Composite Leptons at the LHC

In some models of electro-weak interactions the W and Z bosons are considered composites, made up of spin-one-half subconstituents. In these models a spin zero counterpart of the W and Z boson naturally appears, whose higher mass can be attributed to a particular type of hyperfine spin interaction among the various subconstituents. Recently it has been argued that the scalar state could be identified with the newly discovered Higgs (H) candidate. Here we use the known spin splitting between the W/Z and H states to infer, within the framework of a purely phenomenological model, the relative strength of the spin-spin interactions. The results are then applied to the lepton sector, and used to crudely estimate the relevant spin splitting between the two lowest states. Our calculations in many ways parallels what is done in the SU(6) quark model, where most of the spin splittings between the lowest lying baryon and meson states are reasonably well accounted for by a simple color hyperfine interaction, with constituent (color-dressed) quark masses.Comment: 12 pages, footnotes added. Conforms to published versio

Inconsistencies from a Running Cosmological Constant

We examine the general issue of whether a scale dependent cosmological constant can be consistent with general covariance, a problem that arises naturally in the treatment of quantum gravitation where coupling constants generally run as a consequence of renormalization group effects. The issue is approached from several points of view, which include the manifestly covariant functional integral formulation, covariant continuum perturbation theory about two dimensions, the lattice formulation of gravity, and the non-local effective action and effective field equation methods. In all cases we find that the cosmological constant cannot run with scale, unless general covariance is explicitly broken by the regularization procedure. Our results are expected to have some bearing on current quantum gravity calculations, but more generally should apply to phenomenological approaches to the cosmological vacuum energy problem.Comment: 34 pages. Typos fixed, references added, one section expande

Wheeler-DeWitt Equation in 3 + 1 Dimensions

Physical properties of the quantum gravitational vacuum state are explored by solving a lattice version of the Wheeler-DeWitt equation. The constraint of diffeomorphism invariance is strong enough to uniquely determine the structure of the vacuum wave functional in the limit of infinitely fine triangulations of the three-sphere. In the large fluctuation regime the nature of the wave function solution is such that a physically acceptable ground state emerges, with a finite non-perturbative correlation length naturally cutting off any infrared divergences. The location of the critical point in Newton's constant $G_c$, separating the weak from the strong coupling phase, is obtained, and it is inferred from the structure of the wave functional that fluctuations in the curvatures become unbounded at this point. Investigations of the vacuum wave functional further suggest that for weak enough coupling, $G<G_c$, a pathological ground state with no continuum limit appears, where configurations with small curvature have vanishingly small probability. One is then lead to the conclusion that the weak coupling, perturbative ground state of quantum gravity is non-perturbatively unstable, and that gravitational screening cannot be physically realized in the lattice theory. The results we find are in general agreement with the Euclidean lattice gravity results, and lend further support to the claim that the Lorentzian and Euclidean lattice formulations for gravity describe the same underlying non-perturbative physics.Comment: 44 pages, 5 figures. arXiv admin note: text overlap with arXiv:1207.375

Cosmological Density Perturbations with a Scale-Dependent Newton's G

We explore possible cosmological consequences of a running Newton's constant $G ( \Box )$, as suggested by the non-trivial ultraviolet fixed point scenario in the quantum field-theoretic treatment of Einstein gravity with a cosmological constant term. In particular we focus here on what possible effects the scale-dependent coupling might have on large scale cosmological density perturbations. Starting from a set of manifestly covariant effective field equations derived earlier, we systematically develop the linear theory of density perturbations for a non-relativistic, pressure-less fluid. The result is a modified equation for the matter density contrast, which can be solved and thus provides an estimate for the growth index parameter $\gamma$ in the presence of a running $G$. We complete our analysis by comparing the fully relativistic treatment with the corresponding results for the non-relativistic (Newtonian) case, the latter also with a weakly scale dependent $G$.Comment: 54 pages, 4 figure

Holographic Dark Energy Like in f(R)f(R) Gravity

We investigate the corresponding relation between $f(R)$ gravity and holographic dark energy. We introduce a kind of energy density from $f(R)$ which has role of the same as holographic dark energy. We obtain the differential equation that specify the evolution of the introduced energy density parameter based on varying gravitational constant. We find out a relation for the equation of state parameter to low redshifts which containing varying $G$ correction.Comment: 10 page

Soliton excitations in halogen-bridged mixed-valence binuclear metal complexes

Motivated by recent stimulative observations in halogen (X)-bridged binuclear transition-metal (M) complexes, which are referred to as MMX chains, we study solitons in a one-dimensional three-quarter-filled charge-density-wave system with both intrasite and intersite electron-lattice couplings. Two distinct ground states of MMX chains are reproduced and the soliton excitations on them are compared. In the weak-coupling region, all the solitons are degenerate to each other and are uniquely scaled by the band gap, whereas in the strong-coupling region, they behave differently deviating from the scenario in the continuum limit. The soliton masses are calculated and compared with those for conventional mononuclear MX chains.Comment: 9 pages, 10 figures embedded, to be published in J. Phys. Soc. Jpn. 71, No. 1 (2002

Wheeler-DeWitt Equation in 2 + 1 Dimensions

The infrared structure of quantum gravity is explored by solving a lattice version of the Wheeler-DeWitt equations. In the present paper only the case of 2+1 dimensions is considered. The nature of the wavefunction solutions is such that a finite correlation length emerges and naturally cuts off any infrared divergences. Properties of the lattice vacuum are consistent with the existence of an ultraviolet fixed point in $G$ located at the origin, thus precluding the existence of a weak coupling perturbative phase. The correlation length exponent is determined exactly and found to be $\nu=6/11$. The results obtained so far lend support to the claim that the Lorentzian and Euclidean formulations belong to the same field-theoretic universality class.Comment: 56 pages, 7 figures, typos fixed, references adde

How different genders use profanity on Twitter?

Social media, is often the go-to place where people discuss their opinions and share their feelings. As some platforms provide more anonymity than others, users have taken advantage of that privilege, by sitting behind the screen, the use of profanity has been able to create a toxic environment. Although not all profanities are used to offend people, it is undeniable that the anonymity has allowed social media users to express themselves more freely, increasing the likelihood of swearing. In this study, the use of profanity by different gender classes is compiled, and the findings showed that different genders often employ swear words from different hate categories, e.g. males tend to use more terms from the “disability” hate group. Classification models have been developed to predict the gender of tweet authors, and results showed that profanity could be used to uncover the gender of anonymous users. This shows the possibility that profiling of cyberbullies can be done from the aspect of gender based on profanity usage

Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures

Transient creep occurs during geodynamic processes that impose stress changes on rocks at high temperatures. The transient is manifested as evolution in the viscosity of the rocks until steady-state flow is achieved. Although several phenomenological models of transient creep in rocks have been proposed, the dominant microphysical processes that control such behavior remain poorly constrained. To identify the intragranular processes that contribute to transient creep of olivine, we performed stress-reduction tests on single crystals of olivine at temperatures of 1250–1300°C. In these experiments, samples undergo time‐dependent reverse strain after the stress reduction. The magnitude of reverse strain is ~10-3 and increases with increasing magnitude of the stress reduction. High-angular resolution electron backscatter diffraction analyses of deformed material reveal lattice curvature and heterogeneous stresses associated with the dominant slip system. The mechanical and microstructural data are consistent with transient creep of the single crystals arising from accumulation and release of backstresses among dislocations. These results allow the dislocation‐glide component of creep at high temperatures to be isolated, and we use these data to calibrate a flow law for olivine to describe the glide component of creep over a wide temperature range. We argue that this flow law can be used to estimate both transient creep and steady‐state viscosities of olivine, with the transient evolution controlled by the evolution of the backstress. This model is able to predict variability in the style of transient (normal versus inverse) and the load-relaxation response observed in previous work.LH and DW acknowledge support from the Natural Environment Research Council, grant NE/M000966/1, LH and CT acknowledge support from the Natural Environment Research Council, grant 1710DG008/JC4, and DW acknowledges support from the Netherlands Organisation for Scientific Research, User Support Programme Space Research, grant ALWGO.2018.038, and startup funds from Utrecht University. LH recognizes funds used to develop the uniaxial apparatus from the John Fell Fund at the University of Oxford