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تسجيل مستخدم جديدProject {tt SANC} (former {tt CalcPHEP}): Support of Analytic and Numeric calculations for experiments at Colliders
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The project, aimed at the theoretical support of experiments at modern and future accelerators -- TEVATRON, LHC, electron Linear Colliders (TESLA, NLC, CLIC) and muon factories, is presented. Within this project a four-level computer system is being created, which must automatically calculate, at the one-loop precision level the pseudo- and realistic observables (decay rates and event distributions) for more and more complicated processes of elementary particle interaction, using the principle of knowledge storing. It was already used for a recalculation of the EW radiative corrections for Atomic Parity Violation [1] and complete one-loop corrections for the process $e^+ e^-to tbar{t}$ [2-4]; for the latter an, agreement up to 11 digits with FeynArts and the other results is found. The version of {tt SANC} that we describe here is capable of automatically computing the decay rates and the distributions for the decays $Z(H,W)to fbar{f}$ in the one-loop approximation.
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In this paper we describe the present status and our plans for the realization of next phases of the CalcPHEP project aimed at the theoretical support of experiments at modern and future accelerators: TEVATRON, LHC, electron Linear Colliders (LCs) i.
e. TESLA, NLC, CLIC, and muon factories. Within this project, we are creating a four-level computer system which eventually must automatically calculate pseudo- and realistic observables for more and more complicated processes of elementary particle interactions, using the principle of knowledge storing. The first phase of the CalcPHEP system was realized in the site http://brg.jinr.ru/ in 2000--2001.
The work presented here attempts at answering the question: how do we decide when a given adetection is a planet or just residual noise in exoplanet direct imaging data? To this end we present a method implemented within a Bayesian framework: (1) to
unify source detection, and, source characterization into one single rigorous mathematical framework; (2) to enable an adequate hypothesis testing given the S/N of the data; (3) to enhance the detectability of planets faint signal in the presence of instrumental and background noise and to optimize the characterization of the planet. As a proof of concept we implemented a routine named ${tt PlanetEvidence}$ that integrates the nested sampling technique (Multinest) with a post-processing technique, the Karhunen-Loeve Image Processing (KLIP), algorithm. This is a first step to recast such post-processing method into a fully Bayesian perspective. We test our approach on real direct imaging data, specifically using GPI data of $beta$ Pictoris b, and, on synthetic data. We find that for the former the method strongly favors the presence of a planet (as expected) and recovers the true parameter posterior distributions. While for the latter case our approach allows us to detect (true) dim sources invisible to the naked eye as real planets, rather than background noise, and set a new lower threshold for detection at the 2$sigma$ level approximately. Further it allows us to quantify our confidence that a given detection is a real planet and not just residual noise (for example residual speckles). The next natural step is to extend this approach to construct a Bayesian-based algorithm for blind detection, that is, not requiring an initial guess as to the location of the planet. This is the subject of ongoing work.
The TT-PET collaboration is developing a small animal TOF-PET scanner based on monolithic silicon pixel sensors in SiGe BiCMOS technology. The demonstrator chip, a small-scale version of the final detector ASIC, consists of a 3 x 10 pixel matrix inte
grated with the front-end, a 50 ps binning TDC and read out logic. The chip, thinned down to 100 {mu}m and backside metallized, was operated at a voltage of 180 V. The tests on a beam line of minimum ionizing particles show a detection efficiency greater than 99.9 % and a time resolution down to 110 ps.
We present an analysis of 12 optically selected dual AGN candidates at $z < 0.34$. Each candidate was originally identified via double-peaked [O III] $lambda$5007 emission lines, and have received follow-up $Chandra$ and $HST$ observations. Because t
he X-ray data are low-count ($<100$ counts) with small separations ($<1$), a robust analysis is necessary for classifying each source. Pairing long-slit [O III] observations with existing $Chandra$ observations, we re-analyze the X-ray observations with ${tt BAYMAX}$ to determine whether the X-ray emission from each system is more likely a single or dual point source. We find that 4 of the 12 sources are likely dual X-ray point source systems. We examine each point sources spectra via a Monte Carlo method that probabilistically identifies the likely origin of each photon. When doing so, we find that (i) the secondary X-ray point sources in 2 of the systems have $L_{mathrm{X}}<10^{40}$ erg s$^{-1}$, such that we cannot rule out a non-AGN origin, (ii) one source has a secondary with $L_{mathrm{X}}>10^{40}$ erg s$^{-1}$ but a spectrum that is too soft to definitively preclude being X-ray emitting diffuse gas that was photoionized by the primary AGN, and (iii) one system (SDSS J1126+2944) is a dual AGN. Additionally, using complementary $HST$ observations, we analyze a sub-sample of systems that are visually identified as merging. Our results suggest that dual AGNs may preferentially reside in mergers with small separations, consistent with both simulations and observations.
The tt* equation that we will study here is classed as case 4a by Guest et al. in their series of papers Isomomodromy aspects of the tt* equations of Cecotti and Vafa. In their comprehensive works, Guest et al. give a lot of beautiful formulas on and
finally achieve a complete picture of asymptotic data, Stokes data and holomorphic data. But, some of their formulas are complicated, lacking of intuitional explanation or other relevant results that could directly support them. In this paper, we will first verify numerically their formulas among the asymptotic data and Stokes data. Then, we will enlarge the solution class assumed by Guest et al. from the Stoke data side. Based on the numerical results, we put forward a conjecture on the enlarged class of solutions. At last, some trial to enlarge the solution class from the asymptotic data are done. It is the truncation structure of the tt* equation that enables us to do those numerical studies with a satisfactory high precision.
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