Article
Astronomy & Astrophysics
Jan Ambjorn, Yuri Makeenko
Summary: The string susceptibility gamma(str) for the regularized Nambu-Goto string in various dimensions was computed, and it was found that gamma(str) = 1/2 in the range 2 < d < 26, consistent with previous results obtained for lattice strings.
MODERN PHYSICS LETTERS A
(2021)
Article
Physics, Particles & Fields
Yuri Makeenko
Summary: In this study, I investigated the higher-order terms of the Seeley expansion of the heat kernel and their impact on the string effective action, demonstrating anomalous contributions for the Polyakov string consistent with the KPZ-DDK result for the Liouville theory. However, a deviation was found for the Nambu-Goto string formulation, suggesting potential differences between the two string descriptions.
Article
Astronomy & Astrophysics
Hiroshi Kozaki, Tatsuhiko Koike, Yoshiyuki Morisawa, Hideki Ishihara
Summary: We study the classical dynamics of Nambu-Goto strings with null symmetry in curved spacetimes. In the case of null symmetry, an almost contact structure associated with the metric dual 1-form eta of the null Killing vector field emerges naturally and determines the allowed class of string worldsheets.
Article
Astronomy & Astrophysics
Jose J. Blanco-Pillado, Daniel Jimenez-Aguilar, Joanes Lizarraga, Asier Lopez-Eiguren, Ken D. Olum, Ander Urioa, Jon Urrestillaa
Summary: We compare the dynamics of cosmic string loops obtained in cosmological field theory simulations with the expected motion according to the Nambu-Goto action. It is found that these loops generally follow the trajectories predicted within the NG effective theory, except in regions of high curvature where energy is emitted from the loop in the form of massive radiation. This energy loss continues until the loops self-intersect or disappear before completing a single oscillation. The findings are important for interpreting the results from cosmological field theory simulations and their extrapolation to a cosmological context.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Review
Physics, Multidisciplinary
Soma Sanyal
Summary: Nambu Goto cosmic strings are formed from symmetry breaking phase transitions in the early universe, evolving into a complex network of long strings and loops that generate density inhomogeneities of different sizes as they move through the early universe, affecting the evolution of the universe and the generation of seed magnetic fields in the early universe.
EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS
(2022)
Article
Astronomy & Astrophysics
Dimitra Karabali, Antonina Maj, V. P. Nair
Summary: This article studies the parametrization of gauge fields on complex projective spaces of arbitrary dimension, which is a generalization of the real two-dimensional case. The parametrization allows the gauge transformations to act homogeneously on the fields, facilitating a manifestly gauge-invariant analysis. In the case of four dimensions, the nature of the effective action due to the interaction between chiral scalars and gauge fields is considered, and important terms such as a possible gauge-invariant mass term and a finite four-dimensional Wess-Zumino-Witten (WZW) action are identified.
Article
Astronomy & Astrophysics
Mohammed Khalil, Raissa F. P. Mendes, Nestor Ortiz, Jan Steinhoff
Summary: In certain scalar-field extensions to general relativity, the effect of dynamical scalarization, where scalar charges develop on compact objects in an inspiraling binary, can be modeled using effective-field-theory methods applied to the binary within the post-Newtonian approximation. Previous studies focused on the adiabatic case for quasicircular orbits. This work explores the full dynamical evolution around the phase transition to the scalarized regime, considering generic orbits and quantifying nonadiabatic behavior. The results indicate that the full dynamics must be taken into account to reliably predict the onset of scalarization.
Article
Physics, Particles & Fields
Tomas Ortin
Summary: In this study, the toroidal compactification of the Bergshoeff-de Roo version of the Heterotic Superstring effective action to first order in alpha ' was performed. The dimensionally-reduced action was then utilized to derive a manifestly-O(n, n)-invariant Wald entropy formula, which was applied to calculate the entropy of alpha ' -corrected, 4-dimensional, 4-charge, static, extremal, supersymmetric black holes.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Alireza Sharifian, Nuno Cardoso, Pedro Bicudo
Summary: We compute the spectra of flux tubes between a static quark-antiquark pair in SU(3) gauge lattice QCD and compare the results with the Nambu-Goto string model. Evidence for the coupling of a massive particle to specific flux tubes is provided. The study yields important insights into possible novel phenomena in particle physics.
Article
Physics, Particles & Fields
Yasser Akou, Mohammad R. Garousi
Summary: In this paper, the classical effective action of the O-plane and its corresponding boundary terms in type II superstring theories at order alpha ' 2 and for NS-NS couplings are investigated using constraints of gauge transformations and string duality transformations. It is found that these constraints fix the bulk action and its corresponding boundary terms up to one overall factor, while also producing three multiplets in the boundary action with coefficients independent of the bulk couplings under string dualities.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Nuclear
Yuri Makeenko
Summary: I investigate the Nambu-Goto and Polyakov strings, taking into account higher-derivative terms in the emergent action for the metric tensor. These terms are classically negligible but become relevant quantumly. Using the conformal field theory technique by KPZ-DDK, I compute the conformal dimension and central charge in the one-loop approximation, which distinguish the Nambu-Goto and Polyakov strings. I confirm the results by explicit quantum field theory computations and Pauli-Villars regularization.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2023)
Article
Astronomy & Astrophysics
Shekhar Adhikari, Ian M. Lewis, Matthew Sullivan
Summary: The assumption of simplified models is that only a few new particles and interactions are accessible at the LHC, with all other new particles being heavy and decoupled. However, even when the cutoff scale is 3 TeV, new effective interactions involving Standard Model particles can significantly impact interpretations of Higgs precision measurements and scalar searches. The power counting in BSM-EFT strongly depends on the processes and parameter space being considered.
Article
Astronomy & Astrophysics
Sarka Todorova-Nova
Summary: Researchers studied baryon production within the framework of quantized fragmentation of a QCD string, finding that baryons appear in a fairly intuitive way through causally connected string breakups. By using a simple helical approximation of a QCD flux tube with parameters constrained by a mass spectrum of light mesons, they were able to reproduce the masses of light baryons.
Article
Physics, Mathematical
S. Martinoli, M. Schiavina
Summary: This study investigates the relationship between the Batalin-Vilkovisky data and Polyakov string theory with a boundary, demonstrating their compatibility for BV-quantisation on manifolds with boundary. It also highlights the failure of the analogous formulation in Nambu-Goto string theory. Additionally, the reduced phase spaces and their relation in both models for any target d-dimensional Lorentzian manifold are succinctly described.
LETTERS IN MATHEMATICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Fabio L. Braghin
Summary: In this study, the flavor-dependent NJL-type interactions with one-gluon exchange quark-antiquark interaction were considered, leading to resolved coupling constants in all channels in the long-wavelength limit. The effect of flavor-dependent coupling constants on the masses of pions, kaons, and light scalar mesons was found to be significant compared to the effect of non-degeneracy of u, d, and s quark masses.
Article
Physics, Particles & Fields
J. Ambjorn, G. Czelusta, J. Gizbert-Studnicki, A. Gorlich, J. Jurkiewicz, D. Nemeth
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Physics, Particles & Fields
J. Ambjorn, Y. Watabiki
Article
Physics, Multidisciplinary
Jan Ambjorn, Jakub Gizbert-Studnicki, Andrzej Gorlich, Jerzy Jurkiewicz, Renate Loll
FRONTIERS IN PHYSICS
(2020)
Article
Astronomy & Astrophysics
Jan Ambjorn, Yuki Hiraga, Yoshiyasu Ito, Yuki Sato
Summary: By quantizing the two-dimensional projectable Horava-Lifshitz gravity with bi-local and spacelike wormhole interaction, we find that the resulting quantum Hamiltonian coincides with that obtained through summing over all genus in the string field theory, implying that the wormhole interaction can be interpreted as a splitting or joining interaction of one-dimensional strings.
Article
Astronomy & Astrophysics
J. Ambjorn, Y. Sato, Y. Watabiki
Summary: In a two-dimensional model of quantum gravity, the summation over all possible wormhole configurations leads to a Coleman mechanism in which the cosmological constant has no effect on large universes. Observers unable to observe changes in the topology will naturally interpret measurements of universe size as being caused by fluctuating cosmological constants rather than fluctuating spacetime topology.
Review
Astronomy & Astrophysics
Jan Ambjorn, Zbigniew Drogosz, Jakub Gizbert-Studnicki, Andrzej Gorlich, Jerzy Jurkiewicz, Daniel Nemeth
Summary: Lattice formulations of gravity, such as CDT, are used to study non-perturbative aspects of quantum gravity. The higher-order phase transitions observed in CDT can define a continuum limit of the lattice theory, and studying the model with a toroidal spatial topology can provide insights into the nature of typical quantum fluctuations of geometry. Additionally, including massless scalar fields in the path integral of CDT can have a significant impact on the geometry.
Article
Astronomy & Astrophysics
Jan Ambjorn, Zbigniew Drogosz, Jakub Gizbert-Studnicki, Andrzej Gorlich, Jerzy Jurkiewicz, Daniel Nemeth
Summary: This article discusses the complex geometries extracted from the path integral of a quantum theory of gravity, showing that using suitable coordinate systems and scalar fields that solve Laplace's equation can help understand cosmic voids and filaments structures. It also demonstrates the dramatic changes in geometry that can occur when scalar fields are dynamically coupled to the geometry.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Particles & Fields
J. Ambjorn, Z. Drogosz, J. Gizbert-Studnicki, A. Gorlich, J. Jurkiewicz, D. Nemeth
Summary: By using computer simulations, the geometry of a typical quantum universe is studied with coordinate defined by classical scalar fields. The field configurations reveal cosmic web structures similar to the present-day universe.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Jan Ambjorn, Yuri Makeenko
Summary: The string susceptibility gamma(str) for the regularized Nambu-Goto string in various dimensions was computed, and it was found that gamma(str) = 1/2 in the range 2 < d < 26, consistent with previous results obtained for lattice strings.
MODERN PHYSICS LETTERS A
(2021)
Article
Physics, Multidisciplinary
J. Ambjorn, Z. Drogosz, J. Gizbert-Studnicki, A. Gorlich, J. Jurkiewicz, D. Nemeth
Summary: By using Monte Carlo computer simulations, the study investigates the impact of matter fields on the geometry of a typical quantum universe in the causal dynamical triangulations model of lattice quantum gravity. A phase transition caused by the scalar field is observed and it can change the topology of quantum universes with nontrivial topology to a simply connected one.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
J. Ambjorn, Y. Watabiki
Summary: In this paper, a modified Friedmann equation derived from a W-3 algebra-based universe model is proposed to explain the discrepancy between the Hubble constants obtained from CMB data and supernova data.
MODERN PHYSICS LETTERS A
(2022)
Article
Physics, Particles & Fields
J. Ambjorn, J. Gizbert-Studnicki, A. Gorlich, D. Nemeth
Summary: This article completes the phase diagram of Causal Dynamical Triangulations (CDT) for the three-torus spatial topology by analyzing the A - B and B - C phase transitions. It is observed that the order of phase transitions of spacetime geometries can depend on the topology of spacetime.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
J. Ambjorn, Y. Watabiki
Summary: This paper suggests that the late time expansion of the Universe is caused by the absorption of baby universes, and describes the late time cosmology using a modified Friedmann equation. The modified equation can achieve agreement with the measured values of the Hubble parameter H(z) between 0 and the time corresponding to the last scattering of cosmic microwave background (CMB) for a suitable choice of parameter B. Additionally, this modified Friedmann equation also accurately describes other aspects of the large-scale structure of the Universe.
MODERN PHYSICS LETTERS A
(2023)
Article
Astronomy & Astrophysics
J. Ambjorn, Z. Drogosz, A. Gorlich, J. Jurkiewicz
Summary: The study reveals that the geometry of a quantum universe with a four-torus topology consists of a small semiclassical toroidal bulk part surrounded by many outgrowths with almost spherical topologies, yet still quite fractal.
Article
Astronomy & Astrophysics
Jan Ambjorn, Yuki Sato, Tomo Tanaka
