Fri·Jan 27, 2023Friday·January 27, 2023

1. 01*

   Energy Dependence of Intermittency for Charged Hadrons in Au+Au Collisions at RHIC

   STAR Collaboration: M. I. Abdulhamid🇪🇬 · B. E. Aboona🇺🇸 · J. Adam🇨🇿 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · I. Aggarwal🇮🇳 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · D. M. Anderson🇺🇸 · E. C. Aschenauer🇺🇸 · S. Aslam🇮🇳 · J. Atchison🇺🇸 and 371 other authors

   Density fluctuations near the QCD critical point can be probed via an intermittency analysis in relativistic heavy-ion collisions. We report the first measurement of intermittency in Au$+$Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 7.7-200 GeV measured by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The scaled factorial moments of identified charged hadrons are analyzed at mid-rapidity and within the transverse momentum phase space. We observe a power-law behavior of scaled factorial moments in Au$+$Au collisions and a decrease in the extracted scaling exponent ($\nu$) from peripheral to central collisions. The $\nu$ is consistent with a constant for different collisions energies in the mid-central (10-40\%) collisions. Moreover, the $\nu$ in the 0-5\% most central Au$+$Au collisions exhibits a non-monotonic energy dependence that reaches a possible minimum around $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 27 GeV. The physics implications on the QCD phase structure are discussed.

   nucl-exPLB(2023)·40 citations
2. 02*

   Measuring ${\mu }_B$ at the LHC with ALICE

   Mario Ciacco (for the ALICE Collaboration)🇮🇹

   The baryon chemical potential ${\mu }_B$ is a fundamental parameter for the statistical mechanical description of particle production in heavy-ion collisions: its value encodes the average net baryon content of the fireball at chemical freeze-out. The first ${\mu }_B$ measurement in high-energy Pb-Pb collisions at the LHC was published in 2018 in Nature, and it was found that ${\mu }_B=0.7\pm 3.8$ MeV. In this contribution, an improved ${\mu }_B$ measurement based on the study of antiparticle-to-particle ratios for protons, ${}^3\mathrm{He}$ and hypertriton (${}_{\Lambda }^3\mathrm{H}$) using the data collected by ALICE in Run 2 of the LHC, is presented. The isospin chemical potential is also determined via the ${\pi }^{-}/{\pi }^{+}$ ratio. The obtained ${\mu }_B$ represents the most precise measurement available.

   nucl-ex4 citations
3. 03*

   First measurement of the ${}^{94}$Nb($n$,$\gamma$) cross section at the CERN n\_TOF facility

   J. Balibrea-Correa · V. Babiano-Suarez · J. Lerendegui-Marco · C. Domingo-Pardo · I. Ladarescu · A. Tarifeño-Saldivia · V. Alcayne · D. Cano-Ott · E. González-Romero · T. Martínez · E. Mendoza · J. Plaza and 125 other authors

   One of the crucial ingredients for the improvement of stellar models is the accurate knowledge of neutron capture cross-sections for the different isotopes involved in the $s$-,$r$- and $i$- processes. These measurements can shed light on existing discrepancies between observed and predicted isotopic abundances and help to constrain the physical conditions where these reactions take place along different stages of stellar evolution.In the particular case of the radioactive ${}^{94}$Nb, the ${}^{94}$Nb($n$,$\gamma$) cross-section could play a role in the determination of the $s$-process production of ${}^{94}$Mo in AGB stars, which presently cannot be reproduced by state-of-the-art stellar models. There are no previous ${}^{94}$Nb($n$,$\gamma$) experimental data for the resolved and unresolved resonance regions mainly due to the difficulties in producing high-quality samples and also due to limitations in conventional detection systems commonly used in time-of-flight experiments.Motivated by this situation, a first measurement of the ${}^{94}$Nb($n$,$\gamma$) reaction was carried out at CERN n\_TOF, thereby exploiting the high luminosity of the EAR2 area in combination with a new detection system of small-volume C6D6-detectors and a high quality ${}^{94}$Nb-sample. The latter was based on hyper-pure ${}^{93}$Nb material activated at the high-flux reactor of ILL-Grenoble. An innovative ring-configuration detection system in close geometry around the capture sample allowed us to significantly enhance the signal-to-background ratio. This set-up was supplemented with two conventional C${}_6$D${}_6$ detectors and a high-resolution LaCl${}_3$(Ce)-detector, which will be employed for addressing reliably systematic effects and uncertainties.At the current status of the data analysis, 18 resonance in ${}^{94}$Nb+$n$ have been observed for the first time in the neutron energy range from thermal up to 10 keV.

   nucl-exEPJ Web Conf.(2023)·11 citations
4. 04*

   King-plot analysis of isotope shifts in simple diatomic molecules

   Michail Athanasakis-Kaklamanakis🇨🇭 · Shane G. Wilkins🇺🇸 · Alexander A. Breier🇩🇪 · Gerda Neyens🇧🇪

   We demonstrate that the isotope shift in isotopomers of diatomic molecules, where the nucleus of one of its constituent atoms is replaced by another isotope, can be expressed as the sum of a field shift and a mass shift, similar to the atomic case. We show that a linear relation holds between atomic and molecular isotopes shifts, thus extending the King-plot analysis to molecular isotope shifts. Optical isotope shifts in YbF and ZrO and infrared isotope shifts in SnH are analyzed with a molecular King-plot approach, utilizing Yb${}^{+}$ and Zr${}^{+}$ ionic isotope shifts and charge radii of Sn obtained with non-optical methods. The changes in the mean-squared nuclear charge radii $\delta ⟨r^2⟩$ of ${}^{170-174,176}$Yb and ${}^{90-92,94,96}$Zr extracted from the molecular transitions are found to be in excellent agreement with the values from the spectroscopy of Yb${}^{+}$ and Zr${}^{+}$, respectively. On the contrary, in the case of the vibrational-rotational transition in SnH, no sensitivity to the nuclear volume could be deduced within the experimental resolution, which makes it unsuitable for the extraction of nuclear charge radii but provides insights into the molecular electronic wave function not accessible via other methods. The new opportunities offered by the molecular King-plot analysis for research in nuclear structure and molecular physics are discussed.

   ↳ physics.atom-phnucl-exnucl-thphysics.atm-clusPRX(2023)·6 citations
5. 05*

   Production measurements of heavy quarks in pp collisions at $\sqrt{s}$ = 13 TeV with the ALICE detector

   Tebogo Joyce Shaba (for the ALICE collaboration)🇿🇦

   Heavy-flavour production measurements in pp collisions are important tools to test theoretical models based on perturbative quantum chromodymanics (pQCD) and to investigate the heavy-quark hadronization mechanisms. In ALICE, heavy quarks are measured via the hadronic and electronic decay channels at central rapidity (-0.9 $<$ $\text{y}$ $<$ 0.9) and via the muon decay channels at forward rapidity (-4 $<$ $\text{y}$ $<$ -2.5). In this contribution, the production cross-section measurements via the leptonic decay of heavy-flavour hadrons are presented and compared to pQCD theoretical calculations. The latest measurements of ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$, ${\mathrm{D}}^{\ast +}$, $D_s^{+}$ mesons whose hadronic decays into charged are fully reconstructed together with the measurements of ${\Lambda }_c^{+}$ , ${\Xi }_c^{0,+}$, ${\Sigma }_c^{0,++}$ and ${\Omega }_c^0$ baryons, performed with the ALICE detector at midrapidity in pp collisions at $\sqrt{s}$ = 13 TeV, are also presented. Measurements of charm-baryon production are crucial to study the charm-quark hadronization mechanisms in a partonic rich environment like the one produced in pp collisions at LHC energies.

   ↳ hep-exnucl-ex0 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.