122 research outputs found
The Political Opposition to Alexios I Komnenos (1081–1118)
No full textThe goal of my thesis is to survey the political environment and the power struggles during the reign of Alexios I Komnenos (1081-1118). For a while, the interpretation put forward by George Orstrogorsky strongly influenced how scholarship perceived the reign of Alexios I. This author states that the political scenario in Byzantium in the 11th century was marked by the struggle between the bureaucracy and the military landed aristocracy. The seizure of power by Alexios I was, therefore, the final victory of the latter. Another important view is that, once in power, Alexios I established a family rule in which his relatives by blood and by marriage had a powerful role, for they held the highest offices both in the military and administration and had an informal influence on the emperor. This gave Alexios political strength to remain in power and crush the civil aristocracy that opposed him. Both interpretations have been partially questioned. Although the approaches that perceive a binary division between bureaucrats and the military have been clearly disproven, their echo can yet be heard in recent work. Some recent scholarship on power or intellectual struggles during his reign still resorts to arguments that have a smack of the binary interpretation. Other scholars such as Jean-Claude Cheynet dismiss this binary division, but still see relatively fixed groups within the Byzantine ruling elite. The role of Alexios’ family as a source of political support has also been questioned by scholars, mainly Peter Frankopan, who made extensive research about the power struggles during his reign. Although this recent scholarship has put forward relevant arguments, it was not sufficient to provide a convincing overview of this key-period for Byzantine History. A close look on the political alliances that formed the groups supporting an emperor or making opposition to him demonstrates that the opposition to Alexios I was not formed by clearly delineated blocks with clear goals. It was rather characterized by a wide range of interests depending on the existing political situation. His supposed lack of interest in reconquering Anatolia, which, according to current scholarship, is the greatest source of the opposition to Alexios, can be nuanced as being an important motivation only to a particular oppositional movement observed in one single episode. A similar subtle approach is also important to understand the relations between the emperor and his family. Although the contemporary or near-contemporary reports seem to confirm the important role played by the imperial family, his relatives did not support the emperor automatically, which demands a more nuanced analysis of the sources. They present the emperor in constant negotiation with his relatives, sometimes granting and sometimes curtailing power, at times being autocratic, at other times almost submissive. Besides the ad-hoc strategies adopted by the emperor to create a group of supporters marked by open contradictions, Alexios I adopted and adapted different discourses to project himself publically in order to strengthen the support to his regime and discourage opposition, which dismisses completely the traditional image of Alexios as a crude and brutal soldier-emperor. In spite of his political and discursive strategies to energize his supporters, co-opt adversaries and repress opposition were at times unsuccessful, they were often successful, which allowed a long reign and the establishment of a dynasty: clear signs of political triumph in Byzantium.266 Seite
Composition of many spins, random walks and statistics
No full textAbstractThe multiplicities of the decomposition of the product of an arbitrary number n of spin s states into irreducible SU(2) representations are computed. Two complementary methods are presented, one based on random walks in representation space and another based on the partition function of the system in the presence of a magnetic field. The large-n scaling limit of these multiplicities is derived, including nonperturbative corrections, and related to semiclassical features of the system. A physical application of these results to ferromagnetism is explicitly worked out. Generalizations involving several types of spins, as well as spin distributions, are also presented. The corresponding problem for (anti-)symmetric composition of spins is also considered and shown to obey remarkable duality and bosonization relations and exhibit novel large-n scaling properties
Quantum mechanical rules for observed observers and the consistency of quantum theory
No full textI argue that the rules of unitary quantum mechanics imply that observers who
will themselves be subject to measurements in a linear combination of
macroscopic states (``cat" measurements) cannot make reliable predictions on
the results of experiments performed after such measurements. This lifts the
inconsistency in the interpretation of quantum mechanics recently identified by
Frauchiger and Renner. The Born rules for calculating the probability of
outcomes and for communicating with other observers do not generally apply for
cat-measured observers, nor can they generally be amended to incorporate
upcoming cat measurements. Quantum mechanical rules completed with these
conditions become fully consistent.Comment: Substantially expanded version published in Nature Communications; 15
pages, no figure
Exclusion statistics and lattice random walks
No full textWe establish a connection between exclusion statistics with arbitrary integer exclusion parameter and a class of random walks on planar lattices. This connection maps the generating function for the number of closed walks of given length enclosing a given algebraic area on the lattice to the grand partition function of particles obeying exclusion statistics in a particular single-particle spectrum, determined by the properties of the random walk. Square lattice random walks, described in terms of the Hofstadter Hamiltonian, correspond to . In the case we explicitly construct a corresponding chiral random walk model on a triangular lattice, and we point to potential random walk models for higher . In this context, we also derive the form of the microscopic cluster coefficients for arbitrary exclusion statistics
Algebraic area enumeration for open lattice walks
No full textWe calculate the number of open walks of fixed length and algebraic area on a
square planar lattice by an extension of the operator method used for the
enumeration of closed walks. The open walk area is defined by closing the walks
with a straight line across their endpoints and can assume half-integer values
in lattice cell units. We also derive the length and area counting of walks
with endpoints on specific straight lines and outline an approach for dealing
with walks with fully fixed endpoints.Comment: 15 pages, 2 figure
Lattice Integrable Systems of the Haldane-Shastry Type
No full textWe present a new lattice integrable system in one dimension of the Haldane-Shastry type. It consists of spins positioned at the static equilibrium positions of particles in a corresponding classical Calogero system and interacting through an exchange term with strength inversely proportional to the square of their distance. We achieve this by viewing the Haldane-Shastry system as a high-interaction limit of the Sutherland system of particles with internal degrees of freedom and identifying the same limit in a corresponding Calogero system. The commuting integrals of motion of this system are found using the exchange operator formalism.We present a new lattice integrable system in one dimension of the Haldane-Shastry type. It consists of spins positioned at the static equilibrium positions of particles in a corresponding classical Calogero system and interacting through an exchange term with strength inversely proportional to the square of their distance. We achieve this by viewing the Haldane-Shastry system as a high-interaction limit of the Sutherland system of particles with internal degrees of freedom and identifying the same limit in a corresponding Calogero system. The commuting integrals of motion of this system are found using the exchange operator formalism
Ferromagnets from higher SU(N) representations
No full textWe present a general formalism for deriving the thermodynamics of ferromagnets consisting of “atoms” carrying an arbitrary irreducible representation of SU(N) and coupled through long-range two-body quadratic interactions. Using this formalism, we derive the thermodynamics and phase structure of ferromagnets with atoms in the doubly symmetric or doubly antisymmetric irreducible representations. The symmetric representation leads to a paramagnetic and a ferromagnetic phase with transitions similar to the ones for the fundamental representation studied before. The antisymmetric representation presents qualitatively new features, leading to a paramagnetic and two distinct ferromagnetic phases that can coexist over a range of temperatures, two of them becoming metastable. Our results are relevant to magnetic systems of atoms with reduced symmetry in their interactions compared to the fundamental case. © 2025 The Author(s
Encomium to the Monastic Life: An Unedited Poem of Alexios Makrembolites
No full textThis article presents the first critical edition of a metrical Encomium to the monastic life written by the fourteenth-century Byzantine author Alexios Makrembolites. The text is preserved in only one manuscript (Hierosolymitanus Sabbaiticus gr. 417). Makrembolites, after referring to the constant rejuvenation of the nature, wonders why people are drawn towards material goods and not to spiritual ones, distancing themselves from the immortality offered by a life close to God. After apologizing for his sinful life, he praises monastic life which he believes he should follow in order to bring an end to all his pains.
Inclusion statistics and particle condensation in 2 dimensions
No full textWe propose a new type of quantum statistics, which we call inclusion
statistics, in which particles tend to coalesce more than ordinary bosons.
Inclusion statistics is defined in analogy with exclusion statistics, in which
statistical exclusion is stronger than in Fermi statistics, but now
extrapolating beyond Bose statistics, resulting in statistical inclusion. A
consequence of inclusion statistics is that the lowest space dimension in which
particles can condense in the absence of potentials is , unlike for
the usual Bose-Einstein condensation. This reduction in the dimension happens
for any inclusion stronger than bosons, and the critical temperature increases
with stronger inclusion. Possible physical realizations of inclusion statistics
involving attractive interactions between bosons may be experimentally
achievable.Comment: 12 pages, 0 figur
Mapping the Calogero model on the Anyon model
No full textInternational audienceWe explicitly map the N -body one dimensional Calogero eigenstates in a harmonic well to the lowest Landau level sector of N -body eigenstates of the two dimensional anyon model in a harmonic well. The mapping is achieved in terms of a convolution kernel that uses as input the scattering eigenstates of the free Calogero model on the infinite line, which are obtained in an operator formulation
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