Article
Astronomy & Astrophysics
A. Jakovac, P. Mati, P. Posfay
Summary: This article proposes an approach to describe spontaneous symmetry breaking without relying on the order parameter dependent free energy. Instead, a Ward ratio is used to represent the symmetry breaking, and a unified scale evolution of the effective potential is applicable in both phases.
Article
Astronomy & Astrophysics
Christopher Jung, Jan-Hendrik Otto, Ralf-Arno Tripolt, Lorenz von Smekal
Summary: This paper explores practicable ways for self-consistent calculations of spectral functions using analytically continued functional renormalization group (aFRG) flow equations. A particularly straightforward approach proposed is to include parametrizations of self-energies based on explicit analytic one-loop expressions. The results show the importance of self-consistency at all momenta in fixing the relation between particle masses and decay thresholds, offering a sound and practicable basis for calculations in more realistic effective theories.
Article
Physics, Multidisciplinary
Pedro Liendo, Junchen Rong, Haoyu Zhang
Summary: We study conformal field theories with finite group symmetries and spontaneous symmetry breaking (SSB) phases that persist at all temperatures. By coupling two λϕ4 theories through their mass terms, we investigate the cases where the cubic symmetry group or the tetrahedral symmetry group is preserved. Our one-loop calculation in the 4-ε expansion reveals the existence of infinitely many fixed points capable of hosting SSB phases at all temperatures. Analysis of the renormalization group (RG) stability matrix shows that these fixed points have at least three relevant operators, indicating that they are tetracritical points.
Article
Astronomy & Astrophysics
R. L. P. G. Amaral, V. E. R. Lemes, O. S. Ventura, L. C. Q. Vilar
Summary: After the phase transition of a grand unified theory, the couplings of the basic interactions split from the single coupling. In the symmetric phase, the couplings associated with SU(2) and U(1) symmetries were already distinct before the electroweak breaking, as determined by the measurement of the Weinberg mixing angle. Each independent coupling should be associated with independent cocycles defined on a cohomological basis from the perspective of BRST symmetry.
Article
Physics, Multidisciplinary
Yuan Li, Shi-Cheng Xia, Constantia Alexandrou, Krzysztof Cichy, Martha Constantinou, Xu Feng, Kyriakos Hadjiyiannakou, Karl Jansen, Chuan Liu, Aurora Scapellato, Fernanda Steffens, Jacopo Tarello
Summary: In this work, we study the intrinsic, rapidity-independent soft function within the framework of large momentum effective theory using lattice QCD. After renormalization and removal of higher-twist contamination, we obtain an intrinsic soft function that is comparable to the one-loop perturbative result at large external momentum. Determining the nonperturbative soft function from first principles is crucial for our understanding of processes with small transverse momentum.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Bo Huang, Jian-You Guo, Quan Liu, Shou-Wan Chen
Summary: Pseudospin symmetry (PSS) is an important concept in the study of atomic nuclei. Using the relativistic point-coupling model, this research explores the origin and breaking mechanism of PSS in real nuclei with 208Pb as an example. The presence of PSS in the single particle spectra of heavy nuclei is confirmed, and the influence of different point-coupling interactions on PSS is investigated. It is found that the four-fermion scalar and vector couplings play a dominant role in PSS.
Article
Physics, Particles & Fields
Alessandro Giuliani, Vieri Mastropietro, Slava Rychkov
Summary: The Renormalization Group (RG) theory plays a crucial role in understanding critical phenomena, but the determination of its fixed points often relies on approximations and truncations, leading to limited accuracy in predicting physical quantities. This study provides a fully rigorous and non-perturbative characterization of RG fixed points in a model with a nonlocal kinetic term, offering a benchmark to test the validity of truncations and approximations in RG studies. Additionally, the analytic nature of the fixed point in epsilon, based on the fermionic nature of the problem, is a somewhat surprising discovery.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Constantia Alexandrou, Martha Constantinou, Kyriakos Hadjiyiannakou, Karl Jansen, Floriano Manigrasso
Summary: In this study, results on the quark unpolarized, helicity, and transversity parton distributions functions of the nucleon were presented using the quasiparton distribution approach within the lattice QCD framework. Nonzero results for the disconnected isoscalar and strange quark distributions were found, providing valuable input to the understanding of the nucleon structure.
Article
Physics, Multidisciplinary
Deshui Yu, Frank Vollmer
Summary: This study introduces a new model that takes into account the internal dynamics of active particles, and numerically investigates the PT symmetry of macroscopic- and microscopic-sized laser systems operating in the strong-coupling regime. Distinct phase diagrams are drawn based on the features of intracavity photon numbers and emission spectra. This work extends PT-symmetric optics from weak to strong coupling limits, potentially leading to nonclassical PT-symmetric light sources for integrated photonic networks and ultrasensitive sensors.
COMMUNICATIONS PHYSICS
(2021)
Article
Physics, Multidisciplinary
G. Endrodi, T. G. Kovacs, G. Marko
Summary: This study investigates spontaneously broken quantum field theories with a continuous global symmetry group using the constraint effective potential approach. It finds that the path integral is dominated by inhomogeneous field configurations related to the flatness of the effective potential in the broken phase. The study introduces the concept of differential surface tension to characterize inhomogeneities and explores possible implications for the chiral limit of QCD.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Kenji Fukushima, Takuya Shimazaki, Yuya Tanizaki
Summary: In this paper, we investigate the theta-vacuum structure and the 't Hooft anomaly at theta = pi in a simple quantum mechanical system on S-1 to examine the applicability of the functional renormalization group (fRG) approach. We find that the fRG method can accurately reproduce the ground state energy behavior for small theta, but fails near energy level crossing. We also discuss an alternative formulation using the Villain lattice action to capture the level crossing behavior of the ground states.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Romain Daviet, Nicolas Dupuis
Summary: This paper discusses the application of the nonperturbative functional renormalization group method based on Bosonization in one-dimensional quantum fluids. A Luttinger liquid in a periodic potential is used as an example. The results show that in the renormalization process, the phase field theta needs to be dynamically redefined in order to maintain its conjugate relationship with the density field phi. By deriving explicit flow equations, it is demonstrated that this approach is consistent with the results of the sine-Gordon model. The standard phenomenology of the Luttinger liquid can only be obtained through the scale-dependent parametrization of the phase field theta.
Article
Materials Science, Multidisciplinary
Michael Winer, Brian Swingle
Summary: The spectral statistics of quantum chaotic systems are influenced by global symmetries and symmetry breaking, showing clear signatures in the energy eigenvalues.
Article
Chemistry, Multidisciplinary
Mojca Vilfan, Borut Lampret, Ziga Gregorin, Luka Cmok, Andrej Vilfan, Juergen Klepp, Joachim Kohlbrecher, Patricija Hribar Bostjancic, Darja Lisjak, Alenka Mertelj
Summary: The authors report on the experimental observation of spontaneous stripe formation in a ferromagnetic ferrofluid in the presence of an oscillating external magnetic field. The striped structure is identified as elongated magnetic domains, which exhibit reorientation upon reversal of the magnetic field. The stripes are oriented perpendicular to the magnetic field and are separated by alternating flow lanes.
Article
Materials Science, Multidisciplinary
Hetian Chen, Di Yi, Ben Xu, Jing Ma, Cewen Nan
Summary: By using first-principles simulations, the properties of an edge dislocation core in SrTiO3 were explored, revealing spontaneous symmetry breaking and proposing a model to quantitatively estimate the atomic configuration of SrTiO3 under complex strain conditions.
MATERIALS TODAY PHYSICS
(2021)
Article
Physics, Particles & Fields
Holger Gies, Jobst Ziebell
EUROPEAN PHYSICAL JOURNAL C
(2020)
Review
Physics, Multidisciplinary
Alfio Bonanno, Astrid Eichhorn, Holger Gies, Jan M. Pawlowski, Roberto Percacci, Martin Reuter, Frank Saueressig, Gian Paolo Vacca
FRONTIERS IN PHYSICS
(2020)
Article
Physics, Multidisciplinary
Lukas Rammelmueller, Joaquin E. Drut, Jens Braun
Review
Physics, Multidisciplinary
C. E. Berger, L. Rammelmueller, A. C. Loheac, F. Ehmann, J. Braun, J. E. Drut
Summary: This paper reviews the theory and applications of complex stochastic quantization in the quantum many-body problem, covering various methods to address the sign problem. It discusses the mathematical foundations, provides pedagogical examples, and summarizes the challenges and practical solutions in the complex case. Additionally, recent applications of complex Langevin to quantum field theory are reviewed, with a focus on the nonrelativistic case.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2021)
Article
Physics, Multidisciplinary
Felix Karbstein, Chantal Sundqvist, Kai S. Schulze, Ingo Uschmann, Holger Gies, Gerhard G. Paulus
Summary: The study shows that the potential for discovery using solely XFEL setups can be comparable to those involving optical high-intensity lasers. Key details of x-ray optical ingredients that strongly influence the magnitude of desired signatures have been identified for currently achievable scenarios.
NEW JOURNAL OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
Holger Gies, Dimitrios Gkiatas, Luca Zambelli
Summary: In this paper, we combine a construction of BRST-invariant, nonlinear massive gauge fixing with the background field formalism. The resulting functional preserves the background-field invariance and BRST invariance of the quantum field. We verify the theory by computing the one-loop effective action and the beta function of the gauge coupling. We also study off-shell one-loop contributions and the application of the decoupling solution.
Article
Astronomy & Astrophysics
Jens Braun, Benedikt Schallmo
Summary: This study estimates the phase structure at zero temperature of dense isospin-asymmetric matter with two quark flavors using constraints from the microscopic theory of the strong interaction. It finds indications of a first-order phase transition from a color-superconducting phase to an ungapped quark-matter phase as the density increases, with this transition absent in isospin-symmetric matter. The study also provides an estimate for the speed of sound in neutron-star matter, which exceeds the asymptotic value associated with noninteracting quark gas and increases toward lower densities.
Article
Astronomy & Astrophysics
Adrian Koenigstein, Martin J. Steil, Nicolas Wink, Eduardo Grossi, Jens Braun
Summary: By reformulating the renormalization group flow equations as nonlinear heat equations, this study demonstrates the implications of dissipative character and irreversibility in RG flows. The existence of a C-/A-function is proposed to be linked to the dissipative character of RG flows and entropy production. The asymmetry in RG time and the interpretation of infrared actions as equilibrium solutions are discussed. Numerical entropy production is directly linked to irreversibility and the analysis of partial differential equations (PDEs).
Article
Astronomy & Astrophysics
Adrian Koenigstein, Martin J. Steil, Nicolas Wink, Eduardo Grossi, Jens Braun, Michael Buballa, Dirk H. Rischke
Summary: The functional renormalization group (FRG) approach is a powerful tool used in various fields to study different systems. This study introduces a novel method to solve flow equations using the analogy between RG equations and fluid dynamics. By applying this analogy to zero-dimensional quantum-field theoretical models, insights into RG flows and their interpretation, as well as the irreversibility of RG flows, can be gained. Additionally, numerical techniques developed in fluid dynamics can be applied to solve RG equations, allowing for the treatment of nonanalytic behavior in the RG flow.
Article
Optics
Felipe Attanasio, Lukas Rammelmueller, Joaquin E. Drut, Jens Braun
Summary: We nonperturbatively study the pairing behavior in high-temperature polarized two-component Fermi gases and analyze the pair-momentum distribution and shot-noise correlations. The results suggest that the dominant pairing patterns above the superfluid transition also govern the formation of condensates in the low-temperature regime.
Article
Astronomy & Astrophysics
Jens Braun, Benedikt Schallmo
Summary: We study the emergence of color superconductivity in high density strong-interaction theory, analyzing the behavior and scaling properties of diquark states and couplings. Our results suggest the existence of a maximum speed of sound at supranuclear densities.
Article
Astronomy & Astrophysics
Jens Braun, Timon Doernfeld, Benedikt Schallmo, Sebastian Toepfel
Summary: The study of dense relativistic matter is complicated and important in understanding its phase structure and thermodynamics. The introduction of regulator functions and discussion of regularization schemes are key components in the research process.
Article
Astronomy & Astrophysics
Holger Gies, Abdol Sabor Salek
Summary: This study investigates the phenomenon of gravitational catalysis at finite temperature, deriving a thermal bound on spacetime curvature to identify unaffected parameter regions. The results suggest a strong dependence of the phenomenon on curvature details and its application in quantum gravity scenarios, providing a temperature-dependent upper bound on the number of fermion flavors. The temperature dependence derived in this work helps track the fate of gravitational catalysis during the thermal history of the (quantum) Universe.
Article
Optics
Lukas Rammelmueller, Yaqi Hou, Joaquin E. Drut, Jens Braun
Summary: We theoretically study the pairing behavior of the unitary Fermi gas in the normal phase, with analysis based on spin susceptibility response to an external magnetic field. Our findings are discussed in context of the phase diagram of the spin-polarized unitary Fermi gas.
Article
Astronomy & Astrophysics
Holger Gies, Felix Karbstein, Leonhard Klar
Summary: The research focuses on tracing vacuum-fluctuation-mediated interaction processes to identify the most promising signal photon channels. By studying sum and difference frequency generation in the collision of optical laser pulses, the signal photon yield in laser pulse collisions can be enhanced.
