Hasil untuk "Nuclear and particle physics. Atomic energy. Radioactivity"

A. Triantafyllidis, J.-R. Marquès, S. Ferri et al.

We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced, magnetized plasma (1–3 × 1018 cm−3, 1–15 eV) in the context of a laboratory astrophysics experiment under a controlled magnetic field up to 20 T. Nitrogen lines (NII) in the visible range (563–574 nm) were used to diagnose the magnetic field and plasma conditions. This was performed by coupling our data with the Stark–Zeeman line-shape code PPPB. The excellent agreement between experiment and simulations paves the way for a non-intrusive experimental platform to get time-resolved measurements of the local magnetic field in laboratory plasmas.

Aviv Padawer-Blatt, Zhiwei Shao, Renier T. Hough et al.

We employ the <span style="font-variant: small-caps;">simba-c</span> cosmological simulation to study the impact of its upgraded chemical enrichment model (Chem5) on the distribution of metals in the intragroup medium (IGrM). We investigate the projected X-ray emission-weighted abundance profiles of key elements over two decades in halo mass (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mn>10</mn><mn>13</mn></msup><mo>≤</mo><msub><mi>M</mi><mn>500</mn></msub><mo>/</mo><msub><mi mathvariant="normal">M</mi><mo>⊙</mo></msub><mo>≤</mo><msup><mn>10</mn><mn>15</mn></msup></mrow></semantics></math></inline-formula>). Typically, <span style="font-variant: small-caps;">simba-c</span> generates lower-amplitude abundance profiles than <span style="font-variant: small-caps;">simba</span> with flatter cores, in better agreement with observations. For low-mass groups, both simulations over-enrich the IGrM with Si, S, Ca, and Fe compared to observations, a trend likely related to inadequate modeling of metal dispersal and mixing. We analyze the 3D mass-weighted abundance profiles, concluding that the lower <span style="font-variant: small-caps;">simba-c</span> IGrM abundances are primarily a consequence of fewer metals in the IGrM, driven by reduced metal yields in Chem5, and the removal of the instantaneous recycling of metals approximation employed by <span style="font-variant: small-caps;">simba</span>. Additionally, an increased IGrM mass in low-mass <span style="font-variant: small-caps;">simba-c</span> groups is likely triggered by changes to the AGN and stellar feedback models. Our study suggests that a more realistic chemical enrichment model broadly improves agreement with observations, but physically motivated sub-grid models for other key processes, like AGN and stellar feedback and turbulent diffusion, are required to realistically reproduce observed group environments.

P. Potts

Noam Soker

In comparing the two alternative explosion mechanisms of core-collapse supernovae (CCSNe), I examine recent three-dimensional (3D) hydrodynamical simulations of CCSNe in the frame of the delayed neutrino explosion mechanism (neutrino mechanism) and argue that these valuable simulations show that neutrino heating can supply a non-negligible fraction of the explosion energy but not the observed energies, and hence cannot be the primary explosion mechanism. In addition to the energy crisis, the neutrino mechanism predicts many failed supernovae that are not observed. The most challenging issue of the neutrino mechanism is that it cannot account for point-symmetric morphologies of CCSN remnants, many of which were identified in 2024. These contradictions with observations imply that the neutrino mechanism cannot be the primary explosion mechanism of CCSNe. The alternative jittering jets explosion mechanism (JJEM) seems to be the primary explosion mechanism of CCSNe; neutrino heating boosts the energy of the jittering jets. Even if some simulations show explosions of stellar models (but usually with energies below that observed), it does not mean that the neutrino mechanism is the explosion mechanism. Jittering jets, which simulations do not include, can explode the core before the neutrino heating process does. Morphological signatures of jets in many CCSN remnants suggest that jittering jets are the primary driving mechanism, as expected by the JJEM.

Alexander Belavin, Sergej Parkhomenko

In Gepner's pioneering work, the requirement that leads to a model having the desired N=1 Spacetime supersymmetry and E(8)×E(6) Gauge symmetry was the requirement that the spacetime symmetry is compatible with modular invariance. In this work we show that the requirement for the simultaneous fulfillment of mutual locality of the left-moving vertices of physical states with the space-time symmetry generators and of right-moving vertices with generators of E(8)×E(6)-gauge symmetry, which arises after some special reduction together with the requirement of mutual locality of complete (left-right) vertices of physical states among themselves leads to the same Gepner models.

Cyuan-Han Chang, David Simmons-Duffin

Abstract We study the three-point energy correlator (EEEC), defined as a matrix element of a product of three energy detectors at different locations on the celestial sphere. Lorentz symmetry implies that the EEEC can be decomposed into special functions called celestial blocks. We compute three-point celestial blocks in an expansion around the collinear limit, where the three detectors approach each other on the celestial sphere. The leading term is a traditional d – 2-dimensional four-point conformal block, and thus the collinear EEEC behaves like a conformally-invariant four-point function in d – 2 dimensions. We obtain the coefficients of the conformal block decomposition for the collinear EEEC at leading nontrivial order in weakly-coupled 𝒩 = 4 SYM and QCD. These data allow us to make certain all-orders predictions for the collinear EEEC in various kinematic limits, including the OPE limit and the double lightcone limit. We also study Ward identities satisfied by the EEEC and compute contact terms in the EEEC in weakly-coupled 𝒩 = 4 SYM. Finally, we study the celestial block expansion of the EEEC in planar 𝒩 = 4 SYM at strong coupling, determining celestial block coefficients to leading and first subleading order at large λ.

Ed Bennett, Jack Holligan, Deog Ki Hong et al.

We review the current status of the long-term programme of numerical investigation of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>p</mi><mo>(</mo><mn>2</mn><mi>N</mi><mo>)</mo></mrow></semantics></math></inline-formula> gauge theories with and without fermionic matter content. We start by introducing the phenomenological as well as theoretical motivations for this research programme, which are related to composite Higgs models, models of partial top compositeness, dark matter models, and in general to the physics of strongly coupled theories and their approach to the large-<i>N</i> limit. We summarise the results of lattice studies conducted so far in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>p</mi><mo>(</mo><mn>2</mn><mi>N</mi><mo>)</mo></mrow></semantics></math></inline-formula> Yang–Mills theories, measuring the string tension, the mass spectrum of glueballs and the topological susceptibility, and discuss their large-<i>N</i> extrapolation. We then focus our discussion on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>p</mi><mo>(</mo><mn>4</mn><mo>)</mo></mrow></semantics></math></inline-formula>, and summarise the numerical measurements of mass and decay constant of mesons in the theories with fermion matter in either the fundamental or the antisymmetric representation, first in the quenched approximation, and then with dynamical fermions. We finally discuss the case of dynamical fermions in mixed representations, and exotic composite fermion states such as the chimera baryons. We conclude by sketching the future stages of the programme. We also describe our approach to open access.

А.М. Кабдулинов, Б.Р. Нусупбеков, А.К. Хасенов et al.

This article is dedicated to technologies research that require development and implementation in Kazakhstan, able to provide energy sources economy, as well as improvement of sanitary-hygiene and economical indexes of production. But it’s hard to achieve it, if there is no special equipment at enterprises for achieving of this aim. Therefore, the main aim is to design schemes for automated control system and management for technological process for providing of safety and effective functioning of enterprise. To accomplish this goal, we will describe the mathematical model of the regulatory object, as well as investigate the system of automatic regulation for stability. To analyze the relationship between the defining parameters of the cupola process using advanced experience in operating cupola, the latest achievements in the field of mathematical modeling of technical systems and modern computer technology, considering the process as a cybernetic system.The structure of the management system is developed in accordance with the main trends in automation identified during the analytical review.

Vasileios A. Letsios

Abstract We present the dictionary between the one-particle Hilbert spaces of totally symmetric tensor-spinor fields of spin s = 3/2, 5/2 with any mass parameter on D-dimensional (D ≥ 3) de Sitter space (dS D ) and Unitary Irreducible Representations (UIR’s) of the de Sitter algebra spin(D, 1). Our approach is based on expressing the eigenmodes on global dS D in terms of eigenmodes of the Dirac operator on the (D − 1)-sphere, which provides a natural way to identify the corresponding representations with known UIR’s under the decomposition spin(D, 1) ⊃ spin(D). Remarkably, we find that four- dimensional de Sitter space plays a distinguished role in the case of the gauge-invariant theories. In particular, the strictly massless spin-3/2 field, as well as the strictly and partially massless spin-5/2 fields on dS D , are not unitary unless D = 4.

Remigiusz Durka, Jerzy Kowalski-Glikman

Abstract We consider two BF formulations of the theory of gravity with a negative cosmological constant, of Plebanski and of MacDowell-Mansouri. Both give the standard Einstein equations in the bulk but differ in expressions of edge charges. We compute the asymptotic charges explicitly in both theories for AdS-Schwarzschild, AdS-Kerr, and AdS-Taub-NUT solutions. We find that while in the case of the Plebanski theory the charges are divergent, they are finite for MacDowell-Mansouri theory. Furthermore, we show that in the case of the arbitrary asymptotically AdS spacetimes, MacDowell-Mansouri asymptotic charges, action, and symplectic form are all finite. Therefore MacDowell-Mansouri theory of gravity in asymptotically AdS spaces does not need any counterterms.

WANG Dongmei, WANG Bin, MA Xiangmei et al.

Polyvinyl chloride (PVC), which is used as one of the most widely polymer, the general purpose plastic in industry, agriculture, household items and many other fields because of abrasion resistance, thermal insulation, and low cost, etc. Nevertheless, PVC can easily change color, degrade under heating or ultraviolet (UV) light radiation because of its structural features and inherent composition, finally limited the application range of the materialist. To overcome these, the zinc- copper -sulphur composite was prepared with ZnO nanoparticle, copper chloride, thiourea and thiophene, then added to PVC solution, composite films were prepared by a casting method. Transmission electron microscopy (TEM), X-ray powder diffraction spectra (XRD), Fourier transform infrared (FTIR) and ultraviolet (UV) spectrophotometr were applied to study the structure and optical performance. The results showed that the functionalized ZnO NPs could endow the PVC composite films with excellent UV shielding capability.

Vlad-Mihai Mandric, Tim R. Morris, Dalius Stulga

Abstract We investigate off-shell perturbative renormalisation of pure quantum gravity for both background metric and quantum fluctuations. We show that at each new loop order, the divergences that do not vanish on-shell are constructed from only the total metric, whilst those that vanish on-shell are renormalised by canonical transformations involving the quantum fields. Purely background metric divergences do not separately appear, and the background metric does not get renormalised. We highlight that renormalisation group identities play a crucial rôle ensuring consistency in the renormalisation of BRST transformations beyond one loop order. We verify these assertions by computing leading off- shell divergences to two loops, exploiting off-shell BRST invariance and the renormalisation group equations. Although some divergences can be absorbed by field redefinitions, we explain why this does not lead to finite beta-functions for the corresponding field.

Z. P. Li, D. Vretenar

Collective motion is a manifestation of emergent phenomena in mediumheavy and heavy nuclei. A relatively large number of constituent nucleons contribute coherently to nuclear excitations (vibrations, rotations) that are characterized by large electromagnetic moments and transition rates. Basic features of collective excitations are reviewed, and a simple model introduced that describes large-amplitude quadrupole and octupole shape dynamics, as well as the dynamics of induced fission. Modern implementations of the collective Hamiltonian model are based on the microscopic framework of energy density functionals, that provide an accurate global description of nuclear ground states and collective excitations. Results of illustrative calculations are discussed in comparison with available data. Outline • Introduction • Nuclear Shape Parameters • Nuclear Surface Oscillations • The Rotation-Vibration Model • Microscopic Derivation of the Collective Hamiltonian • Microscopic Collective Hamiltonian Based on Density Functional Theory Z. P. Li School of Physical Science and Technology, Southwest University, Chongqing 400715, China, email: zpliphy@swu.edu.cn D. Vretenar Department of Physics, Faculty of Science, University of Zagreb, HR-10000 Zagreb, Croatia; State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China, e-mail: vretenar@phy.hr ∗ zpliphy@swu.edu.cn 1 ar X iv :2 20 3. 07 60 8v 1 [ nu cl -t h] 1 5 M ar 2 02 2 2 Z. P. Li and D. Vretenar Introduction A medium-heavy or heavy atomic nucleus presents a typical example of a complex quantum system, in which different interactions between a relatively large number of constituent nucleons give rise to physical phenomena that are qualitatively different from those exhibited by few-nucleon systems. There are a number of features that characterize complex systems, but for the topic of the present chapter of particular interest is the emergence of collective structures and dynamics that do not occur in light nuclei composed of only a small number of nucleons. Collective motion is the simplest manifestation of emergent phenomena in atomic nuclei. It can be interpreted as a kind of motion in which a large number of nucleons contribute coherently to produce a large amplitude oscillation of one or more electromagnetic multipole moments. Collective motion gives rise to excited states that are characterized by large electromagnetic transition rates to the ground state, that is, rates that correspond to many single-particle transitions [1]. This chapter will mainly focus on low-energy large-amplitude collective motion (LACM), such as surface vibrations, rotations, and fission. Theoretical studies of LACM started as early as in the 1930s. Based on the liquid drop model of the atomic nucleus [2], Flügge applied Rayleigh’s normal modes [3] to a classical description of low-energy excitations of spherical nuclei [4]. The model of Flügge was quantized by Bohr [5], who formulated a quantum model of surface oscillations of spherical nuclei, and also introduced the concept of intrinsic frame of reference for a quadrupole deformed nuclear surface characterized by the Euler angles and the shape parameters β and γ (nowadays often called the Bohr deformation parameters). Subsequently, Bohr and Mottelson [6] generalized the model to vibrations and rotations of deformed nuclei. A generalization of the Bohr Hamiltonian to describe large-amplitude collective quadrupole excitations of even-even nuclei of arbitrary shape was introduced by Belyaev [7] and Kumar and Baranger [8]. Several specific forms of the collective Hamiltonian, designed to describe collective excitations in nuclei of particular shape were also considered [9–14]. In the past several decades, enormous progress has been made in developing microscopic many-body theories of nuclear systems. However, a description of collective phenomena starting from single-nucleon degrees of freedom still presents a considerable challenge. One of the methods that has been used to obtain such a description is the adiabatic time-dependent HFB theory (ATDHFB) [7, 15, 16] which, in the case of quadrupole collective coordinates, leads to the Bohr Hamiltonian. Another approach to collective phenomena that is based on microscopic degrees of freedom, is the generator coordinate method (GCM) [17]. In the Gaussian overlap approximation (GOA) [18, 19], the GCM also leads to the Bohr collective Hamiltonian [20, 21]. Model for collective motion 3 Nuclear Shape Parameters Excitation spectra of even-even nuclei in the energy range of up to ≈ 3 MeV, exhibit characteristic band structures that are interpreted as vibrations and rotations of the nuclear surface in the geometric collective model, first introduced by Bohr and Mottelson [5, 6], and further elaborated by Faessler and Greiner [12, 13]. For low-energy excitations the compression mode is not relevant because of high incompressibility of nuclear matter, and the diffuseness of the nuclear surface layer can also be neglected to a good approximation. One therefore starts with the model of a nuclear liquid drop of constant density and sharp surface. With these assumptions, the time-dependent nuclear surface can, quite generally, be described by an expansion in spherical harmonics with shape parameters as coefficients: R(θ ,φ ; t) = R0 ( 1+ ∞ ∑ λ=0 λ ∑ μ=−λ αλ μ(t)Yλ μ(θ ,φ) ) (1) where R(θ ,φ ; t) denotes the nuclear radius in spherical coordinates (θ ,φ), and R0 is the radius of a sphere with the same volume. The shape parameters αλ μ(t) play the role of collective dynamical variables, and their physical meaning will be discussed for increasing values of λ . Fig. 1 Nuclear shapes with dipole (λ = 1), quadrupole (λ = 2), octupole (λ = 3), and hexadecupole (λ = 4) deformations. To lowest order, the dipole mode λ = 1 corresponds to a translation of the nucleus as a whole and, therefore, is not considered for low-energy excitations. Dynamical quadrupole deformations, that is, the mode with λ = 2, turn out to be the most relevant low-lying collective excitations. Most of the following discussion of collective models will focus on this case, so a more detailed description is included below. Octupole dynamical deformations, λ = 3, are the principal asymmetric modes of a nucleus associated with negative-parity bands. While there is no evidence for pure hexadecupole excitations in low-energy spectra, this mode plays an important role as admixture to quadrupole excitations, and for fission dynamics. Shape oscillations of higher multipoles are not relevant for low-energy excitations. For the case of pure quadrupole deformation the nuclear surface is parameterized R(θ ,φ) = R0 ( 1+ 2 ∑ μ=−2 α∗ μY2μ(θ ,φ) ) (2) 4 Z. P. Li and D. Vretenar where the time dependence is implicit for dynamical variables. If the shape of the nucleus is an ellipsoid, its three principal axes (x, y, z) are linked with the (X , Y , Z) axes of a Cartesian coordinate system in the laboratory frame. From the symmetry of the ellipsoid, it follows that a1 = a−1 = 0,a2 = a−2, where aμ are the shape parameters in the principal-axis system. Obviously, the five coefficients αμ in the laboratory frame reduce to two real independent variables a0 and a2 in the principal-axis system, which, together with the three Euler angles, provide a complete parameterization of the nuclear surface. The details of the transformation between αμ and aμ are included below. In the principal-axis system, the nuclear radius is given by R(θ ′,φ ′) = R0 [ 1+a0Y20(θ ′,φ )+a2Y22(θ ′,φ )+a2Y2−2(θ ′,φ ′) ] . (3) Two parameters (a0, a2) are generally used to describe quadrupole deformations but, instead of a0 and a2, the polar coordinates β and γ are usually employed. They are defined as follows: a0 = β cosγ, a2 = 1 √ 2 β sinγ. (4) Using Eq. (3) and Eq. (4), we can express the increments of the three semi-axes in the principal-axis system: δRκ = R0 √ 5 4π β cos ( γ− 2π 3 κ ) , κ = 1,2,3 (5) where κ = 1,2,3 correspond to x,y,z, respectively. The parameters β and γ only describe exactly ellipsoidal shapes in the limit of small β -values.

Santosh V. Lohakare, Francisco Tello-Ortiz, S. K. Tripathy et al.

In this paper, we studied the bouncing behavior of the cosmological models formulated in the background of the Hubble function in the <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><mi mathvariant="script">G</mi><mo>)</mo></mrow></semantics></math></inline-formula> theory of gravity, where <i>R</i> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="script">G</mi></semantics></math></inline-formula>, respectively, denote the Ricci scalar and Gauss–Bonnet invariant. The actions of the bouncing cosmology are studied with a consideration of the different viable models that can resolve the difficulty of singularity in standard Big Bang cosmology. Both models show bouncing behavior and satisfy the bouncing cosmological properties. Models based on dynamical, deceleration, and energy conditions indicate the accelerating behavior at the late evolution time. The phantom at the bounce epoch is analogous to quintessence behavior. Finally, we formulate the perturbed evolution equations and investigate the stability of the two bouncing solutions.

H. Alharazin, E. Epelbaum, J. Gegelia et al.

Abstract The leading one-loop corrections to the gravitational form factors of the delta resonance are calculated in the framework of chiral effective field theory. Various contributions to the energy–momentum tensor and the renormalization of the low-energy constants are worked out. Using the small scale expansion, expressions for static quantities are obtained and the real and imaginary parts of the gravitational form factors are calculated numerically.

Y. Hino, S. Ajimura, M. K. Cheoun et al.

Abstract JSNS $$^2$$ 2  (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that is searching for sterile neutrinos via the observation of $${\bar{\nu }}_{\mu } \rightarrow {\bar{\nu }}_{e}$$ ν ¯ μ → ν ¯ e  appearance oscillations using muon decay-at-rest neutrinos. Before dedicated data taking in the first-half of 2021, we performed a commissioning run for 10 days in June 2020. Using the data obtained in this commissioning run, in this paper, we present an estimate of the correlated background which imitates the $${\bar{\nu }}_{e}$$ ν ¯ e  signal in a sterile neutrino search. In addition, in order to demonstrate future prospects of the JSNS $$^2$$ 2  experiment, possible pulse shape discrimination improvements towards reducing cosmic ray induced fast neutron background are described.

Wafia Bensalem, David London, Daniel Stolarski et al.

Abstract We study the collider phenomenology of a simplified model containing a right-handed W in which the W R couples predominantly to the third generation in the quark sector. The model also includes a light Majorana neutrino, with M 1 ∼ O 100 $$ \mathcal{O}(100) $$ GeV, giving rise to lepton-number-violating signatures that are visible at the LHC. Taking into account all the searches from the LHC and Tevatron, we find that this W R can still be as light as M R ∼ 300 GeV. We show that this type of new physics, and others like it, can be detected at the LHC using final states with three same-sign same-flavour leptons.

V. Niarchos, C. Papageorgakis, A. Pini et al.

Abstract Building on [1], we uncover new properties of type-B conformal anomalies for Coulomb-branch operators in continuous families of 4D N $$ \mathcal{N} $$ = 2 SCFTs. We study a large class of such anomalies on the Higgs branch, where conformal symmetry is spontaneously broken, and compare them with their counterpart in the CFT phase. In Lagrangian the- ories, the non-perturbative matching of the anomalies can be determined with a weak coupling Feynman diagram computation involving massive multi-loop banana integrals. We extract the part corresponding to the anomalies of interest. Our calculations support the general conjecture that the Coulomb-branch type-B conformal anomalies always match on the Higgs branch when the IR Coulomb-branch chiral ring is empty. In the opposite case, there are anomalies that do not match. An intriguing implication of the mismatch is the existence of a second covariantly constant metric on the conformal manifold (other than the Zamolodchikov metric), which imposes previously unknown restrictions on its holonomy group.

C. Aalseth, S. Abdelhakim, F. Acerbi et al.

Oscar Henriksson, Carlos Hoyos, Niko Jokela

Abstract We revisit the large-N c phase diagram of N $$ \mathcal{N} $$ = 4 super Yang-Mills theory at finite R-charge density and strong coupling, by means of the AdS/CFT correspondence. We conjecture new phases that result from a black hole shedding some of its charge through the nucleation of probe color D3-branes that remain at a finite distance from the black hole when the dual field theory lives on a sphere. In the corresponding ground states the color group is partially Higgsed, so these phases can be identified as having a type of color superconductivity. The new phases would appear at intermediate values of the R-charge chemical potential and we expect them to be metastable but long-lived in the large-N c limit.