Fri·Mar 28, 2025Friday·March 28, 2025

1. 01*

   MPD physics performance studies in Bi+Bi collisions at $\sqrt{s_{NN}}=9.2$ GeV

   MPD Collaboration

   The Multi-Purpose Detector (MPD) is one of the three experiments of the Nuclotron Ion Collider-fAcility (NICA) complex, which is currently under construction at the Joint Institute for Nuclear Research in Dubna. With collisions of heavy ions in the collider mode, the MPD will cover the energy range 4-11 GeV to scan the high baryon-density region of the QCD phase diagram. With expected statistics of 50-100 million events collected during the first run, MPD will be able to study a number of observables, including measurements of light hadrons and hypernuclei production, particle flow, correlations and fluctuations, have a first look at dielectron production, and modification of vector-meson properties in dense matter. In this paper, we present selected results of the physics feasibility studies for the MPD experiment in Bismuth-Bismuth collisions at an energy of 9.2 GeV, the system considered as one of the first available at the NICA collider.

   nucl-exhep-phnucl-thRev.Mex.Fis.(2025)·25 citations
2. 02*

   First study of polarized proton-proton scattering with small-$x$ helicity evolution

   Daniel Adamiak🇺🇸 · Nicholas Baldonado🇺🇸 · Yuri V. Kovchegov🇺🇸 · Ming Li🇺🇸 · W. Melnitchouk🇺🇸 · Daniel Pitonyak🇺🇸 · Nobuo Sato🇺🇸 · Matthew D. Sievert🇺🇸 · Andrey Tarasov🇺🇸 · Yossathorn Tawabutr🇫🇮

   We perform a phenomenological study of helicity-dependent parton distribution functions (PDFs) using small-$x$ helicity evolution equations, incorporating for the first time single-inclusive jet production data in polarized proton-proton ($pp$) scattering at parton momentum fractions $x<0.1$. We also simultaneously include double-longitudinal spin asymmetries in inclusive and semi-inclusive deep-inelastic scattering probing $x<0.1$. Employing the polarized small-$x$ pure-glue calculation of $pp\to gX$ for the jet production cross section, we modify the large-$N_c\&N_f$ KPS-CTT evolution equations by setting $N_f=0$ to replicate the large-$N_c$ (pure-glue) limit, while retaining external quark flavors for the spinor field operators. We find that the $pp$ data have a considerable impact on the helicity PDFs at small $x$, reducing their uncertainties and leading to a total quark and gluon helicity in the proton for $x<0.1$ of $-0.04\pm 0.23$. Combining our analysis with the a recent JAM helicity PDF analysis of the world polarized data, which includes $x>0.1$, we find a total quark and gluon helicity contribution for $x>10^{-7}$ of between 0.02 and 0.51.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2025)·12 citations
3. 03*

   Global analysis of fragmentation functions to light neutral hadrons

   Jun Gao🇨🇳 · ChongYang Liu🇨🇳 · Mengyang Li🇨🇳 · XiaoMin Shen🇨🇳 · Hongxi Xing🇨🇳 · Yuxiang Zhao🇨🇳 · Yiyu Zhou🇮🇹

   Fragmentation functions (FFs) are crucial non-perturbative components in quantum chromodynamics (QCD), playing a vital role in predictions and understanding of the hadronization process. In this paper, we present the FFs for $K_S^0$, $\eta$, ${\pi }^0$ mesons, and $\Lambda$ baryons in the context of global QCD analysis. The data included in the fit are from single inclusive $e^{+}{e}^{-}$ annihilation (SIA), semi-inclusive deep-inelastic scattering (SIDIS) and proton-proton collisions, with kinematic cuts carefully applied to ensure validity of collinear factorization and perturbative QCD expansion. For the first time, data from SIDIS and hadron-in-jet production in SIA have been incorporated into the extraction of FFs for light-flavor neutral hadrons. Our analysis reveals that these data play a critical role in constraining the gluon distribution, and in distinguishing between different quark flavors. Pulls from different datasets are also studied by performing alternative fits with systematically subtracting groups of data from the nominal fit. For the quality of the fit, good ${\chi }^2$ values are achieved for most of the datasets, and FFs are generally well constrained within the momentum fraction region $\text{pqty}0.1,0.5$. The extracted $K_S^0$ fragmentation functions, together with the $K_S^0$ FFs constructed from $K^{\pm }$ FFs via isospin symmetry, are used to test isospin symmetry in kaon fragmentation. Although a definitive conclusion cannot be reached yet, these studies have identified several potential measurements that can be performed at existing facilities, which may ultimately help us to arrive at a conclusive answer. With the comprehensive species of FFs extracted within the NPC framework, we are able to perform a test on the momentum sum rule with the light-flavor charged and neutral hadrons.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2025)·19 citations
4. 04*

   The impact of future $D$- and $B$-meson measurements with the SMOG2 program at LHCb on the determination of nuclear parton distribution functions

   Carlo Flore🇮🇹 · Cynthia Hadjidakis🇫🇷 · Daniel Kikoła🇵🇱 · Aleksander Kusina🇵🇱 · Anton Safronov🇵🇱

   We perform an analysis of the potential impact of future $D$- and $B$-meson measurement within the SMOG2 fixed-target program at the LHCb experiment on nuclear parton distribution functions. Following~\cite{Bursche:2018orf}, we assume that SMOG2 will collect data for five nuclear targets: He, Ne, Ar, Kr, Xe and hydrogen which will provide a baseline for constructing nuclear ratios. The analysis is performed by using the PDF reweighting method. We demonstrate that such a measurement will allow to considerably reduce the current uncertainties of the nuclear gluon distribution and, to some extent, even the uncertainties of the light sea-quark distributions. Furthermore, it will provide the first possibility to systematically study the current assumptions on the $A$-dependence of the nuclear parton distributions.

   ↳ hep-phhep-exhep-thnucl-ex+1PLB(2025)·2 citations
5. 05*

   Visualizing How Jet Structure Shapes Jet Wakes

   Arjun Srinivasan Kudinoor🇺🇸 · Daniel Pablos🇪🇸 · Krishna Rajagopal🇺🇸

   The ATLAS Collaboration has developed a method to analyze large-radius jets composed of skinny $R=0.2$ subjets in heavy-ion collisions. We first demonstrate that the measurements pioneered by ATLAS constrain the value of $L_{\mathrm{res}}$, the resolution length of QGP -- and rule out any picture in which an entire parton shower loses energy coherently as a single entity. We then analyze the response of the medium to the passage of large-radius $R=2$ jets containing two skinny subjets in gamma-jet events. We introduce novel jet-shape observables that allow us to visualize how the internal structure of large-radius jets shapes the wakes they excite in the QGP. We find that even when the subjets are $\sim 0.8$ radians apart, the angular shape of the soft hadrons originating from their wake forms a single broad structure. Only when the two subjets are even farther apart are two sub-wakes revealed. We show that the way in which jet structure shapes the structure of jet-induced wakes can be visualized with similar clarity in experiments by using only low-$p_T$ hadrons. The observables we introduce offer a new and distinctive way of seeing jet-induced wakes -- and wake substructure -- in heavy-ion collision data.

   ↳ hep-phnucl-exnucl-thEPJ Web Conf.(2025)·1 citation
6. 06*

   High efficiency quantification of ${}^{90}$Sr contamination in cow milk after a nuclear accident

   Q. Rogliardo · A. Kanellakopoulos🇧🇪 · H. Corcelle · M. Fedel · M. Zsely-Schaffter · G. Triscone · S. Pallada

   Monitoring ${}^{90}$Sr contamination in milk following a nuclear accident is critical due to its radiotoxicity and calcium-mimicking behaviour, leading to accumulation in bones and teeth. This study presents a high-efficiency protocol for quantifying${}^{90}$Sr in cow milk by integrating freeze-drying, high-temperature calcination, ion exchange chromatography and liquid scintillation spectroscopy (LSC). The method was validated using reference milk samples with 0.45~Bq/mL of ${}^{90}$Sr, achieving a chemical yield of 100 $\pm$ 2\%, ensuring near-complete recovery and accurate quantification. The minimum detectable activity (MDA) was estimated at 0.33 Bq/L under optimal conditions, demonstrating the protocol's sensitivity for low-level detection. A comparative analysis with existing methods centrifugation-based approaches and Dowex resin techniques revealed that our protocol outperforms in both strontium recovery and organic matter elimination. Alternative methods showed lower recovery rates (68 $\pm$ 2\% for Guérin's method, 65 $\pm$6\% for Dowex resin) and suffered from procedural drawbacks, such as incomplete organic matter removal. Applying this methodology to compare samples from certified laboratories confirmed its robustness, with liquid scintillation spectroscopy radioactivity values doubling after 14 days, consistent with secular equilibrium between ${}^{90}$Sr and ${}^{90}$Y. While the protocol is optimized for milk, future research should explore its applicability to other food matrices. The high yield, reliability, and ease of implementation position this method as an effective tool for nuclear emergency response and routine radiological monitoring.

   ↳ physics.chem-phnucl-exAppl.Radiat.Isot.(2025)·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.