Recent Results on B Meson Oscillations

This paper presents recent time-dependent measurements of neutral B meson oscillations. Similar to the $K^0$--$\bar{K}^0$ system, there are two such systems involving the b quark: $B_d^0$--$\bar{B}_d^0$ and $B_s^0$--$\bar{B}_s^0$. Thus the physical states are respectively $K_{S}$ and $K_{L}$, $(B_d)_S$ and $(B_d)_L$, and $(B_s)_S$ and $(B_s)_L$. The oscillation between each pair of states can be used to determine their mass difference. The present world average for the $(B_d)_S$--$(B_d)_L$ mass difference is $\Delta m_d = 0.457\pm0.019 ps^{-1}$ (or $(3.01\pm0.13)\times 10^{-4}$ eV). Using $f_{B_s}$ = 12\% (the fraction of $B_s$ produced in b events), the current lower limit on the corresponding $\Delta m_s$ is 6.1 ps$^{-1}$ (or $4.0\times 10^{-3}$ eV).Comment: Invited talk at the XVII International Symposium on Lepton-Photon Interactions, Beijing, China, 1995. 26 pages, latex, 15 figure

A Brief History for the Search and Discovery of the Higgs Particle: A Personal Perspective

In 1964, a new particle was proposed by several groups to answer the question of where the masses of elementary particles come from; this particle is usually referred to as the Higgs particle or the Higgs boson. In July 2012, this Higgs particle was finally found experimentally, a feat accomplished by the ATLAS Collaboration and the CMS Collaboration using the Large Hadron Collider at CERN. It is the purpose of this review to give my personal perspective on a brief history of the experimental search for this particle since the '80s and finally its discovery in 2012. Besides the early searches, those at the LEP collider at CERN, the Tevatron Collider at Fermilab, and the Large Hadron Collider at CERN are described in some detail. This experimental discovery of the Higgs boson is often considered to be one of the most important advances in particle physics in the last half a century, and some of the possible implications are briefly discussed. This review is based on a talk presented by the author at the conference "OCPA8 International Conference on Physics Education and Frontier Physics", the 8th Joint Meeting of Chinese Physicists Worldwide, Nanyang Technological University, Singapore, June 23-27, 2014.Comment: 34 pages, 29 figures, submitted to World Scientific Review Volum

Search for Higgs Bosons Decay H→γγH\to \gamma\gamma Using Vector Boson Fusion

The sensitivity of the ATLAS experiment to low mass SM Higgs produced via Vector Boson Fusion mechanism with $H\to \gamma\gamma$ is invest igated. A cut based event selection has been chosen to optimize the expected signal significance with this decay mode. A signal significance of 2. 2$\sigma$ may be achieved for M_H=130 \gev with 30 fb$^{-1}$ of accumulated luminosity

Higgs production at the large hadron collider: Phenomenological model and theoretical predictions

Using the results from relativistic gauge field theory, a phenomenological model is developed for the production of an isolated Higgs particle H. The specific process is p+p → A+H +B, where the group of particles A (B) mostly goes down one (the other) beam pipe. The theory and the phenomenology apply when the center-of-mass energy √s ≫ M ≫ m, with M and m the masses of the Higgs particle and the proton respectively. Thus, there are two large parameters, namely √s/M and M/m. That M ≫ m plays a central role. This phenomenological model is applied to the Large Hadron Collider (LHC) to predict the differential production cross sections. With high probability, this isolated Higgs particle is produced with a small transverse momentum of the order of 1 GeV/c. Because of this fact and the relatively small number of observed particles in such events, the method of data analysis is different from those developed so far for Higgs detection. These events can be described as due to Pomeron-Pomeron annihilation, and are ‘clean’ in the sense that those from TeV linear colliders are called ‘clean’. The LHC, with its center-of-mass design energy of 14 TeV and its design luminosity of 1034 cm−2s−1, can function exceptionally well as a Pomeron collider.Physic

Prospects for Higgs Searches via VBF at the LHC with the ATLAS Detector

We report on the potential for the discovery of a Standard Model Higgs boson with the vector boson fusion mechanism in the mass range 115 with the ATLAS experiment at the LHC. Feasibility studies at hadron level followed by a fast detector simulation have been performed for H\to W^{(*)}W^{(*)}\to l^+l^-\sla{p_T}, $H\to\gamma\gamma$ and $H\to ZZ\to l^+l^-q\bar{q}$. The results obtained show a large discovery potential in the range 115. Results obtained with multivariate techniques are reported for a number of channels.Comment: 14 pages, 4 figures, contributed to 2003 Les Houches Workshop on Physics at TeV Colliders. Incorporated comments from ATLAS referee

Normalizing Weak Boson Pair Production at the Large Hadron Collider

The production of two weak bosons at the Large Hadron Collider will be one of the most important sources of SM backgrounds for final states with multiple leptons. In this paper we consider several quantities that can help normalize the production of weak boson pairs. Ratios of inclusive cross-sections for production of two weak bosons and Drell-Yan are investigated and the corresponding theoretical errors are evaluated. The possibility of predicting the jet veto survival probability of VV production from Drell-Yan data is also considered. Overall, the theoretical errors on all quantities remain less than 5-20%. The dependence of these quantities on the center of mass energy of the proton-proton collision is also studied.Comment: 11 pages; added references, minor text revisions, version to appear in Phys. Rev.

Transverse momentum distribution of the Z produced at the Large Hadron Collider and related phenomena

From the recent theoretical result on the production of the Higgs boson at the Large Hadron Collider, it follows that other particles will also be produced with small transverse momentum, of the order of 1 GeV/c. The leptonic decay mode of the Z is especially suited for a first observation of this phenomenon. Other related effects, such as paired jets, are also discussed.Engineering and Applied SciencesPhysic