Mon·Apr 25, 2022Monday·April 25, 2022

1. 01*

   Measurement of beauty-strange meson production in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV via non-prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ mesons

   ALICE Collaboration

   The production yields of non-prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ mesons, namely ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ mesons from beauty-hadron decays, were measured for the first time as a function of the transverse momentum ($p_{\mathrm{T}}$) at midrapidity ($|y|<0.5$) in central and semi-central Pb$-$Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE experiment at the LHC. The ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ mesons and their charge conjugates were reconstructed from the hadronic decay channel ${{\mathrm{D}}_{\mathrm{s}}}^{+}\to \varphi {\pi }^{+}$, with $\varphi \to {\mathrm{K}}^{-}{\mathrm{K}}^{+}$, in the $4<p_{\mathrm{T}}<36$ GeV/$c$ and $2<p_{\mathrm{T}}<24$ GeV/$c$ intervals for the 0$-$10% and 30$-$50% centrality classes, respectively. The measured yields of non-prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ mesons are compared to those of prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ and non-prompt ${\mathrm{D}}^0$ mesons by calculating the ratios of the production yields in Pb$-$Pb collisions and the nuclear modification factor $R_{\mathrm{AA}}$. The ratio between the $R_{\mathrm{AA}}$ of non-prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ and prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ mesons, and that between the $R_{\mathrm{AA}}$ of non-prompt ${{\mathrm{D}}_{\mathrm{s}}}^{+}$ and non-prompt ${\mathrm{D}}^0$ mesons in central Pb$-$Pb collisions are found to be on average higher than unity in the $4<p_{\mathrm{T}}<12$ GeV/$c$ interval with a statistical significance of about $1.6\sigma$ and $1.7\sigma$, respectively. The measured $R_{\mathrm{AA}}$ ratios are compared with the predictions of theoretical models of heavy-quark transport in a hydrodynamically expanding QGP that incorporate hadronisation via quark recombination.

   nucl-exPLB(2023)·29 citations
2. 02*

   Underlying-event properties in pp and p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   We report about the properties of the underlying event measured with ALICE at the LHC in pp and p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The event activity, quantified by charged-particle number and summed-$p_{\mathrm{T}}$ densities, is measured as a function of the leading-particle transverse momentum ($p_{\mathrm{T}}^{\mathrm{trig}}$). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different $p_{\mathrm{T}}$ thresholds (0.15, 0.5, and 1 GeV/$c$) at mid-pseudorapidity ($|\eta |<0.8$). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p$-$Pb collisions, namely, a steep increase with $p_{\mathrm{T}}^{\mathrm{trig}}$ for low $p_{\mathrm{T}}^{\mathrm{trig}}$, followed by a saturation at $p_{\mathrm{T}}^{\mathrm{trig}}\approx 5$ GeV/$c$. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p$-$Pb collisions for $p_{\mathrm{T}}^{\mathrm{trig}}>10$ GeV/$c$, whereas for lower $p_{\mathrm{T}}^{\mathrm{trig}}$ values the event activity is slightly higher in p$-$Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators.

   nucl-exhep-exJHEP(2023)·16 citations
3. 03*

   Nuclear modification factor of neutral pions in the forward and backward regions in $p$-Pb collisions

   LHCb collaboration: R. Aaij · A.S.W. Abdelmotteleb · C. Abellan Beteta · F. Abudinén · T. Ackernley · B. Adeva · M. Adinolfi · H. Afsharnia · C. Agapopoulou · C.A. Aidala · S. Aiola · Z. Ajaltouni and 1000 other authors

   The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of $8.16\mathrm{TeV}$ with the LHCb detector. The ${\pi }^0$ production cross section is measured differentially in transverse momentum ($p_{\mathrm{T}}$) for $1.5<p_{\mathrm{T}}<10.0\mathrm{GeV}$ and in center-of-mass pseudorapidity (${\eta }_{c.m.}$) regions $2.5<{\eta }_{c.m.}<3.5$ (forward) and $-4.0<{\eta }_{c.m.}<-3.0$ (backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of ${\pi }^0$ production, while the backward measurement shows the first evidence of ${\pi }^0$ enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear collisions.

   nucl-exhep-exPRL(2023)·36 citations
4. 04*

   W${}^{\pm }$-boson production in p$-$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV and PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV

   ALICE Collaboration

   The production of the W${}^{\pm }$ bosons measured in p$-$Pb collisions at a centre-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{NN}}=8.16$ TeV and Pb$-$Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV with ALICE at the LHC is presented. The W${}^{\pm }$ bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region $-4<{\eta }_{\mathrm{lab}}^{\mu }<-2.5$ with transverse momentum $p_{\mathrm{T}}^{\mu }>10$ GeV/$c$. While in Pb$-$Pb collisions the measurements are performed in the forward ($2.5<y_{\mathrm{cms}}^{\mu }<4$) rapidity region, in p$-$Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward ($-4.46<y_{\mathrm{cms}}^{\mu }<-2.96$) and forward ($2.03<y_{\mathrm{cms}}^{\mu }<3.53$) rapidity regions. The W${}^{-}$ and W${}^{+}$ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p$-$Pb collision centrality, the production cross sections of the W${}^{-}$ and W${}^{+}$ bosons are combined and normalised to the average number of binary nucleon$-$nucleon collision $⟨N_{\mathrm{coll}}⟩$. In Pb$-$Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W${}^{\pm }$-boson cross sections in p$-$Pb and Pb$-$Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.

   nucl-exJHEP(2023)·22 citations
5. 05*

   Photoproduction of low-$p_{\mathrm{T}}$ J/$\psi$ from peripheral to central Pb$-$Pb collisions at 5.02 TeV

   ALICE Collaboration

   An excess of J/$\psi$ yield at very low transverse momentum ($p_{\mathrm{T}}<0.3$ GeV/$c$), originating from coherent photoproduction, is observed in peripheral and semicentral hadronic Pb$-$Pb collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The measurement is performed with the ALICE detector via the dimuon decay channel at forward rapidity ($2.5<y<4$). The nuclear modification factor at very low $p_{\mathrm{T}}$ and the coherent photoproduction cross section are measured as a function of centrality down to the 10% most central collisions. These results extend the previous study at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV, confirming the clear excess over hadronic production in the $p_{\mathrm{T}}$ range 0$-$0.3 GeV/$c$ and the centrality range 70$-$90%, and establishing an excess with a significance greater than 5$\sigma$ also in the 50$-$70% and 30$-$50% centrality ranges. The results are compared with earlier measurements at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV and with different theoretical predictions aiming at describing how coherent photoproduction occurs in hadronic interactions with nuclear overlap.

   nucl-exhep-exPLB(2023)·35 citations
6. 06*

   Exclusive $Z^0$ production in $ep$ and $eA$ collisions at high energies

   G. M. Peccini🇧🇷 · L. S. Moriggi🇧🇷 · M. V. T. Machado🇧🇷

   In this work the $k_{\perp }$-factorization formalism is applied to compute the exclusive $Z^0$ boson photoproduction in $ep$ and $eA$ collisions. The study is also extended to $pp$ and $AA$ processes. The nuclear effects are investigated considering heavy and light ions. Analytical models for the unintegrated gluon distribution are taken into account and the corresponding theoretical uncertainty is quantified. The analysis is done for electron-ion collisions at the Large Hadron-Electron Collider (LHeC), its high-energy upgrade (HE-LHeC) and at the Future Circular Collider (FCC) in lepton-hadron mode. Additionally, ultra-peripheral heavy ion collisions at future runs of the Large Hadron Collider (LHC) and at the FCC (hadron-hadron mode) are also considered.

   ↳ hep-phhep-exnucl-exPRD(2022)·3 citations
7. 07*

   Advances in actinide thin films: synthesis, properties, and future directions

   K. D. Vallejo🇺🇸 · F. Kabir🇺🇸 · N. Poudel🇺🇸 · C. A. Marianetti🇺🇸 · D. H. Hurley🇺🇸 · P. J. Simmonds🇺🇸 · C. A. Dennett🇺🇸 · K. Gofryk🇺🇸

   Actinide-based compounds exhibit unique physics due to the presence of 5f electrons, and serve in many cases as important technological materials. Targeted thin film synthesis of actinide materials has been successful in generating high-purity specimens in which to study individual physical phenomena. These films have enabled the study of the unique electron configuration, strong mass renormalization, and nuclear decay in actinide metals and compounds. The growth of these films, as well as their thermophysical, magnetic, and topological properties, have been studied in a range of chemistries, albeit far fewer than most classes of thin film systems. This relative scarcity is the result of limited source material availability and safety constraints associated with the handling of radioactive materials. Here, we review recent work on the synthesis and characterization of actinide-based thin films in detail, describing both synthesis methods and modelling techniques for these materials. We review reports on pyrometallurgical, solution-based, and vapor deposition methods. We highlight the current state-of-the-art in order to construct a path forward to higher quality actinide thin films and heterostructure devices.

   ↳ cond-mat.mtrl-scinucl-exphysics.atom-phquant-phRept.Prog.Phys.(2022)·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.