Physics Tomorrow Theoretical Physics Letters (TPL) An SCI-indexed monthly thrice peer-reviewed journal.

March 5, 2024 at 7:00:00 PM

Electronic and thermal sequential transport in metallic and superconducting two-junction arrays

The description of transport phenomena in devices consisting of arrays of tunnel junctions, and the experimental confirmation of these predictions is one of the great successes of mesoscopic physics. The aim of this paper is to give a self-consistent review of sequential transport processes in such devices, based on the so-called ”orthodox” model. We calculate numerically the current-voltage (I–V ) curves, the conductance versus bias voltage (G–V ) curves, and the associated thermal transport in symmetric and asymmetric two-junction arrays such as Coulomb-blockade thermometers (CBTs), superconducting-insulator-normal-insulator-superconducting (SINIS) structures, and superconducting single-electron transistors (SETs). We investigate the behaviour of these systems at the singularity-matching bias points, the dependence of micro refrigeration effects on the charging energy of the island, and the effect of a finite superconducting gap on Coulomb-blockade thermometry.

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https://doi.wikipt.org/11/1490/3728tpl

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Electronic and thermal sequential, superconducting two-junction arrays, superconductor, tunnel junction, solid state devices, applied physics

Tunable structure-activity correlations of molybdenum dichalcogenides (MoX2; X=S, Se, Te) electrocatalysts via hydrothermal methods: insight into optimizing the electrocatalytic performance for hydrogen generation

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February 25, 2024 at 6:30:00 AM

Tunable structure-activity correlations of molybdenum dichalcogenides (MoX2; X=S, Se, Te) electrocatalysts via hydrothermal methods: insight into optimizing the electrocatalytic performance for hydrogen generation

Hydrogen Evolution Reaction (HER) has always gained wide attention as one of the eco-friendly and sustainable pathways for efficient hydrogen generation and storage; also, two-dimensional molybdenum dichalcogenide (MoX2, where X stands for S, Se, Te) layers have emerged as a class of quasi-ideal electrocatalysts because of their large surface area, rich reserves and outstanding conductivity. However, besides greater HER activity, the maturity and diversity of modification strategies result in a more puzzling relationship between electrocatalytic mechanisms and the corresponding practical performance. In this article, based on a comprehensive review of fundamentals, principles and interconnected similarities of the MoX2 family, we focus on the structure-activity correlation of layered MoX2 for HER enhancement via hydrothermal synthesis. This method is summarized from different experimental systems to efficiently modulate the crystal structure and surface for boosted HER activity. Here, with the adjustment of three key experimental parameters: the categories of MoX2, reaction temperature and the molar amount of added reactants, the optimum HER performance can be obtained at the best conditions (MoSe2 species, 180℃ and a vast ratio of the reductant or metal precursor), and more microscopically, a controlled structure-activity relationship can be inducted. This summary may pave a new path for the controllable synthesis and modification of MoX2-based catalyst materials.

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https://doi.wikipt.org/11/1490/874831tpl

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Theoretical Physics Letters, 2023 ° dd(mm) ° 6584-6621
https://www.wikipt.org/tphysicsletters
DOI: doi.wikipt.org/11/1490/3728tpl

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molybdenum dichalcogenides, structure-activity analysis, tunable, phase transition, active sites, hydrogen evolution;, hydrothermal

Probing supermassive black hole seed scenarios with gravitational wave measurements

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December 6, 2023 at 12:15:00 PM

Probing supermassive black hole seed scenarios with gravitational wave measurements

The process whereby the supermassive black holes populating the centers of galaxies have been assembled remains to be established, with the relative importance of seeds provided by collapsed Population-III stars, black holes formed in nuclear star clusters via repeated mergers, or direct collapses of protogalactic disks yet to be determined. In this paper we study the prospects for casting light on this issue by future measurements of gravitational waves emitted during the inspirals and mergers of pairs of intermediate-mass black holes, discussing in particular the roles of prospective measurements by LISA and the proposed atom interferometers AION and AEDGE.

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Theoretical Physics Letters
2023 ° 18(06) ° 0631-3657
https://www.wikipt.org/tphysicsletters
DOI: https://doi.wikipt.org/11/1490/874831tpl

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primordial black holes, supermassive black hole, : galaxies – polarization, large-scale structure of Universe

Protoplanetary disks in Ks-band total intensity and polarized light

doi.wikipt.org/10/1490/3486tpl

Citation (36)

https://doi.wikipt.org/10/1490/4506tpl

October 13, 2023 at 12:15:00 PM

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Protoplanetary disks in Ks-band total intensity and polarized light

Abstract

Diverse morphology in protoplanetary disks can result from planet-disk interaction, suggesting the presence of forming planets. Characterizing disks can inform the formation environments of planets. To date, most imaging campaigns have probed the polarized light from disks, which is only a fraction of the total scattered light and not very sensitive to planetary emission. Aims. We aim to observe and characterize protoplanetary disk systems in the near-infrared in both polarized and total intensity light, to carry out an unprecedented study of the dust scattering properties of disks, as well as of any possible planetary companions. Methods. Using the star-hopping mode of the SPHERE instrument at the Very Large Telescope, we observed 29 young stars hosting protoplanetary disks and their reference stars in the Ks-band polarized light. We extracted disk signals in total intensity by removing stellar light using the corresponding reference star observations, by adopting the data imputation concept with sequential non-negative matrix factorization (DI-sNMF).

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Theoretical Physics Letters
2023 ° 03(10) ° 0631-3486
https://www.wikipt.org/tphysicsletters

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protoplanetary disks, – planets and satellites, high angular resolution, : image processing, astrophysics, space science

Searching for H→hh→bb¯ττ in the 2HDM Type-I at the LHC

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October 7, 2023 at 10:15:00 AM

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Searching for H→hh→bb¯ττ in the 2HDM Type-I at the LHC

Abstract

Unlike other realisations of the 2-Higgs Doublet Model (2HDM), the so-called Type-I allows for a very light Higgs boson spectrum. Specifically, herein, the heaviest of the two CP-even neutral Higgs states, H, can be the one discovered at the Large Hadron Collider (LHC) in 2012, with a mass of ≈ 125 GeV and couplings consistent with those predicted by the Standard Model (SM). In such a condition of the model, referred to as ‘inverted mass hierarchy’, the decay of the SM-like Higgs state into pairs of the lightest CP-even neutral Higgs boson, h, is possible, for masses of the latter ranging from MH/2 ≈ 65 GeV down to 15 GeV or so, all compatible with experimental constraints. In this paper, we investigate the scope of the LHC in accessing the process gg → H → hh → b ¯bτ τ by performing a Monte Carlo (MC) analysis aimed at extracting this signal from the SM backgrounds, in presence of a dedicated trigger choice and kinematic selection. We prove that some sensitivity to such a channel exists already at Run 3 of the LHC while the High-Luminosity LHC (HL-LHC) will be able to either confirm or disprove this theoretical scenario over sizable regions of its parameter space.

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9.2

Theoretical Physics Letters
2023 ° 03(10) ° 0631-4506
https://www.wikipt.org/tphysicsletters
DOI: https://doi.wikipt.org/10/1490/4506tpl

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astronomy, large hadron collider, lhc, elementary physics

Surface-Enhanced Raman Scattering from Au Nanorods, Nanotriangles, and Nanostars with Tuned Plasmon Resonances

doi.wikipt.org/10/1490/9586tpl

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October 3, 2023 at 11:45:00 AM

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Surface-Enhanced Raman Scattering from Au Nanorods, Nanotriangles, and Nanostars with Tuned Plasmon Resonances

Abstract

Electromagnetic theory predicts that the optimal value of the localized plasmon resonance (LPR) wavelength for the maximal SERS enhancement factor (EF) is half the sum of the laser and Raman wavelengths. For small Raman shifts, the theoretical EF scales as the fourth power of the local field. However, experimental data often disagree with these theoretical conclusions, leaving the question of choosing the optimal plasmon resonance for the maximal SERS signal unresolved. Here, we present experimental data for gold nanorods (AuNRs), gold nanotriangles (AuNTs), and gold nanostars (AuNSTs) simulating 1D, 2D, and 3D plasmonic nanostructures, respectively. The LPR wavelengths were tuned by chemical etching within 550 1050 nm at constant number concentrations of the particles. The particles were functionalized with Cy7.5 and NBT, and the dependence of the intensity at 940 cm-1 (Cy7.5) and 1343 cm-1 (NBT) on the LPR wavelength was examined for laser wavelengths of 633 nm and 785 nm. The electromagnetic SERS EFs were calculated by averaging the product of the local field intensities at the laser and Raman wavelengths over the particle surface and their random orientations. The calculated SERS plasmonic profiles were redshifted compared to the laser wavelength. For 785- nm excitation, the calculated EFs were five to seven times higher than those for 633-nm excitation. With AuNR@Cy7.5 and AuNT@ Cy7.5, the experimental SERS was 35-fold stronger than it was with NBT-functionalized particles, but with AuNST@Cy7.5 and AuNST@NBT, the SERS responses were similar. With all nanoparticles tested, the SERS plasmonic profiles after 785 nm excitation were slightly blue-shifted, as compared with the laser wavelength, possibly owing to the inner filter effect. After 633-nm excitation, the SERS profiles were redshifted, in agreement with EM theory. In all cases, the plasmonic EF profiles were much broadened compared to the calculated ones and did not follow the four-power law.

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9.2

Theoretical Physics Letters
2023 ° 03(10) ° 0631-9586
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/9586tpl

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8

gold nanorods, gold nanotriangles, gold nanostars, SERS, localized plasmon resonance, T-matrix and COMSOL simulations

Optical Cluster Cosmology with SDSS redMaPPer clusters and HSC-Y3 lensing measurements

doi.wikipt.org/10/1490/6587450tpl

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September 25, 2023 at 6:30:00 AM

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Optical Cluster Cosmology with SDSS redMaPPer clusters and HSC-Y3 lensing measurements

Abstract

We present cosmology results obtained from a blind joint analysis of the abundance, projected clustering, and weak lensing of galaxy clusters measured from the Sloan Digital Sky Survey (SDSS) redMaPPer cluster catalog and the Hyper-Suprime Cam (HSC) Year3 shape catalog. We present a full-forward model for the cluster observables, which includes empirical modeling for the anisotropic boosts on the lensing and clustering signals of optical clusters. We validate our analysis via mock cluster catalogs which include observational systematics, such as the projection effect and the effect of baryonic feedback, and find that our analysis can robustly constrain cosmological parameters in an unbiased manner without any informative priors on our model parameters. The joint analysis of our observables in the context of the flat ΛCDM model results in cosmological constraints for 𝑆8 ≡ 𝜎8 √︁ Ωm/0.3 = 0.816+0.041 −0.039. Our result is consistent with the 𝑆8 inference from other cosmic microwave background- and large scale structure-based cosmology analyses, including the result from the Planck 2018 primary CMB analysis.

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9.5

Theoretical Physics Letters
2023 ° 25(09) ° 0631-6901
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/6587450tpl

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large-scale structure of Universe, cosmology

A search for faint resolved galaxies beyond the Milky Way in DES Year 6: A new faint, diffuse dwarf satellite of NGC 55

doi.wikipt.org/10/1490/687400tpl

Citation (30)

September 11, 2023 at 3:15:00 PM

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A search for faint resolved galaxies beyond the Milky Way in DES Year 6: A new faint, diffuse dwarf satellite of NGC 55

Electromagnetic theory predicts that the optimal value of the localized plasmon resonance (LPR) wavelength for the maximal SERS enhancement factor (EF) is half the sum of the laser and Raman wavelengths. For small Raman shifts, the theoretical EF scales as the fourth power of the local field. However, experimental data often disagree with these theoretical conclusions, leaving the question of choosing the optimal plasmon resonance for the maximal SERS signal unresolved. Here, we present experimental data for gold nanorods (AuNRs), gold nanotriangles (AuNTs), and gold nanostars (AuNSTs) simulating 1D, 2D, and 3D plasmonic nanostructures, respectively. The LPR wavelengths were tuned by chemical etching within 550 1050 nm at constant number concentrations of the particles. The particles were functionalized with Cy7.5 and NBT, and the dependence of the intensity at 940 cm-1 (Cy7.5) and 1343 cm-1 (NBT) on the LPR wavelength was examined for laser wavelengths of 633 nm and 785 nm. The electromagnetic SERS EFs were calculated by averaging the product of the local field intensities at the laser and Raman wavelengths over the particle surface and their random orientations. The calculated SERS plasmonic profiles were redshifted compared to the laser wavelength. For 785- nm excitation, the calculated EFs were five to seven times higher than those for 633-nm excitation. With AuNR@Cy7.5 and AuNT@ Cy7.5, the experimental SERS was 35-fold stronger than it was with NBT-functionalized particles, but with AuNST@Cy7.5 and AuNST@NBT, the SERS responses were similar. With all nanoparticles tested, the SERS plasmonic profiles after 785 nm excitation were slightly blue-shifted, as compared with the laser wavelength, possibly owing to the inner filter effect. After 633-nm excitation, the SERS profiles were redshifted, in agreement with EM theory. In all cases, the plasmonic EF profiles were much broadened compared to the calculated ones and did not follow the four-power law.

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9

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9

Theoretical Physics Letters
2023 ° 10(09) ° 0631-8743
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/687400tpl

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9

galaxies, dwarf, low-surface brightness, astro-particles

Bayesian and frequentist investigation of prior effects in EFTofLSS analyses of full-shape BOSS and eBOSS data

doi.wikipt.org/10/1490/784031tpl

Citation (11)

September 11, 2023 at 6:45:00 AM

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Bayesian and frequentist investigation of prior effects in EFTofLSS analyses of full-shape BOSS and eBOSS data

Abstract

Previous studies based on Bayesian methods have shown that the constraints on cosmological parameters from the Baryonic Oscillation Spectroscopic Survey (BOSS) full-shape data using the Effective Field Theory of Large Scale Structure (EFTofLSS) depend on the choice of prior on the EFT nuisance parameters. In this work, we explore this prior dependence by adopting a frequentist approach based on the profile likelihood method, which is inherently independent of priors, considering data from BOSS, eBOSS and Planck. We find that the priors on the EFT parameters in the Bayesian inference are informative and that prior volume effects are important. This is reflected in shifts of the posterior mean compared to the maximum likelihood estimate by up to 1.0 σ (1.6 σ) and in a widening of intervals informed from frequentist compared to Bayesian intervals by factors of up to 1.9 (1.6) for BOSS (eBOSS) in the baseline configuration, while the constraints from Planck are unchanged. Our frequentist confidence intervals give no indication of a tension between BOSS/eBOSS and Planck. However, we find that the profile likelihood prefers extreme values of the EFT parameters, highlighting the importance of combining Bayesian and frequentist approaches for a fully nuanced cosmological inference. We show that the improved statistical power of future data will reconcile the constraints from frequentist and Bayesian inference using the EFTofLSS.

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9.6

Theoretical Physics Letters
2023 ° 11(09) ° 0631-7846
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/784031tpl

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Bayesian, EFTofLSS, f full-shape BOSS, eBOSS data, theoretical physics, mathematical physics

Rapid neutron star cooling triggered by accumulated dark matter

doi.wikipt.org/10/1490/584587tpl

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September 10, 2023 at 12:45:00 PM

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Rapid neutron star cooling triggered by accumulated dark matter

Abstract

We study the effect of asymmetric fermionic dark matter (DM) on the thermal evolution of neutron stars (NSs). No interaction between DM and baryonic matter is assumed, except the gravitational one. Using the two-fluid formalism, we show that DM accumulated in the core of a star pulls inwards the outer baryonic layers of the star, increasing the baryonic density in the NS core. As a result, it significantly affects the star’s thermal evolution by triggering an early onset of the dir ect Urca process and modifying the photon emission from the surface caused by the decrease of the radius. Thus, due to the gravitational pull of DM, the direct Urca process becomes kinematically allowed for stars with lower masses. Based on these results, we discuss the importance of NS observations at different distances from the Galactic center. Since the DM distribution peaks towards the Galactic center, NSs in this region are expected to contain higher DM fractions that could lead to a different cooling behavior.

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Theoretical Physics Letters
2023 ° 10(09) ° 0631-9870
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/584587tpl

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Neutron stars, neutron star cooling, dark matter, universal correlation

SpookyNet: Advancement in Quantum System Analysis through Convolutional Neural Networks for Detection of Entanglement

doi.wikipt.org/10/1490/585470tpl

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September 10, 2023 at 2:30:00 PM

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SpookyNet: Advancement in Quantum System Analysis through Convolutional Neural Networks for Detection of Entanglement

The application of machine learning models in quantum information theory has surged in recent years, driven by the recognition of entanglement and quantum states, which are the essence of this field. However, most of these studies rely on existing prefabricated models, leading to inadequate accuracy. This work aims to bridge this gap by introducing a custom deep convolutional neural network (CNN) model explicitly tailored to quantum systems. Our proposed CNN model, the so-called SpookyNet, effectively overcomes the challenge of handling complex numbers data inherent to quantum systems and achieves an accuracy of 98.5%. Developing this custom model enhances our ability to analyze and understand quantum states. However, first and foremost, quantum states should be classified more precisely to examine fully and partially entangled states, which is one of the cases we are currently studying. As machine learning and quantum information theory are integrated into quantum systems analysis, various perspectives, and approaches emerge, paving the way for innovative insights and breakthroughs in this field.

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