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The polarization of the $\mathrm{\Lambda }$and $\overline{\mathrm{\Lambda }}$hyperons along the beam direction has been measured in proton-lead ( $p\text{-Pb}$) collisions at a center-of-mass energy per nucleon pair of 8.16 TeV. The data were obtained with the CMS detector at the LHC and correspond to an integrated luminosity of $186.0\pm 6.5{\mathrm{nb}}^{-1}$. A significant azimuthal dependence of the hyperon polarization, characterized by the second-order Fourier sine coefficient $P_{z,\mathrm{s}2}$, is observed. The $P_{z,\mathrm{s}2}$values decrease as a function of charged particle multiplicity, but increase with transverse momentum. A hydrodynamic model that describes the observed $P_{z,\mathrm{s}2}$values in nucleus-nucleus collisions by introducing vorticity effects does not reproduce either the sign or the magnitude of the $p\text{-Pb}$results. These observations pose a challenge to the current theoretical implementation of spin polarization in heavy ion collisions and offer new insights into the origin of spin polarization in hadronic collisions at LHC energies. 

Charged hadron elliptic anisotropies ( $v_2$) are presented over a wide transverse momentum ( $p_{\mathrm{T}}$) range for proton-lead ( $p\mathrm{Pb}$) and lead-lead (PbPb) collisions at nucleon-nucleon center-of-mass energies of 8.16 and 5.02 TeV, respectively. The data were recorded by the CMS experiment and correspond to integrated luminosities of 186 and $0.607{\mathrm{nb}}^{-1}$for the $p\mathrm{Pb}$and PbPb systems, respectively. A four-particle cumulant analysis is performed using subevents separated in pseudorapidity to effectively suppress noncollective effects. At high $p_{\mathrm{T}}$( $p_{\mathrm{T}}>8\mathrm{GeV}$), significant positive $v_2$values that are similar between $p\mathrm{Pb}$and PbPb collisions at comparable charged particle multiplicities are observed. This observation suggests a common origin for the multiparticle collectivity for high- $p_{\mathrm{T}}$particles in the two systems. 

A<sc>bstract</sc> The jet axis decorrelation in inclusive jets is studied using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The jet axis decorrelation is defined as the angular difference between two definitions of the jet axis. It is obtained by applying two recombination schemes on all the constituents of a given jet reconstructed by the anti-k_Tsequential algorithm with a distance parameter ofR= 0.4. The data set, corresponding to an integrated luminosity of 0.66 nb⁻¹, was collected in 2018 with the CMS detector at the CERN LHC. The jet axis decorrelations are examined across collision centrality selections and intervals of jet transverse momentum. A centrality dependent evolution of the measured distributions is observed, with a progressive narrowing seen in more central events. This narrowing could result from medium-induced modification of the internal jet structure or reflect color charge effects in energy loss. This new measurement probes jet substructure in previously unexplored kinematic domains and show great promise for providing new insights on the color charge dependence of energy loss to jet-quenching models. 

Abstract The TOTEM Roman pot detectors are used to reconstruct the transverse momentum of scattered protons and to estimate the transverse location of the primary interaction. This paper presents new methods of track reconstruction, measurements of strip-level detection efficiencies, cross-checks of the LHC beam optics, and detector alignment techniques, along with their application in the selection of signal collision events. The track reconstruction is performed by exploiting hit cluster information through a novel method using a common polygonal area in the intercept-slope plane. The technique is applied in the relative alignment of detector layers with μm precision. A tag-and-probe method is used to extract strip-level detection efficiencies. The alignment of the Roman pot system is performed through time-dependent adjustments, resulting in a position accuracy of 3 μm in the horizontal and 60 μm in the vertical directions. The goal is to provide an optimal reconstruction tool for central exclusive physics analyses based on the high-β* data-taking period at √(s) = 13 TeV in 2018. 

A<sc>bstract</sc> The production cross sections of$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$and B⁺mesons are reported in proton-proton (pp) collisions recorded by the CMS experiment at the CERN LHC with a center-of-mass energy of 5.02 TeV. The data sample corresponds to an integrated luminosity of 302 pb⁻¹. The cross sections are based on measurements of the$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$→J/ψ(μ⁺μ⁻)ϕ(1020)(K⁺K⁻) and B⁺→J/ψ(μ⁺μ⁻)K⁺decay channels. Results are presented in the transverse momentum (p_T) range 7–50 GeV/cand the rapidity interval |y|<2.4 for the B mesons. The measuredp_T-differential cross sections of B⁺and$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$in pp collisions are well described by fixed-order plus next-to-leading logarithm perturbative quantum chromodynamics calculations. Using previous PbPb collision measurements at the same nucleon-nucleon center-of-mass energy, the nuclear modification factors,R_AA, of the B mesons are determined. Forp_T>10 GeV/c, both mesons are found to be suppressed in PbPb collisions (withR_AAvalues significantly below unity), with less suppression observed for the$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$mesons. In thisp_Trange, theR_AAvalues for the B⁺mesons are consistent with those for inclusive charged hadrons and D⁰mesons. Below 10 GeV/c, both B⁺and$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$are found to be less suppressed than either inclusive charged hadrons or D⁰mesons, with the$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$R_AAvalue consistent with unity. TheR_AAvalues found for the B⁺and$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$are compared to theoretical calculations, providing constraints on the mechanism of bottom quark energy loss and hadronization in the quark-gluon plasma, the hot and dense matter created in ultrarelativistic heavy ion collisions. 

Abstract Computing demands for large scientific experiments, such as the CMS experiment at the CERN LHC, will increase dramatically in the next decades. To complement the future performance increases of software running on central processing units (CPUs), explorations of coprocessor usage in data processing hold great potential and interest. Coprocessors are a class of computer processors that supplement CPUs, often improving the execution of certain functions due to architectural design choices. We explore the approach of Services for Optimized Network Inference on Coprocessors (SONIC) and study the deployment of this as-a-service approach in large-scale data processing. In the studies, we take a data processing workflow of the CMS experiment and run the main workflow on CPUs, while offloading several machine learning (ML) inference tasks onto either remote or local coprocessors, specifically graphics processing units (GPUs). With experiments performed at Google Cloud, the Purdue Tier-2 computing center, and combinations of the two, we demonstrate the acceleration of these ML algorithms individually on coprocessors and the corresponding throughput improvement for the entire workflow. This approach can be easily generalized to different types of coprocessors and deployed on local CPUs without decreasing the throughput performance. We emphasize that the SONIC approach enables high coprocessor usage and enables the portability to run workflows on different types of coprocessors.