61 research outputs found
Matrix Models, Argyres-Douglas singularities and double scaling limits
We construct an N=1 theory with gauge group U(nN) and degree n+1 tree level
superpotential whose matrix model spectral curve develops an A_{n+1}
Argyres-Douglas singularity. We evaluate the coupling constants of the
low-energy U(1)^n theory and show that the large N expansion is singular at the
Argyres-Douglas points. Nevertheless, it is possible to define appropriate
double scaling limits which are conjectured to yield four dimensional
non-critical string theories as proposed by Ferrari. In the Argyres-Douglas
limit the n-cut spectral curve degenerates into a solution with n/2 cuts for
even n and (n+1)/2 cuts for odd n.Comment: 31 pages, 1 figure; the expression of the superpotential has been
corrected and the calculation of the coupling constants of the low-energy
theory has been adde
Relating prepotentials and quantum vacua of N=1 gauge theories with different tree-level superpotentials
We consider N=1 supersymmetric U(N) gauge theories with Z_k symmetric
tree-level superpotentials W for an adjoint chiral multiplet. We show that (for
integer 2N/k) this Z_k symmetry survives in the quantum effective theory as a
corresponding symmetry of the effective superpotential W_eff(S_i) under
permutations of the S_i. For W(x)=^W(h(x)) with h(x)=x^k, this allows us to
express the prepotential F_0 and effective superpotential W_eff on certain
submanifolds of the moduli space in terms of an ^F_0 and ^W_eff of a different
theory with tree-level superpotential ^W. In particular, if the Z_k symmetric
polynomial W(x) is of degree 2k, then ^W is gaussian and we obtain very
explicit formulae for F_0 and W_eff. Moreover, in this case, every vacuum of
the effective Veneziano-Yankielowicz superpotential ^W_eff is shown to give
rise to a vacuum of W_eff. Somewhat surprisingly, at the level of the
prepotential F_0(S_i) the permutation symmetry only holds for k=2, while it is
anomalous for k>2 due to subtleties related to the non-compact period
integrals. Some of these results are also extended to general polynomial
relations h(x) between the tree-level superpotentials.Comment: 27 pages, 10 figures, modified version to appear in JHEP, discussion
of the physical meaning of the Z_k symmetry adde
Remarks on the analytic structure of supersymmetric effective actions
We study the effective superpotential of N=1 supersymmetric gauge theories
with a mass gap, whose analytic properties are encoded in an algebraic curve.
We propose that the degree of the curve equals the number of semiclassical
branches of the gauge theory. This is true for supersymmetric QCD with one
adjoint and polynomial superpotential, where the two sheets of its
hyperelliptic curve correspond to the gauge theory pseudoconfining and higgs
branches. We verify this proposal in the new case of supersymmetric QCD with
two adjoints and superpotential V(X)+XY^2, which is the confining phase
deformation of the D_{n+2} SCFT. This theory has three kinds of classical vacua
and its curve is cubic. Each of the three sheets of the curve corresponds to
one of the three semiclassical branches of the gauge theory. We show that one
can continuously interpolate between these branches by varying the couplings
along the moduli space.Comment: 49 pages, 3 figures, harvmac; typos correcte
Phases and geometry of the N=1 A_2 quiver gauge theory and matrix models
We study the phases and geometry of the N=1 A_2 quiver gauge theory using
matrix models and a generalized Konishi anomaly. We consider the theory both in
the Coulomb and Higgs phases. Solving the anomaly equations, we find that a
meromorphic one-form sigma(z)dz is naturally defined on the curve Sigma
associated to the theory. Using the Dijkgraaf-Vafa conjecture, we evaluate the
effective low-energy superpotential and demonstrate that its equations of
motion can be translated into a geometric property of Sigma: sigma(z)dz has
integer periods around all compact cycles. This ensures that there exists on
Sigma a meromorphic function whose logarithm sigma(z)dz is the differential. We
argue that the surface determined by this function is the N=2 Seiberg-Witten
curve of the theory.Comment: 41 pages, 2 figures, JHEP style. v2: references adde
Solitons in Seiberg-Witten Theory and D-branes in the Derived Category
We analyze the "geometric engineering" limit of a type II string on a
suitable Calabi-Yau threefold to obtain an N=2 pure SU(2) gauge theory. The
derived category picture together with Pi-stability of B-branes beautifully
reproduces the known spectrum of BPS solitons in this case in a very explicit
way. Much of the analysis is particularly easy since it can be reduced to
questions about the derived category of CP1.Comment: 20 pages, LaTex2
Susceptibility of fruits of the 'ValĂŞncia' and 'Natal' sweet orange varieties to Guignardia citricarpa and the influence of the coexistence of healthy and symptomatic fruits
NMR and NQR Fluctuation Effects in Layered Superconductors
We study the effect of thermal fluctuations of the s-wave order parameter of
a quasi two dimensional superconductor on the nuclear spin relaxation rate near
the transition temperature Tc. We consider both the effects of the amplitude
fluctuations and the Berezinskii-Kosterlitz-Thouless (BKT) phase fluctuations
in weakly coupled layered superconductors. In the treatment of the amplitude
fluctuations we employ the Gaussian approximation and evaluate the longitudinal
relaxation rate 1/T1 for a clean s-wave superconductor, with and without pair
breaking effects, using the static pair fluctuation propagator D. The increase
in 1/T1 due to pair breaking in D is overcompensated by the decrease arising
from the single particle Green's functions. The result is a strong effect on
1/T1 for even a small amount of pair breaking. The phase fluctuations are
described in terms of dynamical BKT excitations in the form of pancake
vortex-antivortex (VA) pairs. We calculate the effect of the magnetic field
fluctuations caused by the translational motion of VA excitations on 1/T1 and
on the transverse relaxation rate 1/T2 on both sides of the BKT transitation
temperature T(BKT)<Tc. The results for the NQR relaxation rates depend strongly
on the diffusion constant that governs the motion of free and bound vortices as
well as the annihilation of VA pairs. We discuss the relaxation rates for real
multilayer systems where the diffusion constant can be small and thus increase
the lifetime of a VA pair, leading to an enhancement of the rates. We also
discuss in some detail the experimental feasibility of observing the effects of
amplitude fluctuations in layered s-wave superconductors such as the
dichalcogenides and the effects of phase fluctuations in s- or d-wave
superconductors such as the layered cuprates.Comment: 38 pages, 12 figure
Taxonomic studies of centric diatoms (Diatomeae): unusual nanoplanktonic forms and new records for Brazil
The global burden of cancer attributable to risk factors, 2010–19: a systematic analysis for the Global Burden of Disease Study 2019
BACKGROUND: Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. METHODS: The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk–outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. FINDINGS: Globally, in 2019, the risk factors included in this analysis accounted for 4·45 million (95% uncertainty interval 4·01–4·94) deaths and 105 million (95·0–116) DALYs for both sexes combined, representing 44·4% (41·3–48·4) of all cancer deaths and 42·0% (39·1–45·6) of all DALYs. There were 2·88 million (2·60–3·18) risk-attributable cancer deaths in males (50·6% [47·8–54·1] of all male cancer deaths) and 1·58 million (1·36–1·84) risk-attributable cancer deaths in females (36·3% [32·5–41·3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20·4% (12·6–28·4) and DALYs by 16·8% (8·8–25·0), with the greatest percentage increase in metabolic risks (34·7% [27·9–42·8] and 33·3% [25·8–42·0]). INTERPRETATION: The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden
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