Electromagnetic Decay Research Articles

Limits on non-relativistic matter during Big-bang nucleosynthesis

Big-bang nucleosynthesis (BBN) probes the cosmic mass-energy density at temperatures ∼ 10 MeV to ∼ 100 keV. Here, we consider the effect of a cosmic matter-like species that is non-relativistic and pressureless during BBN. Such a component must decay; doing so during BBN can alter the baryon-to-photon ratio, η, and the effective number of neutrino species. We use light element abundances and the cosmic microwave background (CMB) constraints on η and Nν to place constraints on such a matter component. We find that electromagnetic decays heat the photons relative to neutrinos, and thus dilute the effective number of relativistic species to N eff < 3 for the case of three Standard Model neutrino species. Intriguingly, likelihood results based on Planck CMB data alone find Nν = 2.800 ± 0.294, and when combined with standard BBN and the observations of D and 4He give Nν = 2.898 ± 0.141. While both results are consistent with the Standard Model, we find that a nonzero abundance of electromagnetically decaying matter gives a better fit to these results. Our best-fit results are for a matter species that decays entirely electromagnetically with a lifetime τX = 0.89 sec and pre-decay density that is a fraction ξ = (ρX /ρ rad|10 MeV = 0.0026 of the radiation energy density at 10 MeV; similarly good fits are found over a range where ξτX 1/2 is constant. On the other hand, decaying matter often spoils the BBN+CMB concordance, and we present limits in the (τX ,ξ) plane for both electromagnetic and invisible decays. For dark (invisible) decays, standard BBN (i.e. ξ = 0) supplies the best fit. We end with a brief discussion of the impact of future measurements including CMB-S4.

Signature decay modes of the compact doubly-heavy tetraquarks [formula omitted] and [formula omitted]

Based on the expectations that the lowest-lying doubly-bottom tetraquark Tbbu¯d¯ (JP=1+) and the bottom-charm tetraquark Tbcu¯d¯ (JP=0+) are stable against strong and electromagnetic decays, we work out a number of semileptonic and non-leptonic weak decays of these hadrons, making use of the heavy quark symmetry. In doing this, we concentrate on the exclusive decays involving also tetraquarks in the final states, i.e., transitions such as Tbbu¯d¯→Tbcu¯d¯(ℓ−νℓ,h−) and Tbcu¯d¯→Tccu¯d¯(ℓ−νℓ,h−), where h−=π−,ρ−,a1−,Ds−,Ds⁎−. So far, only the JP=1+ tetraquark Tccu¯d¯ has been discovered, which we identify with the I=0Tcc+ object, compatible with JP=1+ and having the pole mass relative to the D⁎+D0 mass threshold and decay widths δm=M(Tcc+)−(M(D⁎+)+M(D0))=−360±40−0+4 keV and Γ(Tcc+)=48−14+2 keV. Experimental discoveries of the transitions worked out here, and related ones involving doubly-heavy baryons, will quantify the diquark-antidiquark component of these tetraquarks.

Mechanisms of Fundamental Electromagnetic Wave Radiation in the Solar Wind

Large-scale and long-term two-dimensional particle-in-cell simulations performed for parameters relevant to type III solar radio bursts have provided new results on the generation mechanisms of fundamental electromagnetic waves radiated at the plasma frequency ω p . The paper first considers the nonlinear wave interaction process of electromagnetic decay (EMD) in a homogeneous solar wind plasma with an electron-to-ion temperature ratio T e /T i > 1. The dynamics of ion-acoustic waves (dispersion, spectra, growth/damping) is studied, and signatures confirming the three-wave interactions (cross-bicoherence, correlations between waves’ phases and between waves' growths, resonance conditions) are provided. The decisive role played in EMD by the backscattered Langmuir waves coming from the electrostatic decay (ESD) is demonstrated. EMD can be triggered by ion acoustic waves coming from the two cascades of the faster and more intense ESD. The same study is then performed in a solar wind plasma with random density fluctuations. In this case, EMD is not suppressed but develops only within plasma regions of reduced or quasi-uniform density. It coexists with linear mode conversion (LMC) of Langmuir waves into electromagnetic radiation, which is the fastest and most prominent process, as well as with ESD. LMC can lead to enhanced occurrence of EMD in the early stage. Moreover, the impact of T e /T i on electromagnetic energy growth and saturation is shown to be rather weak. Ion-acoustic waves are heavily damped at T e ∼ T i , so that EMD is overcome by nonlinear induced scattering on thermal ions. In actual solar wind plasmas, EMD should be more easily observed in plasma regions weakly perturbed by the background density turbulence and where ion temperature is decreased.

A Case Study of the Integration of Ground-Based and Drone-Based Ground-Penetrating Radar (GPR) for an Archaeological Survey in Hulata (Israel): Advancements, Challenges, and Applications

This study delves into the fusion of ground-based and drone-based ground-penetrating radar (GPR) technologies in archaeological exploration. Set against the backdrop of the Hulata solar panel construction site in Israel, the research confronts daunting obstacles such as clayey soil, accurate detection of small objects, and the imperative of timely reporting crucial for construction management. The drone-based GPR, a testament to technological innovation, showcases remarkable adaptability to challenging terrains, dispelling doubts about electromagnetic wave decay in clayey soil. Methodologically, the study employs detailed orthophoto mapping and grid-type surveys. The correlation of the results significantly bolsters the reliability of archaeological discoveries, uncovering scattered artifacts buried approximately 1–1.5 m below the surface. Meticulous excavations validate the geophysical surveys, affirming the presence of structures constructed from boulders. The application at the Hulata site validates the adaptability of drone-based GPR in challenging terrains. It provides a swift, cost-effective, and minimally invasive alternative to traditional excavation techniques, thereby transforming the field of archaeology.

Improving the energy efficiency of industrial radio frequency heat treatment by optimizing electrode sizes and reversal cycles

Radio Frequency (RF) heating technology exhibits potential advantages in the heat treatment of bulky products. The influence of electrode size on the RF heating performance by the electric field distribution, electromagnetic loss density, and temperature distribution was evaluated. An electrode reversal device was developed, facilitating the cyclic reversal of the positive and negative electrodes and the effect of electrode reversal was also investigated. Simulation results showed an optimal heating uniformity when the ratio of electrode to product width is 1.4. At that time, the influence of stray electric field between the positive electrode and the cavity on the electromagnetic energy was minimal. The variation in loss angle tangent caused by temperature change was the primary reason for the fluctuation of the electromagnetic-thermal energy conversion efficiency within the same radio-frequency field. The electrode reversal dramatically improved the heating uniformity in the direction of electromagnetic energy decay. The temperature uniformity index (TUI) can be reduced by 32.79 % to 75.41 % with the shorter reversal cycle, but the service life of the device was also curtailed due to more mechanical motions. Considering the stability of the equipment and the heating performance, the optimum reversal cycle was chosen to be 420 s. In this case, the maximum TUI didn’t exceed 0.017, demonstrating better heating uniformity as compared with the commonly used for improving heating uniformity. In conclusion, a suitable electrode width and reversal cycle can effectively avoid the thermal offset effect of larger agricultural products during RF heating, thus improving the heating performance.

Electromagnetic and hadronic decay of fully heavy tetraquarks

Electromagnetic and hadronic decay of fully heavy tetraquarks

An Improved Strategy of Grid-Forming DFIG Based on Disturbance Rejection Stator Flux Control

Grid-forming (GFM) control are promising for doubly fed induction generator-based wind turbines (DFIG -Based WTs) due to its grid-support ability and stable operation when connected to weak grid. However, GFM-DFIG might suffer from instability under symmetrical grid fault, if its electromagnetic and synchronous dynamics are poor. Therefore, an improved strategy of GFM-DFIG based on disturbance rejection stator flux control (DRSFC) is proposed in this paper. The DRSFC consists of a PI-based rotor-current loop and an active disturbance rejection control (ADRC)-based stator-flux outer loop, and both the better electromagnetic performance and the steady-state voltage source operation are achieved. Besides, impacts of DRSFC on GFM-DFIG are exposed via small-signal and large-signal analysis, and the potential inertia in the inner control loops is revealed. It is suggested that this potential inertia is reshaped by DRSFC, so the impact of inner control loop on the synchronization of GFM-DFIG can be quantitatively studied and controlled. On this basis, a pair of asymmetrical compensation are designed to improve its electromagnetic decay and synchronous dynamic. Finally, experiments are carried out to verify the effectiveness of proposed strategy.

Decay property of the X(3842) as the ψ3(1D33) state

In this paper, the new particle X(3842) discovered by the LHCb Collaboration is identified to be the ψ3(13D3) state. We study its strong decays with the combination of the Bethe-Salpeter method and the P30 model. Its electromagnetic (EM) decay is also calculated by the Bethe-Salpeter method within the Mandelstam formalism. The strong decay widths are Γ[X(3842)→D0D¯0]=1.27 MeV and Γ[X(3823)→D+D−]=1.08 MeV, and the ratio is B[X(3842)→D+D−]/B[X(3823)→D0D¯0]=0.84. The EM decay width is Γ[X(3842)→χc2γ]=0.29 MeV. We also estimate the total width to be 2.87 MeV, which is in good agreement with the experimental data 2.79−0.86+0.86 MeV. Since the used relativistic wave functions include different partial waves, we also study the contributions of different partial waves in electromagnetic decay. Published by the American Physical Society 2024

Semileptonic and nonleptonic weak decays of $$\psi (1S,2S)$$ and $$\eta _{c}(1S,2S)$$ to $$D_{(s)}$$ in the covariant light-front approach

AbstractIn addition to the strong and electromagnetic decay modes, the $$\psi (1S,2S)$$ ψ ( 1 S , 2 S ) and $$\eta _{c}(1S,2S)$$ η c ( 1 S , 2 S ) can also decay via the weak interaction. Such weak decays can be detected by the high-luminosity heavy-flavor experiments. At present, some of the semileptonic and nonleptonic $$J/\Psi $$ J / Ψ weak decays have been measured at BESIII. Researching for these charmonium weak decays to $$D_{(s)}$$ D ( s ) meson can provide a platform to check of the standard model (SM) and probe new physics (NP). So we investigate the semileptonic and nonleptonic weak decays of $$\psi (1S,2S)$$ ψ ( 1 S , 2 S ) and $$\eta _{c}(1S,2S)$$ η c ( 1 S , 2 S ) to $$D_{(s)}$$ D ( s ) within the covariant light-front quark model (CLFQM). With form factors of the transitions $$\psi (1S,2S)\rightarrow D_{(s)}$$ ψ ( 1 S , 2 S ) → D ( s ) and $$\eta _{c}(1S,2S)\rightarrow D_{(s)}$$ η c ( 1 S , 2 S ) → D ( s ) calculated under the CLFQM, we predict and discuss some physical observables, such as the branching ratios, the longitudinal polarizations $$f_{L}$$ f L and the forward–backward asymmetries $$A_{FB}$$ A FB . One can find that the Cabibbo-favored semi-leptonic decay channels $$\psi (1\,S,2\,S)\rightarrow D_{s}^{-}\ell ^{+}\nu _{\ell }$$ ψ ( 1 S , 2 S ) → D s - ℓ + ν ℓ with $$\ell =e,\mu $$ ℓ = e , μ and the nonleptonic decay modes $$\psi (1S,2S)\rightarrow D_{s}^{-}\rho ^{+}$$ ψ ( 1 S , 2 S ) → D s - ρ + have relatively large branching ratios of the order $$\mathcal {O}(10^{-9})$$ O ( 10 - 9 ) , which are most likely to be accessible at the future high-luminosity experiments.

Inclusive, prompt and nonprompt J/ψ identification in proton-proton collisions at the Large Hadron Collider using machine learning

Studies related to J/ψ meson, a bound state of charm and anticharm quarks (cc¯), in heavy-ion collisions, provide genuine testing grounds for the theory of strong interaction, quantum chromodynamics. To better understand the underlying production mechanism, cold nuclear matter effects, and influence from the quark-gluon plasma, baseline measurements are also performed in proton-proton (pp) and proton-nucleus (p-A) collisions. The inclusive J/ψ measurement has contributions from both prompt and nonprompt productions. The prompt J/ψ is produced directly from the hadronic interactions or via feed down from directly produced higher charmonium states, whereas nonprompt J/ψ comes from the decay of beauty hadrons. In experiments, J/ψ is reconstructed through its electromagnetic decays to lepton pairs, in either e++e− or μ++μ− decay channels. In this work, for the first time, machine learning techniques are implemented to separate the prompt and nonprompt dimuon pairs from the background to obtain a better identification of the J/ψ signal for different production modes. The study has been performed in pp collisions at s=7 and 13 TeV simulated using 8. Machine learning models such as XGBoost and LightGBM are explored. The models could achieve up to 99% prediction accuracy. The transverse momentum (pT) and rapidity (y) differential measurements of inclusive, prompt, and nonprompt J/ψ, its multiplicity dependence, and the pT dependence of fraction of nonprompt J/ψ (fB) are shown. These results are compared to experimental findings wherever possible. Published by the American Physical Society 2024

Dilepton production in proton-proton reaction at 4.5 GeV with the HADES spectrometer

Spectra of dileptons emitted in hadron collisions are important tool to study electromagnetic decays of resonances and the validity of the Vector Meson Dominance model. Furthermore, they provide reference spectra for the hot and dense (heavy-ion A+A collisions) and cold nuclear matter (p+A collisions). In February 2022, proton-proton reactions at 4.5 GeV beam kinetic energy were measured by HADES experiment. The aim of the analysis is to study the specific channels that produced dileptons, such as baryonic resonance Dalitz decays (Δ/N* → Ne+e−) and vector meson decays (ρ/ω/φ→ e+e−). In addition, the investigations of dielectron production above the φ meson mass will be enabled. In this contribution, different steps of the e+e− pair reconstruc tion are discussed.

The FAIR Phase-0 Hyperon Program at HADES

Abstract. Hyperons are a unique probe to study the non-perturbative aspects of the strong interaction. At HADES, they are produced in proton or pion induced reactions at kinetic energies up to 4.5 GeV. Already in the past, HADES has shown its potential for hyperon physics, including λ polarization, λ-N interaction and measurements of the λ(1405) and λ(1520) line-shapes. The HADES detector has recently been extended with a forward detector, partly developed for the PANDA experiment, extending the acceptance for hyperon channels at forward angles. The PANDA@HADES initiative gives the opportunity for an even richer hyperon program. The current main objectives are the production of hyperon resonances, electromagnetic decays of hyperons with special focus on hyperon Dalitz decays and double strangeness production, including a λ – λ interaction study and ξ− production. First results from the ongoing studies promise a successful execution of the program. In the future, there is the possibility for a pion beam experiment with HADES, enabling further hyperon studies.

Electromagnetic transitions between two mesons containing different masses of heavy quarks using BS framework

In this paper, we calculate the electromagnetic (EM) transition decay widths between two mesons containing different heavy quarks (c and b) for the process; [Formula: see text], using the Bethe–Salpeter (BS) framework. The calculated results are found to be in a reasonable agreement with other theoretical models but the experimental data for this problem is not yet available.

New results on the decay spectroscopy of 254No with GABRIELA@SHELS

The structure of the nucleus has been studied for more than 20 years: the last publications on its decay spectroscopy are from LBNL [1], GSI [2], JYFL [3] and ANL [4]. Four decay schemes featuring two isomers have been published and are interpreted differently in terms of excitation energy and decay scheme of the 2 nd isomer and configuration assignments of both K-isomers. These discrepancies have triggered new experiments including this one, performed with the GABRIELA [5, 6] array, at the focal plane of the SHELS [7] separator at the FLNR, Dubna. The first part of this proceeding will present the experimental setup and the analysis techniques used to reveal the electromagnetic decay of the known isomers in 254No. The second part will focus on the new results obtained with more than 1 million 254No nuclei implanted in the focal plane detector. In particular, the internal conversion electron spectrum observed in the decay of the 8− K-isomer has revealed the presence of a strong transition, most likely E0, suggesting low-lying shape coexistence in this nucleus as predicted in [8, 9]. The γ-ray spectrum obtained from the decay of the short-lived 170 μs isomer has revealed new γ-ray lines putting in doubt the previous interpretations about this isomer decay.

Search for Weak Side Branches in the Electromagnetic Decay Paths of the 6526-keV 10+ Isomer in 54Fe

High-spin nuclear isomers in N≈Z nuclei between doubly magic 40Ca and 56Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV 10+ isomer in 54Fe. The isomer was strongly populated by means of the fusion-evaporation reaction 24Mg(36Ar,α2p)54mFe. The Gammasphere array was used to detect γ-ray cascades emitted from the isomeric state. By means of γγγ coincidences, weak non-yrast decay branches can be discriminated, with the isomer’s half-life confirmed at T1/2=363(4) ns. The yrast 61+→21+ E4 cross-over transition was interrogated. The observations are compared with shell-model calculations.

AGATA: Nuclear structure advancements with high-energy gamma rays

High-energy gamma rays are emitted either in the decay of nuclear discrete states (generally located in the proximity of the particle-emission threshold) or in the electromagnetic decay of collective states. The branching ratio is rather small, therefore in alternative/coincidence with high-energy gamma rays one could have neutron or charged-particle emission. The precise measurement of these branching ratios allows a more comprehensive description of the nucleus and, in particular, the selection of the nuclear models which better describes the interplay between the different acting forces and couplings. In the case of the electromagnetic decay of collective states, the precise identification of the populated low-lying states allows the measurement of their wave-function and/or of their ‘bulk’ properties. This information provides, also in this case, a stringent test for the nuclear models. In both cases, to compensate these small branching ratio, a large number of detectors and an accurate selection of a small region of the phase space are needed. AGATA is considered to constitute an optimal array for this kind of measurements. In fact, AGATA, because of its high granularity and its excellent energy resolution, can detect the high-energy gamma rays emitted in a specific decay path or associated to specific reaction channels, shapes, deformations. In the introduction, some details on the measurement of high-energy gamma rays using HPGe detector are discussed. The sections of this paper focus on the measurements of high-energy gamma rays to obtain the photon strength function, the nuclear level density and to identify extreme shapes in highly excited nuclei.

Unveiling the structural, optical, and electromagnetic attenuation characteristics of B2O3–SiO2–CaO–Bi2O3 glasses with varied WO3 content

This study provides insight into B2O3–SiO2–CaO–Bi2O3 glasses where novel results for the effects of WO3 content on its structural and optical properties have been demonstrated. Thus, provides useful data for developing new glasses for optical and electromagnetic shielding applications. The effect of WO3 content on the structural and optical properties of B2O3–SiO2–CaO–Bi2O3 glasses was investigated along with radiation shielding features which have been calculated by XCOM program. BSCB/W-00, BSCB/W-2.5, BSCB/W-5.0, BSCB/W-7.5, BSCB/W-10, BSCB/W-15, and BSCB/W-20 refer to seven samples of bismuth borosilicate glass system doped with 0.0, 2.5, 5, 7.5, 10, 15, and 20% of WO3, respectively, synthesized using the melt quenching technique. The density of the glasses decreased with increasing WO3 content due to the replacement of Bi2O3 with lower-density WO3. It was found that the absorption coefficient decreased with increasing WO3 content up to 10 wt%, but showed an opposite trend for samples with higher WO3 content. The optical band gap and the transition type were affected as the WO3 content increased. The electromagnetic wave decay or skin depth was also calculated. Overall, the shielding effectiveness of investigated samples BSCB/W-00, BSCB/W-2.5, BSCB/W-5.0, BSCB/W-7.5, BSCB/W-10, BSCB/W-15, and BSCB/W-20 has reduced with the enlargement of the WO3 concentration. BSCB/W-00, out of all the samples tested, has the highest shielding efficiency.

Decay properties of as a conventional meson* *Supported in part by the National Natural Science Foundation of China (12075073, 11865001); the Natural Science Foundation of Hebei Province, China (A2021201009); and Post-graduate's Innovation Fund Project of Hebei University (HBU2022BS002)

Taking as a conventional meson, we calculate its dominant strong and electromagnetic decays in the framework of the Bethe-Salpeter method. Our results are keV and keV. The contributions of the different partial waves from the initial and final state wave functions to the decay width are also calculated, and we find that the relativistic corrections in both decay processes are very large.

Photon strength functions, level densities, and isomeric ratio in Er168 from the radiative neutron capture measured at the DANCE facility

Background: The statistical approach is usually applied for the description of electromagnetic decay of the nucleus with the exception of the lowest excitation energies as well as for the calculation of the interaction of photons with nuclei, in particular the reaction cross sections. This concept employs nuclear level density (NLD) and photon strength functions (PSFs).Purpose: While PSFs and NLD of some well-deformed rare-earth nuclei were measured by several methods, sometimes with conflicting results, the PSFs of $^{168}\mathrm{Er}$ were addressed only by $(\ensuremath{\gamma},{\ensuremath{\gamma}}^{\ensuremath{'}})$ experiments. On the other hand, the low-lying levels of $^{168}\mathrm{Er}$ are well studied, including the isomeric state at 1094 keV, which enables various tests of the statistical approach.Methods: The $\ensuremath{\gamma}$ rays following radiative neutron capture on a $^{167}\mathrm{Er}$ sample were measured with the highly segmented $\ensuremath{\gamma}$-ray calorimeter Detector for Advanced Neutron Capture Experiments at the Los Alamos Neutron Science Center. The $\ensuremath{\gamma}$-ray energy spectra for different multiplicities (multistep cascade, or MSC, spectra) were gathered for many $s$-wave resonances of both possible spins. Moreover, we were able to detect the decay of the short-lived isomer and deduce the isomeric ratio for a few resonances.Results: Analysis of the MSC spectra within the statistical model enabled us to draw conclusions about dipole PSFs, in particular on the properties of the scissors mode, and NLD. The spectra can be well reproduced with phenomenological PSFs models but not with any of several models based on quasiparticle random-phase approximation (QRPA) calculations with different interactions. We showed that nonstatistical effects in feeding of the isomeric state play a role up to excitation energies of at least about 2 MeV.Conclusions: Deduced parameters of the scissors mode were found to be similar to those of neighbor well-deformed even-even Gd and Dy nuclei. Models like that of Kadmenskij, Markushev, and Furman (KMF) or like the modified generalized Lorentzian (MGLO) model provide a good description of experimental spectra. In contrast to several previous analyses of well-deformed rare-earth isotopes, we were able to match the experimental isomeric ratio with statistical model simulations.

χc1(2p): an overshadowed charmoniumlike resonance

A thorough study of the JPC = 1++ elastic {D}^0{overline{D}}^{ast 0} and D+D∗− scattering, where the form of the meson-meson interaction is inferred from lattice QCD calculations of string breaking, is carried out for center-of-mass energies up to 4 GeV. We show that the presence of χc1(3872), which can be naturally assigned to either a bound or virtual charmoniumlike state close below the {D}^0{overline{D}}^{ast 0} threshold, can overshadow a quasiconventional charmoniumlike resonance lying above threshold. This makes difficult the experimental detection of this resonance through the {D}^0{overline{D}}^{ast 0} and D+D∗− channels, despite being its expected main decay modes. We analyze alternative strong and electromagnetic decay modes. Comparison with existing data shows that this resonance may have already been observed through its decay to ωJ/ψ.