Archana Dixit, Saurabh Verma, Anirudh Pradhan
et al.
In this study, we explored the cosmological implications of the modified gravity framework <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><msub><mi>L</mi><mi>m</mi></msub><mo>)</mo></mrow></semantics></math></inline-formula>, taking the specific form <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><msub><mi>L</mi><mi>m</mi></msub><mo>)</mo></mrow><mo>=</mo><mstyle scriptlevel="0" displaystyle="false"><mfrac><mi>R</mi><mn>2</mn></mfrac></mstyle><mo>+</mo><msubsup><mi>L</mi><mi>m</mi><mi>n</mi></msubsup><mo>,</mo></mrow></semantics></math></inline-formula> where <i>n</i> denotes the model parameter. The analysis was carried out within a spatially flat FLRW background by adopting the Barboza–Alcaniz (BA) parametrization for the dark energy equation of state, expressed as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>ω</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow><mo>=</mo><msub><mi>w</mi><mn>0</mn></msub><mo>+</mo><msub><mi>w</mi><mn>1</mn></msub><mstyle scriptlevel="0" displaystyle="false"><mfrac><mrow><mi>z</mi><mo>(</mo><mn>1</mn><mo>+</mo><mi>z</mi><mo>)</mo></mrow><mrow><mn>1</mn><mo>+</mo><msup><mi>z</mi><mn>2</mn></msup></mrow></mfrac></mstyle><mo>.</mo></mrow></semantics></math></inline-formula> Based on this setup, an expression for the Hubble parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>H</mi><mo>(</mo><mi>z</mi><mo>)</mo></mrow></semantics></math></inline-formula> was derived. The parameters <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><msub><mi>H</mi><mn>0</mn></msub><mo>,</mo><mi>n</mi><mo>,</mo><msub><mi>w</mi><mn>0</mn></msub><mo>,</mo><msub><mi>w</mi><mn>1</mn></msub><mo>)</mo></mrow></semantics></math></inline-formula> were estimated using a Bayesian Markov Chain Monte Carlo (MCMC) technique, implemented via the <i>emcee</i> package, with Cosmic Chronometers (CC), Pantheon Plus & SH0ES (PPS) and DESI BAO datasets. For the CC+PPS+DESI BAO combination, the best-fit Hubble constant was obtained as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>H</mi><mn>0</mn></msub><mo>=</mo><msubsup><mn>72.08</mn><mrow><mo>−</mo><mn>0.24</mn></mrow><mrow><mo>+</mo><mn>0.30</mn></mrow></msubsup><mspace width="0.166667em"></mspace><mi>km</mi><mspace width="0.166667em"></mspace><msup><mi mathvariant="normal">s</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup><mspace width="0.166667em"></mspace><msup><mi>Mpc</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>,</mo></mrow></semantics></math></inline-formula> which shows better consistency with the local SH0ES measurement than with the Planck <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>Λ</mo></semantics></math></inline-formula>CDM result, thereby reducing the Hubble tension. Furthermore, the dynamical evolution of the equation of state parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ω</mi></semantics></math></inline-formula>, the deceleration parameter, the impact of various energy conditions, and the optimal model parameters were thoroughly examined. The study also investigated the behavior of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><msub><mi>O</mi><mi>m</mi></msub><mo>)</mo></mrow></semantics></math></inline-formula> diagnostic and determined the present age of the universe predicted by this model.
Abstract In 2022, the Event Horizon Telescope (EHT) collaboration has reported the first observations of Sagittarius A*(SgrA*). Applying the EHT observational results, we find out constraints on non-singular Hayward parameter of regular dark energy black hole. Considering these constraints and different thin disk accretion, we present a detailed investigation into influence of different dark energy and Hayward parameters on shadows from non-singular Hayward black holes. In the first second-order attenuation function model, corresponding shadow radius and peak for observed intensity from direct image decrease with increasing dark energy parameter and Hayward parameter. However, for the lensing ring and photon ring, corresponding peak become bigger as dark energy parameter increase in case of fixed Hayward parameter. In the second third-order attenuation function model, significantly different from model 1, above two rings completely overlay on the direct image, resulting in two distinct peaks in the observed intensity. As increase of Hayward and dark energy parameters, the difference between the two peaks decreases, and shadows and observed intensity decrease. In the final inverse trigonometric function attenuation model, the result shows corresponding lensing ring as well as photon ring can be distinguished within the superposition region, and the superposition region becomes larger. With the increase of the dark energy parameter, the shadow radius exhibits a decreasing trend, while observed intensity increases. However, with the increase of the Hayward parameter, both decreases. Compared with the first two models, the shadow radius becomes smaller, but the observed intensity becomes larger, making the bright ring wider and brighter. Therefore, different accretion models and non-singular Hayward parameters can give rise to interesting and distinguish characteristic for the black hole shadow and rings.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
The CMS collaboration, A. Hayrapetyan, A. Tumasyan
et al.
Abstract Measurements of inclusive and normalized differential cross sections of the associated production of top quark-antiquark and bottom quark-antiquark pairs, t t ¯ b b ¯ $$ \textrm{t}\overline{\textrm{t}}\textrm{b}\overline{\textrm{b}} $$ , are presented. The results are based on data from proton-proton collisions collected by the CMS detector at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb −1. The cross sections are measured in the lepton+jets decay channel of the top quark pair, using events containing exactly one isolated electron or muon and at least five jets. Measurements are made in four fiducial phase space regions, targeting different aspects of the t t ¯ b b ¯ $$ \textrm{t}\overline{\textrm{t}}\textrm{b}\overline{\textrm{b}} $$ process. Distributions are unfolded to the particle level through maximum likelihood fits, and compared with predictions from several event generators. The inclusive cross section measurements of this process in the fiducial phase space regions are the most precise to date. In most cases, the measured inclusive cross sections exceed the predictions with the chosen generator settings. The only exception is when using a particular choice of dynamic renormalization scale, μ R = 1 2 ∏ i = t , t ¯ , b , b ¯ m T , i 1 / 4 $$ {\mu}_{\textrm{R}}=\frac{1}{2}{\prod}_{i=\textrm{t},\overline{\textrm{t}},\textrm{b},\overline{\textrm{b}}}{m}_{\textrm{T},i}^{1/4} $$ , where m T , i 2 = m i 2 + p T , i 2 $$ {m}_{\textrm{T},i}^2={m}_i^2+{p}_{\textrm{T},i}^2 $$ are the transverse masses of top and bottom quarks. The differential cross sections show varying degrees of compatibility with the theoretical predictions, and none of the tested generators with the chosen settings simultaneously describe all the measured distributions.
Nuclear and particle physics. Atomic energy. Radioactivity
The paper presents the original observation of high frequency Alfvén eigenmode excited by fast minority hydrogen ions accelerated by ion cyclotron range of frequency waves in EAST. The frequency of high frequency Alfvén eigenmodes is around $0.75\sim 0.8 * \Omega_H$ , where $\Omega_H$ is the cyclotron frequency of hydrogen ions evaluated at the low-field side plasma edge. It tracks the on-axis magnetic field B _t and the edge plasma electron density n _e via the Alfvénic relation $\omega\sim B_t*{n_e}^{-1/2}$ . The high frequency Alfvén eigenmodes are always accompanied by sub-cyclotron modes in several experiments at EAST, consistent with the high frequency Alfvén eigenmode detected on other conventional tokamaks, namely ASDEX Upgrade and DIII-D. Based on the previous study, these sub-cyclotron modes are consistent with the spectrum splitting produced by toroidal mode numbers (Gorelenkov et al 2003 Nucl. Fusion 43 228). We also found that the location of eigenmode excitation of high frequency Alfvén eigenmode driven by RF-accelerated minority hydrogen ions remains unchanged even though the cyclotron resonance location of hydrogen ions varies with B _t .
Nuclear and particle physics. Atomic energy. Radioactivity
For well over half a century, precision studies of neutron and nuclear $β$ decays have been at the forefront of searches for exotic electroweak physics. Recent advances in nuclear ab initio theory and the widespread use of effective field theories means that its modern understanding is going through a transitional phase. This has been propelled by current tensions in the global data set leading to renewed scrutiny of its theoretical ingredients. In parallel, a host of novel techniques and methods are being investigated that are able to sidestep many traditional systematic uncertainties and require a diverse palette of skills and collaboration with material science and condensed matter physics. We highlight the current opportunities and open questions with the aim of facilitating the transition to a more modern understanding of $β$ decay.
Anita M. D'Angelo, Helen E. A. Brand, Valerie D. Mitchell
et al.
This study describes the capabilities and limitations of carrying out total scattering experiments on the Powder Diffraction (PD) beamline at the Australian Synchrotron, ANSTO. A maximum instrument momentum transfer of 19 Å−1 can be achieved if the data are collected at 21 keV. The results detail how the pair distribution function (PDF) is affected by Qmax, absorption and counting time duration at the PD beamline, and refined structural parameters exemplify how the PDF is affected by these parameters. There are considerations when performing total scattering experiments at the PD beamline, including (1) samples need to be stable during data collection, (2) highly absorbing samples with a μR > 1 always require dilution and (3) only correlation length differences >0.35 Å may be resolved. A case study comparing the PDF atom–atom correlation lengths with EXAFS-derived radial distances of Ni and Pt nanocrystals is also presented, which shows good agreement between the two techniques. The results here can be used as a guide for researchers considering total scattering experiments at the PD beamline or similarly setup beamlines.
Nuclear and particle physics. Atomic energy. Radioactivity, Crystallography
Manoj K. Mandal, Pierpaolo Mastrolia, Hector O. Silva
et al.
Abstract We present a gravitoelectric quadrupolar dynamical tidal-interaction Hamiltonian for a compact binary system, that is valid to second order in the post-Newtonian expansion. Our derivation uses the diagrammatic effective field theory approach, and involves Feynman integrals up to two loops, evaluated with the dimensional regularization scheme. We also derive the effective Hamiltonian for adiabatic tides, obtained by taking the appropriate limit of the dynamical effective Hamiltonian, and we check its validity by verifying the complete Poincaré algebra. In the adiabatic limit, we also calculate two gauge-invariant observables, namely, the binding energy for a circular orbit and the scattering angle in a hyperbolic scattering. Our results are important for developing accurate gravitational waveform models for neutron-star binaries for present and future gravitational-wave observatories.
Nuclear and particle physics. Atomic energy. Radioactivity
The elliptic flow (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>v</mi><mn>2</mn></msub></semantics></math></inline-formula>) of produced particles is one of the important observables sensitive to the transport properties of the strongly interacting matter created in relativistic heavy-ion collisions. Detailed differential measurements of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>v</mi><mn>2</mn></msub></semantics></math></inline-formula> are also foreseen in the future Multi-Purpose Detector (MPD) experiment at the Nuclotron based Ion Collider fAcility (NICA) at collision energies <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt></semantics></math></inline-formula> = 4–11 GeV. Elliptic flow strongly depends on collision geometry, defined by the impact parameter <i>b</i>. Usually <i>b</i> is an input to theoretical calculations and can be deduced from experimental observables in the final state using the centrality procedure. In this work, we investigate the influence of the choice of centrality procedure on the elliptic flow measurements at NICA energies.
Nuclear and particle physics. Atomic energy. Radioactivity
We study the transverse momentum ($p_T$) spectra of neutral pions and identified charged hadrons produced in proton--proton ($pp$), deuteron--gold ($d$--Au), and gold--gold (Au--Au) collisions at the center of mass energy $\sqrt{s_{NN}}=200$ GeV. The study is made in the framework of a multi-source thermal model used in the partonic level. It is assumed that the contribution to the $p_T$-value of any hadron comes from two or three partons with an isotropic distribution of the azimuthal angle. The contribution of each parton to the $p_T$-value of a given hadron is assumed to obey any one of the standard (Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein) distributions with the kinetic freeze-out temperature and average transverse flow velocity. The $p_T$-spectra of the final-state hadrons can be fitted by the superposition of two or three components. The results obtained from our Monte Carlo method are used to fit the experimental results of the PHENIX and STAR Collaborations. The results of present work serve as a suitable reference baseline for other experiments and simulation studies.
Abstract The removal of aerosol particles and vapors in gas bubbles moving through a water pool is known to be an efficient means to reduce source term to the environment during severe accidents, as happened in Fukushima Daiichi. This trapping, called pool scrubbing, entails a complex phenomenology in which hydrodynamics, thermal hydraulics, and aerosol physics strongly affect each other and determine the net transfer of radioactivity coming out from the aqueous pond. More than 20 experimental programs have addressed this issue since the early 1980s, but few of them did it in a systematic and representative way. This paper thoroughly reviews the entire pool scrubbing database until 2016 and assesses the adequacy of the experimental setup, representativeness of boundary conditions, weaknesses in decontamination factor derivation, data uncertainties, and some other aspects to finally synthesize a reduced number of experiments that could be used as an experimental matrix for the validation of pool scrubbing models. More than 500 tests were reviewed and classified as Qualified for Validation, Useful for Understanding, or Not Useful; less than 15% of these experiments are considered in the proposed validation matrix due to different reasons. Major insights and remaining needs are also highlighted. This work was conducted under the framework of the Integration of Pool Scrubbing Research to Enhance Source-Term Calculations, or the IPRESCA project, led by Becker Technologies, in the framework of the Sustainable Nuclear Energy Technology Platform/Nuclear Generation II & III Alliance/Technical Area 2.
The role David Rowe played in advancing our understanding of nuclear structure has been pivotal to modernizing the theory into one that does not require the use of an effective charge concept, and one that is extensible across the chart of the nuclides. We briefly review how this flows from the early history of the field, focusing especially on David’s role in helping to bridge the divide between single-particle models and collective models of nuclear structure, and how this has led to the development of a beautiful and bold algebraic framework that underpins a theory of choice for future nuclear structure studies. Looking forward, David Rowe’s work also underpins current follow-on efforts focused on paving the way for the construction of yet another bridge, one that should help to span the chasm between low-energy and high-energy nuclear physics. If successful, the latter could ultimately lead to a truly ab initio framework for gaining a far broader understanding of nuclear structure, one that tracks forward from the fundamental structure of hadrons, especially protons and neutrons, and how they in turn conspire to give us atomic nuclei that in reality are the building blocks of the universe in which we live.
The extraordinary performance offered by cold atom-based clocks and sensors has the opportunity to profoundly affect a range of applications, for example in gravity surveys, enabling long term monitoring applications through low drift measurements. While ground-based devices are already starting to enter the commercial market, significant improvements in robustness and reductions to size, weight, and power are required for such devices to be deployed by Unstaffed Aerial Vehicle systems (UAV). In this article, we realise the first step towards the deployment of cold atom based clocks and sensors on UAV’s by demonstrating an UAV portable magneto-optical trap system, the core package of cold atom based systems. This system is able to generate clouds of <inline-formula><math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>2.1</mn><mo>±</mo><mn>0.2</mn><mo>×</mo><msup><mn>10</mn><mn>7</mn></msup></mrow></semantics></math></inline-formula> atoms, in a package of 370 mm × 350 mm × 100 mm, weighing 6.56 kg, consuming 80 W of power.
Nuclear and particle physics. Atomic energy. Radioactivity
Recent MHD simulations find that the reversal of the local resistive interchange parameter $D_\mathrm{R}$ from negative to positive due to impurity radiation cooling is able to linearly destabilize the resistive tearing mode (TM) growth in a tokamak above a threshold in impurity level. A layer of perturbed Pfirsch–Schlüter current density and resistivity are also induced by the impurity radiation, which further govern the TM growth and saturation in the nonlinear stage. The impurity threshold and the TM growth strongly depend on the parallel thermal conductivity, and such a dependence derives from the impact on $D_\mathrm{R}$ of the fast parallel thermal equilibration along the helical magnetic field lines.
Nuclear and particle physics. Atomic energy. Radioactivity
Uranium dioxied is used as a nuclear fuel. Depending on the temperature and
oxygen partial pressure, it is incredibly versatile and can accept a wide
variety of stoichiometry. Many methods are used to estimate the
non-stoichiometric O/U ratio such as the coulometric titration, gravimetric
and voltammetric methods. These methods have some disadvantages and may be
time and cost-consuming. This work develops an approach to determine the
stoichiometric ratio by using MCNP-5 code and hyper pure germanium detector
to estimate the count rate at 185.7 keV for UO2 pellets. The studied
pellets are proposed to have 235U mass content (3 %, 4 %, and 5 %) and 1 cm
away from the detector. The mass of the oxide within the pellets is 7.8995
grams. The relation between volume and density has been studied during
different steps in which temperature increases. Finally, a reliable model is
established to describe the process of converting green pellets to sintered
pellets. The model is supported by employing artificial intelligence to
predict some features and the overall correlation equals 0.99929.
Nuclear and particle physics. Atomic energy. Radioactivity
Electron Ion Collider (EIC) is a particle accelerator facility planned for construction at Brookhaven National Laboratory on Long Island, New York by the United States Department of Energy. EIC will provide capabilities of colliding beams of polarized electrons with polarized beams of proton and light ions. EIC will be one of the largest and most sophisticated new accelerator facilities worldwide, and the only new large-scale accelerator facility planned for construction in the United States in the next few decades. The versatility, resolving power and intensity of EIC will present many new opportunities to address some of the crucial and fundamental open scientific questions in particle physics. This document provides an overview of the science case of EIC from the perspective of the high energy physics community.