Cyclicity of All Anti-NMHV and N2^2MHV Tree Amplitudes in N=4 SYM

This article proves the cyclicity of anti-NMHV and N$^2$MHV tree amplitudes in planar N=4 SYM up to any number of external particles as an interesting application of positive Grassmannian geometry. In this proof the two-fold simplex-like structures of tree amplitudes introduced in 1609.08627 play a key role, as the cyclicity of amplitudes will induce similar simplex-like structures for the boundary generators of homological identities. For this purpose, we only need a part of all distinct boundary generators, and the relevant identities only involve BCFW-like cells. The manifest cyclic invariance in this geometric representation reflects one of the invariant characteristics of amplitudes, though they are obtained by the scheme-dependent BCFW recursion relation.Comment: 13 pages, 1 appendi

The RPC-based proposal for the ATLAS forward muon trigger upgrade in view of super-LHC

The innermost station of the present ATLAS forward muon detector needs to be upgraded for the super-LHC. We present a proposal to replace it with a sandwiched detector composed of several layers of small-radius Monitored Drift Tube chambers (sMDT) for precision tracking measurement and two stations of multi-gap Resistive Plate Chambers (mRPC) for triggering purpose. We describe the layout of the upgraded detector and the trigger strategy. Several modifications to the RPCs used in the ATLAS barrel region are needed to satisfy the super-LHC requirements. Various studies with the proposed mRPC timing resolution, spatial resolution and rate capability have been performed.Comment: 6 pages, 8 figures, proceeding for XI workshop on Resistive Plate Chambers and Related Detectors - RCP201

4-particle Amplituhedron at 3-loop and its Mondrian Diagrammatic Implication

This article provides a direct calculation of the 4-particle amplituhedron at 3-loop order, by introducing a set of practical tricks. After delicately rearranging each piece of this calculation, we find a suggestive connection between positivity conditions and Mondrian diagrams, which will be quantitatively defined. Such a pattern can be generalized for all Mondrian diagrams among all those contribute to the 4-particle integrand of planar N=4 SYM to all loop orders, as a subsequent work 1712.09994 will show.Comment: 32 pages, 3 figures, 1 appendix. Figures improved for v

Electroweak results from the ATLAS and CMS experiments

I summarize an extensive ATLAS and CMS electroweak physics program that involves a variety of single boson, diboson, triboson, and vector boson scattering measurements. The relevance of these studies to our understanding of the electroweak sector and electroweak symmetry breaking is emphasized. I describe the recent results and prospects for future measurements.Comment: 13 pages, 5 figures, Proceeding for the DPF meeting at the University of Michiga

Land Use Changes: Economic, Social, and Environmental Impacts

Land Economics/Use, Q24, Q28,