect. Non-thermal leptogenesis is consistent with observation only if the inflaton mass is larger than or comparable to the typical right-handed neutrino mass scale. Cosmological implications are discussed in connection with the 125GeV Higgs boson mass.

Measurement of mixing and CP violation parameters in two-body charm decays

Abstract A study of mixing and indirect CP violation in D 0 mesons through the determination of the parameters y CP and A Γ is presented. The parameter y CP is the deviation from unity of the ratio of effective lifetimes measured in D 0 decays to the CP eigenstate K + K − with respect to decays to the Cabibbo favoured mode K −π+. The result measured using data collected by LHCb in 2010, corresponding to an integrated luminosity of 29 pb−1, is y CP = (5.5 ± 6.3stat ± 4.1syst) × 10−3. The parameter A Γ is the asymmetry of effective lifetimes measured in decays of D 0 and $ {\overline D^0} $ mesons to K + K −. The result is A Γ = (−5.9 ± 5.9stat ± 2.1syst) × 10−3. A data-driven technique is used to correct for lifetime-biasing effects.

The reactor mixing angle and CP violation with two texture zeros in the light of T2K

We reconsider the phenomenological implications of two texture zeros in symmetric neutrino mass matrices in the light of the recent T2K results for the reactor angle and the new global analysis which gives also best fit values for the Dirac CP phase δ. The most important results of the analysis are: Among the viable cases classified by Frampton et al. only A 1 and A 2 predict θ 13 to be different from zero at 3 σ. Furthermore these two cases are compatible only with a normal mass spectrum in the allowed region for the reactor angle. At the best fit value A 1 and A 2 predict 0.024 ⩾ sin 2 θ 13 ⩾ 0.012 and 0.014 ⩽ sin 2 θ 13 ⩽ 0.032 , respectively, where the bounds on the right and the left correspond to cos δ = − 1 and cos δ = 1 , respectively. The cases B 1, B 2, B 3 and B 4 predict nearly maximal CP violation, i.e. cos δ ≈ 0 .

Studies of CP Violation and Mixing in the D Mesons decays from BABAR

After an introduction on the mixing and CP violation (CPV) in the neutral charmed mesons system, we present the current status of the measurements. We discuss some recent analyses performed on the data sample collected by the BABAR detector at the PEPII e+e− asymmetric collider.

Sizeable θ 13 from the charged lepton sector in SU(5), (tri-)bimaximal neutrino mixing and Dirac CP violation

The recent results from T2K and MINOS experiments point towards a relatively large value of the reactor angle \theta_13 in the lepton sector. In this paper we show how a large \theta_13 can arise from the charged lepton sector alone in the context of an SU(5) GUT. In such a scenario (tri-)bimaximal mixing in the neutrino sector is still a viable possibility. We also analyse the general implications of the considered scenario for the searches of CP violation in neutrino oscillations.

Flavour mixing of neutrinos and baryon asymmetry of the universe

We investigate baryogenesis in the νMSM, which is the Minimal Standard Model (MSM) extended by three right-handed neutrinos with Majorana masses smaller than the weak scale. In this model the baryon asymmetry of the universe (BAU) is generated via flavour oscillation between right-handed neutrinos. We consider the case when BAU is solely originated from the CP violation in the mixing matrix of active neutrinos. We perform analytical and numerical estimations of the yield of BAU, and show how BAU depends on mixing angles and CP violating phases. It is found that the asymmetry in the inverted hierarchy for neutrino masses receives a suppression factor of about 4% comparing with the normal hierarchy case. It is, however, pointed out that, when θ13=0 and θ23=π/4, baryogenesis in the normal hierarchy becomes ineffective, and hence the inverted hierarchy case becomes significant to account for the present BAU.

Comparing trimaximal mixing and its variants with deviations from tri-bimaximal mixing

We analyze in detail the predictions of “trimaximal” neutrino mixing, which is defined by a mixing matrix with identical second column elements. This column is therefore identical to the second column in the case of tri-bimaximal mixing. We also generalize trimaximal mixing by assuming that the other rows and columns of the mixing matrix individually can have the same forms as for tri-bimaximal mixing. The phenomenology of these alternative scenarios and their mixing angle and CP phase correlations are studied. We emphasize how trimaximal mixing scenarios can be distinguished experimentally from broken tri-bimaximal mixing.

Chapter 26 CP and T Violation

The following sections are included: Formalism and Review CP Violation in [Formula: see text] Mixing CP Violation in Decay CP Violation in the Interference Between Decays With and Without Mixing Rate of the CP Violation in the Coherent [Formula: see text] Pair T Violation

Prospects for New Physics in rare decays, mixing and related CP violation at LHCb

The LHCb experiment currently constructed at CERN has been designed to perform precision measurements on CP asymmetries and to measure rare decays of B mesons. We discuss some selected key measurements to demonstrate the potential of LHCb to find New Physics beyond the Standard Model.

Probing CP-violating Higgs contributions in γγ → f % MathType!MTEF!2!1!+- % feaafiart1ev1aaatCvAUfKttLearuqr1ngBPrgarmWu51MyVXgatC % vAUfeBSjuyZL2yd9gzLbvyNv2CaeHbd9wDYLwzYbItLDharyavP1wz % ZbItLDhis9wBH5garqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbb % L8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yqaqpe % pae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabeqaam % aaeaqbaaGcbaGafmOzayMbaebaaaa!3C38! $$ \bar f $$

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 → f\( \bar f \), 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.

ProbingCP-violating Higgs contributions inγγ→ff¯through fermion polarization

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 {phi} in {gamma}{gamma}{yields}ff, f={tau}/t, from that of the QED continuum. This can help in getting information on the {gamma}{gamma}{phi} coupling in case {phi} is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case {phi} has indeterminate CP. Furthermore, we take the minimal supersymmetric standard model (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.

CP violation in supersymmetry, Higgs sector and the large hadron collider

n this talk I discuss some aspects of CP violation (CPV) in supersymmetry (SUSY) as well as in the Higgs sector. Further, I discuss ways in which these may be probed at hadronic colliders. In particular I will point out the ways in which studies in the (chi) over tilde (+/-), (chi) over tilde (0)(2) sector at the Tevatron may be used to provide information on this and how the search can be extended to the LHC. I will then follow this by a discussion of the CP mixing induced in the Higgs sector due to the above-mentioned CPV in the soft SUSY breaking parameters and its effects on the Higgs phenomenology at the LHC. I would then point out some interesting aspects of the phenomenology of a moderately light charged Higgs boson, consistent with the LEP constraints, in this scenario. Decay of such a charged Higgs boson would also allow a probe of a light (less than or similar to 50 GeV), CP-violating (CPV) Higgs boson. Such a light neutral Higgs boson might have escaped detection at LEP and could also be missed at the LHC in the usual search channels.

Erratum: Bounds on the neutrino mixing angles andCPphase for anSO(10)model with lopsided mass matrices [Phys. Rev. D72, 013001 (2005)

The bounds on the neutrino mixing angles and CP Dirac phase for an SO(10) model with lopsided mass matrices, arising from the presence of ${\bf 16}_H$ and $\bar{\bf 16}_H$ Higgs representations, are studied by variation of the one real and three unknown complex input parameters for the right-handed Majorana neutrino mass matrix. The scatter plots obtained favor nearly maximal atmospheric neutrino mixing, while the reactor neutrino mixing lies in the range $10^{-5} \lsim \sin^2 \theta_{13} \lsim 1 \times 10^{-2}$ with values greater than $10^{-3}$ most densely populated. A rather compelling scenario within the model follows, if we restrict the three unknown complex parameters to their imaginary axes and set two of them equal. We then find the scatter plots are reduced to narrow bands, as the mixing angles and CP phase become highly correlated and predictive. The bounds on the mixing angles and phase then become $0.45 \lsim \sin^2 \theta_{23} \lsim 0.55$, $0.38 \lsim \tan^2 \theta_{12} \lsim 0.50$, $0.002 \lsim \sin^2 \theta_{13} \lsim 0.003$, and $60^\circ \lsim \pm \delta_{CP} \lsim 85^\circ$. Moreover, successful leptogenesis and subsequent baryogenesis are also obtained, with $\eta_B$ increasing from $(2.7 to 6.3) \times 10^{-10}$ as $\sin^2 \theta_{23}$ increases from 0.45 to 0.55.