How can we test the neutrino mass seesaw mechanism experimentally?

The seesaw mechanism for the small neutrino mass has been a popular paradigm, yet it has been believed that there is no way to test it experimentally. We present a conceivable outcome from future experiments that would convince us of the seesaw mechanism. It would involve data from the CERN Large Hadron Collider, International Linear Collider, cosmology, underground, and low-energy flavor experiments to establish the case.     

Universal seesaw from left–right and Peccei–Quinn symmetry breaking

To generate the lepton and quark masses in the left–right symmetric models, we can consider a universal seesaw scenario by integrating out heavy fermion singlets which have the Yukawa couplings with the fermion and Higgs doublets. The universal seesaw scenario can also accommodate the leptogenesis with Majorana or Dirac neutrinos. We show that the fermion singlets can obtain their heavy masses from the Peccei–Quinn symmetry breaking.     

Can one have significant deviations from leptonic 3 $$\times $$ 3 unitarity in the framework of type I seesaw mechanism?

We address the question of deviations from \(3\times 3\) unitarity of the leptonic mixing matrix showing that, in the framework of type I seesaw mechanism, one may have significant deviations from unitarity that can be detected at the next round of experiments while some of the heavy neutrino masses are sufficiently low to become within experimental reach. For that purpose we introduce a specially useful parametrisation that enables to control all deviations of unitarity through a single \(3 \times 3\) matrix, which we denote by X and which connects the mixing of the light and heavy neutrinos in the context of type I seesaw. We show that there is no need for the Yukawa couplings to be extremely suppressed. We present specific examples where deviations from \(3\times 3\) unitarity are sufficiently small to conform to all the present stringent experimental bounds.     

The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos

We implement the seesaw mechanism in the 3-3-1 model with right-handed neutrinos. This will be accomplished by the introduction of a scalar sextet into the model and the spontaneous violation of lepton number. The main result of this work is that the seesaw mechanism can work already at the TeV scale with the consequence that the right-handed neutrino masses lie in the electroweak scale, in the range from MeV to tens of GeV. This window provides a great opportunity to test their appearance at current detectors, though when we contrast our results with some previous analyses concerning the detection sensitivity at LHC, we conclude that further work is needed in order to validate this search.     

Same-sign tetralepton signature in type-Ⅱ seesaw at lepton colliders

The same-sign tetralepton signature via the mixing of neutral Higgs bosons and their cascade decays to charged Higgs bosons is a unique signal in the type-Ⅱ seesaw model with the mass spectrum M_A⁰≈M_H⁰>M_H⁺>M_H^±±.In this study,we investigate this signature at future lepton colliders,such as the ILC,CLIC,and MuC.Direct searches for doubly charged scalar H^±±at the LHC have excluded MHg+t<350(870) GeV in the H^±±+W^±W(±)(l^±±)decay mode.Therefore,we choose M_A⁰=400,600,1000,1500 GeV as our benchmark scenarios.Constrained by direct search,H^±±+W^±W(±)(l^±±)d=is the only viable decay mode for Mρ=400 GeV at the √s=1 TeV ILC.With an integrated luminosity L=8 ab^-1,the promising region,with approximately 150 signal events,corresponds to a narrow band in the range of 10^-4 GeV≤v△≤10^-2GeV.Meanwhile,for Mpo=600 GeV at the √s=1.5 TeV CLIC,approximately 10 signal events can be produced with L=2.5 ab^-1.For heavier triplet scalars M_A⁰■870 GeV,although the H^±± decay mode is allowed,the cascade decays are suppressed.A maximum event number~16 can be obtained at approximately v△~4×10⁴GeV and λ₁₄~0.26 for M_A⁰=1000 GeV with L=5 ab^-1 at the √s=3 TeV CLIC.Finally,we find that this signature is not promising for M_A⁰= 1500 GeV at the √s=6 TeV MuC.Based on the benchmark scenarios,we also study the observability of this signature.In the H^±±+W^±W(±)(l^±±)d mode,one can probe MρS 800(1160) GeV at future lepton colliders.     

Confronting the DAMPE excess with the scotogenic type-Ⅱ seesaw model

The DArk Matter Particle Explorer(DAMPE) has observed a tentative peak at E ~ 1.4 Te V in the cosmic-ray electron spectrum.In this paper,we interpret this excess in the scotogenic type-Ⅱ seesaw model.This model extends the canonical type-Ⅱ seesaw model with dark matter(DM) candidates and a loop-induced vacuum expectation value of the triplet scalars,v?,resulting in small neutrino masses naturally even for Te V scale triplet scalars.Assuming a nearby DM subhalo,the DAMPE excess can be explained by DM annihilating into a pair of triplet scalars which subsequently decay to charged lepton final states.Spectrum fitting of the DAMPE excess indicates it potentially favors the inverted neutrino mass hierarchy.We also discuss how to evade associated neutrino flux in our model.     

Which mechanism underlies the water-like anomalies in core-softened potentials?

Using molecular dynamics simulations we investigate the thermodynamics of particles interacting with continuous and discrete versions of a core-softened (CS) intermolecular potential composed by a repulsive shoulder. Dynamical and structural properties are also analyzed by the simulations. We show that in the continuous version of the CS potential the density at constant pressure has a maximum for a certain temperature. Similarly the diffusion constant, D, at a constant temperature has a maximum at a density ρ D _max and a minimum at a density ρ D _min < ρD_max, and structural properties are also anomalous. For the discrete CS potential none of these anomalies are observed. The absence of anomalies in the discrete case and its presence in the continuous CS potential are discussed in the framework of the excess entropy.     

125 GeV Higgs,type III seesaw and gauge–Higgs unification

Recently, both the ATLAS and CMS experiments have observed an excess of events that could be the first evidence for a 125 GeV Higgs boson. This is a few GeV below the (absolute) vacuum stability bound on the Higgs mass in the Standard Model (SM), assuming a Planck mass ultraviolet (UV) cutoff. In this Letter, we study some implications of a 125 GeV Higgs boson for new physics in terms of the vacuum stability bound. We first consider the seesaw extension of the SM and find that in type III seesaw, the vacuum stability bound on the Higgs mass can be as low as 125 GeV for the seesaw scale around a TeV. Next we discuss some alternative new physics models which provide an effective ultraviolet cutoff lower than the Planck mass. An effective cutoff Λ?10¹¹ GeV$\Lambda ?{10}^{11}\text{GeV}$ leads to a vacuum stability bound on the Higgs mass of 125 GeV. In a gauge–Higgs unification scenario with five-dimensional flat spacetime, the so-called gauge–Higgs condition can yield a Higgs mass of 125 GeV, with the compactification scale of the extra-dimension being identified as the cutoff scale Λ?10¹¹ GeV$\Lambda ?{10}^{11}\text{GeV}$. Identifying the compactification scale with the unification scale of the SM SU(2) gauge coupling and the top quark Yukawa coupling yields a Higgs mass of 121±2 GeV$121\pm 2\text{GeV}$.     

Why are large cities faster? Universal scaling and self-similarity in urban organization and dynamics

Cities have existed since the beginning of civilization and have always been intimately connected with humanity's cultural and technological development. Much about the human and social dynamics that takes place is cities is intuitively recognizable across time, space and culture; yet we still do not have a clear cut answer as to why cities exist or to what factors are critical to make them thrive or collapse. Here, we construct an extensive quantitative characterization of the variation of many urban indicators with city size, using large data sets for American, European and Chinese cities. We show that social and economic quantities, characterizing the creation of wealth and new ideas, show increasing returns to population scale, which appear quantitatively as a power law of city size with an exponent β≃ 1.15 > 1. Concurrently, quantities characterizing material infrastructure typically show economies of scale, namely β≃ 0.8 < 1. The existence of pervasive scaling relations across city size suggests a universal social dynamics common to all cities within an urban system. We sketch some of their general ingredients, which include the acceleration of social life and a restructuring of individual social networks as cities grow larger. We also build simple dynamical models to show that increasing returns in wealth and innovation can fuel faster than exponential growth, which inexorably lead to crises of urban organization. To avoid them we show that growth may proceed in cycles, separated by major urban adaptations, with the unintended consequence that the duration of such cycles decreases with larger urban population size and is now estimated to be shorter than a human lifetime.     

Quantum ℛ-Matrices as Universal Qubit Gates

JETP Letters - We study the Chern-Simons approach to the topological quantum computing. We use quantum ℛ-matrices as universal quantum gates and study the approximations of some one-qubit...     

Type I and new seesaw in left–right symmetric theories

We extend the Type I seesaw and suggest a new   seesaw mechanism to generate neutrino masses within the left–right symmetric theories where parity is spontaneously broken. We construct a next to minimal left–right symmetric model where neutrino masses are determined irrespective of the B−L$B-L$ breaking scale and call it the new   seesaw mechanism. In this scenario B−L$B-L$ scale can be very low. This makes B−L$B-L$ gauge boson and the quasi-Dirac heavy leptons very light. These TeV scale particles could have large impact on lepton flavor and CP violating processes. We also shed light on the phenomenological aspects of the model within the reach of the LHC.     

Electrical conduction in native deoxyribonucleic acid: hole hopping transfer mechanism?

Measurements of the quasistatic and frequency dependent electric conductivity below 1 MHz were carried out on wet-spun, macroscopically oriented, calf thymus DNA bulk samples, thus effectively extending previous radio frequency data down to quasistatic time scales. The frequency dependence of the electrical conductivity in the frequency range of approximately 10(-3)-10(15) Hz agrees well with predictions of the hopping hole mechanism. Temperature dependence of the quasistatic electrical conductivity can be rather well described by the activated Arrhenius law with the activation energy of approximately 0.9 eV; however, based on the quality of the fits, the hopping ansatz cannot be ruled out.     

An Underlying Symmetry Determines all Elements of CKM and PMNS up to a Universal Constant?

Observing the CKM matrix elements written in different parametrization schemes,one can notice obvious relations among the sine-values of the CP phases in those schemes.Using the relations,we establish a few parametrizationindependent equations,by which the matrix elements of the CKM matrix can be completely fixed up to a universal parameter.If it is true,we expect that there should exist a hidden symmetry in the nature,which determines the relations.Moreover,it requires a universal parameter,naturally it would be the famous Jarlskog invariant,which is also parametrization independent.Thus the four parameters(three mixing angles and one CP phase) of the CKM matrix are not free,but determined by the symmetry and the universal parameter.As we generalize the rules to the PMNS matrix for neutrino mixing,the CP phase of the lepton sector is predicted to be within a range of 0 ~ 59° centered at39°(in the P_a parametrization) which will be tested in the future experiments.     

Universal Form of Renormalizable Knots in Symbolic Dynamics

The knot structure of three-dimensional flow has been constructed based on minimal braid assumption [Chin.Phys. Lett. 20 (2003)1444]. Here we provide a new universal form of renormalizable knots. From this universal form an arbitrary renormalizable knot can be decomposed into a unique set of elementary templates.     

An Underlying Symmetry Determines all Elements of CKM and PMNS up to a Universal Constant?

Observing the CKM matrix elements written in different parametrization schemes, one can notice obvious relations among the sine-values of the CP phases in those schemes. Using the relations, we establish a few parametrization-independent equations, by which the matrix elements of the CKM matrix can be completely fixed up to a universal parameter. If it is true, we expect that there should exist a hidden symmetry in the nature, which determines the relations. Moreover, it requires a universal parameter, naturally it would be the famous Jarlskog invariant, which is also parametrization independent. Thus the four parameters (three mixing angles and one CP phase) of the CKM matrix are not free, but determined by the symmetry and the universal parameter. As we generalize the rules to the PMNS matrix for neutrino mixing, the CP phase of the lepton sector is predicted to be within a range of 0~59° centered at 39° (in the P_a parametrization) which will be tested in the future experiments.