The European Physical Journal A最新文献

{"title":"Existence of a fourth Airy elephant in the nuclear rainbows for (^{12})C+(^{12})C scattering","authors":"S. Ohkubo,&nbsp;Y. Hirabayashi","doi":"10.1140/epja/s10050-025-01649-8","DOIUrl":"10.1140/epja/s10050-025-01649-8","url":null,"abstract":"<div><p>The number of gross structures in the 90<span>(^circ )</span> excitation function for <span>(^{12})</span>C+<span>(^{12})</span>C elastic scattering-often called “Airy elephants”-has been of great interest. These structures are caused by refractive scattering and are separated by Airy minima. Their importance stems from their close relationship to the interaction potential between two <span>(^{12})</span>C nuclei, which also describes the molecular resonances of the compound system at lower energies. Although a unique deep potential was usually determined from rainbow scattering at higher energies, a puzzling discrepancy persisted: the energy at which the Airy minimum <i>A</i>1 crosses 90<span>(^circ )</span> was <span>(E_{c.m.}approx )</span> 67 MeV for <span>(^{12})</span>C+<span>(^{12})</span>C. This is remarkably low compared to approximately 100 MeV for both the <span>(^{16})</span>O+<span>(^{12})</span>C and <span>(^{16})</span>O+<span>(^{16})</span>O systems. This question remained unanswered until the discovery of the secondary rainbow in the <span>(^{12})</span>C+<span>(^{12})</span>C system. We report for the first time that the highest energy at which the dynamically generated Airy minimum of the secondary rainbow crosses 90<span>(^circ )</span> is about 100 MeV. This demonstrates that the fourth Airy elephant exists between the Airy minimum <i>A</i>1 of the primary nuclear rainbow and that, <span>(A1^{(S)})</span>, of the secondary rainbow. The long-standing problem concerning the Airy minima and Airy elephants has finally been resolved after decades of concern by recognizing the existence of a dynamically generated secondary rainbow in <span>(^{12})</span>C+<span>(^{12})</span>C scattering.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169391","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}

{"title":"Collective phenomena in chirally imbalanced medium","authors":"Sourav Duari,&nbsp;Nilanjan Chaudhuri,&nbsp;Sourav Sarkar,&nbsp;Pradip Roy","doi":"10.1140/epja/s10050-025-01628-z","DOIUrl":"10.1140/epja/s10050-025-01628-z","url":null,"abstract":"<div><p>We calculate the gluon polarization tensor for a chirally imbalanced plasma using hard thermal loop approximation in the real time formulation of thermal field theory. The dispersion relations obtained from the poles of the effective gluon propagator are solved numerically as well as analytically in appropriate limiting cases. It is seen that the degenerate transverse modes split into left and right handed circularly polarized modes. We also compute imaginary poles of the propagator which signal the presence of instability in the plasma. Relevant time scales for development of such instabilities are discussed in detail. Furthermore, we compute both the real and imaginary parts of the static heavy-quark potential in the chirally imbalanced plasma and argue that quarkonium suppression is enhanced due to the combined effects of a reduced debye screening length and an increased decay width. In addition, we calculate the gluon spectral density, sum rules and residues for various cases, providing a comprehensive understanding of the collective behaviour of the medium.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01628-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168411","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}

{"title":"Microscopic analysis of 18O + 76Se elastic and inelastic scattering at 275 MeV","authors":"A. Hemmdan,&nbsp;Ola Ramadan,&nbsp;M. A. Hassanain,&nbsp;Kassem O. Behairy,&nbsp;M. Anwar","doi":"10.1140/epja/s10050-025-01632-3","DOIUrl":"10.1140/epja/s10050-025-01632-3","url":null,"abstract":"<div><p>Microscopic analysis of the differential cross section for ¹⁸O + ⁷⁶Se elastic and inelastic scattering at energy 275 MeV in the framework of the optical model is presented. For the inelastic scattering, the distorted wave Born approximation (DWBA) and coupled channel (CC) approaches are taking into account to calculate the effect of the low-lying states, 0⁺ and 2⁺ for the two interacting nuclei, and their mutual excitation (2⁺, 2⁺). Two microscopic potentials are constructed based upon the single Yukawa S1Y and the density independent M3Y nucleon-nucleon interactions using double folding model, in addition to the complex phenomenological Woods-Saxon potential. Although the two microscopic potentials are used without any reduction factors, the S1Y potential described the data over all the angular range better compared to M3Ypotential. A small effect of the single excited channel of target and a relevant effect for mutual excitation on the elastic cross section are found. The success of S1Y potential in describing the data makes it promising in explaining the double charge exchange reactions.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01632-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168344","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}

{"title":"Possible explanation of the irregular energy dependence of the rapidity width of (phi ) mesons observed in Pb+Pb collisions","authors":"Tom Reichert,&nbsp;Jan Steinheimer,&nbsp;Marcus Bleicher","doi":"10.1140/epja/s10050-025-01645-y","DOIUrl":"10.1140/epja/s10050-025-01645-y","url":null,"abstract":"<div><p>Experimental data from the NA49 collaboration show an unexpectedly steep rise of the rapidity width of the <span>(phi )</span> meson as function of beam energy, which was suggested as possible interesting signal for novel physics. In this work we show that the Ultra-relativistic Quantum-Molecular-Dynamics (UrQMD) model is able to reproduce the shapes of the rapidity distributions of most measured hadrons and predicts a common linear increase of the width for all hadrons. Only when following the exact same analysis technique and experimental acceptance of the NA49 and NA61/SHINE collaborations, we find that the extracted value of the rapidity width of the <span>(phi )</span> increases drastically for the highest beam energy. We conclude that the observed steep increase of the <span>(phi )</span> rapidity width may be a problem of limited detector acceptance and the simplified Gaussian fit approximation.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01645-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168343","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}

{"title":"Polarization observables in double neutral pion photoproduction","authors":"The CBELSA/TAPS Collaboration","doi":"10.1140/epja/s10050-025-01612-7","DOIUrl":"10.1140/epja/s10050-025-01612-7","url":null,"abstract":"<div><p>Measurements of target asymmetries and double-polarization observables for the reaction <img> are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (<span>(hbox {C}_4hbox {H}_9)</span>OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from <img> to <img> and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of <img> and <span>({varDelta ^*})</span> resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6)<span>(times )</span>O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12287178/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144735987","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}

{"title":"Primordial black-hole formation and heavy r-process element synthesis from the cosmological QCD transition","authors":"Maël Gonin,&nbsp;Günther Hasinger,&nbsp;David Blaschke,&nbsp;Oleksii Ivanytskyi,&nbsp;Gerd Röpke","doi":"10.1140/epja/s10050-025-01639-w","DOIUrl":"10.1140/epja/s10050-025-01639-w","url":null,"abstract":"<div><p>We review the role of primordial black holes for illuminating the dark ages of the cosmological evolution and as dark matter candidates. We elucidate the role of phase transitions for primordial black hole formation in the early Universe and focus our attention to the cosmological QCD phase transition within a recent microscopical model. We explore the impact of physics beyond the Standard Model on the cosmic equation of state and the probability distribution for the formation of primordial black holes which serve as dark-matter candidates. We argue that besides primordial black holes also droplet-like quark-gluon plasma inhomogeneities may become gravitationally stabilized for a sufficiently long epoch to distill baryon number and form nuclear matter droplets which upon their evaporation may enrich the cosmos locally with heavy <i>r</i>-process elements already in the early Universe.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01639-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168342","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}

{"title":"(eta ), (eta ^prime ) mesons from lattice QCD in fully physical conditions","authors":"Konstantin Ottnad,&nbsp;Simone Bacchio,&nbsp;Jacob Finkenrath,&nbsp;Bartosz Kostrzewa,&nbsp;Marcus Petschlies,&nbsp;Ferenc Pittler,&nbsp;Carsten Urbach,&nbsp;Urs Wenger","doi":"10.1140/epja/s10050-025-01635-0","DOIUrl":"10.1140/epja/s10050-025-01635-0","url":null,"abstract":"<div><p>We determine masses and mixing parameters of the <span>(eta )</span> and <span>(eta ^prime )</span> meson in lattice QCD. The calculations are carried out on a set of 13 ETMC gauge ensembles with <span>(N_f=2+1+1)</span> (maximally) twisted-mass Clover-improved quarks. These ensemble cover four values of the lattice spacing <span>(a=0.057,textrm{fm},ldots ,0.092,textrm{fm})</span> and pion masses from 140 to <span>(360,textrm{MeV})</span>, including three ensembles at physical quark masses and six ensembles with <span>(M_pi &lt;200,textrm{MeV})</span>. The strange-quark contribution is treated in a mixed-action approach using Osterwalder–Seiler fermions to avoid complications due to flavor mixing in the heavy quark sector and to enable the use of the one-end trick in the computation of strange quark-disconnected diagrams. With the strange-quark mass tuned to its physical value and several ensembles having close-to-physical light-quark mass, uncertainties related to the chiral extrapolations are reduced significantly compared to earlier studies. Physical results are computed with fully controlled systematics from a combined chiral, continuum and infinite-volume extrapolation, and a full error budget is obtained from model averages over of various fit ansätze and data cuts. Our results for the masses are given by <span>(M_eta =551(16),textrm{MeV})</span> and <span>(M_{eta ^prime }=972(20),textrm{MeV})</span>, respectively, where statistical and systematic errors have been added in quadrature. For the mixing angle and decay-constant parameters the Feldmann–Kroll–Stech scheme is employed to compute them from pseudoscalar matrix elements in the quark-flavor basis. For the mixing angle we obtain <span>(phi ^textrm{phys}=39.3(2.0)^circ )</span> and our results for the decay-constant parameters are given by <span>(f_l^textrm{phys}=138.6(4.4),textrm{MeV})</span> and <span>(f_s^textrm{phys}=170.7(3.3),textrm{MeV})</span>.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12283833/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144710145","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}

{"title":"Why does transverse wobbling occur in Lutetium isotopes?","authors":"Xudong Wang,&nbsp;Shan Sun,&nbsp;Bin Qi,&nbsp;Shouyu Wang","doi":"10.1140/epja/s10050-025-01640-3","DOIUrl":"10.1140/epja/s10050-025-01640-3","url":null,"abstract":"<div><p>The evolutions of deformation and angular momentum orientation with rotational frequency in the <span>(pi i_{13/2})</span> bands of triaxial strongly deformed <span>(^{161, 163, 165, 167}{textrm{Lu}})</span> have been researched by the titled axis cranking model plus shell correction method. The potential energy surfaces corresponding to the deformation parameters (<span>(varepsilon )</span>, <span>(gamma )</span>) and the angular momentum orientation (<span>(theta , phi )</span>) are presented for rotational frequency <span>(hbar omega )</span> varying from 0.0 to 0.6 MeV. It is found from the calculated potential energy surfaces that the nuclear shapes are very stable at a strong triaxial deformation for Lu isotopes and the total angular momentum is favorable to align on the short axis with increasing rotational frequency. The potential energy surfaces provide highly intuitive information that the transverse wobbling motion is favorable in Lu isotopes, and such kind of calculations will be helpful to clarify the debates in wobbling motions.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166742","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}

{"title":"Comparative study of α-decay half-lives for Au, Hg, and Tl isotopes using the MGLDM, empirical formulae, and NpNn-based preformation probabilities","authors":"V. K. Anjali,&nbsp;K. P. Santhosh,&nbsp;K. P. Zuhail","doi":"10.1140/epja/s10050-025-01629-y","DOIUrl":"10.1140/epja/s10050-025-01629-y","url":null,"abstract":"<div><p>The alpha decay half-lives of Au, Hg, and Tl isotopes in the mass number range 168–198 have been investigated using the Modified Generalized Liquid Drop Model (MGLDM). In addition, we calculated the half-lives using ten different empirical formulae. The dependability of various methods is analyzed by comparing the predicted half-lives with experimental values. The MGLDM with preformation factor gives the standard deviation of 0.5923, and Modified Empirical Royer Formula (MERF) gives a value of 0.5734, which are the lowest values among model predictions and empirical formulae calculations, respectively. The New Geiger-Nuttal plot, which accommodates both favoured and unfavoured alpha transitions on a single linear curve, enhances the valuability of our model. The linear trends of the logarithmic preformation factors with the combinations of valence nucleons, shell closures, and isospin asymmetry are analysed, and this study reflects the shell effects of nuclear structure. The calculated half-lives using <span>({N}_{p}{N}_{n})</span> scheme in the framework of MGLDM are comparable with the experimental results with a small value of standard deviation.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166986","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}

{"title":"Quasicontinuum M1 (gamma ) strength as function of nuclear deformation","authors":"Magne Guttormsen","doi":"10.1140/epja/s10050-025-01642-1","DOIUrl":"10.1140/epja/s10050-025-01642-1","url":null,"abstract":"<div><p>In this investigation, we examine the mean transition probabilities of low-energy <span>(gamma )</span>-rays within the quasicontinuum excitation region. Particular emphasis is placed on the low-energy enhancement (LEE) and scissors mode (SM) structures, which are observed in the <span>(gamma )</span>-ray strength function (<span>(gamma )</span>SF). The stable isotopic chain of neodymium includes nuclei that range from nearly spherical to well-deformed shapes. Consequently, analyzing the LEE and SM structures in relation to deformation may elucidate the characteristics of these phenomena. It has been observed that the integrated measured <span>(gamma )</span>-ray strength of the LEE reaches a maximum of <span>(B(M1) approx 21 mu _N^2)</span> at a deformation of <span>(beta _2 approx 0.16)</span>, while the SM attains a maximum of <span>(B(M1) approx 8 mu _N^2)</span> at <span>(beta _2 approx 0.3)</span>. Furthermore, the two phenomena display different average <span>(gamma )</span> energies. These experimental findings suggest that the origins of the two structures arise from distinct mechanisms.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01642-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166073","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}