118 research outputs found
Black-holes, topological strings and large N phase transitions
The counting of microstates of BPS black-holes on local Calabi-Yau of the
form is explored
by computing the partition function of q-deformed Yang-Mills theory on .
We obtain, at finite , the instanton expansion of the gauge theory. It can
be written exactly as the partition function for U(N) Chern-Simons gauge theory
on a Lens space, summed over all non-trivial vacua, plus a tower of
non-perturbative instanton contributions. In the large limit we find a
peculiar phase structure in the model. At weak string coupling the theory
reduces to the trivial sector and the topological string partition function on
the resolved conifold is reproduced in this regime. At a certain critical
point, instantons are enhanced and the theory undergoes a phase transition into
a strong coupling regime. The transition from the strong coupling phase to the
weak coupling phase is of third order.Comment: 16 pages, 3 figures; Invited talk given at QG05, Cala Gonone (Italy),
September 200
Concurrent Chorioptic Mange and Dermatophytosis in Dairy Goats: A Case Report
SIMPLE SUMMARY: Chorioptes mites are particularly common in goats, with infestations usually subclinical and often asymptomatic. In the present case, many animals had a severe clinical presentation, possibly due to the associated dermatophyte infection (Trichophyton verrucosum), since a concurrent or underlying disease may exacerbate clinical response. Goats were treated topically with pour-on Eprinomectin (1 mg/kg), while an enilconazole solution was used for environmental disinfection against dermatophyte spores. ABSTRACT: A concurrent chorioptic mange and dermatophytosis outbreak occurred in a goat flock in northwestern Italy. Sanitation of the flock was obtained following pour-on eprinomectin application at a dose of 1 mg/kg; enilconazole was used for environmental disinfection against dermatophyte spores
Urban informality and confinement: toward a relational framework
In the 21st century, a growing number of people live ‘informal’ lives within fissures between legality and informality. Concomitantly, power relations are increasingly expressed through devices of confinement. While urban informality and confinement are on the rise often occurring simultaneously, scholars have so far studied them separately. By contrast, this article proposes a new framework for analysing urban informality and confinement relationally. It generates new insights into the role of informality in the (re)production of confinement and, vice versa, the role of confinement in shaping informal practices. While these insights are valuable for urban studies in general, the article charts new lines of research on urban marginality. It also discusses how the six articles included in this special issue signal the heuristic potential of this relational framework by empirically examining distinct urban configurations of ‘confined informalities’ and ‘informal confinements’ across the Global North and the Global South
Gauge-Invariant Resummation Formalism and Unitarity in Non-Commutative QED
We re-examine the perturbative properties of four-dimensional non-commutative
QED by extending the pinch techniques to the theta-deformed case. The explicit
independence of the pinched gluon self-energy from gauge-fixing parameters, and
the absence of unphysical thresholds in the resummed propagators permits a
complete check of the optical theorem for the off-shell two-point function. The
known anomalous (tachyonic) dispersion relations are recovered within this
framework, as well as their improved version in the (softly broken) SUSY case.
These applications should be considered as a first step in constructing
gauge-invariant truncations of the Schwinger-Dyson equations in the
non-commutative case. An interesting result of our formalism appears when
considering the theory in two dimensions: we observe a finite gauge-invariant
contribution to the photon mass because of a novel incarnation of IR/UV mixing,
which survives the commutative limit when matter is present.Comment: 30 pages, 2 eps figure, uses axodraw. Citations adde
Insight into summer drought in southern Italy: palaeohydrological evolution of Lake Pergusa (Sicily) in the last 6700 years
The Sicily region (central Mediterranean) is at high risk of drying and desertification caused by current warming and land management. The aim of this study is to place current climatic changes within the past trajectories and natural climatic variability of the Holocene. For this we re-examine a sediment core retrieved at Lake Pergusa covering the last ca. 6700 years. A multiproxy investigation, and in particular the oxygen isotope composition of lacustrine carbonate (delta O-18(c)), allowed us to reconstruct decadal- to centennial-scale hydrological changes. The wettest period occurred between ca. 6700 and 6000 cal a bp. The delta O-18(c) record indicates a new period of wetter conditions between ca. 3700 and 2400 cal a bp. In particular, a delta O-18(c) minimum between 2850 and 2450 cal a bp overlaps with the period of the 'Great Solar Minimum' and corresponds to a dramatic reduction of arboreal pollen (AP%) and to an increase in synanthropic pollen, marking the onset of Greek colonization in the region. The longest driest interval corresponds to the Medieval Climate Anomaly, whereas the highest delta O-18(c) values are recorded in the last 150 years. The trend of the last 3000 years suggests that, considering future climate projections, the area will experience unprecedented drying exacerbated by human impact
Analytic Continuation of Liouville Theory
Correlation functions in Liouville theory are meromorphic functions of the
Liouville momenta, as is shown explicitly by the DOZZ formula for the
three-point function on the sphere. In a certain physical region, where a real
classical solution exists, the semiclassical limit of the DOZZ formula is known
to agree with what one would expect from the action of the classical solution.
In this paper, we ask what happens outside of this physical region. Perhaps
surprisingly we find that, while in some range of the Liouville momenta the
semiclassical limit is associated to complex saddle points, in general
Liouville's equations do not have enough complex-valued solutions to account
for the semiclassical behavior. For a full picture, we either must include
"solutions" of Liouville's equations in which the Liouville field is
multivalued (as well as being complex-valued), or else we can reformulate
Liouville theory as a Chern-Simons theory in three dimensions, in which the
requisite solutions exist in a more conventional sense. We also study the case
of "timelike" Liouville theory, where we show that a proposal of Al. B.
Zamolodchikov for the exact three-point function on the sphere can be computed
by the original Liouville path integral evaluated on a new integration cycle.Comment: 86 pages plus appendices, 9 figures, minor typos fixed, references
added, more discussion of the literature adde
Affine sl(N) conformal blocks from N=2 SU(N) gauge theories
Recently Alday and Tachikawa proposed a relation between conformal blocks in
a two-dimensional theory with affine sl(2) symmetry and instanton partition
functions in four-dimensional conformal N=2 SU(2) quiver gauge theories in the
presence of a certain surface operator. In this paper we extend this proposal
to a relation between conformal blocks in theories with affine sl(N) symmetry
and instanton partition functions in conformal N=2 SU(N) quiver gauge theories
in the presence of a surface operator. We also discuss the extension to
non-conformal N=2 SU(N) theories.Comment: 40 pages. v2: minor changes and clarification
On "Dotsenko-Fateev" representation of the toric conformal blocks
We demonstrate that the recent ansatz of arXiv:1009.5553, inspired by the
original remark due to R.Dijkgraaf and C.Vafa, reproduces the toric conformal
blocks in the same sense that the spherical blocks are given by the integral
representation of arXiv:1001.0563 with a peculiar choice of open integration
contours for screening insertions. In other words, we provide some evidence
that the toric conformal blocks are reproduced by appropriate beta-ensembles
not only in the large-N limit, but also at finite N. The check is explicitly
performed at the first two levels for the 1-point toric functions.
Generalizations to higher genera are briefly discussed.Comment: 10 page
A quantum isomonodromy equation and its application to N=2 SU(N) gauge theories
We give an explicit differential equation which is expected to determine the
instanton partition function in the presence of the full surface operator in
N=2 SU(N) gauge theory. The differential equation arises as a quantization of a
certain Hamiltonian system of isomonodromy type discovered by Fuji, Suzuki and
Tsuda.Comment: 15 pages, v2: typos corrected and references added, v3: discussion,
appendix and references adde
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