We present cross sections and angular distributions for the reaction K + d → K o pp at 865, 970, 1210, 1365 and 1585 MeV/ c . Making corrections for deuterium effects, we observe the following features of the elastic charge exchange process K + n → K 0 p: a) the c.m. angular distribution becomes increasingly peripheral as the momentum increases from 800 to 1600 MeV/ c ; b) the forward amplitude is largely real. Attempts to describe the data either in terms of a Regge model or in terms of dominance by an elastic P 1 2 isoscalar KN resonance are discussed.
No description provided.
No description provided.
No description provided.
The joint decay density-matrix elements have been measured for the ρ0Δ++ and ωΔ++ channels at 3.7 GeV/c. The data are presented as a function of momentum transfer in both the t-channel and s-channel coordinate systems. The presence of correlated decays is illustrated for both reactions by employing selective cuts on the decay angles of one resonance, and displaying the effects on the decay distribution of the opposing resonance. An amplitude analysis is performed with the data near 0° production angle, where we obtain a helicity decomposition of the scattering amplitude with no experimental ambiguity.
T-CHANNEL COORDINATE SYSTEM (XYZ=TH).
T-CHANNEL COORDINATE SYSTEM (XYZ=TH).
S-CHANNEL COORDINATE SYSTEM (XYZ=SH).
A study of the A2+ mass spectrum in π+p interactions at 3.7 GeVc is presented. For a cut of t′=0.1−2.0 GeV2 and on eliminating the Δ++ we find that the three-pion mass spectrum in the A2+ region is fitted by the dipole formula with a confidence level of 53% and a single Breit-Wigner formula with a confidence level of 11%. Our result thus favors A2+ splitting although a single Breit-Wigner fit cannot be ruled out. We also report the A2+ decay branching fractions measured over all t′ values. They are 0.78 ± 0.05, 0.15 ± 0.04, 0.06 ± 0.03, and < 0.02 for ρπ, ηπ, KK¯, and η′π, respectively, in good agreement with other experiments.
No description provided.
We present a measurement of angular observables, $P_4'$, $P_5'$, $P_6'$, $P_8'$, in the decay $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$, where $\ell^+\ell^-$ is either $e^+e^-$ or $\mu^+\mu^-$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at the $\Upsilon(4S)$ resonance with the Belle detector at the asymmetric-energy $e^+e^-$ collider KEKB. Four angular observables, $P_{4,5,6,8}'$ are extracted in five bins of the invariant mass squared of the lepton system, $q^2$. We compare our results for $P_{4,5,6,8}'$ with Standard Model predictions including the $q^2$ region in which the LHCb collaboration reported the so-called $P_5'$ anomaly.
Results of the angular analysis of $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$ (where $\ell = e,\mu$) in five bins of $q^2$, the di-lepton invariant mass squared.
$Z$ boson events at the Large Hadron Collider can be selected with high purity and are sensitive to a diverse range of QCD phenomena. As a result, these events are often used to probe the nature of the strong force, improve Monte Carlo event generators, and search for deviations from Standard Model predictions. All previous measurements of $Z$ boson production characterize the event properties using a small number of observables and present the results as differential cross sections in predetermined bins. In this analysis, a machine learning method called OmniFold is used to produce a simultaneous measurement of twenty-four $Z$+jets observables using $139$ fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=13$ TeV collected with the ATLAS detector. Unlike any previous fiducial differential cross-section measurement, this result is presented unbinned as a dataset of particle-level events, allowing for flexible re-use in a variety of contexts and for new observables to be constructed from the twenty-four measured observables.
Differential cross-section in bins of dimuon $p_\text{T}$. The actual measurement is unbinned and available with examples at <a href="https://gitlab.cern.ch/atlas-physics/public/sm-z-jets-omnifold-2024">gitlab.cern.ch/atlas-physics/public/sm-z-jets-omnifold-2024</a>
Differential cross-section in bins of dimuon rapidity. The actual measurement is unbinned and available with examples at <a href="https://gitlab.cern.ch/atlas-physics/public/sm-z-jets-omnifold-2024">gitlab.cern.ch/atlas-physics/public/sm-z-jets-omnifold-2024</a>
Differential cross-section in bins of leading muon $p_\mathrm{T]$. The actual measurement is unbinned and available with examples at <a href="https://gitlab.cern.ch/atlas-physics/public/sm-z-jets-omnifold-2024">gitlab.cern.ch/atlas-physics/public/sm-z-jets-omnifold-2024</a>
An angular analysis of the $B^{0}\rightarrow K^{*0}(\rightarrow K^{+}\pi^{-})\mu^{+}\mu^{-}$ decay is presented. The dataset corresponds to an integrated luminosity of $3.0\,{\mbox{fb}^{-1}}$ of $pp$ collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine $C\!P$-averaged observables and $C\!P$ asymmetries, taking account of possible contamination from decays with the $K^{+}\pi^{-}$ system in an S-wave configuration. The angular observables and their correlations are reported in bins of $q^2$, the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for $q^2$-dependent decay amplitudes in the region $1.1
CP-averaged angular observables evaluated by the unbinned maximum likelihood fit.
CP-averaged angular observables evaluated by the unbinned maximum likelihood fit. The first uncertainties are statistical and the second systematic.
CP-asymmetric angular observables evaluated by the unbinned maximum likelihood fit. The first uncertainties are statistical and the second systematic.
A measurement of novel event shapes quantifying the isotropy of collider events is performed in 140 fb$^{-1}$ of proton-proton collisions with $\sqrt s=13$ TeV centre-of-mass energy recorded with the ATLAS detector at CERN's Large Hadron Collider. These event shapes are defined as the Wasserstein distance between collider events and isotropic reference geometries. This distance is evaluated by solving optimal transport problems, using the 'Energy-Mover's Distance'. Isotropic references with cylindrical and circular symmetries are studied, to probe the symmetries of interest at hadron colliders. The novel event-shape observables defined in this way are infrared- and collinear-safe, have improved dynamic range and have greater sensitivity to isotropic radiation patterns than other event shapes. The measured event-shape variables are corrected for detector effects, and presented in inclusive bins of jet multiplicity and the scalar sum of the two leading jets' transverse momenta. The measured distributions are provided as inputs to future Monte Carlo tuning campaigns and other studies probing fundamental properties of QCD and the production of hadronic final states up to the TeV-scale.
IRing2 for HT2>=500 GeV, NJets>=2
IRing2 for HT2>=500 GeV, NJets>=3
IRing2 for HT2>=500 GeV, NJets>=4
This paper presents cross sections for the production of a W boson in association with jets, measured in proton--proton collisions at $\sqrt{s}=7$ TeV with the ATLAS experiment at the Large Hadron Collider. With an integrated luminosity of $4.6 fb^{-1}$, this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of 1 TeV and multiplicities up to seven associated jets. The production cross sections for W bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also presented including measurements of the jet observables such as the rapidities and the transverse momenta as well as measurements of event observables such as the scalar sums of the transverse momenta of the jets. The measurements are compared to numerous QCD predictions including next-to-leading-order perturbative calculations, resummation calculations and Monte Carlo generators.
Distribution of inclusive jet multiplicity.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the electron channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the muon channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
Event-shape observables measured using charged particles in inclusive $Z$-boson events are presented, using the electron and muon decay modes of the $Z$ bosons. The measurements are based on an integrated luminosity of $1.1 {\rm fb}^{-1}$ of proton--proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy $\sqrt{s}=7$ TeV. Charged-particle distributions, excluding the lepton--antilepton pair from the $Z$-boson decay, are measured in different ranges of transverse momentum of the $Z$ boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and $\mathcal{F}$-parameter, which are in particular sensitive to properties of the underlying event at small values of the $Z$-boson transverse momentum. The Sherpa event generator shows larger deviations from the measured observables than Pythia8 and Herwig7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high $Z$-boson transverse momenta than at low $Z$-boson transverse momenta and for the observables that are less sensitive to the number of charged particles in the event.
No description provided.
No description provided.
No description provided.
We report on a measurement of the ratio of the differential cross sections for W and Z boson production as a function of transverse momentum in proton-antiproton collisions at sqrt(s) = 1.8 TeV. This measurement uses data recorded by the D0 detector at the Fermilab Tevatron in 1994-1995. It represents the first investigation of a proposal that ratios between W and Z observables can be calculated reliably using perturbative QCD, even when the individual observables are not. Using the ratio of differential cross sections reduces both experimental and theoretical uncertainties, and can therefore provide smaller overall uncertainties in the measured mass and width of the W boson than current methods used at hadron colliders.
The measured W and Z0 cross sections used to compute the ratio.
The measured ratios of W+-/Z0 cross sections, corrected for the branching ratios BR(W-->e-nue)=0.1073+-0.0025 and BR(Z0-->E+E-)=0.033632+-0.000059 (PDG 2000). The error given is the total error, but note that the 4.3pct error in the luminosity cancels completely in the ratio.
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