55849801
Generalized massive gravity in arbitrary dimensions and its Hamiltonian formulation
We extend the four-dimensional de Rham-Gabadadze-Tolley (dRGT) massive gravity model to a general scalar massive-tensor theory in arbitrary dimensions, coupling a dRGT massive graviton to multiple scalars and allowing for generic kinetic and mass matrix mixing between the massive graviton and the scalars, and derive its Hamiltonian formulation and associated constraint system. When passing to the Hamiltonian formulation, two different sectors arise: a general sector and a special sector. Although obtained via, different ways, there are two second class constraints in either of the two sectors, eliminating the BD ghost. However, for the special sector, there are still ghost instabilities except for the case of two dimensions. In particular, for the special sector with one scalar, there is a "second BD ghost".
119273766
Gravitational waves from oscillon preheating
A bstractOscillons are long-lived, localized excitations of nonlinear scalar fields which may be copiously produced during preheating after inflation, leading to a possible oscillon dominated phase in the early Universe. For example, this can happen after axion monodromy inflation, on which we run our simulations. We investigate the stochastic gravitational wave background associated with an oscillon-dominated phase. An isolated oscillon is spherically symmetric and does not radiate gravitational waves, and we show that the flux of gravitational radiation generated between oscillons is also small. However, a significant stochastic gravitational wave background may be generated during preheating itself (i.e, when oscillons are forming), and in this case the characteristic size of the oscillons is imprinted on the gravitational wave power spectrum, which has multiple, distinct peaks.
119288312
Galileons with Gauge Symmetries
Galileon models arise in certain braneworld scenarios as modifications to General Relativity, and are also interesting as field theories in their own right. We show how the galileon model can be naturally generalized to include local gauge symmetries, by allowing for couplings to Yang-Mills fields. The resulting theories have at most second order spacetime derivatives in any representation of the gauge group, thereby avoiding Ostrogradski ghosts. We also extend the models to include curved space, and show how in that case we need to include non-minimal couplings between the galileons and the curvature tensors for the theory to retain its second order nature.
118686993
Bi-galileon theory II: phenomenology
We continue to introduce bi-galileon theory, the generalisation of the single galileon model introduced by Nicolis et al. The theory contains two coupled scalar fields and is described by a Lagrangian that is invariant under Galilean shifts in those fields. This paper is the second of two, and focuses on the phenomenology of the theory. We are particularly interesting in models that admit solutions that are asymptotically self accelerating or asymptotically self tuning. In contrast to the single galileon theories, we find examples of self accelerating models that are simultaneously free from ghosts, tachyons and tadpoles, able to pass solar system constraints through Vainshtein screening, and do not suffer from problems with superluminality, Cerenkov emission or strong coupling. We also find self tuning models and discuss how Weinberg’s no go theorem is evaded by breaking Poincaré invariance in the scalar sector. Whereas the galileon description is valid all the way down to solar system scales for the self-accelerating models, unfortunately the same cannot be said for self tuning models owing to the scalars backreacting strongly on to the geometry.
55434748
Multi-Galileons, solitons, and Derrick's theorem
The field theory Galilean symmetry, which was introduced in the context of modified gravity, gives a neat way to construct Lorentz-covariant theories of a scalar field, such that the equations of motion contain at most second-order derivatives. Here we extend the analysis to an arbitrary number of scalars, and examine the restrictions imposed by an internal symmetry, focussing in particular on SU(N) and SO(N). This therefore extends the possible gradient terms that may be used to stabilise topological objects such as sigma model lumps.
118418835
Mass-varying massive gravity
It has recently been shown that the graviton can consistently gain a constant mass without introducing the Boulware-Deser ghost. We propose a gravity model where the graviton mass is set by a scalar field and prove that this model is free of the Boulware-Deser ghost by analyzing its constraint system and showing that two constraints arise. We also initiate the study of the model's cosmic background evolution and tentatively discuss possible cosmological implications of this model. In particular, we consider a simple scenario where the scalar field setting the graviton mass is identified with the inflaton and the graviton mass evolves from a high to a low energy scale, giving rise to the current cosmic acceleration.
118442205
Real stabilization method for nuclear single-particle resonances
We develop the real stabilization method within the framework of the relativistic mean-field (RMF) model. With the self-consistent nuclear potentials from the RMF model, the real stabilization method is used to study single-particle resonant states in spherical nuclei. As examples, the energies, widths, and wave functions of low-lying neutron resonant states in {sup 120}Sn are obtained. These results are compared with those from the scattering phase-shift method and the analytic continuation in the coupling constant approach and satisfactory agreements are found.
119268791
GENERALIZED FRIEDBERG-LEE MODEL FOR NEUTRINO MASSES AND LEPTONIC CP VIOLATION FROM μ-τ SYMMETRY BREAKING
Assuming the Majorana nature of massive neutrinos, we generalize the Friedberg-Lee neutrino mass model to include CP violation in the neutrino mass matrix Mν. The most general case with all the free parameters of Mν being complex is discussed. We show that a favorable neutrino mixing pattern (with θ12 ≈ 35.3°, θ23 = 45°, θ13 ≠ 0° and δ = 90°) can naturally be derived from Mν, if it has an approximate or softly-broken μ-τ symmetry. We also point out a different way to obtain the nearly tri-bimaximal neutrino mixing pattern with δ = 0° and non-vanishing Majorana phases.
120532642
Configuration dependence of moments of inertia in the odd-A nucleus from BCS theory
The moments of inertia (Mol) of odd-A and even-even rare-earth nuclei are calculated using the Nilsson + BCS method with and without the blocking effect taken into account. The calculated MoIs with blocking considered is smaller than that without blocking considered. The Mor of an odd-A nucleus depends strongly on which orbital is occupied by the odd nucleon. Although the calculated MoI's are systematically smaller than the data, the large fluctuations in the experimental odd-even differences in MoI's can be reproduced qualitatively. This is contrary to the common assertion that the MoI of an odd-A nucleus is some 15% larger than those of its neighboring even-even nuclei with the BCS theory and is helpful to understand the appearance of normally deformed identical bands in an odd-A nucleus and its even-even neighbors under the mean-field (BCS) approximation.
118456126
Broken S3 flavor symmetry of leptons and quarks: Mass spectra and flavor mixing patterns
Abstract We apply the discrete S 3 flavor symmetry to both lepton and quark sectors of the Standard Model extended by introducing one Higgs triplet and realizing the type-II seesaw mechanism for finite neutrino masses. The resultant mass matrices of charged leptons ( M l ), neutrinos ( M ν ), up-type quarks ( M u ) and down-type quarks ( M d ) have a universal form consisting of two terms: one is proportional to the identity matrix I and the other is proportional to the democracy matrix D . We argue that the textures of M l , M u and M d are dominated by the D term, while that of M ν is dominated by the I term. This hypothesis implies a near mass degeneracy of three neutrinos and can naturally explain why the mass matrices of charged fermions are strongly hierarchical, why the quark mixing matrix is close to I and why the lepton mixing matrix contains two large angles. We discuss a rather simple perturbation ansatz to break the S 3 symmetry and obtain more realistic mass spectra of leptons and quarks as well as their flavor mixing patterns. We stress that the I term, which used to be ignored from M l , M u and M d , is actually important because it can significantly modify the smallest lepton flavor mixing angle θ 13 or three quark flavor mixing angles.
73588936
Lepton Flavor Mixing Pattern and Neutrino Mass Matrix after the Daya Bay Experiment
The Daya Bay Collaboration has recently observed neutrino oscillations in thee → �e disappearance channel, indicating that sin 2 � 13 = 0.024±0.005 (1�) and � 13 = 0 is already excluded at the 5.2� confidence level. Now three neutrino mixing angles have been measured to a good degree of accuracy (�12 ≈ 34 ◦ , �23 ≈ 45 ◦ and �13 ≈ 9 ◦ ). Motivated by these experimental results, we propose a novel lepton flavor mixing pattern, which predicts sin 2 � 23 = 1/2, sin 2 � 12 = (2+ √ 3)/(10+ √ 3) ≈ 0.318 and sin 2 � 13 = (2− √ 3)/12 ≈ 0.022, together with a maximal CP-violating phase � = 90 ◦ . The leptonic CP violation characterized by the Jarlskog invariant J = √ 6/72 ≈ 3.4% is promising to be measured in the future long-baseline neutrino oscillation experiments. Furthermore, we point out that a generalized version of µ-� symmetry may exist in the neutrino sector and can give rise to the aforementioned mixing pattern. The possible realizations in the seesaw models with discrete flavor symmetries are also discussed.