Pub Date : 2024-09-17DOI: 10.1088/1361-6471/ad75ac
S S Agaev, K Azizi, B Barsbay and H Sundu
Properties of doubly charged scalar tetraquarks are investigated in the framework of the Quantum Chromodynamic (QCD) sum rule method. We model them as diquark–antidiquark states X1 and X2 built of axial-vector and pseudoscalar diquarks, respectively. The masses and current couplings of these particles are computed using the QCD two-point sum rule method. Results m1 = (12715 ± 80) MeV and m2 = (13370 ± 95) MeV obtained for the masses of these particles are used to determine their kinematically allowed decay modes. The full width Γ1 of the state X1 is evaluated by taking into account its strong decays to mesons , and . The processes , and are employed to estimate Γ2. Predictions obtained for the full widths Γ1 = (63 ± 12) MeV and Γ2 = (79 ± 14) MeV of these structures and their masses may be utilized in experimental studies of fully heavy resonances.
{"title":"Scalar exotic mesons bb c ¯ ...","authors":"S S Agaev, K Azizi, B Barsbay and H Sundu","doi":"10.1088/1361-6471/ad75ac","DOIUrl":"https://doi.org/10.1088/1361-6471/ad75ac","url":null,"abstract":"Properties of doubly charged scalar tetraquarks are investigated in the framework of the Quantum Chromodynamic (QCD) sum rule method. We model them as diquark–antidiquark states X1 and X2 built of axial-vector and pseudoscalar diquarks, respectively. The masses and current couplings of these particles are computed using the QCD two-point sum rule method. Results m1 = (12715 ± 80) MeV and m2 = (13370 ± 95) MeV obtained for the masses of these particles are used to determine their kinematically allowed decay modes. The full width Γ1 of the state X1 is evaluated by taking into account its strong decays to mesons , and . The processes , and are employed to estimate Γ2. Predictions obtained for the full widths Γ1 = (63 ± 12) MeV and Γ2 = (79 ± 14) MeV of these structures and their masses may be utilized in experimental studies of fully heavy resonances.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"9 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142261260","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}
Pub Date : 2024-09-08DOI: 10.1088/1361-6471/ad6fbc
Xiong-Hui Cao, Meng-Lin Du and Feng-Kun Guo
Hidden-charm exotic hadrons will be searched for and investigated at future electron–ion colliders. For instance, the X(3872) can be produced through the exclusive process γp → X(3872)p. The vector meson dominance model has been commonly employed in estimating the cross sections of such processes. However, the coupled-channel production mechanism through open-charm meson-baryon intermediate states may play a crucial role. To assess the significance of such contributions, we estimate the cross section of the γp → X(3872)p reaction assuming the coupled-channel mechanism. For energies near the threshold, the total cross section is predicted to be of tens of nanobarns for γp → X(3872)p, which can be measured at future experimental facilities. Furthermore, the open-charm coupled-channel mechanism leads to a distinct line shape of the total cross section that can be utilized to reveal the production dynamics.
{"title":"Photoproduction of the X(3872) beyond vector meson dominance: the open-charm coupled-channel mechanism","authors":"Xiong-Hui Cao, Meng-Lin Du and Feng-Kun Guo","doi":"10.1088/1361-6471/ad6fbc","DOIUrl":"https://doi.org/10.1088/1361-6471/ad6fbc","url":null,"abstract":"Hidden-charm exotic hadrons will be searched for and investigated at future electron–ion colliders. For instance, the X(3872) can be produced through the exclusive process γp → X(3872)p. The vector meson dominance model has been commonly employed in estimating the cross sections of such processes. However, the coupled-channel production mechanism through open-charm meson-baryon intermediate states may play a crucial role. To assess the significance of such contributions, we estimate the cross section of the γp → X(3872)p reaction assuming the coupled-channel mechanism. For energies near the threshold, the total cross section is predicted to be of tens of nanobarns for γp → X(3872)p, which can be measured at future experimental facilities. Furthermore, the open-charm coupled-channel mechanism leads to a distinct line shape of the total cross section that can be utilized to reveal the production dynamics.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193092","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}
Pub Date : 2024-09-04DOI: 10.1088/1361-6471/ad704a
A Capolupo, A Quaranta
We reveal the presence of a new source of axial current due to the condensed vacuum generated by the spin–spin interaction. To show this, we consider a quartic Dirac Lagrangian containing a spin–spin interaction term, possibly originating from torsion in Einstein–Cartan-like theories. We use a mean field approach to analyze the quantized theory. We show that the diagonalization of the field Hamiltonian defines a new vacuum state, energetically favored with respect to the free vacuum. Such a vacuum, which is a condensate of particle-antiparticle pairs, is characterized by a nontrivial expectation value of the axial current operator. The new source of axial current, here obtained, can have effects both at the atomic level and at the astrophysical–cosmological level depending on the origin of the spin–spin interaction term. The condensate spontaneously breaks Lorentz symmetry, therefore it implies the possibility of CPT violation in the early universe. Furthermore the condensate induces a new source term in the gravitational field equations and may affect the dark sector of the Universe at cosmological level.
{"title":"Fermion condensates induced by axial interactions and cosmological implications","authors":"A Capolupo, A Quaranta","doi":"10.1088/1361-6471/ad704a","DOIUrl":"https://doi.org/10.1088/1361-6471/ad704a","url":null,"abstract":"We reveal the presence of a new source of axial current due to the condensed vacuum generated by the spin–spin interaction. To show this, we consider a quartic Dirac Lagrangian containing a spin–spin interaction term, possibly originating from torsion in Einstein–Cartan-like theories. We use a mean field approach to analyze the quantized theory. We show that the diagonalization of the field Hamiltonian defines a new vacuum state, energetically favored with respect to the free vacuum. Such a vacuum, which is a condensate of particle-antiparticle pairs, is characterized by a nontrivial expectation value of the axial current operator. The new source of axial current, here obtained, can have effects both at the atomic level and at the astrophysical–cosmological level depending on the origin of the spin–spin interaction term. The condensate spontaneously breaks Lorentz symmetry, therefore it implies the possibility of CPT violation in the early universe. Furthermore the condensate induces a new source term in the gravitational field equations and may affect the dark sector of the Universe at cosmological level.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"12 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193094","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}
Pub Date : 2024-09-04DOI: 10.1088/1361-6471/ad6fbd
Z Elekes, V Panin, T R Rodríguez, K Sieja, D S Ahn, A Al-Adili, H Baba, A I Stefanescu, K J Cook, Cs Dósa, N Fukuda, J Gao, J Gibelin, K I Hahn, Z Halász, S W Huang, T Isobe, M M Juhász, D Kim, T Kobayashi, Y Kondo, Z Korkulu, A Kurihara, I Kuti, H Miki, K Miki, T Motobayashi, H Otsu, A Saastamoinen, M Sasano, H Sato, N H Shadhin, T Shimada, Y Shimizu, I C Stefanescu, L Stuhl, H Suzuki, H Takeda, Y Togano, T Tomai, L Trache, D Tudor, T Uesaka, Y Utsuki, H Wang, A Yasuda, K Yoneda, Y Yoshitome
The low-energy states of the proton-rich nucleus 62Ge were studied by the multinucleon knock-out reaction 67Se(12C,X)62Ge using a 12C target. The analysis of the Doppler-corrected singles spectrum of the γ rays showed two transitions at 744(20) keV and 948(17) keV, which were found to be in coincidence with each other, forming a cascade and establishing two states at 948(17) keV and 1692(26) keV. The 744 keV transition was detected for the first time, and based on a comparison of the experimental data to shell-model and symmetry-conserving-configuration-mixing-model calculations, it connects the second and first 2+ levels. The beyond-mean-field model suggests that these states belong to two different bands with triaxial features and similar deformation.
{"title":"Low-lying excited states in 62Ge investigated by multinucleon knock-out reaction","authors":"Z Elekes, V Panin, T R Rodríguez, K Sieja, D S Ahn, A Al-Adili, H Baba, A I Stefanescu, K J Cook, Cs Dósa, N Fukuda, J Gao, J Gibelin, K I Hahn, Z Halász, S W Huang, T Isobe, M M Juhász, D Kim, T Kobayashi, Y Kondo, Z Korkulu, A Kurihara, I Kuti, H Miki, K Miki, T Motobayashi, H Otsu, A Saastamoinen, M Sasano, H Sato, N H Shadhin, T Shimada, Y Shimizu, I C Stefanescu, L Stuhl, H Suzuki, H Takeda, Y Togano, T Tomai, L Trache, D Tudor, T Uesaka, Y Utsuki, H Wang, A Yasuda, K Yoneda, Y Yoshitome","doi":"10.1088/1361-6471/ad6fbd","DOIUrl":"https://doi.org/10.1088/1361-6471/ad6fbd","url":null,"abstract":"The low-energy states of the proton-rich nucleus <sup>62</sup>Ge were studied by the multinucleon knock-out reaction <sup>67</sup>Se(<sup>12</sup>C,X)<sup>62</sup>Ge using a <sup>12</sup>C target. The analysis of the Doppler-corrected singles spectrum of the <italic toggle=\"yes\">γ</italic> rays showed two transitions at 744(20) keV and 948(17) keV, which were found to be in coincidence with each other, forming a cascade and establishing two states at 948(17) keV and 1692(26) keV. The 744 keV transition was detected for the first time, and based on a comparison of the experimental data to shell-model and symmetry-conserving-configuration-mixing-model calculations, it connects the second and first 2<sup>+</sup> levels. The beyond-mean-field model suggests that these states belong to two different bands with triaxial features and similar deformation.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"2012 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193122","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6471/ad6a2a
L Csedreki, Gy Gyürky, D Rapagnani, G F Ciani, M Aliotta, C Ananna, L Barbieri, F Barile, D Bemmerer, A Best, A Boeltzig, C Broggini, C G Bruno, A Caciolli, F Casaburo, F Cavanna, P Colombetti, A Compagnucci, P Corvisiero, T Davinson, R Depalo, A Di Leva, Z Elekes, F Ferraro, A Formicola, Zs Fülöp, G Gervino, A Guglielmetti, C Gustavino, G Imbriani, M Junker, M Lugaro, P Marigo, J Marsh, E Masha, R Menegazzo, V Paticchio, R Perrino, D Piatti, P Prati, D Robb, L Schiavulli, R S Sidhu, J Skowronski, O Straniero, T Szücs, S Zavatarelli
The 13C(α,n)16O reaction is the main neutron source of the s-process taking place in thermally pulsing AGB stars and it is one of the main candidate sources of neutrons for the i-process in the astrophysical sites proposed so far. Therefore, its rate is crucial to understand the production of the nuclei heavier than iron in the Universe. For the first time, the LUNA collaboration was able to measure the 13C(α,n)16O cross section at Ec.m. = 0.23−0.3 MeV drastically reducing the uncertainty of the S(E)-factor in the astrophysically relevant energy range. In this paper, we provide details and critical thoughts about the LUNA measurement and compare them with the current understanding of the 13C(α,n)16O reaction in view of future prospect for higher energy measurements. The two very recent results (from the University of Notre Dame and the JUNA collaboration) published after the LUNA data represent an important step forward. There is, however, still room for a lot of improvement in the experimental study of the 13C(α,n)16O reaction, as emphasized in the present manuscript. We conclude that to provide significantly better constraints on the low-energy extrapolation, experimental data need to be provided over a wide energy range, which overlaps with the energy range of current measurements. Furthermore, future experiments need to focus on the proper target characterisation, the determination of neutron detection efficiency having more nuclear physics input, such as angular distribution of the 13C(α,n)16O reaction below Eα < 0.8 MeV and study of nuclear properties of monoenergetic neutron sources and/or via the study of sharp resonances of 13C(α,n)16O. Moreover, comprehensive, multichannel R-matrix analysis with a proper estimate of uncertainty budget of experimental data are still required.
13C(α,n)16O反应是发生在热脉动AGB恒星中的s过程的主要中子源，也是迄今为止提出的天体物理场所中i过程的主要候选中子源之一。因此，它的速率对于了解宇宙中比铁更重的原子核的产生至关重要。LUNA 合作小组首次测量了 Ec.m. = 0.23-0.3 MeV 的 13C(α,n)16O 截面，大大降低了天体物理学相关能量范围内 S(E) 因子的不确定性。在本文中，我们提供了有关 LUNA 测量的细节和批判性思考，并将其与目前对 13C(α,n)16O反应的理解进行了比较，以展望未来更高能量测量的前景。在 LUNA 数据之后发表的两个最新结果（来自圣母大学和 JUNA 合作组织）代表了向前迈出的重要一步。然而，正如本手稿所强调的，13C(α,n)16O 反应的实验研究仍有很大的改进空间。我们的结论是，要想对低能外推法提供明显更好的约束，需要提供宽能量范围的实验数据，这与当前测量的能量范围是重叠的。此外，未来的实验还需要关注正确的目标特征描述，确定中子探测效率和更多的核物理输入，如 Eα < 0.8 MeV 以下 13C(α,n)16O 反应的角度分布，以及研究单能量中子源的核特性和/或通过研究 13C(α,n)16O 的尖锐共振。此外，还需要进行全面的多通道 R 矩阵分析，并对实验数据的不确定性预算进行适当估算。
{"title":"Status and future directions for direct cross-section measurements of the 13C(a,n)16O reaction for astrophysics","authors":"L Csedreki, Gy Gyürky, D Rapagnani, G F Ciani, M Aliotta, C Ananna, L Barbieri, F Barile, D Bemmerer, A Best, A Boeltzig, C Broggini, C G Bruno, A Caciolli, F Casaburo, F Cavanna, P Colombetti, A Compagnucci, P Corvisiero, T Davinson, R Depalo, A Di Leva, Z Elekes, F Ferraro, A Formicola, Zs Fülöp, G Gervino, A Guglielmetti, C Gustavino, G Imbriani, M Junker, M Lugaro, P Marigo, J Marsh, E Masha, R Menegazzo, V Paticchio, R Perrino, D Piatti, P Prati, D Robb, L Schiavulli, R S Sidhu, J Skowronski, O Straniero, T Szücs, S Zavatarelli","doi":"10.1088/1361-6471/ad6a2a","DOIUrl":"https://doi.org/10.1088/1361-6471/ad6a2a","url":null,"abstract":"The <sup>13</sup>C(<italic toggle=\"yes\">α</italic>,<italic toggle=\"yes\">n</italic>)<sup>16</sup>O reaction is the main neutron source of the <italic toggle=\"yes\">s</italic>-process taking place in thermally pulsing AGB stars and it is one of the main candidate sources of neutrons for the <italic toggle=\"yes\">i</italic>-process in the astrophysical sites proposed so far. Therefore, its rate is crucial to understand the production of the nuclei heavier than iron in the Universe. For the first time, the LUNA collaboration was able to measure the <sup>13</sup>C(<italic toggle=\"yes\">α</italic>,<italic toggle=\"yes\">n</italic>)<sup>16</sup>O cross section at <italic toggle=\"yes\">E</italic>\u0000<sub>c.m.</sub> = 0.23−0.3 MeV drastically reducing the uncertainty of the <italic toggle=\"yes\">S</italic>(<italic toggle=\"yes\">E</italic>)-factor in the astrophysically relevant energy range. In this paper, we provide details and critical thoughts about the LUNA measurement and compare them with the current understanding of the <sup>13</sup>C(<italic toggle=\"yes\">α</italic>,<italic toggle=\"yes\">n</italic>)<sup>16</sup>O reaction in view of future prospect for higher energy measurements. The two very recent results (from the University of Notre Dame and the JUNA collaboration) published after the LUNA data represent an important step forward. There is, however, still room for a lot of improvement in the experimental study of the <sup>13</sup>C(<italic toggle=\"yes\">α</italic>,<italic toggle=\"yes\">n</italic>)<sup>16</sup>O reaction, as emphasized in the present manuscript. We conclude that to provide significantly better constraints on the low-energy extrapolation, experimental data need to be provided over a wide energy range, which overlaps with the energy range of current measurements. Furthermore, future experiments need to focus on the proper target characterisation, the determination of neutron detection efficiency having more nuclear physics input, such as angular distribution of the <sup>13</sup>C(<italic toggle=\"yes\">α</italic>,<italic toggle=\"yes\">n</italic>)<sup>16</sup>O reaction below <italic toggle=\"yes\">E</italic>\u0000<sub>\u0000<italic toggle=\"yes\">α</italic>\u0000</sub> < 0.8 MeV and study of nuclear properties of monoenergetic neutron sources and/or via the study of sharp resonances of <sup>13</sup>C(<italic toggle=\"yes\">α</italic>,<italic toggle=\"yes\">n</italic>)<sup>16</sup>O. Moreover, comprehensive, multichannel <italic toggle=\"yes\">R</italic>-matrix analysis with a proper estimate of uncertainty budget of experimental data are still required.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"24 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193123","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}
Pub Date : 2024-08-27DOI: 10.1088/1361-6471/ad6c66
S Priyanka, A Chauhan, M S Mehta, M Bhuyan
The ground state properties of Z = 125 and 126 nuclei are investigated, taking the isotopic series from the proton to neutron drip-lines. This analysis uses the relativistic mean-field approach with NL3 and the Relativistic-Hartree–Bogoliubov model with DD-ME2 parameterization. The bulk properties under examination include the binding energy per nucleon, the neutron separation energies, the differential variation of the separation energy, the quadrupole deformation parameter β2, and the single-particle energy. We observed the stability at N = 172 and 184 over the isotopic chain for both parameter sets. The quadrupole deformation parameter reveals a shape transition from prolate to spherical and back to prolate with mass number. No signature of a super- and/or hyper-deformed structure is found over the isotopic chain. Furthermore, the analysis is extended to examine the bubble structure, revealing a bubble/semi-bubble structure for a few neutron-rich isotopes.
研究了 Z = 125 和 126 原子核的基态性质，从质子到中子滴线的同位素序列。分析采用了带有 NL3 的相对论均场方法和带有 DD-ME2 参数化的相对论-哈特里-波哥留布夫模型。所研究的体特性包括每个核子的结合能、中子分离能、分离能的微分变化、四极变形参数β2和单粒子能。我们观察到在 N = 172 和 184 时，两组参数在同位素链上的稳定性。四极子形变参数显示出随着质量数的增加，形状从凸形过渡到球形，再返回到凸形。在同位素链上没有发现超变形和/或超变形结构的特征。此外，分析还扩展到了对气泡结构的研究，揭示了少数富中子同位素的气泡/半气泡结构。
{"title":"Ground state properties and bubble structure of the isotopic chains of Z = 125 and 126 using the relativistic mean-field formalism","authors":"S Priyanka, A Chauhan, M S Mehta, M Bhuyan","doi":"10.1088/1361-6471/ad6c66","DOIUrl":"https://doi.org/10.1088/1361-6471/ad6c66","url":null,"abstract":"The ground state properties of <italic toggle=\"yes\">Z</italic> = 125 and 126 nuclei are investigated, taking the isotopic series from the proton to neutron drip-lines. This analysis uses the relativistic mean-field approach with NL3 and the Relativistic-Hartree–Bogoliubov model with DD-ME2 parameterization. The bulk properties under examination include the binding energy per nucleon, the neutron separation energies, the differential variation of the separation energy, the quadrupole deformation parameter <italic toggle=\"yes\">β</italic>\u0000<sub>2</sub>, and the single-particle energy. We observed the stability at <italic toggle=\"yes\">N</italic> = 172 and 184 over the isotopic chain for both parameter sets. The quadrupole deformation parameter reveals a shape transition from prolate to spherical and back to prolate with mass number. No signature of a super- and/or hyper-deformed structure is found over the isotopic chain. Furthermore, the analysis is extended to examine the bubble structure, revealing a bubble/semi-bubble structure for a few neutron-rich isotopes.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"140 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193124","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}
Pub Date : 2024-08-27DOI: 10.1088/1361-6471/ad6a2b
Jean-François Paquet
Heavy-ion collisions provide a window into the properties of many-body systems of deconfined quarks and gluons. Understanding the collective properties of quarks and gluons is possible by comparing models of heavy-ion collisions to measurements of the distribution of particles produced at the end of the collisions. These model-to-data comparisons are extremely challenging, however, because of the complexity of the models, the large amount of experimental data, and their uncertainties. Bayesian inference provides a rigorous statistical framework to constrain the properties of nuclear matter by systematically comparing models and measurements. This review covers model emulation and Bayesian methods as applied to model-to-data comparisons in heavy-ion collisions. Replacing the model outputs (observables) with Gaussian process emulators is key to the Bayesian approach currently used in the field, and both current uses of emulators and related recent developments are reviewed. The general principles of Bayesian inference are then discussed along with other Bayesian methods, followed by a systematic comparison of seven recent Bayesian analyses that studied quark-gluon plasma properties, such as the shear and bulk viscosities. The latter comparison is used to illustrate sources of differences in analyses, and what it can teach us for future studies.
{"title":"Applications of emulation and Bayesian methods in heavy-ion physics","authors":"Jean-François Paquet","doi":"10.1088/1361-6471/ad6a2b","DOIUrl":"https://doi.org/10.1088/1361-6471/ad6a2b","url":null,"abstract":"Heavy-ion collisions provide a window into the properties of many-body systems of deconfined quarks and gluons. Understanding the collective properties of quarks and gluons is possible by comparing models of heavy-ion collisions to measurements of the distribution of particles produced at the end of the collisions. These model-to-data comparisons are extremely challenging, however, because of the complexity of the models, the large amount of experimental data, and their uncertainties. Bayesian inference provides a rigorous statistical framework to constrain the properties of nuclear matter by systematically comparing models and measurements. This review covers model emulation and Bayesian methods as applied to model-to-data comparisons in heavy-ion collisions. Replacing the model outputs (observables) with Gaussian process emulators is key to the Bayesian approach currently used in the field, and both current uses of emulators and related recent developments are reviewed. The general principles of Bayesian inference are then discussed along with other Bayesian methods, followed by a systematic comparison of seven recent Bayesian analyses that studied quark-gluon plasma properties, such as the shear and bulk viscosities. The latter comparison is used to illustrate sources of differences in analyses, and what it can teach us for future studies.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"75 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193126","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}
Pub Date : 2024-08-21DOI: 10.1088/1361-6471/ad633a
Paul-Gerhard Reinhard, Jared O’Neal, Stefan M Wild, Witold Nazarewicz
The Fayans energy density functional (EDF) has been very successful in describing global nuclear properties (binding energies, charge radii, and especially differences of radii) within nuclear density functional theory. In a recent study, supervised machine learning methods were used to calibrate the Fayans EDF. Building on this experience, in this work we explore the effect of adding isovector pairing terms, which are responsible for different proton and neutron pairing fields, by comparing a 13D model without the isovector pairing term against the extended 14D model. At the heart of the calibration is a carefully selected heterogeneous dataset of experimental observables representing ground-state properties of spherical even–even nuclei. To quantify the impact of the calibration dataset on model parameters and the importance of the new terms, we carry out advanced sensitivity and correlation analysis on both models. The extension to 14D improves the overall quality of the model by about 30%. The enhanced degrees of freedom of the 14D model reduce correlations between model parameters and enhance sensitivity.
{"title":"Extended Fayans energy density functional: optimization and analysis","authors":"Paul-Gerhard Reinhard, Jared O’Neal, Stefan M Wild, Witold Nazarewicz","doi":"10.1088/1361-6471/ad633a","DOIUrl":"https://doi.org/10.1088/1361-6471/ad633a","url":null,"abstract":"The Fayans energy density functional (EDF) has been very successful in describing global nuclear properties (binding energies, charge radii, and especially differences of radii) within nuclear density functional theory. In a recent study, supervised machine learning methods were used to calibrate the Fayans EDF. Building on this experience, in this work we explore the effect of adding isovector pairing terms, which are responsible for different proton and neutron pairing fields, by comparing a 13D model without the isovector pairing term against the extended 14D model. At the heart of the calibration is a carefully selected heterogeneous dataset of experimental observables representing ground-state properties of spherical even–even nuclei. To quantify the impact of the calibration dataset on model parameters and the importance of the new terms, we carry out advanced sensitivity and correlation analysis on both models. The extension to 14D improves the overall quality of the model by about 30%. The enhanced degrees of freedom of the 14D model reduce correlations between model parameters and enhance sensitivity.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"58 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193127","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}
In this work, we explore the possibility of the <italic toggle="yes">n</italic>–<inline-formula> <tex-math> <?CDATA $bar{n}$?> </tex-math> <mml:math overflow="scroll"><mml:mover accent="true"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math> <inline-graphic xlink:href="jpgad66efieqn1.gif" xlink:type="simple"></inline-graphic> </inline-formula> oscillation accompanied by CP-violation in the presence of magnetic fields. The <italic toggle="yes">n</italic>–<inline-formula> <tex-math> <?CDATA $bar{n}$?> </tex-math> <mml:math overflow="scroll"><mml:mover accent="true"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math> <inline-graphic xlink:href="jpgad66efieqn2.gif" xlink:type="simple"></inline-graphic> </inline-formula> oscillation, which violates the baryon number (<inline-formula> <tex-math> <?CDATA ${ mathcal B }$?> </tex-math> <mml:math overflow="scroll"><mml:mi mathvariant="script">B</mml:mi></mml:math> <inline-graphic xlink:href="jpgad66efieqn3.gif" xlink:type="simple"></inline-graphic> </inline-formula>) by two units (<inline-formula> <tex-math> <?CDATA $| {rm{Delta }}{ mathcal B }| =2$?> </tex-math> <mml:math overflow="scroll"><mml:mo stretchy="false">∣</mml:mo><mml:mi mathvariant="normal">Δ</mml:mi><mml:mi mathvariant="script">B</mml:mi><mml:mo stretchy="false">∣</mml:mo><mml:mo>=</mml:mo><mml:mn>2</mml:mn></mml:math> <inline-graphic xlink:href="jpgad66efieqn4.gif" xlink:type="simple"></inline-graphic> </inline-formula>), can originate from the mixing between the neutron (<italic toggle="yes">n</italic>) and the neutral elementary particle (<italic toggle="yes">η</italic>) and may give rise to non-trivial physical consequences that can be testable in future experiments. We show that the probability of the <italic toggle="yes">n</italic>–<inline-formula> <tex-math> <?CDATA $bar{n}$?> </tex-math> <mml:math overflow="scroll"><mml:mover accent="true"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math> <inline-graphic xlink:href="jpgad66efieqn5.gif" xlink:type="simple"></inline-graphic> </inline-formula> oscillation can be greatly enhanced by properly adjusting the magnetic field. In particular, the peak values of the oscillation probability in the presence of resonance magnetic fields can be 8–10 orders of magnitude higher than that in the absence of magnetic fields. We point out that there might not be sizable CP-violating effects in the <italic toggle="yes">n</italic>–<inline-formula> <tex-math> <?CDATA $bar{n}$?> </tex-math> <mml:math overflow="scroll"><mml:mover accent="true"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math> <inline-graphic xlink:href="jpgad66efieqn6.gif" xlink:type="simple"></inline-graphic> </inline-formula> oscillation unless the mass of <italic toggle="yes">η</italic> is close to the mass of the neutron. We also analyze
{"title":"Neutron–antineutron oscillation accompanied by CP-violation in magnetic fields","authors":"Yongliang Hao, Kamphamba Sokalao Nyirenda, Zhenwei Chen","doi":"10.1088/1361-6471/ad66ef","DOIUrl":"https://doi.org/10.1088/1361-6471/ad66ef","url":null,"abstract":"In this work, we explore the possibility of the <italic toggle=\"yes\">n</italic>–<inline-formula>\u0000<tex-math>\u0000<?CDATA $bar{n}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mover accent=\"true\"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math>\u0000<inline-graphic xlink:href=\"jpgad66efieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> oscillation accompanied by CP-violation in the presence of magnetic fields. The <italic toggle=\"yes\">n</italic>–<inline-formula>\u0000<tex-math>\u0000<?CDATA $bar{n}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mover accent=\"true\"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math>\u0000<inline-graphic xlink:href=\"jpgad66efieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> oscillation, which violates the baryon number (<inline-formula>\u0000<tex-math>\u0000<?CDATA ${ mathcal B }$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"script\">B</mml:mi></mml:math>\u0000<inline-graphic xlink:href=\"jpgad66efieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>) by two units (<inline-formula>\u0000<tex-math>\u0000<?CDATA $| {rm{Delta }}{ mathcal B }| =2$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mo stretchy=\"false\">∣</mml:mo><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:mi mathvariant=\"script\">B</mml:mi><mml:mo stretchy=\"false\">∣</mml:mo><mml:mo>=</mml:mo><mml:mn>2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"jpgad66efieqn4.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>), can originate from the mixing between the neutron (<italic toggle=\"yes\">n</italic>) and the neutral elementary particle (<italic toggle=\"yes\">η</italic>) and may give rise to non-trivial physical consequences that can be testable in future experiments. We show that the probability of the <italic toggle=\"yes\">n</italic>–<inline-formula>\u0000<tex-math>\u0000<?CDATA $bar{n}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mover accent=\"true\"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math>\u0000<inline-graphic xlink:href=\"jpgad66efieqn5.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> oscillation can be greatly enhanced by properly adjusting the magnetic field. In particular, the peak values of the oscillation probability in the presence of resonance magnetic fields can be 8–10 orders of magnitude higher than that in the absence of magnetic fields. We point out that there might not be sizable CP-violating effects in the <italic toggle=\"yes\">n</italic>–<inline-formula>\u0000<tex-math>\u0000<?CDATA $bar{n}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mover accent=\"true\"><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:math>\u0000<inline-graphic xlink:href=\"jpgad66efieqn6.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> oscillation unless the mass of <italic toggle=\"yes\">η</italic> is close to the mass of the neutron. We also analyze ","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"26 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193125","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}
Pub Date : 2024-08-13DOI: 10.1088/1361-6471/ad66ed
G Dallabona, P G de Oliveira, O A Battistel
We present a detailed investigation of the anomalous gravitational amplitude in a simple two-dimensional model with Weyl fermions. We employ a mathematical strategy that completely avoids any regularization prescription for handling divergent perturbative amplitudes. This strategy relies solely on the validity of the linearity of the integration operation and avoids modifying the amplitudes during intermediate calculations, unlike studies using regularization methods. Additionally, we adopt arbitrary routings for internal loop momenta, representing the most general analysis scenario. As expected, we show that surface terms play a crucial role in both preserving the symmetry properties of the amplitude and ensuring the mathematical consistency of the results. Notably, our final perturbative amplitude can be converted into the form obtained using any specific regularization prescription. We consider three common scenarios, one of which recovers the traditional results for gravitational anomalies. However, we demonstrate that this scenario inevitably breaks the linearity of integration, leading to an undesirable mathematical situation. This clean and transparent conclusion, enabled by the general nature of our strategy, would not be apparent in similar studies using regularization techniques.
{"title":"Ward identities in a two-dimensional gravitational model: anomalous amplitude revisited using a completely regularization-independent mathematical strategy","authors":"G Dallabona, P G de Oliveira, O A Battistel","doi":"10.1088/1361-6471/ad66ed","DOIUrl":"https://doi.org/10.1088/1361-6471/ad66ed","url":null,"abstract":"We present a detailed investigation of the anomalous gravitational amplitude in a simple two-dimensional model with Weyl fermions. We employ a mathematical strategy that completely avoids any regularization prescription for handling divergent perturbative amplitudes. This strategy relies solely on the validity of the linearity of the integration operation and avoids modifying the amplitudes during intermediate calculations, unlike studies using regularization methods. Additionally, we adopt arbitrary routings for internal loop momenta, representing the most general analysis scenario. As expected, we show that surface terms play a crucial role in both preserving the symmetry properties of the amplitude and ensuring the mathematical consistency of the results. Notably, our final perturbative amplitude can be converted into the form obtained using any specific regularization prescription. We consider three common scenarios, one of which recovers the traditional results for gravitational anomalies. However, we demonstrate that this scenario inevitably breaks the linearity of integration, leading to an undesirable mathematical situation. This clean and transparent conclusion, enabled by the general nature of our strategy, would not be apparent in similar studies using regularization techniques.","PeriodicalId":16766,"journal":{"name":"Journal of Physics G: Nuclear and Particle Physics","volume":"396 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142193130","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}
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