物理最新文献

{"title":"Interplay of intrinsic motion of partons and soft gluon emissions in Drell–Yan production studied with PYTHIA","authors":"I. Bubanja,&nbsp;H. Jung,&nbsp;N. Raičević,&nbsp;S. Taheri Monfared","doi":"10.1140/epjc/s10052-025-14066-4","DOIUrl":"10.1140/epjc/s10052-025-14066-4","url":null,"abstract":"<div><p>Understanding the intrinsic transverse momentum (intrinsic-<span>(k_textrm{T})</span>) of partons within colliding hadrons, typically modeled with a Gaussian distribution characterized by a specific width (the intrinsic-<span>(k_textrm{T})</span>width), has been an extremely challenging issue. This difficulty arises because event generators like <span>Pythia</span>8 require an intrinsic-<span>(k_textrm{T})</span> width that unexpectedly varies with collision energy, reaching unphysical values at high energies. This paper investigates the underlying physics behind this energy dependence in <span>Pythia</span>8, revealing that it arises from an interplay between two non-perturbative processes: the internal transverse motion of partons and non-perturbative soft gluon emissions. These contributions are most constrained in the production of Drell–Yan pairs with very low transverse momentum, where soft gluon effects become increasingly prominent with rising collision energy-contrary to initial expectations. Through a detailed analysis of the Sudakov form factor and its influence on intrinsic-<span>(k_textrm{T})</span> width, we clarify the observed energy scaling behavior in <span>Pythia</span>8, providing insight into a longstanding issue in parton shower modeling.\u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14066-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143740774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Deuteron gravitational form factors, generalized parton distributions, and charge density in the framework of the soft-wall AdS/QCD model","authors":"Shahin Mamedov,&nbsp;Minaya Allahverdiyeva,&nbsp;Narmin Akbarova","doi":"10.1140/epjc/s10052-025-14063-7","DOIUrl":"10.1140/epjc/s10052-025-14063-7","url":null,"abstract":"<div><p>We study gravitational deuteron form factors (GFF) and generalized parton distributions (GPDs) within the soft-wall AdS/QCD model, where deuteron is described by the bulk vector field with twist <span>(tau )</span> <span>(=)</span> 6. For finite-temperature studies, we apply the soft-wall model, which is thermalized by introducing a thermal dilaton field. The GPDs and charge density are considered in impact parameter (IP) space and at zero and finite temperatures. We plotted the temperature dependence of these quantities in the IP space and observe a decrease in their peaks as the temperature increases. The gravitational root mean square radius obtained here is close to the range given by experimental data for the mass radius and has low sensitivity to the temperature.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14063-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The Einstein Telescope standard siren simulations for f(Q) cosmologies","authors":"Xianfu Su,&nbsp;Dongze He,&nbsp;Yi Zhang","doi":"10.1140/epjc/s10052-025-14077-1","DOIUrl":"10.1140/epjc/s10052-025-14077-1","url":null,"abstract":"<div><p>To investigate the model and extra frictional effects in standard siren simulation of <i>f</i>(<i>Q</i>) cosmologies, we simulated three types of standard siren data based on different fiducial models (<span>(Lambda )</span>CDM and <i>f</i>(<i>Q</i>) models). Both effects are important in standard siren simulation. Explicitly, the <span>(f(Q)_P)</span> and <span>(f(Q)_E)</span> models need more observational data (e.g. growth factor) to further study. The <span>(f(Q)_{PE})</span> model could be ruled out by the EM data. And both the <span>(f(Q)_{HT})</span> models will be excluded by the future standard siren data.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14077-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The rotational relaxation of ro-vibrationally excited H2(1,11) in collision with N2","authors":"Jing Liu,&nbsp;Nurali Habibulla,&nbsp;Lin Mao","doi":"10.1140/epjp/s13360-025-06196-1","DOIUrl":"10.1140/epjp/s13360-025-06196-1","url":null,"abstract":"<div><p>The collisional energy relaxation behavior of the H₂(<i>v</i> = 1, <i>J</i> = 11) molecule in an H₂-N₂ mixture was investigated at 300 K using a coherent anti-Stokes Raman spectroscopy technique, focusing on its near-resonant rotation-vibration dynamics. The pressure of the H₂-N₂ mixture is maintained at 500 Torr, while the molar ratios of N₂ molecules are, respectively, adjusted to 0.2, 0.4, 0.5, 0.6, and 0.7. The H₂(1,11) molecule is selectively excited through a stimulated Raman pumping technique, and the time-resolved CARS signal is observed from the <i>J</i> ≤ 11 rotational level of H₂ molecules following collisions with N₂. The results indicate that the rotational relaxation of H₂(1,11) molecule involves both the multi-quantum relaxation process triggered by H₂-H₂ collisions and the single-quantum relaxation process via H₂-N₂ collisions. The rate coefficient for self-relaxation of H₂-H₂ collisions is (1.35 ± 0.14) × 10^–14 cm³s⁻¹, whereas the relaxation rate coefficient for H₂-N₂ collisions is (2.77 ± 0.27) × 10^–14 cm³s⁻¹. As the molar ratio of N₂ increases, the continuous single-quantum relaxation of H₂(1,11) molecules with <i>J</i> = 11 → 9 → 7 gradually becomes more pronounced. The rotational temperature of H₂ with various N₂ molar ratios is determined by the relative populations of a rotational Boltzmann distribution. When the molar ratio of N₂ is small, the rotation temperature decreases at a faster rate primarily due to the rapid multi-quantum relaxation resulting from near-resonant collisions between H₂-H₂.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 3","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726633","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":"Universal thermodynamic topological classes of black holes in a perfect fluid dark matter background","authors":"Muhammad Rizwan,&nbsp;Mubasher Jamil,&nbsp;M. Z. A. Moughal","doi":"10.1140/epjc/s10052-025-14070-8","DOIUrl":"10.1140/epjc/s10052-025-14070-8","url":null,"abstract":"<div><p>In this paper, we study the universal thermodynamic topological classes of a family of black holes in a perfect fluid dark matter (PFDM) background. Recent research on black hole thermodynamics suggests that all black holes can be cast into four universal thermodynamic classes, denoted by <span>(W^{1-})</span>, <span>(W^{0+})</span>, <span>(W^{0-})</span>, and <span>(W^{1+})</span>. Our study reveals that the Schwarzschild black hole in PFDM belongs to the <span>(W^{1-})</span> class, and the independence of black hole size is thermodynamically unstable in both the low- and high-temperature limits. The Reissner–Nordström, Kerr, and Kerr–Newman black holes in the PFDM background belong to the same universal thermodynamic class, <span>(W^{0+})</span>, which represents small-stable black holes and large-unstable black holes at low-temperature limits, whereas no black hole state exists at high temperatures. The AdS black holes behave differently when compared to their counterparts in PFDM. The Schwarzschild–AdS black hole belongs to the <span>(W^{0-})</span> class, indicating that no black hole state exists at low temperatures, but small-unstable and large-stable black hole states exist at high temperatures. Furthermore, the Kerr–AdS black hole belongs to the <span>(W^{1+})</span> class, characterized by small-stable black holes at low temperatures, large-stable black holes at high temperatures, and unstable intermediate-sized black holes at both low and high temperatures. Thus, the presence of PFDM does not affect the stability of the black hole. These findings uncover the universal topological classifications underlying black hole thermodynamics, offering profound insights into the fundamental principles of quantum gravity.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14070-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Proton spin in double-logarithmic approximation","authors":"B. I. Ermolaev","doi":"10.1140/epjc/s10052-025-14067-3","DOIUrl":"10.1140/epjc/s10052-025-14067-3","url":null,"abstract":"<div><p>Proton is a composite particle, so its spin <span>(S_P)</span> is made from the spins of the partons which the proton consists of the discrepancy between <span>(S_P= 1/2)</span> and the experimentally detected sum of the parton spins was named Proton Spin Puzzle. Solution to this problem includes formulae for the parton helicities valid in the whole range of <i>x</i>. There are approaches in the literature for calculating the helicities. As a theoretical basis they apply evolution equations of different types. Despite these equations are constructed for operating in widely different regions of <i>x</i> and account for different contributions, all of them equally well suited for solving the proton spin problem. Our explanation of this situation is that the main impact on values of the parton spin contributions should be brought not by the evolution equations themselves but by phenomenological fits for initial parton distributions. We suggest a more theoretically grounded approach to description of the parton helicities and apply it to solving the proton spin problem. It combines the total resummation of double logarithms (DL), accounting for the running <span>(alpha _s)</span> effects and DGLAP formulae, leading to expressions for the helicities valid at arbitrary <i>x</i>. As a consequence, the set of involved phenomenological parameters in our approach is minimal and its influence on the helicity behaviour is weak. We apply our approach to solve the proton spin problem in a straightforward way and make an estimate, demonstrating that the RHIC data complemented by the DL contributions from the regions of <i>x</i> beyond the RHIC scope are well compatible with the value <span>(S_P = 1/2)</span>.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14067-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Neodymium ion-doped borate-silicate glass: a thorough analysis for applications in optical and protective radiation","authors":"Aljawhara Almuqrin,&nbsp;Jamelah S. Al-Otaibi,&nbsp;Norah Alwadai,&nbsp;Badriah Albarzan,&nbsp;M. S. Shams,&nbsp;Yasser S. Rammah,&nbsp;R. A. Elsad","doi":"10.1140/epjp/s13360-025-06194-3","DOIUrl":"10.1140/epjp/s13360-025-06194-3","url":null,"abstract":"<div><p>In this study, neodymium (Nd)-doped bismuth borosilicate glasses were produced using a melting-quenching technique. The glass density rose, and molar volume fell as the Nd³⁺ ion concentration rose. The influence of Nd substitution on radiation shielding as well as optical properties was investigated. The Phy-X/PSD as well as XCOM programs are used to study radiation shielding properties in the gamma-photon energy band of 0.015: 10 MeV. As the Nd₂O₃ concentration increased, the band gap (E_OPT) levels dropped from 3.221 toward 3.051 eV during the direct transition as well as from 2.622 to 1.855 eV during the indirect transition. As Nd quantity increased, the molar refractivity rose from 19.497 to 21.106 cm³/mol and the refractive index improved from 2.50 to 2.80. The Nd₂O₃ addition to the glasses led to higher MAC and LAC values. The sample with the highest neodymium doping (Nd-1.2) had the lowest mean free path as well as half-value layer. This demonstrated how neodymium enhances glasses’ capacity to reduce photon radiation. The glass system is suggested as a shielding material in terms of photon attenuation.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 3","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726630","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":"The mixed phase quark core in massive hybrid stars","authors":"Xuhao Wu,&nbsp;Peng-Cheng Chu,&nbsp;Min Ju,&nbsp;He Liu","doi":"10.1140/epjc/s10052-025-14088-y","DOIUrl":"10.1140/epjc/s10052-025-14088-y","url":null,"abstract":"<div><p>We investigate the properties of hybrid star and the mixed phase core to explore the radius ratio of the mixed phase in hybrid star. In the context of observed massive neutron stars (NSs), we examine the internal structure, phase transitions, and the impacts of the equation of state (EOS) in maximum hybrid star. We investigate the stiffness changes in the EOS during the hadron-quark phase transition within the hybrid stars. The relativistic mean-field (RMF) model is used to describe hadronic matter, while to the represent quark matter, the Nambu–Jona–Lasinio (NJL) model is applied. We explore the strength of vector coupling in quark matter, which delays the onset density of the mixed phase and reduces the size of the mixed-phase core in a hybrid star, but does not exhibit a clear correlation with the central density. In a hybrid star with a maximum mass of approximately 2 solar masses (<span>(M_odot )</span>), a mixed-phase core of <span>(sim )</span> 5 km may exist, comprising about <span>(40%)</span> of the total radius. However, our results do not support the existence of a sizable quark core containing the mixed phase (<span>(R_mathrm{{MP}}&gt;1/2~R_mathrm{{total}})</span>) for the maximum-mass hybrid star or for a 2 <span>(M_odot )</span> massive star.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14088-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Genuine four-partite Bell nonlocality in the curved spacetime","authors":"Guang-Wei Mi,&nbsp;Xiaofen Huang,&nbsp;Shao-Ming Fei,&nbsp;Tinggui Zhang","doi":"10.1140/epjc/s10052-025-14076-2","DOIUrl":"10.1140/epjc/s10052-025-14076-2","url":null,"abstract":"<div><p>The quantum Bell nonlocality plays a crucial role in quantum information processing. In this paper, we first obtain the quantitative analytical expression of the genuine four-partite Bell nonlocality of any 4-qubit quantum state. Then, we investigate and derive the genuine four-partite nonlocalities in the background of the Schwarzschild black hole and the Schwarzschild–de Sitter spacetime. In the Schwarzschild black hole, it is shown that the Hawking effect destroys the accessible genuine four-partite nonlocality whif the Hawking effect of the Schwarzschild–de Sitter spacetime on the genuine four-partite nonlocality of massless Dirac fields.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14076-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Frozen Bardeen-Dirac stars and light ball","authors":"Long-Xing Huang,&nbsp;Shi-Xian Sun,&nbsp;Yong-Qiang Wang","doi":"10.1140/epjc/s10052-025-13929-0","DOIUrl":"10.1140/epjc/s10052-025-13929-0","url":null,"abstract":"<div><p>In this paper, we study solutions of a static spherically symmetric system, which is composed of the coupling with the Bardeen action and two Dirac fields. For the case where only the Bardeen action is present, the magnetic charge <i>q</i> can be infinite, then when the magnetic charge is greater than a certain value <span>(q_b)</span>, there exists a black hole solution, which is called the Bardeen black hole (BBH). However, if the Dirac field is introduced, we find that the magnetic charge can only be smaller than the critical value <span>(q_b)</span>, in which there is no black hole solution. Moreover, in the region <span>(q&lt;q_b)</span>, we find that if the magnetic charge exceeds another critical value <span>(q_c)</span> (i.e., <span>(q_c&lt;q&lt;q_b)</span>), the frequency of the Dirac field can approach zero, and the solution where a critical horizon appears is similar to an extremal black hole outside the critical horizon but has a nonsingular interior. The Dirac fields are also almost concentrated within it. In fact, this is a frozen star solution, we call such solutions frozen Bardeen-Dirac stars (FBDSs). We analyze the light rings of FBDSs and find that there exists a “true” light ring outside the critical horizon, but inside it, the velocity of photons is very close to zero, which leads to the formation of a “light ball” inside the critical horizon.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13929-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}