Nuclear Theory·nucl-th

Friday·January 30, 2026

9 papers—5 primary·4 cross-listed

01
Chiral interactions and superfluidity in the calcium isotopic chain
A. Scalesi🇸🇪 · A. Ekström🇸🇪 · C. Forssén🇸🇪 · G. Hagen🇺🇸
We perform ab initio calculations of three-point mass differences in the odd- and even-mass $^{39 - 49}$ Ca isotopes to probe nuclear superfluidity via empirical neutron pairing gaps. We also quantify the sensitivity of those gaps to the parameters of the interaction at mean-field level. Recent studies employing accurate chiral nuclear interactions have found these gaps to be too small. We show that experimental values can be reproduced at mean-field level by substantially increasing the attraction of the singlet $S$ -wave two-nucleon contact interaction, but doing so induces an unphysical bound state of the di-neutron. The sensitivity of these predictions to the full calibration of the nuclear interaction is then studied by performing Bayesian posterior sampling in a delta-full chiral effective field theory at third chiral order. We find that pairing gaps remain largely unaffected, leaving the explanation of nuclear superfluidity as a future task for improved many-body modeling and refined interactions at higher chiral orders.
nucl-thPRC(2026)·2 citations
02
The Silver Blaze Problem in QCD
Thomas D. Cohen🇺🇸
This article provides a pedagogical introduction to the Silver Blaze problem. This problem refers to the difficulty of reconciling to perspectives on QCD with a chemical potential. The first is the phenomenological fact that at $T = 0$ QCD remains in its ground state -- the vacuum -- with all physical observables unchanged whenever the magnitude of a chemical potential is less than some critical value. The second is the fact that in functional integral treatments, the inclusion of any nonzero chemical potential changes all eigenvalues of the Dirac operator for every gauge configuration, leading to a natural expectation that the functional determinants also changes, which leads to the expectation that physical observables should be altered. The problem amounts to explaining why nothing happens below the critical chemical potential. By focusing on the eigenvalues of $γ_{0}$ times the Dirac operator rather than the Dirac operator itself, it is possible to show that for QCD with two flavors and identical quark masses, an isospin chemical potential with a magnitude less than $m_{π}$ (and no baryon chemical potential), or a baryon chemical potential of less than $\frac{3}{2} m_{π}$ (and no isospin chemical potential), the functional integerals at $T = 0$ themselves remain unchanged in all configurations that contribute to the functional integral with non-vanishing weight. However, for $μ_{crit} μ_{B} > \frac{3}{2} m_{π}$ , the Silver Blaze phenomenon arises due to functional determinants having nontrivial phases that lead to cancellations between different gauge configurations. The mechanism leading to such cancellations remains unknown.
nucl-thhep-lathep-ph3 citations
03
Chemical potential differentials in the QCD phase diagram from heavy-ion isobar collisions
Joaquin Grefa🇺🇸 · Chun Yue Tsang🇺🇸 · Rajesh Kumar🇺🇸 · Veronica Dexheimer🇺🇸 · Claudia Ratti🇺🇸 · Zhangbu Xu🇺🇸
Temperature and baryon, charge, and strangeness chemical potentials characterize QCD matter under extreme conditions. Differences between these chemical potentials and their ratios probe conserved-charge correlations and the system's response in the multidimensional QCD phase diagram. We extract these quantities from STAR Ru+Ru and Zr+Zr isobar collisions using a Bayesian thermal analysis of hadron yields, which substantially reduces systematic uncertainties, and compare them with Taylor-expanded lattice-QCD and Chiral Mean Field model predictions. Isobar collisions thus emerge as a precision probe of four-dimensional QCD thermodynamics.
nucl-thhep-exhep-lathep-ph+15 citations
04
Competing decay modes and stability analysis of superheavy nuclei with Z = 120 using relativistic mean-field approach
Nishu Jain · M. Bhuyan · P. Mohr · Raj Kumar
We systematically study the competition between {\alpha}-decay and spontaneous fission in even-even superheavy nuclei with (Z=120) and 256 \leq A \leq 304 within the preformed cluster-decay model using microscopic inputs from relativistic mean-field calculations with the NL3 parameter set. The {\alpha}-decay half-lives are obtained from WKB barrier penetration with empirically determined preformation factors, self-consistent Q_{\alpha} values from RMF, and nuclear interaction potentials constructed using both M3Y and relativistic R3Y nucleon-nucleon forces, and are benchmarked against standard semi-empirical formulas. Our results predict reduced spontaneous fission probabilities and extended {\alpha}-decay chains toward the fermium region for isotopes with 296 \leq A \leq 304, with enhanced stability reflected in maxima of log_{10} T_{1/2} around neutron numbers N \approx 166-182. In particular, the nuclei 296,298,300,302,304_{120} are identified as the most favorable candidates for survival against fission, demonstrating the crucial role of shell effects, deformation, and pairing correlations and providing quantitative guidance for future experimental searches of Z=120 nuclei.
nucl-thNPA(2026)·0 citations
05
Cone-Dependent Jet Collisional Energy Loss in Finite QCD Medium
Magdalena Djordjevic🇷🇸 · Bojana Ilic🇷🇸 · Marko Djordjevic🇷🇸
We derive a compact HTL-resummed expression for the leading-order jet collisional energy loss in a finite-size, finite-temperature QCD medium. Defining the jet energy inside a cone of radius $R$ , we obtain the out-of-cone elastic energy loss with an explicit separation between contributions from the primary jet parton and recoiling medium partons. The result reproduces the known partonic limit as $R \to 0$ , vanishes for $R \to π$ , and applies to both light- and heavy-flavor jets. Numerically, the elastic component shows a pronounced non-linear $R$ dependence relative to the radiative baseline, and its importance increases with $R$ , becoming comparable to or exceeding the radiative contribution for sufficiently large jet radii. The path-length dependence remains close to linear for all $R$ , while the medium-response contribution can exceed $10%$ for realistic jet radii.
nucl-thhep-phPLB(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Chiral interactions and superfluidity in the calcium isotopic chain

The Silver Blaze Problem in QCD

Chemical potential differentials in the QCD phase diagram from heavy-ion isobar collisions

Competing decay modes and stability analysis of superheavy nuclei with Z = 120 using relativistic mean-field approach

Cone-Dependent Jet Collisional Energy Loss in Finite QCD Medium

Affiliations