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1. J/ψ production at midrapidity in p-Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 8.16 TeV

   https://doi.org/10.1007/JHEP07(2023)137  

   Acharya, S. ; Adamová, D. ; Adler, A. ; Aglieri Rinella, G. ; Agnello, M. ; Agrawal, N. ; Ahammed, Z. ; Ahmad, S. ; Ahn, S. U. ; Ahuja, I. ; et al ( July 2023 , Journal of High Energy Physics)

   The production of inclusive, prompt and non-prompt J/ψwas studied for the first time at midrapidity (−1.37< y_cms<0.43) in p-Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 8.16 TeV with the ALICE detector at the LHC. The inclusive J/ψmesons were reconstructed in the dielectron decay channel in the transverse momentum (p_T) interval 0< p_T<14 GeV/cand the prompt and non-prompt contributions were separated on a statistical basis forp_T>2 GeV/c. The study of the J/ψmesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13μb⁻¹. The proton-proton reference cross section for inclusive J/ψwas obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing thep_T-differential J/ψproduction cross sections. Thep_T-differential nuclear modification factorsR_pPbof inclusive, prompt, and non-prompt J/ψare consistent with unity and described by theoretical models implementing only nuclear shadowing.

    

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2. Prompt and non-prompt J/ψ production at midrapidity in Pb–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV

   https://doi.org/10.1007/JHEP02(2024)066  

   Acharya, S ; Adamová, D ; Aglieri_Rinella, G ; Agnello, M ; Agrawal, N ; Ahammed, Z ; Ahmad, S ; Ahn, S U ; Ahuja, I ; Akindinov, A ; et al ( February 2024 , Journal of High Energy Physics)

   The transverse momentum (p_T) and centrality dependence of the nuclear modification factorR_AAof prompt and non-prompt J/ψ, the latter originating from the weak decays of beauty hadrons, have been measured by the ALICE collaboration in Pb–Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV. The measurements are carried out through the e⁺e⁻decay channel at midrapidity (|y| < 0.9) in the transverse momentum region 1.5 <p_T< 10 GeV/c. Both prompt and non-prompt J/ψmeasurements indicate a significant suppression forp_T> 5 GeV/c, which becomes stronger with increasing collision centrality. The results are consistent with similar LHC measurements in the overlappingp_Tintervals, and cover the kinematic region down top_T= 1.5 GeV/cat midrapidity, not accessible by other LHC experiments. The suppression of prompt J/ψin central and semicentral collisions exhibits a decreasing trend towards lower transverse momentum, described within uncertainties by models implementing J/ψproduction from recombination of c and$$ \overline{\textrm{c}} $$$\overline{c}$quarks produced independently in different partonic scatterings. At high transverse momentum, transport models including quarkonium dissociation are able to describe the suppression for prompt J/ψ. For non-prompt J/ψ, the suppression predicted by models including both collisional and radiative processes for the computation of the beauty-quark energy loss inside the quark-gluon plasma is consistent with measurements within uncertainties.

    

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3. Measurements of the azimuthal anisotropy of prompt and nonprompt charmonia in PbPb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV

   https://doi.org/10.1007/JHEP10(2023)115  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Damanakis, K. ; Dragicevic, M. ; Escalante Del Valle, A. ; Hussain, P. S. ; Jeitler, M. ; et al ( October 2023 , Journal of High Energy Physics)

   The second-order (v₂) and third-order (v₃) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/ψ, as well as prompt ψ(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of$$ \sqrt{s_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb⁻¹recorded with the CMS detector. The J/ψ and ψ(2S) mesons are reconstructed using their dimuon decay channel. Thev₂andv₃coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measuredv₂values for prompt J/ψ mesons are found to be larger than those for nonprompt J/ψ mesons. The prompt J/ψv₂values at highp_Tare found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/ψ mesonv₃and prompt ψ(2S)v₂andv₃values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions.

    

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4. Energy dependence of coherent photonuclear production of J/ψ mesons in ultra-peripheral Pb-Pb collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ = 5.02 TeV

   https://doi.org/10.1007/JHEP10(2023)119  

   Acharya, S ; Adamová, D ; Adler, A ; Aglieri_Rinella, G ; Agnello, M ; Agrawal, N ; Ahammed, Z ; Ahmad, S ; Ahn, S U ; Ahuja, I ; et al ( October 2023 , Journal of High Energy Physics)

   The cross section for coherent photonuclear production of J/ψis presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of$$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV. Cross sections are presented in five different J/ψrapidity ranges within |y| < 4, with the J/ψreconstructed via its dilepton decay channels. In some events the J/ψis not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 <W_γPb,n< 920 GeV, whereW_γPb,nis the centre-of-mass energy per nucleon of theγPb system. This range corresponds to a Bjorken-xinterval spanning about three orders of magnitude: 1.1 × 10⁻⁵<x< 3.3 × 10⁻². In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies.

    

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5. UV Study of the Fourth Positive Band System of CO and O i 135.6 nm From Electron Impact on CO and CO 2

   https://doi.org/10.1029/2018JA026308  

   Ajello, J. M. ; Malone, C. P. ; Evans, J. S. ; Holsclaw, G. M. ; Hoskins, A. C. ; Jain, S. K. ; McClintock, W. E. ; Liu, X. ; Veibell, V. ; Deighan, J. ; et al ( April 2019 , Journal of Geophysical Research: Space Physics)

   We have measured the 30 and 100 eV far ultraviolet (FUV) emission cross sections of the optically allowed Fourth Positive Group (4PG) band system (A¹Π → X¹Σ⁺) of CO and the optically forbidden O (⁵S^o → ³P) 135.6 nm atomic transition by electron‐impact‐induced‐fluorescence of CO and CO₂. We present a model excitation cross section from threshold to high energy for theA¹Π state, including cascade by electron impact on CO. TheA¹Π state is perturbed by triplet states leading to an extended FUV glow from electron excitation of CO. We derive a model FUV spectrum of the 4PG band system from dissociative excitation of CO₂, an important process observed on Mars and Venus. Our unique experimental setup consists of a large vacuum chamber housing an electron gun system and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission Imaging Ultraviolet Spectrograph optical engineering unit, operating in the FUV (110–170 nm). The determination of the total Oi(⁵S^o) at 135.6 nm emission cross section is accomplished by measuring the cylindrical glow pattern of the metastable emission from electron impact by imaging the glow intensity about the electron beam from nominally zero to ~400 mm distance from the electron beam. The study of the glow pattern of Oi(135.6 nm) from dissociative excitation of CO and CO₂indicates that the Oi(⁵S^o) state has a kinetic energy of ~1 eV by modeling the radial glow pattern with the published lifetime of 180 μs for the Oi(⁵S^o) state.

    

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