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  1. Free, publicly-accessible full text available January 1, 2026
  2. 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.

     
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    Free, publicly-accessible full text available December 1, 2025
  3. A<sc>bstract</sc>

    A measurement is performed of Higgs bosons produced with high transverse momentum (pT) via vector boson or gluon fusion in proton-proton collisions. The result is based on a data set with a center-of-mass energy of 13 TeV collected in 2016–2018 with the CMS detector at the LHC and corresponds to an integrated luminosity of 138 fb1. The decay of a high-pTHiggs boson to a boosted bottom quark-antiquark pair is selected using large-radius jets and employing jet substructure and heavy-flavor taggers based on machine learning techniques. Independent regions targeting the vector boson and gluon fusion mechanisms are defined based on the topology of two quark-initiated jets with large pseudorapidity separation. The signal strengths for both processes are extracted simultaneously by performing a maximum likelihood fit to data in the large-radius jet mass distribution. The observed signal strengths relative to the standard model expectation are$$ {4.9}_{-1.6}^{+1.9} $$4.91.6+1.9and$$ {1.6}_{-1.5}^{+1.7} $$1.61.5+1.7for the vector boson and gluon fusion mechanisms, respectively. A differential cross section measurement is also reported in the simplified template cross section framework.

     
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    Free, publicly-accessible full text available December 1, 2025
  4. The first observation of the concurrent production of twoJ/ψmesons in proton-nucleus collisions is presented. The analysis is based on a proton-lead (pPb) data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16 TeV by the CMS experiment at the CERN LHC and corresponding to an integrated luminosity of174.6nb1. The twoJ/ψmesons are reconstructed in theirμ+μdecay channels with transverse momentapT>6.5GeVand rapidity|y|<2.4. Events where one of theJ/ψmesons is reconstructed in the dielectron channel are also considered in the search. ThepPbJ/ψJ/ψ+Xprocess is observed with a significance of 5.3 standard deviations. The measured inclusive fiducial cross section, using the four-muon channel alone, isσ(pPbJ/ψJ/ψ+X)=22.0±8.9(stat)±1.5(syst)nb. A fit of the data to the expected rapidity separation for pairs ofJ/ψmesons produced in single (SPS) and double (DPS) parton scatterings yieldsσSPSpPbJ/ψJ/ψ+X=16.5±10.8(stat)±0.1(syst)nbandσDPSpPbJ/ψJ/ψ+X=5.4±6.2(stat)±0.4(syst)nb, respectively. This latter result can be transformed into a lower bound on the effective DPS cross section, closely related to the squared average interparton transverse separation in the collision, ofσeff>1.0mbat 95% confidence level.

    © 2024 CERN, for the CMS Collaboration2024CERN 
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    Free, publicly-accessible full text available November 1, 2025
  5. A<sc>bstract</sc>

    Diboson production in association with jets is studied in the fully leptonic final states, pp → (Z/γ*)(Z/γ*) + jets → 22′ + jets, (,′ = e orμ) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb1collected with the CMS detector at the LHC. Differential distributions and normalized differential cross sections are measured as a function of jet multiplicity, transverse momentumpT, pseudorapidityη, invariant mass and ∆ηof the highest-pTand second-highest-pTjets, and as a function of invariant mass of the four-lepton system for events with various jet multiplicities. These differential cross sections are compared with theoretical predictions that mostly agree with the experimental data. However, in a few regions we observe discrepancies between the predicted and measured values. Further improvement of the predictions is required to describe the ZZ+jets production in the whole phase space.

     
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    Free, publicly-accessible full text available October 1, 2025
  6. A<sc>bstract</sc>

    A search for Higgs boson pair (HH) production in association with a vector boson V (W or Z boson) is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb1. Both hadronic and leptonic decays of V bosons are used. The leptons considered are electrons, muons, and neutrinos. The HH production is searched for in the$$ \textrm{b}\overline{\textrm{b}}\textrm{b}\overline{\textrm{b}} $$bb¯bb¯decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set at 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling,kλ, assumingk2V= 1, and vice versa on the coupling of two Higgs bosons with two vector bosons,k2V. The observed (expected) 95% confidence intervals of these coupling modifiers are37.7 <kλ< 37.2 (30.1 <kλ< 28.9) and12.2 <k2V< 13.5 (7.2 <k2V< 8.9), respectively.

     
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    Free, publicly-accessible full text available October 1, 2025
  7. Free, publicly-accessible full text available October 1, 2025
  8. A search for collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged particles using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy ofs=13TeV, corresponding to an integrated luminosity of138fb1. Jets are reconstructed with the anti-kTalgorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity|ηjet|<1.6. Two-particle correlations among the charged particles within the jets are studied as functions of the particles’ azimuthal angle and pseudorapidity separations (Δϕ*andΔη*) in a jet coordinate basis, where particles’η*,ϕ*are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up toNchj100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for|Δη*|>2. For low-Nchjjets, the long-range elliptic anisotropic harmonic,v2*, is observed to decrease withNchj. This trend is well described by Monte Carlo event generators. However, a rising trend forv2*emerges atNchj80, hinting at a possible onset of collective behavior, which is not reproduced by the models tested. This observation yields new insights into the dynamics of jet evolution in the vacuum.

    <supplementary-material><permissions><copyright-statement>© 2024 CERN, for the CMS Collaboration</copyright-statement><copyright-year>2024</copyright-year><copyright-holder>CERN</copyright-holder></permissions></supplementary-material></sec> </div> <a href='#' class='show open-abstract' style='margin-left:10px;'>more »</a> <a href='#' class='hide close-abstract' style='margin-left:10px;'>« less</a> <div class="actions" style="padding-left:10px;"> <span class="reader-count"> Free, publicly-accessible full text available September 1, 2025</span> </div> </div><div class="clearfix"></div> </div> </li> <li> <div class="article item document" itemscope itemtype="http://schema.org/TechArticle"> <div class="item-info"> <div class="title"> <a href="https://par.nsf.gov/biblio/10537271-measurement-multijet-azimuthal-correlations-determination-strong-coupling-proton-proton-collisions-sqrt-text-te-hspace-text" itemprop="url"> <span class='span-link' itemprop="name">Measurement of multijet azimuthal correlations and determination of the strong coupling in proton-proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$</span> </a> </div> <div> <strong> <a class="misc external-link" href="https://doi.org/10.1140/epjc/s10052-024-13116-7" target="_blank" title="Link to document DOI">https://doi.org/10.1140/epjc/s10052-024-13116-7  <span class="fas fa-external-link-alt"></span></a> </strong> </div> <div class="metadata"> <span class="authors"> <span class="author" itemprop="author">Hayrapetyan, A</span> <span class="sep">; </span><span class="author" itemprop="author">Tumasyan, A</span> <span class="sep">; </span><span class="author" itemprop="author">Adam, W</span> <span class="sep">; </span><span class="author" itemprop="author">Andrejkovic, J W</span> <span class="sep">; </span><span class="author" itemprop="author">Bergauer, T</span> <span class="sep">; </span><span class="author" itemprop="author">Chatterjee, S</span> <span class="sep">; </span><span class="author" itemprop="author">Damanakis, K</span> <span class="sep">; </span><span class="author" itemprop="author">Dragicevic, M</span> <span class="sep">; </span><span class="author" itemprop="author">Hussain, P S</span> <span class="sep">; </span><span class="author" itemprop="author">Jeitler, M</span> <span class="sep">; </span><span class="author">et al</span></span> <span class="year">( <time itemprop="datePublished" datetime="2024-08-01">August 2024</time> , The European Physical Journal C) </span> </div> <div style="cursor: pointer;-webkit-line-clamp: 5;" class="abstract" itemprop="description"> <title>Abstract

    A measurement is presented of a ratio observable that provides a measure of the azimuthal correlations among jets with large transverse momentum$$p_{\textrm{T}}$$pT. This observable is measured in multijet events over the range of$$p_{\textrm{T}} = 360$$pT=360$$3170\,\text {Ge}\hspace{-.08em}\text {V} $$3170GeVbased on data collected by the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13$$\,\text {Te}\hspace{-.08em}\text {V}$$TeV, corresponding to an integrated luminosity of 134$$\,\text {fb}^{-1}$$fb-1. The results are compared with predictions from Monte Carlo parton-shower event generator simulations, as well as with fixed-order perturbative quantum chromodynamics (pQCD) predictions at next-to-leading-order (NLO) accuracy obtained with different parton distribution functions (PDFs) and corrected for nonperturbative and electroweak effects. Data and theory agree within uncertainties. From the comparison of the measured observable with the pQCD prediction obtained with the NNPDF3.1 NLO PDFs, the strong coupling at the Z boson mass scale is$$\alpha _\textrm{S} (m_{{\textrm{Z}}}) =0.1177 \pm 0.0013\, \text {(exp)} _{-0.0073}^{+0.0116} \,\text {(theo)} = 0.1177_{-0.0074}^{+0.0117}$$αS(mZ)=0.1177±0.0013(exp)-0.0073+0.0116(theo)=0.1177-0.0074+0.0117, where the total uncertainty is dominated by the scale dependence of the fixed-order predictions. A test of the running of$$\alpha _\textrm{S}$$αSin the$$\,\text {Te}\hspace{-.08em}\text {V}$$TeVregion shows no deviation from the expected NLO pQCD behaviour.

     
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    Free, publicly-accessible full text available August 1, 2025
  9. A<sc>bstract</sc>

    Measurements of the charge-dependent two-particle angular correlation function in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of$$ \sqrt{s_{\textrm{NN}}} $$sNN= 8.16 TeV and lead-lead (PbPb) collisions at$$ \sqrt{s_{\textrm{NN}}} $$sNN= 5.02 TeV are reported. The pPb and PbPb data sets correspond to integrated luminosities of 186 nb1and 0.607 nb1, respectively, and were collected using the CMS detector at the CERN LHC. The charge-dependent correlations are characterized by balance functions of same- and opposite-sign particle pairs. The balance functions, which contain information about the creation time of charged particle pairs and the development of collectivity, are studied as functions of relative pseudorapidity (∆η) and relative azimuthal angle (∆ϕ), for various multiplicity and transverse momentum (pT) intervals. A multiplicity dependence of the balance function is observed in ∆ηand ∆ϕfor both systems. The width of the balance functions decreases towards high-multiplicity collisions in the momentum region<2 GeV, for pPb and PbPb results. Integrals of the balance functions are presented in both systems, and a mild dependence of the charge-balancing fractions on multiplicity is observed. No multiplicity dependence is observed at higher transverse momentum. The data are compared withhydjet,hijing, andamptgenerator predictions, none of which capture completely the multiplicity dependence seen in the data. The comparison of results with different center-of-mass energies suggests that the balance functions become narrower at higher energies, which is consistent with the idea of delayed hadronization and the effect of radial flow.

     
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    Free, publicly-accessible full text available August 1, 2025