Peer Revenue Publish or profit

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Nuclear Experiment

nucl-ex Watch Nuclear Experiment

Wednesday 14 October · still arriving

Nuclear Experiment

Physics with Radioactive Ion Beams at the Nuclear Science Laboratory

W.S. Porter, D.W. Bardayan, M. Brodeur et al. (+13 more)

The University of Notre Dame is home to a rich history of nuclear science efforts, including some of the earliest developments in the production and creation of radioactive ion beams (RIBs). The resulting TwinSol facility stands as the longest continuously-operating RIB facility in the United States, and has enabled a wide range of experimental efforts in nuclear structure, astrophysics and fundamental symmetries through in-flight RIBs one to two nucleons from stability. A recent upgrade to TwinSol via a third solenoid constituted the founding of the TriSol facility, which provides cleaner, better-focused RIBs to downstream experiments. In this paper, we present a summary of RIB science at the Nuclear Science Laboratory (NSL) with both TwinSol and TriSol and discuss recent upgrades and future experimental plans at the facilities.
Read the full abstract

All authors W.S. Porter, D.W. Bardayan, M. Brodeur, C. Dembski, P.D. O'Malley, F. Rivero, W.W. von Seeger, C. Boomershine, O. Bruce, S.R. Carmichael, S. Coil, A.M. Houff, J.J. Kolata, D. Schroeder, A.A. Valverde, R. Zite

Nuclear Experiment

$^{16}$O(p,$\gamma$)$^{17}$F Reaction and the C and O Isotopic Ratios in Red Giant Branch Stars

D. Robb, P. McGlynn, M. Aliotta et al. (+55 more)

The $^{16}$O/$^{17}$O isotopic ratio is a widely used tracer of nucleosynthesis and mixing processes in red giant stars. Its value depends on the rates of the proton-capture reactions responsible for the production and destruction of $^{16}$O and $^{17}$O among which the $^{16}$O(p,$\gamma$)$^{17}$F reaction plays a central role, as it involves both isotopes. This work reports on a new measurement of the $^{16}$O(p,$\gamma$)$^{17}$F cross section carried out at the Laboratory for Underground Nuclear Astrophysics (LUNA) over a center-of-mass energy range of 200 - 380 keV, a region previously unexplored by experimental studies. Two complementary techniques were employed: prompt gamma-ray detection and activation. The results obtained with the two techniques are consistent within experimental uncertainties. From the measured cross sections and existing literature data, we evaluate a new thermonuclear reaction rate, which is then used to demonstrate how simultaneous measurements of stellar carbon and oxygen isotopic ratios constrain the initial mass and the extent of the mixing events in red giant branch stars. In particular, we demonstrate how the $^{12}$C/$^{13}$C abundance ratio is primarily sensitive to the temperature T$_{\textrm{max}}$ attained during mixing, whereas the $^{16}$O/$^{17}$O abundance ratio is highly sensitive to the initial stellar mass M$_i$. Therefore, simultaneous measurements of these isotopic ratios can disentangle and place stringent constraints on M$_i$ and T$_{\textrm{max}}$, and the remaining uncertainty is now dominated by stellar abundance measurements rather than nuclear-physics inputs.
Read the full abstract

All authors D. Robb, P. McGlynn, M. Aliotta, C. Ananna, F. Barile, L. Barbieri, D. Bemmerer, A. Best, R. Biasissi, A. Boeltzig, R. Bonnell, C. Broggini, C.G. Bruno, A. Caciolli, M. Campostrini, F. Casaburo, F. Cavanna, G.F. Ciani, T. Chillery, P. Colombetti, A. Compagnucci, P. Corvisiero, L. Csedreki, T. Davinson, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, A. Formicola, Zs. Fülöp, G. Gervino, R. M. Gesuè, G. Gosta, Gy. Gyürky, A. Guglielmetti, C. Gustavino, C. Hebborn, G. Imbriani, M. Junker, M. Lugaro, J. Marsh, E. Masha, R. Menegazzo, D. Mercogliano, V. Paticchio, D. Piatti, P. Prati, D. Rapagnani, V. Rigato, M. Rossi, R. Sariyal, R.S. Sidhu, J. Skowronski, O. Straniero, T. Szücs, S. Turkat, M. Vagnoni, S. Zavatarelli

Nuclear Experiment · Cross-listed from nucl-th

Constraining three-nucleon forces in nuclear lattice effective field theory

Serdar Elhatisari, Ulf-G. Meißner, Zhengxue Ren et al. (+1 more)

We study short-range three-nucleon forces (3NFs) in nuclear lattice effective field theory with a chiral two-nucleon interaction at N${}^3$LO. The one-pion-exchange ($c_D$) and contact ($c_E$) terms of the leading 3NF are decomposed into locally and non-locally smeared components and supplemented by partial-wave-resolved pair contacts coupled to the density of a third nucleon. We determine their coefficients from nuclear binding energies for nuclei in the mass range from $A=3$ to $A=40$ and neutron–alpha finite-volume energies. This allows to work out the minimal three-nucleon force that can be used for future precision studies in NLEFT.
Read the full abstract

All authors Serdar Elhatisari, Ulf-G. Meißner, Zhengxue Ren, Shuang Zhang

Nuclear Experiment

Probing the production mechanisms of virtual photons at RHIC

STAR Collaboration

We report the measurement of direct virtual photon ($\gamma^*_\text{dir} \rightarrow e^+e^-$) in four Au+Au collision energies at $\sqrt{s_\text{NN}}$ = 14.6–54.4 GeV. The $\gamma^*_\text{dir}$ yields scale with charged-particle multiplicity ($(dN_{\mathrm{ch}}/d\eta)^{\alpha}$) as $\alpha=1.43 \pm 0.04 \text{(stat.)} \pm 0.03\text{(sys.)}$, independent of collision energies and centralities, exceeding hadronic expectations and indicating notable contribution from QGP phase. At $\sqrt{s_{\rm NN}}=$ 54.4 GeV, the direct virtual photon mass distributions are further studied over $0.1 < M_{ee} < 1.1$ GeV/$c^2$, and are found to evolve from exponential to power-law form with increasing $p_\text{T}$, signaling a shift from "blackbody" radiation to emission governed by Kroll-Wada formalism.
Read the full abstract

Nuclear Experiment · Cross-listed from nucl-th

Collective-flow signatures of bubble nuclei in intermediate-energy projectile fragmentation reactions

Ge Ren, Chun-Wang Ma, Xi-Guang Cao et al. (+2 more)

Characterized by central density depletion, bubble nuclei represent an important class of exotic nuclear structures. Collective flow in the $^{40}$Ca+$^{9}$Be projectile fragmentation reaction at 140 MeV/u is investigated using the extended quantum molecular dynamics (EQMD) model with a parameter on of the isoscalar monopole excitation strength $\varepsilon$. The projectile $^{40}Ca$ is initialized as a relaxed ten-$\alpha$ cluster configuration exhibiting a bubble-like density distribution. The results reveal that increasing $\varepsilon$ modifies the density distribution and the size of the depleted central region of bubble, producing pronounced changes in fragment yields and collective flow around $\varepsilon\approx0.5$. Below this value, heavy-fragment production plays a significant role, while the directed flow $v_1$ of protons and neutrons remains predominantly negative, indicating preferential emission toward the target side. Above $\varepsilon\approx0.5$, enhanced expansion of the central low-density region suppresses heavy residues and drives $v_1$ toward positive values. In contrast, preformed $\alpha$ clusters show different responses, reflecting their origin in the initial cluster configuration rather than solely in secondary decay. At low excitation, the cluster flow exhibits a pronounced impact-parameter dependence, whereas stronger excitation weakens cluster binding and suppresses directional anisotropy, driving the flow close to zero. The rapidity slopes of the flow coefficients also vary systematically with $\varepsilon$, tracing changes in emission anisotropy during expansion. These findings extend traditional static descriptions by probing the dynamical evolution of exotic structures in heavy-ion reactions and the contrasting collective-flow behavior of preformed clusters and single nucleons constitutes a sensitive dynamical probe of bubble-like structures.
Read the full abstract

All authors Ge Ren, Chun-Wang Ma, Xi-Guang Cao, Kai-Xuan Cheng, Jie Pu

Nuclear Experiment · Cross-listed from nucl-th

Strange-quark-number-dependent response to partonic dynamics in baryon-rich Au+Au collisions

Di Zhao, Xun Zhu and Gao-Chan Yong

We identify a strange-quark-number-dependent hierarchy in the response to explicit partonic dynamics by comparing PHSD5.2 with its hadron–string limit in baryon-rich Au+Au collisions at $\snn=3.0$–$7.2$~GeV. Crossing the local conversion threshold alone does not ensure a visible final-state signal: abundant-hadron flow changes little at 3–4.5~GeV, whereas the fractional yield response becomes ordered at 6.2–7.2~GeV, reaching $S_{|s|=1}\simeq0.2$–$0.3$, $S_{|s|=2}\simeq0.65$, and $S_{|s|=3}\simeq0.93$ at 7.2~GeV. The hierarchy is consistent with an enlarged recombination phase space for strange constituents released from different pre-hadronic sources, but does not by itself establish an increase in the total $s+\bar s$ abundance or stronger strange-quark clustering. Since $S_X$ is a model-defined response rather than a direct observable, matched excitation functions of $\Xi^-/\Lambda$ and $\Omega^-/\Lambda$, together with high-$m_T$ proton elliptic flow, provide experimentally accessible discriminants between the predicted PHSD and HSD dynamics.
Read the full abstract

Tuesday 13 October · still arriving

Nuclear Experiment

The 3He({\alpha},{\gamma})7Be {\gamma}-ray angular distribution: measured, and calculated by effective field theory

S. Turkat, P. Hempel, X. Zhang et al. (+26 more)

The 3He(alpha,gamma)7Be reaction takes place in several distinct astrophysical scenarios. First, in solar hydrogen burning, 3He(alpha,gamma)7Be controls the competition between the pp-I chain, on the one hand, and the pp-II and -III chains, on the other hand. Its rate directly affects the solar model predictions for the well-measured 7Be and 8B solar neutrino fluxes, which can in principle be used as solar thermometer. Second, in Big Bang nucleosynthesis, 3He(alpha,gamma)7Be is the main production channel for primordial 7Li, the decay product of 7Be. Finally, the reaction is believed to produce radioactive 7Be in astrophysical novae. The cross section of this reaction has been studied previously using different methods, namely 7Be activation, 7Be recoil detection, and in-beam {\gamma}-ray detection. The latter studies have in many cases been performed with just one detector in close geometry. Here, for the first time a comprehensive measurement of the 3He({\alpha},{\gamma})7Be {\gamma}-ray angular distribution is reported. Altogether 22 high-purity germanium detectors were used, arranged at 27-145 degrees angle with respect to the beam direction. Data were taken at 442-1213 keV center-of-mass energy. In addition, one data point for the astrophysical S-factor was obtained with the activation method. The angular data are compared with the predictions from a hybrid theoretical approach, where the E1 transitions are modeled using a cluster-based effective field theory (EFT) while the M1 and E2 transitions within an EFT-inspired framework. Good agreement is found, if the interference among these multipolarities is taken into account in the theory.
Read the full abstract

All authors S. Turkat, P. Hempel, X. Zhang, S. Akhmadaliev, D. Bemmerer, A. Boeltzig, A. Caciolli, A. Freimann, M. Grieger, S. Hammer, T. Hensel, L. Hübinger, N. A. Hofmann, J. Koch, T. Lossin, F. Ludwig, E. Masha, K. M. Nollett, M. Osswald, S. Reinicke, S. Rümmler, K. Schmidt, K. Stöckel, T. Szücs, S. Vincent, L. Wagner, J. Wünsche, A. Yadav, K. Zuber

Monday 12 October

Nuclear Experiment · Cross-listed from hep-ph

Parton and nuclear dynamics at large $x$: the CJ26 global QCD analysis

Alberto Accardi, Matteo Cerutti, Cynthia E. Keppel et al. (+4 more)

We present the new CTEQ-JLab global QCD analysis, called CJ26, that simultaneously fits parton distribution functions of the proton and nuclear effects in deuteron targets. This work includes, for the first time in a global fit, the full set of JLab 6 GeV inclusive DIS measurements and the first published JLab 12 GeV data. The analysis focuses on the large-$x$ region, and carefully treats the interplay between higher-twist effects and off-shell corrections in low-energy proton and deuteron target data. We discuss their effect on quark and gluon distributions, and highlight the importance of quantifying the experimental correlated systematic uncertainty to achieve fits of the highest accuracy. We also outline how upcoming data may help unravel the nuclear and partonic dynamics in light nuclei. The extracted next-to-leading order parton distributions are available on the CJ web pages in LHAPDF format for general use, accompanied by leading- and higher-twist structure functions calculated with the simultaneously fitted PDFs, higher-twist corrections, and off-shell corrections. This write up clarifies several points that became clearer while finalizing the CJ26 paper and can be read as a companion to the latter.
Read the full abstract

All authors Alberto Accardi, Matteo Cerutti, Cynthia E. Keppel, Shujie Li, J. F. Owens, Sanghwa Park, Peter Risse

Nuclear Experiment · Cross-listed from physics.ins-det

FINESSE: A Versatile Beamline for Fundamental Interactions with Neutrons at the European Spallation SourcE

J. Amaral, J. Barrow, M. Bartis et al. (+71 more)

FINESSE (A Versatile Beamline for Fundamental Interactions with Neutrons at the European Spallation SourcE) is a proposed versatile beamline for fundamental interactions with neutrons at the European Spallation Source. Building on the HIBEAM design studies, FINESSE extends the original concept into a dual-guide beamline capable of operating either in a high-flux configuration or in a low-background configuration within a single ESS beam port. The high-flux branch is optimized for rare-process searches, including neutron–antineutron oscillations, neutron–sterile-neutron transitions, axion-like-particle searches, neutron charge measurements, and rare neutron decays. The low-background branch is designed for precision measurements requiring strong suppression of prompt and line-of-sight backgrounds, with a cryogenic neutron electric-dipole-moment experiment used as a benchmark case. A baseline exchangeable-guide concept has been developed in which only short guide sections inside the ESS bunker are exchanged, while the upstream extraction system and chopper positions remain fixed. A staged implementation, Short FINESSE, would use the upstream section of the high-flux beamline together with a compact magnetically controlled experimental region, enabling an early physics and R&D programme before completion of the full facility. This paper summarizes the scientific case, beamline concept, guide simulations, chopper and timing system, magnetic-field control, detector developments, and staged implementation strategy. FINESSE would establish a long-term particle-physics infrastructure at ESS, providing a beamline for both discovery-driven searches and precision neutron measurements throughout the lifetime of the facility.
Read the full abstract

All authors J. Amaral, J. Barrow, M. Bartis, D. H. Beck, P. M. Bentley, J. Bijnens, G. Brooijmans, L. J. Broussard, A. Burgman, G. Cibinetto, G. Croci, D. D. Di Julio, P. Fierlinger, B. W. Filippone, C. Gatto, H. Gisbert, H. Gogoi, G. Gorini, A. Gutierrez-Rodriguez, A. Koberinski, M. Kaczmarek, M. Silarski, M. O'Riordan, A. Heinz, J. Henderson, M. Holl, H. T. Johansson, B. Jonsson, H. Henriksson, L. Jonsson, Y. Kamyshkov, M. P. Kuhl, P. Kinhult, R. Kolevatov, A. Kozela, W. T. Lee, K. K. H. Leung, T.-J. Liang, G. Luzin, B. Meirose, D. Milstead, R. Mohapatra, G. Muhrer, A. Muraro, A. Nepomuceno, N. Okada, A. Oskarsson, T. Palasz, R. Pasechnik, V. Larsson, L. B. Persson, O. Putignano, J. Ramsey, C. Snow, L. Werselius, B. Rataj, A. Rodriguez-Sanchez, A. Saunders, V. Santoro, F. Scioscioli, R. Shrock, D. Silvermyr, H. Sina, W. M. Snow, Y. V. Stadnik, L. Tchelidze, N. Tsapatsaris, A. Tureanu, A. Vilela Pereira, M. Wolke, J. Womersley, S. Xu, A. R. Young, K. Osterberg

Nuclear Experiment · Cross-listed from hep-ph

Lepton Flavour Universality in Semileptonic $\bar B_{(s)} \to D_{(s)}^{(\ast)}$ Transitions

Yu-Chen Hu, Cong-Cong Ye, Craig D. Roberts et al. (+1 more)

Using continuum Schwinger function methods, we deliver parameter-free pointwise predictions for the complete set of twelve Standard Model (SM) $\bar B_{(s)} \to D_{(s)}^{(\ast)}$, i.e., $b\to c$, semileptonic transition form factors on the entire kinematically accessible domain. Therewith, we calculate SM theory values for the decay-rate ratios of $\tau$ and $\mu$ final states: $\{ R(D) \, , \, R(D)^\ast \} = \{ 0.290(11) \, , \, 0.267(5) \}$, $\{ R(D_{s}) \, , \, R(D_{s}^{\ast}) \} = \{ 0.283(11) \, , \, 0.251(5) \}$. The former is consistent with an existing average of SM estimates, but disagrees with the experimental average by $2.8\sigma$. Comparing transitions with light quark and strange quark spectators, we find a $2.3\sigma$ signal for violation of SU$(3)$ flavour symmetry, expressed at the 5% level in $D_{(s)}^\ast$ final states. It is induced by Higgs boson couplings into the strong interaction and modulated by phenomena deriving from emergent features of the strong interaction.
Read the full abstract

All authors Yu-Chen Hu, Cong-Cong Ye, Craig D. Roberts, Zhao-Qian Yao

Nuclear Experiment · Cross-listed from hep-ph

Conserved-charge diffusion in hot and dense QCD matter

Dushmanta Sahu, Kangkan Goswami and Raghunath Sahoo

We study the coupled diffusion of baryon number, electric charge, and strangeness in hot and dense quark matter using a three-flavor Nambu-Jona-Lasinio model with self-consistently generated constituent quark masses. The complete diffusion matrix is evaluated within a relaxation-time kinetic approach, including its diagonal and off-diagonal components. We find that the off-diagonal transport coefficients exhibit distinct temperature and baryon-chemical-potential dependence associated with the flavor-dependent composition of the charge carriers. We further investigate generalized charge diffusivities and mobilities obtained from the corresponding susceptibilities. At finite baryon chemical potential, the baryon and strangeness mobility scales cross, reflecting the different density dependence of their transport coefficients and susceptibilities. The results provide model benchmarks for coupled conserved-charge transport in baryon-rich QCD matter.
Read the full abstract

Nuclear Experiment

Letter of Intent for Alpha Knockout from Nuclei in Hard Exclusive Processes with ALERT

Whitney R. Armstrong{\dag}, Ian Cloët, Fernando A. Flor et al. (+21 more)

We propose to measure hard exclusive $\alpha$-knockout reactions from the light $\alpha$-conjugate nuclei $^{12}$C, $^{16}$O, and $^{20}$Ne using electron scattering. Three reaction channels will be measured for the first time on the same target set: (i) the quasi-elastic knockout $(e, e' \alpha)$ knockout, which establishes a baseline against $\alpha$-clustering model calculations and tests final-state-interaction (FSI) models; (ii) coherent deeply virtual Compton scattering (DVCS) on a bound $\alpha$, which provides a quark-level probe of the bound system through the beam-spin asymmetry; and (iii) coherent vector-meson production ($\phi$ and J/{$\psi$}) on a bound $\alpha$, which probes the gluon distribution of the bound cluster through two-gluon exchange. The central observables are ratios of cross sections and beam-spin asymmetries between the bound $\alpha$ in $^{12}$C, $^{16}$O, and $^{20}$ Ne and the free $^4$He ground state. Together these measurements directly address the question of the role of QCD in the structure of light nuclei : do the quark and gluon distributions of an $\alpha$ embedded in a heavier nucleus differ from those of a free 4He, and do those modifications track the increasing $\alpha$-clustering strength along the $\alpha$-conjugate chain? The measurement will use the 12 GeV CEBAF accelerator in Hall B with the CLAS12 spectrometer instrumented with the ALERT low-energy recoil detector and high-pressure gas straw targets. ALERT, which replaced the CLAS12 silicon vertex tracker, was successfully commissioned and operated during Run Group L (RG-L) from April through August 2025. It uniquely provides identification of low-momentum recoiling light ions (p, d, t, $^3$He, and $^4$He) close to the beamline at the high luminosities required by these exclusive channels.
Read the full abstract

All authors Whitney R. Armstrong{\dag}, Ian Cloët, Fernando A. Flor, Sylvester Joosten Bobae Kim, Minho Kim, Henry T. Klest, Zein-Eddine Meziani, Chao Peng, Valerii Klimenko, Noémie Pilleux, Maria Żurek, Jacob C. Dulya, Zhiwan Xu, Lamiaa El Fassi, Penn Smith, Nazmus S. Ifat, Sangbaek Lee, Suman Shrestha, Nikos Sparveris, Fatiha Benmokhtar, Christine Ploen, Raphaël Dupré, Jennifer Rittenhouse West, Stanley J. Brodsky

Sunday 11 October

Nuclear Experiment · Cross-listed from nucl-th

Higher-order corrections to beta decays and nuclear structure

Grigor Sargsyan and Ayala Glick-Magid

Precision measurements of nuclear $\beta$ decay offer a powerful route to tests of physics beyond the Standard Model, but interpreting measurements spectra and correlation observables requires control of subtle nuclear-structure effects. This chapter develops a framework for calculating higher-order corrections–small contributions that can become important at the precision sought in searches for new interactions. After motivating their role in $\beta$-decay observables (with radiative corrections treated in the accompanying chapter), we introduce the relevant kinematics and multipole expansion of the shape factor, identify the subleading contributions, and present the impulse-approximation multipole operators. We then describe the nuclear many-body methods used to obtain the required states and transition densities, and derive the corresponding operator matrix elements in the harmonic-oscillator basis. Taken together, these ingredients enable systematic calculations of nuclear shape factors beyond the long-wavelength approximation, including higher-order multipoles where needed. By helping distinguish Standard-Model recoil effects from possible signatures of new physics, this framework supports the interpretation of increasingly precise $\beta$-decay experiments.
Read the full abstract

Saturday 10 October

Nuclear Experiment · Cross-listed from physics.ins-det

Response of GAGG(Ce) scintillators to different charged particles

Kai-Jie Zhou, Zai-Hong Yang, Hooi-Jin Ong et al. (+13 more)

Charged-particle telescopes play an essential role in studies of nuclear clustering, which require high-resolution detection of charged breakup fragments. GAGG(Ce) is a promising scintillator for charged-particle detection at high counting rates because of its high light yield, fast response, and non-hygroscopic nature. However, systematic data on its light-output response to different charged particles remain scarce. In this work, we present a systematic study of the scintillation light-output response of GAGG(Ce) crystals to various charged particles and quantify the associated quenching behavior. The relationship between the scintillation light output and the deposited energy is established over a broad range of particle species and energies, providing essential experimental input for response modeling and energy calibration of GAGG(Ce)-based charged-particle detector systems.
Read the full abstract

All authors Kai-Jie Zhou, Zai-Hong Yang, Hooi-Jin Ong, Qi-Te Li, Ze-Yu Du, Jia-Wei Bian, Cheng Wang, Jin-Ning Li, Satoru Terashima, Bing-Feng Lv, Xuan Wang, Zhi-Chao Zhang, Hong-Na Liu, Yu-Yang Yu, Peng-Jie Li, Ye-Lei Sun

Friday 9 October

Nuclear Experiment · Cross-listed from nucl-th

Deconfinement and the Charge Susceptibility Matrix of QCD

Christopher Grace, Brady Mowbray and Christopher Plumberg

At sufficiently high temperatures, lattice Quantum Chromodynamics (QCD) calculations predict that nuclear matter undergoes a rapid crossover to a novel, deconfined state known as the quark-gluon plasma (QGP), in which quark flavors essentially behave like independent particles. Here we explore the nature of this transition by introducing two new thermodynamic observables which we refer to as the diagonality and the rescaled curvature of the QCD equation of state (EoS). By comparing these observables in the case of lattice QCD calculations with those of simple toy models and more sophisticated hadronic resonance models, we show that both the diagonality and the rescaled curvature provide complementary insights into the degree of independence between different quark flavors and the underlying degrees of freedom in the system as functions of temperature. We propose that these observables may help to clarify the nature of the transition region and the onset of deconfinement in nuclear matter.
Read the full abstract

Nuclear Experiment · Cross-listed from nucl-th

Competitive constraints on exotic tensor currents from $EC/\beta^+$ ratios

Victor Dumenil and Leendert Hayen

We introduce the ratio of electron capture to positron decay rates of unstable nuclei as a probe for exotic tensor currents in the electroweak sector. We calculate nuclear structure corrections and newly derived radiative corrections and obtain competitive limits on exotic tensor couplings using historically available data to find $\varepsilon_T = (1.06 \pm 0.76)\times 10^{-3}$ which is competitive with collider searches and the global $\beta$-decay database. In doing so, we resolve a 50-year-old tension in the strongly hindered $^{22}$Na transition by retaining higher-order operators, obtaining a consistent description of its different weak-decay observables. Finally, we discuss the potential of this method to significantly improve tensor constraints using modern cryogenic quantum sensors.
Read the full abstract

Nuclear Experiment · Cross-listed from nucl-th

Impact of ab initio E1 strength on neutron capture rates along the nickel isotopic chain

Francesca Bonaiti and Joanna E. Sobczyk

Nucleosynthesis simulations of the r-process require neutron capture rates for neutron-rich nuclei, many of which lie beyond experimental reach. Predicting these rates relies on theoretical calculations of the low-energy electric dipole (E1) strength near the neutron threshold. We present the first ab initio computation of the E1 strength along the nickel isotopic chain, for $^{58}$Ni and the even-even isotopes $^{68-80}$Ni. The E1 strength is obtained with the Lorentz integral transform coupled-cluster (LIT-CC) method, extended to axially symmetric reference states to reach open-shell nuclei, using two- and three-nucleon interactions from chiral effective field theory. The approach is benchmarked against the measured photoabsorption cross section of $^{58}$Ni and the E1 strength of $^{68}$Ni. Along the chain we find low-lying E1 strength above the neutron threshold that grows with neutron number. Including it in the reaction code TALYS enhances the neutron capture rates forming $^{68-78}$Ni between 3 and 10 GK, with an effect that increases with temperature and neutron number and an uncertainty dominated by the inversion of the integral transform. For $^{80}$Ni, where strong pygmy dipole strength lies just above threshold, the enhancement sets in already around 0.5 GK. Together, these results open the way to ab initio input for neutron capture rates along isotopic chains far from stability.
Read the full abstract

Nuclear Experiment · Cross-listed from nucl-th

Final-state centrality in relativistic heavy-ion simulations from neural networks

Anibal Bezerra and Fernando G. Gardim

Experiments in relativistic heavy-ion collisions determine centrality from final-state quantities, usually the charged-particle multiplicity. Performing the same in hydrodynamic simulations requires millions of events, which is impractical for state-of-the-art hybrid models, and centrality is therefore commonly approximated by the initial entropy or energy. We show that neural networks trained on a few hundred hybrid events predict the event-by-event multiplicity and mean transverse momentum $[p_T]$ with relative errors of 1–2%, which makes it possible to generate millions of collisions at a small fraction of the cost of the full simulation. For Pb–Pb collisions at $2.76$~TeV and Au–Au collisions at $200$~GeV, the initial-state and final-state definitions select nearly the same events in 10%-wide classes, but up to 20% of the events change class when the classes are 1% wide. We then compute the fluctuations of $[p_T]$ and its Pearson correlations with a proxy of the elliptic flow, estimated from the initial eccentricity, and with multiplicity. The first correlation is insensitive to how centrality is defined, while the second changes substantially. The approach can be applied at every design point of Bayesian analyses at modest additional cost.
Read the full abstract

Nuclear Experiment · Cross-listed from hep-ph

nCTEQ26 nuclear parton distribution functions

nCTEQ Collaboration, K. Greve, T. Ježo et al. (+10 more)

We present the new release of nuclear parton distribution functions (nPDFs) from the nCTEQ collaboration: nCTEQ26. In this global analysis, we combine our recent, more selective studies of different experimental measurements and extend them to determine a modern set of nPDFs based on the largest selection of data considered to date. This selection includes neutral- and charged-current deep-inelastic scattering (DIS), fixed-target Drell-Yan, and a large variety of collider data from RHIC and LHC Runs I and II. On the theoretical side, we match this considerably extended kinematic range with a new nPDF parametrization that combines a flexible functional form of the x-dependence with a quadratic logarithmic nuclear A-dependence as well as target-mass and deuteron corrections for the reliable inclusion of high-x DIS data. Following our previous successful work, we partially employ a data-driven approach that allows us to not only include open heavy-quark data, but also quarkonium data. In addition, we establish the consistency of this approach by comparing it to an alternative fit based on perturbative predictions of open heavy-quark data alone. We determine the uncertainties of our nCTEQ26 nPDFs with a Hessian error analysis, test their reliability by comparing our nPDFs to other, similar recent analyses, and make predictions for current and future experimental measurements that have not been included in the analysis.
Read the full abstract

All authors nCTEQ Collaboration, K. Greve, T. Ježo, A. Kusina, J. Wissmann, M. Klasen, K. Kovařík, C. Léger, J.G. Morfín, F.I. Olness, P. Risse, I. Schienbein, J.Y. Yu

Nuclear Experiment

Probing high-momentum components in $^{16}$O via zero-degree $(p,d)$ cross-section ratios

Super-FRS Experiment Collaboration: X. Wang, H. J. Ong, S. Terashima et al. (+39 more)

The $^{16}$O$(p,d)^{15}$O reaction was measured at zero degrees for incident-proton energies of 403, 604, 907 and 1209 MeV. Cross-section ratios for the 6.18-MeV (3/2$^-$) and 5.24-MeV (5/2$^+$) excited-state transitions, normalized to the ground-state transition, were previously reported in Wang et al., Phys. Lett. B 879, 140563 (2026), doi:10.1016/j.physletb.2026.140563, together with their implications for high-momentum neutron components in $^{16}$O. The present work extends that study by providing additional experimental and data-analysis details, and by reporting for the first time the ratio $R_{7.3}$, defined as the cross section populating the 7.28-MeV (7/2$^+$) state relative to that for the ground state. The positive-parity state ratios exhibit a pronounced momentum dependence, consistent with representative variational Monte Carlo trends.
Read the full abstract

All authors Super-FRS Experiment Collaboration: X. Wang, H. J. Ong, S. Terashima, I. Tanihata, Y. K. Tanaka, H. Geissel, N. Aoi, Y. Ayyad, J. Benlliure, F. Farinon, H. Fujioka, J. Gellanki, C. L. Guo, E. Haettner, W. L. Hai, M. N. Harakeh, C. Hornung, K. Itahashi, R. Janik, N. Kalantar-Nayestanaki, R. Knöbel, N. Kurz, K. Miki, I. Mukha, T. Myo, T. Nishi, D. Y. Pang, S. Pietri, A. Prochazka, C. Rappold, M. P. Reiter, J. L. Rodríguez-Sánchez, C. Scheidenberger, H. Simon, B. Sitar, P. Strmen, B. H. Sun, K. Suzuki, H. Weick, J. S. Winfield, X. D. Xu, J. W. Zhao

Nuclear Experiment · Cross-listed from nucl-th

Octupole correlations in the excited $0^+$ states and two-neutron transfers in actinide nuclei

Kosuke Nomura

Impacts of octupole correlations on low-energy excited $0^+$ states and two-neutron transfer intensities in Ra and Th isotopes are analyzed within the interacting boson model, using the Hamiltonian parameters that are obtained from microscopic nuclear density functional theory calculations. Incorporating the octupole degree of freedom in the model is shown to give an overall reasonable description of the ground-state-band energy levels and to lower the $0^+_2$ ones significantly. The calculation yields a number of excited $0^+$ states, most of which are formed by the configurations of more than one octupole boson. Octupole correlations make significant contributions to the $0^+_1 \to 0^+_2$ $(p,t)$ and $(t,p)$ transfer intensities in those nuclei in which the octupole collectivity is most enhanced. Behaviors of the predicted transfer intensities with the increasing neutron number along the isotopic chain reflect nuclear structural evolution.
Read the full abstract

Nuclear Experiment · Cross-listed from hep-ph

Dijet hadrochemistry: tomography of jet-induced medium excitation and diffusion wake

Cong Yi, Xiang-Yu Wu, Zhong Yang et al. (+4 more)

Energetic partons traversing the quark-gluon plasma in relativistic heavy-ion collisions induce a medium response that modifies the production of associated hadrons, whose chemical composition provides a sensitive probe of this response. We study jet-associated hadrochemistry using the coupled linear Boltzmann transport and hydrodynamics model with a hybrid hadronization scheme that combines Cooper–Frye particlization, quark coalescence and string fragmentation. For inclusive charged jets in $p+p$ and 0–10% central Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV, the calculated in-cone $K/\pi$ and $p/\pi$ ratios are enhanced in Pb+Pb relative to $p+p$ collisions, consistent with preliminary ALICE measurements, with coalescence between shower and thermal partons providing a substantial contribution. Extending the analysis to dijet events, we predict that both ratios are enhanced around the leading and subleading jets, more strongly around the subleading jet and more pronounced for larger radial size. After mixed-event acceptance correction and sideband background subtraction, the yields of associated pions, kaons and protons all become negative near $|\Delta\phi|\simeq\pi/2$, signaling a depletion caused by the diffusion wake. The $K/\pi$ and $p/\pi$ ratios of these deficits remain finite and exceed the $p+p$ values around the jet peaks, indicating that the missing hadrons originate from jet-excited medium. These results establish dijet hadrochemistry as an experimentally accessible tomographic probe of jet-induced medium excitation and the diffusion wake.
Read the full abstract

All authors Cong Yi, Xiang-Yu Wu, Zhong Yang, Pi Duan, Guang-You Qin, Xin-Nian Wang, Wenbin Zhao

Nuclear Experiment · Cross-listed from physics.ins-det

Application and Optimization of the GET Electronics System for Double-Sided Silicon Strip Detector Readout

Jiawei Bian, Zaihong Yang, Qite Li et al. (+7 more)

Double-sided silicon strip detectors (DSSDs) are widely used for charged-particle detection in nuclear reaction experiments. However, the large number of readout channels associated with DSSDs places stringent demands on front-end electronics and data acquisition systems, particularly in experiments employing large detector arrays. In this work, we investigate the application and optimization of the Generic Electronics for Time Projection Chambers (GET) system for multi-channel DSSD readout. Through optimization of the DC-blocking capacitors on the custom-designed interface board and waveform-based energy extraction algorithms, the readout system achieves an energy resolution of {\sigma} = 22 keV for 5.49 MeV alpha particles. Its performance is further validated in a representative nuclear physics experiment employing charged-particle telescopes. The results demonstrate that the GET system provides a versatile and scalable waveform-sampling solution for multi-channel DSSD readout.
Read the full abstract

All authors Jiawei Bian, Zaihong Yang, Qite Li, Zeyu Du, Xuan Wang, Ningtao Zhang, Pengjie Li, Zhongtao Shen, Kaijie Zhou, Cheng Wang

Thursday 8 October

Nuclear Experiment · Cross-listed from hep-ph

Bosonic Contribution to Parity-Violating Møller Scattering at NNLO

Lisong Chen, Jens Erler, Ayres Freitas et al. (+1 more)

We calculate the dominant bosonic two-loop virtual electroweak corrections to parity-violating Møller scattering at low energies. The electron effective weak charge is extracted from the polarization asymmetry, retaining all contributions that are enhanced by $(1-4\sin^2\theta_W)^{-1}$ or $\ln^2(M_{W,Z}^2/Q^2)$ relative to the tree-level contribution. Analytical results are obtained using the expansion by regions method in the low-energy limit $Q^2\ll M_{W,Z}^2$. Within this approximation, the dominant two-loop bosonic corrections shift the electron effective weak charge (or equivalently the polarization asymmetry) by $0.3\%$. We examine the origin of the leading contributions to this result and assess the remaining theoretical uncertainty from purely bosonic contributions for the MOLLER experiment to about 0.1%.
Read the full abstract

All authors Lisong Chen, Jens Erler, Ayres Freitas, Juhun Kwak

Wednesday 7 October

Nuclear Experiment

Double-differential neutron-induced cross sections on Fe-nat at GANIL-NFS

L. de Arruda, D. Tarrío, X. Ledoux et al. (+8 more)

An experimental campaign to measure double-differential cross sections (DDXS) for light-charged particles (LCPs) emitted from $^{\rm nat}$Fe was carried out in 2023 at the Neutrons For Science (NFS) facility of GANIL, France. The Medley experimental setup, specifically designed for light-ion measurements, was used for this campaign. The setup was installed in the white neutron beam line and irradiated with neutrons of energies up to 44 MeV. The Time-of-Flight (TOF) technique was used to obtain $^{\rm nat}$Fe(n,pX) double-differential cross sections for all neutron energies within the white-neutron beam's energy range. This work highlights important steps in the data-analysis procedure and reports the first results from this experimental campaign.
Read the full abstract

All authors L. de Arruda, D. Tarrío, X. Ledoux, S. Pomp, D. Ramos, I. Ipatova, P. Kanth, I. Kodeli, M. Lantz, E. Pirovano, U. Tippawan

Nuclear Experiment · Cross-listed from physics.ins-det

Timing Challenges in Transmission Silicon Detectors for Light Ions

Diego Tarrio, Friedrich Karl Moraht, Lucas de Arruda et al. (+3 more)

Transmission silicon detectors are widely used in $\Delta E$–$E$ telescope configurations for particle identification and timing in nuclear physics experiments. Variations in signal rise time can introduce time-walk effects that degrade time-of-flight measurements, as recently observed in light-ion production experiments at the Neutrons For Science (NFS) facility at GANIL using the Medley setup. This work investigates the influence of particle energy and detector non-uniformity on signal rise time.
Read the full abstract

All authors Diego Tarrio, Friedrich Karl Moraht, Lucas de Arruda, Stephan Pomp, Xavier Ledoux, Diego Ramos

Nuclear Experiment · Cross-listed from hep-ph

Tensor-structure sum rules for spin-1 targets at all $Q^2$

Vladimir Pascalutsa and Marc Vanderhaeghen

We derive a family of sum rules for the tensor structure functions of targets with spin one or higher, rooted in exact Siegert relations. The mixed rank-two $TT$–$LT$ degeneracy combines amplitudes of opposite crossing parity and, under the superconvergence assumption, gives $\int_0^1\! d x\,[b_2(x,Q^2)-3b_4(x,Q^2)]=0$ in the Hoodbhoy–Jaffe–Manohar (HJM) basis. At large $Q^2$, the protected moment agrees with Detmold's target-mass-complete twist-two OPE; in the strict Bjorken projection, and if $b_4$ is neglected, it reduces to the Efremov–Teryaev (ET)-type condition $\int_0^1\! d x\,x\,b_1(x)=0$, whose measured-range footprint is consistent with the HERMES data. Two further rank-two combinations connect crossing-even amplitudes and determine the corresponding subtraction functions through weighted HJM moments. The protected combination can be isolated through separated tensor $LT$ and $TT$ responses, providing a direct experimental strategy for JLab and, ultimately, a future EIC.
Read the full abstract

Nuclear Experiment · Cross-listed from nucl-th

Novel chiral-wobbling excitation mode in atomic nuclei

Kouser Qureshie, S. P. Rouoof, J. A. Sheikh et al. (+9 more)

The properties of high-spin band structures in $^{74}$Br nucleus are investigated using the triaxial projected shell model (TPSM) and particle triaxial rotor (PTR) approaches. It has already been demonstrated that lowest three bands observed in $^{74}$Br have a characteristic feature of a chiral-wobbler. The first excited band is the chiral partner of the yrast band and the second excited band is the wobbling band based on the yrast state. We have analyzed the third excited band using the TPSM and PTR calculated quantities, and a unique character of this band is revealed. It is predicted that this band is the chiral partner of the second excited band, and is also a wobbling mode based on the first excited band.
Read the full abstract

All authors Kouser Qureshie, S. P. Rouoof, J. A. Sheikh, Nazira Nazir, G. H. Bhat, S. Jehangir, N. A. Rather, R. J. Guo, S. Y. Wang, C. Liu, Q. B. Chen, S. Frauendorf

Nuclear Experiment

Event-by-event net-charge fluctuations in pp, OO, Ne-Ne, and Pb-Pb collisions with ALICE at the LHC

Nida Malik

Investigations involving the event-by-event fluctuations of conserved quantities, like net charge, net baryon number, and strangeness in heavy-ion collisions, provide insights into the properties of quark-gluon plasma (QGP) and the phase diagram of strongly interacting matter. Event-by-event fluctuations of net electric charge in pp collisions at $\sqrt{s} = 13$ and $13.6$ TeV and for OO, Ne-Ne, and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.36$ TeV are studied by analysing the data collected by the ALICE detector at CERN Large Hadron Collider. The analysis is carried out in terms of the variable $\nu_{\mathrm{dyn}}[+,-]$, chosen for its robustness against detector efficiency losses. The observed dependence of $\nu_{\mathrm{dyn}}[+,-]$ on the charged-particle density shows a smooth, energy-independent decrease in the magnitude of $\nu_{\mathrm{dyn}}[+,-]$ from smaller to larger collision systems. The negative values of $\nu_{\mathrm{dyn}}[+,-]$ indicate a dominance of correlations between oppositely charged particle pairs compared with those arising from like-sign charge pairs. Since $\nu_{\mathrm{dyn}}[+,-]$ is known to have an intrinsic dependence on multiplicity, an appropriate scaling is applied. The variable is therefore scaled with the mean multiplicities, $\frac{1}{\frac{1}{\langle N_+ \rangle} + \frac{1}{\langle N_- \rangle}}$. The dependence of the scaled values of $\nu_{\mathrm{dyn}}[+,-]$ on charged particle density is also looked into. The results are compared with model calculations from PYTHIA, EPOS4, AMPT and HIJING.
Read the full abstract

Tuesday 6 October

Nuclear Experiment · Cross-listed from physics.ins-det

A Differentiable Surrogate for Loss-Dominated Ion Beam Transport

Jose M. Munoz-Arias, Laura Ruiz-Arango, Derick Gonzalez-Acevedo et al. (+3 more)

Radioactive nuclei with extreme proton-to-neutron ratios provide unique probes of nuclear structure, fundamental symmetries, astrophysical processes, and applications such as medicine. However, their short half-lives and low production rates mean that experiments must work with few desired ions, often amid contaminant backgrounds exceeding the signal by six orders of magnitude. Efficiently isolating, transporting, and delivering these ions through multi-stage apparatus is therefore a central challenge. We introduce a differentiable probabilistic surrogate for ion-beam transport in regimes dominated by particle loss. The model jointly captures the survival probability of ions along the beamline and the evolving phase-space distribution of the surviving particles by combining discrete-time survival analysis with conditional normalizing flows. Applied to a high-dimensional electrostatic beamline, the resulting likelihood enables gradient-based optimization of operating voltages and inference of beam properties from sparse detector observations. Once trained, the surrogate provides millisecond-scale differentiable predictions, transforming particle-tracking simulations with hard losses into an inference-ready model for experimental design, beamline optimization, and future digital twins of experiments with rare nuclei.
Read the full abstract

All authors Jose M. Munoz-Arias, Laura Ruiz-Arango, Derick Gonzalez-Acevedo, Fabian C. Pastrana-Cruz, Jackson Hacias, Ronald F. Garcia Ruiz