3,830 research outputs found
Open Gromov-Witten Invariants of Toric Calabi-Yau 3-Folds
We present a proof of the mirror conjecture of Aganagic-Vafa
[arXiv:hep-th/0012041] and Aganagic-Klemm-Vafa [arXiv:hep-th/0105045] on disk
enumeration in toric Calabi-Yau 3-folds for all smooth semi-projective toric
Calabi-Yau 3-folds. We consider both inner and outer branes, at arbitrary
framing. In particular, we recover previous results on the conjecture for (i)
an inner brane at zero framing in the total space of the canonical line bundle
of the projective plane (Graber-Zaslow [arXiv:hep-th/0109075]), (ii) an outer
brane at arbitrary framing in the resolved conifold (Zhou [arXiv:1001.0447]),
and (iii) an outer brane at zero framing in the total space of the canonical
line bundle of the projective plane (Brini [arXiv:1102.0281, Section 5.3]).Comment: 39 pages, 11 figure
Optical quenching and recovery of photoconductivity in single-crystal diamond
We study the photocurrent induced by pulsed-light illumination (pulse
duration is several nanoseconds) of single-crystal diamond containing nitrogen
impurities. Application of additional continuous-wave light of the same
wavelength quenches pulsed photocurrent. Characterization of the optically
quenched photocurrent and its recovery is important for the development of
diamond based electronics and sensing
Unusual statistics of interference effects in neutron scattering from compound nuclei
We consider interference effects between p-wave resonance scattering
amplitude and background s-wave amplitude in low-energy neutron scattering from
a heavy nucleus which goes through the compound nucleus stage. The first effect
is in the difference between the forward and backward scattering cross
sections. Because of the chaotic nature of the compound states, this effect is
a random variable with zero mean. However, a statistical consideration shows
that the probability distribution of this effect does not obey the standard
central limit theorem. That is, the probability density for the effect averaged
over n resonances does not become a Gaussian distribution with the variance
decreasing as 1/sqrt(n) (``violation'' of the theorem!). We derive the
probability distribution of the effect and the limit distribution of the
average. It is found that the width of this distribution does not decrease with
the increase of n, i.e., fluctuations are not suppressed by averaging.
Furthermore, we consider the correlation between the neutron spin and the
scattering plane and find that this effect, although much smaller, shows
fluctuations which actually increase upon averaging over many measurements.
Limits of the effects due to finite resonance widths are also considered. In
the appendix we present a simple derivation of the limit theorem for the
average of random variables with infinite variances.Comment: 15 pages, RevTeX, submitted to Phys. Rev.
Knowledge Graph Completion via Complex Tensor Factorization
In statistical relational learning, knowledge graph completion deals with automatically
understanding the structure of large knowledge graphs—labeled directed graphs—and predicting missing relationships—labeled edges. State-of-the-art embedding models
propose different trade-offs between modeling expressiveness, and time and space complexity.
We reconcile both expressiveness and complexity through the use of complex-valued
embeddings and explore the link between such complex-valued embeddings and unitary
diagonalization. We corroborate our approach theoretically and show that all real square
matrices—thus all possible relation/adjacency matrices—are the real part of some unitarily
diagonalizable matrix. This results opens the door to a lot of other applications of square
matrices factorization. Our approach based on complex embeddings is arguably simple,
as it only involves a Hermitian dot product, the complex counterpart of the standard dot
product between real vectors, whereas other methods resort to more and more complicated
composition functions to increase their expressiveness. The proposed complex embeddings
are scalable to large data sets as it remains linear in both space and time, while consistently
outperforming alternative approaches on standard link prediction benchmarks
Spin constrained orbital angular momentum control in high-harmonic generation
The interplay between spin and orbital angular momentum in the up-conversion
process allows us to control the macroscopic wave front of high harmonics by
manipulating the microscopic polarizations of the driving field. We demonstrate
control of orbital angular momentum in high harmonic generation from both solid
and gas phase targets using the selection rules of spin angular momentum. The
gas phase harmonics extend the control of angular momentum to
extreme-ultraviolet wavelength. We also propose a bi-color scheme to produce
spectrally separated extreme-ultraviolet radiation carrying orbital angular
momentum
Novel critical exponent of magnetization curves near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3 (A = Ca, La0.5Na0.5, and La)
We report a novel critical exponent delta=3/2 of magnetization curves
M=H^{1/delta} near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3
(A = Ca, La0.5Na0.5, and La), which the mean field theory of the
Ginzburg-Landau-Wilson type fails to reproduce. The effect of dirty
ferromagnetic spin fluctuations might be a key.Comment: 4 pages, 5 figure
Neutral B-meson mixing from three-flavor lattice QCD: Determination of the SU(3)-breaking ratio \xi
We study SU(3)-breaking effects in the neutral B_d-\bar B_d and B_s-\bar B_s
systems with unquenched N_f=2+1 lattice QCD. We calculate the relevant matrix
elements on the MILC collaboration's gauge configurations with asqtad-improved
staggered sea quarks. For the valence light-quarks (u, d, and s) we use the
asqtad action, while for b quarks we use the Fermilab action. We obtain
\xi=f_{B_s}\sqrt{B_{B_s}}/f_{B_d}\sqrt{B_{B_d}}=1.268+-0.063. We also present
results for the ratio of bag parameters B_{B_s}/B_{B_d} and the ratio of CKM
matrix elements |V_{td}|/|V_{ts}|. Although we focus on the calculation of \xi,
the strategy and techniques described here will be employed in future extended
studies of the B mixing parameters \Delta M_{d,s} and \Delta\Gamma_{d,s} in the
Standard Model and beyond.Comment: 36 pages, 7 figure
Levels of protein C and soluble thrombomodulin in critically ill patients with acute kidney injury: a multicenter prospective observational study.
Endothelial dysfunction contributes to the development of acute kidney injury (AKI) in animal models of ischemia reperfusion injury and sepsis. There are limited data on markers of endothelial dysfunction in human AKI. We hypothesized that Protein C (PC) and soluble thrombomodulin (sTM) levels could predict AKI. We conducted a multicenter prospective study in 80 patients to assess the relationship of PC and sTM levels to AKI, defined by the AKIN creatinine (AKI Scr) and urine output criteria (AKI UO). We measured marker levels for up to 10 days from intensive care unit admission. We used area under the curve (AUC) and time-dependent multivariable Cox proportional hazard model to predict AKI and logistic regression to predict mortality/non-renal recovery. Protein C and sTM were not different in patients with AKI UO only versus no AKI. On intensive care unit admission, as PC levels are usually lower with AKI Scr, the AUC to predict the absence of AKI was 0.63 (95%CI 0.44-0.78). The AUC using log10 sTM levels to predict AKI was 0.77 (95%CI 0.62-0.89), which predicted AKI Scr better than serum and urine neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C, urine kidney injury molecule-1 and liver-fatty acid-binding protein. In multivariable models, PC and urine NGAL levels independently predicted AKI (p=0.04 and 0.02) and PC levels independently predicted mortality/non-renal recovery (p=0.04). In our study, PC and sTM levels can predict AKI Scr but are not modified during AKI UO alone. PC levels could independently predict mortality/non-renal recovery. Additional larger studies are needed to define the relationship between markers of endothelial dysfunction and AKI
Wall-crossing, open BPS counting and matrix models
We consider wall-crossing phenomena associated to the counting of D2-branes
attached to D4-branes wrapping lagrangian cycles in Calabi-Yau manifolds, both
from M-theory and matrix model perspective. Firstly, from M-theory viewpoint,
we review that open BPS generating functions in various chambers are given by a
restriction of the modulus square of the open topological string partition
functions. Secondly, we show that these BPS generating functions can be
identified with integrands of matrix models, which naturally arise in the free
fermion formulation of corresponding crystal models. A parameter specifying a
choice of an open BPS chamber has a natural, geometric interpretation in the
crystal model. These results extend previously known relations between open
topological string amplitudes and matrix models to include chamber dependence.Comment: 25 pages, 8 figures, published versio
- …