Market Shares, Consumer Ignorance and the Reciprocal Termination Charges

The aim of this paper is to study different regulatory effects on termination charges and social welfare. We employ a framework with a fixed network and two mobile networks competing in a market to study the following regulatory regimes: collusive and social welfaremaximising reciprocity, uniform termination charge, asymmetric regulation, and direct calling price. We incorporate the idea of partial consumer ignorance when calling to a mobile user and allow the network operator to discriminate between on-net and off-net calls by setting differential calling prices. Compared to the uniform termination charge and asymmetric regulation, it is shown in this paper that the regulator can improve social welfare, without too much intervention, by imposing reciprocity on termination charges. We also find that with stronger consumer ignorance the regulator is more capable of improving social welfare. Further we show that, depending upon the extent of consumer ignorance, direct regulation of calling prices may be a welfare-improving alternative over regulation of termination charges.Telecommunications; Consumer ignorance; Termination Charges, Regulation

Searches for New Physics at the Tevatron in Photon and Jet Final States

We present the results of searches for non-standard model phenomena in photon and jet final states. These searches use data from integrated luminosities of 0.7--2.7/fb of p-pbar collisions at sqrt(s)=1.96 TeV, collected with the CDF and D0 detectors at the Fermilab Tevatron. No significant excess in data has been observed. We report limits on the parameters of several models, including: large extra dimension, compositeness, leptoquarks, and supersymmetry.Comment: Proceedings for the Moriond 2009 EW session 7 pages, 6 figure

Review of Recent Tevatron Jet, W/Z+Jet and Heavy-flavor Production Results

This document reviews several recent measurements at the Fermilab Tevatron, including the cross sections of inclusive jet, dijet production, the cross sections of electroweak boson (W or Z) production in association with inclusive or heavy-flavor (b or c) jets, and b-jet shapes. In addition, searches for new physics using the dijet angular distributions are discussed. These analyses are based on integrated luminosities of 0.3--2.5/fb of p-pbar collisions at \sqrt{s}=1.96 TeV, collected with the CDF and D0 detectors. The results directly test the leading order and next-to leading order calculations of perturbative quantum chromodynamics and provide constraints on the parton distribution functions, gluon-splitting contribution, and physics beyond the standard model.Comment: 10 pages, 7 figures, Proceedings for Photon 200

Describing a Quantum Channel by State Tomography of a Single Probe State

A general law is presented for (composite) quantum systems which directly describes the time evolution of quantum states (with one or both components) through an arbitrary noisy quantum channel. It is shown that the time evolution of all quantum states through a quantum channel can be completely captured by the evolution of a single 'probe state'. Thus in order to grasp the information of the final output states subject to a quantum channel, especially an unknown one, it only requires quantum state tomography of a single probe state, which dramatically simplifies the practical operations in experiment.Comment: 3 pages, To be publised in EP

Two-dimensional Spin-Orbit Dirac Point in Monolayer HfGeTe

Dirac points in two-dimensional (2D) materials have been a fascinating subject of research, with graphene as the most prominent example. However, the Dirac points in existing 2D materials, including graphene, are vulnerable against spin-orbit coupling (SOC). Here, based on first-principles calculations and theoretical analysis, we propose a new family of stable 2D materials, the HfGeTe-family monolayers, which represent the first example to host so-called spin-orbit Dirac points (SDPs) close to the Fermi level. These Dirac points are special in that they are formed only under significant SOC, hence they are intrinsically robust against SOC. We show that the existence of a pair of SDPs are dictated by the nonsymmorphic space group symmetry of the system, which are very robust under various types of lattice strains. The energy, the dispersion, and the valley occupation around the Dirac points can be effectively tuned by strain. We construct a low-energy effective model to characterize the Dirac fermions around the SDPs. Furthermore, we find that the material is simultaneously a 2D $\mathbb{Z}_2$ topological metal, which possesses nontrivial $\mathbb{Z}_2$ invariant in the bulk and spin-helical edge states on the boundary. From the calculated exfoliation energies and mechanical properties, we show that these materials can be readily obtained in experiment from the existing bulk materials. Our result reveals HfGeTe-family monolayers as a promising platform for exploring spin-orbit Dirac fermions and novel topological phases in two-dimensions.Comment: 9 pages, 6 figure

Search for Higgs at CDF

We present the results on the searches for the SM and the non-SM Higgs boson production in ppbar collisions at sqrt(s)=1.96 TeV with the CDF detector at the Fermilab Tevatron. Using data corresponding to 300--700pb-1, we search for the Higgs boson in various production and decay channels. No signal is observed, therefore, we set upper limits on the production cross-section times branching fraction as a function of the Higgs boson mass.Comment: to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

Search for Anomalous Production of Photon, b-jet, and Missing Transverse Energy at CDF

We report the results of two signature-based searches for new physics using 1.9- 2.0 fb-1 of data collected at the CDF experiment. Both analyses look in events containing a photon, a b-tagged jet, and missing transverse energy. The first search requires an additional jet. The second search requires an extra electron or muon. No significant excess of events over the Standard Model prediction is observed. We also describe the "CES/CPR" method which is used to estimate the amount of mis-identified photons.Comment: Poster at the 34th International Conference on High Energy Physics, ICHEP08, Philadelphia, USA, July 2008. 3 pages, LaTeX, 2 eps figure