Measurements of Higgs boson production in the decay channel with a pair of leptons in proton-proton collisions at = 13 TeV

Using proton-proton collision data corresponding to an integrated luminosity of 140 fb collected by the CMS experiment at = 13 TeV, the J/K decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the (2S) decay, is measured to be ( J/K)/( (2S)) = [3.38 1.02 0.61 0.03]%, where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in ((2S) J/) and ( ).

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.

arXiv preprint arXiv:2402.14786

We study how the recent experimental results constrain the gauge sectors of U(1) extensions of the standard model using a novel representation of the parameter space. We determine the bounds on the mixing angle between the massive gauge bosons, or equivalently, the new gauge coupling as a function of the mass of the new neutral gauge boson in the approximate range GeV/. We consider the most stringent bounds obtained from direct searches for the . We also exhibit the allowed parameter space by comparing the predicted and measured values of the parameter and those of the mass of the boson. Finally, we discuss the prospects of searches at future colliders.

Physical review letters

The first evidence for the Higgs boson decay to a Z boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision datasets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb− 1 for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is 2.2±0.7 times the standard model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.

The discovery of the Higgs boson has led to new possible signatures for heavy resonance searches at the LHC. Since then, search channels including at least one Higgs boson plus another particle have formed an important part of the program of new physics searches. In this report, the status of these searches by the CMS Collaboration is reviewed. Searches are discussed for resonances decaying to two Higgs bosons, a Higgs and a vector boson, or a Higgs boson and another new resonance, with proton-proton collision data collected at = 13 TeV in the years 2016-2018. A combination of the results of these searches is presented together with constraints on different beyond-the-standard model scenarios, including scenarios with extended Higgs sectors, heavy vector bosons and extra dimensions. Studies are shown for the first time by CMS on the validity of the narrow-width approximation in searches for the resonant production of a pair of Higgs bosons. The potential for a discovery at the High Luminosity LHC is also discussed.

The European physical journal. C, Particles and fields

The strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton–proton collisions at a center-of-mass energy of 13 Te V. The analysis uses a data sample corresponding to a total integrated luminosity of 138 fb-1 collected with the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm jets are tagged using the presence of a muon or a secondary vertex inside the jet. The W+ c production cross section and the cross section ratio R c±= σ (W++ c)/σ (W-+ c) are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in R c±= 0.950±0.005 (stat)±0.010 (syst). The …

A search for heavy neutral leptons (HNLs) decaying in the CMS muon system is presented. A data sample is used corresponding to an integrated luminosity of 138 fb of proton-proton collisions at = 13 TeV, recorded at the CERN LHC in 2016-2018. Decay products of long-lived HNLs could interact with the shielding materials in the CMS muon system and create hadronic and electromagnetic showers detected in the muon chambers. This distinctive signature provides a unique handle to search for HNLs with masses below 4 GeV and proper decay lengths of the order of meters. The signature is sensitive to HNL couplings to all three generations of leptons. Candidate events are required to contain a prompt electron or muon originating from a vertex on the beam axis and a displaced shower in the muon chambers. No significant deviations from the standard model background expectation are observed. In the electron (muon) channel, the most stringent limits to date are set for HNLs in the mass range of 2.1-3.0 (1.9-3.3) GeV, reaching mixing matrix element squared values as low as 8.6 (4.6) 10.

The European Physical Journal. C, Particles and Fields

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton–proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13\(\,\text {Te\hspace {-. 08em} V}\). Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 20 of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z …

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 .

Physical Review Letters

The first search for scalar leptoquarks produced in τ-lepton–quark collisions is presented. It is based on a set of proton-proton collision data recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb− 1. The reconstructed final state consists of a jet, significant missing transverse momentum, and a τ lepton reconstructed through its hadronic or leptonic decays. Limits are set on the product of the leptoquark production cross section and branching fraction and interpreted as exclusions in the plane of the leptoquark mass and the leptoquark-τ-quark coupling strength.

The\Xbsd decay topology, where the\Xb baryon decays to\psiXim with $\PGy\to\mumu $(upper) or\jpsiLaKm (lower), where\PGy refers to the\jpsi and\psit mesons. The distances given are the average decay lengths, .The\Xbsd decay topology, where the\Xb baryon decays to\psiXim with $\PGy\to\mumu $(upper) or\jpsiLaKm (lower), where\PGy refers to the\jpsi and\psit mesons. The distances given are the average decay lengths, .

A search for exotic decays of the Higgs boson (H) with a mass of 125 GeV to a pair of light pseudoscalars is performed in final states where one pseudoscalar decays to two b quarks and the other to a pair of muons or leptons. A data sample of proton-proton collisions at = 13 TeV corresponding to an integrated luminosity of 138 fb recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (CL) on the Higgs boson branching fraction to bb and to bb, via a pair of s. The limits depend on the pseudoscalar mass and are observed to be in the range (0.17-3.3) 10 and (1.7-7.7) 10 in the bb and bb final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine model-independent upper limits on the branching fraction (H bb) at 95% CL, with being a muon or a lepton. For different types of 2HDM+S, upper bounds on the branching fraction (H ) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, H ) values above 0.23 are excluded at 95% CL for values between 15 and 60 GeV.

arXiv preprint arXiv:2403.04584

A search for long-lived heavy neutrinos (N) in the decays of \PB mesons produced in proton-proton collisions at = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb collected in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream that enhances the number of recorded events containing B mesons. The search probes heavy neutrinos with masses in the range 1 3 GeV and decay lengths in the range 10 10 mm, where is the N proper mean lifetime. Signal events are defined by the signature B NX; N , where the leptons and can be either a muon or an electron, provided that at least one of them is a muon. The hadronic recoil system, X, is treated inclusively and is not reconstructed. No significant excess of events over the standard model background is observed in any of the invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, , and on are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit 2.010 is obtained at = 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on for masses 1 1.7 GeV are the most stringent from a collider experiment to date.

arXiv preprint arXiv:2403.20201

A measurement of the production cross section of a Higgs boson with transverse momentum greater than 250 GeV is presented where the Higgs boson decays to a pair of leptons. It is based on proton-proton collision data collected by the CMS experiment at the CERN LHC at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb. Because of the large transverse momentum of the Higgs boson the leptons from its decays are boosted and produced spatially close, with their decay products overlapping. Therefore, a dedicated algorithm was developed to reconstruct and identify them. The observed (expected) significance of the measured signal with respect to the standard model background-only hypothesis is 3.5 (2.2) standard deviations. The product of the production cross section and branching fraction is measured to be 1.64 times the standard model expectation. The fiducial differential production cross section is also measured as functions of the Higgs boson and leading jet transverse momenta. This measurement extends the probed large-transverse-momentum region beyond 600 GeV.

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.

arXiv preprint arXiv:2403.15518

The operation and performance of the Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) are presented, based on data collected in pp collisions at = 13 TeV at the CERN LHC, in the years from 2015 to 2018 (LHC Run 2), corresponding to an integrated luminosity of 151 fb. The CMS ECAL is a scintillating lead-tungstate crystal calorimeter, with a silicon strip preshower detector in the forward region that provides precise measurements of the energy and the time-of-arrival of electrons and photons. The successful operation of the ECAL is crucial for a broad range of physics goals, ranging from observing the Higgs boson and measuring its properties, to other standard model measurements and searches for new phenomena. Precise calibration, alignment, and monitoring of the ECAL response are important ingredients to achieve these goals. To face the challenges posed by the higher luminosity, which characterized the operation of the LHC in Run 2, the procedures established during the 2011-2012 run of the LHC have been revisited and new methods have been developed for the energy measurement and for the ECAL calibration. The energy resolution of the calorimeter, for electrons from Z boson decays reaching the ECAL without significant loss of energy by bremsstrahlung, was better than 1.8%, 3.0%, and 4.5% in the $\lvert\eta\rvert$ intervals [0.0,0.8], [0.8,1.5], [1.5, 2.5], respectively. This resulting performance is similar to that achieved during Run 1 in 2011-2012, in spite of the more severe running conditions.

The first search for soft unclustered energy patterns (SUEPs) is performed using an integrated luminosity of 138 fb of proton-proton collision data at = 13 TeV collected in 2016-2018 by the CMS detector at the LHC. Such SUEPs are predicted by Hidden Valley models with a new, confining force with a large 't Hooft coupling. In events with boosted topologies, selected by high-threshold hadronic triggers, the multiplicity and sphericity of clustered tracks are used to reject the background from standard model quantum chromodynamics. With no observed excess of events over the standard model expectation, limits are set on the cross section for production via gluon fusion of a scalar mediator with SUEP-like decays.

A search is described for the production of a pair of bottom-type vector-like quarks (B VLQs) with mass greater than 1000 GeV. Each B VLQ decays into a b quark and a Higgs boson, a b quark and a Z boson, or a t quark and a W boson. This analysis considers both fully hadronic final states and those containing a charged lepton pair from a Z boson decay. The products of the H bb boson decay and of the hadronic Z or W boson decays can be resolved as two distinct jets or merged into a single jet, so the final states are classified by the number of reconstructed jets. The analysis uses data corresponding to an integrated luminosity of 138 fb collected in proton-proton collisions at = 13 TeV with the CMS detector at the LHC from 2016 to 2018. No excess over the expected background is observed. Lower limits are set on the B VLQ mass at 95% confidence level. These depend on the B VLQ branching fractions and are 1570 and 1540 GeV for 100% B bH and 100% B bZ, respectively. In most cases, the mass limits obtained exceed previous limits by at least 100 GeV.

A search for exotic decays of the Higgs boson (H) with a mass of 125 GeV to a pair of light pseudoscalars is performed in final states where one pseudoscalar decays to two b quarks and the other to a pair of muons or leptons. A data sample of proton-proton collisions at = 13 TeV corresponding to an integrated luminosity of 138 fb recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (CL) on the Higgs boson branching fraction to bb and to bb, via a pair of s. The limits depend on the pseudoscalar mass and are observed to be in the range (0.17-3.3) 10 and (1.7-7.7) 10 in the bb and bb final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine model-independent upper limits on the branching fraction (H bb) at 95% CL, with being a muon or a lepton. For different types of 2HDM+S, upper bounds on the branching fraction (H ) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, H ) values above 0.23 are excluded at 95% CL for values between 15 and 60 GeV.

The European physical journal. C, Particles and fields

The strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton–proton collisions at a center-of-mass energy of 13 Te V. The analysis uses a data sample corresponding to a total integrated luminosity of 138 fb-1 collected with the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm jets are tagged using the presence of a muon or a secondary vertex inside the jet. The W+ c production cross section and the cross section ratio R c±= σ (W++ c)/σ (W-+ c) are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in R c±= 0.950±0.005 (stat)±0.010 (syst). The …

The European Physical Journal C

This work investigates static and dynamical quark star properties within a holographic model. We solve the Tolman–Oppenheimer–Volkoff equations for the quark matter equation of state obtained from the brane configuration. We determine the mass-radius diagram for a range of model parameters and compare with recent NICER observational data for the pulsars PSR J and PSR J Motivated by the GW170817 event detected by the LIGO-Virgo collaboration, we also calculate the tidal deformability parameter obtained for each component of the binary star system. We show that quark stars composed of flavor-independent quark matter derived from the holographic model are not able to satisfy simultaneously the LIGO-Virgo and NICER astrophysical bounds.

The European Physical Journal C

The inclusive Higgs boson production cross-section is measured in the di-photon and the decay channels using 31.4 and 29.0 fb of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of  . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are   fb, and   fb, in agreement with the corresponding Standard Model predictions of  fb and  fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of  pb and  pb at 13.6  from the di-photon and  …

The European Physical Journal C

Measurements of the differential production cross-sections of prompt and non-prompt and mesons with transverse momenta between 8 and 360 GeV and rapidity in the range are reported. Furthermore, measurements of the non-prompt fractions of and , and the prompt and non-prompt -to- production ratios, are presented. The analysis is performed using 140 fb of  TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018.

The European Physical Journal C

A search for the production of single-top-quarks in association with missing energy is performed in proton–proton collisions at a centre-of-mass energy of with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of  fb. In this search, the boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association with a right-handed top quark. In the case of resonant production, for a spin- resonance with a mass of  GeV, an effective coupling strength above is excluded at 95 confidence level for the top quark and an invisible spin- state with mass between and  GeV. In the case of non-resonant production, an effective …

The European Physical Journal C

This paper presents for the first time a precise measurement of the production properties of the Z boson in the full phase space of the decay leptons. This is in contrast to the many previous precise unfolded measurements performed in the fiducial phase space of the decay leptons. The measurement is obtained from proton–proton collision data collected by the ATLAS experiment in 2012 at TeV at the LHC and corresponding to an integrated luminosity of 20.2 fb. The results, based on a total of 15.3 million Z-boson decays to electron and muon pairs, extend and improve a previous measurement of the full set of angular coefficients describing Z-boson decay. The double-differential cross-section distributions in Z-boson transverse momentum  and rapidity  are measured in the pole region, defined as GeV, over the range . The total uncertainty of the normalised cross-section measurements in the peak region of the …

The European Physical Journal C

The compatibility of W-boson mass measurements performed by the ATLAS, LHCb, CDF, and D0 experiments is studied using a coherent framework with theory uncertainty correlations. The measurements are combined using a number of recent sets of parton distribution functions (PDF), and are further combined with the average value of measurements from the Large Electron–Positron collider. The considered PDF sets generally have a low compatibility with a suite of global rapidity-sensitive Drell–Yan measurements. The most compatible set is CT18 due to its larger uncertainties. A combination of all measurements yields a value of  MeV with the CT18 set, but has a probability of compatibility of 0.5% and is therefore disfavoured. Combinations are performed removing each measurement individually, and a 91% probability of compatibility is obtained when the CDF measurement is removed. The …

The European Physical Journal C

The inclusive Higgs boson production cross-section is measured in the di-photon and the decay channels using 31.4 and 29.0 fb of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of  . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are   fb, and   fb, in agreement with the corresponding Standard Model predictions of  fb and  fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of  pb and  pb at 13.6  from the di-photon and  …

The European Physical Journal C

Measurements of the differential production cross-sections of prompt and non-prompt and mesons with transverse momenta between 8 and 360 GeV and rapidity in the range are reported. Furthermore, measurements of the non-prompt fractions of and , and the prompt and non-prompt -to- production ratios, are presented. The analysis is performed using 140 fb of  TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018.

The European Physical Journal C

A search for the production of single-top-quarks in association with missing energy is performed in proton–proton collisions at a centre-of-mass energy of with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of  fb. In this search, the boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association with a right-handed top quark. In the case of resonant production, for a spin- resonance with a mass of  GeV, an effective coupling strength above is excluded at 95 confidence level for the top quark and an invisible spin- state with mass between and  GeV. In the case of non-resonant production, an effective …

The European Physical Journal C

This paper presents for the first time a precise measurement of the production properties of the Z boson in the full phase space of the decay leptons. This is in contrast to the many previous precise unfolded measurements performed in the fiducial phase space of the decay leptons. The measurement is obtained from proton–proton collision data collected by the ATLAS experiment in 2012 at TeV at the LHC and corresponding to an integrated luminosity of 20.2 fb. The results, based on a total of 15.3 million Z-boson decays to electron and muon pairs, extend and improve a previous measurement of the full set of angular coefficients describing Z-boson decay. The double-differential cross-section distributions in Z-boson transverse momentum  and rapidity  are measured in the pole region, defined as GeV, over the range . The total uncertainty of the normalised cross-section measurements in the peak region of the …

The European Physical Journal C

We explore a novel class of Yang–Baxter deformed backgrounds (J High Energy Phys 01:056, 2021) which exhibit a non-chaotic dynamics for (super)strings propagating over it. We explicitly use the Kovacic’s algorithm in order to establish non-chaotic dynamics of string models over these deformed backgrounds. This analysis is complemented with numerical techniques whereby we probe the classical phase space of these (semi)classical strings and calculate various chaos indicators, such as, the Poincaré sections and the Lyapunov exponents. We find compatibility between the two approaches. Nevertheless, our analysis does not ensure integrability; rather, it excludes the possibility of non-integrability for the given string embeddings.

The European Physical Journal C

The inclusive Higgs boson production cross-section is measured in the di-photon and the decay channels using 31.4 and 29.0 fb of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of  . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are   fb, and   fb, in agreement with the corresponding Standard Model predictions of  fb and  fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of  pb and  pb at 13.6  from the di-photon and  …

The European Physical Journal C

Measurements of the differential production cross-sections of prompt and non-prompt and mesons with transverse momenta between 8 and 360 GeV and rapidity in the range are reported. Furthermore, measurements of the non-prompt fractions of and , and the prompt and non-prompt -to- production ratios, are presented. The analysis is performed using 140 fb of  TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018.

The European Physical Journal C

A search for the production of single-top-quarks in association with missing energy is performed in proton–proton collisions at a centre-of-mass energy of with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of  fb. In this search, the boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association with a right-handed top quark. In the case of resonant production, for a spin- resonance with a mass of  GeV, an effective coupling strength above is excluded at 95 confidence level for the top quark and an invisible spin- state with mass between and  GeV. In the case of non-resonant production, an effective …

The European Physical Journal C

This paper presents for the first time a precise measurement of the production properties of the Z boson in the full phase space of the decay leptons. This is in contrast to the many previous precise unfolded measurements performed in the fiducial phase space of the decay leptons. The measurement is obtained from proton–proton collision data collected by the ATLAS experiment in 2012 at TeV at the LHC and corresponding to an integrated luminosity of 20.2 fb. The results, based on a total of 15.3 million Z-boson decays to electron and muon pairs, extend and improve a previous measurement of the full set of angular coefficients describing Z-boson decay. The double-differential cross-section distributions in Z-boson transverse momentum  and rapidity  are measured in the pole region, defined as GeV, over the range . The total uncertainty of the normalised cross-section measurements in the peak region of the …

The European Physical Journal C

At the Large Hadron Collider (LHC), absolute luminosity calibrations obtained by the van der Meer (vdM) method are affected by the mutual electromagnetic interaction of the two beams. The colliding bunches experience relative orbit shifts, as well as optical distortions akin to the dynamic- effect, that both depend on the transverse beam separation and must therefore be corrected for when deriving the absolute luminosity scale. In the vdM regime, the beam–beam parameter is small enough that the orbit shift can be calculated analytically. The dynamic- corrections to the luminometer calibrations, however, had until the end of Run 2 been estimated in the linear approximation only. In this report, the influence of beam–beam effects on the vdM-based luminosity scale is quantified, together with the associated systematic uncertainties, by means of simulations that fully take into account the non-linearity of the beam …

The European Physical Journal C

We describe a method to generate scalar–tensor theories with Weyl symmetry, starting from arbitrary purely metric higher derivative gravity theories. The method consists in the definition of a conformally-invariant metric, that is a rank (0, 2)-tensor constructed out of the metric tensor and the scalar field. This new object has zero conformal weight and is given by, where is the conformal dimension of the scalar. As has conformal dimension of 2, the resulting tensor is trivially a conformal invariant. Then, the generated scalar–tensor theory, which we call the Weyl uplift of the original purely metric theory, is obtained by replacing the metric by in the action that defines the original theory. This prescription allowed us to define the Weyl uplift of theories with terms of higher order in the Riemannian curvature. Furthermore, the prescription for scalar–tensor theories coming from terms that have explicit …

The European Physical Journal C

We describe a method to generate scalar–tensor theories with Weyl symmetry, starting from arbitrary purely metric higher derivative gravity theories. The method consists in the definition of a conformally-invariant metric, that is a rank (0, 2)-tensor constructed out of the metric tensor and the scalar field. This new object has zero conformal weight and is given by, where is the conformal dimension of the scalar. As has conformal dimension of 2, the resulting tensor is trivially a conformal invariant. Then, the generated scalar–tensor theory, which we call the Weyl uplift of the original purely metric theory, is obtained by replacing the metric by in the action that defines the original theory. This prescription allowed us to define the Weyl uplift of theories with terms of higher order in the Riemannian curvature. Furthermore, the prescription for scalar–tensor theories coming from terms that have explicit …

The European Physical Journal C

The inclusive Higgs boson production cross-section is measured in the di-photon and the decay channels using 31.4 and 29.0 fb of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of  . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are   fb, and   fb, in agreement with the corresponding Standard Model predictions of  fb and  fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of  pb and  pb at 13.6  from the di-photon and  …

The European Physical Journal C

Measurements of the differential production cross-sections of prompt and non-prompt and mesons with transverse momenta between 8 and 360 GeV and rapidity in the range are reported. Furthermore, measurements of the non-prompt fractions of and , and the prompt and non-prompt -to- production ratios, are presented. The analysis is performed using 140 fb of  TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018.