Nuclear Theory·nucl-th

Monday·July 8, 2024

20 papers—7 primary·13 cross-listed

01
Quantum Monte Carlo calculations of magnetic form factors in light nuclei
G. Chambers-Wall🇺🇸 · A. Gnech🇺🇸 · G. B. King🇺🇸 · S. Pastore🇺🇸 · M. Piarulli🇺🇸 · R. Schiavilla🇺🇸 · R. B. Wiringa🇺🇸
We present Quantum Monte Carlo calculations of magnetic form factors in $A = 6 - 10$ nuclei, based on Norfolk two- and three-nucleon interactions, and associated one- and two-body electromagnetic currents. Agreement with the available experimental data for $^{6}$ Li, $^{7}$ Li, $^{9}$ Be and $^{10}$ B up to values of momentum transfer $q \sim 3$ fm $^{- 1}$ is achieved when two-nucleon currents are accounted for. We present a set of predictions for the magnetic form factors of $^{7}$ Be, $^{8}$ Li, $^{9}$ Li, and $^{9}$ C. In these systems, two-body currents account for $\sim 40 - 60%$ of the total magnetic strength. Measurements in any of these radioactive systems would provide valuable insights on the nuclear magnetic structure emerging from the underlying many-nucleon dynamics. A particularly interesting case is that of $^{7}$ Be, as it would enable investigations of the magnetic structure of mirror nuclei.
nucl-thPRL(2024)·19 citations
02
Examination of the evidence for a proton halo in $^{22}$ Al
K. Y. Zhang · C. Pan · Sibo Wang
More and more halo nuclei or candidates have been identified or suggested in experiments in recent years. It was declared that the halo structure of $^{22}$ Al is revealed by the large isospin asymmetry in $^{22}$ Si/ $^{22}$ O mirror Gamow-Teller transitions [Phys. Rev. Lett. 125, 192503 (2020)]. We highlight that a significant mirror asymmetry already exists between wave functions of the likely unbound nucleus $^{22}$ Si and the doubly-magic nucleus $^{22}$ O, which largely explains the observed asymmetry in the transitions. Furthermore, these transitions involve only the $1^{+}$ excited states of the daughter nuclei $^{22}$ Al and $^{22}$ F. The $1^{+}$ state of $^{22}$ Al cannot be considered a halo state due to its proton-unbound nature. An analysis of the spin-parity suggests that a weakly bound $2 s_{1/2}$ valence proton in the ground state of $^{22}$ Al is improbable. To investigate the shell structure for the ground state of $^{22}$ Al, we employ the state-of-the-art deformed and triaxial relativistic Hartree-Bogoliubov theories in continuum. We find that a small $s$ -wave component of $5%$ appears for the weakly bound valence proton in $^{22}$ Al only when triaxial deformation is considered. While the examination of densities and rms radii indicates that this small $s$ -wave component is insufficient to form a discernible proton halo in $^{22}$ Al, slightly larger $2 s_{1/2}$ occupations have been reported in other recent theoretical results. The question of how many low- $ℓ$ components are sufficient to form a proton halo in the presence of the Coulomb barrier remains open. Thus, future measurements of reaction or interaction cross sections and momentum distributions of breakup fragments are highly desirable to verify whether $^{22}$ Al is a halo nucleus.
nucl-thnucl-exPRC(2024)·25 citations
03
Interplay of single-particle and collective modes in the $^{12}$ C(p,2p) reaction near 100 MeV
A. Deltuva · E. Cravo · R. Crespo · D. Jurčiukonis
The $^{12}$ C(p,2p) $^{11}$ B reaction at $E_{p} = 98.7$ MeV proton beam energy is analyzed using a rigorous three-particle scattering formalism extended to include the internal excitation of the nuclear core or residual nucleus. The excitation proceeds via the core interaction with any of the external nucleons. We assume the $^{11}$ B ground and low-lying excited states [ $\frac{3}{2}^{-}$ (0.0 MeV), $\frac{5}{2}^{-}$ (4.45 MeV), $\frac{7}{2}^{-}$ (6.74 MeV)] and the excited states [ $\frac{1}{2}^{-}$ (2.12 MeV), $\frac{3}{2}^{-}$ (5.02 MeV)] to be members of $K = \frac{3}{2}^{-}$ and $K = \frac{1}{2}^{-}$ rotational bands, respectively. The dynamical core excitation results in a significant cross section for the reaction leading to the $\frac{5}{2}^{-}$ (4.45 MeV) excited state of $^{11}$ B that cannot be populated through the single-particle excitation mechanism. The detailed agreement between the theoretical calculations and data depends on the used optical model parametrizations and the kinematical configuration of the detected nucleons.
nucl-thPLB(2024)·2 citations
04
Role of clustered nuclear geometry in particle production through p-C and p-O collisions at the Large Hadron Collider
Aswathy Menon K R🇮🇳 · Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳
Long-range multi-particle correlations in heavy-ion collisions have shown conclusive evidence of the hydrodynamic behavior of strongly interacting matter and are associated with the final-state azimuthal momentum anisotropy. In small collision systems, azimuthal anisotropy can be influenced by the hadronization mechanism and residual jet-like correlations. Thus, one of the motives of the planned p--O and O--O collisions at the LHC and RHIC is to understand the origin of small system collectivity. As the anisotropic flow coefficients ( $v_{n}$ ) are sensitive to the initial-state effects including nuclear shape, deformation, and charge density profiles, studies involving $^{12}$ C and $^{16}$ O nuclei are transpiring due to the presence of exotic $α$ ( $^{4}$ He) clusters in such nuclei. In this study, for the first time, we investigate the effects of nuclear $α$ --clusters on the azimuthal anisotropy of the final-state hadrons in p--C and p--O collisions at $s_{NN} = 9.9$ ~TeV within a multi-phase transport model framework. We report the transverse momentum ( $p_{T}$ ) and pseudorapidity ( $η$ ) spectra, participant eccentricity ( $ϵ_{2}$ ) and triangularity ( $ϵ_{3}$ ), and estimate the elliptic flow ( $v_{2}$ ) and triangular flow ( $v_{3}$ ) of the final-state hadrons using the two-particle cumulant method. These results are compared with a model-independent Sum of Gaussians (SOG) type nuclear density profile for $^{12}$ C and $^{16}$ O nuclei.
nucl-thhep-exhep-phnucl-exEPJA(2025)·10 citations
05
Probing the equilibration of the QCD matter created in heavy-ion collisions with dileptons
Xiang-Yu Wu🇨🇦 · Lipei Du🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦
A systematic study of intermediate invariant mass dilepton production in Pb+Pb collisions at $s_{N N} = 5.02$ TeV is performed, using next-to-leading-order (NLO) thermal QCD dilepton emission rates with a multistage dynamical approach which includes event-by-event IP-Glasma initial conditions, relativistic viscous fluid dynamics, and a hadronic afterburner. Considering dilepton yield and anisotropic flow, special attention is paid to the out-of-equilibrium aspects, both thermal and chemical, and to the contribution of the Drell-Yan process. The relative contribution of each of those different channels to dilepton observables is calculated and discussed.
nucl-thhep-phnucl-exPRC(2024)·23 citations
06
Study of the neutrino-oxygen cross sections of the charged-current reaction 16O( $ν ˉ_{e}, e^{+}$ )16N(0 MeV, $2^{-}$ ) and the neutral-current reaction 16O( $ν, ν$ ')16O(12.97/12.53 MeV, $2^{-}$ ), producing high-energy gamma rays
Makoto Sakuda🇯🇵 · Toshio Suzuki🇯🇵 · Ken'ichiro Nakazato🇯🇵 · Hideyuki Suzuki🇯🇵
In the previous work, we discussed the cross section and the detection of 4.4-MeV $γ$ rays produced in the neutrino neutral-current (NC) reaction $^{16}$ O( $ν, ν^{'}$ ) $^{16}$ O(12.97 MeV and 12.53 MeV, $2^{-}$ ) in a water Cherenkov detector at the low energy below 100 MeV. In this report, we further investigated both the charged-current (CC) reaction $^{16}$ O( $ν ˉ_{e}, e^{+}$ ) $^{16}$ N(0 MeV, $2^{-}$ ) and the NC reaction $^{16}$ O( $ν, ν^{'}$ ) $^{16}$ O(12.97 MeV and 12.53 MeV, $2^{-}$ ), producing high-energy $γ$ rays, in which the more solid identification of the reactions can be applied via the coincidence method.
nucl-thhep-phnucl-exPTEP(2024)·0 citations
07
Constraining the high-density behavior of nuclear symmetry energy with direct Urca processes
Olfa Boukari · Tuhin Malik · Aziz Rabhi · Constança Providência
The density dependence of the symmetry energy in relativistic mean-field models with density dependent couplings is discussed in terms of the possible opening of nucleonic direct Urca processes inside neutron stars, which induce a very rapid cooling of the star. The modification of the parametrization of the isospin channel of two models, DD2 and DDMEX, keeping the same isoscalar properties is considered and the implications are discussed. Within the models discussed it is not possible the onset of nucleonic direct Urca processes in stars with a mass below $\sim 1.6 M_{⊙}$ if chiral effective field theory constraints for neutron matter are imposed. A Bayesian inference calculation confirms the low probability that nucleonic direct Urca processes occur inside stars with masses below 1.8 $M_{⊙}$ , considering the isoscalar channel of the equation of state described by DD2 or DDMEX and the same symmetry energy at saturation. The lowest masses allowing direct Urca processes are associated with a slope of the symmetry energy above $60$ MeV and most likely a positive symmetry energy incompressibility. It is shown that the parametrization of the isospin channel proposed destroys the correlation between symmetry energy slope and incompressibility previously identified in several works.
nucl-thastro-ph.HEPRC(2024)·5 citations
08
Backward DVCS on the pion in Sullivan processes
Abigail Rodrigues Castro🇫🇷 · Cedric Mezrag🇫🇷 · Jose M. Morgado Chávez🇫🇷 · Bernard Pire🇫🇷
The purpose of this work is to do a systematic feasibility study of measuring in backward region deeply virtual Compton scattering on the pion in Sullivan processes in the framework of collinear QCD factorization where pion to photon transition distribution amplitudes (TDAs) describe the photon content of the $π$ meson. Our approach employs TDAs based on the overlap of light front wave functions, using a previously developed pion light-front wave function and deriving a consistent model for the light front wave functions of the photon. This work is expected to lead us to an estimate of the cross-sections that could be measured in the future U.S. and China's electron-ion colliders. It will also provide a comparison with the forward Sullivan DVCS case, which gives access to pion GPDs and for which a strong signal is expected.
↳ hep-phhep-exhep-thnucl-ex+1PoS(2025)·0 citations
09
$B_{c}, B_{c}^{*}, B_{s}, B_{s}^{*}, D_{s}$ and $D_{s}^{*}$ mass shift in a nuclear medium
S. L. P. G. Beres🇧🇷
For the first time, we estimate the in-medium mass shift of the two-flavored heavy mesons $B_{c}, B_{c}^{*}, B_{s}, B_{s}^{*}, D_{s}$ and $D_{s}^{*}$ in symmetric nuclear matter. The estimates are made by evaluating the lowest order one-loop self-energies. The enhanced excitations of intermediate state heavy-light quark mesons in symmetric nuclear matter are the origin of their negative mass shift. Our results show that the magnitude of the mass shift for the $B_{c}$ meson ( $b ˉ c$ or $b c ˉ$ ) is larger than those of the $η_{c} (c ˉ c)$ and $η_{b} (b ˉ b)$ , different from a naive expectation that it would be in-between of them. While, that of the $B_{c}^{*}$ shows the in-between of the $J / ψ$ and $Υ$ . We observe that the lighter vector meson excitation in each meson self-energy gives a dominant contribution for the corresponding meson mass shift, $B_{c}, B_{s},$ and $D_{s}$ .
↳ hep-phnucl-thphysics.comp-ph0 citations
10
Suppressed Electric Quadrupole Collectivity in $^{49}$ Ti
T. J. Gray · J. M. Allmond · C. Benetti · C. Wibisono · L. Baby · A. Gargano · T. Miyagi · A. O. Macchiavelli · A. E. Stuchbery · J. L. Wood · S. Ajayi · J. Aragon and 25 other authors
Single-step Coulomb excitation of $^{46, 48, 49, 50}$ Ti is presented. A complete set of $E 2$ matrix elements for the quintuplet of states in $^{49}$ Ti, centered on the $2^{+}$ core excitation, was measured for the first time. A total of nine $E 2$ matrix elements are reported, four of which were previously unknown. $_{22}^{49}$ Ti $_{27}$ shows a $20%$ quenching in electric quadrupole transition strength as compared to its semi-magic $_{22}^{50}$ Ti $_{28}$ neighbour. This $20%$ quenching, while empirically unprecedented, can be explained with a remarkably simple two-state mixing model, which is also consistent with other ground-state properties such as the magnetic dipole moment and electric quadrupole moment. A connection to nucleon transfer data and the quenching of single-particle strength is also demonstrated. The simplicity of the $^{49}$ Ti- $^{50}$ Ti pair (i.e., approximate single- $j$ $0 f_{7/2}$ valence space and isolation of yrast states from non-yrast states) provides a unique opportunity to disentangle otherwise competing effects in the ground-state properties of atomic nuclei, the emergence of collectivity, and the role of proton-neutron interactions.
↳ nucl-exnucl-thPLB(2024)·5 citations
11
Three-dimensional Imaging of Pion using Lattice QCD: Generalized Parton Distributions
Heng-Tong Ding🇨🇳 · Xiang Gao🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Qi Shi🇨🇳 · Sergey Syritsyn🇺🇸 · Yong Zhao🇺🇸
In this work, we report a lattice calculation of $x$ -dependent valence pion generalized parton distributions (GPDs) at zero skewness with multiple values of the momentum transfer $- t$ . The calculations are based on an $N_{f} = 2 + 1$ gauge ensemble of highly improved staggered quarks with Wilson-Clover valence fermion. The lattice spacing is 0.04 fm, and the pion valence mass is tuned to be 300 MeV. We determine the Lorentz-invariant amplitudes of the quasi-GPD matrix elements for both symmetric and asymmetric momenta transfers with similar values and show the equivalence of both frames. Then, focusing on the asymmetric frame, we utilize a hybrid scheme to renormalize the quasi-GPD matrix elements obtained from the lattice calculations. After the Fourier transforms, the quasi-GPDs are then matched to the light-cone GPDs within the framework of large momentum effective theory with improved matching, including the next-to-next-to-leading order perturbative corrections, and leading renormalon and renormalization group resummations. We also present the 3-dimensional image of the pion in impact-parameter space through the Fourier transform of the momentum transfer $- t$ .
↳ hep-lathep-phnucl-exnucl-thJHEP(2025)·38 citations
12
Systematic uncertainty of offshell corrections and higher-twist contribution in DIS at large x
Matteo Cerutti🇺🇸 · Alberto Accardi🇺🇸 · Ishara P. Fernando🇺🇸 · Shujie Li🇺🇸
We study the systematic uncertainty and biases introduced by theoretical assumptions needed to include large- $x$ DIS data in a global QCD analysis. Working in the CTEQ-JLab framework, we focus on different implementations of higher-twist corrections to the nucleon structure functions and of offshell PDF deformations in deuteron targets and discuss how their interplay impacts the extraction of the $d$ -quark PDF and the calculation of the neutron structure function at large $x$ .
↳ hep-phhep-exnucl-thPoS(2025)·2 citations
13
Moment of inertia and compactness of quark stars within the context of $f (R, T, L_{m})$ gravity
Juan M. Z. Pretel🇧🇷
Within the metric formalism of $f (R, T, L_{m})$ gravity theories, we investigate the hydrostatic equilibrium structure of compact stars taking into account both isotropic and anisotropic pressure. For this purpose, we focus on the $f (R, T, L_{m}) = R + α T L_{m}$ model, where $α$ is a free parameter. We derive the modified TOV equations and the relativistic moment of inertia in the slowly rotating approximation. Using an equation of state (EoS) for color-superconducting quark stars, we examine the effects of the $α T L_{m}$ term on the different macroscopic properties of these stars. Our results reveal that the decrease of the parameter $α$ leads to a noticeable increase in the maximum-mass values. For negative $α$ with sufficiently small $∣ α ∣$ , we obtain a qualitative behavior similar to the general relativistic (GR) context, namely, it is possible to obtain a critical stellar configuration such that the mass reaches its maximum. However, for sufficiently large values of $∣ α ∣$ keeping negative $α$ , the critical point cannot be found on the mass-radius diagram. We also find that the inclusion of anisotropic pressure can provide masses and radii quite consistent with the current observational measurements, which opens an outstanding window onto the physics of anisotropic quark stars. By comparing the $I - C$ relations of isotropic quark stars in modified gravity, we show that such a correlation remains almost unchanged as the parameter $α$ varies from GR counterpart. On the other hand, given a fixed $α$ , the $I - C$ relation is insensitive to variations of the anisotropy parameter $β$ to $O (4%)$ .
↳ gr-qcastro-ph.HEnucl-thPhys.Scripta(2024)·16 citations
14
Revealing the nature of yrast states in neutron-rich polonium isotopes
R. Lică🇷🇴 · A. N. Andreyev🇬🇧 · H. Naïdja🇩🇿 · A. Blazhev🇩🇪 · P. Van Duppen🇧🇪 · B. Andel🇸🇰 · A. Algora🇪🇸 · S. Antalic🇸🇰 · J. Benito🇪🇸 · G. Benzoni🇮🇹 · T. Berry🇬🇧 · M. J. G. Borge🇪🇸 and 34 other authors
Polonium isotopes having two protons above the shell closure at $Z = 82$ show a wide variety of low-lying high-spin isomeric states across the whole chain. The structure of neutron-deficient isotopes up to $^{210}$ Po ( $N = 126$ ) is well established as they are easily produced through various methods. However, there is not much information available for the neutron-rich counterparts for which only selective techniques can be used for their production. We report on the first fast-timing measurements of yrast states up to the 8 $^{+}$ level in $^{214, 216, 218}$ Po isotopes produced in the $β^{-}$ decay of $^{214, 216, 218}$ Bi at ISOLDE, CERN. In particular, our new half-life value of 607(14) ps for the 8 $_{1}^{+}$ state in $^{214}$ Po is nearly 20 times shorter than the one available in literature and comparable with the newly measured half-lives of 409(16) and 628(25) ps for the corresponding 8 $_{1}^{+}$ states in $^{216, 218}$ Po, respectively. The measured $B (E 2; 8_{1}^{+} \to 6_{1}^{+})$ transition probability values follow an increasing trend relative to isotope mass, reaching a maximum for $^{216}$ Po. The increase contradicts the previous claims of isomerism for the $8^{+}$ yrast states in neutron-rich $^{214}$ Po and beyond. Together with the other measured yrast transitions, the $B (E 2)$ values provide a crucial test of the different theoretical approaches describing the underlying configurations of the yrast band. The new experimental results are compared to shell-model calculations using the KHPE and H208 effective interactions and their pairing modified versions, showing an increase in configuration mixing when moving towards the heavier isotopes.
↳ nucl-exnucl-thPRL(2025)·3 citations
15
Evaluation of phase shifts for non-relativistic elastic scattering using quantum computers
Francesco Turro🇺🇸 · Kyle A. Wendt🇺🇸 · Sofia Quaglioni🇺🇸 · Francesco Pederiva🇮🇹 · Alessandro Roggero🇮🇹
Simulations of scattering processes are essential in understanding the physics of our universe. Computing relevant scattering quantities from ab initio methods is extremely difficult on classical devices because of the substantial computational resources needed. This work reports the development of an algorithm that makes it possible to obtain phase shifts for generic non-relativistic elastic scattering processes on a quantum computer. This algorithm is based on extracting phase shifts from the direct implementation of the real-time evolution. The algorithm is improved by a variational procedure, making it more accurate and resistant to the quantum noise. The reliability of the algorithm is first demonstrated by means of classical numerical simulations for different potentials, and later tested on existing quantum hardware, specifically on IBM quantum processors.
↳ quant-phnucl-thPRC(2024)·19 citations
16
Nonlinear Schwinger mechanism in QCD, and Fredholm alternatives theorem
M. N. Ferreira🇨🇳 · J. Papavassiliou🇪🇸
We present a novel implementation of the Schwinger mechanism in QCD, which fixes uniquely the scale of the effective gluon mass and streamlines considerably the procedure of multiplicative renormalization. The key advantage of this method stems from the nonlinear nature of the dynamical equation that generates massless poles in the longitudinal sector of the three-gluon vertex. An exceptional feature of this approach is an extensive cancellation involving the components of the integral expression that determines the gluon mass; it is triggered once the Schwinger-Dyson equation of the pole-free part of the three-gluon vertex has been appropriately exploited. It turns out that this cancellation is driven by the so-called Fredholm alternatives theorem, which operates among the set of integral equations describing this system. Quite remarkably, in the linearized approximation this theorem enforces the exact masslessness of the gluon. Instead, the nonlinearity induced by the full treatment of the relevant kernel evades this theorem, allowing for the emergence of a nonvanishing mass. The numerical results obtained from the resulting equations are compatible with the lattice findings, and may be further refined through the inclusion of the remaining fundamental vertices of the theory.
↳ hep-phhep-lathep-thnucl-thEPJC(2024)·4 citations
17
Global analysis of fragmentation functions to charged hadrons with high-precision data from the LHC
Jun Gao🇨🇳 · ChongYang Liu🇨🇳 · XiaoMin Shen🇨🇳 · Hongxi Xing🇨🇳 · Yuxiang Zhao🇨🇳
Fragmentation functions (FFs) are essential non-perturbative QCD inputs for predicting hadron production cross sections in high energy scatterings. In this study, we present a joint determination of FFs for light charged hadrons through a global analysis at next-to-leading order (NLO) in QCD. Our analysis incorporates a wide range of precision measurements from the LHC, as well as data from electron-positron collisions and semi-inclusive deep inelastic scatterings. By including measurements of jet fragmentation at the LHC in our global analysis, we are able to impose strong constraints on the gluon FFs. A careful selection of hadron kinematics is applied to ensure the validity of factorization and perturbative calculations of QCD. In addition, we introduce several methodological advances in fitting, resulting in a flexible parametrization form and the inclusion of theoretical uncertainties from perturbative calculations. Our best-fit predictions show very good agreement with the global data, with $χ^{2} / N_{pt} \sim 0.90$ . We also generate a large number of Hessian error sets to estimate uncertainties and correlations of the extracted FFs. FFs to charged pions (kaons and protons) are well constrained for momentum fractions down to 0.01 (0.1). Total momentum of partons carried by light charged hadrons are determined precisely. Their values for $u$ , $d$ quarks and gluon saturate at about 50\% for a lower cut of the momentum fraction of 0.01. Pulls from individual datasets and impact of various choices of the analysis are also studied in details. Additionally, we present an update of the FMNLO program used for calculating hadron production cross sections. Our FFs, including the error sets (denoted as NPC23), are publicly available in the form of LHAPDF6 grids.
↳ hep-phhep-exnucl-exnucl-thPRD(2024)·49 citations
18
Observation of near-scission "polar" and "equatorial" proton emission in heavy-ion induced fission
Pawan Singh · Y. K. Gupta · G. K. Prajapati · B. N. Joshi · V. G. Prajapati · N. Sirswal · K. Ramachandran · A. S. Pradeep · V. S. Dagre · M. Kumar · A. Jhingan · N. Deshmukh and 4 other authors
Proton and $α$ -particle energy spectra were measured in coincidence with fission fragments at different relative angles in $^{16}$ O (96 MeV) + $^{232}$ Th reaction. The multiplicity spectra were analyzed within the framework of a Moving Source Disentangling Analysis (MSDA) to determine contributions from different emission stages. The MSDA conclusively shows ``Near Scission Emission (NSE)" as an essential component in the multiplicity spectra. In contrast to NSE $α$ particles which emit mainly perpendicular (``equatorial emission"), the NSE protons are observed to be emitted perpendicular as well as parallel (``polar emission") to the fission axis with similar intensities ( $\sim$ 20\% for each). Thus, around 40\% of total pre-scission protons are emitted near the scission stage, whereas the same fraction for $α$ particles is only around 10\%. The inevitable presence of ``polar" and ``equatorial" NSE protons in a heavy-ion induced fission has been observed for the first time. Present results open up a new avenue to study the heavy-ion induced fission dynamics.
↳ nucl-exnucl-thPLB(2024)·6 citations
19
Spectroscopy of deeply bound orbitals in neutron-rich Ca isotopes
P. J. Li🇨🇳 · J. Lee🇨🇳 · P. Doornenbal🇯🇵 · S. Chen🇨🇳 · S. Wang🇨🇳 · A. Obertelli🇩🇪 · Y. Chazono🇯🇵 · J. D. Holt🇨🇦 · B. S. Hu🇨🇦 · K. Ogata🇯🇵 · Y. Utsuno🇯🇵 · K. Yoshida🇯🇵 and 76 other authors
The calcium isotopes are an ideal system to investigate the evolution of shell structure and magic numbers. Although the properties of surface nucleons in calcium have been well studied, probing the structure of deeply bound nucleons remains a challenge. Here, we report on the first measurement of unbound states in $^{53}$ Ca and $^{55}$ Ca, populated from \ts{54,56}Ca( $p, p n$ ) reactions at a beam energy of around 216 MeV/nucleon at the RIKEN Radioactive Isotopes Beam Factory. The resonance properties, partial cross sections, and momentum distributions of these unbound states were analyzed. Orbital angular momentum $l$ assignments were extracted from momentum distributions based on calculations using the distorted wave impulse approximation (DWIA) reaction model. The resonances at excitation energies of 5516(41)\,keV in $^{53}$ Ca and 6000(250)\,keV in $^{55}$ Ca indicate a significant $l$ \, =\,3 component, providing the first experimental evidence for the $ν 0 f_{7/2}$ single-particle strength of unbound hole states in the neutron-rich Ca isotopes. The observed excitation energies and cross-sections point towards extremely localized and well separated strength distributions, with some fragmentation for the $ν 0 f_{7/2}$ orbital in $^{55}$ Ca. These results are in good agreement with predictions from shell-model calculations using the effective GXPF1Bs interaction and \textit{ab initio} calculations and diverge markedly from the experimental distributions in the nickel isotones at $Z = 28$ .
↳ nucl-exnucl-thPLB(2024)·6 citations
20
Internal structure of the $T_{cc} (3875)^{+}$ from its light-quark mass dependence
Michael Abolnikov🇩🇪 · Vadim Baru🇩🇪 · Evgeny Epelbaum🇩🇪 · Arseniy A. Filin🇩🇪 · Christoph Hanhart🇩🇪 · Lu Meng🇩🇪
We employ a chiral effective field theory-based approach to connect $D D^{*}$ scattering observables at the physical and variable pion masses accessible in lattice QCD simulations. We incorporate all relevant scales associated with three-body $D D π$ dynamics and the left-hand cut induced by the one-pion exchange for pion masses higher than the physical one, as required by analyticity and unitarity. By adjusting the contact interactions to match experimental data at the physical pion mass and lattice finite-volume energy levels at $m_{π} = 280$ MeV, we predict the trajectory of the $T_{cc}$ pole as a function of the pion mass, finding it consistent with the hadronic-molecule scenario. In particular, we find that the explicit treatment of the one-pion exchange has a pronounced effect on the pole trajectory for $m_{π} ≳ 230$ MeV by pushing it into the complex energy plane.
↳ hep-phhep-exhep-latnucl-thPLB(2025)·31 citations

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