Publications

Order by: publication date number of citations

• Scale invariant distribution functions in quantum systems with few degrees of freedom

  Emanuele G. Dalla Torre

  SciPost Phys. 5, 023 (2018) · published 14 September 2018 | Toggle abstract · pdf

  Scale invariance usually occurs in extended systems where correlation functions decay algebraically in space and/or time. Here we introduce a new type of scale invariance, occurring in the distribution functions of physical observables. At equilibrium these functions decay over a typical scale set by the temperature, but they can become scale invariant in a sudden quantum quench. We exemplify this effect through the analysis of linear and non-linear quantum oscillators. We find that their distribution functions generically diverge logarithmically close to the stable points of the classical dynamics. Our study opens the possibility to address integrability and its breaking in distribution functions, with immediate applications to matter-wave interferometers.

  1 citation

• Resonant spin Hall effect of light in random photonic arrays

  Federico Carlini, Nicolas Cherroret

  SciPost Phys. 14, 104 (2023) · published 10 May 2023 | Toggle abstract · pdf

  It has been recently shown that the coherent component of light propagating in transversally disordered media, the so-called coherent mode, exhibits an optical spin Hall effect (SHE). In non-resonant materials, however, this phenomenon shows up at a spatial scale much larger than the mean free path, making its observation challenging due to the exponential attenuation of the coherent mode. Here, we show that in disordered photonic arrays exhibiting Mie resonances, the SHE on the contrary appears at a scale smaller than the mean free path if one operates in the close vicinity of the lowest transverse-magnetic resonance of the array. In combination with a weak measurement, this gives rise to a giant SHE that should be observable in optically-thin media. Furthermore, we show that by additionally exploiting the cooperative emission of a flash of light following the abrupt extinction of the incoming beam, one can achieve a time-dependent SHE, observable at large optical thickness as well.

• A new method to extract the valence transversity distributions

  Mauro Anselmino, Raj Kishore, Asmita Mukherjee

  SciPost Phys. Proc. 8, 052 (2022) · published 12 July 2022 | Toggle abstract · pdf

  A new method is suggested for the extraction of $u$-quark and $d$-quark transversity distributions, using single spin asymmetry (SSA) data in semi-inclusive deep inelastic scattering (SIDIS) processes, where they couple to the Collins or the di-hadron fragmentation functions. We discuss a recent suggestion to extract the transversity distribution using the concept of difference asymmetries and their ratios, which avoids the requirement of Collins function. We suggest new measurements, involving ratios of polarized cross-sections, that would directly probe the ratio $h_1^{d_v}/h_1^{u_v}$. We also show some numerical estimates.

• Limits to gauge coupling in the dark sector of super-heavy dark matter particles from the Pierre Auger Observatory data

  Olivier Deligny for the Pierre Auger Collaboration

  SciPost Phys. Proc. 13, 013 (2023) · published 28 September 2023 | Toggle abstract · pdf

  Assuming that the energy density of super-heavy particles matches that of dark matter observed today, tight constraints on the couplings governing the decay process are presented as a function of the particle mass. These constraints are obtained from the lack of signatures that would be suggestive of decaying super-heavy $X$ particles in the data of the Pierre Auger Observatory. In particular, instanton-induced decay processes allow us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: $\alpha_X \lesssim 0.09$, for $10^{9} \lesssim M_X/\mathrm{GeV} < 10^{19}$. Cosmological aspects for super-heavy dark matter production during the reheating epoch are discussed.

• WG2 Summary: Small-x, Diffraction and Vector Mesons

  Tolga Altinoluk, Marta Luszczak, Daniel Tapia Takaki

  SciPost Phys. Proc. 8, 110 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Here we briefly summarize the contributions to Working Group 2: Small-x, Diffraction and Vector Mesons, at the DIS2021 Workshop.

• Sivers asymmetry in inelastic $J/ψ$ leptoproduction at the EIC

  Sangem Rajesh, Umberto D'Alesio, Asmita Mukherjee, Francesco Murgia, Cristian Pisano

  SciPost Phys. Proc. 8, 017 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We study the Sivers asymmetry in inelastic $J/\psi$ leptoproduction, $ep^\uparrow \to e+ J/\psi+X$, within a transverse momentum dependent scheme, the so-called generalized parton model (GPM). The effects of final-state interactions are properly taken into account by employing the color-gauge invariant GPM (CGI-GPM). For the $J/\psi$ formation the non-relativistic QCD (NRQCD) framework is adopted. Predictions for unpolarized cross sections and maximized Sivers asymmetries at EIC energies are given.

• Ambiguous Ages, Ambivalent Youths: How Asylum Seekers in Germany Navigate Age Categorization

  Ulrike Bialas

  Mig. Pol. 2, 003 (2023) · published 5 September 2023 | Toggle abstract · pdf

  Many of the unaccompanied young migrants who have sought asylum in Germany since 2015 do not own documentation of their birth dates or even know their exact ages. Yet asylum and youth welfare laws distinguish precisely between minors and adults, down to the day, thus making it necessary for the German state to estimate the birth dates of young migrants and compelling some of the migrants to claim to be minors. In this article, drawing on years of ethnographic fieldwork in Berlin, I examine four features of the German state’s age categorization regime that make it so powerful: the discretion of street-level bureaucrats; the weight of written records; a prioritization of precision over accuracy; and—most important—the ability of bureaucrats to switch between the previous three features at will. I analyze the strategies young migrants employ against this regime to influence the outcomes of their own age categorization as well as the challenges inherent in living as a minor or within liminal, uncertain age categories. The latter include widespread distrust and fear of being found out as well as feelings of infantilization and emasculation. I use age categorization as a context in which to reflect on the agency of migrants vis-à-vis state bureaucracies and conclude that young migrants can try to affect only the determination of their own birth dates but have little impact on the prevailing definitions of age and youth. This article thus contributes to the study of categorization processes in international migration, the possibilities for migrants’ resistance, and the politics of time.

• Results on high energy galactic cosmic rays from the DAMPE space mission

  Leandro Silveri on behalf of the DAMPE Collaboration

  SciPost Phys. Proc. 13, 012 (2023) · published 28 September 2023 | Toggle abstract · pdf

  DAMPE (Dark Matter Particle Explorer) is a satellite-born experiment launched in 2015 in a sun-synchronous orbit at 500 km altitude, and it has been taking data in stable conditions ever since. Its main goals include the spectral measurements up to very high energies, cosmic electrons/positrons and gamma rays up to tens of TeV, and protons and nuclei up to hundreds of TeV. The detector's main features include the 32 radiation lengths deep calorimeter and large geometric acceptance, making DAMPE one of the most powerful space instruments in operation, covering with high statistics and small systematics the high energy frontier up to several hundreds TeV. The results of spectral measurements of different species are shown and discussed.

• Quantum simulation of colour in perturbative quantum chromodynamics

  Herschel A. Chawdhry, Mathieu Pellen

  SciPost Phys. 15, 205 (2023) · published 24 November 2023 | Toggle abstract · pdf

  Quantum computers are expected to give major speed-ups for the simulation of quantum systems. In this work, we present quantum gates that simulate the colour part of the interactions of quarks and gluons in perturbative quantum chromodynamics (QCD). As a first application, we implement these circuits on a simulated noiseless quantum computer and use them to calculate colour factors for various examples of Feynman diagrams. This work constitutes a first key step towards a quantum simulation of generic scattering processes in perturbative QCD.

• Quantum spin nematic liquid in the low-dimensional anisotropic magnets -S=1/2 delta spin chain with the anisotropic ferromagnetic interaction in magnetic field-

  Toru Sakai, Rito Furuchi, Hiroki Nakano, Kiyomi Okamoto

  SciPost Phys. Proc. 11, 001 (2023) · published 5 June 2023 | Toggle abstract · pdf

  The magnetization process of the $S=1/2$ delta chain with the anisotropic ferromagnetic interaction is investigated using the numerical diagonalization of finite-size clusters. It is found that the spin nematic liquid phase appears in higher magnetization region, as well as the SDW liquid one in lower region.