Hierarchical Mass Research Articles

Fermion mass hierarchy in modular flavor symmetry

The modular flavor symmetry is studied to explain the mass hierarchy of quarks and leptons. In this review, at first, we introduce briefly the framework of the modular symmetries and its residual symmetries, and then, present the general framework of generating the mass hierarchy close to the symmetric points of modulus without fine-tuning. Finally, we present a minimal [Formula: see text] modular invariant model of quarks. We then describe how to obtain the hierarchical quark mass patterns in the vicinity of [Formula: see text] and investigate the flavor structure of the quark mass matrices. The results of our study show that describing correctly the quark mass hierarchies without severe fine-tuning and the CP violation is remarkably challenging within the modular invariance approach to flavors.

Proton Decay and Gauge Coupling Unification in an Extended SU(5) GUT with 45D Higgs

Abstract We present a comprehensive study of an extended SU(5) grand unified theory (GUT) that incorporates a 45D Higgs representation to address the shortcomings of the minimal SU(5) GUT, such as the inability to generate realistic fermion mass hierarchies and insufficient proton stability. By considering a hierarchical mass spectrum for the scalar components of the 45D Higgs, we demonstrate that successful gauge coupling unification (GCU) can be achieved. The color octet scalar, color triplet scalar, and color antitriplet scalar play crucial roles in realizing GCU when their masses are significantly lighter than other components of the 45D Higgs. We focus on the proton decay channels mediated by the exchange of the color antitriplet scalar. Assuming that the 45D Higgs couples to all three generations of fermions, we determine the 45D Higgs Yukawa couplings with which the observed fermion mass matrices at low energies are realized. We calculate proton decay rates using the Yukawa couplings obtained from renormalization group evolutions and matching conditions at the GUT scale, thereby exploring the dependence of proton decay rates on model parameters. We find that the $p \rightarrow \nu \pi$ mode imposes the most stringent constraint on the mass of the color antitriplet scalar $M_{S_1}$. We also study the correlations between the lower bounds on $M_{S_1}$ derived from different proton decay modes.

Efficient energy absorption of bio-inspired bi-directional gradient hierarchical multi-cell structure

This research proposes a novel bio-inspired bi-directional gradient hierarchical multi-cell (BGHM) structure for efficient energy absorption. Its dynamic crushing performance and energy absorption behaviours are comprehensively investigated through numerical simulations and theoretical analysis. Extensive numerical simulations are conducted on the proposed BGHM structure with varying hierarchical orders and masses. The obtained results demonstrate that the specific energy absorption of the third-order BGHM tube is significantly improved, exhibiting a 110% increase compared to the zero-order BGHM tube. Additionally, the undulation of the loading resistance of the third-order BGHM tube decreased by up to 93.0% when compared to a conventional square tube, highlighting the tremendous potential of BGHM tubes for the development of highly effective energy absorbers. In addition, a new trigger mechanism using the pre-crushing method can eliminate the initial peak crushing force of the BGHM, demonstrating the promising potential of triggers in optimizing the crashworthiness of energy absorbers. Furthermore, a comparative analysis reveals that the specific energy absorption of the BGHM outperforms other existing hierarchical multi-cell square tubes in literature. This underscores the superior energy absorption capabilities of the proposed BGHM. To complement the numerical findings, a theoretical study on the proposed BGHM's mean crushing force is carried out. The results from this theoretical study show excellent agreement with the numerical results and further validate the efficacy of the proposed design. The findings indicate that the bio-inspired bi-directional gradient hierarchy incorporated in the BGHM structure offers promising prospects for advancements in energy absorption technology across various industries.

Search for new physics in semileptonic decays of K and B as implied by the g−2 anomaly in FSM

The framed standard model (FSM), constructed to explain, with some success, why there should be three and apparently only three generations of quarks and leptons in nature falling into a hierarchical mass and mixing pattern, 10 suggests also, among other things, a scalar boson U, with mass around 17 MeV and small couplings to quarks and leptons, 11 which might explain 9 the [Formula: see text] anomaly reported in experiment. 12 The U arises in FSM initially as a state in the predicted “hidden sector” with mass around 17[Formula: see text]MeV, which mixes with the standard model (SM) Higgs [Formula: see text], acquiring thereby a coupling to quarks and leptons and a mass just below 17[Formula: see text]MeV. The initial purpose of this paper is to check whether this proposal is compatible with experiment on semileptonic decays of Ks and Bs where the U can also appear. The answer to this we find is affirmative, in that the contribution of U to new physics as calculated in the FSM remains within the experimental bounds, but only if [Formula: see text] lies within a narrow range just below the unmixed mass. As a result from this, one has an estimate [Formula: see text]–17[Formula: see text]MeV for the mass of U, and from some further considerations the estimate [Formula: see text][Formula: see text]eV for its width, both of which may be useful for an eventual search for it in experiment. If found, it will be, for the FSM, not just the discovery of a predicted new particle, but the opening of a window into a whole “hidden sector” containing at least some, perhaps even the bulk, of the dark matter in the universe.

Enabling efficient ample-level oxygen evolution on nickel-iron Prussian blue analogue/hydroxide via hierarchical mass transfer channel construction

Enhancing double-phase mass transfer capability and reducing overpotential at high currents are critical in the oxygen evolution reaction (OER) catalyst design. In this work, nickel–iron layered double hydroxide (NiFe-LDH) loaded on nickel foam (NF) was used as a self-sacrificing template for subsequent growth of nickel–iron Prussian blue (NiFe-PBA) hollow nanocubes on its sheet arrays. The triple-scale porous structure is therefore in-situ constructed in the produced NiFe-PBA@LDH/NF catalyst, where NiFe-PBA nanocubes, NiFe-LDH sheets and NF skeletons provide pores at hundred-nanometers, microns and hundred-microns, respectively. Due to the successful construction of hierarchical mass transfer channels in the catalyst, the overpotential required to deliver 1000 mA cm−2 OER is only 396 mV, which is 80 mV lower than that of NiFe-LDH/NF with a double-scale porous structure, manifesting the importance of the appropriate mass transfer channels, promoting the potential application of the NiFe-PBA@LDH/NF catalyst in industrial-scale electrolysers.

The proto-galaxy of Milky Way-mass haloes in the FIRE simulations

ABSTRACT Observational studies are finding stars believed to be relics of the earliest stages of hierarchical mass assembly of the Milky Way (i.e. proto-galaxy). In this work, we contextualize these findings by studying the masses, ages, spatial distributions, morphology, kinematics, and chemical compositions of proto-galaxy populations from the 13 Milky Way (MW)-mass galaxies from the FIRE-2 cosmological zoom-in simulations. Our findings indicate that proto-Milky Way populations: (i) can have a stellar mass range between 1 × 108 < M⋆ < 2 × 1010 [M⊙], a virial mass range between 3 × 1010 < M⋆ < 6 × 1011 [M⊙], and be as young as 8 ≲ Age ≲ 12.8 [Gyr] (1 ≲ z ≲ 6); (ii) are pre-dominantly centrally concentrated, with $\sim 50~{{\ \rm per\ cent}}$ of the stars contained within 5–10 kpc; (iii) on average show weak but systematic net rotation in the plane of the host’s disc at z = 0 (i.e. 0.25 ≲ 〈κ/κdisc〉 ≲ 0.8); (iv) present [α/Fe]-[Fe/H] compositions that overlap with the metal-poor tail of the host’s old disc; and (v) tend to assemble slightly earlier in Local Group-like environments than in systems in isolation. Interestingly, we find that $\sim 60~{{\ \rm per\ cent}}$ of the proto-Milky Way galaxies are comprised by 1 dominant system (1/5 ≲M⋆/M⋆, proto-MilkyWay≲ 4/5) and 4–5 lower mass systems (M⋆/M⋆, proto-MilkyWay≲ 1/10); the other $\sim 40~{{\ \rm per\ cent}}$ are comprised by 2 dominant systems and 3–4 lower mass systems. These massive/dominant proto-Milky Way fragments can be distinguished from the lower mass ones in chemical-kinematic samples, but appear (qualitatively) indistinguishable from one another. Our results could help observational studies disentangle if the Milky Way formed from one or two dominant systems.

Monogenetic volcanoes as windows into transcrustal mush: A case study of Slamet and Loyang volcanoes, Central Java

Monogenetic volcanic fields (MVFs) are commonly associated with long-lived polygenetic composite volcanoes in many tectonic settings. The association between polygenetic and monogenetic volcanoes has raised questions as to the source of melts feeding monogenetic volcanoes – specifically, whether they are derived from the transcrustal mush underlying a nearby polygenetic volcano, or from a batch of parental magma derived from a different mantle source. To address this question, we studied a well-constrained suite of scoria samples from Gunung Slamet in Central Java, Indonesia, and its most distal monogenetic scoria cone, Gunung Loyang. Slamet is composed of calc-alkaline basalts, and has an extensive MVF on its eastern flank, similar to other Indonesian volcanoes. We analyzed the textural and chemical features of the olivine cargo in both volcanoes, including olivine- and clinopyroxene-hosted melt inclusions. These melt inclusions are the first such analyzed for volatile element contents (H2O, CO2) in the Slamet-Loyang system. We applied hierarchical clustering and mass balance models to constrain the features of the olivine populations in both systems. The olivines in both volcanoes cluster in five distinct textural groups, defined by the presence or lack of zoning and resorption, and according to the type and degree of zoning they exhibit. Olivines show a range of moderate to evolved Fo%, and they also show significant variation in nickel contents (50–1600 ppm). By estimating saturation pressures of entrapped melt inclusions, we observe that Loyang olivines are drawn from a similar petrological system as Slamet, but from deeper mid-crustal levels (12 km), and more mafic source. Our work suggests that monogenetic volcanoes like Loyang can be used as “petrological windows” into the deeper crustal levels of mush reservoirs at composite stratovolcanoes and their associated MVFs.

SN1987A and neutrino non-radiative decay

We investigate neutrino non-radiative two-body decay in vacuum, in relation to SN1987A. In a full 3ν decay framework, we perform a detailed likelihood analysis of the 24 neutrino events from SN1987A observed by Kamiokande-II, IMB, and Baksan. We consider both normal and inverted neutrino mass orderings, and the possibility of strongly hierarchical and quasi-degenerate neutrino mass patterns. The results of the likelihood analysis show that the sensitivity is too low to derive bounds in the case of normal mass ordering. On the contrary, in the case of inverted mass ordering we obtain the bound τ/m≥2.4×105 s/eV (1.2×105) s/eV at 68% (90%) CL on the lifetime-to-mass ratio of the mass eigenstates ν2 and ν1.

Multi-brane cosmology

5D warped extra dimension models with multiple 3-branes can naturally realize multiple hierarchical mass scales which are ubiquitous in physics beyond the Standard Model. We discuss cosmological consequences of such multi-brane models with stabilized radions. It is confirmed that for temperatures below the scale of the IR brane at the end of the extra dimension, we recover the ordinary expansion of the Universe, with the Hubble expansion rate determined by sum of the physical energy densities on all 3-branes where they are localized. In addition, we explore the cosmology for temperatures above the scales of the intermediate and IR branes where the Universe is described by a spacetime with the 3-branes replaced by an event horizon. As the temperature of the Universe cools down, phase transitions are expected to take place, and the intermediate and IR branes come out from behind the event horizon. The Goldberger-Wise mechanism for radion stabilization has a well-known problem of having a supercooled phase transition, which typically does not get completed in time. This problem is even more severe when an intermediate brane is introduced, whose scale is well above TeV, as the corresponding Hubble rate is much larger. We circumvent the problem by employing an alternative mechanism for radion stabilization with dark Yang-Mills fields, which prevents a long supercooling epoch, but still allows the strong first order phase transitions. As a result, the phase transitions in our multi-brane Universe predict a stochastic gravitational wave background with a unique multi-peak signature, which is within the sensitivity reach of future space-based gravitational wave observers. We also show that there are N − 1 radions for an N 3-brane set-up, unlike a recent claim that there exists only one radion.

Exploring the vacuum structure of gravitationally induced neutrino masses

In this work, we explore the proposed mechanism in which the gravitational $\ensuremath{\theta}$ anomaly generates neutrino masses. We highlight that the leading renormalizable interactions of the neutrino condensate forbid the possibility of generating hierarchical masses consistent with observation. This conclusion still holds when Standard Model loop corrections are accounted for. We show that higher-dimensional operators can alleviate this problem. The higher-dimensional operators could be generated from the gravitational anomaly itself, but there is no clear way to know without a deeper understanding of the low-energy description of this mechanism. Because of that, we explore the possibility of new particles generating neutrino mass splittings. We show that both new particles that alter the scalar potential of the condensate or new particles in loops for the neutrino self-energy can solve this problem.

Generation of neutrino dark matter, baryon asymmetry, and radiation after quintessential inflation

We construct a model explaining dark matter, baryon asymmetry, and reheating in a quintessential inflation model. Three generations of right-handed neutrinos having hierarchical masses and the light scalar field leading to the self-interaction of active neutrinos are introduced. The lightest sterile neutrino is a dark matter candidate produced by a Dodelson-Widrow mechanism in the presence of a new light scalar field, while the heaviest and next-heaviest sterile neutrinos produced by gravitational particle production are responsible for the generation of the baryon asymmetry. Reheating is realized by spinodal instabilities of the Standard Model Higgs field induced by the nonminimal coupling to the scalar curvature, which can solve the overproduction of gravitons and curvature perturbation created by the Higgs condensation.

Minimal Nambu-Goldstone-Higgs model in supersymmetric SU(5) revisited

We revisit the minimal Nambu-Goldstone (NG) Higgs supersymmetric (SUSY) SU(5) grand unified model and study its phenomenological implications. The Higgs sector of the model possesses a global SU(6) symmetry, which is spontaneously broken and results in the Higgs doublets of the minimal SUSY Standard Model (MSSM) as NG chiral superfields. Therefore, the model naturally leads to light Higgs doublets and solves the doublet-triplet splitting problem. Because of the SU(6) symmetry, the couplings of the Higgs sector are tightly restricted, and thus the model is more predictive than the minimal SUSY SU(5). We determine all the grand-unified-theory parameters via the matching conditions of the gauge coupling constants at the unification scale and calculate proton lifetime, confronting this with current experimental bounds. We discuss that this model is incompatible with the constrained MSSM, whilst it has a large viable parameter space in the high-scale SUSY scenario. The perturbativity condition on the trilinear coupling of the adjoint Higgs field imposes an upper (lower) limit on the wino (gluino) mass, implying a hierarchical mass pattern for these gauginos. Future proton-decay searches can probe a large part of the parameter space, especially if the SUSY-breaking scale is $\lesssim 100$~TeV.

One-step growth of the interconnected carbon nanotubes/graphene hybrids from cuttlebone-derived bi-functional catalyst for lithium-ion batteries

Carbon nanotubes/graphene hybrid materials with excellent physicochemical properties can be widely applied in the fields of energy storage, electrocatalysis, sensing, etc. Reducing the self-stacking and achieving covalent interaction between carbon nanotubes and graphene are important to ensure a stable hierarchical architecture and effective mass transfer. Herein, we propose a one-step strategy to synthesize 3D interconnected carbon nanotubes/graphene hybrids on the easy-to-remove biomass-derived substrate. The calcined natural cuttlebone as bi-functional catalyst precursor can simultaneously grow carbon nanotubes and graphene by one-step chemical vapor deposition without the addition of extra metal catalysts, while the interconnected structure can act as the porous template for graphene growth. The simultaneous growth process can obtain covalent bonding between carbon nanotubes and graphene, while the crystalline quality and interlayer space can be adjusted by different carbon sources and growth parameters (e.g., temperature). The one-step grown carbon nanotubes/graphene hybrids with seamless interfaces and hierarchical interconnected 3D structure can effectively enhance the electron transfer as well as the electrolyte infiltration efficiency. When utilized as lithium-ion batteries (LIBs) anode, a high specific capacity (544 mAh g–1 at 0.1 A g–1), good rate capability (200 mAh g–1 at 6.4 A g–1 with an ultrashort charge time of 113 s), and excellent cyclic stability can be achieved. This simple and one-step carbon nanotubes/graphene hybrids fabrication strategy can be easily scale-up and applied in various fields.

Effects of Variations of SUSY Breaking Scale on Neutrino Parameters at Low Energy Scale under Radiative Corrections

The paper addresses the effects of the variations of the SUSY breaking scale m s in the range (2-14) TeV on the three neutrino masses and mixings, in running the renormalization group equations (RGEs) for different input values of high energy seesaw scale M R , and in both normal and inverted hierarchical neutrino mass models. The present investigation is a continuation of the earlier works based on the variation of m s scale. Two approaches are adopted one after another—bottom-up approach for running gauge and Yukawa couplings from low to high energy scale, followed by the top-down approach from high to low energy scale for running neutrino parameters defined at high energy scale, along with gauge and Yukawa couplings. A self-complementarity relation among three mixing angles is also employed in the analysis and it is found to be stable under radiative correction. Significant effect due to radiative corrections on neutrino parameters with the variation of SUSY breaking scale m s is observed. For comparison of the results, variation of tan β for different M R is also considered.

A split seesaw model with hidden neutrinoless double beta decay but successful leptogenesis

In a paper by Asaka, Ishida and Tanaka (Phys. Rev. D 103:015014, 2021), they proposed a novel possibility (which will be referred to as the AIT ansatz) that, in spite of the Majorana nature of neutrinos, the neutrinoless double beta (0nu beta beta ) decay can be hidden. In the original AIT model, the AIT ansatz is realized in the minimal seesaw model with two right-handed neutrinos which have a hierarchical mass structure: the lighter and heavier right-handed neutrinos are respectively much lighter and heavier than the typical Fermi-momentum scale of nuclei. However, the original AIT model does not accommodate a successful leptogenesis. For this problem, in this paper we study a split seesaw model with one lighter right-handed neutrino but two heavier right-handed neutrinos which can realize the AIT ansatz and accommodate a successful leptogenesis simultaneously. We first give the condition on the neutrino Yukawa couplings for realizing the AIT ansatz, discuss its realization by employing an Abelian flavor symmetry, and study its implications for the mixing of the lighter right-handed neutrino with three left-handed neutrinos. We then successively study the implications for leptogenesis of the interesting scenarios where M_{{textrm{D}}} is a triangular matrix (which has maximally-restricted texture zeros, in line with the simplicity principle) or respects the mu -tau reflection symmetry (which is well motivated by the experimental results), on top of the AIT ansatz.

Use of Gastrointestinal Simulator, Mass Transport Analysis, and Absorption Simulation to Investigate the Impact of pH Modifiers in Mitigating Weakly Basic Drugs' Performance Issues Related to Gastric pH: Palbociclib Case Study.

It is well known that reduced gastric acidity, for example with concomitant administration of acid reducing agents, can result in variable pharmacokinetics and decreased absorption of weakly basic drugs. It is important to identify the risk of reduced and variable absorption early in development, so that product design options to address the risk can be considered. This article describes the utilization of in vitro and in silico tools to predict the effect of gastric pH, as well as the impact of adding pH modifiers, in mitigating the effect of acid reducing agents on weak base drugs' dissolution and absorption. Palbociclib, a weakly basic drug, was evaluated in low and high gastric pH conditions in a multicompartmental dissolution apparatus referred to as a gastrointestinal simulator (GIS). The GIS permits the testing of pharmaceutical products in a way that better assesses dissolution under physiologically relevant conditions of pH, buffer concentration, formulation additives, and physiological variations including GI pH, buffer concentrations, secretions, stomach emptying rate, residence time in the GI, and aqueous luminal volume. To predict drug dissolution in the GIS, a hierarchical mass transport model was used and validated using in vitro experimental data. Dissolution results were then compared to observed human clinical plasma data with and without proton pump inhibitors using a GastroPlus absorption model to predict palbociclib plasma profiles and pharmacokinetic parameters. The results showed that the in silico model successfully predicted palbociclib dissolution in the GIS under low and high gastric pH conditions with and without pH modifiers. Furthermore, the GIS data coupled with the in silico tools anticipated (1) the reduced palbociclib exposure due to proton pump inhibitor coadministration and (2) the mitigating effect of a pH-modifying agent. This study provides tools to help in the development of orally administered formulations to overcome the effect of elevated gastric pH, especially when formulating with pH modifiers.

Hiding neutrinoless double beta decay in the minimal seesaw model with the TM1 or μ–τ reflection symmetry

In Asaka et al (2021 Phys. Rev. D 103, 015014), Asaka, Ishida and Tanaka put forward an interesting possibility that the neutrinoless double beta decay can be hidden in the minimal seesaw model with the two right-handed neutrinos having a hierarchical mass structure: the lighter one is lighter enough than the typical Fermi-momentum scale of nuclei while the heavier one is sufficiently heavy to decouple from the neutrinoless double beta decay. Then, in the basis where the mass matrices of the charged leptons and right-handed neutrinos are diagonal, for some particular texture of the Dirac neutrino mass matrix , the neutrinoless double beta decay can be hidden. In this paper, on top of this specified model, we study the interesting scenario that further obeys the TM1 symmetry or μ–τ reflection symmetry which are well motivated by the experimental results for the neutrino mixing parameters.

Graphite/SnSe hybrid-embedded monolithic foams with hierarchical and bimodal pores for high performance solar desalination membranes with spontaneous salt rejection

Solar water evaporation techniques have attracted considerable interest due to their strong potential to disrupt existing desalination systems. As the interfaical solar steam generation has been heavily studied to explore the strategies to increase light absorption, recent effort has been focused on the development of mass transfer-based interfacial layer. Here, we propose monolithic solar evaporator (MSE) having a hierarchical mass transfer layer made of a melamine foam skeleton coated with graphite and tin selenide photothermal materials (G-SnSe). Unlike conventional solar evaporator structures consisting of double or three layers, the MSE has a monolithic configuration on top of wihch G-SnSe forms the bimodal porous structure (50–60% porosity) for enhancing the mass transfer. Due to the reinforced capillarity at the small-scale pores in the bimodal structure, the MSE structure achieves a high evaporation rate of 1.303 kg m-2h−1 when exposed to 1 sun irradiation. Furthermore, large-scale pores in the bimodal structures would simultaneously promote the autonomous rejection of salts at the MSE surface during solar desalination. We show that optimizing the bimodally porous structure and the interfacial properties significantly improves the solar evaporation efficiency, demonstrating the intricated structure for the next generation solar evaporation and desalination systems.

Multi-chaotic inflation with and without spectator field

Motivated by the result of Planck+BICEP/Keck recently released, we investigate the consistency of the multi-field inflation models in terms of the spectral index ns and the tensor-to-scalar ratio r. In this study, we focus on double-inflaton models with and without a spectator field.We find that inflaton with a quadratic potential can become viablewhen three fields with a specific hierarchical mass spectrum are realized such that two fields act as inflatons and the other one is the spectator. We also discuss the conditions to avoid the fine-tuning, by careful study of how the prediction depends on the background trajectory in the inflaton-field space.

Gravitational wave imprints of left-right symmetric model with minimal Higgs sector

We study the gravitational wave imprints of left-right symmetric model equipped with universal seesaw mechanism allowing for the natural generation of hierarchical masses of the Standard Model fermions. The scalar sector of this model is the minimal one, consisting of only two Higgs doublets. Following the construction of the full thermal potential for this model, we perform a scan of the entire parameter space and identify the region in which the cosmic phase transition associated with the left-right symmetry breaking gives gravitational wave signals detectable by a variety of planned space-based interferometers. Then we also discuss the relevant collider implications of this beyond the Standard Model scenario.