{"title":"Large (N_c) QCD phase diagram at (mu _B=0)","authors":"T. D. Cohen, L. Ya Glozman","doi":"10.1140/epja/s10050-024-01400-9","DOIUrl":"10.1140/epja/s10050-024-01400-9","url":null,"abstract":"<div><p>Lattice studies suggest that at zero baryon chemical potential and increasing temperature there are three characteristic regimes in QCD that are connected by smooth analytical crossovers: a hadron gas regime at <span>(T < T_{ch}sim 155)</span> MeV, an intermediate regime, called stringy fluid, at <span>(T_{ch}< T < sim 3 T_{ch})</span>, and a quark-gluon plasma regime at higher temperatures. These regimes have been interpreted to reflect different approximate symmetries and effective degrees of freedom. In the hadron gas the effective degrees of freedom are hadrons and the approximate chiral symmetry of QCD is spontaneously broken. The intermediate regime has been interpreted as lacking spontaneous chiral symmetry breaking along with the emergence of new approximate symmetry, chiral spin symmetry, that is not a symmetry of the Dirac Lagrangian, but is a symmetry of the confining part of the QCD Lagrangian. While the high temperature regime is the usual quark-gluon plasma which is often considered to reflect “deconfinement” in some way. This paper explores the behavior of these regimes of QCD as the number of colors in the theory, <span>(N_c)</span>, gets large. In the large <span>(N_c)</span> limit the theory is center-symmetric and notions of confinement and deconfinement are unambiguous. The energy density is <span>(mathcal{O}(N_c^0))</span> in the meson gas, <span>({{mathcal {O}}}(N_c^1))</span> in the intermediate regime and <span>({{mathcal {O}}}(N_c^2))</span> in the quark-gluon plasma regime. In the large <span>(N_c)</span> limit these regimes may become distinct phases separated by first order phase transitions. The intermediate phase has the peculiar feature that glueballs should exist and have properties that are unchanged from what is seen in the vacuum (up to <span>(1/N_c )</span> corrections), while the ordinary dilute gas of mesons with broken chiral symmetry disappears and approximate chiral spin symmetry should emerge.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 9","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-024-01400-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182419","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":"On interpretation of fluctuations of conserved charges at high T","authors":"T. D. Cohen, L. Ya. Glozman","doi":"10.1140/epja/s10050-024-01387-3","DOIUrl":"10.1140/epja/s10050-024-01387-3","url":null,"abstract":"<div><p>Fluctuations of conserved charges calculated on the lattice which can be measured experimentally, are well reproduced by a hadron resonanse gas model at temperatures below <span>(T_{ch} sim 155)</span> MeV and radically deviate from the hadron resonance gas predictions above the chiral restoration crossover. This behaviour is typically interpreted as an indication of deconfinement in the quark-gluon plasma regime. We present an argument that this interpretation may be too simple. The argument is based on the scaling of quantities with the number of colors: demonstration of deconfinement and QGP requires observable that is sensitive to <span>(sim N_c^2)</span> gluons while the conserved charges are sensitive only to quarks and above <span>(T_{ch})</span> scale as <span>(N_c^1)</span>. The latter scaling is consistent with the existence of an intermediate regime characterized by restored chiral symmetry and by approximate chiral spin symmetry which is a symmetry of confining interaction. In this regime the energy density, pressure and entropy density scale as <span>(N_c^1)</span>. In the large <span>(N_c)</span> limit this regime might become a distinct phase separated from the hadron gas and from QGP by phase transitions. A natural observable that associates with deconfinement and is directly sensitive to deconfined <span>(N_c^2-1)</span> gluons is the Polyakov loop; in the <span>(N_c=3)</span> world it remains very close to 0 at temperatures well above chiral crossover, reaches the value <span>(sim 0.5)</span> around <span>(sim 3T_{ch})</span> and the value close to 1 at temperatures <span>(sim 1)</span> GeV.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-024-01387-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182421","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":"Partial-wave analysis for photoproduction of pseudoscalar mesons with truncation in total angular momentum","authors":"A. Fix, I. Dementjev","doi":"10.1140/epja/s10050-024-01398-0","DOIUrl":"10.1140/epja/s10050-024-01398-0","url":null,"abstract":"<div><p>A partial-wave analysis (PWA) for the photoproduction of pseudoscalar mesons on a nucleon using truncation in total angular momentum <i>j</i> is discussed. A formalism is described that can be used for investigating discrete ambiguities. Considerable attention is devoted to the connection of this type of PWA with that based on the truncation in orbital angular momentum <i>l</i>.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-024-01398-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182423","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":"Quantifying the jet energy loss in Pb+Pb collisions at LHC","authors":"Vineet Kumar, Prashant Shukla","doi":"10.1140/epja/s10050-024-01393-5","DOIUrl":"10.1140/epja/s10050-024-01393-5","url":null,"abstract":"<div><p>In this work, we give a method to study the energy loss of jets in the medium using a variety of jet energy loss observables such as nuclear modification factor and transverse momentum asymmetry in dijets and <span>(gamma )</span>-jets in heavy ion collisions. The energy loss of jets in the medium depends mainly on the size and the properties of medium viz. temperature and is a function of energy of the jets as predicted by various models. A Monte Carlo (MC) method is employed to generate the transverse momentum and path-lengths of the initial jets that undergo energy loss. Using different scenarios of energy loss, the transverse momentum and system size dependence of nuclear modification factors and different measures of dijet momentum imbalance at energies <span>(sqrt{s_{textrm{NN}}})</span> = 2.76 TeV and 5.02 TeV and <span>(gamma )</span>-jet asymmetry at <span>(sqrt{s_{textrm{NN}}})</span> =2.76 TeV in Pb+Pb collisions are simulated. The results are compared with the measurements by ATLAS and CMS experiments as a function of transverse momentum and centrality. The study demonstrates how the system size and energy dependence of jet energy loss can be quantified using various experimental observables.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-024-01393-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182422","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}
R. Li, N. Sparveris, H. Atac, M. K. Jones, M. Paolone, Z. Akbar, M. Ali, C. Ayerbe Gayoso, V. Berdnikov, D. Biswas, M. Boer, A. Camsonne, J.-P. Chen, M. Diefenthaler, B. Duran, D. Dutta, D. Gaskell, O. Hansen, F. Hauenstein, N. Heinrich, W. Henry, T. Horn, G. M. Huber, S. Jia, S. Joosten, A. Karki, S. J. D. Kay, V. Kumar, X. Li, W. B. Li, A. H. Liyanage, D. Mack, S. Malace, P. Markowitz, M. McCaughan, Z.-E. Meziani, H. Mkrtchyan, C. Morean, M. Muhoza, A. Narayan, B. Pasquini, M. Rehfuss, B. Sawatzky, G. R. Smith, A. Smith, R. Trotta, C. Yero, X. Zheng, J. Zhou
{"title":"Pion electroproduction measurements in the nucleon resonance region","authors":"R. Li, N. Sparveris, H. Atac, M. K. Jones, M. Paolone, Z. Akbar, M. Ali, C. Ayerbe Gayoso, V. Berdnikov, D. Biswas, M. Boer, A. Camsonne, J.-P. Chen, M. Diefenthaler, B. Duran, D. Dutta, D. Gaskell, O. Hansen, F. Hauenstein, N. Heinrich, W. Henry, T. Horn, G. M. Huber, S. Jia, S. Joosten, A. Karki, S. J. D. Kay, V. Kumar, X. Li, W. B. Li, A. H. Liyanage, D. Mack, S. Malace, P. Markowitz, M. McCaughan, Z.-E. Meziani, H. Mkrtchyan, C. Morean, M. Muhoza, A. Narayan, B. Pasquini, M. Rehfuss, B. Sawatzky, G. R. Smith, A. Smith, R. Trotta, C. Yero, X. Zheng, J. Zhou","doi":"10.1140/epja/s10050-024-01391-7","DOIUrl":"10.1140/epja/s10050-024-01391-7","url":null,"abstract":"<div><p>We report new pion electroproduction measurements in the <span>(Delta (1232))</span> resonance, utilizing the SHMS - HMS magnetic spectrometers of Hall C at Jefferson Lab. The data focus on a region that exhibits a strong and rapidly changing interplay of the mesonic cloud and quark-gluon dynamics in the nucleon. The results are in reasonable agreement with models that employ pion cloud effects and chiral effective field theory calculations, but at the same time they suggest that an improvement is required to the theoretical calculations and provide valuable input that will allow their refinements. The data illustrate the potential of the magnetic spectrometers setup in Hall C towards the study the <span>(Delta (1232))</span> resonance. These first reported results will be followed by a series of measurements in Hall C, that will expand the studies of the <span>(Delta (1232))</span> resonance offering a high precision insight within a wide kinematic range from low to high momentum transfers.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182434","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":"Circular polarization measurement for individual gamma rays in capture reactions with intense pulsed neutrons","authors":"Shunsuke Endo, Ryota Abe, Hiroyuki Fujioka, Takashi Ino, Osamu Iwamoto, Nobuyuki Iwamoto, Shiori Kawamura, Atsushi Kimura, Masaaki Kitaguchi, Ryuju Kobayashi, Shoji Nakamura, Takayuki Oku, Takuya Okudaira, Mao Okuizumi, Mohamed Omer, Gerard Rovira, Tatsushi Shima, Hirohiko M. Shimizu, Toshiyuki Shizuma, Yoshitaka Taira, Shusuke Takada, Shingo Takahashi, Hiromoto Yoshikawa, Tamaki Yoshioka, Heishun Zen","doi":"10.1140/epja/s10050-024-01392-6","DOIUrl":"10.1140/epja/s10050-024-01392-6","url":null,"abstract":"<div><p>Measurements of circular polarization of <span>(gamma )</span>-ray emitted from neutron capture reactions provide valuable information for nuclear physics studies. The spin and parity of excited states can be determined by measuring the circular polarization from polarized neutron capture reactions. Furthermore, the <span>(gamma )</span>-ray circular polarization in a neutron capture resonance is crucial for studying the enhancement effect of parity nonconservation in compound nuclei. The <span>(gamma )</span>-ray circular polarization can be measured using a polarimeter based on magnetic Compton scattering. A polarimeter was constructed, and its performance indicators were evaluated using a circularly polarized <span>(gamma )</span>-ray beam. Finally, as a demonstration, the <span>(gamma )</span>-ray circular polarization was measured in <sup>32</sup>S(<span>(mathbf {text {n}})</span>,<span>(gamma )</span>)<sup>33</sup>S reactions with polarized neutrons.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182432","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}
C. Y. Guo, W. Q. Zhang, H. Huang, S. Q. Zhang, Z. H. Li, Z. Liu, H. Hua, D. W. Luo, H. Y. Wu, A. N. Andreyev, D. Seweryniak, B. Andel, S. Antalic, A. E. Barzakh, M. Block, A. Bronis, M. P. Carpenter, P. Copp, J. G. Cubiss, D. T. Doherty, P. Van Duppen, Z. Favier, F. Giacoppo, B. Kindler, F. G. Kondev, T. Lauritsen, X. Q. Li, B. Lommel, M. Al Monthery, P. Mošať, L. Ni, C. Raison, W. Reviol, G. Savard, S. Stolze, G. L. Wilson, C. Xu, J. Z. Zhang, S. Y. Zhang, Z. X. Zhou
{"title":"Spectroscopy of 187Tl: shape coexistence","authors":"C. Y. Guo, W. Q. Zhang, H. Huang, S. Q. Zhang, Z. H. Li, Z. Liu, H. Hua, D. W. Luo, H. Y. Wu, A. N. Andreyev, D. Seweryniak, B. Andel, S. Antalic, A. E. Barzakh, M. Block, A. Bronis, M. P. Carpenter, P. Copp, J. G. Cubiss, D. T. Doherty, P. Van Duppen, Z. Favier, F. Giacoppo, B. Kindler, F. G. Kondev, T. Lauritsen, X. Q. Li, B. Lommel, M. Al Monthery, P. Mošať, L. Ni, C. Raison, W. Reviol, G. Savard, S. Stolze, G. L. Wilson, C. Xu, J. Z. Zhang, S. Y. Zhang, Z. X. Zhou","doi":"10.1140/epja/s10050-024-01395-3","DOIUrl":"10.1140/epja/s10050-024-01395-3","url":null,"abstract":"<div><p>The prompt and delayed <span>(gamma )</span>-ray spectra of <sup>187</sup>Tl was studied via the <sup>142</sup>Nd(<sup>50</sup>Cr, 3<i>p</i>2<i>n</i>)<sup>187</sup>Tl fusion-evaporation reaction at a beam energy of 255 MeV. An enhanced level scheme of <sup>187</sup>Tl was established. The collective bands with one-quasiparticle configurations from the <span>(2f_{7/2})</span>, <span>(1h_{9/2})</span>, <span>(1h_{11/2})</span> and <span>(1i_{13/2})</span> orbitals and high-lying structures with possible three-quasiparticle configurations are investigated in terms of the tilted axis cranking covariant density functional theory. At low excitation energy, the rotational bands with one-quasiparticle configurations reflect coexistence of three shapes: prolate, triaxial, and oblate. The possible shapes of two microsecond isomers at high excitation energy are proposed.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182433","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":"Is there an abrupt fall of spontaneous fission half-lives in 248No and 252Rf?","authors":"I. S. Rogov, G. G. Adamian, N. V. Antonenko","doi":"10.1140/epja/s10050-024-01382-8","DOIUrl":"10.1140/epja/s10050-024-01382-8","url":null,"abstract":"<div><p>Spontaneous fission and <span>(alpha )</span> decay from the ground state of nuclei <sup>248</sup>No and <sup>252</sup>Rf are studied within the dinuclear system model. All these decay processes are considered as the evolution of a nucleus in the charge (mass) asymmetry coordinate. For the even–even and even–odd nobelium and rutherfordium isotopes, the available experimental spontaneous fission and <span>(alpha )</span>-decay half-lives of the ground state are effectively described.\u0000</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182436","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":"Erratum to: Study of spatial structures in (alpha )-cluster nuclei","authors":"V. V. Samarin","doi":"10.1140/epja/s10050-024-01379-3","DOIUrl":"10.1140/epja/s10050-024-01379-3","url":null,"abstract":"","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182435","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":"Nonlinear corrections to the momentum sum rule","authors":"G. R. Boroun","doi":"10.1140/epja/s10050-024-01348-w","DOIUrl":"10.1140/epja/s10050-024-01348-w","url":null,"abstract":"<div><p>The importance of nonlinear corrections to the momentum sum rule is investigated on the initial scale <span>(Q_{0}^2)</span>. Nonlinear corrections are found to play an indispensable role in the singlet and gluon momentum sum rule in the high-order approximations in the parton distribution function parameterizations for nucleons and light nuclei at low <i>x</i> in future colliders. In this way, we obtain a significantly different low <i>x</i> behavior of the singlet and gluon momentum sum rule at the hotspot point.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182438","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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