Parton distributions for the LHC

We present updated leading-order, next-to-leading order and next-to-next-to-leading order parton distribution functions (“MSTW 2008”) determined from global analysis of hard-scattering data within the standard framework of leading-twist fixed-order collinear factorisation in the [`(MS)]\overline{\mathrm{MS}} scheme. These parton distributions supersede the previously available “MRST” sets and should be used for the first LHC data taking and for the associated theoretical calculations. New data sets fitted include CCFR/NuTeV dimuon cross sections, which constrain the strange-quark and -antiquark distributions, and Tevatron Run II data on inclusive jet production, the lepton charge asymmetry from W decays and the Z rapidity distribution. Uncertainties are propagated from the experimental errors on the fitted data points using a new dynamic procedure for each eigenvector of the covariance matrix. We discuss the major changes compared to previous MRST fits, briefly compare to parton distributions obtained by other fitting groups, and give predictions for the W and Z total cross sections at the Tevatron and LHC.     

A novel method for identification of cotton contaminants based on machine vision

Foreign matter is easily mixed into cotton during picking, storing, drying, transporting, purchasing, and processing. These contaminants are difficult to remove in the spinning process and can cause yarn breakage, thus reducing efficiency of working. This paper proposed the new method based on machine vision to measure the contaminants in raw cottons. The color images of cottons with contaminants are acquired and divided three channels images. Intensity of illumination of cottons often is unstable because of the driving voltage of light source unsteady. The intensity of illumination of images should be corrected for measuring correction and precision. The Gamma adjustment function was adopted to correct non-uniform illumination for images. Through the experimental contrast, Gamma correction parameter is set as 0.8. The Otsu method is used to segment the image. After images of three channels’ information fusing, the contaminants of cotton samples can be correctly detected and cotton seeds also can be effectively inspected. The false detection ratio of the measuring system is less than 5%. The experimental results show the measuring system can meet with the requirement of the cotton's industry application.     

A complex network model for seismicity based on mutual information

Seismicity is the product of the interaction between the different parts of the lithosphere. Here, we model each part of the Earth as a cell that is constantly communicating its state to its environment. As a neuron is stimulated and produces an output, the different parts of the lithosphere are constantly stimulated by both other cells and the ductile part of the lithosphere, and produce an output in the form of a stress transfer or an earthquake. This output depends on the properties of each part of the Earth’s crust and the magnitude of the inputs. In this study, we propose an approach to the quantification of this communication, with the aid of the Information Theory, and model seismicity as a Complex Network. We have used data from California, and this new approach gives a better understanding of the processes involved in the formation of seismic patterns in that region.     

A complex network model based on the Gnutella protocol

Gnutella is one of the basic protocols for P2P software. In this paper, a novel network model based on Gnutella is introduced. The mechanism of this network is based on resource occupancy and search activities of peers. As for the structure, the power-law exponent of in-degree γ_in≈4.2, the length of the average shortest path 〈l〉=57.74, and the diameter of the network is 156; these topological properties of the proposed structure differ from known results.     

ScannerS: constraining the phase diagram of a complex scalar singlet at the LHC

We present the first version of a new tool to scan the parameter space of generic scalar potentials, ScannerS (Coimbra et al., ScannerS project., 2013). The main goal of ScannerS is to help distinguish between different patterns of symmetry breaking for each scalar potential. In this work we use it to investigate the possibility of excluding regions of the phase diagram of several versions of a complex singlet extension of the Standard Model, with future LHC results. We find that if another scalar is found, one can exclude a phase with a dark matter candidate in definite regions of the parameter space, while predicting whether a third scalar to be found must be lighter or heavier. The first version of the code is publicly available and contains various generic core routines for tree level vacuum stability analysis, as well as implementations of collider bounds, dark matter constraints, electroweak precision constraints and tree level unitarity.     

Image encryption based on new Beta chaotic maps

In this paper, we created new chaotic maps based on Beta function. The use of these maps is to generate chaotic sequences. Those sequences were used in the encryption scheme. The proposed process is divided into three stages: Permutation, Diffusion and Substitution. The generation of different pseudo random sequences was carried out to shuffle the position of the image pixels and to confuse the relationship between the encrypted the original image, so that significantly increasing the resistance to attacks. The acquired results of the different types of analysis indicate that the proposed method has high sensitivity and security compared to previous schemes.     

Systematic event generator tuning for the LHC

In this article we describe Professor, a new program for tuning model parameters of Monte Carlo event generators to experimental data by parameterising the per-bin generator response to parameter variations and numerically optimising the parameterised behaviour. Simulated experimental analysis data is obtained using the Rivet analysis toolkit. This paper presents the Professor procedure and implementation, illustrated with the application of the method to tunes of the Pythia 6 event generator to data from the LEP/SLD and Tevatron experiments. These tunes are substantial improvements on existing standard choices, and are recommended as base tunes for LHC experiments, to be themselves systematically improved upon when early LHC data is available.     

Searching for L-violating supersymmetry at the LHC

The possibility to simulate lepton number violating supersymmetric models has been introduced into the recently updated Pythia event generator, now containing 1278 decay channels of SUSY particles into SM particles via lepton number violating interactions. This generator has been used in combination with the AtlFast detector simulation to study the impact of lepton number violation () on event topologies in the ATLAS detector, and trigger menus designed for -SUSY are proposed based on very general considerations. In addition, a rather preliminary analysis is presented on the possibility for ATLAS to observe a signal above the background in several mSUGRA scenarios, using a combination of primitive cuts and neural networks to optimize the discriminating power between signal and background events over regions of parameter space rather than at individual points. It is found that a discovery is possible roughly for TeV and TeV with an integrated luminosity of 30 fb, corresponding to one year of data taking with the LHC running at “mid-luminosity”, cms. Received: 5 October 2001 / Revised version: 20 November 2001 / Published online: 18 January 2002     

High p_T Higgs signal for the LHC

We show that the broad transverse momentum distribution of the Higgs boson produced by WW fusion can provide a viable way to identify decays at the LHC, if particular kinematical configurations with large rapidity gaps are selected. We estimate the event rate of the signal and of the QCD background. We also discuss Higgs boson detection via the and decay modes. Received: 25 April 2001 / Published online: 29 June 2001     

Prospects for discovering supersymmetry at the LHC

Supersymmetry is one of the best-motivated candidates for physics beyond the standard model that might be discovered at the LHC. There are many reasons to expect that it may appear at the TeV scale, in particular because it provides a natural cold dark-matter candidate. The apparent discrepancy between the experimental measurement of g _μ −2 and the standard-model value calculated using low-energy e ⁺ e ⁻ data favours relatively light sparticles, accessible to the LHC. A global likelihood analysis including this, other electroweak precision observables and B decay observables suggests that the LHC might be able to discover supersymmetry with 1/fb or less of integrated luminosity. The LHC should be able to discover supersymmetry via the classic missing-energy signature, or in alternative phenomenological scenarios. The prospects for discovering supersymmetry at the LHC look very good. CERN-PH-TH/2008-208.     

基于非球面透镜的光分束器设计

 针对目前532 nm波长光的分束技术在光电测控系统（如激光干涉测速）等领域的广泛应用,提出一种光分束器的设计方法,此分束器可将光纤入射的532 nm绿光分成接近等比的多束光（包括一分二、一分三、一分四）。此系统首先用非球面透镜将光纤入射的光束准直,再通过分光片分光后用同样的透镜将光束耦合进光纤,达到了77%的通光效率,附加损耗约1 dB。详细介绍了非球面透镜的设计、分束器的结构、装配及其实验结果,并对实验结果以及研制过程中影响分束器效率的各种因素进行分析。     

The Impact of the LHC on Cosmology

The last 2 years has seen an immense amount of activity and results from the Large Hadron Collider (LHC). Most notable is the discovery of a new particle which may very well be the long sought Higgs boson associated with electroweak symmetry breaking. There have also been many (up to now) unsuccessful searches for new particles associated with supersymmetry. One of the most attractive candidates for dark matter is the lightest supersymmetric particle (LSP). The recent results from the LHC have had a dramatic impact on our expectations for the properties of the LSP. These results can be used to revise expectations for both direct and indirect detection of dark matter.