15 research outputs found
Modular anomaly equations in N =2* theories and their large-N limit
We propose a modular anomaly equation for the prepotential of the N=2* super Yang-Mills theory on R^4 with gauge group U(N) in the presence of an Omega-background. We then study the behaviour of the prepotential in a large-N limit, in which N goes to infinity with the gauge coupling constant kept fixed. In this regime instantons are not suppressed. We focus on two representative choices of gauge theory vacua, where the vacuum expectation values of the scalar fields are distributed either homogeneously or according to the Wigner semi-circle law. In both cases we derive an all-instanton exact formula for the prepotential. As an application, we show that the gauge theory partition function on S^4 at large N localises around a Wigner distribution for the vacuum expectation values leading to a very simple expression in which the instanton contribution becomes independent of the coupling constant
Multi instanton tests of holography
Gauge theories living on stacks of D7-branes are holographically related to
IIB gravitational backgrounds with a varying axion-dilaton field (F-theory).
The axion-dilaton field is generated by D7, O7 and D-instanton sources and can
be written in terms of the chiral correlators of the eight dimensional gauge
theory living on the D7-branes. Using localization techniques, we prove that
the same correlators determine the gauge coupling of the four-dimensional N=2
supersymmetric SU(2) gauge theories living on the elementary D3-brane which
probes the F-theory geometries.Comment: 18 page
Non-perturbative gauge/gravity correspondence in N=2 theories
We derive the exact supergravity profile for the twisted scalar field emitted
by a system of fractional D3 branes at a Z2 orbifold singularity supporting N=2
quiver gauge theories with unitary groups and bifundamental matter. At the
perturbative level this twisted field is "dual" to the gauge coupling but it is
corrected non-perturbatively by an infinite tower of fractional D-instantons.
The explicit microscopic description allows to derive the gravity profile from
disk amplitudes computing the emission rate of the twisted scalar field in
terms of chiral correlators in the dual gauge theory. We compute these quantum
correlators using multi-instanton localization techniques and/or Seiberg-Witten
analysis. Finally, we discuss a non-perturbative relation between the twisted
scalar and the effective coupling of the gauge theory for some simple choices
of the brane set ups.Comment: 42 pages. 3 figures, PDFLaTe
Branes, U-folds and hyperelliptic fibrations
We construct a class of supersymmetric vacua of type IIB string theory
describing systems of three- and seven-branes non-perturbatively completed by
brane instantons. The vacua are specified by a set of holomorphic functions
defined over a complex plane up to non-trivial U-duality monodromies around the
brane locations. In the simplest setting, the solutions can be seen as a
generalization of F-theory elliptic fibrations, where the torus fiber is
replaced by a genus two Riemann surface with periods encoding the information
on the axio-dilaton, the warp factor and the NS-NS and R-R fluxes.Comment: 49 pages, including 22 pages of Appendix, 2 figures. Minor change
Covid-19 and the role of smoking: The protocol of the multicentric prospective study COSMO-IT (covid19 and smoking in italy)
The emergency caused by Covid-19 pandemic raised interest in studying lifestyles and comorbidities as important determinants of poor Covid-19 prognosis. Data on tobacco smoking, alcohol consumption and obesity are still limited, while no data are available on the role of e-cigarettes and heated tobacco products (HTP). To clarify the role of tobacco smoking and other lifestyle habits on COVID-19 severity and progression, we designed a longitudinal observational study titled COvid19 and SMOking in ITaly (COSMO-IT). About 30 Italian hospitals in North, Centre and South of Italy joined the study. Its main aims are: 1) to quantify the role of tobacco smoking and smoking cessation on the severity and progression of COVID-19 in hospitalized patients; 2) to compare smoking prevalence and severity of the disease in relation to smoking in hospitalized COVID-19 patients versus patients treated at home; 3) to quantify the association between other lifestyle factors, such as e-cigarette and HTP use, alcohol and obesity and the risk of unfavourable COVID-19 outcomes. Socio-demographic, lifestyle and medical history information will be gathered for around 3000 hospitalized and 700-1000 home-isolated, laboratory-confirmed, COVID-19 patients. Given the current absence of a vaccine against SARS-COV-2 and the lack of a specific treatment for COVID-19, prevention strategies are of extreme importance. This project, designed to highly contribute to the international scientific debate on the role of avoidable lifestyle habits on COVID-19 severity, will provide valuable epidemiological data in order to support important recommendations to prevent COVID-19 incidence, progression and mortality