The European Physical Journal A最新文献

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Angular structure of many-body correlations in atomic nuclei 原子核中多体相关的角结构
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-29 DOI: 10.1140/epja/s10050-025-01679-2
Jean-Paul Blaizot, Giuliano Giacalone
{"title":"Angular structure of many-body correlations in atomic nuclei","authors":"Jean-Paul Blaizot,&nbsp;Giuliano Giacalone","doi":"10.1140/epja/s10050-025-01679-2","DOIUrl":"10.1140/epja/s10050-025-01679-2","url":null,"abstract":"<div><p>There is growing evidence that high-energy scattering processes involving nuclei can offer unique insights into the many-body correlations present in nuclear ground states, in particular those of <i>deformed</i> nuclei. These processes involve, for instance, the collective anisotropic flows in heavy-ion collisions, or the diffractive production of vector mesons in photo-nuclear (<span>(gamma A)</span>) interactions. In this paper, we use a classical approximation and simple analytical models in order to exhibit characteristic and universal features of ground-state correlation functions that result from the presence of a deformed intrinsic state. In the case of a small axial quadrupole deformation, we show that the random rotation of the intrinsic density of the nucleus leads to a specific quadrupole modulation of the lab-frame two-body density as a function of the relative azimuthal angle. As a phenomenological, albeit academic application, we analyze the diffractive production of vector mesons in high-energy <span>(gamma +^8)</span>Be collisions. This demonstrates with the simplest deformed nucleus how the two-body correlations impact the |<i>t</i>| dependence of the incoherent cross sections.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01679-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
((alpha , gamma )) cross section measurements in (^{102})Pd, (^{104})Pd and (^{106})Cd relevant to p process ((alpha , gamma ))在(^{102}) Pd、(^{104}) Pd和(^{106}) Cd中与p过程相关的截面测量
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-28 DOI: 10.1140/epja/s10050-025-01682-7
S. Harissopulos, V. Foteinou, G. Provatas, M. Axiotis, H.-W. Becker, A. Lagoyannis, P. Dimitriou
{"title":"((alpha , gamma )) cross section measurements in (^{102})Pd, (^{104})Pd and (^{106})Cd relevant to p process","authors":"S. Harissopulos,&nbsp;V. Foteinou,&nbsp;G. Provatas,&nbsp;M. Axiotis,&nbsp;H.-W. Becker,&nbsp;A. Lagoyannis,&nbsp;P. Dimitriou","doi":"10.1140/epja/s10050-025-01682-7","DOIUrl":"10.1140/epja/s10050-025-01682-7","url":null,"abstract":"<div><p>Cross-section measurements of (<span>(alpha ,gamma )</span>) reactions on <span>(^{106})</span>Cd, <span>(^{102})</span>Pd, and <span>(^{104})</span>Pd have been performed at center-of-mass energies between <span>(approx )</span> 7.9 and 11 MeV, which lie within the Gamow energy window relevant to the <i>p</i>-process. The determined total cross sections range between 1.4 and 257 <span>(mu )</span>b. Astrophysical <i>S</i> factors were also derived from the experimental cross sections. Statistical model calculations were performed using version 2.0 of the TALYS code and compared with the new data. An overall very good agreement between theory and experiment was found. In addition, the effect of different combinations of nuclear input parameters entering the stellar reaction-rate calculations was investigated.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Mass spectra of (qqbar{q}bar{q}), (ssbar{s}bar{s}) and (qqbar{s}bar{s}) tetraquarks using Regge phenomenology 利用Regge现象学研究(qqbar{q}bar{q}), (ssbar{s}bar{s})和(qqbar{s}bar{s})四夸克的质谱
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-26 DOI: 10.1140/epja/s10050-025-01701-7
Vandan Patel, Juhi Oudichhya, Ajay Kumar Rai
{"title":"Mass spectra of (qqbar{q}bar{q}), (ssbar{s}bar{s}) and (qqbar{s}bar{s}) tetraquarks using Regge phenomenology","authors":"Vandan Patel,&nbsp;Juhi Oudichhya,&nbsp;Ajay Kumar Rai","doi":"10.1140/epja/s10050-025-01701-7","DOIUrl":"10.1140/epja/s10050-025-01701-7","url":null,"abstract":"<div><p>In this paper, we explore the mass spectra of <span>(qqbar{q}bar{q})</span>, <span>(ssbar{s}bar{s})</span> and <span>(qqbar{s}bar{s})</span> tetraquarks by employing Regge phenomenology. We calculate the range for ground state masses of <span>(qqbar{s}bar{s})</span> tetraquarks, and estimate the Regge parameters for their trajectories in <span>((J,M^2))</span> plane. Using these Regge parameters we have calculated range for the excited state masses of <span>(qqbar{q}bar{q})</span>, <span>(ssbar{s}bar{s})</span> and <span>(qqbar{s}bar{s})</span> tetraquarks in <span>((J,M^2))</span> plane. Also, we have investigated the mass spectra of <span>(qqbar{q}bar{q})</span>, <span>(ssbar{s}bar{s})</span> and <span>(qqbar{s}bar{s})</span> tetraquarks for their excited radial states in <span>((n,M^2))</span> plane. We predict the potential quantum numbers of some newly observed experimental states, which necessitate additional validation, and assess the higher orbital and radial excited states that may be identified in the near future. The obtained mass relations and mass values of tetraquarks can be useful in future experimental searches and the spin-parity assignment of these states. Our findings provide valuable insights into the structure and properties of tetraquarks, contributing to the broader understanding of Quantum Chromodynamics (QCD).</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The theoretical study on multinucleon transfer reactions with a Pb target based on the HYBRID model 基于HYBRID模型的Pb靶多核子转移反应的理论研究
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-25 DOI: 10.1140/epja/s10050-025-01698-z
Xiao-Ye Zhang, Gen Zhang, Feng-Shou Zhang
{"title":"The theoretical study on multinucleon transfer reactions with a Pb target based on the HYBRID model","authors":"Xiao-Ye Zhang,&nbsp;Gen Zhang,&nbsp;Feng-Shou Zhang","doi":"10.1140/epja/s10050-025-01698-z","DOIUrl":"10.1140/epja/s10050-025-01698-z","url":null,"abstract":"<div><p>Based on the HYBRID model, the calculated production cross sections agree well with the experimental data in the reactions <span>(^{58})</span>Ni + <span>(^{208})</span>Pb and <span>(^{64})</span>Ni + <span>(^{130})</span>Te. In the <span>(^{124,130,136})</span>Te + <span>(^{208})</span>Pb reactions, it can be found that as the <i>N</i>/<i>Z</i> ratio of the projectile increases, the target is more likely to pick up neutrons, resulting in a shift of the cross sections of the target-like-fragment towards the neutron-rich side. The effect of the incident energy in <span>(^{136})</span>Te + <span>(^{208})</span>Pb reaction is studied, and it is found that the primary cross section of neutron-rich nuclei is sensitive to the incident energy, and the final cross section of neutron-deficient nuclei is sensitive to the incident energy.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Study of the (^{7})Li+(^{154})Sm inelastic reaction using particle-(gamma ) coincidences 利用粒子- (gamma )巧合研究(^{7}) Li+ (^{154}) Sm非弹性反应
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-24 DOI: 10.1140/epja/s10050-025-01677-4
F. Ramírez, D. A. Torres, J. R. B. Oliveira, N. H. Medina, A. S. Serra, V. A. B. Zagatto
{"title":"Study of the (^{7})Li+(^{154})Sm inelastic reaction using particle-(gamma ) coincidences","authors":"F. Ramírez,&nbsp;D. A. Torres,&nbsp;J. R. B. Oliveira,&nbsp;N. H. Medina,&nbsp;A. S. Serra,&nbsp;V. A. B. Zagatto","doi":"10.1140/epja/s10050-025-01677-4","DOIUrl":"10.1140/epja/s10050-025-01677-4","url":null,"abstract":"<div><p>The study of collectivity phenomena in atomic nuclei, such as nuclear deformation, provides essential information to characterize the nuclear potential in the different mass regions of the nuclear chart. The use of inelastic reactions in combination with particle-<span>(gamma )</span> coincidences is a powerful experimental tool utilized to characterize near-ground excited states in reactions using deformed nuclei as targets and light-beam isotopes. This allows for the simultaneous study of both the states of nuclei in the beam and the target. The present work reports the first attempt to study the first excited states of the deformed <span>(^{154})</span>Sm isotope by measuring the <b>Differential Cross-Section</b> of the inelastic excitation of the target system <span>(^{7})</span> Li beam <span>(+)</span> <span>(^{154})</span> Sm. The particle <span>(gamma )</span>-ray coincidence technique has been used to study the <span>(^7)</span>Li + <span>(^{154})</span>Sm inelastic reactions at 26 MeV beam energy. Charged particles were detected using an array of <span>(Delta E-E)</span> phoswich detectors, while <span>(gamma )</span>-ray radiation was registered using two arrays of LYSO(Ce) detectors. The results were analyzed using coupled-channel calculations with the FRESCO code of the inelastic cross-section for different nuclear potentials. The Differential Cross-Section for inelastic excitations of <span>(^{154})</span>Sm of <span>(2^+)</span> (<span>(E^{star }=0.082)</span> MeV), <span>(4^+)</span> (<span>(E^{star }=0.267)</span> MeV), and <span>(6^+)</span> (<span>(E^{star }=0.544)</span> MeV), as well as the <span>(1/2^-)</span> (<span>(E^{star }=0.478)</span> MeV) state of the <span>(^7)</span>Li projectile is reported for the first time. Theoretical comparisons suggest that the <span>(0^+rightarrow 4^+)</span> and <span>(0^+rightarrow 6^+)</span> transitions of <span>(^{154})</span> Sm are crucial to describe how these states are populated. In this work, the cross section of the inelastic scattering reaction <span>(^7)</span>Li<span>(+^{154})</span>Sm at 26 MeV beam energy was studied and compared with coupled channel calculations using modified potentials to understand the influence of different coupling mechanisms. The analysis of <span>(^{154})</span>Sm suggests that it should be considered a quantum rotor in which each excited state represents an addition of the angular momentum of <span>(l=2hbar )</span>. The experimental data also indicate that in addition to the ground state <span>(0^+)</span>, the <span>(2^+)</span> (<span>(E^{star }=0.082)</span> MeV), <span>(4^+)</span> (<span>(E^{star }=0.267)</span> MeV), and <span>(6^+)</span> (<span>(E^{star }=0.544)</span> MeV) states of the target nucleus should be added to the coupling scheme, as well as the ground state <span>(3/2^-)</span> and the <span>(1/2^-)</span> (<span>(E^{star }=0.478)</span> MeV) of the projectile nucleus.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The CERN n_TOF NEAR station for astrophysics- and application-related neutron activation measurements CERN n_TOF近站,用于天体物理和应用相关的中子活化测量
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-23 DOI: 10.1140/epja/s10050-025-01674-7
The n_TOF Collaboration
{"title":"The CERN n_TOF NEAR station for astrophysics- and application-related neutron activation measurements","authors":"The n_TOF Collaboration","doi":"10.1140/epja/s10050-025-01674-7","DOIUrl":"10.1140/epja/s10050-025-01674-7","url":null,"abstract":"<div><p>A new experimental area, the NEAR station, has recently been built at the CERN n_TOF facility, at a short distance from the spallation target (3 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a <span>(gamma )</span>-ray spectroscopy laboratory, the GEAR station, equipped with a high-efficiency HPGe detector, for the measurement of the activity resulting from irradiation of a sample in the NEAR station. The use of a moderator/filter assembly is envisaged, in order to produce a neutron beam with quasi-Maxwellian energy distribution, of different thermal energies, necessary for the determination of Maxwellian Averaged Cross Sections of astrophysical interest. A new fast-cycling activation technique is also being investigated for measurements of reactions leading to isotopes of very short half life.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01674-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145110453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Nonlocal (N-alpha ) potential 非局部(N-alpha )势
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-23 DOI: 10.1140/epja/s10050-025-01695-2
M. I. Jaghoub, T. Aqel
{"title":"Nonlocal (N-alpha ) potential","authors":"M. I. Jaghoub,&nbsp;T. Aqel","doi":"10.1140/epja/s10050-025-01695-2","DOIUrl":"10.1140/epja/s10050-025-01695-2","url":null,"abstract":"<div><p>We used a nonlocal potential to account explicitly for nonlocalities in the <span>(N-alpha )</span> scattering process. By fitting elastic <span>(N-alpha )</span> angular distributions, over the energy range <span>(0.84 - 20.97)</span> MeV, we determined individual sets of nonlocal potential parameters and two global sets of fixed parameters one for <span>(n-alpha )</span> and the other for <span>(p-alpha )</span> elastic scattering. Our nonlocal potential model reproduced the elastic angular distributions for <span>(N-alpha )</span> and the total elastic cross section for <span>(n-alpha )</span> well. In addition, we calculated the nonlocal potential phase shifts corresponding to neutron and proton scattering off alpha particles. Our determined phase shifts are in good agreement with the experimental values. In addition, our nonlocal parameters reproduced the position of the <span>(P3/2^-)</span> resonance for the <span>(n-alpha )</span> and <span>(p-alpha )</span> scattering processes well. Accounting explicitly for nonlocalities in the <span>(N-alpha )</span> interactions can benefit studies that consider the <span>(t(d,N)alpha )</span> fusion reactions. The <span>(t(d,n)alpha )</span> reaction is important for its 17.6 MeV energy yield per fusion reaction, for its carbon-free energy production. The less prominent reaction that leads to bremsstrahlung <span>(gamma )</span> radiation is important as it provides real-time diagnostics regarding the fusion reaction rate.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145110452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Hydrodynamic study on the evolution of magnetized viscous QGP in the transverse plane 磁化粘性QGP在横向面上演化的流体力学研究
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-21 DOI: 10.1140/epja/s10050-025-01676-5
M. Karimabadi, A. F. Kord, B. Azadegan
{"title":"Hydrodynamic study on the evolution of magnetized viscous QGP in the transverse plane","authors":"M. Karimabadi,&nbsp;A. F. Kord,&nbsp;B. Azadegan","doi":"10.1140/epja/s10050-025-01676-5","DOIUrl":"10.1140/epja/s10050-025-01676-5","url":null,"abstract":"<div><p>This study explores the evolution of magnetized quark-gluon plasma (QGP) within the framework of relativistic magnetohydrodynamics (MHD), with a focus on understanding its temporal and spatial dynamics under the influence of intense magnetic fields. We employ a second-order viscous corrections to investigate the QGP’s evolution, where the plasma is subjected to a magnetic field generated in the early stages of relativistic heavy-ion collisions. The system is assumed to exhibit boost invariance along the longitudinal beam axis (z-coordinate) while undergoing transverse expansion. The magnetic field is modeled as a function of the proper time <span>(tau )</span> and spatial coordinates (x, y), oriented perpendicular to the direction of fluid expansion. The QGP is assumed to possess infinite electrical conductivity. We solve the coupled Maxwell and conservation equations to obtain a detailed description of the energy density, flow velocity, and magnetic field evolution in the transverse plane of the viscous magnetized plasma. Additionally, we compute the hadron spectrum emerging from the freeze-out surface and compare our results with experimental observations, providing insights into the interplay between magnetization and the hydrodynamic evolution of QGP.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145090511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Beam position monitoring system based on SiC detectors 基于SiC探测器的波束位置监测系统
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-18 DOI: 10.1140/epja/s10050-025-01681-8
K. Piasecki, E. Piasecki, G. Colucci, J. Choiński, H. M. Jia, M. Kisieliński, M. Kowalczyk, C. J. Lin, M. Matuszewski, N. R. Ma, A. Trzcińska, M. Wolińska-Cichocka, B. Zalewski, L. Yang, H. Q. Zhang
{"title":"Beam position monitoring system based on SiC detectors","authors":"K. Piasecki,&nbsp;E. Piasecki,&nbsp;G. Colucci,&nbsp;J. Choiński,&nbsp;H. M. Jia,&nbsp;M. Kisieliński,&nbsp;M. Kowalczyk,&nbsp;C. J. Lin,&nbsp;M. Matuszewski,&nbsp;N. R. Ma,&nbsp;A. Trzcińska,&nbsp;M. Wolińska-Cichocka,&nbsp;B. Zalewski,&nbsp;L. Yang,&nbsp;H. Q. Zhang","doi":"10.1140/epja/s10050-025-01681-8","DOIUrl":"10.1140/epja/s10050-025-01681-8","url":null,"abstract":"<div><p>The simple system for beam spot position monitoring is described. It is based on the radiation-resistive SiC detectors. The visualization of the beam spot on the target is done with a dedicated BeamMon application using the ROOT environment.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01681-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On two nucleons near unitarity with perturbative pions 关于两个具有微扰介子的接近统一的核子
IF 2.8 3区 物理与天体物理
The European Physical Journal A Pub Date : 2025-09-17 DOI: 10.1140/epja/s10050-025-01675-6
Yu-Ping Teng, Harald W. Grießhammer
{"title":"On two nucleons near unitarity with perturbative pions","authors":"Yu-Ping Teng,&nbsp;Harald W. Grießhammer","doi":"10.1140/epja/s10050-025-01675-6","DOIUrl":"10.1140/epja/s10050-025-01675-6","url":null,"abstract":"<div><p>We explore the impact of perturbative pions on the Unitarity Expansion in the two-nucleon S-waves of Chiral Effective Field Theory at next-to-next-to leading order (<span>(textrm{N}^{2})</span>LO). Pion exchange explicitly breaks the nontrivial fixed point’s universality, i.e.  invariance of S waves under both conformal and Wigner’s combined <span>(textrm{SU}(4))</span> spin–isospin transformations. On the other hand, Unitarity explicitly breaks chiral symmetry. The two seem incompatible in their respective exact-symmetry limits. <span>({upchi }textrm{EFT})</span> with Perturbative Pions in the Unitarity Expansion resolves the apparent conflict in the Unitarity Window (phase shifts <span>(45^circ lesssim delta (k)lesssim 135^circ )</span>), i.e.  around momenta <span>(kapprox m_pi )</span> most relevant for low-energy nuclear systems. Its only LO scale is the scattering momentum; NLO adds only scattering length, effective range and non-iterated one-pion exchange (OPE); and <span>(textrm{N}^{2})</span>LO only once-iterated OPE. Agreement in the <span>({phantom {0}}^{1}textrm{S}_{0})</span> channel is very good. Apparently large discrepancies in the <span>({phantom {0}}^{3}textrm{S}_{1})</span> channel even at <span>(kapprox 100;textrm{MeV})</span> are remedied by taking at <span>(textrm{N}^{2})</span>LO only the central part of OPE. In contradistinction to the tensor part, it is identical in the <span>({phantom {0}}^{1}textrm{S}_{0})</span> and <span>({phantom {0}}^{3}textrm{S}_{1})</span> channels. Both channels then match empirical phase shifts and pole parameters well within mutually consistent quantitative theory uncertainty estimates. Pionic effects are small, even for <span>(kgtrsim m_pi )</span>. Empirical breakdown scales are consistent with <span>(overline{Lambda }_{textrm{NN}}=frac{16pi f_pi ^2}{g_A^2M}approx 300;textrm{MeV})</span>, where iterated OPE is not suppressed. We therefore conjecture: Both conformal and Wigner symmetry in the Unitarity Expansion show <i>persistence</i>, i.e.  the footprint of both combined dominates even for <span>(kgtrsim m_pi )</span> and is more relevant than chiral symmetry, so that the tensor/Wigner-<span>(textrm{SU}(4))</span> symmetry-breaking part of OPE does not enter before <span>(textrm{N}^{3})</span>LO. We also discuss the potential relevance of entanglement and possible resolution of a conflict with the strength of the tensor interaction in the large-<span>(N_C)</span> expansion.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 9","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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