What Is at Play? Meta-techniques in Serious Games and Their Effects on Social Believability and Learning

We discuss several examples of meta-techniques, used in Live Action Role Play to communicate information outside the story world, and suggest that they may be used to make non-player characters more socially believable by providing players with insight into what is at play in characters’ minds. We discuss how the use of these techniques could influence player immersion and how this may impact the learning effects of serious games

'VOR' - an interactive iPad model of the combined angular and linear vestibulo-ocular reflex

The mammalian vestibular system consists of a series of sensory organs located in the labyrinths of the inner ear that are sensitive to angular and linear movements of the head. Afferent inputs from the vestibular end organs contribute to balance, proprioception and vision. The vestibulo-ocular reflex (VOR) driven by these sensory inputs produces oculomotor responses in a direction opposite to head movement which tend to stabilise visual images on the retina. We present a model, in the form of a software application called VOR, which represents a simplified view of this complex system. The basis for our model is the hypothesis that afferent vestibular signals are integrated to maintain a notional internal representation of the head position (RHP). The vestibulo-ocular reflex maintains gaze towards a world-fixed point relative to the RHP, regardless of the actual head position. The RHP will imperfectly match the real head position when end organ input imperfectly reports head movements, such as can occur in cases of organ dysfunction and even in healthy subjects due to adaptation to motion stimuli. We do not claim that any specific observable part of the real vestibulo-ocular system corresponds to the RHP, but it seems reasonable to suggest that it might exist as a literal "neural network", trained through evolution and experience to maintain gaze during head movement. We hypothesise that the real VOR is supported by this internal representation, continually updated by afferent signals from the vestibular end organs, and that VOR eye responses tend to direct the eyes towards a fixed point in the world. Human vestibulo-ocular research typically employs equipment to which a subject is securely attached and allows rotation around, and sometimes linear movement along, one or more axes ("rotating chair") while attempting to maintain gaze on a fixation point, fixed relative to the head or world. A series of consecutive movements are referred to as a "motion profile". Meanwhile eye movements are recorded, using scleral search coils (or, more recently, video cameras and image-processing software) which can detect the horizontal, vertical and torsional components of the direction of each eye. VOR allows the user to define motion profiles and predicts the eye movements that a researcher or clinician might expect to observe in a real subject during such motion profiles. For example, the "on-centre rotation" motion profile specifies that the subject's head is positioned upright and centred around the vertical axis of the rotating chair, with a chair-fixed fixation point 1m in front of the subject. The chair accelerates angularly to 200°/sec over 20 seconds, rotates at a constant 200°/sec for 60 seconds, then decelerates to stationary over 20 seconds. The model accurately predicts the transient nystagmus that would be expected: its direction, duration, phase velocity and even the brief secondary nystagmus which is characteristic of adaptation to constant velocity rotation. VOR also allows the user to define end organ condition configurations, e.g. "normal", "bilateral vestibular loss", "unilateral superior neuritis", which are represented as a series of response gains attached to the sensory inputs from each end organ, relative to a nominal perfect gain of 1, and various other parameters which are derived from the human vestibular system, including the rate of drift of gaze to fixation point in light and dark, the rate at which the end organs adapt to constant stimuli, and quick-phase trigger dependencies. The VOR is not the only source of eye movement while attempting to maintain gaze on a fixation point. In our model, eye position drifts towards the fixation point at a nominal fixed rate. If this slow drift is insufficient to maintain gaze on the fixation point, a saccade or quick phase is triggered. Hence the transduction of mechanical forces at the labyrinths into sensory signals, subject to end organ conditions and adaptation that reduce the strength of the neuronal signals, maintain the RHP. Eye movement is then determined entirely by (a) the direction from RHP to the (world-referenced) fixation point, and (b) the disparity between eye direction and actual fixation point (which may be head-referenced). To validate the model, we prepared 24 motion profile/end organ condition combinations, compared the outputs from our model with real world observations, and found the results to be similar. Similarities include a simple first approximation of the linear and angular VOR; nystagmus caused by a subject's attempts to maintain fixation on a head-referenced target during head movement; decay of nystagmus through adaptation to stimulus, including secondary nystagmus; indefinitely prolonged nystagmus during off-vertical axis rotation (OVAR); rapid decay of nystagmus during the "tilt dump" motion profile, and dynamic cyclovergence during vertical linear acceleration. VOR is programmed in Objective-C using Xcode and runs on the Apple iPad. Its screen displays a 3d graphical representation of the virtual subject's head and eyes, including imaginary lines of sight to clarify eye movements. The user may program an effectively unlimited series of linear and angular motions of the rotating chair, and of the virtual subject's head relative to the chair. They may also program the gain (roughly, the sensitivity) associated with each end organ and other variables relating to the subject. They may select a series of internal variables to chart during the motion profile such as head velocity, eye direction, neuron firing rates, etc., while simultaneously displaying the head and eyes. VOR can record a video screen capture of the virtual head, eyes and lines of sight during the execution of a motion profile, a CSV file containing the internal variables at each time interval, a PNG image of the labelled chart, PDF descriptions of the motion profile and end organ condition configurations, and data files defining the motion profiles and end organ conditions which can then be exchanged between researchers/clinicians. Predefined motion profiles include: lateral, LARP and RALP head impulses; lateral head impulse with close fixation point; sinusoidal yaw, on-centre rotation, linear heave along Y axis, linear oscillation along X, Y and Z axes; linear sled along Y axis; forward- and backward-facing centrifugation; off-vertical axis rotation; tilt dump; and head tilt. Predefined conditions include: normal; left unilateral vestibular loss; bilateral vestibular loss; left superior neuritis; and "perfect" (unrealistic gain of 1 in otoliths, producing perfect linear VOR). All of these motion profiles and conditions may easily be modified, created and shared

Combination of searches for heavy spin-1 resonances using 139 fb−1 of proton-proton collision data at √s = 13 TeV with the ATLAS detector

A combination of searches for new heavy spin-1 resonances decaying into diferent pairings of W, Z, or Higgs bosons, as well as directly into leptons or quarks, is presented. The data sample used corresponds to 139 fb−1 of proton-proton collisions at √s = 13 TeV collected during 2015–2018 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting quark pairs (qq, bb, tt¯, and tb) or third-generation leptons (τν and τ τ ) are included in this kind of combination for the frst time. A simplifed model predicting a spin-1 heavy vector-boson triplet is used. Cross-section limits are set at the 95% confdence level and are compared with predictions for the benchmark model. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The complementarity of the various analyses increases the sensitivity to new physics, and the resulting constraints are stronger than those from any individual analysis considered. The data exclude a heavy vector-boson triplet with mass below 5.8 TeV in a weakly coupled scenario, below 4.4 TeV in a strongly coupled scenario, and up to 1.5 TeV in the case of production via vector-boson fusion

Search for the Zγ decay mode of new high-mass resonances in pp collisions at √s = 13 TeV with the ATLAS detector

This letter presents a search for narrow, high-mass resonances in the Zγ final state with the Z boson decaying into a pair of electrons or muons. The √s = 13 TeV pp collision data were recorded by the ATLAS detector at the CERN Large Hadron Collider and have an integrated luminosity of 140 fb−1. The data are found to be in agreement with the Standard Model background expectation. Upper limits are set on the resonance production cross section times the decay branching ratio into Zγ. For spin-0 resonances produced via gluon–gluon fusion, the observed limits at 95% confidence level vary between 65.5 fb and 0.6 fb, while for spin-2 resonances produced via gluon–gluon fusion (or quark–antiquark initial states) limits vary between 77.4 (76.1) fb and 0.6 (0.5) fb, for the mass range from 220 GeV to 3400 GeV

Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector

A search for a new heavy scalar particle X decaying into a Standard Model (SM) Higgs boson and a new singlet scalar particle S is presented. The search uses a proton-proton (pp) collision data sample with an integrated luminosity of 140 fb−1 recorded at a centre-of-mass energy of s√ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The most sensitive mass parameter space is explored in X mass ranging from 500 to 1500 GeV, with the corresponding S mass in the range 200–500 GeV. The search selects events with two hadronically decaying τ-lepton candidates from H → τ+τ− decays and one or two light leptons (ℓ = e, μ) from S → VV (V = W, Z) decays while the remaining V boson decays hadronically or to neutrinos. A multivariate discriminant based on event kinematics is used to separate the signal from the background. No excess is observed beyond the expected SM background and 95% confidence level upper limits between 72 fb and 542 fb are derived on the cross-section σ(pp → X → SH) assuming the same SM-Higgs boson-like decay branching ratios for the S → VV decay. Upper limits on the visible cross-sections σ(pp → X → SH → WWττ) and σ(pp → X → SH → ZZττ) are also set in the ranges 3–26 fb and 6–33 fb, respectively

Measurement of the cross-sections of the electroweak and total production of a Zγ pair in association with two jets in pp collisions at √s = 13 TeV with the ATLAS detector

This Letter presents the measurement of the fiducial and differential cross-sections of the electroweak production of a Zγ pair in association with two jets. The analysis uses 140 fb−1 of LHC proton–proton collision data taken at √s = 13 TeV recorded by the ATLAS detector during the years 2015–2018. Events with a Z boson candidate decaying into either an e+e− or μ+μ− pair, a photon and two jets are selected. The electroweak component is extracted by requiring a large dijet invariant mass and by using the information about the centrality of the system and is measured with an observed and expected significance well above five standard deviations. The fiducial pp → Zγ jj cross-section for the electroweak production is measured to be 3.6 ± 0.5 fb. The total fiducial cross-section that also includes contributions where the jets arise from strong interactions is measured to be 16.8+2.0 −1.8 fb. The results are consistent with the Standard Model predictions. Differential cross-sections are also measured using the same events and are compared with parton-shower Monte Carlo simulations. Good agreement is observed between data and predictions

Software performance of the ATLAS track reconstruction for LHC run 3

Charged particle reconstruction in the presence of many simultaneous proton–proton (pp) collisions in the LHC is a challenging task for the ATLAS experiment’s reconstruction software due to the combinatorial complexity. This paper describes the major changes made to adapt the software to reconstruct high-activity collisions with an average of 50 or more simultaneous pp interactions per bunch crossing (pileup) promptly using the available computing resources. The performance of the key components of the track reconstruction chain and its dependence on pile-up are evaluated, and the improvement achieved compared to the previous software version is quantified. For events with an average of 60 pp collisions per bunch crossing, the updated track reconstruction is twice as fast as the previous version, without significant reduction in reconstruction efficiency and while reducing the rate of combinatorial fake tracks by more than a factor two

Search for heavy Higgs bosons with flavour-violating couplings in multi-lepton plus b-jets final states in pp collisions at 13 TeV with the ATLAS detector

A search for new heavy scalars with flavour-violating decays in final states with multiple leptons and b-tagged jets is presented. The results are interpreted in terms of a general two-Higgs-doublet model involving an additional scalar with couplings to the top-quark and the three up-type quarks (ρtt, ρtc, and ρtu). The targeted signals lead to final states with either a same-sign top-quark pair, three top-quarks, or four top-quarks. The search is based on a data sample of proton-proton collisions at √s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. Events are categorised depending on the multiplicity of light charged leptons (electrons or muons), total lepton charge, and a deep-neural-network output to enhance the purity of each of the signals. Masses of an additional scalar boson mH between 200 − 630 GeV with couplings ρtt = 0.4, ρtc = 0.2, and ρtu = 0.2 are excluded at 95% confidence level. Additional interpretations are provided in models of R-parity violating supersymmetry, motivated by the recent flavour and (g − 2)μ anomalies

Search for lepton-favour violation in high-mass dilepton final states using 139 fb−1 of pp collisions at √s = 13 TeV with the ATLAS detector

A search is performed for a heavy particle decaying into different-flavour, dilepton final states, using 139 fb−1 of proton-proton collision data at √s = 13 TeV collected in 2015–2018 by the ATLAS detector at the Large Hadron Collider. Final states with electrons, muons and hadronically decaying tau leptons are considered (eμ, eτ or μτ). No significant excess over the Standard Model predictions is observed. Upper limits on the production cross-section are set as a function of the mass of a Z′ boson, a supersymmetric τ-sneutrino, and a quantum black-hole. The observed 95% CL lower mass limits obtained on a typical benchmark model Z′ boson are 5.0 TeV (eμ), 4.0 TeV (eτ), and 3.9 TeV (μτ), respectively

Search for non-resonant production of semi-visible jets using Run 2 data in ATLAS

Semi-visible jets, with a significant contribution to the event's missing transverse momentum, can arise in strongly interacting dark sectors. This results in an event topology where one of the jets can be aligned with the direction of the missing transverse momentum. The first search for semi-visible jets produced via a t-channel mediator exchange is presented. The analysis uses proton-proton collisions with an integrated luminosity of 139 fb−1 and a centre-of-mass energy of 13 TeV, collected with the ATLAS detector during the Run 2 of the LHC. No excess over Standard Model predictions is observed. Assuming a coupling strength of unity between the mediator, a Standard Model quark and a dark quark, mediator masses up to 2.7 TeV are excluded at the 95% confidence level. Upper limits on the coupling strength are also derived