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Data-driven modeling of a laser-plasma accelerator-based x-ray source
No full textLaser-plasma accelerators (LPAs) enable compact, bright x-ray sources, but their practical application demands a significant reduction of beam instabilities that originate from drive laser fluctuations. Moreover, the complexity of the laser-plasma interaction makes it difficult to disentangle and quantify the impact of individual parameters on machine performance. To address this challenge, we develop a data-driven modeling strategy and apply it to an extensive dataset collected during a daylong operation of the LPAbased x-ray source LUX. By making use of an orthogonal-distance-based training objective, our approach reduces bias originating from measurement errors, which allows us to estimate the functional dependencies between laser, accelerated electrons, and generated undulator radiation. In addition, we demonstrate accurate prediction of the x-ray spectrum based on noninvasive measurements, showcasing the potential of our approach for building virtual diagnostics
Search for single production of vector-like quarks decaying into in collisions at TeV with the ATLAS detector
No full textA search for single production of a vector-like quark , which could be either a singlet , with charge , or a from a triplet, with charge , is performed using data from proton-proton collisions at a centre-of-mass energy of 13 TeV. The data correspond to the full integrated luminosity of 140 fb recorded with the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis targets decays where the boson decays leptonically. The data are found to be consistent with the expected Standard Model background, so upper limits are set on the cross-section times branching ratio, and on the coupling of the to the Standard Model sector for these two benchmark models. Effects of interference with the Standard Model background are taken into account. For the singlet , the 95% confidence level limit on the coupling strength ranges between 0.22 and 0.52 for masses from 1150 to 2300 GeV. For the triplet, the limits on vary from 0.14 to 0.46 for masses from 1150 to 2600 GeV
Parton-shower and hadronisation modelling uncertainty studies with Herwig7
No full textUncertainties in the predictions of general-purpose Monte-Carlo event generators, particularly those related to parton showering or hadronisation and other non-perturbative effects, are a leading source of systematic uncertainty in many ATLAS analyses. These modelling uncertainties are often estimated using a two-point approach, where the difference between two generators that use different models for these effects is used as the uncertainty. However, this approach can lead to the cancellation or double counting of effects, resulting in uncertainties that are poorly justified. This note investigates an alternative approach to this uncertainty where internal parton-shower and hadronisation model variations within a single generator, in this case Herwig 7, are used to provide a factorised and physics-motivated uncertainty. The approach is studied for both Z boson and ttbar production and compared to the two-point method
The impact of cosmic variance on PTAs anisotropy searches
No full textSeveral Pulsar Timing Array (PTA) collaborations have recently found evidence for a Gravitational Wave Background (GWB) by measuring the perturbations that this background induces in the time-of-arrivals of pulsar signals. These perturbations are expected to be correlated across different pulsars and, for isotropic GWBs, the expected values of these correlations (obtained by averaging over different GWB realizations) are a simple function of the pulsars' angular separations, known as the Hellings-Downs (HD) correlation function. On the other hand, anisotropic GWBs would induce deviations from these HD correlations in a way that can be used to search for anisotropic distributions of the GWB power. However, even for isotropic GWBs, interference between GW sources radiating at overlapping frequencies induces deviations from the HD correlation pattern, an effect known in the literature as 'cosmic variance'. In this work, we study the impact of cosmic variance on PTA anisotropy searches. We find that the fluctuations in cross-correlations related to cosmic variance can lead to the miss-classification of isotropic GWBs as anisotropic, leading to a false detection rate of for frequentist anisotropy searches. We also observe that cosmic variance complicates the reconstruction of the GWB sky map, making it more challenging to resolve bright GW hotspots, like the ones expected to be produced from a Supermassive Black Hole Binaries population. These findings highlight the need to refine anisotropy search techniques to improve our ability to reconstruct the GWB sky map and accurately assess the significance of any isotropy deviations we might find in it
Targeted degradation of GSPT1 and NEK7 by a molecular glue prodrug for treatment of HCC
No full textTargeted Protein Degradation (TPD) technology, in the form of CRBN-modulating molecular glues, offers numerous unprecedented therapeutic benefits as evidenced by the success of approved high-value immunomodulatory imide drugs (IMiDs) such as lenalidomide and pomalidomide. Building upon these successes, we employed a small CRBN-focused library of molecular glues in a phenotypic screen against hepatocellular carcinoma (HCC) cell lines. While the original library was primarily designed to target SALL4, we identified additional CRBN substrates, including GSPT1, NEK7, and CK1α, whose degradation potently induced cell death in HCC cell lines. Subsequent lead optimization efforts yielded a compound, ABS-752, which demonstrated superior in vitro and in vivo activity through the potent degradation of GSPT1. Notably, ABS-752 does not form ternary complexes with CRBN and the neosubstrates. Further investigations revealed that ABS-752 is a prodrug activated by the monoamine oxidase, VAP-1, to an aldehyde intermediate and subsequently to the active molecule, ABT-002. VAP-1, which is overexpressed in cirrhotic liver, was identified as the primary monoamine oxidase responsible for the conversion of ABS-752. ABS-752 is currently in clinical trials for the treatment of HCC
Precision calibration of calorimeter signals in the ATLAS experiment using an uncertainty-aware neural network
No full textThe ATLAS experiment at the Large Hadron Collider explores the use of modern neural networks for a multi-dimensional calibration of its calorimeter signal defined by clusters of topologically connected cells (topo-clusters). The Bayesian neural network (BNN) approach not only yields a continuous and smooth calibration function that improves performance relative to the standard calibration but also provides uncertainties on the calibrated energies for each topo-cluster. The results obtained by using a trained BNN are compared to the standard local hadronic calibration and to a calibration provided by training a deep neural network. The uncertainties predicted by the BNN are interpreted in the context of a fractional contribution to the systematic uncertainties of the trained calibration. They are also compared to uncertainty predictions obtained from an alternative estimator employing repulsive ensembles
Ultrashort laser pulse amplified by back-and-forth propagation
No full textUltrashort laser pulses are indispensable tools for sensing and measurement, but it is challenging to generate them at high powers. Quantum mechanics dictates that the more localized a laser pulse is in time, the wider the range of frequencies of its photons — ultrashort laser pulses are said to be ‘broadband’ because of their wide frequency range. The power of ultrashort laser pulses can be increased through amplification, but efficiently amplifying these pulses is difficult. However, in a paper in Nature, Nägele et al.1 report a method that efficiently amplifies a weak, ultrashort laser pulse by overlapping it with a high-power laser pulse. The authors achieved this by bouncing the two pulses back and forth between two mirrors such that they repeatedly passed through a crystal. The mirrors were designed to reduce unwanted mismatch between the pulses, and the researchers demonstrate that this set-up transfers energy to the weaker pulse with high efficiency
A Rosetta Stone for Wilson Line Defects
No full textIn this paper, we discuss the construction of a map between weak (gauge) and strong (string) coupling degrees of freedom for the supersymmetric Wilson line-defect in the planar N=4 Super-Yang-Mills. By analysing the Partition Functions at zero and infinite coupling, we propose a map from degrees of freedom capturing single- and singlet two-particle states at zero coupling to infinite coupling. This map predicts that the dimension of states in these particular sectors doubles as it goes from zero to infinite coupling. We test this prediction against the non-perturbative spectrum of insertions on the Wilson line obtained using integrability. In addition to already available integrability-based results, we obtain the non-perturbative scaling dimension of the simplest non-trivial operator with transverse spin about the Wilson line, thereby extending the Quantum Spectral Curve construction to such charged sectors