Abstract We construct integrated and unintegrated vertex operators for the type II superstring using the B-RNS-GSS formalism. The construction is done in flat spacetime background for both type II superstrings and type IIB superstring in a $$AdS_5\times S^5$$ A d S 5 × S 5 background.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Abstract In a cosmological first-order phase transition (FOPT), the true and false vacuum bubble radius distributions are not expected to be monochromatic, as is usually assumed. Consequently, Fermi balls (FBs) and primordial black holes (PBHs) produced in a dark FOPT will have extended mass distributions. We show how gravitational wave (GW), microlensing and Hawking evaporation signals for extended bubble radius/mass distributions deviate from the case of monochromatic distributions. The peak of the GW spectrum is shifted to lower frequencies, and the spectrum is broadened at frequencies below the peak frequency. Thus, the radius distribution of true vacuum bubbles introduces another uncertainty in the evaluation of the GW spectrum from a FOPT. The extragalactic gamma-ray signal at AMEGO-X/e-ASTROGAM from PBH evaporation may evince a break in the power-law spectrum between 5 MeV and 10 MeV for an extended PBH mass distribution. Optical microlensing surveys may observe PBH mass distributions with average masses below $$10^{-10}M_\odot $$ 10 - 10 M ⊙ , which is not possible for monochromatic mass distributions. This expands the FOPT parameter space that can be explored with microlensing.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Joshua Davies, Kay Schönwald, Matthias Steinhauser
et al.
Abstract We compute three-loop corrections to the process gg → HH originating from one-particle reducible diagrams. This requires the computation of two-loop corrections to the gluon-gluon-Higgs vertex with an off-shell gluon. We describe in detail our approach to obtain semi-analytic results for the vertex form factors and present results for the two form factors contributing to Higgs boson pair production.
Nuclear and particle physics. Atomic energy. Radioactivity
Melanie Nentwich, Matthias Zschornak, Tina Weigel
et al.
During X-ray diffraction experiments on single crystals, the diffracted beam intensities may be affected by multiple-beam X-ray diffraction (MBD). This effect is particularly frequent at higher X-ray energies and for larger unit cells. The appearance of this so-called Renninger effect often impairs the interpretation of diffracted intensities. This applies in particular to energy spectra analysed in resonant experiments, since during scans of the incident photon energy these conditions are necessarily met for specific X-ray energies. This effect can be addressed by carefully avoiding multiple-beam reflection conditions at a given X-ray energy and a given position in reciprocal space. However, areas which are (nearly) free of MBD are not always available. This article presents a universal concept of data acquisition and post-processing for resonant X-ray diffraction experiments. Our concept facilitates the reliable determination of kinematic (MBD-free) resonant diffraction intensities even at relatively high energies which, in turn, enables the study of higher absorption edges. This way, the applicability of resonant diffraction, e.g. to reveal the local atomic and electronic structure or chemical environment, is extended for a vast majority of crystalline materials. The potential of this approach compared with conventional data reduction is demonstrated by the measurements of the Ta L3 edge of well studied lithium tantalate LiTaO3.
Nuclear and particle physics. Atomic energy. Radioactivity, Crystallography
Abstract We perform a high-precision computation of the three-loop three-point form factor of the stress-tensor supermultiplet in N $$ \mathcal{N} $$ = 4 SYM. Both the leading-color and sub-leading-color form factors are expanded in terms of simple integrals. We compute the complete set of integrals at a special kinematic point with very high precision using AMFlow. The high-precision leading-color result enables us to obtain the analytic form of a numerical constant in the three-loop BDS ansatz, which is previously known only numerically. The high-precision values of the non-leading-color finite remainder as well as all integrals are also presented, which can be valuable for future use.
Nuclear and particle physics. Atomic energy. Radioactivity
The thermal quenching effect has not been considered in current research on the first-order kinetics of thermoluminescence. In contrast, thermal quenching as a reality should be contained in theoretical models. In this work, a new fitting function of the thermoluminescence glow curve in terms of peak temperature and intensity is obtained by considering the thermal quenching effect for the first-order kinetics model. The new function reduces to the known first-order fit function by removing thermal quenching parameters. The obtained function was applied to the glow curve of the CaF2:Mn (TLD-400) dosimeter. Since the new model differs from the known first-order fit function, different kinetic parameters extract as the result of the fitting procedure. As the new model involves the thermal quenching effect as a physical entity, the kinetic parameters obtained from the presented model are more accurate and realistic.
Nuclear and particle physics. Atomic energy. Radioactivity
Abstract The problem of the distribution of axionlike particle, being the model of dark matter, in the nearby of rotating wormholes has been investigated numerically. In the model in question the axion scalar is non-trivially coupled to the Maxwell gauge field. We consider two toy models of rotating wormholes embedded in magnetic field, Kerr-like and Teo rotating wormholes. Moreover one assumes that the matter fields will not backreact on the wormhole spacetimes, i.e., we shall study the problem in the probe limit case. We point out the differences in the distribution of dark matter comparing to the location of it in the vicinity of rotating magnetized black holes.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
The application of semiconductor nanocrystals containing cadmium, lead, selenium and mercury as constituent elements is strictly limited by concerns about environmental pollution and health effects. Nanocrystals free of these toxic elements are being pushed to the forefront of nanocrystal research because of their environmentally friendly advantages and attractive photophysical properties on recent advances in colloidal synthesis, excellent optical properties, optoelectronic device applications, and biological applications of these environmentally friendly fluorescent nanocrystals. In this context, the first topic in this review paper introduces group IV semiconductors. In particular, the unique light emitting properties generated in silicon nanocrystals of diameters smaller than bulk exciton Bohr radius are highlighted. Next the topic turns to the nanocrystals of group III–V semiconductors. After that, attentions are paid to the lead-free perovskite nanocrystals such as tin-based halide perovskite and double perovskite structures. Recent efforts on how to control nanostructures to enhance photoluminescence quantum yields is highlighted for each semiconductor nanocrystal. Finally, the remaining challenges that must be overcome to realize nontoxic optoelectronic devices will be discussed.
Technology (General), Nuclear and particle physics. Atomic energy. Radioactivity
Marius Gaudesius, Yong-Chang Zhang, Thomas Pohl
et al.
Considering light-mediated long-range interactions between cold atoms in a magneto-optical trap (MOT), we present numerical evidence of a nonequilibrium steady state (NESS) for sufficiently large number of atoms (><inline-formula><math display="inline"><semantics><msup><mn>10</mn><mn>8</mn></msup></semantics></math></inline-formula>). This state manifests itself as the appearance of an anisotropic distribution of velocity when a MOT approaches the threshold beyond which self-oscillating instabilities occur. Our three-dimensional (3D) spatiotemporal model with nonlocal spatial dependencies stemming from the interatomic interactions has recently been compared successfully to predict different instability thresholds and regimes in experiments with rubidium atoms. The behavior of the NESS is studied as a function of the main MOT parameters, including its spatiotemporal characteristics.
Nuclear and particle physics. Atomic energy. Radioactivity
The variations of neutral temperature in the mesosphere and lower thermosphere (MLT) region, during the 7–8 September 2017 intense geomagnetic storm, are studied using observations by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. They are also studied using simulations by the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM). The neutral temperature data cover the altitudes from 80 km to 110 km between 83° N and 52° S latitude, obtained from both SABER observations and model simulations. The SABER observations reveal that temperature increases (the maximum increase is larger than 35 K at ~108 km) and decreases (the maximum decrease is larger than 20 K at ~105 km) during the geomagnetic storm. The storm effects penetrate down to ~80 km. In observations, temperature variations corresponding to the storm show hemispheric asymmetry. That is, the variations of temperature are more prominent in the northern hemisphere than in the southern hemisphere. Conversely, the TIMEGCM outputs agree with the observations in general but overestimate the temperature increases and underestimate the temperature decreases at high and middle latitudes. Meanwhile, the simulations show stronger temperature decreases and weaker temperature increases than observations at low latitudes. After analyzing the temperature variations, we suggest that vertical winds may play an important role in inducing these significant variations of temperature in the MLT region.
Abstract Recently, the LHCb Collaboration performed first search for the rare radiative $$\Xi _{b}^{-}\rightarrow \Xi ^{-}\gamma $$ Ξ b - → Ξ - γ decay and put an upper limit, $$\mathcal{B}(\Xi _{b}^{-}\rightarrow \Xi ^{-}\gamma ) < 1.3 \times 10^{-4}$$ B ( Ξ b - → Ξ - γ ) < 1.3 × 10 - 4 , on its branching ratio. The measurement agrees well with existing theory prediction using SU(3) flavor symmetry method, but shows a slight tension with the previous prediction from light-cone sum rules. Inspired by this, we investigate this decay as well as other radiative decays of $$\Xi _b^{0(-)}(\Xi ^{'-}_{b})$$ Ξ b 0 ( - ) ( Ξ b ′ - ) to $$\Xi ^{0(-)}$$ Ξ 0 ( - ) and $$\Sigma ^{0(-)}$$ Σ 0 ( - ) baryons using the form factors calculated from light-cone QCD sum rules in full theory. we obtain $$ \mathcal{B}(\Xi _{b}^{-}\rightarrow \Xi ^{-}\gamma )=1.08^{+0.63}_{-0.49} \times 10^{-5} $$ B ( Ξ b - → Ξ - γ ) = 1 . 08 - 0.49 + 0.63 × 10 - 5 , which lies below the upper limit set by LHCb and is consistent with flavor-symmetry driven prediction. Our predictions on other channels may be checked in experiment and by other phenomenological approaches.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Motivated by the first measured Δ+→pe+e− decay by the HADES Collaboration, electromagnetic Dalitz baryon decays from the spin 32 decuplet (T10) to the spin 12 octet (T8) baryons are investigated by using the SU(3) flavor symmetry/breaking in this paper. All decay amplitudes of T10→T8ℓ+ℓ−(ℓ=e,μ) electromagnetic Dalitz decays could be related by the SU(3) flavor symmetry/breaking, so the amplitudes can be obtained by the measured branching ratio of Δ+→pe+e− decay from the HADES Collaboration. The branching ratios, the lepton flavor universality, and the ratios B(T10→T8ℓ+ℓ−)B(T10→T8γ) are predicted by the relevant experimental data. T10→T8μ+μ− electromagnetic Dalitz decays are studied for the first time. All predicted B(T10→T8ℓ+ℓ−) except B(Ξ⁎0→Ξ0μ+μ−) and B(Ξ⁎−→Ξ−μ+μ−) are on the order of O(10−5−10−7), and these decays could be observed and could be used to test the SU(3) flavor symmetry/breaking approach in the electromagnetic Dalitz decays by HADES, PANDA, BESIII, and other experiments in the near future.
Nuclear and particle physics. Atomic energy. Radioactivity
Jonathan C. Wong, Andrei Shishlo, Alexander Aleksandrov
et al.
Utilizing noninvasive 2D scans with laser wires, we tomographically reconstructed the 4D transverse phase space distribution of a 1-GeV hydrogen ion (i.e., H^{-}) beam during operation. The 4D tomography is based on two new advances. First, we extended the formulation of maximum entropy phase space tomography to take 2D projections as input and derived theoretical results relevant to our application. Second, we introduced the method of “perpendicular scans” to obtain cross-plane information from a laser wire emittance scanner. Perpendicular scans are two unconventional 2D measurements performed with perpendicular front and back wires. In contrast, only parallel front and back wires (i.e., “parallel scans”) are utilized in ordinary measurements of the horizontal and vertical 2D phase space distributions. When we applied the technique to the laser emittance station in the high-energy beam transport of the Spallation Neutron Source, experimental results showed that perpendicular scans can provide significant new information to the reconstructed 4D phase space distribution.
Nuclear and particle physics. Atomic energy. Radioactivity
A. Hamaker1,2,3∗, E. Leistenschneider1,2,†, R. Jain, G. Bollen, S.A. Giuliani, K. Lund, W. Nazarewicz, L. Neufcourt, C. Nicoloff, D. Puentes, R. Ringle, C.S. Sumithrarachchi, I.T. Yandow Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA. National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA. Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA. European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT-FBK), Trento, Italy. Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom. ∗Corresponding author: hamaker@nscl.msu.edu †Current address: CERN, Geneva, Switzerland. Protons and neutrons in the atomic nucleus move in shells analogous to the electronic shell structures of atoms. Nuclear shell structure varies across the nuclear landscape due to changes of the nuclear mean field with the number of neutrons N and protons Z. These variations can be probed with mass differences. The N=Z=40 selfconjugate nucleus Zr is of particular interest as its proton and neutron shell structures are expected to be very similar, and its ground state is highly deformed. In this work, we provide evidence for the existence of a deformed double shell closure in Zr through high precision Penning trap mass measurements of Zr. Our new mass values show that Zr is significantly lighter, and thus more bound than previously determined. This can be attributed to the deformed shell closure at N=Z=40 and the large Wigner energy. Our statistical Bayesian model mixing analysis employing several global nuclear mass models demonstrates difficulties with reproducing the observed mass anomaly using current theory. Understanding the mechanisms of structural evolution, especially for exotic nuclei far from the beta stability line, is a major challenge in nuclear science. In this context, a rich territory for studies of basic nuclear concepts is the neutron-deficient region around mass number A = 80. The nuclei in this region rapidly change their properties with proton and neutron numbers. Indeed, some of these nuclei are among the most deformed in the nuclear chart and exhibit collective behaviour, while others show noncollective excitation patterns characteristic of spherical systems. The appearance of strongly deformed configurations around Zr has been attributed to the population of the intruder g9/2 orbitals separated by the spherical N = Z = 40 subshell closure from the upper-pf shell. This particular shell structure results in coexisting configurations of different shapes predicted by theory. In particular, for the nucleus Zr, spherical and deformed (prolate, oblate, and triaxial) structures are expected to coexist at low energies, and their competition strongly depends on the size of the calculated spherical N = Z = 40 gap. Experimentally, Zr has a very large prolate quadrupole deformation β2 ≈ 0.4. Within the mean-field theory, this has been attributed to the appearance of the large deformed gap at N = Z = 40 in the deformed single-particle spectrum. Consequently, the nucleus Zr can be viewed as a deformed doublymagic system. In addition to shape-coexistence effects, Zr is a great laboratory for isospin physics. Having equal number of protons and neutrons, this nucleus is self-conjugate; hence, it offers a unique venue to study proton-neutron pairing, isospin breaking effects, and the Wigner energy reflecting an additional binding in self-conjugate nuclei and their neighbours. The mass of an isotope is a sensitive indicator of the underlying shell structure as it reflects the net energy content of a nucleus, including the binding energy. Hence, doubly-magic nuclei are significantly lighter, or more bound, compared to their neighbours. Due to a lack of precision mass measurement data on Zr and its neighbours, it is difficult to characterize the size of the shell effect responsible for the large deformation of Zr. To this end, we performed high precision Penning trap mass spectrometry of four neutron-deficient zirconium isotopes – Zr – and analysed the local trends of the binding-energy surface by studying several bindingenergy indicators. To quantify our findings, experimental patterns have been interpreted using global nuclear mass models augmented by a Bayesian model averaging analysis.
To improve the ability of particle identification of the RIBLL2 separator at the HIRFL-CSR complex, a new high-performance detector for measuring fragment starting time and position at the F1 dispersive plane has been constructed and installed, and a method for achieving precise B\r{ho} determination has been developed using the experimentally derived ion-optical transfer matrix elements from the measured position and ToF information. Using the high-performance detectors and the precise B\r{ho} determination method, the fragments produced by the fragmentation of 78Kr at 300 MeV/nucleon were identified clearly at the RIBLL2-ETF under full momentum acceptance. The atomic number Z resolution of σZ~0.19 and the mass-to-charge ratio A/Q resolution of σA/Q~5.8e-3 were obtained for the 75As33+ fragment. This great improvement will increase the collection efficiency of exotic nuclei, extend the range of nuclei of interest from the A<40 mass region up to the A~80 mass region, and promote the development of radioactive nuclear beam experiments at the RIBLL2 separator.