| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 9 / 9
Na začetekNa prejšnjo stran1Na naslednjo stranNa konec
1.
Quadrillion F-theory compactifications with the exact chiral spectrum of the standard model
Mirjam Cvetič, James Halverson, Ling Lin, Mingqiang Liu, Jianjun Paul Tian, 2019, izvirni znanstveni članek

Opis: We present O(10(15)) string compactifications with the exact chiral spectrum of the standard model of particle physics. This ensemble of globally consistent F-theory compactifications automatically realizes gauge coupling unification. Utilizing the power of algebraic geometry, all global consistency conditions can be reduced to a single criterion on the base of the underlying elliptically fibered Calabi-Yau fourfolds. For toric bases, this criterion only depends on an associated polytope and is satisfied for at least O(10(15)) bases, each of which defines a distinct compactification.
Ključne besede: FLUX, F-theory, string compactifications, chiral spectrum
Objavljeno v DKUM: 23.10.2023; Ogledov: 300; Prenosov: 7
.pdf Celotno besedilo (184,32 KB)
Gradivo ima več datotek! Več...

2.
Yukawa hierarchies in global F-theory models
Mirjam Cvetič, Ling Lin, Mingqiang Liu, Hao Y. Zhang, Gianluca Zoccarato, 2020, izvirni znanstveni članek

Opis: We argue that global F-theory compactifications to four dimensions gener- ally exhibit higher rank Yukawa matrices from multiple geometric contributions known as Yukawa points. The holomorphic couplings furthermore have large hierarchies for generic complex structure moduli. Unlike local considerations, the compact setup realizes these features all through geometry, and requires no instanton corrections. As an example, we consider a concrete toy model with SU(5) x U(1) gauge symmetry. From the geometry, we find two Yukawa points for the 10-25-4 coupling, producing a rank two Yukawa matrix. Our methods allow us to track all complex structure dependencies of the holomorphic couplings and study the ratio numerically. This reveals hierarchies of O(10(5)) and larger on a full-dimensional subspace of the moduli space.
Ključne besede: F-theory, supersymmetric effective theories
Objavljeno v DKUM: 16.10.2023; Ogledov: 117; Prenosov: 7
.pdf Celotno besedilo (930,60 KB)
Gradivo ima več datotek! Več...

3.
Root bundles and towards exact matter spectra of F-theory MSSMs
Martin Bies, Mirjam Cvetič, Ron Donagi, Mingqiang Liu, Marielle Ong, 2021, izvirni znanstveni članek

Opis: Motivated by the appearance of fractional powers of line bundles in studies of vector-like spectra in 4d F-theory compactifications, we analyze the structure and origin of these bundles. Fractional powers of line bundles are also known as root bundles and can be thought of as generalizations of spin bundles. We explain how these root bundles are linked to inequivalent F-theory gauge potentials of a G(4)-flux. While this observation is interesting in its own right, it is particularly valuable for F-theory Standard Model constructions. In aiming for MSSMs, it is desired to argue for the absence of vector-like exotics. We work out the root bundle constraints on all matter curves in the largest class of currently-known F-theory Standard Model constructions without chiral exotics and gauge coupling unification. On each matter curve, we conduct a systematic "bottom"-analysis of all solutions to the root bundle constraints and all spin bundles. Thereby, we derive a lower bound for the number of combinations of root bundles and spin bundles whose cohomologies satisfy the physical demand of absence of vector-like pairs. On a technical level, this systematic study is achieved by a well-known diagrammatic description of root bundles on nodal curves. We extend this description by a counting procedure, which determines the cohomologies of so-called limit root bundles on full blow-ups of nodal curves. By use of deformation theory, these results constrain the vector-like spectra on the smooth matter curves in the actual F-theory geometry.
Ključne besede: F-theory, differential geometry, algebraic geometry
Objavljeno v DKUM: 16.10.2023; Ogledov: 177; Prenosov: 11
.pdf Celotno besedilo (979,06 KB)
Gradivo ima več datotek! Več...

4.
Statistics of limit root bundles relevant for exact matter spectra of F-theory MSSMs
Martin Bies, Mirjam Cvetič, Mingqiang Liu, 2021, izvirni znanstveni članek

Opis: In the largest, currently known, class of one quadrillion globally consistent F-theory Standard Models with gauge coupling unification and no chiral exotics, the vectorlike spectra are counted by cohomologies of root bundles. In this work, we apply a previously proposed method to identify toric base threefolds, which are promising to establish F-theory Standard Models with exactly three quark doublets and no vectorlike exotics in this representation. The base spaces in question are obtained from triangulations of 708 polytopes. By studying root bundles on the quark-doublet curve Cð3;2Þ1=6 and employing well-known results about desingularizations of toric K3 surfaces, we derive a triangulation independent lower bound Nˇ ð3Þ P for the number Nð3Þ P of root bundles on Cð3;2Þ1=6 with exactly three sections. The ratio Nˇ ð3Þ P =NP, where NP is the total number of roots on Cð3;2Þ1=6 , is largest for base spaces associated with triangulations of the eighth three-dimensional polytope Δ∘ 8 in the Kreuzer-Skarke list. For each of these Oð1015Þ threefolds, we expect that many root bundles on Cð3;2Þ1=6 are induced from F-theory gauge potentials and that at least every 3000th root on Cð3;2Þ1=6 has exactly three global sections and thus no exotic vectorlike quark-doublet modes.
Ključne besede: astrophysics, compactification, string theory models, geometry, higher-dimensional field theories, mathematical physics, quantum fields in curved spacetime, string phenomenology, supersymmetric models, topology
Objavljeno v DKUM: 16.10.2023; Ogledov: 123; Prenosov: 7
.pdf Celotno besedilo (444,13 KB)
Gradivo ima več datotek! Več...

5.
Multifractality in quasienergy space of coherent states as a signature of quantum chaos
Qian Wang, Marko Robnik, 2021, izvirni znanstveni članek

Opis: We present the multifractal analysis of coherent states in kicked top model by expanding them in the basis of Floquet operator eigenstates. We demonstrate the manifestation of phase space structures in the multifractal properties of coherent states. In the classical limit, the classical dynamical map can be constructed, allowing us to explore the corresponding phase space portraits and to calculate the Lyapunov exponent. By tuning the kicking strength, the system undergoes a transition from regularity to chaos. We show that the variation of multifractal dimensions of coherent states with kicking strength is able to capture the structural changes of the phase space. The onset of chaos is clearly identified by the phase-space-averaged multifractal dimensions, which are well described by random matrix theory in a strongly chaotic regime. We further investigate the probability distribution of expansion coefficients, and show that the deviation between the numerical results and the prediction of random matrix theory behaves as a reliable detector of quantum chaos.
Ključne besede: quantum chaos, multifractal analysis, kicked top, coherent states
Objavljeno v DKUM: 13.10.2023; Ogledov: 251; Prenosov: 12
.pdf Celotno besedilo (3,13 MB)
Gradivo ima več datotek! Več...

6.
Machine learning and algebraic approaches towards complete matter spectra in 4d F-theory
Martin Bies, Mirjam Cvetič, Ron Donagi, Ling Lin, Mingqiang Liu, Fabian Ruehle, 2021, izvirni znanstveni članek

Opis: Motivated by engineering vector-like (Higgs) pairs in the spectrum of 4d Ftheory compactifications, we combine machine learning and algebraic geometry techniques to analyze line bundle cohomologies on families of holomorphic curves. To quantify jumps of these cohomologies, we first generate 1.8 million pairs of line bundles and curves embedded in dP3, for which we compute the cohomologies. A white-box machine learning approach trained on this data provides intuition for jumps due to curve splittings, which we use to construct additional vector-like Higgs-pairs in an F-Theory toy model. We also find that, in order to explain quantitatively the full dataset, further tools from algebraic geometry, in particular Brill-Noether theory, are required. Using these ingredients, we introduce a diagrammatic way to express cohomology jumps across the parameter space of each family of matter curves, which reflects a stratification of the F-theory complex structure moduli space in terms of the vector-like spectrum. Furthermore, these insights provide an algorithmically efficient way to estimate the possible cohomology dimensions across the entire parameter space.
Ključne besede: Differential Geometry, Algebraic Geometry, F-Theory, Flux Compactifications, Field Theories, Higher Dimensions
Objavljeno v DKUM: 13.10.2023; Ogledov: 158; Prenosov: 7
.pdf Celotno besedilo (889,92 KB)
Gradivo ima več datotek! Več...

7.
Quantum chaos in the extended Dicke model
Qian Wang, 2022, izvirni znanstveni članek

Opis: We systematically study the chaotic signatures in a quantum many-body system consisting of an ensemble of interacting two-level atoms coupled to a single-mode bosonic field, the so-called extended Dicke model. The presence of the atom–atom interaction also leads us to explore how the atomic interaction affects the chaotic characters of the model. By analyzing the energy spectral statistics and the structure of eigenstates, we reveal the quantum signatures of chaos in the model and discuss the effect of the atomic interaction. We also investigate the dependence of the boundary of chaos extracted from both eigenvalue-based and eigenstate-based indicators on the atomic interaction. We show that the impact of the atomic interaction on the spectral statistics is stronger than on the structure of eigenstates. Qualitatively, the integrablity-to-chaos transition found in the Dicke model is amplified when the interatomic interaction in the extended Dicke model is switched on.
Ključne besede: quantum chaos, extended Dicke model, spectral statistics, eigenstate structure
Objavljeno v DKUM: 13.10.2023; Ogledov: 156; Prenosov: 11
.pdf Celotno besedilo (3,46 MB)
Gradivo ima več datotek! Več...

8.
Effects of adaptive degrees of trust on coevolution of quantum strategies on scale-free networks
Qiang Li, Minyou Chen, Matjaž Perc, Azhar Iqbal, Derek Abbott, 2013, izvirni znanstveni članek

Opis: We study the impact of adaptive degrees of trust on the evolution of cooperation in the quantum prisoner's dilemma game. In addition to the strategies, links between players are also subject to evolution. Starting with a scale-free interaction network, players adjust trust towards their neighbors based on received payoffs. The latter governs the strategy adoption process, while trust governs the rewiring of links. As soon as the degree of trust towards a neighbor drops to zero, the link is rewired to another randomly chosen player within the network. We find that for small temptations to defect cooperators always dominate, while for intermediate and strong temptations a single quantum strategy is able to outperform all other strategies. In general, reciprocal trust remains within close relationships and favors the dominance of a single strategy. Due to coevolution, the power-law degree distributions transform to Poisson distributions.
Ključne besede: evolutionary games, quantum strategies, coevolution, random networks, cooperation, statistical physics of social systems
Objavljeno v DKUM: 23.06.2017; Ogledov: 864; Prenosov: 351
.pdf Celotno besedilo (669,03 KB)
Gradivo ima več datotek! Več...

9.
Coevolution of quantum and classical strategies on evolving random networks
Qiang Li, Azhar Iqbal, Matjaž Perc, Minyou Chen, Derek Abbott, 2013, izvirni znanstveni članek

Opis: We study the coevolution of quantum and classical strategies on weighted and directed random networks in the realm of the prisoners dilemma game. During the evolution, agents can break and rewire their links with the aim of maximizing payoffs, and they can also adjust the weights to indicate preferences, either positive or negative, towards their neighbors. The network structure itself is thus also subject to evolution. Importantly, the directionality of links does not affect the accumulation of payoffs nor the strategy transfers, but serves only to designate the owner of each particular link and with it the right to adjust the link as needed. We show that quantum strategies outperform classical strategies, and that the critical temptation to defect at which cooperative behavior can be maintained rises, if the network structure is updated frequently. Punishing neighbors by reducing the weights of their links also plays an important role in maintaining cooperation under adverse conditions. We find that the self-organization of the initially random network structure, driven by the evolutionary competition between quantum and classical strategies, leads to the spontaneous emergence of small average path length and a large clustering coefficient.
Ključne besede: evolutionary games, quantum strategies, coevolution, random networks, cooperation
Objavljeno v DKUM: 19.06.2017; Ogledov: 997; Prenosov: 346
.pdf Celotno besedilo (803,96 KB)
Gradivo ima več datotek! Več...

Iskanje izvedeno v 0.21 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici