point correlation
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Author(s):  
Siddharth Mishra-Sharma

Abstract Astrometry---the precise measurement of positions and motions of celestial objects---has emerged as a promising avenue for characterizing the dark matter population in our Galaxy. By leveraging recent advances in simulation-based inference and neural network architectures, we introduce a novel method to search for global dark matter-induced gravitational lensing signatures in astrometric datasets. Our method based on neural likelihood-ratio estimation shows significantly enhanced sensitivity to a cold dark matter population and more favorable scaling with measurement noise compared to existing approaches based on two-point correlation statistics, establishing machine learning as a powerful tool for characterizing dark matter using astrometric data.


Author(s):  
Alex Gough ◽  
Cora Uhlemann

The late universe contains a wealth of information about fundamental physics and gravity, wrapped up in non-Gaussian fields. To make use of as much information as possible it is necessary to go beyond two-point statistics. Rather than going to higher order N-point correlation functions, we demonstrate that the probability distribution function (PDF) of spheres in the matter field (a one-point function) already contains a significant amount of this non-Gaussian information. The matter PDF dissects different density environments which are lumped together in two-point statistics, making it particularly useful for probing modifications of gravity or expansion history. Our approach in Cataneo et. al. 2021 extends the success of Large Deviation Theory for predicting the matter PDF in ΛCDM in these “extended” cosmologies. A Fisher forecast demonstrates the information content in the matter PDF via constraints for a Euclid-like survey volume combining the 3D matter PDF with the 3D matter power spectrum. Adding the matter PDF halves the uncertainties on parameters in an evolving dark energy model, relative to the power spectrum alone. Additionally, the matter PDF contains enough non-linear information to substantially increase the detection significance of departures from General Relativity, with improvements up to six times the power spectrum alone. This analysis demonstrates that the matter PDF is a promising non-Gaussian statistic for extracting cosmological information, particularly for beyond ΛCDM models.


2021 ◽  
Vol 1 (2) ◽  
pp. 163-169
Author(s):  
UCI NURHAYATI

The purpose of this study was to determine the differences in students' mathematics learning outcomes who were taught using the STAD learning model and the TGT learning model on triangles and quadrilaterals (In Grade VII Even Semester 2014-2015 Academic Year at SMP Muhammadiyah 31 East Jakarta). The method used is the experimental method. The material tested is about triangles and quadrilaterals. Before being used to collect respondent data, a test test was carried out first and the validity was calculated using the Biserial Point Correlation (rpbis). Calculation of the validity of the instrument on triangle and quadrilateral material obtained 26 valid questions and 14 invalid questions, while the reliability was calculated with KR-20 which was 0.948. It means that the reliability is high. Based on the calculations obtained data that the average student learning outcomes through the STAD learning model has an average of 61.70 standard deviations, 11.06 medians, 64.6 and the mode is 61. Furthermore, the TGT learning model has an average of 71.84 standard deviations of 12, 01 median 78 and mode 64. Hypothesis testing using t-test is obtained t = 2.98 at a significant level of 0.05 and dk = 46 t = 1.67 because t t is 2.98 1.67 so it can be concluded that there are differences in the mathematics learning outcomes of students who are taught using the STAD learning model and the TGT learning model in solving problems on triangle and quadrilateral material. ABSTRAKTujuan dari penelitian ini adalah untuk mengetahui adanya Perbedaan hasil belajar matematika peserta didik yang diajarkan menggunakan model pembelajaran STAD dan model pembelajaran TGT pada materi segitiga dan segiempat (Di kelas VII Semester Genap Tahun Pelajaran 2014-2015 Di SMP Muhammadiyah 31 Jakarta Timur). Metode yang digunakan adalah metode eksperimen. Materi yang diujikan tentang materi segitiga dan segiempat. Sebelum dipergunakan untuk mengambil data responden dilakukan terlebih dahulu uji coba soal dan dihitung validitasnya dengan Korelasi Point Biserial (rpbis). Perhitungan validitas instrument pada materi segitiga dan segiempat diperoleh 26 soal yang valid dan 14 soal yang tidak valid sedangkan reliabilitasnya dihitung dengan KR-20 yaitu 0,948. Berarti reliabelitas tergolong tinggi. Berdasarkan perhitungan diperoleh data bahwa rata-rata hasil belajar siswa melalui model pembelajaran STAD memiliki rata-rata 61,70 simpangan baku 11,06 median 64,6 serta modusnya 61. Selanjutnya model pembelajaran TGT memiliki rata-rata 71,84 simpangan baku 12,01 median 78 serta modusnya 64. Uji hipotesis menggunakan uji-t di peroleh t  = 2,98 pada taraf signifikan 0,05 dan dk = 46 t  = 1,67 karena t  ? t  yaitu 2,98 ? 1,67 sehingga dapat disimpulkan bahwa terdapat perbedaan hasil belajar matematika peserta didik yang diajarkan menggunakan model pembelajaran STAD dan model pembelajaran TGT dalam menyelesaikan soal-soal pada materi segitiga dan segiempat.


Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2309
Author(s):  
Alexei D. Kiselev ◽  
Ranim Ali ◽  
Andrei V. Rybin

In this communication we study dynamics of the open quantum bosonic system governed by the generalized Lindblad equation with both dynamical and environment induced intermode couplings taken into account. By using the method of characteristics we deduce the analytical expression for the normally ordered characteristic function. Analytical results for one-point correlation functions describing temporal evolution of the covariance matrix are obtained.


2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Zhi-Peng Xing ◽  
Zhen-Xing Zhao

AbstractA comprehensive study of $$b\rightarrow c$$ b → c weak decays of doubly heavy baryons is presented in this paper. The transition form factors as well as the pole residues of the initial and final states are respectively obtained by investigating the three-point and two-point correlation functions in QCD sum rules. Contributions from up to dimension-6 operators are respectively considered for the two-point and three-point correlation functions. The obtained form factors are then applied to a phenomenological analysis of semi-leptonic decays.


2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Sachin Jain ◽  
Renjan Rajan John

Abstract In this paper we relate the parity-odd part of two and three point correlation functions in theories with exactly conserved or weakly broken higher spin symmetries to the parity-even part which can be computed from free theories. We also comment on higher point functions.The well known connection of CFT correlation functions with de-Sitter amplitudes in one higher dimension implies a relation between parity-even and parity-odd amplitudes calculated using non-minimal interactions such as $$ {\mathcal{W}}^3 $$ W 3 and $$ {\mathcal{W}}^2\tilde{\mathcal{W}} $$ W 2 W ˜ . In the flat-space limit this implies a relation between parity-even and parity-odd parts of flat-space scattering amplitudes.


Author(s):  
David Montenegro

In this paper, we give an update on divergent problems concerning the radiative corrections of quantum electrodynamics in (3[Formula: see text]+[Formula: see text]1) dimensions. In doing so, we introduce a geometric adaptation for the covariant photon propagator by including a higher derivative field. This derivation, so-called generalized quantum electrodynamics, is motivated by the stability and unitarity features. This theory provides a natural and self-consistent extension of the quantum electrodynamics by enlarging the space parameter of spinor-gauge interactions. In particular, Haag’s theorem undermines the perturbative characterization of the interaction picture due to its inconsistency on quantum field theory foundations. To circumvent this problem, we develop our perturbative approach in the Heisenberg picture and use it to investigate the behavior of the operator current at one-loop. We find the two- and three-point correlation functions are ultraviolet finite, electron self-energy and vertex corrections, respectively. On the other hand, we also explain how the vacuum polarization remains ultraviolet divergent only at [Formula: see text] order. Finally, we evaluate the anomalous magnetic moment, which allows us to specify a lower bound value for the Podolsky parameter.


2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Nikita Nemkov ◽  
Sylvain Ribault

We revisit the critical two-dimensional Ashkin–Teller model, i.e. the \mathbb{Z}_2ℤ2 orbifold of the compactified free boson CFT at c=1c=1. We solve the model on the plane by computing its three-point structure constants and proving crossing symmetry of four-point correlation functions. We do this not only for affine primary fields, but also for Virasoro primary fields, i.e. higher twist fields and degenerate fields. This leads us to clarify the analytic properties of Virasoro conformal blocks and fusion kernels at c=1c=1. We show that blocks with a degenerate channel field should be computed by taking limits in the central charge, rather than in the conformal dimension. In particular, Al. Zamolodchikov’s simple explicit expression for the blocks that appear in four-twist correlation functions is only valid in the non-degenerate case: degenerate blocks, starting with the identity block, are more complicated generalized theta functions.


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