511 research outputs found
Dirac-mode expansion for confinement and chiral symmetry breaking
We develop a manifestly gauge-covariant expansion and projection using the
eigen-mode of the QCD Dirac operator. Applying this method to the Wilson loop
and the Polyakov loop, we perform a direct analysis of the correlation between
confinement and chiral symmetry breaking in SU(3) lattice QCD calculation on
6^4 at beta=5.6 at the quenched level. Notably, the Wilson loop is found to
obey the area law, and the slope parameter corresponding to the string tension
or the confinement force is almost unchanged, even after removing the low-lying
Dirac modes, which are responsible to chiral symmetry breaking. We find also
that the Polyakov loop remains to be almost zero even without the low-lying
Dirac modes, which indicates the Z_3-unbroken confinement phase. These results
indicate that one-to-one correspondence does not hold between confinement and
chiral symmetry breaking in QCD.Comment: 7 pages, 6 figures, Talk given at Conference: Lattice 201
Stokes matrices for the quantum differential equations of some Fano varieties
The classical Stokes matrices for the quantum differential equation of
projective n-space are computed, using multisummation and the so-called
monodromy identity. Thus, we recover the results of D. Guzzetti that confirm
Dubrovin's conjecture for projective spaces. The same method yields explicit
formulas for the Stokes matrices of the quantum differential equations of
smooth Fano hypersurfaces in projective n-space and for weighted projective
spaces.Comment: 20 pages. Introduction has been changed. Small corrections in the
tex
Mirage in Temporal Correlation functions for Baryon-Baryon Interactions in Lattice QCD
Single state saturation of the temporal correlation function is a key
condition to extract physical observables such as energies and matrix elements
of hadrons from lattice QCD simulations. A method commonly employed to check
the saturation is to seek for a plateau of the observables for large Euclidean
time. Identifying the plateau in the cases having nearby states, however, is
non-trivial and one may even be misled by a fake plateau. Such a situation
takes place typically for the system with two or more baryons. In this study,
we demonstrate explicitly the danger from a possible fake plateau in the
temporal correlation functions mainly for two baryons ( and ), and
three and four baryons ( and as well, employing
(2+1)-flavor lattice QCD at GeV on four lattice volumes with
2.9, 3.6, 4.3 and 5.8 fm. Caution is given for drawing conclusion on the
bound , and systems only based on the temporal correlation
functions.Comment: 32 pages, 13 figures, minor corrections, published version, typos
correcte
Mirror Map as Generating Function of Intersection Numbers: Toric Manifolds with Two K\"ahler Forms
In this paper, we extend our geometrical derivation of expansion coefficients
of mirror maps by localization computation to the case of toric manifolds with
two K\"ahler forms. Especially, we take Hirzebruch surfaces F_{0}, F_{3} and
Calabi-Yau hypersurface in weighted projective space P(1,1,2,2,2) as examples.
We expect that our results can be easily generalized to arbitrary toric
manifold.Comment: 45 pages, 2 figures, minor errors are corrected, English is refined.
Section 1 and Section 2 are enlarged. Especially in Section 2, confusion
between the notion of resolution and the notion of compactification is
resolved. Computation under non-zero equivariant parameters are added in
Section
On the Crepant Resolution Conjecture in the Local Case
In this paper we analyze four examples of birational transformations between
local Calabi-Yau 3-folds: two crepant resolutions, a crepant partial
resolution, and a flop. We study the effect of these transformations on
genus-zero Gromov-Witten invariants, proving the
Coates-Corti-Iritani-Tseng/Ruan form of the Crepant Resolution Conjecture in
each case. Our results suggest that this form of the Crepant Resolution
Conjecture may also hold for more general crepant birational transformations.
They also suggest that Ruan's original Crepant Resolution Conjecture should be
modified, by including appropriate "quantum corrections", and that there is no
straightforward generalization of either Ruan's original Conjecture or the
Cohomological Crepant Resolution Conjecture to the case of crepant partial
resolutions. Our methods are based on mirror symmetry for toric orbifolds.Comment: 27 pages. This is a substantially revised and shortened version of my
preprint "Wall-Crossings in Toric Gromov-Witten Theory II: Local Examples";
all results contained here are also proved there. To appear in Communications
in Mathematical Physic
Lagrangian Floer superpotentials and crepant resolutions for toric orbifolds
We investigate the relationship between the Lagrangian Floer superpotentials
for a toric orbifold and its toric crepant resolutions. More specifically, we
study an open string version of the crepant resolution conjecture (CRC) which
states that the Lagrangian Floer superpotential of a Gorenstein toric orbifold
and that of its toric crepant resolution coincide after
analytic continuation of quantum parameters and a change of variables. Relating
this conjecture with the closed CRC, we find that the change of variable
formula which appears in closed CRC can be explained by relations between open
(orbifold) Gromov-Witten invariants. We also discover a geometric explanation
(in terms of virtual counting of stable orbi-discs) for the specialization of
quantum parameters to roots of unity which appears in Y. Ruan's original CRC
["The cohomology ring of crepant resolutions of orbifolds", Gromov-Witten
theory of spin curves and orbifolds, 117-126, Contemp. Math., 403, Amer. Math.
Soc., Providence, RI, 2006]. We prove the open CRC for the weighted projective
spaces using an equality between open
and closed orbifold Gromov-Witten invariants. Along the way, we also prove an
open mirror theorem for these toric orbifolds.Comment: 48 pages, 1 figure; v2: references added and updated, final version,
to appear in CM
Unified ethical principles and an animal research ‘Helsinki’ declaration as foundations for international collaboration
Ethical frameworks are the foundation for any research with humans or nonhuman animals. Human research is
guided by overarching international ethical principles, such as those defined in the Helsinki Declaration by the
World Medical Association. However, for nonhuman animal research, because there are several sets of ethical
principles and national frameworks, it is commonly thought that there is substantial variability in animal
research approaches internationally and a lack of an animal research ‘Helsinki Declaration’, or the basis for one.
We first overview several prominent sets of ethical principles, including the 3Rs, 3Ss, 3Vs, 4Fs and 6Ps. Then
using the 3Rs principles, originally proposed by Russell & Burch, we critically assess them, asking if they can be
Replaced, Reduced or Refined. We find that the 3Rs principles have survived several replacement challenges, and
the different sets of principles (3Ss, 3Vs, 4Fs and 6Ps) are complementary, a natural refinement of the 3Rs and are
ripe for integration into a unified set of principles, as proposed here. We also overview international frameworks
and documents, many of which incorporate the 3Rs, including the Basel Declaration on animal research. Finally,
we propose that the available animal research guidance documents across countries can be consolidated, to
provide a similar structure as seen in the Helsinki Declaration, potentially as part of an amended Basel Declaration on animal research. In summary, we observe substantially greater agreement on and the possibility for
unification of the sets of ethical principles and documents that can guide animal research internationally
Landau-Ginzburg/Calabi-Yau correspondence, global mirror symmetry and Orlov equivalence
We show that the Gromov-Witten theory of Calabi-Yau hypersurfaces matches, in
genus zero and after an analytic continuation, the quantum singularity theory
(FJRW theory) recently introduced by Fan, Jarvis and Ruan following ideas of
Witten. Moreover, on both sides, we highlight two remarkable integral local
systems arising from the common formalism of Gamma-integral structures applied
to the derived category of the hypersurface {W=0} and to the category of graded
matrix factorizations of W. In this setup, we prove that the analytic
continuation matches Orlov equivalence between the two above categories.Comment: 72pages, v2: Appendix B and references added. Typos corrected, v3:
several mistakes corrected, final versio
Excited States in 52Fe and the Origin of the Yrast Trap at I=12+
Excited states in 52Fe have been determined up to spin 10\hbar in the
reaction 28Si + 28Si at 115 MeV by using \gamma-ray spectroscopy methods at the
GASP array. The excitation energy of the yrast 10+ state has been determined to
be 7.381 MeV, almost 0.5 MeV above the well known \beta+-decaying yrast 12+
state, definitely confirming the nature of its isomeric character. The mean
lifetimes of the states have been measured by using the Doppler Shift
Attenuation method. The experimental data are compared with spherical shell
model calculations in the full pf-shell.Comment: 9 pages, RevTeX, 7 figures include
Does Venue of HIV Testing and Results Disclosure in the Context of a Research Study Affect Adolescent Health and Behavior? Results from a Study in Western Kenya
Ethical concerns about risks to minor adolescents participating in HIV prevention research is a barrier to their inclusion. One concern is whether HIV testing and results disclosure venue affects the health and behavior of adolescent participants. We assessed for differential effects on quality of life (QOL), depressive symptoms, and sexual behavior due to (1) testing venue (home or health facility) and (2) test result (HIV-positive, HIV-negative, indeterminate). We collected data at three timepoints (baseline, 2-month follow-up, 12-month follow-up) from 113 Kenyan adolescents aged 15–19 (51% female). We analyzed the data using linear mixed effects models for the QOL and depressive symptoms outcomes and a logistic model for the sexual behavior outcome. Results showed a small mental health benefit for adolescents tested for HIV at a health facility compared with home. There was little evidence that testing venue influenced sexual behavior or that test results moderated the effects of HIV testing across all outcomes. The decision to conduct HIV testing at home or a health facility may not be very consequential for adolescents’ health and behavior. Findings underscore the need to critically examine assumptions about adolescent vulnerability to better promote responsible conduct of HIV prevention research with youth in sub-Saharan Africa
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