The European Physical Journal A最新文献

This work introduces a novel approach to the nuclear deformation factor (R_{text {AA}},) grounded in the dynamical effects of the Quark-Gluon Plasma on parton momentum. The approach uses the Blast-Wave method combined with Tsallis Statistics, within the Cooper–Frye freeze-out framework and, by profiting from appropriate simplifications, it gives analytical expressions that describe the observed (R_{AA}) for two sets of independent measurements at (sqrt{s}=2.76) TeV and (sqrt{s}=5.02) TeV. A nonlinear dynamical equation describes the dynamics and leads to log-periodic oscillations. With the analytical solutions for that equation, it is possible to link the dynamical approach with the complex-q formalism, which was proposed to describe the log-oscillations observed in experimental data.

With the advancement of first-principles calculations for baryon–baryon interactions, it becomes possible to obtain reliable hyperon–nucleon potentials by lattice QCD simulations with the HAL QCD method. High-precision few-body methods, such as the Gaussian Expansion Method (GEM), are applicable to solve quantum few-body systems up to four- and five-body systems. By combining the HAL QCD potentials with the GEM, one can predict the level structure of novel hypernuclei prior to experimental observation. In this review, we utilize the lattice QCD (NXi ) potential obtained by the HAL QCD method to investigate the few-body systems (NNXi ) and (NNNXi ). Our analysis indicates that the lightest bound (Xi ) hypernucleus is the (NNNXi ) system. To extract detailed information on the isospin and spin components of the (NXi ) interaction, we perform a four-body calculation for the (alpha alpha NXi ) system with the total isospin (T = 0) and (T = 1). We demonstrate that the level structure of this system is sensitive to the isospin and spin dependencies of the (NXi ) interaction. Furthermore, we propose experimental investigations to produce the (NNNXi ) and (alpha alpha NXi ) systems via the ((K^-, K^+)) and ((K^-, K^0)) reactions on ⁴He and ¹⁰B targets, respectively.

The energy distributions and the absolute yields of the long-range alpha particles and the tritons emitted in the thermal neutron induced ternary fission of ²³⁵U were measured using a twin-gridded ionization chamber and a highly pure thermal neutron beam of the Xi’an pulsed reactor. The mean energy and FWHM of the long-range alpha particles are (15.8 ± 0.3) MeV and (9.5 ± 0.3) MeV, respectively. The mean energy and FWHM of the tritons are (8.4 ± 0.3) MeV and (6.9 ± 0.4) MeV, respectively. The absolute yields of the long-range alpha particles and the tritons are (1.74 ± 0.05) × 10⁻³ and (1.21 ± 0.07) × 10⁻⁴, respectively. These results are discussed and compared with the data from previous measurements.

Nuclear physics experiments often involve complex geometrical configurations and intricate de-excitation schemes. Combined (gamma )-ray and conversion-electron spectroscopy experiments are prime examples. The design of the required instrumentation and the interpretation of the resulting data can greatly benefit from detailed simulations. Here, we report on extensions to the NPTool framework that enable an accurate representation of the experimental conditions associated with the sage and spede spectrometers. In addition, we introduce a program package for implementing complicated de-excitation patterns to complement the NPTool framework.

The transuranic-transfermium region ((Z ge 92)) hosts 221 known isomers across 160 isotopes. We examine their single-particle configurations and (alpha )-decay stability relative to ground states. Our analysis reveals that proton or neutron shell/subshell closures enhance isomer production and stabilize high-spin multi-quasiparticle configurations by strengthening couplings between complementary valence nucleons. Evidenced deformed sub-shell closure at (Z=96) [(Z=104)] boosts isomer yields attributed to occupations in (pi 5/2^+[642](1i_{13/2^+})), (pi 5/2^-[523](1h_{9/2^-})) and (pi 7/2^+[633](1i_{13/2^+})) [(pi 9/2^+[624](1i_{13/2^+})), (pi 1/2^-[521] (2f_{5/2^-})) and (pi 7/2^-[514](1h_{9/2^-}))] orbitals. A neutron deformed shell gap at (N=152) promotes isomerism in (N=151,153) isotones, primarily through (nu 5/2^+[622](1i_{11/2^+})), (nu 11/2^-[725](1j_{15/2^-})), and (nu 9/2^-[734](1j_{15/2^-})) excitations. The leading quasi-particle configurations in the isomers of (N=147)–149 isotones originate from neutrons/holes in the (nu 7/2^+[624](2g_{9/2^+})) and (nu 1/2^+[631] (3d_{5/2^+})) orbitals. The most stable isomers are predominantly driven by excitations in the (pi 1i_{13/2^+}) and (nu 1j_{15/2^-}) orbitals, under moderate prolate deformation, with key contributions from the (pi 11/2^+[615]), (pi 9/2^+[624]), (pi 7/2^+[633]), (pi 5/2^+[642]), (nu 11/2^-[725]), (nu 9/2^-[734]), and (nu 7/2^-[743]) states, then from deformed states of the (pi 2f_{7/2^-}) and (nu 1i_{11/2^+}) orbitals. Unlike heavier transfermiums, isomers (iso) of the Np–Es isotopes ((N=127)–144 isotones) exhibit no (alpha )-decays. The limited data constrain (log _{10} T_{alpha }^{text {(iso)}}) to a single linear trend versus (sqrt{Q_{alpha }^{-1}}) for favored and unfavored decays, unlike the ground-state decays where the trend’s slope correlates with the transferred angular momentum ((Delta l)), with stability enhanced against high-(Delta l) decays. The (alpha )-preformation factor in isomers (S_{alpha }^{text {(iso)}}) exceeds ground-state (gs) value only when (Q_{alpha }^{text {(iso)}} le Q_{alpha }^{text {(gs)}}) and (Delta l) is low; otherwise, (S_{alpha }^{text {(iso)}}) drops by 1–3 orders of magnitude, decreasing with both (Q_{alpha }^{text {(iso)}}) and (Delta l). This study reveals transactinide isomers as a promising research direction for finding stable configurations in undiscovered superheavy nuclei.

Investigating giant resonances is essential for deepening our understanding of nuclear structure and constraining the nuclear matter equation of state. In this work, we explore both giant dipole and quadrupole resonances in the superfluid nucleus (^{112})Sn based on a fully self-consistent quasiparticle-vibration coupling (QPVC) theory with the Skyrme interaction. Incorporating QPVC effects refines the description of the isoscalar and isovector modes by producing a downward energy shift and a broader width that are more consistent with experimental observations. Based on quasiparticle random phase approximation (QRPA) and QPVC model, the photoabsorption cross sections are further studied. It is shown that plane-wave (gamma )-photons predominantly excite the electric dipole (E1) mode. In contrast, when the nucleus aligns with the beam, vortex (gamma )-photons selectively excite the transition with a certain multipolarity through new selection rules given by angular momentum conservation. When the nucleus is offset from the beam axis, angular momentum selection rules relax, allowing the (E1) component to gradually recover and supplant the electric quadrupole or octupole transitions, while the oscillatory behavior of the Bessel functions governs fluctuations in the (E1) cross section. By comparing QRPA and QPVC results, QPVC shows its effect in the high energy range of vortex photon absorption cross sections at small impact parameters.

New experimental values for the (gamma )-ray emission intensities in the decay of (^text {235})U have been obtained by measurements of a 230-g certified triuranium octoxide sample enriched in (^text {235})U to 93.2% with a 70 cm(^{text {3}}) high-purity germanium detector over 1111 h. Calibration of energy scale and detection efficiency was performed by using peaks of (^text {235})U, (^text {234m})Pa, and U/Th series daughters. The revised intensities account for cascade summation, random coincidences, and interference from (gamma )-rays of other nuclides. Intensities of several (gamma ) transitions were found to have been significantly overestimated in earlier studies, by up to two orders of magnitude.

We introduce a new scheme for quantum circuit design called controlled gate networks. Rather than trying to reduce the complexity of individual unitary operations, the new strategy is to toggle between all of the unitary operations needed with the fewest number of gates. We present the general theory of controlled gate networks and show that, under quite general conditions, it can significantly reduce the number of two-qubit gates needed to produce linear combinations of unitary operators. The first example we consider is a variational subspace calculation for a two-qubit system. The second example is estimating the eigenvalues of a two-qubit Hamiltonian via the rodeo algorithm (Choi et al. in Phys Rev Lett 127(4):040505, 2021. https://doi.org/10.1103/PhysRevLett.127.040505) using operators that we call controlled reversal gates. We use the Quantinuum H1-2 and IBM Perth devices to realize the quantum circuits. The third example is the application of controlled gate networks to the controlled time evolution of a free nucleon on a three-dimensional lattice. For all of the examples, we show very substantial reductions in the number of two-qubit gates required. Our work demonstrates that controlled gate networks are a useful tool for reducing gate complexity in quantum algorithms for quantum many-body problems such as those relevant to nuclear physics.

In this study, we investigate the half-lives of the allowed combined (beta ^+) and electron-capture ((beta ^+)/EC) decays of nuclei with (Z = 31{-}40) and (A = 60{-}89) employing shell-model calculations within the (f_{5/2}pg_{9/2}) valence space using the JUN45 interaction. Using the quenching factor (q=0.71pm 0.01) for the weak axial coupling (g_A,) obtained from the analysis of pure Gamow–Teller (beta ^{-}) and (beta ^{+}) decay processes in nuclei with (Z = 31 {-} 40) and (A = 61{-}87,) the transition strengths and branching ratios for the (beta ^{+})/EC decays are evaluated. The experimental (beta )-decay half-lives are found to be rather well explained by the shell-model calculations. We investigate also the isospin mixing in the ground states of (^{64})Ge, (^{70})Se, and (^{78})Rb nuclei for non-analog (0^+ rightarrow 0^+) ((varDelta Tne 0)) (beta ) transitions from (^{64})Ge, (^{70})Se, and (^{78})Rb. A comprehensive study of the (beta ^{+})/EC-decay processes in nuclei in this region is done for the first time in the present work. Though the model space has a limitation due to the lack of its (f_{7/2}) and (g_{7/2}) spin-orbit partners, the results obtained can be considered reasonable.

Nuclear resonances provide a rich and versatile testbed for exploring fundamental aspects of physics, particularly within the domain of strongly correlated many-body systems. The overarching goal of the theory is to develop a consistent and predictive framework that is (i) capable of a spectroscopically accurate description and (ii) sufficiently general to be applied across different energy scales and transferable to a wide range of complex systems. Thoroughly capturing emergent collective phenomena that arise in nuclear media is the central challenge for the theory, which is discussed in this contribution. It concentrates on the themes inspired and influenced by Angela Bracco’s research, in particular, on the fragmentation patterns of the monopole and dipole responses of medium-heavy nuclei and associated open problems.