SciPost Phys. Proc. 1, 015 (2019) ·
published 19 February 2019
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Neutrino oscillations provided the first evidence for the violation of flavour in the lepton sector, and established a clear need to consider extensions of the Standard Model. Many new phenomena can emerge from these New Physics (NP) constructions, among which processes violating lepton number and charged lepton flavour, all clear signals of New Physics. Following a short overview of the status of experimental searches, we comment on the prospects of several models of massive neutrinos, from minimal constructions to complete NP models, to the above mentioned observables.
SciPost Phys. 11, 056 (2021) ·
published 13 September 2021
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Many recent tensor network algorithms apply unitary operators to parts of a tensor network in order to reduce entanglement. However, many of the previously used iterative algorithms to minimize entanglement can be slow. We introduce an approximate, fast, and simple algorithm to optimize disentangling unitary tensors. Our algorithm is asymptotically faster than previous iterative algorithms and often results in a residual entanglement entropy that is within 10 to 40% of the minimum. For certain input tensors, our algorithm returns an optimal solution. When disentangling order-4 tensors with equal bond dimensions, our algorithm achieves an entanglement spectrum where nearly half of the singular values are zero. We further validate our algorithm by showing that it can efficiently disentangle random 1D states of qubits.
Carlo Flore, Maria Elena Boglione, Umberto D'Alesio, Josè Osvaldo Gonzalez-Hernandez, Francesco Murgia, Alexei Prokudin
SciPost Phys. Proc. 8, 034 (2022) ·
published 11 July 2022
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The Bayesian reweighting procedure is applied for the first time to a TMD distribution, the quark Sivers function extracted from SIDIS data. By exploiting the recent published single spin asymmetry data for the inclusive jet production in $p^\uparrow p$ collisions from the STAR collaboration at RHIC, we show how such a procedure allows to incorporate the information contained in the new data set, without the need of re-fitting, and to explore a much wider $x$ region compared to SIDIS measurements. The reweighting method is also extended to the case of asymmetric errors, and the results show a significant improvement on the knowledge of the quark Sivers function.
SciPost Phys. Proc. 1, 014 (2019) ·
published 19 February 2019
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Charged lepton flavour violating processes are naturally present in many extensions of the Standard Model. After a brief overview on the experimental situation, an effective-field-theory framework is described that allows to interpret and compare the various experiments in a consistent way. The usefulness of this approach is then illustrated in the context of a specific model with a doubly charged scalar.
Mig. Pol. 4, 006 (2025) ·
published 24 December 2025
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On October 9, 2021, the Bangladesh Ministry of Disaster Management and Relief, and the U.N. High Commissioner for Refugees (UNHCR) signed a Memorandum of Understanding (MoU) to establish a common framework for humanitarian services for Rohingya refugees on Bhasanchar, an island 37 miles from the mainland in the Bay of Bengal. Bangladesh’s plan to relocate 100,000 Rohingya to Bhasanchar offers an opportunity to analyze the complex nature of refugee-hosting in the Global South, bringing into focus how a Global South host, rather than being a passive actor, can attempt a context-specific strategy to generate normative and financial support for its role in accommodating a displaced population. This research aims to make three main contributions. First, it seeks to situate the case of the Rohingya refugee population in Bangladesh within the literature on migration diplomacy and refugee rentierism. Second, it seeks to modify and expand on the refugee rentier state literature by demonstrating how a host country can pursue a path of ‘normative modelling,’ rather than blackmailing or backscratching for purely economic aims. It shows that states may seek to set new norms for refugee hosting for the purpose of gaining international recognition and accolades, in addition to economic support. As such, it finds the existing models of refugee rentierism constrained by its roots in realist IR theory, and suggests a constructivist correction, in which identity and norm setting are relevant to understanding the state’s policy choices. Third, in examining the use of ‘internal offshoring’ i.e. using one’s own territory for redistribution of a population (in this case from a congested refugee camp), it problematizes how Global North practices of extraterritorial ‘offshoring’ such as Australia’s use of the Nauru and Manus islands for immigration detention have served as the framework for understanding Bangladesh’s strategy. While the research outlines the grounds for valid concerns about Bhasanchar, an examination of the political economy of land use in Bangladesh offers a nuanced understanding of the island relocation plan. Such an analysis underscores how imposing the border externalization practices framework inaccurately casts Bangladesh as a case of ‘negative norm absorption’ of migrant deterrence practices, rather than capturing how char (island) living has long been a part of riverine Bangladesh’s sociocultural and economic practices and obfuscates the country’s attempt at norm modeling for refugee accommodation.
José Ramón Pareja Monturiol, Alejandro Pozas-Kerstjens, David Pérez-García
SciPost Phys. Core 8, 095 (2025) ·
published 24 December 2025
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We present a tensorization algorithm for constructing tensor train/matrix product state (MPS) representations of functions, drawing on sketching and cross interpolation ideas. The method only requires black-box access to the target function and a small set of sample points defining the domain of interest. Thus, it is particularly well-suited for machine learning models, where the domain of interest is naturally defined by the training dataset. We show that this approach can be used to enhance the privacy and interpretability of neural network models. Specifically, we apply our decomposition to (i) obfuscate neural networks whose parameters encode patterns tied to the training data distribution, and (ii) estimate topological phases of matter that are easily accessible from the MPS representation. Additionally, we show that this tensorization can serve as an efficient initialization method for optimizing MPS in general settings, and that, for model compression, our algorithm achieves a superior trade-off between memory and time complexity compared to conventional tensorization methods of neural networks.
Rafał Maciuła, Victor P. Goncalves, Antoni Szczurek
SciPost Phys. Proc. 8, 124 (2022) ·
published 13 July 2022
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The predictions for the atmospheric neutrino flux at high energies strongly depend on the contribution of prompt neutrinos, which are determined by the production of charmed meson in the atmosphere at very forward rapidities. Here we estimate the related cross sections taking into account the presence of an intrinsic charm (IC) component in the proton wave function. The impact on the predictions for the prompt neutrino flux is investigated assuming different values for the probability to find the IC in the nucleon.
SciPost Phys. 20, 024 (2026) ·
published 28 January 2026
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We analyze topological phase transitions and higher Berry curvature in one-dimensional quantum spin systems, using a framework that explicitly incorporates the symmetry group action on the parameter space. Based on a $G$-compatible discretization of the parameter space, we incorporate both group cochains and parameter-space differentials, enabling the systematic construction of equivariant topological invariants. We derive a fixed-point formula for the higher Berry invariant in the case where the symmetry action has isolated fixed points. This reveals that the phase transition point between Haldane and trivial phases acts as a monopole-like defect where higher Berry curvature emanates. We further discuss hierarchical structures of topological defects in the parameter space, governed by symmetry reductions and compatibility with subgroup structures.
SciPost Phys. Proc. 1, 009 (2019) ·
published 18 February 2019
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These proceedings present the differential decay rates and the branching ratios of the tau and muon decays $\tau \to \ell \ell' \ell' \nu \bar\nu$ (with $\ell,\ell'=\mu,e$) and $\mu \to e e e \nu \bar \nu$ in the Standard Model at NLO. These five-body leptonic decays are a tool to study the Lorentz structure of weak interactions and to test lepton flavour universality. They are also a source of SM background to searches for the lepton-flavour-violating decays $\mu \to e e e$ and $\tau \to \ell \ell' \ell'$. Even if the shift in the branching ratios induced by radiative corrections turns out to be small and of order 1% - mainly due to a running effect of the fine structure constant - locally in the phase space these corrections can reach the 5 - 10% level, depending on the applied cuts. We found for instance that in the phase space region where the neutrino energies are small, and the momenta of the three charged leptons have a similar signature as in $\mu \to eee$ and $\tau \to \ell \ell'\ell'$, the NLO corrections decrease the leading-order prediction by about 10 - 20%.
SciPost Phys. 18, 202 (2025) ·
published 23 June 2025
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The BV formalism is a well-established method for analyzing symmetries and quantizing field theories. In this paper, we use BV formalism to derive partition functions and the space of gauge invariant operators implementing the equations of motions and their redundancies for selected theories. We discuss various interpretations of the results, some dualities, and relation to the first quantized models.
