Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “KAONS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

The differential production cross section of the ϕ (1020) meson in s = 7 TeV p p collisions measured with the ATLAS detector

CERN-LHC. A measurement is presented of the PHI --> K+ K- production cross section at sqrt(s) = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 mub^{-1}, collected with the ATLAS experiment at the LHC in April 2010. Selection of PHI(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, PT(PHI), and rapidity, ABS(YRAP(PHI)), of the phi(1020) meson in the fiducial region 500 < PT(PHI) < 1200 MeV, ABS(YRAP(PHI)) < 0.8, kaon transverse momentum PT(K) > 230 MeV and kaon momentum P(K) < 800 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Observation of Muon Neutrino Charged Current Events in an Off-Axis Horn-Focused Neutrino Beam Using the NOvA Prototype Detector

The NOνA is a long base-line neutrino oscillation experiment. It will study the oscillations between muon and electron neutrinos through the Earth. NOνA consists of two detectors separated by 810 km. Each detector will measure the electron neutrino content of the neutrino (NuMI) beam. Differences between the measurements will reveal details about the oscillation channel. The NOνA collaboration built a prototype detector on the surface at Fermilab in order to develop calibration, simulation, and reconstruction tools, using real data. This 220 ton detector is 110 mrad off the NuMI beam axis. This off-axis location allows the observation of neutrino interactions with energies around 2 GeV, where neutrinos come predominantly from charged kaon decays. During the period between October 2011 and April 2012, the prototype detector collected neutrino data from 1.67 × 10 20 protons on target delivered by the NuMI beam. This analysis selected a number of candidate charged current muon neutrino events from the prototype data, which is 30% lower than predicted by the NOνA Monte Carlo simulation. The analysis suggests that the discrepancy comes from an over estimation of the neutrino flux in the Monte Carlo simulation, and in particular, from neutrinos generated in charged kaon decays. The ratio of measured divided by the simulated flux of muon neutrinos coming from charged kaon decays is: 0.70 +0.108 -0.094 . The NOνA collaboration may use the findings of this analysis to introduce a more accurate prediction of the neutrino flux produced by the NuMI beam in future Monte Carlo simulations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Measurement of Single Spin Asymmetry in 3 He↑(e, e'K ± )X from a Transversely Polarized 3 He Target

Spin-dependent observables are a powerful tool to probe the internal structure of the nucleon and to study the dynamics of the strong interaction. Experimental study of the nucleon spin structure has provided us with many exciting and often surprising results. The so-called "spin crisis" in the 1980s revealed the limitation of naive quark-parton models and led to a worldwide effort to study the nucleon spin structure. However, this effort has been focused mainly on the nucleon's longitudinal spin structure. Recently, when the pioneer work revealed the significant role that transverse spin plays in understanding the full structure of the nucleon and in understanding the dynamics of the strong interaction, the study of the transverse spin structure became the new focus of the worldwide effort. Jefferson Lab (JLab) is located at Newport News, VA, US. It is equipped with the continuous electron beam accelerator facility (CEBAF) and four experimental halls: A, B, C and D. The accelerator can provide a continuous electron beam (2 ns beam bunch) with high polarization (up to ~ 90%) and high current (up to ~ 200μA) for fixed target experiments in all experimental halls. Hall A consists of two standard high-resolution spectrometers (HRS): left HRS (LHRS) and right HRS (RHRS). Another spectrometer, the BigBite spectrometer, can be installed on request by certain experiments. The experiment E06-010 ("Transversity Experiment") at JLab Hall A is the first measurement of the transverse spin structure of the neutron using a transversely polarized 3 He target and a 5.89 GeV incident electron beam. The experiment measured target single spin asymmetries (SSA) and beam-target double-pin asymmetries (DSA) in semi-inclusive deep-inelastic scattering (SIDIS) and in deep-inelastic scattering (DIS) processes. It also collected inclusive hadron (pion, kaon and proton) production data parasitically. The scattered electrons were detected in the BigBite spectrometer with associated detectors while the hadrons were detected with the LHRS which had excellent particle identification capabilities. In this dissertation, the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized 3 He target will be discussed. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematical range of 0.1 bj <0.4 for K + and K - production. While the Collins and Sivers moments for K+ are consistent with zero within the experimental uncertainties, both moments for K- favor negative values. The Sivers moments are compared to the theoretical prediction from a phenomenological fit to the world data. While the K + Sivers moments are consistent with the prediction, the K - results differ from the prediction at the 2-sigma level. The measurements of SSA and DSA in the inclusive hadron (pion, kaon, proton) production channels, with an average transverse momentum T >=0.64 GeV/c, will also be discussed. The asymmetries strongly depend on the flavor of hadron. The π + and π - asymmetries are opposite in sign, demonstrated a strong flavor dependency similar to what has been observed in polarized p ↑ +p collisions. These measurements have provided important inputs to the world's data set on the investigation of transverse spin structure of the nucleon. They also laid the foundation for the future high precision study of the subject in the 12-GeV JLab and a future electron-ion collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

The Halls B and C semi-inclusive deep inelastic scattering program towards the transverse momentum dependence of valence quarks

Inclusive and semi-inclusive deep inelastic scattering (DIS and SIDIS) are important tools for understanding the structure of nucleons and nuclei. Spin asymmetries in polarized SIDIS are directly related to transverse momentum dependent parton distributions (TMDs) and fragmentation functions. The usual collinear parton distribution functions depend on the fraction of hadron momentum carried by the parton, x, and the space-time resolution scale, Q2. The TMDs, which depend also on the intrinsic transverse momentum of the parton, kT, provide a three-dimensional partonic picture of the nucleon in momentum space. These TMDs have not yet been studied in detail. The 12 GeV era at JLab can move this to a new level of sophistication, thanks to the extraordinary statistical accuracy achievable and the extended kinematic reach provided by the 11 GeV beam. This calls for a multi-pronged approach with multi-dimensional data, for all combinations of beam and target polarization, and different hadrons. Hall B with its large-acceptance CLAS12 spectrometer will likely be the workhorse of SIDIS physics to provide multi-dimensional cross sections, azimuthal distributions and single- and double-spin asymmetries, using both unpolarized and polarized proton and deuteron targets, and unpolarized nuclear targets. The much-anticipated addition of a RICH detector to the CLAS12 base equipment will start an unprecedented SIDIS program with kaons, giving insights to the strange flavor dependence of the TMDs. Hall C with its "pinhole" magnetic spectrometer pair would add precision cross sections and their ratios for both pions and kaons. The rigid connection to the pivot allows for longitudinal-transverse separations, unique amongst the Hall experimental setups. Given the relative simplicity to change the magnet polarities, and the anticipated large reproducibility and systematic understanding of the spectrometer setup, Hall C will be the best place for 1%-level measurements of ?+/?? ratios, or kaon ratios, and due to its precision will allow for longitudinal-transverse separations, unique amongst the Hall experimental setups. Disadvantage of the setup is the lack of full azimuthal coverage at larger pT. The multi-pronged SIDIS approach combining foreseen 12-GeV experiments in large acceptance Hall B and precision Hall C will be presented.

Ent, Rolf↗
DOE OSTI2023

Status of Measuring Cross Sections of Hadrons on Argon with ProtoDUNE-SP

ProtoDUNE Single-Phase is a 700-ton liquid argon detector operated in the CERN Neutrino Platform from 2018 to 2020. It is part of the Deep Underground Neutrino Experiment (DUNE), a long-baseline neutrino oscillation experiment with a 40 kT liquid argon far detector to be built at the Sanford Underground Research Facility and a near detector, with both argon and non-argon detector technologies, to be hosted at the Fermi National Accelerator Laboratory. A critical uncertainty to understand in the neutrino oscillation program of DUNE is the uncertainty on final state interactions, either reaction or elastic, of various hadrons on argon since the scattering of neutrino-induced hadrons off argon bias the hadron's measured energy. It can also prevent algorithms from identifying the hadron's particle type. Protons, kaons, and pions from the beam are especially important for the DUNE neutrino program as they represent common final state particles in neutrino interactions off a nucl eus. Therefore, ProtoDUNE is analyzing the test beam data to measure cross sections of pions, protons, and kaons on argon, aiming to tune parameters that model charged particle scattering off argon. This talk will discuss the data-taking program for ProtoDUNE and an overview of the status and results of measuring cross sections of pions, protons, and kaons on argon. It will conclude with a brief overview of how these measurements can be used for future liquid argon neutrino detectors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Three-pion effects in $K^0-\bar{K}^0$ mixing

The rate of mixing between a neutral kaon and an anti-kaon ($K^0$-$\bar{K}^0$) is given, in part, by a long-range matrix element, defined with two insertions of the weak Hamiltonian separated by physical, Minkowski time evolution. For physical quark masses, the kaon mass lies above the two- and three-pion thresholds and, as a result, this long-range matrix element receives contributions from intermediate on-shell $2\pi$ and $3\pi$ states. These contributions cannot easily be captured in a finite Euclidean spacetime, meaning that such matrix elements are not directly accessible via lattice QCD. In this talk, we present a strategy for combining quantities that can be extracted in numerical lattice QCD calculations in order to reproduce the physical, infinite-volume long-range amplitude for $K^0-\bar{K}^0$. The key novelty relative to published work is that we fully include the effects of three-particle states that were previously neglected. The strategy is built on existing formalism for long-range matrix elements with two-particle intermediate states, together with the relativistic-field-theory finite-volume formalism for extracting three-hadron weak decays.

Jackura, Andrew↗
DOE OSTI2016

Preface and Summary

Primary Physics with Secondary Beams of K L 's Not all of physics can be explored by primary beams of electrons and protons, however much these have taught us over the past 60 years. Electron-positron colliders give access to restricted sets of quantum numbers. From proton-proton collisions we have long learned about all manner of high energy reactions. However, access to excited mesons and baryons has been most universally achieved with pion and kaon secondary beams, and latterly pho-ton beams both virtual and real. Nowadays the wealth of information on polarized photon beams on polarized targets has totally revolutionized baryon spectroscopy, especially in the lightest flavor sector. The measurement of polarization asymmetries has constrained partial wave analyses far beyond anything conceivable with pion beams. Nevertheless, these only give access to the product of photocouplings of each excited baryon and its coupling to the hadron final state, such as πN , ππN , ηN , etc. Contemporaneously, in the meson sector, the COMPASS experiment with pion beams on protons at 190 GeV/c, together with heavy flavor decays in e + e - annihilation, have given access to multi-meson final states, like 2π, 3π, with greater precision than ever before. This has given hints and suggestions of new resonances, like the a 1 (1420). To understand the constituent structure of hadrons requires information on the relationship of each meson and baryon to those with different flavors, but the same J P quantum numbers. At its simplest, this is to understand the quark model multiplet structure, where this is appropriate. What is more, so ubiquitous are ππ, πK, KK, ηπ, ηK, ... final states as the decay products of almost every hadron, that knowledge of the properties of these is critical to every analysis. Unitarity colors and shapes the universality of such final state interactions in each set of quantum numbers. This means that however precise our measurements of γN → πη () N , with GlueX for instance, we cannot really determine the fine resonant structure of such a process without some information on πη and πη scattering too. Nor can we determine any flavor partners without information on the corresponding Kη () channels. For that secondary kaon beams are essential. While J-PARC has a whole program of charged strange particle and hypernuclear reactions, photon beams allow unique access to other channels. It was realized long ago that intense photon beams like that about to be delivered to Hall D at JLab, could produce secondary beams. The charged particles can readily be bent away, leaving a neutral particle beam dominated by K L : long lived kaons being produced far more copiously than neutrons above 3–4 GeV momentum. Such a facility provides access to a whole range of physics that is the subject of this meeting. The reactions that can be studied cover the meson spectrum and dynamics, the baryon spectrum and dynamics, and final state interactions that link mesons and baryons together. This includes particularly the channels Kπ, Kη, Kη in the meson sector. These explore the very limitations of chiral dynamics: the strange quark's current mass is 30-50 times that of the

42 ENGINEERING↗
DOE OSTI2024

Novel Instrumentation for Advanced Quantum Chromodynamics Studies with Flavor Sensitivity

The true nature of ordinary matter has always fascinated humankind, whose imagination has been pointed to the right direction since the 5th century BC with the first known atomic theory by Leucippus and Democritus. They described the matter as formed by small, invisible, indivisible, and eternal particles: the atoms. A long investigation followed them, including contributions from several of history?s greatest philosophers and scientists. The progress led to the understanding that atoms have an internal structure consisting of a central nucleus composed of protons and neutrons, surrounded by a cloud of electrons. About 50 years ago, scientists discovered that nucleons also have an internal structure. Through the Deep Inelastic Scattering (DIS) experiments, on which a lepton is scattered off a nucleon, it was possible to access the distribution of partons inside the nucleon along the longitudinal direction defined by the hard-scale probe. It was a crucial step in developing Quantum Chromodynamics (QCD), currently the best theory describing the subatomic matter. Ultimately, DIS was recognized as a limited tool to investigate the nucleon structure because it is mainly sensitive to observables at the probe?s energy scale. In recent decades, theoretical developments have allowed defining soft-scale observables by measuring more complex processes. Reactions such as Semi-Inclusive Deep Inelastic Scattering (SIDIS) with single or di-hadron production, can provide information about the momentum of parton inside the nucleon. In particular, polarized SIDIS allows access to the Transverse-Momentum-Dependent (TMD) parton distributions describing the correlations of the quark and gluon degrees of freedom in transverse momentum and spin. This study can provide three-dimensional imaging of nucleon structure and inner dynamics, as long as the hadronic component in the final state can be measured. Identifying the species of the produced particles provides information on the quark flavor and assumes a crucial role in this context. The thesis describes the work carried out by the author in preparing novel instrumentation for particle identification in the final state of DIS experiments, to support modern analysis of the parton dynamics within the basic confined object (nucleon) with flavor sensitivity. The work has been focused on the CLAS12 spectrometer in operation at Jefferson Laboratory (JLab), Newport News, VA, USA, and the ePIC experiment in preparation for the future Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL), Long Island, NY, USA. CLAS12 is a fixed-target experiment using a 12 GeV beam of polarized electrons scattering off polarized nuclear targets. In 2018 and 2022, two Ring Imaging Cherenkov (RICH) detector modules were installed to improve the ?±/K± separation in the high-momentum region (3÷8 GeV/c) of the experiment. The author contributed to the assembly, installation, and com- missioning of the second RICH module, to the efficiency studies of the first module, and to the first SIDIS analysis with high-momentum kaons identified by the RICH. These studies led to the observation of the first spin asymmetry with high-momentum kaons from the CLAS12 experiment, and an initial assessment of the systematic error associated with the hadron identification. ePIC will be the first experiment at the future EIC, the new collider designed to expand the frontiers of QCD. The author was involved in the development of the dual-radiator Ring Imaging Cherenkov (dRICH). This detector will interpolate the measurements of the Cherenkov angles of photons produced by relativistic particles crossing two different radiators to identify charged hadrons. The author contributed to the studies conducted with the dRICH prototype, developing the reconstruction and analysis software and simulations, characterizing the aerogel radiator samples, and being responsible for the tracking system used during the beam tests. The performance obtained by the prototype has been progressively improved and the results are now comparable with the expectation derived from the simulation and satisfy the requirements of the experiment. In Chapter 1, the SIDIS theory is briefly introduced, outlying the connection with the experimental measurement. Chapter 2 includes the description of the CLAS12 RICH, its assembly and installation, and the efficiency study. In Chapter 3, the analysis of the Beam-Spin Asymmetry associated with SIDIS kaons is described. Chapter 4 describes the contribution to the dRICH for EIC, starting from a description of the ePIC experiment and focusing on the studies performed for the dRICH prototype. The conclusions of this work are summarized at the end.

Vallarino, Simone↗
DOE OSTI2011

Analyzing Unfavored Fragmentation Functions Using NJL-Jet Model

The Nambu-Jona-Lasinio (NJL)-jet model provides a sound framework for calculating the fragmentation functions in an effective chiral quark theory, where the momentum and isospin sum rules are satisfied without the introduction of ad hoc parameters. The most recent version of the model includes the fragmentation of the light and strange quarks to pions, kaons, nucleons, and antinucleons; where the effects of the production of secondary pions and kaons from the vector mesons {rho}, K* and {phi} are also calculated. The results for the model fragmentation function exhibit a qualitative agreement with the empirical parameterizations. The results also allow to test, within the model assumptions, several assumption in parametrizations of the unfavored fragmentation functions used in empirical fits to the experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Dark matter searches for monoenergetic neutrinos arising from stopped meson decay in the Sun

Dark matter can be gravitationally captured by the Sun after scattering off solar nuclei. Annihilations of the dark matter trapped and accumulated in the centre of the Sun could result in one of the most detectable and recognizable signals for dark matter. Searches for high-energy neutrinos produced in the decay of annihilation products have yielded extremely competitive constraints on the spin-dependent scattering cross sections of dark matter with nuclei. Recently, the low energy neutrino signal arising from dark-matter annihilation to quarks which then hadronize and shower has been suggested as a competitive and complementary search strategy. These high-multiplicity hadronic showers give rise to a large amount of pions which will come to rest in the Sun and decay, leading to a unique sub-GeV neutrino signal. We here improve on previous works by considering the monoenergetic neutrino signal arising from both pion and kaon decay. We consider searches at liquid scintillation, liquid argon, and water Cherenkov detectors and find very competitive sensitivities for few-GeV dark matter masses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Balance functions of (un)identified hadrons in Pb–Pb, p–Pb, and pp collisions at the LHC

In ultrarelativistic heavy-ion collisions, correlations of particles with opposite quantum numbers provide insight into quark production mechanisms and time scales, collective motion, and re-scattering in the hadronic phase. The longitudinal and azimuthal widths of balance functions for charged kaons and charged pions are used to examine the two-wave quark production model proposed to explain quark-antiquark production within the QGP, which predicts a large increase in up and down quark pairs relative to strange quark pairs around the time of hadronization. Balance functions are also analyzed in small collision systems such as p–Pb and pp to study fragmentation effects and possible collective effects in high-multiplicity events. A comprehensive set of balance functions has been measured using the ALICE detector, including results for unidentified hadrons in Pb–Pb and p–Pb collisions at √ s NN = 5.02 TeV, for charged pions in Pb–Pb collisions at √ s NN = 2.76 TeV, p–Pb collisions at √ s NN = 5.02 TeV and pp collisions at √ s NN = 7 TeV, and for charged kaons in Pb–Pb collisions at √ s NN = 2.76 TeV. The first balance function yield results are also presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Strange particle production at low and intermediate energies

The weak kaon production off the nucleon induced by neutrinos and antineutrinos is studied at low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments. We develop a microscopical model based on the SU(3) chiral Lagrangians. The studied mechanisms are the main source of kaon production for neutrino energies up to 2 GeV for the various channels and the cross sections are large enough to be amenable to be measured by experiments such as Minerva, T2K and NOvA.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measurement of the induced Lambda^0(1116) polarization in K^+ electroproduction at CLAS

We are using the p(e,e'K{sup +}p){pi}{sup -} reaction to perform a measurement of the induced polarization of the electroproduced L(1116) using its p{pi}{sup -} parity-violating weak decay. This study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton over the kinematics 0.8 {le} Q{sup 2} {le} 3.5 GeV{sup 2}, 1.6 {le} W {le} 3.0 GeV, and the full kaon CM angle range. In this experiment a 5.5 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for models of the electromagnetic production of K-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, LEPS, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances. Preliminary polarization results will be presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Weak production of strange particles off the nucleon

The strange particle production off the nucleon induced by neutrinos and antineutrinos is investigated at low and intermediate energies. We develop a microscopic model based on the SU(3) chiral Lagrangian. The studied mechanisms are the main source of single kaon production for (anti)neutrino energies up to 1.5 GeV. Using this model we have also studied the associated production of kaons and hyperons. The cross sections are large enough to be measured by experiments such as MINERνA, T2K and NOνA.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Simulation of atmospheric temperature effects on cosmic ray muon flux

The collision between a cosmic ray and an atmosphere nucleus produces a set of secondary particles, which will decay or interact with other atmosphere elements. This set of events produced a primary particle is known as an extensive air shower (EAS) and is composed by a muonic, a hadronic and an electromagnetic component. The muonic flux, produced mainly by pions and kaons decays, has a dependency with the atmosphere’s effective temperature: an increase in the effective temperature results in a lower density profile, which decreases the probability of pions and kaons to interact with the atmosphere and, consequently, resulting in a major number of meson decays. Such correlation between the muon flux and the atmosphere’s effective temperature was measured by a set of experiments, such as AMANDA, Borexino, MACRO and MINOS. This phenomena can be investigated by simulating the final muon flux produced by two different parameterizations of the isothermal atmospheric model in CORSIKA, where each parameterization is described by a depth function which can be related to the muon flux in the same way that the muon flux is related to the temperature. This research checks the agreement among different high energy hadronic interactions models and the physical expected behavior of the atmosphere temperature effect by analyzing a set of variables, such as the height of the primary interaction and the difference in the muon flux.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Monoenergetic neutrinos from dark matter annihilation: Issues of exposure

We consider searches for dark matter annihilation in the Sun resulting in monoenergetic neutrinos, produced either directly or through the decay of stopped pions and kaons. We find that this strategy is very successful at increasing the signal-to-background ratio, but that current experiments may be signal limited. We discuss the exposures need to fully exploit this search strategy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Directional searches at DUNE for sub-GeV monoenergetic neutrinos arising from dark matter annihilation in the Sun

Here, we consider the use of directionality in the search for monoenergetic sub-GeV neutrinos arising from the decay of stopped kaons, which can be produced by dark matter annihilation in the core of the Sun. When these neutrinos undergo charged-current interactions with a nucleus at a neutrino detector, they often eject a proton which is highly peaked in the forward direction. The direction of this track can be measured at DUNE, allowing one to distinguish signal from background by comparing on-source and off-source event rates. We discover that directional information can enhance the signal to background ratio by up to a factor of 5.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Search for the production of Higgs-portal scalar bosons in the NuMI beam using the MicroBooNE detector

We present the strongest experimental limits to date on the mixing angle, 𝜃, with which a new scalar particle, 𝑆, mixes with the Higgs field in the mass range 110 MeV < 𝑚 𝑆 <155 MeV. This result uses the MicroBooNE liquid argon time projection chamber to search for decays of these Higgs-portal scalar particles through the 𝑆 → 𝑒 + ⁢𝑒 − channel with the decays of kaons in the NuMI neutrino beam acting as the source of the scalar particles. The analysis uses an exposure of 2.01 × 10 21 protons on target of NuMI beam data including periods when the beam focusing system was configured to focus positively charged hadrons and separate periods when negatively charged hadrons were focused. The analysis searches for scalar particles produced from kaons decaying in flight in the beam’s decay volume and at rest in the target and absorber. At 𝑚 𝑆 =125 MeV (𝑚 𝑆 =150 MeV) we set a limit of 𝜃 < 3.19 ×10 −4 (𝜃 < 2.79 ×10 −4 ) at the 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗