Publications

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Thermoelectric coefficients and the figure of merit for large open quantum dots

Robert S. Whitney, Keiji Saito

SciPost Phys. 6, 012 (2019) · published 24 January 2019 | · pdf

We consider the thermoelectric response of chaotic or disordered quantum dots in the limit of phase-coherent transport, statistically described by random matrix theory. We calculate the full distribution of the thermoelectric coefficients (Seebeck $S$ and Peltier $\Pi$), and the thermoelectric figure of merit $ZT$, for large open dots at arbitrary temperature and external magnetic field, when the number of modes in the left and right leads ($N_{\rm L}$ and $N_{\rm R}$) are large. Our results show that the thermoelectric coefficients and $ZT$ are maximal when the temperature is half the Thouless energy, and the magnetic field is negligible. They remain small, even at their maximum, but they exhibit a type of universality at all temperatures, in which they do not depend on the asymmetry between the left and right leads $(N_{\rm L}-N_{\rm R})$, even though they depend on $(N_{\rm L}+N_{\rm R})$.
ATLAS LAr Calorimeter commissioning for LHC Run-3

Luka Selem

SciPost Phys. Proc. 8, 157 (2022) · published 14 July 2022 | · pdf

The ATLAS experiment at the Large Hadron Collider (LHC) measures proton--proton collisions at high energies. Within the Phase-I upgrade of the LHC before the start of Run-3 in 2022, the trigger system of the Liquid Argon calorimeter of ATLAS is being prepared to cope with an increased number of simultaneous proton--proton collisions. In the back-end of this new trigger system, the LATOME boards will be responsible for the computation of the energies deposited in the calorimeter. The commissioning of this computation within the LATOME is presented.
Applying Quantum Tomography to Hadronic Interactions

J. C. Martens, J. P. Ralston, D. Tapia Takaki

SciPost Phys. Proc. 8, 154 (2022) · published 14 July 2022 | · pdf

A proper description of inclusive reactions is expressed with density matrices. Quantum tomography reconstructs density matrices from experimental observables. We review recent work that applies quantum tomography to practical experimental data analysis. Almost all field-theoretic formalism and modeling used in a traditional approach is circumvented with great efficiency. Tomographically-determined density matrices can express information about quantum systems which cannot in principle be expressed with distributions defined by classical probability. Topics such as entanglement and von Neumann entropy can be accessed using the same natural language where they are defined. A deep relation exists between {\it separability}, as defined in quantum information science, and {\it factorization}, as defined in high energyphysics. Factorization acquires a non-perturbative definition when expressed in terms of a conditional form of separability. An example illustrates how to go from data for momentum 4-vectors to a density matrix while bypassing almost all the formalism of the Standard Model.
An algebraic approach to intertwined quantum phase transitions in the Zr isotopes

Noam Gavrielov

SciPost Phys. Proc. 14, 028 (2023) · published 24 November 2023 | · pdf

The algebraic framework of the interacting boson model with configuration mixing is employed to demonstrate the occurrence of intertwined quantum phase transitions (IQPTs) in the $_{40}$Zr isotopes with neutron number 52-70. The detailed quantum and classical analyses reveal a QPT of crossing normal and intruder configurations superimposed on a QPT of the intruder configuration from U(5) to SU(3) and a crossover from SU(3) to SO(6) dynamical symmetries.
Topological insulators and geometry of vector bundles

Alexander S. Sergeev

SciPost Phys. Lect. Notes 67 (2023) · published 12 April 2023 | · pdf

For a long time, band theory of solids has focused on the energy spectrum, or Hamiltonian eigenvalues. Recently, it was realized that the collection of eigenvectors also contains important physical information. The local geometry of eigenspaces determines the electric polarization, while their global twisting gives rise to the metallic surface states in topological insulators. These phenomena are central topics of the present notes. The shape of eigenspaces is also responsible for many intriguing physical analogies, which have their roots in the theory of vector bundles. We give an informal introduction to the geometry and topology of vector bundles and describe various physical models from this mathematical perspective.
Transverse spin asymmetries for inclusive $\rho^0$ production in SIDIS at COMPASS

A. Kerbizi

SciPost Phys. Proc. 8, 146 (2022) · published 14 July 2022 | · 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.
Spatial separation of spin currents in transition metal dichalcogenides

Antonio L. R. Manesco, Artem Pulkin

SciPost Phys. Core 6, 036 (2023) · published 1 May 2023 | · pdf

We theoretically predict spatial separation of spin-polarized ballistic currents in transition metal dichalcogenides (TMDs) due to trigonal warping. We quantify the effect in terms of spin polarization of charge carrier currents in a prototypical 3-terminal ballistic device where spin-up and spin-down charge carriers are collected by different leads. We show that the magnitude of the current spin polarization depends strongly on the charge carrier energy and the direction with respect to crystallographic orientations in the device. We study the (negative) effect of lattice imperfections and disorder on the observed spin polarization. Our investigation provides an avenue towards observing spin discrimination in a defect-free time reversal-invariant material.
Mixed permutation symmetry quantum phase transitions of critical three-level atom models

Alberto Mayorgas, J. Guerrero, Manuel Calixto

SciPost Phys. Proc. 14, 036 (2023) · published 24 November 2023 | · pdf

We define the concept of Mixed Symmetry Quantum Phase Transition (MSQPT), considering each permutation symmetry sector $\mu$ of an identical particles system, as singularities in the properties of the lowest-energy state into each $\mu$ when shifting a Hamiltonian control parameter $\lambda$. A three-level Lipkin-Meshkov-Glick (LMG) model is chosen to typify our construction. Firstly, we analyze the finite number $N$ of particles case, proving the presence of MSQPT precursors. Then, in the thermodynamic limit $N\to∞$, we calculate the lowest-energy density inside each sector $\mu$, augmenting the control parameter space by $\mu$, and showing a phase diagram with four different quantum phases.
Dark Matter phenomenology in 2HDMS

Gudrid Moortgat-Pick, Juhi Dutta, Cheng Li, Merle Schreiber, Sheikh F. Tabira, Julia Ziegler

SciPost Phys. Proc. 12, 072 (2023) · published 6 September 2023 | · pdf

The constituents of dark matter are still an unresolved puzzle. Several Beyond Standard Model (BSM) Physics offer suitable candidates. In this study here we consider the Two Higgs Doublet model augmented with a complex scalar singlet (2HDMS) and focus on the dark matter phenomenology of 2HDMS with the complex scalar singlet as the dark matter candidate. The parameter space allowed from existing experimental constraints from dark matter, flavour physics and collider searches has been studied. The discovery potential for such a 2HDMS at HL-LHC and at future $e^+e^-$ colliders has been worked out.
STEP: A tool to perform tests of smoothness on differential distributions based on expansion of polynomials

Patrick L. S. Connor, Radek Žlebčík

SciPost Phys. Core 6, 040 (2023) · published 1 June 2023 | · pdf

We motivate and describe a method based on fits with polynomials to test the smoothness of differential distributions. As a demonstration, we apply the method to several measurements of inclusive jet double-differential cross section in the jet transverse momentum and rapidity at the Tevatron and LHC. This method opens new possibilities to test the quality of differential distributions used for the extraction of physics quantities such as the strong coupling.

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