<Emphasis Type="Italic">B</Emphasis><Stack><Subscript>s</Subscript><Superscript>0</Superscript></Stack> physics at LHCb

The LHCb experiment is in preparation, to be ready for the start of the LHC. The physics which will be performed by LHCb is reviewed, focussing on what can be learnt fromB _s ⁰ mesons.     

LHC俘获腔高次模阻抗及抑制研究

为研究LHC俘获腔高次模阻抗的抑制结果,将频域和时域的方法应用于此腔的高次模阻抗的计算中,对装有4个磁耦合高次模抑制器LHC俘获腔(三维情况)做了抑制前后高次模阻抗的计算,得到了详细的腔的高次模频谱和阻抗抑制结果,由此可判断高次模吸收器的吸收效果和是否满足束流稳定性要求以及证实其设计的合理性.同时,模拟结果也显示引入高次模抑制器后腔中仍有一些阻抗值较高、具有潜在危险的高次模,这已引起高度重视并为今后的实验研究提供了重要信息.本文详细论述了用于LHC俘获腔的高次模阻抗计算的三维方法和高次模抑制的计算结果.     

DJpsiFDC：an event generator for the process gg→J/ψJ/ψ at the LHC

DJpsiFDC is an event generator package for the process gg→J/ψJ/ψ. It generates events for primary leading-order 2→2 processes. The package could generate a Les Houches Event (LHE) document and this could easily be embedded into detector simulation software frameworks. The package is produced in Fortran code.     

Critical comment on the recent microscopic black hole search at the LHC

Recently the CMS Collaboration at the LHC reported “the first direct limit on black hole production at a particle accelerator” using a data sample corresponding to an integrated luminosity of 35 pb−1 of pp collision at a center of mass energy of 7 TeV (Khachatryan et al., 2011) [1]. Even though the result has a strong impact on future searches, the interpretation lacks enough theoretical support. In this Letter, we show that the parameter range which was considered by the CMS Collaboration is actually out of the validity range of semi-classical black hole picture so that the Monte Carlo simulation result which was crucially used in the analysis still needs further solid scientific basis.     

The Effects of Simplest Little Higgs Model on the Spin Correlations in the Top Quark Pair Production at the LHC and ILC

In the simplest little Higgs model (SLH),we study the spin correlations in the top quark pair production at the LHC and ILC.We find that the SLH always suppresses the t spin correlations compared to the SM values.At the LHC,the suppression can be over 10% for mZ′ 750 GeV.The SLH prediction value is outside the 1σ range of the experimental data from ATLAS,and within 1σ range of the experimental data from CMS.At the ILC,the SLH can sizably suppress the t spin correlation for mZ′approaching the center-of-mass energy √s.For example,the maximal suppression can reach-22.5%,-14.5%,and-9.5% for √s=500 GeV,800 GeV,and 1000 GeV,respectively.Therefore,the t spin correlation at the ILC can be a sensitive probe for the SLH.     

Atomic Physics Studies at the Gamma Factory at CERN

The Gamma Factory initiative proposes to develop novel research tools at CERN by producing, accelerating, and storing highly relativistic, partially stripped ion beams in the SPS and LHC storage rings. By exciting the electronic degrees of freedom of the stored ions with lasers, high-energy narrow-band photon beams will be produced by properly collimating the secondary radiation that is peaked in the direction of ions' propagation. Their intensities, up to 10¹⁷ photons per second, will be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting γ–ray energy domain reaching up to 400 MeV. This article reviews opportunities that may be afforded by utilizing the primary beams for spectroscopy of partially stripped ions circulating in the storage ring, as well as the atomic-physics opportunities made possible by the use of the secondary high-energy photon beams. The Gamma Factory will enable ground-breaking experiments in spectroscopy and novel ways of testing fundamental symmetries of nature.     

The Effects of Simplest Little Higgs Model on the Spin Correlations in the Top Quark Pair Production at the LHC and ILC

In the simplest little Higgs model (SLH), we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for m_Z' < 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for m_Z' approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s=500 GeV, 800 GeV, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.