Publications (68)
Multi-reference many-body perturbation theory for nuclei II -- Ab initio study of neon isotopes via PGCM and IM-NCSM calculations
Mikael Frosini, Thomas Duguet, Jean-Paul Ebran +5
The neon isotopic chain displays a rich phenomenology, ranging from clustering in the ground-state of the self-conjugate doubly open-shell stable Ne isotope to the physics o…
Open-Shell Nuclei and Excited States from Multi-Reference Normal-Ordered Hamiltonians
Eskendr Gebrerufael, Angelo Calci, Robert Roth
We discuss the approximate inclusion of three-nucleon interactions into ab initio nuclear structure calculations using a multi-reference formulation of normal ordering and Wick's t…
Nuclear Structure in the Framework of the Unitary Correlation Operator Method
Robert Roth, Thomas Neff, Hans Feldmeier
Correlations play a crucial role in the nuclear many-body problem. We give an overview of recent developments in nuclear structure theory aiming at the description of these interac…
Seeds for Generalized Taxicab Numbers
Jeffrey. H. Dinitz, Richard Games, Robert Roth
The generalized taxicab number is equal to the smallest number that is the sum of positive th powers in ways. This definition is inspired by Ramanujan's obser…
High-Precision Ab Initio Radius Calculations of Boron Isotopes
Tobias Wolfgruber, Tobias Gesser, Marco Knöll +2
We perform a precision study of radii in Boron isotopes for multiple realistic interactions from chiral effective field theory. We obtain predictions of radii with combined many-bo…
Ab initio description of monopole resonances in light- and medium-mass nuclei: I. Technical aspects and uncertainties of ab initio PGCM calculations
Andrea Porro, Thomas Duguet, Jean-Paul Ebran +3
Giant resonances (GRs) are a striking manifestation of collective motions in mesoscopic systems such as atomic nuclei. Until recently, theoretical investigations have essentially r…
Extension of coupled-cluster theory with a non-iterative treatment of connected triply excited clusters to three-body Hamiltonians
Sven Binder, Piotr Piecuch, Angelo Calci +3
We generalize the coupled-cluster (CC) approach with singles, doubles, and the non-iterative treatment of triples termed CCSD(T) to Hamiltonians containing three-body interacti…
Induced Hyperon-Nucleon-Nucleon Interactions and the Hyperon Puzzle
Roland Wirth, Robert Roth
We present the first ab initio calculations for -shell hypernuclei including hyperon-nucleon-nucleon (YNN) contributions induced by a Similarity Renormalization Group transforma…
Ab Initio Description of p-Shell Hypernuclei
Roland Wirth, Daniel Gazda, Petr Navrátil +3
We present the first ab initio calculations for p-shell single-Lambda hypernuclei. For the solution of the many-baryon problem, we develop two variants of the no-core shell model w…
Anisotropic flow in fixed-target Pb+Ne collisions as a probe of quark-gluon plasma
Giuliano Giacalone, Wenbin Zhao, Benjamin Bally +19
The System for Measuring Overlap with Gas (SMOG2) at the LHCb detector enables the study of fixed-target ion-ion collisions at relativistic energies ( GeV…
The unexpected uses of a bowling pin: exploiting Ne isotopes for precision characterizations of collectivity in small systems
Giuliano Giacalone, Benjamin Bally, Govert Nijs +16
Whether or not femto-scale droplets of quark-gluon plasma (QGP) are formed in so-called small systems at high-energy colliders is a pressing question in the phenomenology of the st…
Machine Learning for the Prediction of Converged Energies from Ab Initio Nuclear Structure Calculations
Marco Knöll, Tobias Wolfgruber, Marc L. Agel +2
The prediction of nuclear observables beyond the finite model spaces that are accessible through modern ab initio methods, such as the no-core shell model, pose a challenging task…
Bogoliubov Many-Body Perturbation Theory for Open-Shell Nuclei
Alexander Tichai, Pierre Arthuis, Thomas Duguet +3
A novel Rayleigh-Schrödinger many-body perturbation theory (MBPT) approach is introduced by making use of a particle-number-breaking Bogoliubov reference state to tackle (near-)de…
Light Neutron-Rich Hypernuclei from the Importance-Truncated No-Core Shell Model
Roland Wirth, Robert Roth
We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains --- from He to H…
Polarization rotation in a ferroelectric BaTiO film through low-energy He-implantation
Andreas Herklotz, Robert Roth, Zhi Xiang Chong +6
Domain engineering in ferroelectric thin films is crucial for next-generation microelectronic and photonic technologies. Here, a method is demonstrated to precisely control domain…
Importance-Truncated Large-Scale Shell Model
Christina Stumpf, Jonas Braun, Robert Roth
We propose an importance-truncation scheme for the large-scale nuclear shell model that extends its range of applicability to larger valence spaces and mid-shell nuclei. It is base…
Multi-reference many-body perturbation theory for nuclei III -- Ab initio calculations at second order in PGCM-PT
Mikael Frosini, Thomas Duguet, Jean-Paul Ebran +6
In spite of missing dynamical correlations, the projected generator coordinate method (PGCM) was recently shown to be a suitable method to tackle the low-lying spectroscopy of comp…
No-Core Shell Model Analysis of Light Nuclei
Sofia Quaglioni, Petr Navratil, Guillaume Hupin +3
The fundamental description of both structural properties and reactions of light nuclei in terms of constituent protons and neutrons interacting through nucleon-nucleon and three-n…
Bogoliubov approach to superfluidity of atoms in an optical lattice
Ana Maria Rey, Keith Burnett, Robert Roth +3
We use the Bogoliubov theory of atoms in an optical lattice to study the approach to the Mott-insulator transition. We derive an explicit expression for the superfluid density base…
Similarity renormalization group evolution of hypernuclear Hamiltonians
Roland Wirth, Robert Roth
Unitary transformations of a Hamiltonian generally induce interaction terms beyond the particle rank present in the untransformed Hamiltonian that have to be captured and included…
Progress on Light-Ion Fusion Reactions with Three-Nucleon Forces
Guillaume Hupin, Sofia Quaglioni, Joachim Langhammer +3
The description of structural and dynamical properties of nuclei starting from the fundamental interaction between nucleons has been a long-standing goal in nuclear physics. The ab…
Family of Chiral Two- plus Three-Nucleon Interactions for Accurate Nuclear Structure Studies
Thomas Hüther, Klaus Vobig, Kai Hebeler +2
We present a family of nucleon-nucleon (NN) plus three-nucleon (3N) interactions up to N3LO in the chiral expansion that provides an accurate ab initio description of ground-state…
Hypernuclear No-Core Shell Model
Roland Wirth, Daniel Gazda, Petr Navrátil +1
We extend the No-Core Shell Model (NCSM) methodology to incorporate strangeness degrees of freedom and apply it to single- hypernuclei. After discussing the transformation of t…
Ab Initio Theory of Light-ion Reactions
Petr Navratil, Sofia Quaglioni, Robert Roth
The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear…
Machine Learning for Correlations of Electromagnetic Properties in Ab Initio Calculations
Marco Knöll, Marc L. Agel, Tobias Wolfgruber +2
In ab initio nuclear structure theory, accurately predicting electromagnetic observables, such as moments and transition rates, is essential for a comprehensive understanding of nu…
Accelerating Ab Initio Nuclear Physics Calculations with GPUs
Hugh Potter, Dossay Oryspayev, Pieter Maris +8
This paper describes some applications of GPU acceleration in ab initio nuclear structure calculations. Specifically, we discuss GPU acceleration of the software package MFDn, a pa…
Ab Initio Path to Heavy Nuclei
Sven Binder, Joachim Langhammer, Angelo Calci +1
We present the first ab initio calculations of nuclear ground states up into the domain of heavy nuclei, spanning the range from 16-O to 132-Sn based on two- plus three-nucleon int…
Scattering of light nuclei
Sofia Quaglioni, Petr Navrátil, Robert Roth
The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear…
Center-of-mass problem in truncated configuration interaction and coupled-cluster calculations
Robert Roth, Jeffrey R. Gour, Piotr Piecuch
The problem of center-of-mass (CM) contaminations in ab initio nuclear structure calculations using configuration interaction (CI) and coupled-cluster (CC) approaches is analyzed.…
Halo Structures in p-Shell Hypernuclei with Natural Orbitals
Marco Knöll, Robert Roth
We extend the concept of natural orbitals as an optimized single-particle basis for ab initio nuclear many-body calculations to hypernuclei and show that their superior properties,…
TrES-1 b: A Case Study in Detecting Secular Evolution of Exoplanet Orbits
Simone R. Hagey, Billy Edwards, Angelos Tsiaras +43
We present a comprehensive analysis of transit, eclipse, and radial velocity data of the hot Jupiter TrES-1 b and confirm evidence of orbital variations on secular timescales. Appa…
Structure and stability of trapped atomic boson-fermion mixtures
Robert Roth
The structure of binary mixtures of bosonic and fermionic atoms in an external trapping potential at zero temperature is studied on the basis of a modified Gross-Pitaevskii equatio…
Can Ab Initio Theory Explain the Phenomenon of Parity Inversion in Be?
Angelo Calci, Petr Navrátil, Robert Roth +3
The weakly bound exotic Be nucleus, famous for its ground-state parity inversion and distinct n+ Be halo structure, is investigated from first principles using ch…
No-Core MCSM calculation for Be and Be low-lying spectra
Lang Liu, Takaharu Otsuka, Noritaka Shimizu +2
The low-lying excited states of Be and Be are investigated within a no-core Monte Carlo Shell Model (MCSM) framework employing a realistic potential obtained via the…
Many-body perturbation theories for finite nuclei
Alexander Tichai, Robert Roth, Thomas Duguet
In recent years many-body perturbation theory encountered a renaissance in the field of ab initio nuclear structure theory. In various applications it was shown that perturbation t…
Pade-resummed high-order perturbation theory for nuclear structure calculations
Robert Roth, Joachim Langhammer
We apply high-order many-body perturbation theory for the calculation of ground-state energies of closed-shell nuclei using realistic nuclear interactions. Using a simple recursive…
Spectra of Open-Shell Nuclei with Padé-Resummed Degenerate Perturbation Theory
Joachim Langhammer, Robert Roth, Christina Stumpf
We apply degenerate many-body perturbation theory at high orders for the ab-initio description of ground states and excitation spectra of open-shell nuclei using soft realistic nuc…
Sensitivities and correlations of nuclear structure observables emerging from chiral interactions
Angelo Calci, Robert Roth
Starting from a set of different two- and three-nucleon interactions from chiral effective field theory, we use the importance-truncated no-core shell model for ab initio calculati…
Ab Initio Description of Open-Shell Nuclei: Merging No-Core Shell Model and In-Medium Similarity Renormalization Group
Eskendr Gebrerufael, Klaus Vobig, Heiko Hergert +1
We merge two successful ab initio nuclear-structure methods, the no-core shell model (NCSM) and the multi-reference in-medium similarity renormalization group (IM-SRG) to define a…
Ab Initio No Core Shell Model - Recent Results and Further Prospects
James P. Vary, Pieter Maris, Hugh Potter +14
There has been significant recent progress in solving the long-standing problems of how nuclear shell structure and collective motion emerge from underlying microscopic inter-nucle…
Phase Diagram of Bosons in Two-Color Superlattices from Experimental Parameters
Felix Schmitt, Markus Hild, Robert Roth
We study the zero-temperature phase diagram of a gas of bosonic 87-Rb atoms in two-color superlattice potentials starting directly from the experimental parameters, such as wavelen…
The Ethics of AI-Generated Maps: A Study of DALLE 2 and Implications for Cartography
Yuhao Kang, Qianheng Zhang, Robert Roth
The rapid advancement of artificial intelligence (AI) such as the emergence of large language models including ChatGPT and DALLE 2 has brought both opportunities for improving prod…
Ab initio description of monopole resonances in light- and medium-mass nuclei: IV. Angular momentum projection and rotation-vibration coupling
Andrea Porro, Thomas Duguet, Jean-Paul Ebran +3
Giant Resonances are, with nuclear rotations, the most evident expression of collectivity in finite nuclei. These two categories of excitations, however, are traditionally describe…
Systematics of 2+ states in C isotopes from the ab initio no-core shell model
Christian Forssén, Robert Roth, Petr Navrátil
We study low-lying states of even carbon isotopes in the range A = 10 - 20 within the large- scale no-core shell model (NCSM). Using several accurate nucleon-nucleon (NN) as well a…
Ab-initio phase diagram of ultracold 87-Rb in an one-dimensional two-color superlattice
Felix Schmitt, Markus Hild, Robert Roth
We investigate the ab-initio phase diagram of ultracold 87-Rb atoms in an one-dimensional two-color superlattice. Using single-particle band structure calculations we map the exper…
Ab initio many-body calculations of nucleon-4He scattering with three-nucleon forces
Guillaume Hupin, Joachim Langhammer, Petr Navrátil +3
We extend the ab initio no-core shell model/resonating-group method to include three-nucleon (3N) interactions for the description of nucleon-nucleus collisions. We outline the for…
Similarity-Transformed Chiral NN+3N Interactions for the Ab Initio Description of 12-C and 16-O
Robert Roth, Joachim Langhammer, Angelo Calci +2
We present first ab initio no-core shell model (NCSM) calculations using similarity renormalization group (SRG) transformed chiral two-nucleon (NN) plus three-nucleon (3N) interact…
Ab initio many-body calculations of nucleon scattering on 4He, 7Li, 7Be, 12C and 16O
Petr Navratil, Robert Roth, Sofia Quaglioni
We combine a recently developed ab initio many-body approach capable of describing simultaneously both bound and scattering states, the ab initio NCSM/RGM, with an importance trunc…
The nuclear charge radius of
Patrick Müller, Matthias Heinz, Phillip Imgram +6
The size is a key property of a nucleus. Accurate nuclear radii are extracted from elastic electron scattering, laser spectroscopy, and muonic atom spectroscopy. The results are no…
Importance Truncation for Large-Scale Configuration Interaction Approaches
Robert Roth
We introduce an iterative importance truncation scheme which aims at reducing the dimension of the model space of configuration interaction approaches by an a priori selection of t…
Collective excitations in deformed sd-shell nuclei from realistic interactions
Bastian Erler, Robert Roth
Background: Collective excitations of nuclei and their theoretical descriptions provide an insight into the structure of nuclei. Replacing traditional phenomenological interactions…
Ab initio description of monopole resonances in light- and medium-mass nuclei: II. Ab initio PGCM calculations in Ti, Si and Mg
Andrea Porro, Thomas Duguet, Jean-Paul Ebran +3
Giant resonances (GRs) are a striking manifestation of collective motions in atomic nuclei. The present paper is the second in a series of four dedicated to the use of the projecte…
Ab initio description of monopole resonances in light- and medium-mass nuclei: III. Moments evaluation in ab initio PGCM calculations
Andrea Porro, Thomas Duguet, Jean-Paul Ebran +3
The paper is the third of a series dedicated to the ab initio description of monopole giant resonances in mid-mass closed- and open-shell nuclei via the so-called projected generat…
Ultracold Bose gases in time-dependent 1D superlattices: response and quasimomentum structure
Markus Hild, Felix Schmitt, Ilona Türschmann +1
The response of ultracold atomic Bose gases in time-dependent optical lattices is discussed based on direct simulations of the time-evolution of the many-body state in the framewor…
Open-Shell Nuclei from No-Core Shell Model with Perturbative Improvement
Alexander Tichai, Eskendr Gebrerufael, Klaus Vobig +1
We introduce a hybrid many-body approach that combines the flexibility of the No-Core Shell Model (NCSM) with the efficiency of Multi-Configurational Perturbation Theory (MCPT) to…
Nuclear Structure - "ab initio"
Hans Feldmeier, Thomas Neff, Robert Roth
An ab-initio description of atomic nuclei that solves the nuclear many-body problem for realistic nuclear forces is expected to possess a high degree of predictive power. In this c…
Hyperon-Nucleon Interaction Constrained by Light Hypernuclei
Marco Knöll, Robert Roth
Ab initio structure calculations for p-shell hypernuclei have recently become accessible through extensions of nuclear many-body methods, such as the no-core shell model, in combin…
Natural orbitals for ab initio no-core shell model calculations
Alexander Tichai, Julius Müller, Klaus Vobig +1
We explore the impact of optimizations of the single-particle basis on the convergence behavior and robustness of ab initio no-core shell model calculations. Our focus is on novel…
Electromagnetic Strength Distributions from the Ab Initio No-Core Shell Model
Christina Stumpf, Tobias Wolfgruber, Robert Roth
We present an ab initio approach for the description of collective excitations and transition strength distributions of arbitrary nuclei up into the sd-shell that based on the No-C…
Ab initio many-body calculation of the 7Be(p,gamma)8B radiative capture
Petr Navratil, Robert Roth, Sofia Quaglioni
We apply the ab initio no-core shell model/resonating group method (NCSM/RGM) approach to calculate the cross section of the 7Be(p,gamma)8B radiative capture. This reaction is impo…
Continuum and Three-Nucleon Force Effects on 9Be Energy Levels
Joachim Langhammer, Petr Navratil, Sofia Quaglioni +3
We extend the recently proposed ab initio no-core shell model with continuum to include three-nucleon (3N) interactions beyond the few-body domain. The extended approach allows for…
Evolved Chiral NN+3N Hamiltonians for Ab Initio Nuclear Structure Calculations
Robert Roth, Angelo Calci, Joachim Langhammer +1
We discuss the building blocks for a consistent inclusion of chiral three-nucleon (3N) interactions into ab initio nuclear structure calculations beyond the lower p-shell. We highl…
Ab Initio Calculations of Medium-Mass Nuclei with Normal-Ordered Chiral NN+3N Interactions
Robert Roth, Sven Binder, Klaus Vobig +3
We study the use of truncated normal-ordered three-nucleon interactions in ab initio nuclear structure calculations starting from chiral two- plus three-nucleon Hamiltonians evolve…
Benchmarking ANN extrapolations of the ground-state energies and radii of Li isotopes
Marco Knöll, Matthew Lockner, Pieter Maris +4
We present a comparison of model-space extrapolation methods for No-Core Shell Model calculations of ground-state energies and root-mean-square radii in Li isotopes. In particular,…
Ab Initio Calculations of Medium-Mass Nuclei with Explicit Chiral 3N Interactions
Sven Binder, Joachim Langhammer, Angelo Calci +2
We present the first ab initio coupled-cluster calculations of medium-mass nuclei with explicit chiral three-nucleon (3N) interactions. Using a spherical formulation of coupled clu…
Hartree-Fock Many-Body Perturbation Theory for Nuclear Ground-States
Alexander Tichai, Joachim Langhammer, Sven Binder +1
We investigate the order-by-order convergence behavior of many-body perturbation theory (MBPT) as a simple and efficient tool to approximate the ground-state energy of closed-shell…
Nuclear Charge Radii of B
Bernhard MaaÃ, Thomas Hüther, Jan Krause +11
The first determination of the nuclear charge radius by laser spectroscopy for a five-electron system is reported. This is achieved by combining high-accuracy ab initio mass-shift…
Precise neural network predictions of energies and radii from the no-core shell model
Tobias Wolfgruber, Marco Knöll, Robert Roth
For light nuclei, ab initio many-body methods such as the no-core shell model are the tools of choice for predictive, high-precision nuclear structure calculations. The applicabili…