Publications

Order by: publication date number of citations

• The tower of Kontsevich deformations for Nambu-Poisson structures on $\mathbb{R}^d$: Dimension-specific micro-graph calculus

  Ricardo Buring, Arthemy V. Kiselev

  SciPost Phys. Proc. 14, 020 (2023) · published 23 November 2023 | Toggle abstract · pdf

  In Kontsevich's graph calculus, internal vertices of directed graphs are inhabited by multi - vectors, e.g., Poisson bi - vectors; the Nambu - determinant Poisson brackets are differential - polynomial in the Casimir(s) and density $\varrho$ times Levi - Civita symbol. We resolve the old vertices into subgraphs such that every new internal vertex contains one Casimir or one Levi - Civita symbol×$\varrho$. Using this micro - graph calculus, we show that Kontsevich's tetrahedral $\gamma_3$-flow on the space of Nambu - determinant Poisson brackets over $\mathbb{R}^3$ is a Poisson coboundary: we realize the trivializing vector field $\vec{X}$ over $\mathbb{R}^3$ using micro - graphs. This $\vec{X}$ projects to the known trivializing vector field for the $\gamma_3$-flow over $\mathbb{R}^2$.

• Probing hadronic interaction models with the hybrid data of the Pierre Auger Observatory

  Jakub Vícha for the Pierre Auger Collaboration

  SciPost Phys. Proc. 13, 026 (2023) · published 29 September 2023 | Toggle abstract · pdf

  Presently large systematic uncertainties remain in the description of hadronic interactions at ultra-high energies and a fully consistent description of air-shower experimental data is yet to be reached. The amount of data collected by the Pierre Auger Observatory using simultaneously the fluorescence and surface detectors in the energy range 10$^{18.5}$ -10$^{19.0}$ eV has provided opportunity to perform a multi-parameter test of model predictions. We apply a global method to simultaneously fit the mass composition of cosmic rays and adjustments to the simulated depth of shower maximum, and hadronic signal at ground level. The best description of the hybrid data is obtained for a deeper scale of simulated depth of shower maximum than predicted by hadronic interaction models tuned to the LHC data. Consequently, the deficit of the simulated hadronic signal at ground level, dominated by muons, is alleviated with respect to the unmodified hadronic interaction models. Because of the size of the adjustments to simulated depth of shower maximum and hadronic signal and the large number of events in the sample, the statistical significance of these assumed adjustments is large, greater than 5$\sigma_{stat}$, even for the combination of the systematic experimental shifts within 1$\sigma_{sys}$ that are the most favorable for the models.

• Studying mass generation for gluons

  Gernot Eichmann, Jan M. Pawlowski

  SciPost Phys. Proc. 6, 018 (2022) · published 31 May 2022 | Toggle abstract · pdf

  In covariant gauges, the gluonic mass gap in Yang-Mills theory manifests itself in the basic observation that the massless pole in the perturbative gluon propagator disappears in nonperturbative calculations, but the origin of this behavior is not yet fully understood. We summarize a recent study of the respective dynamics with Dyson-Schwinger equations in Landau-gauge Yang-Mills theory. We identify the parameter that distinguishes the massive Yang-Mills regime from the massless decoupling solutions, whose endpoint is the scaling solution. Similar to the PT-BFM scheme, we find evidence that mass generation in the transverse sector is triggered by longitudinal massless poles.

• Position operators and interband matrix elements of scalar and vector potentials in the 8-band Kane model

  I. A. Ado, M. Titov, Rembert A. Duine, Arne Brataas

  SciPost Phys. 17, 009 (2024) · published 10 July 2024 | Toggle abstract · pdf

  We diagonalize the 8-band Kane Hamiltonian with a proper inclusion of the interband matrix elements of the scalar and vector potentials. This leads, among other results, to a modification of the conventional expression for the spin-orbit coupling (SOC) strength in narrow-gap semiconductors with the zinc blende symmetry. We find that in GaAs, at low temperatures, the correct expression for the SOC strength is actually twice as large as usually considered. In InSb it is $1.76$ times larger. We also provide a proper treatment of the interband matrix elements of the position operator. We show that the velocity operator in a crystal should be defined as a time-derivative of a fictitious position operator rather than the physical one. We compute the expressions for both these position operators projected to the conduction band of the 8-band Kane model. We also derive an expression for the projected velocity operator and demonstrate that the SOC strength in it differs from the SOC strength in the Hamiltonian. The ratio between them is not equal to $1$, as it is often assumed for the Rashba model. It does not equal $2$ either. The correct result for this ratio is given by a rational function of the parameters of the model. This function takes values between $4(23+3\sqrt{2})/73≈ 1.49$ and $2$. Our findings modify a vast number of research results obtained using the Rashba model and provide a path for consistent treatment of the latter in future applications.

• Computation of entanglement entropy in inhomogeneous free fermions chains by algebraic Bethe ansatz

  Pierre-Antoine Bernard, Gauvain Carcone, Nicolas Crampé, Luc Vinet

  SciPost Phys. Proc. 14, 018 (2023) · published 23 November 2023 | Toggle abstract · pdf

  The computation of the entanglement entropy for inhomogeneous free fermions chains based on $q$-Racah polynomials is considered. The eigenvalues of the truncated correlation matrix are obtained from the diagonalization of the associated Heun operator via the algebraic Bethe Ansatz. In the special case of chains based on dual $q$-Hahn polynomials, the eigenvectors and eigenvalues are expressed in terms of symmetric polynomials evaluated on the Bethe roots.

• New developments in KKMChh: Quark-level exponentiated radiative corrections and semi-analytical results

  S.A. Yost, M. Dittrich, S. Jadach, B.F.L. Ward, Z. Wąs

  SciPost Phys. Proc. 7, 016 (2022) · published 20 June 2022 | Toggle abstract · pdf

  We describe a new semi-analytical program, KKhhFoam, which provides a simplified framework for testing the amplitude-level exponentiation scheme (CEEX) of the full KKMChh program in the semi-soft limit. The structure of the KKhhFoam integrand is also helpful for elucidating the structure of CEEX. We also discuss the representation of ISR in KKMChh and compare the ISR added by KKMChh to the effect of switching to a QED-corrected PDF, at the individual quark level, and suggest a new approach to running KKMChh with QED-corrected PDFs.

• NLO collinear factorization of large mass diphoton photoproduction amplitude

  Oskar Grocholski, Bernard Pire, Paweł Sznajder, Lech Szymanowski, Jakub Wagner

  SciPost Phys. Proc. 8, 078 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We calculate large mass diphoton exclusive photoproduction in the framework of collinear QCD factorization at next to leading order in {\alpha}s and at leading twist. Collinear divergences of the coefficient function are absorbed by the evolution of the generalized parton distributions (GPDs). This result enlarges the existing factorization proofs to 2 -> 3 processes, opening new reactions to a trustable extraction of GPDs.

• Measurement of the $\textit{CP}$ structure of the Higgs-tau Yukawa coupling

  Vinaya Krishnan MB

  SciPost Phys. Proc. 8, 008 (2022) · published 11 July 2022 | Toggle abstract · pdf

  The CMS experiment at the LHC has performed the first measurement of the CP structure of the Yukawa coupling between the Higgs boson and tau leptons. The measurement is based on data collected in proton-proton collisions at $\sqrt{s} = 13$ TeV during 2016-18, corresponding to an integrated luminosity of $137\text{ fb}^{-1}$. The analysis utilizes the angular correlation between the decay planes of tau leptons produced in Higgs boson decays, where dedicated analysis techniques are used to optimise the reconstruction of tau decay planes. The measured value of the CP mixing angle is $4\pm17^{\circ}$, at $68\%$ confidence level. The pure $\textit{CP-}$odd hypothesis is excluded by $3.2$ standard deviations. The analysis strategies and the results of the measurement are presented.

• Josephson effects between the Kitaev ladder superconductors

  Osamu Kanehira, Hiroki Tsuchiura

  SciPost Phys. Proc. 11, 014 (2023) · published 6 June 2023 | Toggle abstract · pdf

  The two-leg ladder system consisting of the Kitaev chains is known to exhibit a richer phase diagram than that of the single chain. We theoretically investigate the variety of the Josephson effects between the ladder systems. We consider the Josephson phase difference $\theta$ between these two ladder systems as well as the phase difference $\phi$ between the parallel chains in each ladder system. The total energy of the junction at $T = 0$ is calculated by a numerical diagonalization method as functions of $\theta$, $\phi$, and also a transverse hopping $t_{\perp}$ in the ladders. We find that, by controlling $t_{\perp}$ and $\phi$, the junction exhibits not only the fractional Josephson effect for the phase difference $\theta$, but also the usual 0-junction and even $\pi$-junction properties.

• Thermodynamics of adiabatic quantum pumping in quantum dots

  Daniele Nello, Alessandro Silva

  SciPost Phys. Core 7, 067 (2024) · published 4 October 2024 | Toggle abstract · pdf

  We consider adiabatic quantum pumping through a resonant level model, a single-level quantum dot connected to two fermionic leads. Using the tools of adiabatic expansion, we develop a self-contained thermodynamic description of this model accounting for the variation of the energy level of the dot and the tunnelling rates with the thermal baths. This enables us to study various examples of pumping cycles computing the relevant thermodynamic quantities, such as the entropy produced and the dissipated power. These quantities are compared with the transport properties of the system, i.e. the pumped charge and the charge noise. Among other results, we find that the entropy production rate vanishes in the charge quantization limit while the dissipated power is quantized in the same limit.