364 research outputs found
Localization and traces in open-closed topological Landau-Ginzburg models
We reconsider the issue of localization in open-closed B-twisted
Landau-Ginzburg models with arbitrary Calabi-Yau target. Through careful
analsysis of zero-mode reduction, we show that the closed model allows for a
one-parameter family of localization pictures, which generalize the standard
residue representation. The parameter which indexes these pictures
measures the area of worldsheets with topology, with the residue
representation obtained in the limit of small area. In the boundary sector, we
find a double family of such pictures, depending on parameters and
which measure the area and boundary length of worldsheets with disk
topology. We show that setting and varying interpolates
between the localization picture of the B-model with a noncompact target space
and a certain residue representation proposed recently. This gives a complete
derivation of the boundary residue formula, starting from the explicit
construction of the boundary coupling. We also show that the various
localization pictures are related by a semigroup of homotopy equivalences.Comment: 36 page
On the boundary coupling of topological Landau-Ginzburg models
I propose a general form for the boundary coupling of B-type topological
Landau-Ginzburg models. In particular, I show that the relevant background in
the open string sector is a (generally non-Abelian) superconnection of type
(0,1) living in a complex superbundle defined on the target space, which I
allow to be a non-compact Calabi-Yau manifold. This extends and clarifies
previous proposals. Generalizing an argument due to Witten, I show that BRST
invariance of the partition function on the worldsheet amounts to the condition
that the (0,<= 2) part of the superconnection's curvature equals a constant
endomorphism plus the Landau-Ginzburg potential times the identity section of
the underlying superbundle. This provides the target space equations of motion
for the open topological model.Comment: 21 page
Collapsing D-branes in one-parameter models and small/large radius duality
We finalize the study of collapsing D-branes in one-parameter models by
completing the analysis of the associated hypergeometric hierarchy. This brings
further evidence that the phenomenon of collapsing 6-branes at the mirror of
the `conifold' point in IIA compactifications on one-parameter Calabi-Yau
manifolds is generic. It also completes the reduction of the study of higher
periods in one-parameter models to a few families which display characteristic
behaviour. One of the models we consider displays an exotic form of small-large
radius duality, which is a consequence of an ``accidental'' discrete symmetry
of its moduli space. We discuss the implementation of this symmetry at the
level of the associated type II string compactification and its action on
D-brane states. We also argue that this model admits two special Lagrangian
fibrations and that the symmetry can be understood as their exchange.Comment: 34 pages, 12 figure
Collapsing D-Branes in Calabi-Yau Moduli Space: I
We study the quantum volume of D-branes wrapped around various cycles in
Calabi-Yau manifolds, as the manifold's moduli are varied. In particular, we
focus on the behaviour of these D-branes near phase transitions between
distinct low energy physical descriptions of the resulting string theory.
Whereas previous studies have solely considered quantum volumes in the context
of two-cycles in perturbative string theory or D-branes in the specific example
of the quintic hypersurface, we work more generally and find qualitatively new
features. On the mathematical side, as we briefly note, our work has some
interesting implications for certain issues in arithmetics.Comment: 77 pages, 15 figure
Thomson and Compton scattering with an intense laser pulse
Our paper concerns the scattering of intense laser radiation on free
electrons and it is focused on the relation between nonlinear Compton and
nonlinear Thomson scattering. The analysis is performed for a laser field
modeled by an ideal pulse with a finite duration, a fixed direction of
propagation and indefinitely extended in the plane perpendicular to it. We
derive the classical limit of the quantum spectral and angular distribution of
the emitted radiation, for an arbitrary polarization of the laser pulse. We
also rederive our result directly, in the framework of classical
electrodynamics, obtaining, at the same time, the distribution for the emitted
radiation with a well defined polarization. The results reduce to those
established by Krafft et al. [Phys. Rev. E 72, 056502 (2005)] in the particular
case of linear polarization of the pulse, orthogonal to the initial electron
momentum. Conditions in which the differences between classical and quantum
results are visible are discussed and illustrated by graphs
Cardy condition for open-closed field algebras
Let be a vertex operator algebra satisfying certain reductivity and
finiteness conditions such that , the category of V-modules, is
a modular tensor category. We study open-closed field algebras over V equipped
with nondegenerate invariant bilinear forms for both open and closed sectors.
We show that they give algebras over certain \C-extension of the Swiss-cheese
partial dioperad, and we obtain Ishibashi states easily in such algebras. We
formulate Cardy condition algebraically in terms of the action of the modular
transformation on the space of intertwining
operators. We then derive a graphical representation of S in the modular tensor
category . This result enables us to give a categorical
formulation of Cardy condition and modular invariant conformal full field
algebra over . Then we incorporate the modular invariance condition
for genus-one closed theory, Cardy condition and the axioms for open-closed
field algebra over V equipped with nondegenerate invariant bilinear forms into
a tensor-categorical notion called Cardy -algebra. We also give a categorical construction of Cardy
-algebra in Cardy case.Comment: 70 page, 105 figures, references are updated. less typos, to appear
in Comm. Math. Phy
Global Search for New Physics with 2.0/fb at CDF
Data collected in Run II of the Fermilab Tevatron are searched for
indications of new electroweak-scale physics. Rather than focusing on
particular new physics scenarios, CDF data are analyzed for discrepancies with
the standard model prediction. A model-independent approach (Vista) considers
gross features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided by two additional
algorithms: a Bump Hunter searches invariant mass distributions for "bumps"
that could indicate resonant production of new particles; and the Sleuth
procedure scans for data excesses at large summed transverse momentum. This
combined global search for new physics in 2.0/fb of ppbar collisions at
sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D
Rapid Communication
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020
We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe
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