Publications

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• B-type D-branes in hybrid models

  Johanna Knapp, Robert Pryor

  SciPost Phys. 17, 165 (2024) · published 12 December 2024 | Toggle abstract · pdf

  A hybrid model is a fibration of a Landau-Ginzburg orbifold over a geometric base. We study B-type D-branes in hybrid models. Imposing B-type supersymmetry on the boundary action, we show that D-branes are specified by matrix factorisations in the fibre direction, together with some geometric data associated to the base. We also deduce conditions for the compatibility of these branes with the bulk orbifold actions and R-symmetry. We construct examples of hybrid B-branes which are generalisations of well-studied branes in geometric and Landau-Ginzburg models. Hybrid models can arise at limiting points of the stringy Kähler moduli space of Calabi-Yaus, and can be realised as phases of the corresponding gauged linear sigma models (GLSMs). Using GLSM techniques, we establish connections between geometric branes and hybrid branes. As explicit examples, we consider one- and two-parameter Calabi-Yau hybrids with a $\mathbb{P}^1$-base.

  1 citation

• Codebase release 1.0 for NumDynInflation

  Siddharth S. Bhatt, Swagat S. Mishra, Soumen Basak, Surya N. Sahoo

  SciPost Phys. Codebases 42-r1.0 (2024) · published 12 December 2024 | Toggle abstract · src

  Numerical simulations of the inflationary dynamics are presented here for a single canonical scalar field minimally coupled to gravity. We spell out the basic equations governing the inflationary dynamics in terms of cosmic time $t$ and define a set of dimensionless variables convenient for numerical analysis. We then provide a link to our simple numerical Python code on GitHub that can be used to simulate the background dynamics as well as the evolution of linear perturbations during inflation. The code computes both scalar and tensor power spectra for a given inflaton potential $V(\phi)$. We discuss a concrete algorithm to use the code for various purposes, especially for computing the enhanced scalar power spectrum in the context of Primordial Black Holes and scalar-induced Gravitational Waves. We also compare the efficiency of different variables used in the literature to compute the scalar fluctuations. We intend to extend the framework to simulate the dynamics of a number of different quantities, including the computation of scalar-induced second-order tensor power spectrum in the near future.

  1 citation

• Pairing symmetry and fermion projective symmetry groups

  Xu Yang, Sayak Biswas, Shuangyuan Lu, Mohit Randeria, Yuan-Ming Lu

  SciPost Phys. 17, 161 (2024) · published 10 December 2024 | Toggle abstract · pdf

  The Ginzburg-Landau (GL) theory is very successful in describing the pairing symmetry, a fundamental characterization of the broken symmetries in a paired superfluid or superconductor. However, GL theory does not describe fermionic excitations such as Bogoliubov quasiparticles or Andreev bound states that are directly related to topological properties of the superconductor. In this work, we show that the symmetries of the fermionic excitations are captured by a Projective Symmetry Group (PSG), which is a group extension of the bosonic symmetry group in the superconducting state. We further establish a correspondence between the pairing symmetry and the fermion PSG. When the normal and superconducting states share the same spin rotational symmetry, there is a simpler correspondence between the pairing symmetry and the fermion PSG, which we enumerate for all 32 crystalline point groups. We also discuss the general framework for computing PSGs when the spin rotational symmetry is spontaneously broken in the superconducting state. This PSG formalism leads to experimental consequences, and as an example, we show how a given pairing symmetry dictates the classification of topological superconductivity.

  1 citation

• Cracking hadron and nuclear collisions open with ropes and string shoving in PYTHIA8

  Smita Chakraborty

  SciPost Phys. Proc. 10, 017 (2022) · published 10 August 2022 | Toggle abstract · pdf

  Enhancement in strangeness yields in heavy-ion collisions is regarded as one of the attributes of the Quark-Gluon Plasma (QGP) along with jet quenching and final-state collectivity. To reproduce these effects in the MC implementation of the Lund string model in \pythia, the inclusion of non-perturbative mechanisms like string shoving and rope hadronization is crucial. In this proceeding, we discuss our latest implementation of these mechanisms and the preliminary results for the strangeness enhancement in high-multiplicity p-p, p-Pb and Xe-Xe. We conclude with remarks on the ongoing development of the model.

  1 citation

• Lepton flavor violation at FCC-ee and CEPC

  Pankaj Munbodh

  SciPost Phys. Proc. 17, 006 (2025) · published 23 July 2025 | Toggle abstract · pdf

  Lepton flavor violating processes are highly suppressed in the Standard Model. Therefore, if observed, lepton flavor violation would be a clear indication of new physics beyond the Standard Model. We study the process $e^+e^-\to\tau\mu$ at tree-level in the Standard Model Effective Field Theory both on the $Z$-pole and at higher center-of-mass energies. We show that the constraints derived from the future circular $e^+e^-$ colliders FCC-ee and CEPC, are complementary to those obtained from low-energy tau decays at BaBar and Belle, as well as projections from Belle-II.

  1 citation

• Amplitude and colour evolution

  Simon Plätzer

  SciPost Phys. Proc. 15, 007 (2024) · published 2 April 2024 | Toggle abstract · pdf

  Colour evolution and parton branching at the amplitude level have become important theoretical frameworks to improve parton showers, and are algorithms in their own right: They complement shower development by resummation algorithms capable of including interference effects and subleading colour contributions at an unprecedented level. I summarize recent development in the field, focusing on soft gluon evolution, hadronization, and the CVolver framework.

  1 citation

• Asymptotics of Weil-Petersson volumes and two-dimensional quantum gravities

  Luca Griguolo, Jacopo Papalini, Lorenzo Russo, Domenico Seminara

  SciPost Phys. 17, 156 (2024) · published 6 December 2024 | Toggle abstract · pdf

  We propose a refined expression for the large genus asymptotics of the Weil-Petersson volumes of the moduli space of super-Riemann surfaces with an arbitrary number of boundaries. Our formula leverages the connection between JT supergravity and its matrix model definition, utilizing some basic tools of resurgence theory. The final result holds for arbitrary boundary lengths and preserves the polynomial structure of the super-volumes. As a byproduct we also obtain a prediction for the large genus asymptotics of generalized $\Theta$-class intersection numbers. We extend our proposal to the case of the quantum volumes relevant for the Virasoro minimal string/Liouville gravity. Performing the classical limit on the quantum volumes, we recover a formula for the ordinary Weil-Petersson building blocks of JT gravity.

  1 citation

• Local density of states correlations in the Lévy-Rosenzweig-Porter random matrix ensemble

  Aleksey Lunkin, Konstantin Tikhonov

  SciPost Phys. 19, 015 (2025) · published 16 July 2025 | Toggle abstract · pdf

  We present an analytical calculation of the local density of states correlation function $ \beta(\omega) $ in the Lévy-Rosenzweig-Porter random matrix ensemble at energy scales larger than the level spacing but smaller than the bandwidth. The only relevant energy scale in this limit is the typical level width $\Gamma_0$. We show that $\beta(\omega \ll \Gamma_0) \sim W/\Gamma_0$ (here $W$ is width of the band) whereas $\beta(\omega \gg \Gamma_0) \sim (W/\Gamma_0) (\omega/\Gamma_0)^{-\mu} $ where $\mu$ is an index characterising the distribution of the matrix elements. We also provide an expression for the average return probability at long times: $\ln [R(t\gg\Gamma_0^{-1})] \sim -(\Gamma_0 t)^{\mu/2}$. Numerical results based on the pool method and exact diagonalization are also provided and are in agreement with the analytical theory.

  1 citation

• Tapered amplifier laser with frequency-shifted feedback

  A. Bayerle, S. Tzanova, P. Vlaar, B. Pasquiou, F. Schreck

  SciPost Phys. 1, 002 (2016) · published 22 October 2016 | Toggle abstract · pdf

  We present a frequency-shifted feedback (FSF) laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time. If the FSF laser is seeded by a continuous-wave laser a frequency comb spanning the output spectrum appears in addition to the broadband emission. The laser has an output power of 280mW and a center wavelength of 780nm. The ease and flexibility of use of tapered amplifiers makes our FSF laser attractive for a wide range of applications, especially in metrology.

  1 citation

• BBBW on the spindle

  Antonio Amariti, Salvo Mancani, Davide Morgante, Nicolò Petri, Alessia Segati

  SciPost Phys. 17, 154 (2024) · published 5 December 2024 | Toggle abstract · pdf

  We study the spindle compactification of families of AdS$_5$ consistent truncations corresponding to M5 branes wrapped on complex curves in Calabi-Yau three-folds. From the AdS/CFT correspondence these models are dual to $\mathcal{N}=1$ SCFTs obtained by gluing of $T_N$ blocks. The truncations considered here have both vector and hyper multiplets and the analysis of the BPS equations on the spindle allows to extract the central charges. Such analysis gives also consistency conditions for the existence of the solutions. The solutions are then found both analytically and numerically for opportune choices of the charges for some sub-families of truncations. We then compare our results with the one expected from the field theory side, by integrating the anomaly polynomial.

  1 citation