Kinematic Events Research Articles

Detection prospects of light NMSSM Higgs pseudoscalar via cascades of heavier scalars from vector boson fusion and Higgs-strahlung

A detection at the large hadron collider of a light Higgs pseudoscalar would, if interpreted in a supersymmetric framework, be a smoking gun signature of non-minimal supersymmetry. In this work in the framework of the next-to-minimal supersymmetric standard model we focus on vector boson fusion and Higgs-strahlung production of heavier scalars that subsequently decay into pairs of light pseudoscalars. We demonstrate that although these channels have in general very limited reach, they are viable for the detection of light pseudoscalars in some parts of parameter space and can serve as an important complementary probe to the dominant gluon-fusion production mode. We also demonstrate that in a Higgs factory these channels may reach sensitivities comparable to or even exceeding the gluon fusion channels at the Large Hadron Collider, thus possibly rendering this our best option to discover a light pseudoscalar. It is also worth mentioning that for the singlet dominated scalar this may be the only way to measure its couplings to gauge bosons. Especially promising are channels where the initial scalar is radiated off a W as these events have relatively high rates and provide substantial background suppression due to leptons from the W. We identify three benchmark points that well represent the above scenarios. Assuming that the masses of the scalars and pseudoscalars are already measured in the gluon-fusion channel, the event kinematics can be further constrained, hence significantly improving detection prospects. This is especially important in the Higgs-strahlung channels with rather heavy scalars, and results in possible detection at 200 fb−1 for the most favoured parts of the parameter space.

Background constrains of the SuperNEMO experiment for neutrinoless double beta-decay searches

The SuperNEMO experiment is a new generation of experiments dedicated to the search for neutrinoless double beta-decay, which if observed, would confirm the existence of physics beyond the Standard Model. It is based on the tracking and calorimetry techniques, which allow the reconstruction of the final state topology, including timing and kinematics of the double beta-decay transition events, offering a powerful tool for background rejection. While the basic detection strategy of the SuperNEMO detector remains the same as of the NEMO-3 detector, a number of improvements were accomplished for each of detector main components. Upgrades of the detector technologies and development of low-level counting techniques ensure radiopurity control of construction parts of the SuperNEMO detector. A reference material made of glass pellets has been developed to assure quality management and quality control of radiopurity measurements. The first module of the SuperNEMO detector (Demonstrator) is currently under construction in the Modane underground laboratory. No background event is expected in the neutrinoless double beta-decay region in 2.5 years of its operation using 7kg of 82Se. The half-life sensitivity of the Demonstrator is expected to be >6.5·1024 y, corresponding to an effective Majorana neutrino mass sensitivity of |0.2−0.4|eV (90% C.L.). The full SuperNEMO experiment comprising of 20 modules with 100kg of 82Se source should reach an effective Majorana neutrino mass sensitivity of |0.04−0.1| eV, and a half-life limit 1·1026 y.

Side-sloped surfaces substantially affect lower limb running kinematics

Running on side-sloped surfaces is a common obstacle in the environment; however, how and to what extent the lower extremity kinematics adapt is not well known. The purpose of this study was to determine the effects of side-sloped surfaces on three-dimensional kinematics of hip, knee, and ankle during stance phase of running. Ten healthy adult males ran barefoot along an inclinable runway in level (0°) and side-sloped (10° up-slope and down-slope inclinations, respectively) configurations. Right hip, knee, and ankle angles along with their time of occurrence were analysed using repeated measures MANOVA. Up-slope hip was more adducted (p = 0.015) and internally rotated (p = 0.030). Knee had greater external rotations during side-sloped running at heel-strike (p = 0.005), while at toe-off, it rotated externally and internally during up-slope and down-slope running, respectively (p = 0.001). Down-slope ankle had greatest plantar flexion (p = 0.001). Up-slope ankle had greatest eversion compared with down-slope (p = 0.043), while it was more externally rotated (p = 0.030). These motion patterns are necessary to adjust the lower extremity length during side-sloped running. Timing differences in the kinematic events of hip adduction and external rotation, and ankle eversion were observed (p = 0.006). Knowledge on these alterations is a valuable tool in adopting strategies to enhance performance while preventing injury.

Determination of theWWpolarization fractions inpp→W±W±jjusing a deep machine learning technique

The unitarization of the longitudinal vector boson scattering (VBS) cross section by the Higgs boson is a fundamental prediction of the Standard Model which has not been experimentally verified. One of the most promising ways to measure VBS uses events containing two leptonically-decaying same-electric-charge $W$ bosons produced in association with two jets. However, the angular distributions of the leptons in the $W$ boson rest frame, which are commonly used to fit polarization fractions, are not readily available in this process due to the presence of two neutrinos in the final state. In this paper we present a method to alleviate this problem by using a deep machine learning technique to recover these angular distributions from measurable event kinematics and demonstrate how the longitudinal-longitudinal scattering fraction could be studied. We show that this method doubles the expected sensitivity when compared to previous proposals.

Dynamic color screening in diffractive deep inelastic scattering

We present a novel Monte-Carlo implementation of dynamic colour screening via multiple exchanges of semi-soft gluons as a basic QCD mechanism to understand diffractive electron-proton scattering at the HERA collider. Based on the kinematics of individual events in the standard QCD description of deep inelastic scattering at the parton level, which at low $x$ is dominantly gluon-initiated, the probability is evaluated for additional exchanges of softer gluons resulting in an overall colour singlet exchange leading to a forward proton and a rapidity gap as the characteristic observables for diffractive scattering. The probability depends on the impact parameter of the soft exchanges and varies with the transverse size of the hard scattering subsystem and is therefore influenced by different QCD effects. We account for matrix elements and parton shower evolution either via conventional DGLAP $\log Q^2$-evolution with collinear factorisation or CCFM small-$x$ evolution with $k_\perp$-factorisation and discuss the sensitivity to the gluon density distribution in the proton and the importance of large log\,$x$-contributions. The overall result is that, with only two model parameters which have theoretically motivated values, a satisfactory description of the observed diffractive cross-section at HERA is obtained in a wide kinematical range.

Search for Strongly-Produced Supersymmetric Particles in Decays with Two Leptons at [formula omitted

This contribution presents a search for squarks and gluinos in final states containing two isolated electrons or muons using the 20.3 fb-1 of s=8 TeV proton-proton collisions recorded by the ATLAS detector at the LHC during 2012. The search uses a set of variables carrying information on the event kinematics both transverse and parallel to the beam line. No excess above the Standard Model expectation is observed, therefore exclusion limits are set on sparticle masses for various simplified model scenarios and a minimal universal extra dimensions model.

A comparison between Smoothed-Particle Hydrodynamics and RANS Volume of Fluid method in modelling slamming

The oil and gas industry requires complex subsea infrastructure in order to develop offshore oil and gas fields. Upon installation, these components may encounter high slamming loads, stemming from impact with the water surface. This paper utilises two different numerical methods, the mesh-free Smoothed Particle Hydrodynamics (SPH) approach and Reynolds Averaged Navier–Stokes (RANS) Volume of Fluid (VOF) method to quantify these loads on a free-falling object. The investigation is also interested in conducting a parameter study and determining the effect of varying simulation parameters on the prediction of slamming event kinematics and forces. The surface impact of a freefalling wedge was introduced as a case study and has been simulated using SPH and RANS, with the results being compared to an experimental investigation. It was found from the SPH simulations that particle resolution and the size of the SPH particle kernel are very important, whilst the diffusion term does not play an important role. The latter is due to the very transient nature of slamming events, which do not allow sufficient time for diffusion in the fluid domain. For the RANS simulations, motion of the wedge was achieved using the overset grid technique, whereby varying the discretising time step was found to have a pronounced impact on the accuracy of the captured slamming event. Through analysing the numerical data, one can observe that the RANS results correlate slightly better with the experimental data as opposed to that obtained from the SPH modelling. However, considering the robustness and quick set up of the SPH simulations, both of these two numerical approaches are considered to be promising tools for modelling more complicated slamming problems, including those potentially involving more intricate structures.

Pynoddy 1.0: an experimental platform for automated 3-D kinematic and potential field modelling

Abstract. We present a novel methodology for performing experiments with subsurface structural models using a set of flexible and extensible Python modules. We utilize the ability of kinematic modelling techniques to describe major deformational, tectonic, and magmatic events at low computational cost to develop experiments testing the interactions between multiple kinematic events, effect of uncertainty regarding event timing, and kinematic properties. These tests are simple to implement and perform, as they are automated within the Python scripting language, allowing the encapsulation of entire kinematic experiments within high-level class definitions and fully reproducible results. In addition, we provide a link to geophysical potential-field simulations to evaluate the effect of parameter uncertainties on maps of gravity and magnetics. We provide relevant fundamental information on kinematic modelling and our implementation, and showcase the application of our novel methods to investigate the interaction of multiple tectonic events on a pre-defined stratigraphy, the effect of changing kinematic parameters on simulated geophysical potential fields, and the distribution of uncertain areas in a full 3-D kinematic model, based on estimated uncertainties in kinematic input parameters. Additional possibilities for linking kinematic modelling to subsequent process simulations are discussed, as well as additional aspects of future research. Our modules are freely available on github, including documentation and tutorial examples, and we encourage the contribution to this project.

Measurement of the charge asymmetry in top-quark pair production in the lepton-plus-jets final state in pp collision data at [Formula: see text] with the ATLAS detector.

This paper reports inclusive and differential measurements of the tbar{t} charge asymmetry A_{text {C}} in 20.3~{mathrm{fb}^{-1}} of sqrt{s} = 8~mathrm TeV{} pp collisions recorded by the ATLAS experiment at the Large Hadron Collider at CERN. Three differential measurements are performed as a function of the invariant mass, transverse momentum and longitudinal boost of the tbar{t} system. The tbar{t} pairs are selected in the single-lepton channels (e or mu ) with at least four jets, and a likelihood fit is used to reconstruct the tbar{t} event kinematics. A Bayesian unfolding procedure is performed to infer the asymmetry at parton level from the observed data distribution. The inclusive tbar{t} charge asymmetry is measured to be A_{text {C}}{} = 0.009 pm 0.005 (stat. + syst.). The inclusive and differential measurements are compatible with the values predicted by the Standard Model.

Automated detection of feeding strikes by larval fish using continuous high-speed digital video: a novel method to extract quantitative data from fast, sparse kinematic events.

Using videography to extract quantitative data on animal movement and kinematics constitutes a major tool in biomechanics and behavioral ecology. Advanced recording technologies now enable acquisition of long video sequences encompassing sparse and unpredictable events. Although such events may be ecologically important, analysis of sparse data can be extremely time-consuming and potentially biased; data quality is often strongly dependent on the training level of the observer and subject to contamination by observer-dependent biases. These constraints often limit our ability to study animal performance and fitness. Using long videos of foraging fish larvae, we provide a framework for the automated detection of prey acquisition strikes, a behavior that is infrequent yet critical for larval survival. We compared the performance of four video descriptors and their combinations against manually identified feeding events. For our data, the best single descriptor provided a classification accuracy of 77-95% and detection accuracy of 88-98%, depending on fish species and size. Using a combination of descriptors improved the accuracy of classification by ∼2%, but did not improve detection accuracy. Our results indicate that the effort required by an expert to manually label videos can be greatly reduced to examining only the potential feeding detections in order to filter false detections. Thus, using automated descriptors reduces the amount of manual work needed to identify events of interest from weeks to hours, enabling the assembly of an unbiased large dataset of ecologically relevant behaviors.

Observation and physical practice: different practice contexts lead to similar outcomes for the acquisition of kinematic information.

This study differentiated the contributions of physical and observational practice to the learning of a single-limb multi-joint coordination pattern. Three groups (physical-practice, observation-practice, observation-physical) practiced for 2days and were given two performance tests 24h after the second practice session. The performance tests revealed that physical and observational practice contributed similarly to identifying and using kinematic information related to the relative motion direction between joints (lead/lag relationship) and to the to-be-learned relative phase pattern (ϕ=90°). Physical practice resulted in more stable coordination during performance tests and in the ability to produce different joint amplitudes with less variability. A serendipitous finding was that maximum elbow flexion (point of movement reversal) emerged as a kinematic event around which elbow and wrist coordination were organized. Movement reversals often serve to anchor the movement dynamics, and this anchoring effect was evident following both physical and observational practice, yet physical practice resulted in an advantage with regard to this anchor point on several kinematic measures. The results are discussed within the context of contemporary behavioral theories (coordination dynamics, visual perception perspective) of observational learning.

Support for the slip hypothesis from whisker-related tactile perception of rats in a noisy environment.

Rodents use active whisker movements to explore their environment. The “slip hypothesis” of whisker-related tactile perception entails that short-lived kinematic events (abrupt whisker movements, called “slips”, due to bioelastic whisker properties that occur during active touch of textures) carry the decisive texture information. Supporting this hypothesis, previous studies have shown that slip amplitude and frequency occur in a texture-dependent way. Further, experiments employing passive pulsatile whisker deflections revealed that perceptual performance based on pulse kinematics (i.e., signatures that resemble slips) is far superior to the one based on time-integrated variables like frequency and intensity. So far, pulsatile stimuli were employed in a noise free environment. However, the realistic scenario involves background noise (e.g., evoked by rubbing across the texture). Therefore, if slips are used for tactile perception, the tactile neuronal system would need to differentiate slip-evoked spikes from those evoked by noise. To test the animals under these more realistic conditions, we presented passive whisker-deflections to head-fixed trained rats, consisting of “slip-like” events (waveforms mimicking slips occurring with touch of real textures) embedded into background noise. Varying the (i) shapes (ramp or pulse); (ii) kinematics (amplitude, velocity, etc.); and (iii) the probabilities of occurrence of slip-like events, we observed that rats could readily detect slip-like events of different shapes against noisy background. Psychophysical curves revealed that the difference of slip event and noise amplitude determined perception, while increased probability of occurrence (frequency) had barely any effect. These results strongly support the notion that encoding of kinematics dominantly determines whisker-related tactile perception while the computation of frequency or intensity plays a minor role.

Identification of multiparticle final states in completely exclusive reactions based on the topology and kinematics of events

Methodological part of analysis of the coherent photoproduction of a proton-antiproton pair based on experimental data obtained at CLAS facility of the Jefferson Linear Accelerator Laboratory (USA) is represented. The beam of tagged photons with energies up to 5.75 GeV used in the experiment was incident on 40 cm long liquid deuterium target. The description of methods for identification of multiparticle final states in completely exclusive reactions is given. It is shown how the kinematics of coherent photoproduction of \(\gamma \bar p\), π+π−, k+k− pairs was used for identification of final state particles and reactions.

Geometric reasoning about damped and forced harmonic motion in the complex plane

Complex-valued functions are commonly used to solve differential equations for one-dimensional motion of a harmonic oscillator with linear damping, a sinusoidal driving force, or both. However, the usual approach treats complex functions as an algebraic shortcut, neglecting geometrical representations of those functions and discarding imaginary parts. This article emphasizes the benefit of using diagrams in the complex plane for such systems, in order to build intuition about harmonic motion and promote spatial reasoning and the use of varied representations. Examples include the analysis of exact time sequences of various kinematic events in damped harmonic motion, sense-making about the phase difference between a driving force and the resulting motion, and understanding the discrepancy between the resonant frequency and the natural undamped frequency for forced, damped harmonic motion. The approach is suitable for supporting instruction in undergraduate upper-division classical mechanics.

Conjugate volcanic rifted margins, seafloor spreading, and microcontinent: Insights from new high‐resolution aeromagnetic surveys in the Norway Basin

AbstractWe have acquired and processed new aeromagnetic data that cover the entire oceanic Norway Basin located between the Møre volcanic rifted margin and the Jan Mayen microcontinent (JMMC). The new compilation allows us to revisit the structure of the conjugate volcanic (rifted) margins and the spreading evolution of the Norway Basin from the Early Eocene breakup time to the Late Oligocene when the Aegir Ridge became extinct. The volcanic margins (in a strict sense) that formed before the opening of the Norway Basin have been disconnected with the previous Jurassic‐Mid‐Cretaceous episode of crustal thinning. We also show evidence of relationships between the margin architecture, the breakup magmatism distribution along the continent‐oceanic transition, and the subsequent oceanic segmentation. The Norway Basin shows a complex system of asymmetric oceanic segments locally affected by episodic ridge jumps. The new aeromagnetic compilation also confirms that a fan‐shaped spreading evolution of the Norway Basin was clearly active before the cessation of seafloor spreading and extinction of the Aegir Ridge. An important Mid‐Eocene kinematic event at around magnetic chron C21r can be recognized in the Norway Basin. This event coincides with the onset of diking and increasing rifting activity (and possible oceanic accretion?) between the proto‐JMMC and the East Greenland margin. It led to a second phase of breakup and microcontinent formation in the Norwegian‐Greenland Sea ~26 Myrs later in the Oligocene.

Upper Extremity Muscle Activity During The Lacrosse Shot

PURPOSE: To determine if lacrosse shaft stiffness influenced upper extremity muscle activity and/or shot velocity. METHODS: Muscle activity of the biceps brachii, triceps brachii, flexor carpi radialis, and extensor carpi radialis of the arm closer to the head of the shaft was measured (EMG, 1500Hz). Subjects (n=5; 20±2.4 years, 79.8±6.87 kg, 177±4.52 cm) with 4.5±2.96 years of lacrosse experience completed shots using four shafts of different stiffnesses. Subjects and research team were blinded to shaft stiffness. Subjects shot 5 times per shaft with order of shaft randomized. Subjects were instructed to shoot with maximum effort from a stationary position (i.e., one step forward with the front foot; the back foot remained on the ground). Subjects were given time to warm up with practice shots on net. A video camera was used to record discrete kinematic events of the shot. Shot velocity was recorded for each shot and averaged across the 5 trials per condition. Video data was visually inspected and the time of occurrence of maximum elbow flexion, ball release, and maximum elbow extension were identified. EMG data were processed by removing any zero offset, full-wave rectifying the data and averaging across two phases defined by the kinematic discrete events. Muscle activity for each phase and shot velocity was compared between shafts using a repeated measures ANOVA (α=0.05). RESULTS: Neither muscle activity for any muscle analyzed nor shot velocity were influenced by shaft stiffness (p>0.05). CONCLUSION: Having a high shot velocity can be advantageous to a lacrosse player. Besides the player ability, lacrosse equipment may be a factor in determining shot velocity. However, in this experiment, shaft stiffness did not have an influence on muscle activity or shot velocity.

A universal approach to determine footfall timings from kinematics of a single foot marker in hoofed animals.

The study of animal movement commonly requires the segmentation of continuous data streams into individual strides. The use of forceplates and foot-mounted accelerometers readily allows the detection of the foot-on and foot-off events that define a stride. However, when relying on optical methods such as motion capture, there is lack of validated robust, universally applicable stride event detection methods. To date, no method has been validated for movement on a circle, while algorithms are commonly specific to front/hind limbs or gait. In this study, we aimed to develop and validate kinematic stride segmentation methods applicable to movement on straight line and circle at walk and trot, which exclusively rely on a single, dorsal hoof marker. The advantage of such marker placement is the robustness to marker loss and occlusion. Eight horses walked and trotted on a straight line and in a circle over an array of multiple forceplates. Kinetic events were detected based on the vertical force profile and used as the reference values. Kinematic events were detected based on displacement, velocity or acceleration signals of the dorsal hoof marker depending on the algorithm using (i) defined thresholds associated with derived movement signals and (ii) specific events in the derived movement signals. Method comparison was performed by calculating limits of agreement, accuracy, between-horse precision and within-horse precision based on differences between kinetic and kinematic event. In addition, we examined the effect of force thresholds ranging from 50 to 150 N on the timings of kinetic events. The two approaches resulted in very good and comparable performance: of the 3,074 processed footfall events, 95% of individual foot on and foot off events differed by no more than 26 ms from the kinetic event, with average accuracy between −11 and 10 ms and average within- and between horse precision ≤8 ms. While the event-based method may be less likely to suffer from scaling effects, on soft ground the threshold-based method may prove more valuable. While we found that use of velocity thresholds for foot on detection results in biased event estimates for the foot on the inside of the circle at trot, adjusting thresholds for this condition negated the effect. For the final four algorithms, we found no noteworthy bias between conditions or between front- and hind-foot timings. Different force thresholds in the range of 50 to 150 N had the greatest systematic effect on foot-off estimates in the hind limbs (up to on average 16 ms per condition), being greater than the effect on foot-on estimates or foot-off estimates in the forelimbs (up to on average ±7 ms per condition).

Characterising dark matter searches at colliders and direct detection experiments: vector mediators

We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: m DM , M med , g DM and g q, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (≲5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. Finally, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.

Future Prospects of di-jet Production Constraining Δg(x) at Low x in Polarized p + p Collisions at RHIC

One of the main objectives of the high-energy spin physics program at RHIC at BNL is the precise determination of the polarized gluon distribution function, Δg(x). Polarized [Formula: see text] collisions at [Formula: see text] GeV and at [Formula: see text] GeV at RHIC provide an unique way to probe the proton spin structure. Inclusive measurements, such as inclusive jet and hadron production, have so far been the prime focus of various results at [Formula: see text] GeV constraining Δg(x) for 0.05 < x < 0.2. A recent global analysis provides for the first time evidence of a non-zero value of the gluon polarization [Formula: see text]. First results of di-jet production at [Formula: see text] GeV by the STAR collaboration will allow a better constraint of the underlying event kinematics. Extending the current program to smaller values of x is a key goal for the future high-energy spin physics program at RHIC. Forward di-jet production measurements at STAR beyond the current acceptance from -1 < η < +2 to +2.5 < η < +4, in particular those carried out at [Formula: see text] GeV, provides access to low x values at the level of 10-3 where current uncertainties of Δg(x) remain very large. Those measurements will eventually be complemented by a future Electron-Ion Collider facility probing Δg(x) in polarized [Formula: see text] collisions.

Deceptive body movements reverse spatial cueing in soccer.

The purpose of the experiments was to analyse the spatial cueing effects of the movements of soccer players executing normal and deceptive (step-over) turns with the ball. Stimuli comprised normal resolution or point-light video clips of soccer players dribbling a football towards the observer then turning right or left with the ball. Clips were curtailed before or on the turn (−160, −80, 0 or +80 ms) to examine the time course of direction prediction and spatial cueing effects. Participants were divided into higher-skilled (HS) and lower-skilled (LS) groups according to soccer experience. In experiment 1, accuracy on full video clips was higher than on point-light but results followed the same overall pattern. Both HS and LS groups correctly identified direction on normal moves at all occlusion levels. For deceptive moves, LS participants were significantly worse than chance and HS participants were somewhat more accurate but nevertheless substantially impaired. In experiment 2, point-light clips were used to cue a lateral target. HS and LS groups showed faster reaction times to targets that were congruent with the direction of normal turns, and to targets incongruent with the direction of deceptive turns. The reversed cueing by deceptive moves coincided with earlier kinematic events than cueing by normal moves. It is concluded that the body kinematics of soccer players generate spatial cueing effects when viewed from an opponent's perspective. This could create a reaction time advantage when anticipating the direction of a normal move. A deceptive move is designed to turn this cueing advantage into a disadvantage. Acting on the basis of advance information, the presence of deceptive moves primes responses in the wrong direction, which may be only partly mitigated by delaying a response until veridical cues emerge.