Thu·Jun 5, 2025Thursday·June 5, 2025

1. 01*

   Quenching of single-particle strength inferred from nucleon-removal transfer reactions on ${}^{15}$C

   Y. C. Jiang (1 and 2)🇨🇳 · J. Chen (1 and 3)🇨🇳 · B. P. Kay (3)🇺🇸 · C. R. Hoffman (3)🇺🇸 · T. L. Tang (3)🇺🇸 · I. A. Tolstukhin (3)🇺🇸 · M. R. Xie (4 and 5)🇨🇳 · J. G. Li (4 and 5)🇨🇳 · N. Michel (4 and 5)🇨🇳 · M. L. Avila (3)🇺🇸 · Y. Ayyad (6)🇪🇸 · D. Bazin (7)🇺🇸 and 15 other authors

   The difference in the proton and neutron separation energies ($\Delta S$) of the weakly bound ${}^{15}$C ground state is -19.86 MeV, an extreme value. Data from intermediate-energy heavy-ion induced (HI-induced) knockout reactions on nuclei spanning $-20\lesssim \Delta S\lesssim +20$ MeV, suggest that the degree to which single-particle strength is quenched, $R{}_{\mathrm{s}}$, has a negative correlation with $\Delta S$, decreasing from unity around $-20$~MeV to around 0.2 at $+20$~MeV. For the ${}^{15}$C ground state ($R_s=0.96(4)$ in HI-induced knockout), contrasting results have recently been obtained via the neutron-adding transfer reaction, which reveal a value of $R_s=0.64(15)$, similar to the value observed at modest $\Delta S$ and more extreme values of $\Delta S$ with reaction probes other than HI knockout. In order to explore the any potential differences between $adding$ and $removing$ processes in transfer reactions at extreme $\Delta S$, single-neutron removal transfer reactions on ${}^{15}$C were performed at 7.1MeV/u in inverse kinematics. The removal of a valence neutron in 2$s_{1/2}$ orbit using both ($p$,$d$) and ($d$,$t$) reactions shows consistent quenching factors and agrees with those from the neutron-adding reaction. The present results, which can be compared with neutron knockout reaction, suggest that correlations, represented by the quenching factor, show limited dependence on neutron-proton asymmetry under the most extreme asymmetry conditions so far achieved in transfer reactions.

   nucl-exPLB(2025)·5 citations
2. 02*

   Electron-antineutrino spectrum from precision measurements of ${}^{144}$Pr-decay

   A.V. Derbin🇷🇺 · I.S. Drachnev🇷🇺 · D.V. Ivanov🇷🇺 · I.M. Kotina🇷🇺 · V.N. Muratova🇷🇺 · N.V. Niyazova🇷🇺 · D.A. Semenov🇷🇺 · M.V. Trushin🇷🇺 · E.V. Unzhakov🇷🇺

   The ${}^{144}$Ce -- ${}^{144}$Pr electron antineutrino source is one of the most suitable radiochemical sources for experiments searching for the oscillations of active neutrinos to the light sterile state. In the current work the $\beta$-spectra of ${}^{144}\mathrm{Ce}$ -- ${}^{144}\mathrm{Pr}$ source have been measured by two types of $\beta$-spectrometers based on silicon Si(Li) detectors in order to determine the energy spectrum of electron anti-neutrino emitted in the $\beta$-decay of ${}^{144}\mathrm{Pr}$ nuclei. The nuclear shape factor of the ground state beta transition in ${}^{144}\mathrm{Pr}-{}^{144}\mathrm{Nd}$ has been obtained with high precision: $C(W)=1+(-0.0301\pm 0.0007)W+(-0.101\pm 0.006)W^{-1}$. The reduced cross section for the inverse beta decay reaction on hydrogen for the ${}^{144}\mathrm{Pr}$ electron anti-neutrino source has been defined as $(4.7344\pm 0.0006_{\mathrm{stat}}\pm 0.013_{\mathrm{syst}})\times 10^{-44}\mathrm{c}{\mathrm{m}}^2{\mathrm{decay}}^{-1}$ that provides sufficient sensitivity to search for a sterile neutrino with a mass of $m_4\sim 1$~eV and a mixing angle $Si{n}^2(2{\theta }_{14})\sim 0.005$ using standard disappearance method.

   nucl-exhep-exhep-phPRD(2025)·0 citations
3. 03*

   Event Topology Classifiers at the Large Hadron Collider

   Suraj Prasad🇮🇳 · Sushanta Tripathy🇸🇪 · Bhagyarathi Sahoo🇮🇳 · Raghunath Sahoo🇮🇳

   Event classifiers are the most fundamental observables to probe the event topology of hadronic and nuclear collisions at relativistic energies. Over the last five decades, significant progress has been made to establish suitable event classifiers to probe different physics processes occurring in elementary $e^{+}{e}^{-}$ to heavy-ion collisions in a broad range of center of mass energies. One of the major motivations to revisit event classifiers at the Large Hadron Collider (LHC) originates from the recent measurements of high multiplicity proton-proton collisions, which have revealed that these small collision systems exhibit features similar to the formation of quark-gluon plasma (QGP), traditionally believed to be only achievable in heavy nucleus-nucleus collisions at ultra-relativistic energies. To pinpoint the origin of these QGP-like phenomena with substantially reduced autocorrelation and selection biases, and to bring all collision systems on equal footing, along with charged-particle multiplicity, lately several event topology classifiers such as transverse sphericity, transverse spherocity, relative transverse activity classifier, and charged-particle flattenicity have been used extensively in experiments as well as in the phenomenological front. In addition, the infrared and collinear safety of event-shape observables makes them ideal for precision studies of jets and heavy-flavors at the LHC. In this review article, we summarise the motivation, scope, and practical use of these event-shape observables. The discussion integrates results and insights from all major LHC experiments, setting the stage for precision investigations for Run 3, Run 4, and future high luminosity upgrades of the LHC.

   ↳ hep-phhep-exhep-thnucl-ex+1Phys.Rept.(2026)·17 citations
4. 04*

   The influence of nuclear short range correlations on sub-threshold particle production in proton-nucleus collisions

   Tom Reichert🇩🇪 · Jörg Aichelin🇫🇷

   The apparent production of (multi-)strange baryons and mesons at sub-threshold energies in proton-heavy ion collisions is a consequence of short range correlations (SRC), which have recently been observed in lepton-nucleus scattering. They may enhance the available center of mass energy of individual nucleon-nucleon collisions and allow, therefore, for sub-threshold particle production in proton-nucleus collisions. Calculations demonstrate that SRC enhance the probability for particle production at nominal sub-threshold energies up to a factor of $\times 10^3$ as compared to a simple Fermi gas model. We benchmark the idea by calculating the ${\Xi }^{-}$ multiplicity in nominal sub-threshold p+Nb collisions which compare well with the data measured by the HADES collaboration. These findings are of prime relevance for upcoming experiments at the FAIR facility, especially for the study of charmed hadrons.

   ↳ nucl-thnucl-exPLB(2026)·5 citations
5. 05*

   Accessing proton number fluctuations in limited regions of phase space

   Piotr Bozek🇵🇱

   In heavy ion collisions particle distributions fluctuate from event to event. It is interesting to study local fluctuations of a specific particle specie, e.g. baryons, in the transverse plane. Fluctuations of the harmonic flow provide an integrated measure of such fluctuations. An alternative approach is to study proton number fluctuations measured in a relatively narrow azimuthal angle window. Due to the transverse flow, particles registered in a narrow azimuthal angle window are emitted predominantly from a region of the fireball located at the same azimuthal angle. Similarly, it is informative to measure the covariance of the number of protons emitted in two opposite windows of azimuthal angles. The main difficulty lies in distinguishing effects of local baryon density fluctuations in the transverse plane from global particle density and collective flow fluctuations. These global volume and flow fluctuations can be estimated using some reference particles, e.g. charged mesons. Reliable estimates of such fluctuations can be constructed both for the second factorial cumulant of the proton number in an azimuthal angle window and for the covariance between two such windows. The simultaneous measurement of both quantities provides a sensitive probe of local baryon number fluctuations superimposed on top of a fluctuating fireball background density.

   ↳ nucl-thhep-phnucl-exPRC(2026)·0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.