Publications

Order by: publication date number of citations

• Area law and OPE blocks in conformal field theory

  Jiang Long

  SciPost Phys. Proc. 4, 013 (2021) · published 13 August 2021 | Toggle abstract · pdf

  This is an introduction to the relationship between area law and OPE blocks in conformal field theory.

• Quantum revivals in HgTe/CdTe quantum wells and topological phase transitions

  Alberto Mayorgas, Manuel Calixto, Nicolás A. Cordero, Elvira Romera, Octavio Héctor Castaños Garza

  SciPost Phys. Core 7, 029 (2024) · published 13 May 2024 | Toggle abstract · pdf

  The time evolution of a wave packet is a tool to detect topological phase transitions in two-dimensional Dirac materials, such as graphene and silicene. Here we extend the analysis to HgTe/CdTe quantum wells and study the evolution of their electron current wave packet, using 2D effective Dirac Hamiltonians and different layer thicknesses. We show that the two different periodicities that appear in this temporal evolution reach a minimum near the critical thickness, where the system goes from normal to inverted regime. Moreover, the maximum of the electron current amplitude changes with the layer thickness, identifying that current maxima reach their higher value at the critical thickness. Thus, we can characterize the topological phase transitions in terms of the periodicity and amplitude of the electron currents.

• Development of the ATLAS Liquid Argon Calorimeter Readout Electronics for the HL-LHC

  Mathis Kolb

  SciPost Phys. Proc. 8, 158 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The full ATLAS Liquid Argon Calorimeter electronic readout chain will be upgraded for the high-luminosity LHC. The upgrade is designed to withstand the expected radiation level and to be compatible with the Phase-I Digital Trigger System which is being installed right now. Analogue electronics shape and amplify the calorimeter signals before they are digitized with 16 bit dynamic range on two gain scales. The on-detector system samples the calorimeter cell signals at 40 MHz and sends them to the off-detector electronics which apply digital processing based on FPGAs. Design studies and tests of prototypes of the upgraded components are present

• Hadron Polarimetry for the Electron-Ion Collider

  A.S. Nunes, E.C. Aschenauer, O. Eyser, W. Schmidke

  SciPost Phys. Proc. 8, 163 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The Electron-Ion Collider (EIC) will be the first collider to use both polarized electron beams and polarized proton and light ion beams. It will therefore offer unique opportunities to study the structure of nucleons and to answer fundamental questions in QCD. The uncertainties on the polarization measurement translate directly into the uncertainties of final physics observables. Hence, a precise measurement of the hadron beam polarization and a good control of systematic uncertainties are critical for the success of the spin program at the EIC. Contrary to the case of electron beam polarimetry, which uses physical processes derived from first principles that allow a high precision extraction of the electron beam polarization, for hadron beams no such process is available. The currently best used methods rely on the process of elastic scattering in the Coulomb-Nuclear Interference (CNI) region, for which there are only effective models available. The experience from RHIC, the only existing polarized proton collider, will be detailed and the challenges of the measurements at the EIC will be addressed. In particular, measurements of the present RHIC polarimeters and simulations of the future EIC polarimeters will be presented.

• Transverse spin asymmetries for inclusive $\rho^0$ production in SIDIS at COMPASS

  A. Kerbizi

  SciPost Phys. Proc. 8, 146 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The production of vector mesons in SIDIS is a particularly interesting channel to study the polarized fragmentation and related phenomena. Preliminary COMPASS results for the first measurement of inclusive $\rho^0$ Collins and Sivers transverse-spin asymmetries are presented here for the first time. The analysis is based on the data-set collected by COMPASS in $2010$ using a $160\, \rm{GeV}/c$ $\mu^+$ beam and a transversely polarized $NH_3$ target. The asymmetries are extracted as function of Bjorken-$x$, of the total transverse momentum of the oppositely charged hadron pair and of the fraction of available energy $z$ carried by the pair. Indications for positive Collins and Sivers asymmetries are obtained as expected from models.

• Excitations of static isolated fermions in the Higgs phase of gauge Higgs theory

  Kazue Matsuyama, Jeff Greensite

  SciPost Phys. Proc. 6, 012 (2022) · published 31 May 2022 | Toggle abstract · pdf

  A spectrum of localized excitations of isolated static fermions has been discovered in several different gauge Higgs theories. In lattice numerical simulations, we show that the charged elementary particles can have the spectrum of excitations in the Higgs phase of SU(3) gauge Higgs theory, q=2 Abelian Higgs theory, Landau-Ginzburg theory, and in chiral U(1) gauge Higgs theory. Possibly these excited states of the isolated fermions can be observed in ARPES studies of conventional superconductors. Also, we consider that similar kinds of excitations could exist in other gauge Higgs theories, such as the electroweak sector of the Standard Model.

• Intermittency analysis of charged hadrons generated in Pb-Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV and 5.02 TeV

  Salman Khurshid Malik, Ramni Gupta

  SciPost Phys. Proc. 15, 012 (2024) · published 2 April 2024 | Toggle abstract · pdf

  Local density fluctuations are expected to scale as a universal power-law when the system approaches critical point. Such power-law fluctuations are studied within the framework of intermittency through the measurement of normalized factorial moments in ($\eta$, $\phi$) phase space. Observations and results from the intermittency analysis performed for charged particles in Pb-Pb collisions using PYTHIA8/Angantyr at 2.76 TeV and 5.02 TeV are reported. We observe no scaling behaviour in the particle generation for any of the centrality studied in narrow p$_T$ bins. The scaling exponent $\nu$ shows no dependence on the centrality ranges.

• From the XXZ chain to the integrable Rydberg-blockade ladder via non-invertible duality defects

  Luisa Eck, Paul Fendley

  SciPost Phys. 16, 127 (2024) · published 21 May 2024 | Toggle abstract · pdf

  Strongly interacting models often possess "dualities" subtler than a one-to-one mapping of energy levels. The maps can be non-invertible, as apparent in the canonical example of Kramers and Wannier. We analyse an algebraic structure common to the XXZ spin chain and three other models: Rydberg-blockade bosons with one particle per square of a ladder, a three-state antiferromagnet, and two Ising chains coupled in a zigzag fashion. The structure yields non-invertible maps between the four models while also guaranteeing all are integrable. We construct these maps explicitly utilising topological defects coming from fusion categories and the lattice version of the orbifold construction, and use them to give explicit conformal-field-theory partition functions describing their critical regions. The Rydberg and Ising ladders also possess interesting non-invertible symmetries, with the spontaneous breaking of one in the former resulting in an unusual ground-state degeneracy.

• Quantum Monte Carlo simulation of the 3D Ising transition on the fuzzy sphere

  Johannes Stephan Hofmann, Florian Goth, Wei Zhu, Yin-Chen He, Emilie Huffman

  SciPost Phys. Core 7, 028 (2024) · published 9 May 2024 | Toggle abstract · pdf

  We present a numerical quantum Monte Carlo (QMC) method for simulating the 3D phase transition on the recently proposed fuzzy sphere [Phys. Rev. X 13, 021009 (2023)]. By introducing an additional SU(2) layer degree of freedom, we reformulate the model into a form suitable for sign-problem-free QMC simulation. From the finite-size-scaling, we show that this QMC-friendly model undergoes a quantum phase transition belonging to the 3D Ising universality class, and at the critical point we compute the scaling dimensions from the state-operator correspondence, which largely agrees with the prediction from the conformal field theory. These results pave the way to construct sign-problem-free models for QMC simulations on the fuzzy sphere, which could advance the future study on more sophisticated criticalities.

• Topological aspects of brane fields: Solitons and higher-form symmetries

  Salvatore D. Pace, Yu Leon Liu

  SciPost Phys. 16, 128 (2024) · published 21 May 2024 | Toggle abstract · pdf

  In this note, we classify topological solitons of $n$-brane fields, which are nonlocal fields that describe $n$-dimensional extended objects. We consider a class of $n$-brane fields that formally define a homomorphism from the $n$-fold loop space $\Omega^n X_D$ of spacetime $X_D$ to a space $\mathcal{E}_n$. Examples of such $n$-brane fields are Wilson operators in $n$-form gauge theories. The solitons are singularities of the $n$-brane field, and we classify them using the homotopy theory of ${\mathbb{E}_n}$-algebras. We find that the classification of codimension ${k+1}$ topological solitons with ${k≥ n}$ can be understood using homotopy groups of $\mathcal{E}_n$. In particular, they are classified by ${\pi_{k-n}(\mathcal{E}_n)}$ when ${n>1}$ and by ${\pi_{k-n}(\mathcal{E}_n)}$ modulo a ${\pi_{1-n}(\mathcal{E}_n)}$ action when ${n=0}$ or ${1}$. However, for ${n>2}$, their classification goes beyond the homotopy groups of $\mathcal{E}_n$ when ${k< n}$, which we explore through examples. We compare this classification to $n$-form $\mathcal{E}_n$ gauge theory. We then apply this classification and consider an ${n}$-form symmetry described by the abelian group ${G^{(n)}}$ that is spontaneously broken to ${H^{(n)}\subset G^{(n)}}$, for which the order parameter characterizing this symmetry breaking pattern is an ${n}$-brane field with target space ${\mathcal{E}_n = G^{(n)}/H^{(n)}}$. We discuss this classification in the context of many examples, both with and without 't Hooft anomalies.