Energy Scale Research Articles

QCD running in lepton number violating meson and tau decays

Below the electroweak scale, new physics that violates the lepton number in two units (ΔL=2) and is mediated by heavy particle exchange can be parametrized by a dimension-nine low-energy effective Lagrangian. Operators in this Lagrangian involving first-generation quarks and leptons contribute to the short-range mechanism of neutrinoless double beta decay (0νββ) and therefore they are strongly constrained. On the other hand, operators with other quark and lepton families are bounded by the nonobservation of different lepton number violating meson and tau decays, such as M1−→M2+ℓ1−ℓ2− and τ−→ℓ+M1−M2−. In this work, we calculate renormalization-group-evolution (RGE)-improved bounds on the Wilson coefficients involved in these decays. We calculate QCD corrections to the dimension-nine operator basis and find RGE matrices that describe the evolution of the Wilson coefficients across different energy scales. Unlike the running of operators involved in 0νββ decay, the general flavor structure leads to the mixing of not only different Lorentz structures but also of different quark-flavor configurations. Additionally, operators that vanish for the identical lepton case need to be added to the operator basis. We find new constraints on previously unbounded operators and the enhancement of bounds for specific Wilson coefficients. We also find new bounds coming from the mixing between operators with different quark-flavor configurations. Published by the American Physical Society 2025

The irreducibility of chemistry to Everettian quantum mechanics

Abstract The question of whether chemical structure is reducible to Everettian Quantum Mechanics (EQM) should be of interest to philosophers of chemistry and philosophers of physics alike. Among the three realist interpretations of quantum mechanics, EQM resolves the measurement problem by claiming that measurements (now interpreted as instances of decoherence) have indeterminate outcomes absolutely speaking, but determinate outcomes relative to emergent worlds—Maudlin (Topoi, 14:7-15, 1995). Philosophers who wish to be sensitive to the practice of quantum chemistry e.g. Scerri (The changing views of a philosopher of chemistry on the question of reduction, 2016) should be interested in EQM because Franklin and Seifert (J. Philos. Sci, 2020) claim that resolving the measurement problem also resolves the reducibility of chemical structure, and EQM is the interpretation which involves no mathematical structure beyond that used by practicing scientists. Philosophers interested in the quantum interpretation debate should be interested in the reducibility of chemistry because chemical structure is precisely the kind of determinate three-dimensional fact which EQM should be able to ground if it is to be empirically coherent—see Allori (Quantum Rep, 5:80-101, 2023). The prospects for reduction of chemical structure are poor if it cannot succeed in EQM; the prospects for EQM as a guide to ontology are poor if it cannot reduce chemical structure. Unfortunately for proponents of chemical reduction and EQM, there are three serious barriers to the reduction of chemistry to EQM. The first concern is that quantum treatments of chemical structure rely on the Born-Oppenheimer approximation, which holds nuclear locations fixed while minimizing the energy of the electronic configuration—Hendry (Philosophical Perspectives in Quantum Chemistry, 147-172, 2022), but this approximation is not licensed by EQM. The Born-Oppenheimer approximation relies on nuclei and molecular orbitals being simultaneously present, but in the three-dimensional ontology following from the Everett interpretation these only emerge at different energy scales and are not simultaneously present—Miller (Found. Chem, 25:405-417, 2023). The second concern is that the emergent worlds of EQM are supposed to be decoherent at the macro-scale—Wilson (The Nature of Contingency: Quantum Physics as Modal Realism 2020), but the recent development of superchemistry suggests that chemical reactions can occur in coherent states—Zhang et al. (Nat. Phys, 1-5, 2023). The third concern is that emergent worlds are only pragmatic pseudo-processes—Wallace (The Emergent Multiverse: Quantum Theory According to the Everett Interpretation, 2012b), but this means EQM trades realist physics for mere instrumentalism about chemistry. Absent a commitment to chemical realism, reduction is an empty promise. The prospects for reduction of chemical structure to EQM are therefore poor.

Proximal femur segmentation and quantification in dual-energy subtraction tomosynthesis: A novel approach to fracture risk assessment

Background Osteoporosis is a major public health concern, especially among older adults, due to its association with an increased risk of fractures, particularly in the proximal femur. These fractures severely impact mobility and quality of life, leading to significant economic and health burdens. Objective This study aims to enhance bone density assessment in the proximal femur by addressing the limitations of conventional dual-energy X-ray absorptiometry through the integration of tomosynthesis with dual-energy applications and advanced segmentation models. Methods and Materials The imaging capability of a radiography/fluoroscopy system with dual-energy subtraction was evaluated. Two phantoms were included in this study: a tomosynthesis phantom (PH-56) was used to measure the quality of the tomosynthesis images, and a torso phantom (PH-4) was used to obtain proximal femur images. Quantification of bone images was achieved by optimizing the energy subtraction (ene-sub) and scale factors to isolate bone pixel values while nullifying soft tissue pixel values. Both the faster region-based convolutional neural network (Faster R-CNN) and U-Net were used to segment the proximal femoral region. The performance of these models was then evaluated using the intersection-over-union (IoU) metric with a torso phantom to ensure controlled conditions. Results The optimal ene-sub-factor ranged between 1.19 and 1.20, and a scale factor of around 0.1 was found to be suitable for detailed bone image observation. Regarding segmentation performance, a VGG19-based Faster R-CNN model achieved the highest mean IoU, outperforming the U-Net model (0.865 vs. 0.515, respectively). Conclusions These findings suggest that the integration of tomosynthesis with dual-energy applications significantly enhances the accuracy of bone density measurements in the proximal femur, and that the Faster R-CNN model provides superior segmentation performance, thereby offering a promising tool for bone density and osteoporosis management. Future research should focus on refining these models and validating their clinical applicability to improve patient outcomes.

Toward a Future-Facing Climate Policy

This Article provides a systems analysis of climate change policy that links together subsystems relating to innovation, energy economics, interest group politics, and government regulation. It is easy but misleading to equate climate policy with emissions regulation. That is too narrow a frame. We urgently need a new energy system because of climate change, but regulating carbon emissions is only one part of a bigger project. We cannot assume that as carbon emissions decline a new energy system will build itself—nor will society be willing to eliminate fossil fuels without confidence in their replacements. An effective climate policy requires much more than simply restricting fossil fuels and hoping the market will fill the gap. The energy transition requires incentives for energy research, development, and scaling up new energy technologies. For the energy transition to happen, we also need sufficiently large-scale deployment to trigger economies of scale and learning by doing. There is much to be gained, then, from shifting the paradigm from emissions reduction to the energy transition. To make a homely analogy: The reason for a kitchen renovation may be dry rot, and the first step is ripping out rotten wood. But the point of the remodeling is putting in a new kitchen, not just getting rid of the rot.

Search for a massless dark photon in c→uγ′ decays

Using 7.9fb−1 of e+e− collision data collected at s=3.773 GeV with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes D0→ωγ′ and D0→γγ′ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be 1.1×10−5 and 2.0×10−6 for D0→ωγ′ and D0→γγ′, respectively. These results provide the most stringent constraint on the new physics energy scale associated with cuγ′ coupling in the world, with the new physics energy scale related parameter |C|2+|C5|2<8.2×10−17 GeV−2 at the 90% confidence level. Published by the American Physical Society 2025

New models of quintessential inflation featuring plateau and hilltop potentials

We introduce a new class of hilltop and plateau potentials which can successfully unify inflation and dark energy resulting in quintessential inflation (QI). Interestingly these new potentials are related through an inverse transformation. Namely, if V(ϕ)=V0v(ϕ) is a plateau potential then the inverse potential V(ϕ)=V0v(ϕ)-1 describes hilltop QI. A simple example is provided by the KKLT-inspired potential v(ϕ)=M2n+ϕ2nN2n+ϕ2n. When M/N≪1 this potential describes plateau QI, while its inverse, v(ϕ)-1 describes hilltop QI. Other simple models of QI arise for the class of potentials V(ϕ)∼exp∓f(ϕ), where the − (+) sign is associated with a plateau (hilltop). A key feature of this new class of QI models is the near absence of small dimensionless parameters, or small mass parameters (relative to the energy scale of the Standard Model of particle physics) – which are usually associated with the presence of dark energy. A forecast for the gravitational wave background generated in these models is provided.

Photospheric Swirls in a Quiet-Sun Region

Abstract Swirl-shaped flow structures have been observed throughout the solar atmosphere, in both emission and absorption, at different altitudes and locations, and are believed to be associated with magnetic structures. However, the distribution patterns of such swirls, especially their spatial positions, remain unclear. Using the Automated Swirl Detection Algorithm, we identified swirls from the high-resolution photospheric observations, centered on Fe i 630.25 nm, of a quiet region near the Sun's central meridian by the Swedish 1-m Solar Telescope. Via a detailed study of the locations of the detected small-scale swirls with an average radius of ~300 km, we found that most of them are located in lanes between mesogranules (which have an average diameter of ~5.4 Mm) instead of the commonly believed intergranular lanes. The squared rotation, expansion/contraction and vector speeds, and proxy kinetic energy are all found to follow Gaussian distributions. Their rotation speed, expansion/contraction speed, and circulation are positively correlated with their radius. All these results suggest that photospheric swirls at different scales and locations across the observational 56 . ″ 5 × 57 . ″ 5 field of view could share the same triggering mechanism at preferred spatial and energy scales. A comparison with our previous work suggests that the number of photospheric swirls is positively correlated with the number of local magnetic concentrations, stressing again the close relation between swirls and local magnetic concentrations: the number of swirls should positively correlate with the number and strength of local magnetic concentrations.

Pumped hydro energy storage to support 100% renewable energy

Abstract The rapidly growing scale of solar photovoltaics and wind energy coupled with electrification of transport, heating and industry offers an affordable pathway for achieving deep decarbonization. Massive integration of variable solar photovoltaics and wind energy requires large-scale adoption of short (seconds-hours) and long (hours-days) duration energy storage. Currently, long-duration pumped hydro energy storage (PHES) accounts for about 95% of global energy storage for the electricity sector. This paper discusses the Global PHES Atlases developed by the Australian National University which identify 0.8 million off-river (closed-loop) PHES sites with a combined 86 million Gigawatt-hours of storage potential, which is about 3 years of current global electricity production. These Atlases show that most global jurisdictions have vast potential for low-cost PHES with small water and land requirements, and that do not require new dams on rivers. The low capital cost of premium PHES systems ($ per kilowatt-hour) is pointed out. Methods for creating shortlists of promising PHES sites from the Atlases for detailed investigation are developed.

The Multiscale physics behind the Rikitake time, general friction law, and precursory-coseismic energy scaling

The Multiscale physics behind the Rikitake time, general friction law, and precursory-coseismic energy scaling

Watt-class silicon photonics-based optical high-power amplifier

AbstractHigh-power amplifiers are critical components in optical systems spanning from long-range optical sensing and optical communication systems to micromachining and medical surgery. Today, integrated photonics with its promise of large reductions in size, weight and cost cannot be used in these applications, owing to the lack of on-chip high-power amplifiers. Integrated devices severely lack in output power owing to their small size, which limits their energy storage capacity. For the past two decades, large mode area (LMA) technology has played a disruptive role in fibre amplifiers, enabling a dramatic increase of output power and energy by orders of magnitude. Owing to the ability of LMA fibres to support significantly larger optical modes, the energy storage and power handling capabilities of LMA fibres have significantly increased. Therefore, an LMA device on an integrated platform can play a similar role in power and energy scaling of integrated devices. In this work, we demonstrate LMA waveguide-based watt-class high-power amplifiers in silicon photonics with an on-chip output power exceeding ~1 W within a footprint of only ~4.4 mm2. The power achieved is comparable and even surpasses that of many fibre-based amplifiers. We believe that this work has the potential to radically change the integrated photonics application landscape, allowing power levels previously unimaginable from an integrated device to replace much of today’s benchtop systems. Moreover, mass producibility, reduced size, weight and cost will enable yet unforeseen applications of laser technology.

Redesign of Virtual Power Plant-led Electricity Demand Response Program

As the scale of renewable energy on the demand side continues to grow, a new demand response program (DRP), the virtual power plant (VPP), pays a rebate to the consumer and purchases his rooftop solar electricity. This electricity is dispatched to areas of electricity shortages, which is vital in balancing electricity loads and avoiding energy waste. However, the new DRP differs from the traditional DRP in terms of paying rebates. The traditional DRP requires consumers to respond above a specified baseline to receive a rebate. In contrast, in the new DRP, consumers can receive a rebate even if their response is small (i.e., no baseline). There is no research that addresses this divergence. Therefore, we construct a supply chain consisting of a consumer and a VPP for this novel DRP and analyze the strategic interactions between them in two situations where a baseline is not set/set. Our results show room for improvement in the DRP that dispatches electricity generated from rooftop solar. If the consumer generates more electricity from rooftop solar, the baseline, rather than frustrating the consumer, motivates the consumer to be more responsive. While the baseline also discourages the demand response process, it reduces the emissions generated from the consumer’s over-responsiveness. Additionally, our study suggests that a baseline, whether it facilitates or hinders the DRP, could benefit the VPP, depending on the business model of the VPP. In addition, we add several extensions to demonstrate the robustness of our model.

Mechanistic basis of temperature adaptation in microtubule dynamics across frog species.

Cellular processes are remarkably effective across diverse temperature ranges, even with highly conserved proteins. In the context of the microtubule cytoskeleton, which is critically involved in a wide range of cellular activities, this is particularly striking, as tubulin is one of the most conserved proteins while microtubule dynamic instability is highly temperature sensitive. Here, we leverage the diversity of natural tubulin variants from three closely related frog species that live at different temperatures. We determine the microtubule structure across all three species at between 3.0 and 3.6Å resolution by cryo-electron microscopy and find small differences at the β-tubulin lateral interactions. Using invitro reconstitution assays and quantitative biochemistry, we show that tubulin's free energy scales inversely with temperature. The observed weakening of lateral contacts and the low apparent activation energy for tubulin incorporation provide an explanation for the overall stability and higher growth rates of microtubules in cold-adapted frog species. This study thus broadens our conceptual framework for understanding microtubule dynamics and provides insights into how conserved cellular processes are tailored to different ecological niches.

Angular dependent measurement of electron-ion recombination in liquid argon for ionization calorimetry in the ICARUS liquid argon time projection chamber

This paper reports on a measurement of electron-ion recombination in liquid argon in the ICARUS liquid argon time projection chamber (LArTPC). A clear dependence of recombination on the angle of the ionizing particle track relative to the drift electric field is observed. An ellipsoid modified box (EMB) model of recombination describes the data across all measured angles. These measurements are used for the calorimetric energy scale calibration of the ICARUS TPC, which is also presented. The impact of the EMB model is studied on calorimetric particle identification, as well as muon and proton energy measurements. Accounting for the angular dependence in EMB recombination improves the accuracy and precision of these measurements.

Observation and Research on Cosmic Ray Muons and Solar Modulation Effect Based on Plastic Scintillator Detector

Cosmic rays, originating from celestial phenomena such as stars, supernovae, and other astrophysical sources, are composed of high-energy particles that enter Earth’ s atmosphere. Upon interaction with atmospheric nuclei, these primary cosmic rays generate an array of secondary particles, with muons constituting the dominant component at ground level. Muons, due to their relative abundance, stability, and well-characterized energy loss mechanisms, serve as critical probes for investigating the fundamental properties of cosmic rays. Studies of muon energy distribution, diurnal anisotropy, and their modulation by solar activity provide essential insights into the mechanisms of particle acceleration in cosmic ray sources and the influence of solar and atmospheric effects.<br>This study aims to characterize the counting spectrum and anisotropic properties of cosmic ray muons using a plastic scintillator detector system. The experiment was conducted over a three-month period, from December 2023 to February 2024, leveraging long-bar plastic scintillator detectors equipped with dual-end photomultiplier tubes (PMTs) and a high-resolution digital data acquisition system. A dual-end coincidence measurement technique was implemented to enhance the signal-to-noise ratio by suppressing thermal noise and other background interferences. Comprehensive calibration of the detection system was performed using standard gamma-ray sources, including <sup>137</sup>Cs, <sup>60</sup>Co, and <sup>40</sup>K, ensuring precise energy scaling and reliable performance.<br>The observed energy spectrum of cosmic ray muons showed excellent agreement with theoretical predictions, accounting for the energy losses incurred as muons traverse the detector. Diurnal variations in muon count rates revealed a pronounced pattern, with a systematic reduction observed between 8:00 AM and 1:00 PM. This phenomenon is attributed to solar shielding effects, wherein enhanced solar activity during daytime hours modulates the flux of galactic cosmic rays reaching Earth’ s surface. To account for atmospheric influences, meteorological corrections were applied using temperature and pressure adjustment functions derived from regression analysis. These corrections revealed that atmospheric pressure and temperature are significant factors influencing muon count rates, with clear linear relationships observed.<br>The study further corroborated these findings through cross-comparisons with data from the Yangbajing Cosmic Ray Observatory. Minor discrepancies, primarily in low-energy muon count rates, were attributed to variations in detector sensitivities and local atmospheric conditions. These observations underscore the robustness of the plastic scintillator detector system for capturing detailed muon spectra and anisotropic patterns.<br>In conclusion, this research establishes a reliable experimental framework for analyzing cosmic ray muons and their modulation by solar and atmospheric phenomena. The results contribute to a deeper understanding of cosmic ray anisotropy and the interplay between astrophysical and geophysical processes. Furthermore, the findings provide valuable insights for optimizing detection technologies and enhancing the accuracy of cosmic ray studies.

Probing the shape of the primordial curvature power spectrum and the energy scale of reheating with pulsar timing arrays

Probing the shape of the primordial curvature power spectrum and the energy scale of reheating with pulsar timing arrays

On-chip cryogenic low-pass filters based on finite ground-plane coplanar waveguides for quantum measurements.

Quantum technology exploits fragile quantum electronic phenomena whose energy scales demand ultra-low electron temperature operation. The lack of electron-phonon coupling at cryogenic temperatures makes cooling the electrons down to a few tens of millikelvin a non-trivial task, requiring extensive efforts on thermalization and filtering high-frequency noise. Existing techniques employ bulky and heavy cryogenic metal-powder filters, which prove ineffective at sub-GHz frequency regimes and unsuitable for high-density quantum circuits such as spin qubits. In this work, we realize ultra-compact and lightweight on-chip cryogenic filters based on the attenuation characteristics of finite ground-plane coplanar waveguides. These filters are made of aluminum on sapphire substrates using standard microfabrication techniques. The attenuation characteristics are measured down to a temperature of 500 mK in a dilution refrigerator in a wide frequency range of a few hundred kHz to 8.5GHz. We find their performance is superior by many orders compared to the existing filtering schemes, especially in the sub-GHz regime, negating the use of any lumped-element low-pass filters. The compact and scalable nature makes these filters a suitable choice for high-density quantum circuits such as quantum processors based on quantum dot spin qubits.

Characterization of 3D printed micro-blades for cutting tissue-embedding material.

Cutting soft materials on the microscale has emerging applications in single-cell studies, tissue microdissection for organoid culture, drug screens, and other analyses. However, the cutting process is complex and remains incompletely understood. Furthermore, precise control over blade geometries, such as the blade tip radius, has been difficult to achieve. In this work, we use the Nanoscribe 3D printer to precisely fabricate micro-blades (i.e., blades <1 mm in length) and blade grid geometries. This fabrication method enables a systematic study of the effect of blade geometry on the indentation cutting of paraffin wax, a common tissue-embedding material. First, we print straight micro-blades with tip radius ranging from ~100 nm to 10 μm. The micro-blades are mounted in a custom nanoindentation setup to measure the cutting energy during indentation cutting of paraffin. Cutting energy, measured as the difference in dissipated energy between the first and second loading cycles, decreases as blade tip radius decreases, until ~357 nm when the cutting energy plateaus despite further decrease in tip radius. Second, we expand our method to blades printed in unconventional configurations, including parallel blade structures and blades arranged in a square grid. Under the conditions tested, the cutting energy scales approximately linearly with the total length of the blades comprising the blade structure. The experimental platform described can be extended to investigate other blade geometries and guide the design of microscale cutting of soft materials.

130 μJ linear-polarized single-frequency 12-μm-core Er/Yb co-doped fiber amplifier based on pre-shaped seed pulse

&lt;sec&gt;Stimulated Brillouin scattering (SBS) is the major barrier in the process of energy scaling for pulsed single-frequency fiber master oscillator power amplifier (MOPA). Due to gain saturation effect, the laser pulse profile will be gradually distorted with the increase of pump power, which induces steep leading edge and narrower width for the amplified pulses. The resulting laser peak power would increase rapidly and thus the SBS threshold is reached earlier to limit the amplification of pulse energy.&lt;/sec&gt;&lt;sec&gt;A method to obtain high-energy pulsed single-frequency laser by pulse pre-shaping is demonstrated in this work. By designing the leading edge of the triangular pulse, optimizing its rising trend and the duration of the low-intensity rising part, the pulse width compression phenomenon caused by gain saturation is alleviated effectively. Thereafter, the laser peak power increase process can be retarded to reach the SBS threshold so that higher energy can be amplified for the pulsed single-frequency fiber laser. In the experiment, when the seed pulse is optimized to be a triangular pulse with a low-intensity rising edge of 401 ns and a pulse width of 520 ns, a linear-polarized pulse single-frequency fiber laser of 130.9 μJ is obtained in a 12-μm-core Er/Yb co-doped polarization-maintaining fiber. The pulse width is broadened to 608 ns at the maximum energy. When it is compared with the triangular pulse seed with a rapidly rising leading edge, its maximum energy is increased by about 25%. The optical signal-to-noise ratio and polarization extinction ratio are measured to be 42 dB and 16 dB at the maximum pulse energy, respectively. The corresponding spectral linewidth measured by a delayed self-heterodyne system is 542 kHz. Higher pulse energy can be anticipated by further optimizing the pulse profile and using large-mode-are gain fibers.&lt;/sec&gt;

Short-range order and hidden energy scale in geometrically frustrated magnets

In geometrically frustrated (GF) magnets, conventional long-range order is suppressed due to the presence of primitive triangular structural units, and the nature of the ensuing ground state remains elusive.

Structural analysis of socioeconomic factors and school jet lag in traumatic dental injury among children.

The objective of this study was to analyze the directions by which school jet lag is associated with traumatic dental injury in children, evaluating direct and indirect effects of socioeconomic factors and sleep. A representative, population-based, cross-sectional study was conducted with 739 schoolchildren eight to ten years of age. Parents/guardians answered a sociodemographic questionnaire, the Sleep Disturbance Scale for Children and the Circadian Energy Scale. Four examiners underwent training and calibration exercises for the diagnosis of traumatic dental injury (K > 0.80) using the criteria proposed by Andreasen (2007). Descriptive analysis was followed by structural equation modeling to determine direct and indirect associations between the variables incorporated into the theoretical model. School jet lag [standardized coefficient (SC): -0.238, 95%CI: -0.390-0.087], income (SC: -0.151, 95%CI: 0.0010-0.292), and number of residents in the home (SC: -0.109, 95%CI: -0.212-0.007) were directly associated with traumatic dental injury, whereas sleep disturbances and schooling of the parents/guardians exerted an indirect effect. Sociodemographic factors and school jet lag were associated with traumatic dental injury in children eight to ten years of age.