Nuclear Theory
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Showing new listings for Friday, 22 November 2024
- [1] arXiv:2411.13622 [pdf, html, other]
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Title: Probing small neutron skin variations in isotope pairs by hyperon-antihyperon production in antiproton--nucleus interactionsFalk Schupp, Josef Pochodzalla, Michael Bölting, Martin Christiansen, Theodoros Gaitanos, Horst Lenske, Marcell SteinenComments: 9 figuresSubjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
We propose a new method to measure the evolution of the neutron skin thickness between different isotopes with small statistical and systematic uncertainties. We consider antiproton--nucleus interactions close to the production threshold of $\Lambda \overline{\Lambda }$ and $\Sigma^-\overline{\Lambda }$ pairs. At low energies, $\Lambda \overline{\Lambda }$ pairs are produced in $\overline{\text{p}} +\text{p}$ collisions, while $\Sigma^-\overline{\Lambda }$ pairs can only be produced in $\overline{\text{p}} +\text{n}$ interactions. Within a simple geometrical picture we show that the double ratio for the production of $\Sigma^-\overline{\Lambda }$ and $\Lambda \overline{\Lambda }$ pairs for two different isotopes are directly related to the variation of the neutron skin thickness between the two nuclei. Performing high statistics calculations with the Gießen Boltzmann--Uehling--Uhlenbeck (GiBUU) transport model for several isotope pairs covering a wide range of elements we verify a strong correlation between the double ratio from the full transport simulations and the schematic model. This correlation enables us to quantify the high potential of the proposed method for precise studies of neutron skin variations in isotope chains.
- [2] arXiv:2411.13963 [pdf, html, other]
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Title: Proton-neutron pair correlations in neutron-rich nucleiComments: 8 pages, 5 figuresSubjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
[Background] Nuclear pairing is a well-established many-body correlation, particularly among like particles in a spin-singlet state. However, the strength of spin-triplet proton-neutron (pn) pairing in nuclei has remained a long-standing and unresolved issue. [Purpose] The relative strength of spin-triplet pn pairing compared to spin-singlet one is investigated by introducing and analyzing the polarizability of the response to pn pair transfers. [Method] The nuclear energy-density functional method is employed. The ground state of the target nucleus is described using the Hartree-Fock-Bogoliubov approximation, which accounts for the conventional superfluidity of like-particle pairs. The response to pn pair transfers is then analyzed using the pn quasiparticle random-phase approximation. [Results] The spin-singlet pn-pair correlation is strongest at $N=Z$ and decreases monotonically with the increasing number of excess neutrons, whereas the spin-triplet pn-pair correlation is shown to depend non-monotonically on the neutron number and can be enhanced in cases where the pn-pair transfers involving the $\pi j_> \otimes \nu j_<$ configuration occur at low energy. [Conclusions] The shell effect, which uniquely appears in spin-triplet pn-pair correlation, serves as a key indicator of the strength of pn-pair correlations.
New submissions (showing 2 of 2 entries)
- [3] arXiv:2411.13845 (cross-list from hep-ph) [pdf, html, other]
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Title: Transverse spin effects and light-quark dipole moments at lepton collidersComments: 6 pages, 3 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
We propose to probe light-quark dipole interactions at lepton colliders using the azimuthal asymmetry of a collinear dihadron pair $(h_1h_2)$ produced in association with another hadron $h'$. This asymmetry, arising from quantum interference in the quark spin space, is exclusively sensitive to dipole interactions at the leading power of the new physics scale and simultaneously probes both the real and imaginary components of the dipole couplings. By combining all possible channels of $h'$, this method allows for disentangling the up and down quark dipole moments and has the potential to significantly strengthen current constraints by one to two orders of magnitude.
Cross submissions (showing 1 of 1 entries)
- [4] arXiv:2407.08342 (replaced) [pdf, html, other]
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Title: Contact operators in renormalization of attractive singular potentialsSubjects: Nuclear Theory (nucl-th)
We discuss renormalization of chiral nuclear forces in the 3P0 channel of N N scattering at next- to-next-to leading order (N2LO) if the one-pion exchange is treated nonperturbatively at leading order. The matrix elements of the subleading contact potentials become nearly dependent of each other for the so-called exceptional ultraviolet momentum cutoff, making it difficult to determine the strengths of those contact potentials from the empirical phase shifts, as reported in Ref. [1]. We argue that this issue can be resolved by adjusting the strategy by which the low-energy constants are deduced from the data, thus making those exceptional cutoffs amenable to chiral effective field theory.
- [5] arXiv:2408.13107 (replaced) [pdf, html, other]
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Title: Quarkyonic equation of state with a momentum dependent interaction and neutron star structureComments: 9 pages, 10 figures, 1 table. Comments are welcomeJournal-ref: Nuclear Physics A 1054 (2025) 122982Subjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
The structure and basic properties of dense nuclear matter still remain one of the open problems of Physics. In particular, the composition of the matter that composes neutron stars is under theoretical and experimental investigation. Among the theories that have been proposed, apart from the classical one where the composition is dominated by hadrons, the existence or coexistence of free quark matter is a dominant guess. An approach towards this solution is the phenomenological view according to which the existence of quarkyonic matter plays a dominant role in the construction of the equation of state (EOS). According to it the structure of the EOS is based on the existence of the quarkyonic particle which is a hybrid state of a particle that combines properties of hadronic and quark matter with a corresponding representation in momentum space. In this paper we propose a phenomenological model for quarkyonic matter, borrowed from corresponding applications in hadronic models, where the interaction in the quarkyonic matter depends not only on the position but also on the momentum of the quarkyonic particles. This consideration, as we demonstrate, can have a remarkable consequence on the shape of the EOS and thus on the properties of neutron stars, offering a sufficiently flexible model. Comparison with recent observational data can place constraints on the parameterization of the particular model and help improve its reliability.
- [6] arXiv:2409.11019 (replaced) [pdf, html, other]
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Title: Nuclear masses and fission barriers within the isospin-square liquid drop modelComments: 5 pages, 3 figuresSubjects: Nuclear Theory (nucl-th)
New liquid drop model with the isospin-square dependence of the volume and surface energy terms is applied to reproduce experimentally known masses of nuclei with number of protons and neutrons larger or equal to twenty. The ground-state microscopic energy corrections are taken into account. In spite of the fact that the model contains only six adjustable parameters, the quality of mass reproduction is good, and it is comparable with other contemporary mass models. Also, the fission barrier heights of actinide nuclei evaluated using the topographical theorem of Myers and Swiatecki are close to the data.
- [7] arXiv:2410.02473 (replaced) [pdf, html, other]
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Title: Simulating collectivity in dense baryon matter with multiple fluidsComments: Proceedings of SQM2024, Strasbourg (France), 3-7 June 2024. 4 pages, 3 figures. v2: version accepted for the publicationSubjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
We report on construction of a modern multi-fluid approach to heavy-ion collisions at FAIR/BES energies (MUFFIN) and show the reproduction of basic experimental observables in Au-Au collisions in the RHIC Beam Energy Scan program. We also show the $p_T$-differential and $p_T$-integrated polarization of (anti-)$\Lambda$ hyperons. In MUFFIN simulations, we observe a strong splitting between polarizations of $\Lambda$ and anti-$\Lambda$. The splitting is driven purely by a finite baryon chemical potential.
- [8] arXiv:2406.20009 (replaced) [pdf, html, other]
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Title: Lanczos, the transfer matrix, and the signal-to-noise problemComments: Improved spurious eigenvalue filtering, analysis of large-iteration behavior, presentation, and comparison with multi-state fitsSubjects: High Energy Physics - Lattice (hep-lat); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)
This work introduces a method for determining the energy spectrum of lattice quantum chromodynamics (LQCD) by applying the Lanczos algorithm to the transfer matrix and using a bootstrap generalization of the Cullum-Willoughby method to filter out spurious eigenvalues. Proof-of-principle analyses of the simple harmonic oscillator and the LQCD proton mass demonstrate that this method provides faster ground-state convergence than the "effective mass," which is related to the power-iteration algorithm. Lanczos provides more accurate energy estimates than multi-state fits to correlation functions with small imaginary times while achieving comparable statistical precision. Two-sided error bounds are computed for Lanczos results and guarantee that excited-state effects cannot shift Lanczos results far outside their statistical uncertainties. Further, Lanczos results avoid the exponential signal-to-noise degradation present in he power-iteration method / effective mass.
- [9] arXiv:2407.04155 (replaced) [pdf, html, other]
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Title: Evaluation of phase shifts for non-relativistic elastic scattering using quantum computersComments: 17 pages, 15 figures, 4 tablesSubjects: Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
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.
- [10] arXiv:2409.03373 (replaced) [pdf, html, other]
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Title: Doubly heavy tetraquark bound and resonant statesComments: 17 pages, 13 figures, version accepted by PRDJournal-ref: PhysRevD.110.094041 (2024)Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat); Nuclear Theory (nucl-th)
We calculate the energy spectrum of the S-wave doubly heavy tetraquark systems, including the $ QQ^{(\prime)}\bar q\bar q$, $QQ^{(\prime)}\bar s\bar q$, and $ QQ^{(\prime)}\bar s\bar s$ ($Q^{(\prime)}=b,c$ and $q=u,d$) systems within the constituent quark model. We use the complex scaling method to obtain bound states and resonant states simultaneously, and the Gaussian expansion method to solve the complex-scaled four-body Schrödinger equation. With a novel definition of the root-mean-square radii, we are able to distinguish between meson molecules and compact tetraquark states. The compact tetraquarks are further classified into three different types with distinct spatial configurations: compact even tetraquarks, compact diquark-antidiquark tetraquarks and compact diquark-centered tetraquarks. In the $ I(J^P)=0(1^+) $ $QQ\bar q\bar q$ system, there exists the $ D^*D $ molecular bound state with a binding energy of $ -14 $ MeV, which is the candidate for $ T_{cc}(3875)^+ $. The shallow $\bar B^*\bar B$ molecular bound state is the bottom analog of $T_{cc}(3875)^+$. Moreover, we identify two resonant states near the $D^*D^*$ and $\bar B^*\bar B^*$ thresholds. In the $ J^P=1^+ $ $bb\bar q\bar q\,(I=0)$ and $bb\bar s\bar q$ systems, we obtain deeply bound states with a compact diquark-centered tetraquark configuration and a dominant $\chi_{\bar 3_c\otimes 3_c}$ component, along with resonant states with similar configurations as their radial excitations. These states are the QCD analog of the helium atom. We also obtain some other bound states and resonant states with ``QCD hydrogen molecule" configurations. Moreover, we investigate the heavy quark mass dependence of the $ I(J^P)=0(1^+) $ $ QQ\bar q\bar q $ bound states. We strongly urge the experimental search for the predicted states.
- [11] arXiv:2409.07235 (replaced) [pdf, html, other]
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Title: Phenomenological model for the $\gamma^*\gamma \to \eta \pi^+ \pi^-$ reaction in the $f_1(1285)$ energy regionComments: 10 pages, 6 figures, 1 table, version to appear in Phys. Rev. DSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
Motivated by the ongoing analysis by the BESIII Collaboration on the single-tagged $e^+e^-\to e^+e^- \eta \pi^+\pi^-$ reaction, we present a phenomenological study of the diphoton fusion to $\eta \pi^+ \pi^-$, focusing on the production mechanism of the $f_1(1285)$ resonance. Contributions from the $f_1(1285)\to a_0(980)^\pm\, \pi^\mp$ and $f_1(1285)\to \sigma/f_0(500)\, \eta$ channels are included without introducing free parameters within an effective Lagrangian approach. Assuming the destructive interference between the amplitudes, we predict the invariant mass distributions, angular distributions, and total cross sections of the $\gamma^*\gamma \to \eta\pi^+\pi^-$ process, which will be tested by the forthcoming BESIII measurements.
- [12] arXiv:2410.00389 (replaced) [pdf, html, other]
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Title: Precise Mass Measurement of the Longest Odd-Odd Chain of \boldmath $1^+$ Ground StatesB. Liu, M. Brodeur, J.A. Clark, I. Dedes, J. Dudek, F. G. Kondev, D. Ray, G. Savard, A.A. Valverde, D.P. Burdette, A.M. Houff, R. Orford, W.S. Porter, F. Rivero, K.S. Sharma, L. VarrianoSubjects: Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
Precise mass measurements of the odd-odd $^{108, 110, 112, 114, 116}$Rh ground and isomeric states were performed using the Canadian Penning Trap at Argonne National Laboratory, showing a good agreement with recent JYFLTRAP measurements. A new possible isomeric state of $^{114}$Rh was also observed. These isotopes are part of the longest odd-odd chain of identical ground state spin-parity assignment, of 1$^+$, spanning $^{104-118}$Rh, despite being in a region of deformation. Realistic phenomenological mean-field calculations using ``universal'' Wood-Saxon Hamiltonian were performed, explaining this phenomenon for the first time. In addition, multi-quasiparticle blocking calculations were conducted to study the configuration of low-lying states in the odd-odd Rh nuclei and elucidate the observed anomalous isomeric yield ratio of $^{114}$Rh.