B-decay CP-asymmetries in SUSY with a U(2)3 flavour symmetry

If the current acceleration of our Universe is due to a cosmological constant, then a Coleman–De Luccia bubble will nucleate in our Universe. In this work, we consider that our observations could be likely in this framework, consisting of two infinite spaces, if a foliation by constant mean curvature hypersurfaces is taken to count the events in the spacetime. Thus, we obtain and study a particular foliation, which covers the existence of most observers in our part of spacetime.     

Global family symmetry and CP violation

CP-violation is discussed in a model with a global axial family symmetry. The family symmetry is identified with a Peccei-Quinn symmetry to solve the strong CP Problem. It is pointed out that weak CP-nonconservation is a consequence of the Higgs singlet which is needed to render the axion invisible. The model predicts reasonable masses and mixing angles for the fermions.     

Superconformal supergravity and internal symmetry

The Weyl-like gauging of Wess-Zumino superconformal symmetry and of its internal symmetric generalizations SU(2,2|N) are treated. The prolification of gauge fields is much more modest than in super-Riemannian theories. Unlike supergravity, a field theory of this type is still a unified theory that provides its own sources.     

Chaotic inflation in supergravity with Heisenberg symmetry

We propose the introduction of a Heisenberg symmetry of the Kähler potential to solve the problems with chaotic inflation in supergravity, as a viable alternative to the use of shift symmetry. The slope of the inflaton potential emerges from a small Heisenberg symmetry breaking term in the superpotential. The modulus field of the Heisenberg symmetry is stabilized and made heavy with the help of the large vacuum energy density during inflation. The observable predictions are indistinguishable from those of typical chaotic inflation models, however the form of the inflationary superpotential considered here may be interpreted in terms of sneutrino inflation arising from certain classes of string theory.     

Gravity-induced weak symmetry breaking and supergravity

We give here a review of the recent developments of grand unified theories based onN=1 supergravity. We start with a brief introduction of supersymmetry and supergravity multiplets, and then discuss the construction of an invariant Lagrangian. The phenomena of gravity-induced weak symmetry breaking via the super Higgs effect at the tree level, corresponding to the conventional SU(5) gauge group, are then considered. We then extend this idea to the larger group SO(10), showing two possible breaking chains given as (i) SO(10)×susy→SU(2) _L ×U(1) _R ×U(1) _B-L ×SU(3) _C (≡ G₂₁₁₃)×susy→U(1)_em×SU(3) _C (G _LE ) predicting a secondZ-boson having mass lower than 1 TeV, and (ii) SO(10)×susy→SU(2) _L ×SU(2) _R ×SU(4)→(≡G₂₂₄)×susy→ SU(2) _L ×U(1) _Y ×SU(3) _C (≡ G₂₁₃)×susy→U(1)_em×SU(3) _C . We also consider the radiative breaking of weak symmetry via renormalisation group effects, which predicts the top quark mass. Some experimental signatures of the supersymmetric particles are investigated and possible future outlook is discussed. Invited talk presented at the International Symposium on Theoretical Physics, Bangalore, November 1984.     

B-decay CP-asymmetries in SUSY with a U(2)3 flavour symmetry

We study CP asymmetries in rare B decays within supersymmetry with a U(2)³ flavour symmetry, motivated by the SUSY flavour and CP problems, the hierarchies in the Yukawa couplings and the absence so far of any direct evidence for SUSY. Even in the absence of flavour-blind phases, we find potentially sizable CP violating contributions to b→s decay amplitudes. The effects in the mixing-induced CP asymmetries in B→ϕK _S and B→η′K _S , angular CP asymmetries in B→K ^∗ μ ⁺ μ ⁻ and the direct CP asymmetry in B→X _s γ can be in the region to be probed by LHCb and next generation B factories. At the same time, these effects in B decays are compatible with CP violating contributions to meson mixing, including a non-standard B _s mixing phase hinted by current tensions in the CKM fit mostly between S_yKS, e_KS_{\psi K_{S}}, \epsilon_{K} and DM_Bs/DM_Bd\Delta M_{B_{s}}/\Delta M_{B_{d}}.     

A CP violating mixing matrix compatible with neutral flavour conservation and spontaneous CP violation

A specific ansatz for the Yukawa couplings of a four-generation SU(2)_L×U(1) model with two Higgs doublets is discussed which leads to neutral flavour conservation, spontaneous CP violation and to a genuinely complex mixing matrix. W exchange conserves CP in the limit m_t′ = m_t only. The decay rate for t→b is reduced by factor two compared to the standard model wit three generations. The phenomenological implications for K⁰−K̄⁰ and B⁰−B̄⁰ are investigated.     

Spontaneous CP violation and minimal coupling to supergravity

In the framework of minimal coupling to supergravity, it is found that the assumption of spontaneous CP violation allows one to generate naturally real couplings between the high-energy and the low-energy sectors of the theory, at the grand unification scale M_x. These boundary conditions for the renormalization group equations imply sufficiently small imaginary parts of these couplings at the weak scale M_w, to ensure that the experimental bound on the electric dipole moment of the neutron is respected.     

Spontaneous CP violation in a SUSY model with a complex CKM

It is pointed out that the recent measurement of the angle γ   of the unitarity triangle, providing irrefutable evidence for a complex Cabibbo–Kobayashi–Maskawa (CKM) matrix, presents a great challenge for supersymmetric models with spontaneous CP violation. We construct a new minimal extension of the minimal supersymmetric standard model (MSSM), with spontaneous CP breaking, which leads to a complex CKM matrix, thus conforming to present experimental data. This is achieved through the introduction of two singlet chiral superfields and a vector-like quark chiral superfield which mixes with the standard quarks. A Z₃$Z_3$ symmetry is introduced in order to have a potential solution to the strong CP problem.     

Lepton flavour symmetry and the neutrino magnetic moment

With the standard model gauge group and the three standard left-handed Weyl neutrinos, two minimal scenarios are investigated where an arbitrary non-Abelian lepton flavour symmetry groupG _H is responsible for a light neutrino with a large magnetic moment. In the first case, with scalar fields carrying lepton flavour, some finetuning is necessary to get a small enough neutrino mass for _v =O(10)^–11 _B. In the second scenario, the introduction of heavy charged gauge singlet fermions with lepton flavour allows for a strictly massless neutrino to one-loop order. In both cases, the interference mechanism for smallm and large _v is unique, independently ofG _H . In explicit realizations of the two scenarios, the horizontal groups are found to be non-Abelian extensions of a Zeldovich-Konopinski-Mahmoud lepton number symmetry. Only a discrete part ofG _H is spontaneously broken leading to a light Dirac neutrino with a large magnetic moment.     

CP nonconservation and spontaneous symmetry breaking

The observed CP violation is assumed to be due to the spontaneous symmetry-breaking mechanism; the Lagrangian is CP invariant but its particular solution is not. The general classification of such theories when coupled with different unified gauge models of the weak and electromagnetic interactions is given. All such theories lead naturally to a basically milliweak CP noninvariant solution. The possibility that for most weak transitions the result may resemble a superweak theory is analysed, and possible experiments to distinguish these two different types of theories are discussed. Detailed calculations for various CP violating amplitudes are carried out for a generalized Georgi-Glashow model.     

Chromomagnetism,flavour symmetry breaking and S-wave tetraquarks

The chromomagnetic interaction, with full account for flavour-symmetry breaking, is applied to S-wave configurations containing two quarks and two antiquarks. Phenomenological implications are discussed for light, charmed, charmed and strange, hidden-charm and double-charm mesons, and extended to their analogues with beauty. PACS 12.39.-x; 12.39.Mk; 12.40.Yx     

Four-fermion model with breaking of chiral symmetry and CP parity

A CP-odd, chirally noninvariant four-fermion model with three coupling constants is studied by an effective-potential method. The mass spectrum of the fermion and of the collective scalar and pseudoscalar fields is found. In the particular case of a chirally invariant model, the pseudoscalar field becomes a massless Goldstone field. The complete effective action, which has the form of a -model, is calculated in the single-loop approximation. The Gell-Mann-Levy method is used to find the axial current. Partial conservation of axial current is demonstrated. It is thus shown that the original model reproduces the basic features of non-perturbative quantum chromodynamics: a breaking of chiral symmetry and of CP parity.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 5–10, June, 1989.