Academic literature on the topic 'Leptonic mixings'

We study how the elements of the leptonic right-handed mixing matrix can be determined at the LHC in the minimal Left-Right symmetric extension of the standard model. We do it by explicitly relating them with physical quantities of the Keung-Senjanovi\'c process and the lepton number violating decays of the right doubly charged scalar. We also point out that the left and right doubly charged scalars can be distinguished at the LHC, without measuring the polarization of the final state leptons coming from their decays. Then we study time reversal symmetry violation in the $\mu\rightarrow e\gamma $ decay and the $\mu\rightarrow e$ conversion process and compute a T-odd triple vector correlation for the $\mu\rightarrow e\gamma $ decay and the $\mu\rightarrow e$ conversion process, finding simple results in terms of the CP violating phases of the effective Hamiltonians. Finally we focus on the minimal Left-Right symmetric extension of the Standard Model, which is a complete model of neutrino masses that can lead to an appreciable correlation. We show that under rather general assumptions, this correlation can be used to discriminate between Parity or Charge-conjugation as the discrete Left-Right symmetry.

The experimental evidences of neutrino oscillation, caused by non-zero neutrino masses and neutrino mixing, which were obtained in the experiments with solar, atmospheric, accelerator and reactor neutrinos, opened new field of research in elementary particle physics. The principal goal is to understand at fundamental level the mechanism giving rise to non-zero neutrino masses and neutrino mixing. The open fundamental questions include those of the nature — Dirac or Majorana — of massive neutrinos, of the type of spectrum neutrino masses obey, of the status of CP symmetry in the lepton sector, of the absolute scale of neutrino masses, and more generally, of understanding the origin of flavour in particle physics. The smallness of neutrino masses suggests that their values are related to the existence of a new fundamental mass (energy scale) in particle physics, i.e., to New Physics beyond that predicted by the Standard Theory. The New Physics can manifest itself in the Majorana nature of massive neutrinos, in the existence of sterile neutrinos with masses at the eV scale, in the existence of new non-standard interactions (NSI) of neutrinos, etc. The present Ph.D. thesis explores aspects of this neutrino-related New Physics. More specifically, we first employ the discrete flavour symmetry approach i) to construct a self-consistent theory of lepton flavour, ii) to understand the pattern of neutrino mixing and to describe it quantitatively, and iii) to derive predictions for leptonic Dirac CP violation. Next we investigate the effects of existence of sterile neutrinos with a Majorana mass at the eV scale on the predictions for the neutrinoless double beta decay effective Majorana mass. Further we present a possible interpretation of the results of the reactor neutrino and accelerator experiments (Daya Bay, RENO, Double Chooz and T2K) on the reactor angle θ13 in the neutrino mixing matrix in terms of non-standard interactions (NSI) of neutrinos. We also analyse the signatures of sterile neutrinos in reactor antineutrino experiments and, in particular, constrain the active-sterile mixing angle using the high-precision data of the Daya Bay reactor experiment. We finally investigate the impact of sterile neutrinos on precision measurements of the standard neutrino oscillation parameters in the upcoming neutrino experiment JUNO.

We study light hadron phenomenology using Lattice QCD. We focus on the calculations of the light pseudoscalar quantities: masses, decay constants and B-parameters; in particular the calculation of the Kaon B-parameter, BK, which when combined with experimental results yields a constraint of the unitarity triangle apex. We describe a calculation with 2+1 dynamical flavours of Domain Wall Fermions on two lattice volumes, with a lattice spacing a = 0:1 fm. The Iwasaki gauge action was used with coupling beta = 2:13 and the extent of the fifth dimension was Ls = 16. Following a brief review of continuum QCD and Lattice QCD we describe the Domain Wall formalism and the lattice methods used to calculate physical quantities. We present results from the two simulations and make comparisons with next-to-leading order chiral perturbation theory. We study the region of validity of chiral perturbation theory and calculate the associated low energy constants. We find these to agree with phenomenological estimates and other lattice calculations. We calculate the physical decay constants and find them to be in relatively good agreement with experimental values. We present a renormalised value for BK which includes systematic error estimates.

The material is organized as follows: the first chapter is devoted to several remarks on the two basic supersymmetric GUTs - first the minimal SUSY SU(5) is considered and the main shortcomings are pointed-out in brief, and in the second part these issues are addressed concerning a general class of SO(lO) models. This provides a natural motivation to approach and describe shortly the minimal SUSY SO(lO) scheme in the second chapter. The third chapter is dedicated to a detailed study of the correlations among the quark and lepton masses and mixing within the framework with dominant triplet seesaw contribution. An extended framework, a setup with an additional, quasidecoupled Higgs multiplet transforming as 120 of 50(10), is introduced and studied in detail in chapter 4. Chapter 5 is devoted to a class of alternative seesaw schemes emerging in theories with a spinorial 16 in the Higgs sector of SUSY and split-SUSY SO(lO) GUTs. Finally, a set of Appendices is added to coment on technical points in the main text.

Semileptonic B decays of the type Bq⁰→Dq⁻μ⁺ν (where Dq⁻→K⁻K⁺pie⁻) are selected and their lifetimes are corrected using a statistical simulation-based correction called the k-factor. Using 1 fb⁻¹ of LHCb data the B⁰ and Bs⁰ mixing frequencies are measured to be Deltamd = ( 0.503 ± 0.011 (stat) ± 0.013 (syst) ) ps⁻¹ and Deltams = ( 17.93 ± 0.22 (stat) ± 0.15 (syst) ) ps⁻¹. We exclude the null hypothesis of no mixing for the B⁰ and Bs⁰ by 5.8 and 13.0 standard deviations respectively. This is the first observation of Bs Bsbar mixing using only semileptonic B decays. The lepton flavour violating decay D⁰→eμ is searched for, using tagged D⁰ decays from D*→D⁰pie, and the measurement is normalised using D⁰→K⁻pie⁺ decays. No evidence is seen of an excess over the expected background and so a limit is placed B(D⁰→eμ) < 1.3×10⁻⁸ at a 90% confidence level using 3 fb⁻¹ of LHCb data. This improves the previous measurement by a factor of 20 and is the world's best measurement. Possible upgrades to the LHCb VELO detector are simulated and aspects of the upgraded detector are optimised to ensure that all tracks within the angular acceptance can be detected with high precision. Finally the simulated performance of the current and upgraded VELO detectors are compared.

The Standard Model of Elementary Particle Physics (SM) is the present theoryfor the elementary particles and their interactions and is a well-established theorywithin the physics community. The SM is a combination of Quantum Chromodynamics(QCD) and the Glashow{Weinberg{Salam (GWS) electroweak model. QCDis a theory for the strong force, whereas the GWS electroweak model is a theoryfor the weak and electromagnetic forces. This means that the SM describes allfundamental forces in Nature, except for the gravitational force. However, the SMis not a nal theory and some of its problems will be discussed in this thesis.In the rst part of this thesis, several properties of baryons are studied suchas spin structure, spin polarizations, magnetic moments, weak form factors, andnucleon quark sea isospin asymmetries, using the chiral quark model (QM). TheQM is an eective chiral eld theory developed to describe low energy phenomena of baryons, since perturbative QCD is not applicable at low energies. The resultsof the QM are in good agreement with experimental data.The second part of the thesis is devoted to the concept of quantum mechanicalneutrino oscillations. Neutrino oscillations can, however, not occur within the GWSelectroweak model. Thus, this model has to be extended in some way. All studiesincluding neutrino oscillation are done within three avor neutrino oscillationmodels. Both vacuum and matter neutrino oscillations are considered. Especially,global ts to all data of candidates for neutrino oscillations are presented and alsoan analytical formalism for matter enhanced three avor neutrino oscillations usingtime evolution operators is derived. Furthermore, investigations of matter eectswhen neutrinos traverse the Earth are included.The thesis begins with an introductory review of the QM and neutrino oscillationsand ends with the research results, which are given in the nine accompanyingscientic articles.<br>QC 20100616