1,212 research outputs found
Gopakumar-Vafa invariants via vanishing cycles
In this paper, we propose an ansatz for defining Gopakumar-Vafa invariants of
Calabi-Yau threefolds, using perverse sheaves of vanishing cycles. Our proposal
is a modification of a recent approach of Kiem-Li, which is itself based on
earlier ideas of Hosono-Saito-Takahashi. We conjecture that these invariants
are equivalent to other curve-counting theories such as Gromov-Witten theory
and Pandharipande-Thomas theory. Our main theorem is that, for local surfaces,
our invariants agree with PT invariants for irreducible one-cycles. We also
give a counter-example to the Kiem-Li conjectures, where our invariants match
the predicted answer. Finally, we give examples where our invariant matches the
expected answer in cases where the cycle is non-reduced, non-planar, or
non-primitive.Comment: 63 pages, many improvements of the exposition following referee
comments, final version to appear in Inventione
Enumerative geometry of Calabi-Yau 4-folds
Gromov-Witten theory is used to define an enumerative geometry of curves in
Calabi-Yau 4-folds. The main technique is to find exact solutions to moving
multiple cover integrals. The resulting invariants are analogous to the BPS
counts of Gopakumar and Vafa for Calabi-Yau 3-folds. We conjecture the 4-fold
invariants to be integers and expect a sheaf theoretic explanation.
Several local Calabi-Yau 4-folds are solved exactly. Compact cases, including
the sextic Calabi-Yau in CP5, are also studied. A complete solution of the
Gromov-Witten theory of the sextic is conjecturally obtained by the holomorphic
anomaly equation.Comment: 44 page
Gauge theory, topological strings, and S-duality
We offer a derivation of the duality between the topological U(1) gauge
theory on a Calabi-Yau 3-fold and the topological A-model on the same manifold.
This duality was conjectured recently by Iqbal, Nekrasov, Okounkov, and Vafa.
We deduce it from the S-duality of the IIB superstring. We also argue that the
mirror version of this duality relates the topological B-model on a Calabi-Yau
3-fold and a topological sector of the Type IIA Little String Theory on the
same manifold.Comment: 9 pages, latex. v2: a footnote has been added. The footnote corrects
an inaccuracy in the original argument; the results are unchanged. v3:
exposition improve
Comparative Analysis of a Transition Region Bright Point with a Blinker and Coronal Bright Point Using Multiple EIS Emission Lines
Since their discovery twenty year ago, transition region bright points
(TRBPs) have never been observed spectroscopically. Bright point properties
have not been compared with similar transition region and coronal structures.
In this work we have investigated three transient quiet Sun brightenings
including a TRBP, a coronal BP (CBP) and a blinker. We use time-series
observations of the extreme ultraviolet emission lines of a wide range of
temperature T (log T = 5.3 - 6.4) from the EUV imaging spectrometer (EIS)
onboard the Hinode satellite. We present the EIS temperature maps and Doppler
maps, which are compared with magnetograms from the Michelson Doppler Imager
(MDI) onboard the SOHO satellite. Doppler velocities of the TR BP and blinker
are <,25 km s, which is typical of transient TR phenomena. The Dopper
velocities of the CBP were found to be < 20 km s^{-1} with exception of those
measured at log T = 6.2 where a distinct bi-directional jet is observed. From
an EM loci analysis we find evidence of single and double isothermal components
in the TRBP and CBP, respectively. TRBP and CBP loci curves are characterized
by broad distributions suggesting the existence of unresolved structure. By
comparing and contrasting the physical characteristics of the events we find
the BP phenomena are an indication of multi-scaled self similarity, given
similarities in both their underlying magnetic field configuration and
evolution in relation to EUV flux changes. In contrast, the blinker phenomena
and the TRBP are sufficiently dissimilar in their observed properties as to
constitute different event classes. Our work indicates that the measurement of
similar characteristics across multiple event types holds class-predictive
power, and is a significant step towards automated solar atmospheric
multi-class classification of unresolved transient EUV sources.Comment: 38 pages, 16 figure
Direct Integration of the Topological String
We present a new method to solve the holomorphic anomaly equations governing
the free energies of type B topological strings. The method is based on direct
integration with respect to the non-holomorphic dependence of the amplitudes,
and relies on the interplay between non-holomorphicity and modularity
properties of the topological string amplitudes. We develop a formalism valid
for any Calabi-Yau manifold and we study in detail two examples, providing
closed expressions for the amplitudes at low genus, as well as a discussion of
the boundary conditions that fix the holomorphic ambiguity. The first example
is the non-compact Calabi-Yau underlying Seiberg-Witten theory and its
gravitational corrections. The second example is the Enriques Calabi-Yau, which
we solve in full generality up to genus six. We discuss various aspects of this
model: we obtain a new method to generate holomorphic automorphic forms on the
Enriques moduli space, we write down a new product formula for the fiber
amplitudes at all genus, and we analyze in detail the field theory limit. This
allows us to uncover the modularity properties of SU(2), N=2 super Yang-Mills
theory with four massless hypermultiplets.Comment: 75 pages, 3 figure
Drug use in acute otitis media: a prospective study at a tertiary care teaching hospital
Background: Drug use study identifies the problems that arise from prescription and highlights the current approaches to the rational use of drugs. The objective of the study was to assess drug use pattern in patients diagnosed of acute otitis media in tertiary care teaching hospital.Methods: This prospective observational study was carried in the Otorhinolaryngology department of a tertiary care teaching hospital over a period of twelve months. The data collected for patients with acute otitis media included the patient's demographic details and the drugs prescribed. Data were analysed for drug use pattern and cost per prescription and assessment of rationality of prescription.Results: Total 153 patients were analysed, 100 (65.35%) belonged to male patients and 53 (34.65%) belonged to female patients. Children less than 2years age were the most diagnosed with AOM 47.71%, the major diagnostic symptoms were earache (58.16%) and fever (54.90%) and signs were congestion (52.94%) and discharge (43.13%). In a total 153 prescriptions (469 drugs), 33.68% were antimicrobials, followed by mineral supplements (23.67%). Average number of drugs per prescription was found to be 3.0. Most common antibiotic prescribed was amoxicillin (with or without clavulanate) in 142 (92.81%) patients. Paracetamol alone or in fixed dose combination with antihistaminics were prescribed in 131 patients. Average cost per prescription was 87.74(±35.67) Indian rupees. Seventeen (11.11%) prescriptions were rational in all the aspects based on standard guidelines.Conclusions: The present study showed that paracetamol and amoxicillin with or without clavulanate were mostly commonly prescribed in children with AOM. Irrational prescribing was seen in maximum number of cases
Holomorphic anomaly equations and the Igusa cusp form conjecture
Let be a K3 surface and let be an elliptic curve. We solve the
reduced Gromov-Witten theory of the Calabi-Yau threefold for all
curve classes which are primitive in the K3 factor. In particular, we deduce
the Igusa cusp form conjecture.
The proof relies on new results in the Gromov-Witten theory of elliptic
curves and K3 surfaces. We show the generating series of Gromov-Witten classes
of an elliptic curve are cycle-valued quasimodular forms and satisfy a
holomorphic anomaly equation. The quasimodularity generalizes a result by
Okounkov and Pandharipande, and the holomorphic anomaly equation proves a
conjecture of Milanov, Ruan and Shen. We further conjecture quasimodularity and
holomorphic anomaly equations for the cycle-valued Gromov-Witten theory of
every elliptic fibration with section. The conjecture generalizes the
holomorphic anomaly equations for ellliptic Calabi-Yau threefolds predicted by
Bershadsky, Cecotti, Ooguri, and Vafa. We show a modified conjecture holds
numerically for the reduced Gromov-Witten theory of K3 surfaces in primitive
classes.Comment: 68 page
Topological wave functions and heat equations
It is generally known that the holomorphic anomaly equations in topological
string theory reflect the quantum mechanical nature of the topological string
partition function. We present two new results which make this assertion more
precise: (i) we give a new, purely holomorphic version of the holomorphic
anomaly equations, clarifying their relation to the heat equation satisfied by
the Jacobi theta series; (ii) in cases where the moduli space is a Hermitian
symmetric tube domain , we show that the general solution of the anomaly
equations is a matrix element \IP{\Psi | g | \Omega} of the
Schr\"odinger-Weil representation of a Heisenberg extension of , between an
arbitrary state and a particular vacuum state .
Based on these results, we speculate on the existence of a one-parameter
generalization of the usual topological amplitude, which in symmetric cases
transforms in the smallest unitary representation of the duality group in
three dimensions, and on its relations to hypermultiplet couplings, nonabelian
Donaldson-Thomas theory and black hole degeneracies.Comment: 50 pages; v2: small typos fixed, references added; v3: cosmetic
changes, published version; v4: typos fixed, small clarification adde
Strengthening the Cohomological Crepant Resolution Conjecture for Hilbert-Chow morphisms
Given any smooth toric surface S, we prove a SYM-HILB correspondence which
relates the 3-point, degree zero, extended Gromov-Witten invariants of the
n-fold symmetric product stack [Sym^n(S)] of S to the 3-point extremal
Gromov-Witten invariants of the Hilbert scheme Hilb^n(S) of n points on S. As
we do not specialize the values of the quantum parameters involved, this result
proves a strengthening of Ruan's Cohomological Crepant Resolution Conjecture
for the Hilbert-Chow morphism from Hilb^n(S) to Sym^n(S) and yields a method of
reconstructing the cup product for Hilb^n(S) from the orbifold invariants of
[Sym^n(S)].Comment: Revised versio
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