| 1. |
- Aarrestad, Thea, et al.
(författare)
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Benchmark data and model independent event classification for the large hadron collider
- 2022
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Ingår i: SciPost Physics. - 2542-4653. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- We describe the outcome of a data challenge conducted as part of the Dark Machines (https://www.darkmachines.org) initiative and the Les Houches 2019 workshop on Physics at TeV colliders. The challenged aims to detect signals of new physics at the Large Hadron Collider (LHC) using unsupervised machine learning algorithms. First, we propose how an anomaly score could be implemented to define model-independent signal regions in LHC searches. We define and describe a large benchmark dataset, consisting of > 1 billion simulated LHC events corresponding to 10 fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV. We then review a wide range of anomaly detection and density estimation algorithms, developed in the context of the data challenge, and we measure their performance in a set of realistic analysis environments. We draw a number of useful conclusions that will aid the development of unsupervised new physics searches during the third run of the LHC, and provide our benchmark dataset for future studies at https://www.phenoMLdata.org. Code to reproduce the analysis is provided at https://github.com/bostdiek/DarkMachines-UnsupervisedChallenge.
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| 2. |
- Banerjee, Avik, 1992, et al.
(författare)
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Fingerprints of freeze-in dark matter in an early matter-dominated era
- 2022
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Ingår i: SciPost Physics. - 2542-4653. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- We study the impact of an alternate cosmological history with an early matter-dominated epoch on the freeze-in production of dark matter. Such early matter domination is triggered by a meta-stable matter field dissipating into radiation. In general, the dissipation rate has a non-trivial temperature and scale factor dependence. Compared to the usual case of dark matter production via the freeze-in mechanism in a radiation-dominated universe, in this scenario, orders of magnitude larger coupling between the visible and the dark sector can be accommodated. Finally, as a proof of principle, we consider a specific model where the dark matter is produced by a sub-GeV dark photon having a kinetic mixing with the Standard Model photon. We point out that the parameter space of this model can be probed by the experiments in the presence of an early matter-dominated era.
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| 3. |
- Bierlich, Christian, et al.
(författare)
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Jet modifications from colour rope formation in dense systems of non-parallel strings
- 2022
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Ingår i: SciPost Physics. - 2542-4653. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- We revisit our rope model for string fragmentation that has been shown to give a reasonable description of strangeness and baryon enhancement in high-multiplicity pp events at the LHC. A key feature of the model is that the enhancement is driven by the increased string tension due to strings overlapping in dense systems. By introducing an improved space–time picture for the overlap between fragmenting strings, where also non-parallel strings are properly taken into account, we are now able to investigate the enhancement both in jets and in the underlying event in a consistent way.
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| 4. |
- Choo, Kenny, et al.
(författare)
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Thermal and dissipative effects on the heating transition in a driven critical system
- 2022
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Ingår i: SciPost Physics. - : Stichting SciPost. - 2542-4653. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- We study the dissipative dynamics of a periodically driven inhomogeneous critical lattice model in one dimension. The closed system dynamics starting from pure initial states is well-described by a driven Conformal Field Theory (CFT), which predicts the existence of both heating and non-heating phases in such systems. Heating is inhomogeneous and is manifested via the emergence of black-hole like horizons in the system. The robustness of this CFT phenomenology when considering thermal initial states and open systems remains elusive. First, we present analytical results for the Floquet CFT time evolution for thermal initial states. Moreover, using exact calculations of the time evolution of the lattice density matrix, we demonstrate that for short and intermediate times, the closed system phase diagram comprising heating and non-heating phases, persists for thermal initial states on the lattice. Secondly, in the fully open system with boundary dissipators, we show that the nontrivial spatial structure of the heating phase survives particle-conserving and non-conserving dissipations through clear signatures in mutual information and energy density evolution.
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| 5. |
- Cranmer, Kyle, et al.
(författare)
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Publishing statistical models : Getting the most out of particle physics experiments
- 2022
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Ingår i: SciPost Physics. - 2542-4653. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The statistical models used to derive the results of experimental analyses are of incredible scientific value and are essential information for analysis preservation and reuse. In this paper, we make the scientific case for systematically publishing the full statistical models and discuss the technical developments that make this practical. By means of a variety of physics cases - including parton distribution functions, Higgs boson measurements, effective field theory interpretations, direct searches for new physics, heavy flavor physics, direct dark matter detection, world averages, and beyond the Standard Model global fits - we illustrate how detailed information on the statistical modelling can enhance the short- and long-term impact of experimental results.
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| 6. |
- Del Zotto, Michele, et al.
(författare)
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2-Group symmetries and M-theory
- 2022
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Ingår i: SciPost Physics. - : SciPost. - 2542-4653. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Quantum Field Theories engineered in M-theory can have 2-group symmetries, mixing 0-form and 1-form symmetry backgrounds in non-trivial ways. In this paper we develop methods for determining the 2-group structure from the boundary geometry of the Mtheory background. We illustrate these methods in the case of 5d theories arising from Mtheory on ordinary and generalised toric Calabi-Yau cones, including cases in which the resulting theory is non-Lagrangian. Our results confirm and elucidate previous results on 2-groups from geometric engineering.
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| 7. |
- Deng, Xiaolong, et al.
(författare)
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Anisotropy-mediated reentrant localization
- 2022
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Ingår i: SciPost Physics. - : Stichting SciPost. - 2542-4653. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- We consider a 2d dipolar system, d = 2, with the generalized dipole-dipole interaction similar to r(-a), and the power a controlled experimentally in trapped-ion or Rydberg-atom systems via their interaction with cavity modes. We focus on the dilute dipolar excitation case when the problem can be effectively considered as single-particle with the interaction providing long-range dipolar-like hopping. We show that the spatially homogeneous tilt beta of the dipoles giving rise to the anisotropic dipole exchange leads to the non-trivial reentrant localization beyond the locator expansion, a < d, unlike the models with random dipole orientation. The Anderson transitions are found to occur at the finite values of the tilt parameter beta = a, 0 < a < d, and beta = a =(a d =2), d =2 < a < d, showing the robustness of the localization at small and large anisotropy values. Both exact analytical methods and extensive numerical calculations show power-law localized eigenstates in the bulk of the spectrum, obeying recently discovered duality a <-> 2d -a of their spatial decay rate, on the localized side of the transition, a > a(AT). This localization emerges due to the presence of the ergodic extended states at either spectral edge, which constitute a zero fraction of states in the thermodynamic limit, decaying though extremely slowly with the system size.
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| 8. |
- Erdmenger, Johanna, et al.
(författare)
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Towards quantifying information flows : Relative entropy in deep neural networks and the renormalization group
- 2022
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Ingår i: SciPost Physics. - : Stichting SciPost. - 2542-4653. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the analogy between the renormalization group (RG) and deep neural networks, wherein subsequent layers of neurons are analogous to successive steps along the RG. In particular, we quantify the flow of information by explicitly computing the relative entropy or Kullback-Leibler divergence in both the one- and two-dimensional Ising models under decimation RG, as well as in a feedforward neural network as a function of depth. We observe qualitatively identical behavior characterized by the monotonic increase to a parameter-dependent asymptotic value. On the quantum field theory side, the monotonic increase confirms the connection between the relative entropy and the c-theorem. For the neural networks, the asymptotic behavior may have implications for various information maximization methods in machine learning, as well as for disentangling compactness and generalizability. Furthermore, while both the two-dimensional Ising model and the random neural networks we consider exhibit non-trivial critical points, the relative entropy appears insensitive to the phase structure of either system. In this sense, more refined probes are required in order to fully elucidate the flow of information in these models.
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| 9. |
- Gellersen, Leif, et al.
(författare)
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Coloring mixed QCD/QED evolution
- 2022
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Ingår i: SciPost Physics. - 2542-4653. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Parton showers are crucial components of high-energy physics calculations. Improving their modelling of QCD is an active research area since shower approximations are stumbling blocks for precision event generators. Naively, the interference between subdominant Standard-Model interactions and QCD can be of similar size to subleading QCD corrections. This article assesses the impact of QCD/QED interference effects in parton showers, by developing a sophisticated shower including QED, QCD at fixed color, and employing complete tree-level matrix element corrections for individual NC = 3 color configurations to embed interference. The resulting simulation indicates that QCD/QED interference effects are small for a simple test case and dwarfed by electro-weak resonance effects.
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| 10. |
- Grosvenor, Kevin T., et al.
(författare)
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The edge of chaos : Quantum field theory and deep neural networks
- 2022
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Ingår i: SciPost Physics. - : Stichting SciPost. - 2542-4653. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- We explicitly construct the quantum field theory corresponding to a general class of deep neural networks encompassing both recurrent and feedforward architectures. We first consider the mean-field theory (MFT) obtained as the leading saddlepoint in the action, and derive the condition for criticality via the largest Lyapunov exponent. We then compute the loop corrections to the correlation function in a perturbative expansion in the ratio of depth T to width N, and find a precise analogy with the well-studied O(N) vector model, in which the variance of the weight initializations plays the role of the 't Hooft coupling. In particular, we compute both the O(1) corrections quantifying fluctuations from typicality in the ensemble of networks, and the subleading O(T IN) corrections due to finite-width effects. These provide corrections to the correlation length that controls the depth to which information can propagate through the network, and thereby sets the scale at which such networks are trainable by gradient descent. Our analysis provides a first-principles approach to the rapidly emerging NN-QFT correspondence, and opens several interesting avenues to the study of criticality in deep neural networks.
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