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1. Charm fragmentation fractions and $$\mathbf {c\overline{c}}$$ cross section in p–Pb collisions at $$\mathbf {\sqrt{s _{NN}}=5.02 TeV}$$

   https://doi.org/10.1140/epjc/s10052-024-13394-1  

   Acharya, S; Adamová, D; Agarwal, A; Aglieri_Rinella, G; Aglietta, L; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; et al (December 2024, The European Physical Journal C)

   Abstract The total charm-quark production cross section per unit of rapidity$$\textrm{d}\sigma ({{\textrm{c}}\overline{\textrm{c}}})/\textrm{d}y$$ $\text{d}\sigma \left(\text{c}\overline{\text{c}}\right)/\text{d}y$ , and the fragmentation fractions of charm quarks to different charm-hadron species$$f(\textrm{c}\rightarrow {\textrm{h}}_{\textrm{c}})$$ $f(\text{c}\to {\text{h}}_{\text{c}})$ , are measured for the first time in p–Pb collisions at$$\sqrt{s_\textrm{NN}} = 5.02~\text {Te}\hspace{-1.00006pt}\textrm{V} $$ $\sqrt{s_{\text{NN}}}=5.02\text{Te}\text{V}$ at midrapidity ($$-0.96 $-0.96<y<0.04$ in the centre-of-mass frame) using data collected by ALICE at the CERN LHC. The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species:$$\textrm{D}^{0}$$ ${\text{D}}^0$ ,$$\textrm{D}^{+}$$ ${\text{D}}^{+}$ ,$$\textrm{D}_\textrm{s}^{+}$$ ${\text{D}}_{\text{s}}^{+}$ , and$$\mathrm {J/\psi }$$ $J/\psi$ mesons, and$$\Lambda _\textrm{c}^{+}$$ ${\Lambda }_{\text{c}}^{+}$ and$$\Xi _\textrm{c}^{0}$$ ${\Xi }_{\text{c}}^0$ baryons. The resulting cross section is$$ \textrm{d}\sigma ({{\textrm{c}}\overline{\textrm{c}}})/\textrm{d}y =219.6 \pm 6.3\;(\mathrm {stat.}) {\;}_{-11.8}^{+10.5}\;(\mathrm {syst.}) {\;}_{-2.9}^{+8.3}\;(\mathrm {extr.})\pm 5.4\;(\textrm{BR})\pm 4.6\;(\mathrm {lumi.}) \pm 19.5\;(\text {rapidity shape})+15.0\;(\Omega _\textrm{c}^{0})\;\textrm{mb} $$ $\text{d}\sigma \left(\text{c}\overline{\text{c}}\right)/\text{d}y=219.6\pm 6.3\left(\mathrm{stat}.\right)_{-11.8}^{+10.5}\left(\mathrm{syst}.\right)_{-2.9}^{+8.3}\left(\mathrm{extr}.\right)\pm 5.4\left(\text{BR}\right)\pm 4.6\left(\mathrm{lumi}.\right)\pm 19.5\left(\text{rapidity shape}\right)+15.0\left({\Omega }_{\text{c}}^0\right)\text{mb}$ , which is consistent with a binary scaling of pQCD calculations from pp collisions. The measured fragmentation fractions are compatible with those measured in pp collisions at$$\sqrt{s} = 5.02$$ $\sqrt{s}=5.02$ and 13 TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and p–Pb collisions compared with$$\mathrm {e^{+}e^{-}}$$ $e^{+}{e}^{-}$ and$$\mathrm {e^{-}p}$$ $e^{-}p$ collisions. The$$p_\textrm{T}$$ $p_{\text{T}}$ -integrated nuclear modification factor of charm quarks,$$R_\textrm{pPb}({\textrm{c}}\overline{\textrm{c}})= 0.91 \pm 0.04\;\mathrm{(stat.)} ^{+0.08}_{-0.09}\;\mathrm{(syst.)} ^{+0.05}_{-0.03}\;\mathrm{(extr.)} \pm 0.03\;\mathrm{(lumi.)}$$ $R_{\text{pPb}}\left(\text{c}\overline{\text{c}}\right)=0.91\pm 0.04{(\mathrm{stat}.)}_{-0.09}^{+0.08}{(\mathrm{syst}.)}_{-0.03}^{+0.05}(\mathrm{extr}.)\pm 0.03(\mathrm{lumi}.)$ , is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions. 

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2. Measurement of the inclusive isolated-photon production cross section in pp and Pb–Pb collisions at $$\mathbf {\sqrt{\textit{s}_{NN }} = 5.02}$$ TeV

   https://doi.org/10.1140/epjc/s10052-025-13971-y  

   Acharya, S; Agarwal, A; Rinella, G Aglieri; Aglietta, L; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; et al (May 2025, The European Physical Journal C)

   Abstract The ALICE Collaboration at the CERN LHC has measured the inclusive production cross section of isolated photons at midrapidity as a function of the photon transverse momentum ($$p_{\textrm{T}}^{\gamma }$$ $p_{\text{T}}^{\gamma }$ ), in Pb–Pb collisions in different centrality intervals, and in pp collisions, at centre-of-momentum energy per nucleon pair of$$\sqrt{s_{\textrm{NN}}}~=~5.02$$ $\sqrt{s_{\text{NN}}}=5.02$  TeV. The photon transverse momentum range is between 10–14 and 40–140 GeV/$$c$$ $c$ , depending on the collision system and on the Pb–Pb centrality class. The result extends to lower$$p_{\textrm{T}}^{\gamma }$$ $p_{\text{T}}^{\gamma }$ than previously published results by the ATLAS and CMS experiments at the same collision energy. The covered pseudorapidity range is$$|\eta ^{\gamma } | <0.67$$ $|{\eta }^{\gamma }|<0.67$ . The isolation selection is based on a charged particle isolation momentum threshold$$p_{\textrm{T}}^\mathrm{iso,~ch} = 1.5$$ $p_{\text{T}}^{\mathrm{iso},\mathrm{ch}}=1.5$  GeV/$$c$$ $c$ within a cone of radii$$R=0.2$$ $R=0.2$ and 0.4. The nuclear modification factor is calculated and found to be consistent with unity in all centrality classes, and also consistent with the HG-PYTHIA model, which describes the event selection and geometry biases that affect the centrality determination in peripheral Pb–Pb collisions. The measurement is compared to next-to-leading order perturbative QCD calculations and to the measurements of isolated photons and Z$$^{0}$$ $_{}^0$ bosons from the CMS experiment, which are all found to be in agreement. 

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3. Search for CP violation in $${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ decays in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$

   https://doi.org/10.1140/epjc/s10052-024-13244-0  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (December 2024, The European Physical Journal C)

   Abstract A search is reported for charge-parity$$CP$$ $\mathrm{CP}$ violation in$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ ${\text{D}}^0\to {\text{K}}_{\text{S}}^0{\text{K}}_{\text{S}}^0$ decays, using data collected in proton–proton collisions at$$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$ $\sqrt{s}=13\text{Te}\text{V}$ recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6$$\,\text {fb}^{-1}$$ ${\text{fb}}^{-1}$ , which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays$${{{\textrm{D}}}^{{*+}}} \rightarrow {{{\textrm{D}}}^{{0}}} {{{\mathrm{\uppi }}}^{{+}}} $$ $\text{D}_{}^{\ast +}\to {\text{D}}^0{\pi }^{+}$ and$${{{\textrm{D}}}^{{*-}}} \rightarrow {\overline{{\textrm{D}}}^{{0}}} {{{\mathrm{\uppi }}}^{{-}}} $$ $\text{D}_{}^{\ast -}\to {\overline{\text{D}}}^0{\pi }^{-}$ . The$$CP$$ $\mathrm{CP}$ asymmetry in$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ ${\text{D}}^0\to {\text{K}}_{\text{S}}^0{\text{K}}_{\text{S}}^0$ is measured to be$$A_{CP} ({{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} ) = (6.2 \pm 3.0 \pm 0.2 \pm 0.8)\%$$ $A_{\mathrm{CP}}\left({\text{K}}_{\text{S}}^0{\text{K}}_{\text{S}}^0\right)=(6.2\pm 3.0\pm 0.2\pm 0.8)\%$ , where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the$$CP$$ $\mathrm{CP}$ asymmetry in the$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{{\mathrm{\uppi }}}^{{+}}} {{{\mathrm{\uppi }}}^{{-}}} $$ ${\text{D}}^0\to {\text{K}}_{\text{S}}^0{\pi }^{+}{\pi }^{-}$ decay. This is the first$$CP$$ $\mathrm{CP}$ asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state. 

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4. Measurement of isolated prompt photon production in pp and p–Pb collisions at the LHC

   https://doi.org/10.1140/epjc/s10052-025-14802-w  

   Acharya, S; Agarwal, A; Aglieri_Rinella, G; Aglietta, L; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; et al (December 2025, The European Physical Journal C)

   Abstract This paper presents the measurement of the isolated prompt photon inclusive production cross section in pp and p–Pb collisions by the ALICE Collaboration at the LHC. The measurement is performed in p–Pb collisions at centre-of-mass energies per nucleon pair of$$\sqrt{s_{\text {NN}}}={5.02}\,\textrm{TeV}$$ $\sqrt{s_{\text{NN}}}=5.02\text{TeV}$ and 8.16 TeV, as well as in pp collisions at$$\sqrt{s}={5.02}\,\textrm{TeV}$$ $\sqrt{s}=5.02\text{TeV}$ and 8 TeV. The cross section is obtained at midrapidity$$(|y|<0.7)$$ $\left(\right|y|<0.7)$ using a charged-track based isolation momentum$$p_\textrm{T}^{\text {iso,~ch}}<{1.5}\,\textrm{GeV}/c$$ $p_{\text{T}}^{\text{iso, ch}}<1.5\text{GeV}/c$ in a cone with radius$$R=0.4$$ $R=0.4$ . The data for both collision systems are well reproduced by perturbative QCD (pQCD) calculations at next-to-leading order (NLO) using recent parton distribution functions for free (PDF) and bound (nPDF) nucleons. Furthermore, the nuclear modification factor$$R_{\text {pA}}$$ $R_{\text{pA}}$ for both collision energies is consistent with unity for$$p_{\textrm{T}}$$ $p_{\text{T}}$ $$>{20}\,\textrm{GeV}/c$$ $>20\text{GeV}/c$ . However, deviations from unity ($$R_\textrm{pA}<1$$ $R_{\text{pA}}<1$ ) of up to 20% are observed for$$p_{\textrm{T}}$$ $p_{\text{T}}$ $$<{20}\,\textrm{GeV}/c$$ $<20\text{GeV}/c$ with limited significance, indicating the possible presence of nuclear effects in the initial state of the collision. The suppression increases with decreasing$$p_{\textrm{T}}$$ $p_{\text{T}}$ with a significance of$$2.3\upsigma $$ $2.3\sigma$ for a non-zero slope and yields$$R_{\textrm{pA}}<1$$ $R_{\text{pA}}<1$ with a significance of$$1.8\upsigma $$ $1.8\sigma$ at$$\sqrt{s_{\textrm{NN}}}={8.16}\,\textrm{TeV}$$ $\sqrt{s_{\text{NN}}}=8.16\text{TeV}$ for$$p_{\textrm{T}}$$ $p_{\text{T}}$ $$<{20}\,\textrm{GeV}/c$$ $<20\text{GeV}/c$ . In addition, a significance of$$1.1\upsigma $$ $1.1\sigma$ is observed for$$R_{\textrm{pA}}<1$$ $R_{\text{pA}}<1$ at the lower collision energy$$\sqrt{s_{\textrm{NN}}}={5.02}\,\textrm{TeV}$$ $\sqrt{s_{\text{NN}}}=5.02\text{TeV}$ for$$p_{\textrm{T}} < {14}\,\textrm{GeV}/c$$ $p_{\text{T}}<14\text{GeV}/c$ . The magnitude and shape of the suppression are consistent with pQCD predictions at NLO using nPDFs that incorporate nuclear shadowing effects in the Pb nucleus. 

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5. Medium-induced modification of azimuthal correlations of electrons from heavy-flavor hadron decays with charged particles in Pb–Pb collisions at $$\mathbf {\sqrt{s_{\textrm{NN}}} = 5.02}$$ TeV

   https://doi.org/10.1140/epjc/s10052-026-15412-w  

   Abualrob, I J; Acharya, S; Aglieri_Rinella, G; Aglietta, L; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahuja, I; Akbar, Z; et al (June 2026, The European Physical Journal C)

   Abstract The azimuthal-correlation distributions between electrons from the decays of heavy-flavor hadrons and associated charged particles in Pb–Pb collisions at$$\sqrt{s_{\textrm{NN}}} = 5.02$$ $\sqrt{s_{\text{NN}}}=5.02$ TeV are reported for the 0–10% and 30–50% centrality classes. This measurement provides access to the jet-like correlation observables in the heavy-flavor sector in Pb–Pb collisions. The analysis is performed for trigger electrons from heavy-flavor hadron decays with transverse momentum$$4< p_\textrm{T}^\textrm{e} < 16~\textrm{GeV}/c$$ $4<p_{\text{T}}^{\text{e}}<16\text{GeV}/c$ , considering associated particles within the transverse-momentum range$$1< p_\textrm{T}^\textrm{assoc} < 7$$ $1<p_{\text{T}}^{\text{assoc}}<7$ $$\textrm{GeV}/c$$ $\text{GeV}/c$ , and a pseudorapidity difference of$$|\Delta \eta |<1$$ $\left|\Delta \eta \right|<1$ between the trigger electron and associated particles. The per-trigger nuclear modification factor ($$I_\textrm{AA}$$ $I_{\text{AA}}$ ) is calculated to compare the near- and away-side peak yields to those in pp collisions at$$\sqrt{s} = 5.02$$ $\sqrt{s}=5.02$ TeV. In 0–10% central collisions, the$$I_\textrm{AA}$$ $I_{\text{AA}}$ indicates a hint of enhancement of associated-particle yields with$$p_\textrm{T}<3$$ $p_{\text{T}}<3$ GeV/con the near side, and a suppression of yields with$$p_\textrm{T}>4$$ $p_{\text{T}}>4$ GeV/con the away side. The$$I_\textrm{AA}$$ $I_{\text{AA}}$ for electron triggers from heavy-flavor hadron decays is compared with that for light-flavor and strange-particle triggers to investigate the dependence on different fragmentation processes and parton-medium dynamics, and is found to be the same within uncertainties. 

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