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.
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.
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.
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.
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%.
Lin Chen, Ling-Yan Hung, Yikun Jiang, Bing-Xin Lao
SciPost Phys. 19, 163 (2025) ·
published 23 December 2025
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We demonstrate that, by utilizing the boundary conformal field theory (BCFT) operator algebra of the Liouville CFT, one can express its path-integral on any Riemann surface as a three dimensional path-integral with appropriate boundary conditions, generalising the recipe for rational CFTs. This serves as a constructive method for deriving the quantum holographic dual of the CFT, which reduces to Einstein gravity in the large central charge limit. As a byproduct, the framework provides an explicit discrete state-sum of a 3D non-chiral topological theory constructed from quantum $6j$ symbols of $\mathcal{U}_q(sl(2,\mathbb{R}))$ with non-trivial boundary conditions, representing a long-sought non-perturbative discrete formulation of 3D pure gravity with negative cosmological constant, at least within a class of three manifolds. This constitutes the first example of an exact holographic tensor network that reproduces a known irrational CFT with a precise quantum gravitational interpretation.
SciPost Phys. 4, 016 (2018) ·
published 27 March 2018
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At thermal equilibrium, the concept of effective central charge for massive deformations of two-dimensional conformal field theories (CFT) is well understood, and can be defined by comparing the partition function of the massive model to that of a CFT. This temperature-dependent effective charge interpolates monotonically between the central charge values corresponding to the IR and UV fixed points at low and high temperatures, respectively. We propose a non-equilibrium, time-dependent generalization of the effective central charge for integrable models after a quantum quench, $c_{\rm eff}(t)$, obtained by comparing the return amplitude to that of a CFT quench. We study this proposal for a large mass quench of a free boson, where the charge is seen to interpolate between $c_{\rm eff}=0$ at $t=0$, and $c_{\rm eff}\sim 1$ at $t\to\infty$, as is expected. We use our effective charge to define an "Ising to Tricritical Ising" quench protocol, where the charge evolves from $c_{\rm eff}=1/2$ at $t=0$, to $c_{\rm eff}=7/10$ at $t\to\infty$, the corresponding values of the first two unitary minimal CFT models. We then argue that the inverse "Tricritical Ising to Ising" quench is impossible with our methods. These conclusions can be generalized for quenches between any two adjacent unitary minimal CFT models. We finally study a large mass quench into the "staircase model" (sinh-Gordon with a particular complex coupling). At short times after the quench, the effective central charge increases in a discrete "staircase" structure, where the values of the charge at the steps can be computed in terms of the central charges of unitary minimal CFT models. When the initial state is a pure state, one always finds that $c_{\rm eff}(t\to\infty)\geq c_{\rm eff}(t=0)$, though $c_{\rm eff}(t)$, generally oscillates at finite times. We explore how this constraint may be related to RG flow irreversibility.
SciPost Phys. 17, 091 (2024) ·
published 25 September 2024
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We study the effects of correlations in a random environment on a random walker. The dependence of its asymptotic speed on the correlations is a nonperturbative effect as it is not captured by a homogeneous version of the same environment. For a slowly cooling environment, the buildup of correlations modifies the walker's speed and, by so, realizes acceleration. We remark on the possible relevance in the discussion of cosmic acceleration as traditionally started from the Friedmann equations, which, from a statistical mechanical point of view, would amount to a mean-field approximation. Our environment is much simpler though, with transition rates sampled from the one-dimensional Ising model and allowing exact results and detailed velocity characteristics.
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.
