Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV (vol 78, 509, 2018)

Diboson production in association with jets is studied in the fully leptonic final states, pp (Z)(Z/)+jets 22+jets, ( = e or ) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb collected with the CMS detector at the LHC. Differential distributions and normalized differential cross sections are measured as a function of jet multiplicity, transverse momentum , pseudorapidity , invariant mass and of the highest- and second-highest- jets, 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.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed. These improvements will allow iRPC detector to cope with higher background rates. A new Front-End-Board (FEB) is designed to readout iRPC signals with a threshold as low as 30 fC and an integrated Time Digital Converter with a resolution of 30 ps. In addition, the communication bandwidth is significantly increased by using optical fibers. The history, final design, certification, and calibration of this FEB are presented.

The inclusive jet cross section is measured as a function of jet transverse momentum and rapidity . The measurement is performed using proton-proton collision data at = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb. The jets are reconstructed with the anti- algorithm using a distance parameter of = 0.4, within the rapidity interval $\lvert y\rvert$ 2, and across the kinematic range 0.06 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling .

A search for ``emerging jets'' produced in proton-proton collisions at a center-of-mass energy of 13 TeV is performed using data collected by the CMS experiment corresponding to an integrated luminosity of 138 fb. This search examines a hypothetical dark quantum chromodynamics (QCD) sector that couples to the standard model (SM) through a scalar mediator. The scalar mediator decays into an SM quark and a dark sector quark. As the dark sector quark showers and hadronizes, it produces long-lived dark mesons that subsequently decay into SM particles, resulting in a jet, known as an emerging jet, with multiple displaced vertices. This search looks for pair production of the scalar mediator at the LHC, which yields events with two SM jets and two emerging jets at leading order. The results are interpreted using two dark sector models with different flavor structures, and exclude mediator masses up to 1950 (1850) GeV for an unflavored (flavor-aligned) dark QCD model. The unflavored results surpass a previous search for emerging jets by setting the most stringent mediator mass exclusion limits to date, while the flavor-aligned results provide the first direct mediator mass exclusion limits to date.

Physics Letters B

Measurements of the elliptic (v 2) and triangular (v 3) azimuthal anisotropy coefficients are presented for Image 1 mesons produced in Image 2 hadron decays (nonprompt Image 1 mesons) in lead-lead collisions at s NN= 5.02 TeV. The results are compared with previously published charm meson anisotropies measured using prompt Image 1 mesons. The data were collected with the CMS detector in 2018 with an integrated luminosity of 0.58 nb− 1. Azimuthal anisotropy is sensitive to the interactions of quarks with the hot and dense medium created in heavy ion collisions. Comparing results for prompt and nonprompt Image 1 mesons can assist in understanding the mass dependence of these interactions. The nonprompt results show lower magnitudes of v 2 and v 3 and weaker dependences on the meson transverse momentum and collision centrality than those found for prompt Image 1 mesons. The results are …

Physical Review Letters

A search is reported for near-threshold structures in the Formula Presented invariant mass spectrum produced in proton-proton collisions at Formula Presented from data collected by the CMS experiment, corresponding to an integrated luminosity of Formula Presented. Three structures are found, and a model with quantum interference among these structures provides a good description of the data. A new structure is observed with a local significance above 5 standard deviations at a mass of Formula Presented. Another structure with even higher significance is found at a mass of Formula Presented, which is consistent with the Formula Presented resonance reported by the LHCb experiment and confirmed by the ATLAS experiment. Evidence for another new structure, with a local significance of 4.7 standard deviations, is found at a mass of Formula Presented. Results are also reported for a model without interference, which does not fit the data as well and shows mass shifts up to 150 MeV relative to the model with interference.

A search for the production of long-lived particles in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC is presented. The search is based on data collected by the CMS experiment in 2016-2018, corresponding to a total integrated luminosity of 137 fb. This search is designed to be sensitive to long-lived particles with mean proper decay lengths between 0.1 and 1000 m, whose decay products produce a final state with at least one displaced vertex and missing transverse momentum. A machine learning algorithm, which improves the background rejection power by more than an order of magnitude, is applied to improve the sensitivity. The observation is consistent with the standard model background prediction, and the results are used to constrain split supersymmetry (SUSY) and gauge-mediated SUSY breaking models with different gluino mean proper decay lengths and masses. This search is the first CMS search that shows sensitivity to hadronically decaying long-lived particles from signals with mass differences between the gluino and neutralino below 100 GeV. It sets the most stringent limits to date for split-SUSY models and gauge-mediated SUSY breaking models with gluino proper decay length less than 6 m.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

In view of the High Luminosity LHC, the CMS Muon system will be upgraded to sustain its efficient muon triggering and reconstruction performance. Resistive Plate Chambers (RPC) are dedicated detectors for muon triggering due to their excellent timing resolution. The RPC system will be extended up to 2.4 in pseudorapidity. Before the LHC Long Shutdown 3, new RE3/1 and RE4/1 stations of the forward Muon system will be equipped with improved Resistive Plate Chambers (iRPC) having, compared to the present RPC system, a different design and geometry and 2D strip readout. This advanced iRPC geometry configuration allows the rate capability to improve and hence survive the harsh background conditions during the HL-LHC phase. Several iRPC demonstrator chambers were installed in CMS during the recently completed 2nd Long Shutdown to study the detector behaviour under real LHC conditions …

A test of lepton flavor universality in B K and B Kee decays, as well as a measurement of differential and integrated branching fractions of a nonresonant B K decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions at = 13 TeV recorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractions (B K) to (B Kee) is determined from the measured double ratio (K) of these decays to the respective branching fractions of the B J/K with J/ and ee decays, which allow for significant cancellation of systematic uncertainties. The ratio (K) is measured in the range 1.1 6.0 GeV, where is the invariant mass of the lepton pair, and is found to be (K) = 0.78, in agreement with the standard model expectation (K) 1. This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the same range, (B K) = (12.42 0.68) 10, is consistent with the present world-average value and has a comparable precision.

Physica Scripta

In the current study, an ab initio derivation of the neutron self-shielding factor to solve the complex neutron transport problem of the decrease of the neutron flux as it penetrates into a material placed in an isotropic neutron field having equal flux in all directions. The theory of steady-state neutron transport was employed, starting from Stuart’s formula, to derive simple analytical formulae based on the integral cross-section parameters. The formulae could be adopted by the user according to various variables, such as the neutron flux distribution and geometry of the simulation at hand. The concluded formulae of the self-shielding factors comprise an inverted sigmoid function normalized with a weight representing the ratio between the macroscopic total and scattering cross-sections of the medium. The general convex volume geometries are reduced to a set of chord lengths, while the neutron interaction probabilities …

arXiv preprint arXiv:2403.09430

A search for Higgs boson pair (HH) production with one Higgs boson decaying to two bottom quarks and the other to two W bosons are presented. The search is done using proton-proton collisions data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb recorded by the CMS detector at the LHC from 2016 to 2018. The final states considered include at least one leptonically decaying W boson. No evidence for the presence of a signal is observed and corresponding upper limits on the HH production cross section are derived. The limit on the inclusive cross section of the nonresonant HH production, assuming that the distributions of kinematic observables are as expected in the standard model (SM), is observed (expected) to be 14 (18) times the value predicted by the SM, at 95% confidence level. The limits on the cross section are also presented as functions of various Higgs boson coupling modifiers, and anomalous Higgs boson coupling scenarios. In addition, limits are set on the resonant HH production via spin-0 and spin-2 resonances within the mass range 250-900 GeV.

A new tracking detector will be installed as part of the Phase-2 upgrade of the CMS detector for the high-luminosity LHC era. This tracking detector includes the Inner Tracker, equipped with silicon pixel sensor modules, and the Outer Tracker, consisting of modules with two parallel stacked silicon sensors. The Outer Tracker front-end ASICs will be able to correlate hits from charged particles in these two sensors to perform on-module discrimination of transverse momenta (????T). The ????T information is generated at a frequency of 40 MHz and will be used in the Level-1 trigger decision of CMS. Prototypes of the so-called 2S modules were tested at the Test Beam Facility at DESY Hamburg between 2019 and 2020. These modules use the final front-end ASIC, the CMS Binary Chip (CBC), and for the first time the Concentrator Integrated Circuit (CIC), optical readout and on-module power conversion. In total, seven modules were tested, one of which was assembled with sensors irradiated with protons. An important aspect was to show that it is possible to read out modules synchronously. A cluster hit efficiency of about 99.75% was achieved for all modules. The CBC ????T discrimination mechanism has been verified to work together with the CIC and optical readout. The measured module performance meets the requirements for operation in the upgraded CMS tracking detector.

Addition of a single additive (such as biochar or calcium) in anaerobic digestion has been studied previously. However, the effect of combined additives in anaerobic digestion (including fat, oil, and grease) has not been well-investigated yet. In this study, the biogas/biomethane, lipid degradation, and volatile fatty acids were investigated under various concentrations of combined additives. The effect on principal reactions, microbial community, and functional enzymes was also analyzed under different concentrations of calcium-modified biochar. The fat, oil, and grease was degraded up to 81.91 % resulting in 9.03-fold higher biomethane production. Acidogenesis and methanogenesis efficiencies were induced up to 53.31 % and 67.91 %, respectively, due to the enrichment of bacteria (such as Clostridium >50 %, Sporosarcina >18 %, Cellulosilyticum >8 %) and archaea (such as Methanosphaera >49 %). Increased …

arXiv preprint arXiv:2403.01173

In 2018, the E12-17-003 experiment was conducted at the Thomas Jefferson National Accelerator Facility (JLab) to explore the possible existence of an nnLambda state in the reconstructed missing mass distribution from a tritium gas target. As part of this investigation, data was also collected using a gaseous hydrogen target, not only for a precise absolute mass scale calibration but also for the study of Lambda/Sigma^0 electroproduction. This dataset was acquired at Q^2~0.5 (GeV/c)^2, W=2.14 GeV, and theta_{gamma K}^{c.m.}~8 deg. It covers forward angles where photoproduction data is scarce and a low-Q^2 region that is of interest for hypernuclear experiments. On the other hand, this kinematic region is at a slightly higher Q^2 than previous hypernuclear experiments, thus providing crucial information for understanding the Q^2 dependence of the differential cross sections for Lambda/Sigma^0 hyperon electroproduction. This paper reports on the Q^2 dependence of the differential cross section for the e + p -> e' + K^+ + Lambda/Sigma^0 reaction in the 0.2-0.8 (GeV/c)^2, and provides comparisons with the currently available theoretical models.

Diboson production in association with jets is studied in the fully leptonic final states, pp (Z)(Z/)+jets 22+jets, ( = e or ) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb collected with the CMS detector at the LHC. Differential distributions and normalized differential cross sections are measured as a function of jet multiplicity, transverse momentum , pseudorapidity , invariant mass and of the highest- and second-highest- jets, 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.

Physics Letters B

Measurements of the elliptic (v 2) and triangular (v 3) azimuthal anisotropy coefficients are presented for Image 1 mesons produced in Image 2 hadron decays (nonprompt Image 1 mesons) in lead-lead collisions at s NN= 5.02 TeV. The results are compared with previously published charm meson anisotropies measured using prompt Image 1 mesons. The data were collected with the CMS detector in 2018 with an integrated luminosity of 0.58 nb− 1. Azimuthal anisotropy is sensitive to the interactions of quarks with the hot and dense medium created in heavy ion collisions. Comparing results for prompt and nonprompt Image 1 mesons can assist in understanding the mass dependence of these interactions. The nonprompt results show lower magnitudes of v 2 and v 3 and weaker dependences on the meson transverse momentum and collision centrality than those found for prompt Image 1 mesons. The results are …

A search for pair production of scalar and vector leptoquarks (LQs) each decaying to a muon and a bottom quark is performed using proton-proton collision data collected at 13 TeV with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 138 fb . No excess above standard model expectation is observed. Scalar (vector) LQs with masses less than 1810 (2120) GeV are excluded at 95% confidence level, assuming a 100% branching fraction of the LQ decaying to a muon and a bottom quark. These limits represent the most stringent to date.

Chinese Journal of Physics

Observation indicates that many nearby galaxies host supermassive central black holes. We use the Bardeen black holes in four-dimensional Einstein-Gauss–Bonnet (4D EGB) gravity, with additional parameters-the coupling constant α ̃ and charge q, as central black holes in various galaxies to investigate gravitational lensing properties in strong field regime. Taking the supermassive black holes Sgr A* and M87* as the lens, we compare observable signatures of 4D EGB Bardeen black holes with those of the Schwarzschild black holes. In the case of 4D EGB Bardeen black holes we observed that he angular position θ∞ for Sgr A*∈(23.19, 25.56) μ as, whereas for M87* it is∈(17.94, 19.78) μ as. Further, the angular separation s, which is an increasing function of α ̃ and q for Sgr A* and M87* differs significantly, respectively, in (0.032, 0.15) μ as and (0.025, 0.115) μ as. The deviations of the lensing observables Δ θ …

The first observation of the decay (2S) and measurement of the branching ratio of (2S) to J/ are presented. The J/ and (2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb. The branching fraction ratio is measured to be ((2S))/( J/) = 0.84 (stat) 0.10 (syst) 0.02 (), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the baryon mass and natural width are also presented, using the final state, where the baryon is reconstructed through the decays J/, (2S), J/K, and J/K. Finally, the fraction of the baryons produced from decays is determined.

A search for partonic collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged constituents using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy of = 13 TeV, corresponding to an integrated luminosity of 138 fb. Jets are reconstructed with the anti- algorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity $\lvert\eta\rvert$ 1.6. Two-particle correlations among the charged constituents within the jets are studied as functions of the particles' azimuthal angle and pseudorapidity separations ( and ) in a jet coordinate basis, where constituents' , are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up to 100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for $\lvert\Delta\eta^*\rvert$ 2. For low-multiplicity jets, the long-range elliptic anisotropic harmonic, , is observed to decrease with . This trend is well described by Monte Carlo event generators. However, a rising trend for emerges at 80, 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 parton fragmentation processes in the vacuum.

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

Hadrons are systems of quarks bound by the strong interaction, described at the fundamental level by quantum chromodynamics (QCD). The production and decay of hadrons involve the nonperturbative regime of QCD, making calculations challenging. Much progress has been made in recent years in experimental and theoretical studies of beauty mesons, with the aim of testing the Standard Model and

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

This paper presents a study of Z→ llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb− 1 collected at a centre-ofmass energy

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

This paper presents a study of Z→ llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb− 1 collected at a centre-ofmass energy

European Physical Journal C

This paper presents a study of Z→ llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb− 1 collected at a centre-ofmass energy

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

Hadrons are systems of quarks bound by the strong interaction, described at the fundamental level by quantum chromodynamics (QCD). The production and decay of hadrons involve the nonperturbative regime of QCD, making calculations challenging. Much progress has been made in recent years in experimental and theoretical studies of beauty mesons, with the aim of testing the Standard Model and

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

This paper presents a study of Z→ llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb− 1 collected at a centre-ofmass energy

European Physical Journal C

This paper presents a study of Z→ llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb− 1 collected at a centre-ofmass energy

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

The inclusive Higgs boson production crosssection is measured in the di-photon and the ZZ∗→ 4l decay channels using 31.4 and 29.0 fb− 1 of pp collision data respectively, collected with the ATLAS detector at a centreof-mass energy of

European Physical Journal C

Towards a muon collider (vol 83, 864, 2023) English Français login Menu Search Browse Collections Help English Français login Infoscience Towards a muon collider (vol 83, 864, 2023) Accettura, Carlotta; Adams, Dean; Agarwal, Rohit; Ahdida, Claudia; Aime, Chiara; Amapane, Nicola; Amorim, David; Andreetto, Paolo; Anulli, Fabio; Appleby, Robert; Apresyan, Artur; Apyan, Aram; Arsenyev, Sergey; Asadi, Pouya; Mahmoud, Mohammed Attia; Azatov, Aleksandr; Back, John; Balconi, Lorenzo; Bandiera, Laura; Barlow, Roger; Bartosik, Nazar; Barzi, Emanuela; Batsch, Fabian; Bauce, Matteo; Berg, J. Scott; Bersani, Andrea; Bertarelli, Alessandro; Bertolin, Alessandro; Black, Kevin; Boattini, Fulvio; Bogacz, Alex; Bonesini, Maurizio; Bordini, Bernardo; Bottaro, Salvatore; Bottura, Luca; Braghieri, Alessandro; Breschi, Marco; Bruhwiler, Natalie; Buffat, Xavier; Buonincontri, Laura; Burrows, Philip N.; Burt, Graeme; Buttazzo, …

European Physical Journal C

This paper presents a study of Z→ llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb− 1 collected at a centre-ofmass energy