Search results for "Explicit symmetry breaking"
showing 9 items of 19 documents
Clockwork Goldstone Bosons
2017
The clockwork mechanism has recently been proposed as a natural way to generate hierarchies among parameters in quantum field theories. The mechanism is characterized by a very specific pattern of spontaneous and explicit symmetry breaking, and the presence of new light states referred to as `gears'. In this paper we begin by investigating the self-interactions of these gears in a scalar clockwork model and find a parity-like selection rule at all orders in the fields. We then proceed to investigate how the clockwork mechanism can be realized in 5D linear dilaton models from the spontaneous symmetry breaking of a complex bulk scalar field. We also discuss how the clockwork mechanism is mani…
Dynamical Symmetry Breaking in Warped Compactifications
2001
We study dynamical electroweak symmetry breaking in the Randall-Sundrum scenario. We show that one extra dimension is enough to give the correct pattern of electroweak symmetry breaking in a simple model with gauge bosons and the right-handed top quark in the bulk. The top quark mass is also in agreement with experiment. Furthermore, we propose an extended scenario with all Standard Model gauge bosons and fermions propagating in the bulk, which naturally accommodates the fermion mass hierarchies. No new fields or interactions beyond the observed in the Standard Model are required.
Dynamical left-right symmetry breaking.
1995
We study a left--right symmetric model which contains only elementary gauge boson and fermion fields and no scalars. The phenomenologically required symmetry breaking emerges dynamically leading to a composite Higgs sector with a renormalizable effective Lagrangian. We discuss the pattern of symmetry breaking and phenomenological consequences of this scenario. It is shown that a viable top quark mass can be achieved for the ratio of the VEVs of the bi--doublet $\tan\beta\equiv\kappa/\kappa'$ =~ 1.3--4. For a theoretically plausible choice of the parameters the right--handed scale can be as low as $\sim 20 TeV$; in this case one expects several intermediate and low--scale scalars in addition…
Composite states of two right-handed neutrinos
2016
In this work, we develop a model for Higgs-like composites based on two generations of right-handed neutrinos that condense. We analyze the spontaneous symmetry breaking of the theory with two explicit breakings, setting the different scales of the model and obtaining massive bosons as a result. Finally, we calculate the gravitational wave imprint left by the phase transition associated with the symmetry breaking of a generic potential dictated by the symmetries of the composites.
Noncritically squeezed light via spontaneous rotational symmetry breaking.
2007
We theoretically address squeezed light generation through the spontaneous breaking of the rotational invariance occuring in a type I degenerate optical parametric oscillator (DOPO) pumped above threshold. We show that a DOPO with spherical mirrors, in which the signal and idler fields correspond to first order Laguerre-Gauss modes, produces a perfectly squeezed vacuum with the shape of a Hermite-Gauss mode, within the linearized theory. This occurs at any pumping level above threshold, hence the phenomenon is non-critical. Imperfections of the rotational symmetry, due e.g. to cavity anisotropy, are shown to have a small impact, hence the result is not singular.
Symmetry of molecular properties
1993
The symmetry of coefficients in the expansion of a given molecular property are shown to be obtainable through well defined tensor methods. The analytical expansions required of various vibrational and rotational tensors are given up to the fourth degree in dynamical variables. To illustrate the method, some rovibrational properties of spherical tops are considered. The symmetry of the associated molecular constants is expressed, simultaneously, for XY4 and XY6 molecules, by algebraic relations involving the independent constants and the coupling symbols of the molecular symmetry group. To allow comparisons, some examples are given for which the symmetry of the constants has been published …
Neutral pion production at threshold and low-energy theorems
1990
Abstract Recent experiments of neutral pion photoproduction show a strong discrepancy between experimental data and the predictions of low-energy theorems (LET). The basic ingredients of these theorems are the conservation of the electromagnetic current and the hypothesis of a partially conserved axial current (PCAC). Both, anomalies in the t-channel, and rescattering in a simple R-matrix formalism, lead to small corrections of the order of 10 – 20 %. However, the investigation of the effects of chiral symmetry breaking and isospin symmetry breaking at the quark level in a current algebraic approach leads to substantial contributions of the right order of magnitude.
S3 symmetry and the quark mixing matrix
2016
We impose an $S_3$ symmetry on the quark fields under which two of three quarks transform like a doublet and the remaining one as singlet, and use a scalar sector with the same structure of $SU(2)$ doublets. After gauge symmetry breaking, a $\mathbb{Z}_2$ subgroup of the $S_3$ remains unbroken. We show that this unbroken subgroup can explain the approximate block structure of the CKM matrix. By allowing soft breaking of the $S_3$ symmetry in the scalar sector, we show that one can generate the small elements, of quadratic or higher order in the Wolfenstein parametrization of the CKM matrix. We also predict the existence of exotic new scalars, with unconventional decay properties, which can …
S-4 as a natural flavor symmetry for lepton mixing
2008
Group theoretical arguments seem to indicate the discrete symmetry S4 as the minimal flavour symmetry compatible with tribimaximal neutrino mixing. We prove in a model independent way that indeed S4 can realize exact tribimaximal mixing through different symmetry breaking patterns. We present two models in which lepton tribimaximal mixing is realized in different ways and for each one we discuss the superpotential that leads to the correct breaking of the flavor symmetry.