Publications

Order by: publication date number of citations

• HEJ 2.2: W boson pairs and Higgs boson plus jet production at high energies

  Jeppe R. Andersen, Bertrand Ducloué, Conor Elrick, Hitham Hassan, Andreas Maier, Graeme Nail, Jérémy Paltrinieri, Andreas Papaefstathiou, Jennifer M. Smillie

  SciPost Phys. Codebases 21 (2023) · published 6 December 2023 | Toggle abstract · pdf

  We present version 2.2 of the High Energy Jets (HEJ) Monte Carlo event generator for hadronic scattering processes at high energies. The new version adds support for two further processes of central phenomenological interest, namely the production of a W boson pair with equal charge together with two or more jets and the production of a Higgs boson with at least one jet. Furthermore, a new prediction for charged lepton pair production with high jet multiplicities is provided in the high-energy limit. The accuracy of HEJ 2.2 can be increased further through an enhanced interface to standard predictions based on conventional perturbation theory. We describe all improvements and provide extensive usage examples. HEJ 2.2 can be obtained from https://hej.hepforge.org.

  7 citations

• The inheritance of energy conditions: Revisiting no-go theorems in string compactifications

  Heliudson Bernardo, Suddhasattwa Brahma, Mir Mehedi Faruk

  SciPost Phys. 15, 225 (2023) · published 5 December 2023 | Toggle abstract · pdf

  One of the fundamental challenges in string theory is to derive realistic four-dimensional cosmological backgrounds from it despite strict consistency conditions that constrain its possible low-energy backgrounds. In this work, we focus on energy conditions as covariant and background-independent consistency requirements in order to classify possible backgrounds coming from low-energy string theory in two steps. Firstly, we show how supergravity actions obey many relevant energy conditions under some reasonable assumptions. Remarkably, we find that the energy conditions are satisfied even in the presence of objects which individually violate them due to the tadpole cancellation condition. Thereafter, we list a set of conditions for a higher-dimensional energy condition to imply the corresponding lower-dimensional one, thereby categorizing the allowed low-energy solutions. As for any no-go theorem, our aim is to highlight the assumptions that must be circumvented for deriving four-dimensional spacetimes that necessarily violate these energy conditions, with emphasis on cosmological backgrounds.

  3 citations

• Covariant canonical formulations of classical field theories

  Francois Gieres

  SciPost Phys. Lect. Notes 77 (2023) · published 5 December 2023 | Toggle abstract · pdf

  We review in simple terms the covariant approaches to the canonical formulation of classical relativistic field theories (in particular gauge field theories and general relativity) and we discuss the relationships between these approaches as well as the relation with the standard (non-covariant) Hamiltonian formulation. Particular attention is paid to conservation laws (notably related to geometric symmetries) within the different approaches. Moreover, for each of these approaches, the impact of space-time boundaries is also addressed. To make the text accessible to a wider audience, we have included an outline of Poisson and symplectic geometry for both classical mechanics and field theory.

  6 citations

• Non-supersymmetric AdS from string theory

  Zihni Kaan Baykara, Daniel Robbins, Savdeep Sethi

  SciPost Phys. 15, 224 (2023) · published 4 December 2023 | Toggle abstract · pdf

  We construct non-supersymmetric $AdS_3$ solutions of the $\mathrm O(16)× \mathrm O(16)$ heterotic string. Most of the backgrounds have a classical worldsheet definition but are quantum string vacua in the sense that string loop corrections change the curvature of spacetime. At one-loop, the change in the cosmological constant is positive but never sufficient to uplift to de Sitter space. By computing the spectrum of spacetime scalars, we show that there are no tachyons below the BF bound. We also show that there is a solution with no spacetime NS-NS flux. This background has no classical string limit. Surprisingly, there appears to be parametric control over these constructions, which provide a framework for exploring quantum gravity and holography without supersymmetry.

  12 citations

• Quantum wavefront shaping with a 48-element programmable phase plate for electrons

  Chu-Ping Yu, Francisco Vega Ibañez, Armand Béché, Johan Verbeeck

  SciPost Phys. 15, 223 (2023) · published 4 December 2023 | Toggle abstract · pdf

  We present a 48-element programmable phase plate for coherent electron waves produced by a combination of photolithography and focused ion beam. This brings the highly successful concept of wavefront shaping from light optics into the realm of electron optics and provides an important new degree of freedom to prepare electron quantum states. The phase plate chip is mounted on an aperture rod placed in the C2 plane of a transmission electron microscope operating in the 100-300 kV range. The phase plate's behavior is characterized by a Gerchberg-Saxton algorithm, showing a phase sensitivity of 0.075 rad/mV at 300 kV, with a phase resolution of approximately 3$\cdot$10$^{-3} \pi$. In addition, we provide a brief overview of possible use cases and support it with both simulated and experimental results.

  20 citations

• Spin rotons and supersolids in binary antidipolar condensates

  Wyatt Kirkby, Thomas Bland, Francesca Ferlaino, Russell N. Bisset

  SciPost Phys. Core 6, 084 (2023) · published 4 December 2023 | Toggle abstract · pdf

  We present a theoretical study of a mixture of antidipolar and nondipolar Bose-Einstein condensates confined to an infinite tube. We predict the presence of a spin roton and its associated instability, which triggers a continuous unmodulated-to-supersolid phase transition. We characterize the phase diagram of the binary system, ranging from the quasi-1D to the radial Thomas-Fermi (elongated 3D) regimes. We also present the dynamic formation of supersolids following a quench from the uniform miscible phase, which maintains phase coherence across the system.

  11 citations

• Gauging tensor networks with belief propagation

  Joseph Tindall, Matt Fishman

  SciPost Phys. 15, 222 (2023) · published 1 December 2023 | Toggle abstract · pdf

  Effectively compressing and optimizing tensor networks requires reliable methods for fixing the latent degrees of freedom of the tensors, known as the gauge. Here we introduce a new algorithm for gauging tensor networks using belief propagation, a method that was originally formulated for performing statistical inference on graphical models and has recently found applications in tensor network algorithms. We show that this method is closely related to known tensor network gauging methods. It has the practical advantage, however, that existing belief propagation implementations can be repurposed for tensor network gauging, and that belief propagation is a very simple algorithm based on just tensor contractions so it can be easier to implement, optimize, and generalize. We present numerical evidence and scaling arguments that this algorithm is faster than existing gauging algorithms, demonstrating its usage on structured, unstructured, and infinite tensor networks. Additionally, we apply this method to improve the accuracy of the widely used simple update gate evolution algorithm.

  21 citations

• Quantum chaos in a harmonic waveguide with scatterers

  Vladimir Alexander Yurovsky

  SciPost Phys. 15, 221 (2023) · published 1 December 2023 | Toggle abstract · pdf

  A set of zero-range scatterers along its axis lifts the integrability of a harmonic waveguide. Effective solution of the Schrödinger equation for this model is possible due to the separable nature of the scatterers and millions of eigenstates can be calculated using modest computational resources. Integrability-chaos transition can be explored as the model chaoticity increases with the number of scatterers and their strengths. The regime of complete quantum chaos and eigenstate thermalization can be approached with 32 scatterers. This is confirmed by properties of energy spectra, the inverse participation ratio, and fluctuations of observable expectation values.

• An association sequence suitable for producing ground-state RbCs molecules in optical lattices

  Arpita Das, Philip D. Gregory, Tetsu Takekoshi, Luke Fernley, Manuele Landini, Jeremy M. Hutson, Simon L. Cornish, Hanns-Christoph Nägerl

  SciPost Phys. 15, 220 (2023) · published 1 December 2023 | Toggle abstract · pdf

  We identify a route for the production of $^{87}$Rb$^{133}$Cs molecules in the $X^1\Sigma^+$ rovibronic ground state that is compatible with efficient mixing of the atoms in optical lattices. We first construct a model for the excited-state structure using constants found by fitting to spectroscopy of the relevant $a\,^3 \Sigma^+ → b\, ^3\Pi_1$ transitions at 181.5 G and 217.1 G. We then compare the predicted transition dipole moments from this model to those found for the transitions that have been successfully used for STIRAP at 181.5 G. We form molecules by magnetoassociation on a broad interspecies Feshbach resonance at 352.7 G and explore the pattern of Feshbach states near 305 G. This allows us to navigate to a suitable initial state for STIRAP by jumping across an avoided crossing with radiofrequency radiation. We identify suitable transitions for STIRAP at 305 G. We characterize these transitions experimentally and demonstrate STIRAP to a single hyperfine level of the ground state with a one-way efficiency of 85(4)%.

  5 citations

• Dynamical mean field theory for models of confluent tissues and beyond

  Persia Jana Kamali, Pierfrancesco Urbani

  SciPost Phys. 15, 219 (2023) · published 30 November 2023 | Toggle abstract · pdf

  We consider a recently proposed model to understand the rigidity transition in confluent tissues and we derive the dynamical mean field theory (DMFT) equations that describes several types of dynamics of the model in the thermodynamic limit: gradient descent, thermal Langevin noise and active drive. In particular we focus on gradient descent dynamics and we integrate numerically the corresponding DMFT equations. In this case we show that gradient descent is blind to the zero temperature replica symmetry breaking (RSB) transition point. This means that, even if the Gibbs measure in the zero temperature limit displays RSB, this algorithm is able to find its way to a zero energy configuration. We include a discussion on possible extensions of the DMFT derivation to study problems rooted in high-dimensional regression and optimization via the square loss function.

  5 citations