اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدRadiatively broken symmetries of nonhierarchical neutrinos
88
0
0.0
(
0
)
تأليف
Amol Dighe
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Symmetry-based ideas, such as the quark-lepton complementarity (QLC) principle and the tri-bimaximal mixing (TBM) scheme, have been proposed to explain the observed mixing pattern of neutrinos. We argue that such symmetry relations need to be imposed at a high scale $Lambda sim 10^{12}$ GeV characterizing the large masses of right-handed neutrinos required to implement the seesaw mechanism. For nonhierarchical neutrinos, renormalisation group evolution down to a laboratory energy scale $lambda sim 10^3$ GeV tends to radiatively break these symmetries at a significant level and spoil the mixing pattern predicted by them. However, for Majorana neutrinos, suitable constraints on the extra phases $alpha_{2,3}$ enable the retention of those high scale mixing patterns at laboratory energies. We examine this issue within the Minimal Supersymmetric Standard Model (MSSM) and demonstrate the fact posited above for t
قيم البحث
اقرأ أيضاً
We use an effective-field-theory approach to construct models with naturally light sterile neutrinos, due to either exact or accidental global symmetries. The most attractive models we find are based on gauge symmetries, either discrete or continuous
. We give examples of simple models based on Z_N, U(1), and SU(2).
Effective theories of quantum liquids (superconductors and superfluids of various types) are derived starting from microscopic models at the absolute zero of temperature. Special care is taken to assure Galilei invariance. The effective theories are
employed to investigate the quantum numbers carried by the topological defects present in the phases with spontaneously broken symmetries. Due to topological terms induced by quantum fluctuations, these numbers are sometimes found to be fractional. The zero-temperature effective theories are further used to study the quantum critical behavior of the liquid-to-insulator transition which these systems undergo as the applied magnetic field, the amount of impurities, or the charge carrier density varies. The classical, finite-temperature phase transitions to the normal state are discussed from the point of view of dual theories, where the defects of the original formulation become the elementary excitations. A connection with bosonization is pointed out.
We consider holographic theories at finite temperature in which a continuous global symmetry in the bulk is spontaneously broken. We study the linear response of operators in a regime which is dual to time dependent, long wavelength deformations of s
olutions generated by the symmetry. By computing the boundary theory retarded Greens function we show the existence of a gapless mode with a diffusive dispersion relation. The diffusive character of the mode is compatible with the absence of a conserved charge from the field theory point of view. We give an analytic expression for the corresponding diffusion constant in terms of thermodynamic data and a new transport coefficient $sigma_{b}$ which is fixed by the black hole horizon data. After adding a perturbative source on the boundary, we compute the resulting gap $deltaomega_{g}$ as a simple function of $sigma_{b}$ and of data of the thermal state.
To resolve the nature of the hidden order below 17.5,K in the heavy fermion compound URu$_2$Si$_2$, identifying which symmetries are broken below the hidden order transition is one of the most important steps. Several recent experiments on the electr
onic structure have shown that the Fermi surface in the hidden order phase is quite close to the result of band-structure calculations within the framework of itinerant electron picture assuming the antiferromagnetism. This provides strong evidence for the band folding along the c-axis with the ordering vector of $(0,0,1)$, corresponding to broken translational symmetry. In addition to this, there is growing evidence for fourfold rotational symmetry breaking in the hidden-order phase from measurements of the in-plane magnetic anisotropy and the effective mass anisotropy in the electronic structure, as well as the orthorhombic lattice distortion. This broken fourfold symmetry gives a stringent constraint that the symmetry of the hidden order parameter should belong to the degenerate $E$-type irreducible representation. We also discuss a possibility that time reversal symmetry is also broken, which further narrows down the order parameter that characterizes the hidden order.
We demonstrate how residual flavour symmetries, infrared signatures of symmetry breaking in complete models of flavour, can naturally forbid (or limit in a flavour specific way) flavour-changing neutral currents (FCNC) in multi-Higgs-doublet models (
MHDM) without using mass hierarchies. We first review how this model-independent mechanism can control the fermionic mixing patterns of the Standard Model, and then implement the symmetries in the Yukawa sector of MHDM, which allows us to intimately connect the predictivity of a given flavour model with its ability to sequester FCNC. Finally, after discussing various subtleties of the approach, we sketch an $A_4$ toy model that realises an explicit example of these simplified constructions.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
