More Like this

1. The effect of metric behavior at spatial infinity on pointwise wave decay in the asymptotically flat stationary setting

   https://doi.org/10.1353/ajm.2024.a917539  

   Morgan, Katrina (February 2024, American Journal of Mathematics)

   abstract: The current work considers solutions to the wave equation on asymptotically flat, stationary, Lorentzian spacetimes in $(1+3)$ dimensions. We investigate the relationship between the rate at which the geometry tends to flat and the pointwise decay rate of solutions. The case where the spacetime tends toward flat at a rate of $$|x|^{-1}$$ was studied by Tataru (2013), where a $$t^{-3}$$ pointwise decay rate was established. Here we extend the result to geometries tending toward flat at a rate of $$|x|^{-\kappa}$$ and establish a pointwise decay rate of $$t^{-\kappa-2}$$ for $$\kappa\in\Bbb{N}$$ with $$\kappa\ge 2$$. We assume a weak local energy decay estimate holds, which restricts the geodesic trapping allowed on the underlying geometry. We use the resolvent to connect the time Fourier Transform of a solution to the Cauchy data. Ultimately the rate of pointwise wave decay depends on the low frequency behavior of the resolvent, which is sensitive to the rate at which the background geometry tends to flat. 

   more » « less
2. Direct constraint on the Higgs–charm coupling from a search for Higgs boson decays into charm quarks with the ATLAS detector

   https://doi.org/10.1140/epjc/s10052-022-10588-3  

   Aad, G.; Abbott, B.; Abbott, D. C.; Abud, A. Abed; Abeling, K.; Abhayasinghe, D. K.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; et al (August 2022, The European Physical Journal C)

   Abstract A search for the Higgs boson decaying into a pair of charm quarks is presented. The analysis uses proton–proton collisions to target the production of a Higgs boson in association with a leptonically decaying W or Z boson. The dataset delivered by the LHC at a centre-of-mass energy of "Equation missing" and recorded by the ATLAS detector corresponds to an integrated luminosity of 139  $$\text{ fb}^{-1}$$ fb - 1 . Flavour-tagging algorithms are used to identify jets originating from the hadronisation of charm quarks. The analysis method is validated with the simultaneous measurement of WW ,  WZ and ZZ production, with observed (expected) significances of 2.6 (2.2) standard deviations above the background-only prediction for the $$(W/Z)Z(\rightarrow c{\bar{c}})$$ ( W / Z ) Z ( → c c ¯ ) process and 3.8 (4.6) standard deviations for the $$(W/Z)W(\rightarrow cq)$$ ( W / Z ) W ( → c q ) process. The $$(W/Z)H(\rightarrow c {\bar{c}})$$ ( W / Z ) H ( → c c ¯ ) search yields an observed (expected) upper limit of 26 (31) times the predicted Standard Model cross-section times branching fraction for a Higgs boson with a mass of "Equation missing" , corresponding to an observed (expected) constraint on the charm Yukawa coupling modifier $$|\kappa _c| < 8.5~(12.4)$$ | κ c | < 8.5 ( 12.4 ) , at the 95% confidence level. A combination with the ATLAS $$(W/Z)H, H\rightarrow b{\bar{b}}$$ ( W / Z ) H , H → b b ¯ analysis is performed, allowing the ratio $$\kappa _c / \kappa _b$$ κ c / κ b to be constrained to less than 4.5 at the 95% confidence level, smaller than the ratio of the b- and c-quark masses, and therefore determines the Higgs-charm coupling to be weaker than the Higgs-bottom coupling at the 95% confidence level. 

   more » « less
3. Unavoidable structures in infinite tournaments

   https://doi.org/10.1090/proc/16940  

   Benford, Alistair; DeBiasio, Louis; Larson, Paul (October 2024, Proceedings of the American Mathematical Society)

   We prove a strong dichotomy result for countably-infinite oriented graphs; that is, we prove that for all countably-infinite oriented graphs $G$, either (i) there is a countably-infinite tournament $K$such that $G⊈K$, or (ii) every countably-infinite tournament contains aspanningcopy of $G$. Furthermore, we are able to give a concise characterization of such oriented graphs. Our characterization becomes even simpler in the case of transitive acyclic oriented graphs (i.e. strict partial orders). For uncountable oriented graphs, we are able to extend the dichotomy result mentioned above to all regular cardinals $\mathrm{\kappa <\#comment/>}$; however, we are only able to provide a concise characterization in the case when $\mathrm{\kappa <\#comment/>}={\mathrm{\aleph <\#comment/>}}_1$. 

   more » « less
4. Application of a Controlled Assembly Vocabulary: Modeling a Home Appliance Transfer Line

   https://doi.org/10.1007/978-3-030-29996-5_51  

   Wentzky, E.; Spence, C.; Patel, A.; Zero, N.; Jeyes, A.; Fiore, A.; Summers, J.; Kurz, M.; Taaffe, K. (August 2019, Advances in Production Management Systems. Towards Smart Production Management Systems. APMS 2019.)

   A controlled vocabulary list that was originally developed for the automotive assembly environment was modified for home appliance assembly in this study. After surveying over 700 assembly tasks with the original vocabulary, additions were made to the vocabulary list as necessary. The vocabulary allowed for the transformation of work instructions in approximately 90% of cases, with the most discrepancies occurring during the inspection phase of the transfer line. The modified vocabulary list was then tested for coder reliability to ensure broad usability and was found to have Cohen’s kappa values of 0.671 < κ < 0.848 between coders and kappa values of 0.731 < κ < 0.875 within coders over time. Using this analysis, it was demonstrated that this original automotive vocabulary could be applied to the non-automotive context with a high degree of reliability and consistency. 

   more » « less
5. Fast and fair randomized wait-free locks

   https://doi.org/10.1007/s00446-024-00474-4  

   Ben-David, Naama; Blelloch, Guy E (March 2025, Distributed Computing)

   Abstract We present a randomized approach for wait-free locks with strong bounds on time and fairness in a context in which any process can be arbitrarily delayed. Our approach supports a tryLock operation that is given a set of locks, and code to run when all the locks are acquired. A tryLock operation may fail if there is contention on the locks, in which case the code is not run. Given an upper bound$$\kappa $$ $\kappa$known to the algorithm on the point contention of any lock, and an upper boundLon the number of locks in a tryLock’s set, a tryLock will succeed in acquiring its locks and running the code with probability at least$$1/(\kappa L)$$ $1/\left(\kappa L\right)$. It is thus fair. Furthermore, if the maximum step complexity for the code in any lock isT, the operation will take$$O(\kappa ^2 L^2 T)$$ $O\left({\kappa }^2{L}^{2}T\right)$steps, regardless of whether it succeeds or fails. The operations are independent, thus if the tryLock is repeatedly retried on failure, it will succeed in$$O(\kappa ^3 L^3 T)$$ $O\left({\kappa }^3{L}^{3}T\right)$expected steps. If the algorithm does not know the bounds$$\kappa $$ $\kappa$andL, we present a variant that can guarantee a probability of at least$$1/\kappa L\log (\kappa L T)$$ $1/\kappa Llog\left(\kappa LT\right)$of success. We assume an oblivious adversarial scheduler, which does not make decisions based on the operations, but can predetermine any schedule for the processes, which is unknown to our algorithm. Furthermore, to account for applications that change their future requests based on the results of previous tryLock operations, we strengthen the adversary by allowing decisions of the start times and lock sets of tryLock operations to be made adaptively, given the history of the execution so far. 

   more » « less