Pion-Muon Asymmetry Revisited

Long ago an unexpected and unexplainable phenomena was observed. The distribution of muons from positive pion decay at rest was anisotropic with an excess in the backward direction relative to the direction of the proton beam from which the pions were created. Although this effect was observed by several different groups with pions produced by different means, the result was not accepted by the physics community, because it is in direct conflict with a large set of other experiments indicating that the pion is a pseudoscalar particle. It is possible to satisfy both sets of experiments if helicity-zero vector particles exist and the pion is such a particle. Helicity-zero vector particles have direction but no net spin. For the neutral pion to be a vector particle requires an additional modification to conventional theory as discussed herein. An experiment is proposed which can prove that the asymmetry in the distribution of muons from pion decay is a genuine physical effect because the asymmetry can be modified in a controllable manner. A positive result will also prove that the pion is NOT a pseudoscalar particle.Comment: 9 pages, 3 figure

The ATLAS trigger system for LHC Run 3 and trigger performance in 2022

The ATLAS trigger system is a crucial component of the ATLAS experiment at the LHC. It is responsible for selecting events in line with the ATLAS physics programme. This paper presents an overview of the changes to the trigger and data acquisition system during the second long shutdown of the LHC, and shows the performance of the trigger system and its components in the proton-proton collisions during the 2022 commissioning period as well as its expected performance in proton-proton and heavy-ion collisions for the remainder of the third LHC data-taking period (2022–2025)

Electron and photon energy calibration with the ATLAS detector using LHC Run 2 data

This paper presents the electron and photon energy calibration obtained with the ATLAS detector using 140 fb-1 of LHC proton-proton collision data recorded at √(s) = 13 TeV between 2015 and 2018. Methods for the measurement of electron and photon energies are outlined, along with the current knowledge of the passive material in front of the ATLAS electromagnetic calorimeter. The energy calibration steps are discussed in detail, with emphasis on the improvements introduced in this paper. The absolute energy scale is set using a large sample of Z-boson decays into electron-positron pairs, and its residual dependence on the electron energy is used for the first time to further constrain systematic uncertainties. The achieved calibration uncertainties are typically 0.05% for electrons from resonant Z-boson decays, 0.4% at ET ∼ 10 GeV, and 0.3% at ET ∼ 1 TeV; for photons at ET ∼ 60 GeV, they are 0.2% on average. This is more than twice as precise as the previous calibration. The new energy calibration is validated using J/ψ → ee and radiative Z-boson decays

Performance and calibration of quark/gluon-jet taggers using 140 fb−1 of pp collisions at √s = 13 TeV with the ATLAS detector

The identification of jets originating from quarks and gluons, often referred to as quark/gluon tagging, plays an important role in various analyses performed at the Large Hadron Collider, as Standard Model measurements and searches for new particles decaying to quarks often rely on suppressing a large gluon-induced background. This paper describes the measurement of the efficiencies of quark/gluon taggers developed within the ATLAS Collaboration, using √s = 13 TeV proton–proton collision data with an integrated luminosity of 140 fb-1 collected by the ATLAS experiment. Two taggers with high performances in rejecting jets from gluon over jets from quarks are studied: one tagger is based on requirements on the number of inner-detector tracks associated with the jet, and the other combines several jet substructure observables using a boosted decision tree. A method is established to determine the quark/gluon fraction in data, by using quark/gluon-enriched subsamples defined by the jet pseudorapidity. Differences in tagging efficiency between data and simulation are provided for jets with transverse momentum between 500 GeV and 2 TeV and for multiple tagger working points

Resistência de soja a insetos: IV. Comportamento de cultivares e linhagens em relação a Hedilepta indicata (Fabr.) Resistance of soybean to insects: IV. Performance of cultivars and lines in relation to Hedilepta indicata (Fabr.)

Em condições de campo e de telado, estudou-se o comportamento das seguintes linhagens e cultivares de soja em relação à lagarta-enroladeira, Hedilepta indicata (Fabr., 1775): PI 227687, IAC 73-228, IAC 79-1823, 'Santa Rosa', IAC 80-596-2, 'IAC 12', 'IAC 8', IAC 78-2318, D 72-9601-1, PI 171451, 'IAC São Carlos' e PI 229358, quanto ao número de pontos de ataque do inseto. Tanto no campo como em telado, IAC 73-228 e PI 229358 apresentaram, respectivamente, o menor e o maior valor. Em condições de campo, PI 227687 e IAC 73-228 sofreram as menores perdas de área foliar devidas ao ataque de H. indicata, enquanto 'IAC São Carlos', PI 171451 e PI 229358 se mostraram como os mais suscetíveis. Em outro experimento conduzido em campo, utilizando-se PI 274454, PI 274453, IAC 73-228, 'IAC 12', IAC 80-596-2, 'UFV-1', IAC 78-2318 e 'Paraná', os dois primeiros apresentaram alto nível de resistência ao inseto, superior ao exibido por IAC 73-228, sendo que 'Paraná' teve a maior perda de área foliar. Ainda em condições de campo, em área de seleção de plantas F2 descendentes do cruzamento de 'Paraná' com PI 274453, foram avaliadas, individualmente, plantas quanto à área foliar comida: os resultados obtidos sugerem que a resistência da PI 274453 a H. indicata seja devida a um gene dominante.<br>Performance of soybean cultivars and lines in relation to H. indicata was studied under field and screen house conditions. Differences in the number of points of attack (characterized by the rolling or junction of the folioles by means of silk secretion) were evaluated in PI 227687, IAC 73-228, IAC 79-1823, 'Santa Rosa', IAC 80-596-2, 'IAC 12', 'IAC 8', IAC 78-2318, D 72-9601-1, PI 171451, 'IAC São Carlos' and PI 229358; in both, field and screen house conditions, IAC 73-228 and PI 229358 showed, respectively, the lowest and the highest values. In the field, PI 227687 and IAC 73-228 presented low defoliation, while 'IAC São Carlos', PI 171451 and PI 229358 were highly defoliated. In another field experiment with PI 274454, PI 274453, IAC 73-228, 'IAC 12', IAC 80-596-2, 'UFV-1', IAC 78-2318 and 'Paraná', the first two varieties were highly resistant to H indicata The level of resistance of the PI's was superior to that of IAC 73-228. 'Paraná' was the most susceptible variety. Under field conditions, in an area of selection of F2 plants descendents of crosses between 'Paraná' and PI 274453, 63 plants were evaluated in relation to the eaten leaf area; the results suggest that the PI 274453 resistance to H. indicata is inherited in this cross as dominant simple, being possible to transfer it to commercial varieties