5,327 research outputs found
New Detectors to Explore the Lifetime Frontier
Long-lived particles (LLPs) are a common feature in many beyond the Standard
Model theories, including supersymmetry, and are generically produced in exotic
Higgs decays. Unfortunately, no existing or proposed search strategy will be
able to observe the decay of non-hadronic electrically neutral LLPs with masses
above GeV and lifetimes near the limit set by Big Bang Nucleosynthesis
(BBN), ~m. We propose the MATHUSLA surface
detector concept (MAssive Timing Hodoscope for Ultra Stable neutraL pArticles),
which can be implemented with existing technology and in time for the high
luminosity LHC upgrade to find such ultra-long-lived particles (ULLPs), whether
produced in exotic Higgs decays or more general production modes. We also
advocate for a dedicated LLP detector at a future 100 TeV collider, where a
modestly sized underground design can discover ULLPs with lifetimes at the BBN
limit produced in sub-percent level exotic Higgs decays.Comment: 7 pages, 4 figures. Added more detail to discussion of backgrounds.
Various minor clarifications. Results and conclusions unchange
Fermi Liquids and the Luttinger Integral
The Luttinger Theorem, which relates the electron density to the volume of
the Fermi surface in an itinerant electron system, is taken to be one of the
essential features of a Fermi liquid. The microscopic derivation of this result
depends on the vanishing of a certain integral, the Luttinger integral , which is also the basis of the Friedel sum rule for impurity models,
relating the impurity occupation number to the scattering phase shift of the
conduction electrons. It is known that non-zero values of with
, occur in impurity models in phases with non-analytic low
energy scattering, classified as singular Fermi liquids. Here we show the same
values, , occur in an impurity model in phases with regular
low energy Fermi liquid behavior. Consequently the Luttinger integral can be
taken to characterize these phases, and the quantum critical points separating
them interpreted as topological.Comment: 5 pages 7 figure
On the Surface Area of Scalene Cones and Other Conical Bodies
This paper first appeared in the Novi Commentarii academiae scientiarum Petropolitanae vol. 1, 1750, pp. 3-19 and is reprinted in the Opera Omnia: Series 1, Volume 27, pp. 181–199. Its Eneström number is E133. This translation and the Latin original are available from the Euler Archive
The Surface Area of a Scalene Cone as Solved by Varignon, Leibniz, and Euler
In a 1727 mathematical compendium, Pierre Varignon (1654-1722) published his solution to the problem of finding the surface area of a scalene (oblique) cone, one whose base is circular but whose vertex is off-center. The article after Varignon\u27s in that publication was by Gottfried Leibniz (1646-1716), who proposed improvements and even extended the solution to a base with any curve. When Leonhard Euler (1707-1783) published on the subject [E133] in 1750, he gently pointed out an error in Leibniz\u27s solution, which he corrected, after extending Varignon\u27s solution in the case of circular base. Euler then used Leibniz\u27s approach to solve the general problem. This paper examines all three articles, including English translations
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