More Like this

1. Workshop summary: Kaons@CERN 2023

   https://doi.org/10.1140/epjc/s10052-024-12565-4  

   Anzivino, G; Cuendis, Sergio Arguedas; Bernard, V; Bijnens, J; Bloch-Devaux, B; Bordone, M; Brizioli, F; Brod, J; Camalich, J M; Ceccucci, A; et al (April 2024, The European Physical Journal C)

   Abstract Kaon physics is at a turning point – while the rare-kaon experiments NA62 and KOTO are in full swing, the end of their lifetime is approaching and the future experimental landscape needs to be defined. With HIKE, KOTO-II and LHCb-Phase-II on the table and under scrutiny, it is a very good moment in time to take stock and contemplate about the opportunities these experiments and theoretical developments provide for particle physics in the coming decade and beyond. This paper provides a compact summary of talks and discussions from the Kaons@CERN 2023 workshop, held in September 2023 at CERN. 

   more » « less
2. Search for a Hidden Sector Scalar from Kaon Decay in the Dimuon Final State at ICARUS

   https://doi.org/10.1103/PhysRevLett.134.151801  

   Abd_Alrahman, F; Abratenko, P; Abrego-Martinez, N; Aduszkiewicz, A; Akbar, F; Aliaga_Soplin, L; Alvarez_Garrote, R; Artero_Pons, M; Asaadi, J; Badgett, W F; et al (April 2025, Physical Review Letters)

   We present a search for long-lived particles (LLPs), produced in kaon decays, that decay to two muons inside the ICARUS neutrino detector. This channel would be a signal of hidden sector models that can address outstanding issues in particle physics such as the strong CP problem and the microphysical origin of dark matter. The search is performed with data collected in the Neutrinos at the Main Injector (NuMI) beam at Fermilab corresponding to $2.41\times {10}^{20}$protons-on-target. No new physics signal is observed, and we set world leading limits on heavy QCD axions, as well as for the Higgs portal scalar among dedicated searches. Limits are also presented in a model-independent way applicable to any new physics model predicting the process $K\to \pi +S(\to \mu \mu )$, for a LLP $S$. This result is the first search for new physics performed with the ICARUS detector at Fermilab. It paves the way for the future program of LLP searches at ICARUS. Published by the American Physical Society2025 

   more » « less
3. An investigation of the very rare $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ decay

   https://doi.org/10.1007/JHEP11(2020)042  

   Cortina Gil, E.; Kleimenova, A.; Minucci, E.; Padolski, S.; Petrov, P.; Shaikhiev, A.; Volpe, R.; Numao, T.; Velghe, B.; Bryman, D.; et al (November 2020, Journal of High Energy Physics)

   null (Ed.)

   A bstract The NA62 experiment reports an investigation of the $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ K + → π + ν ν ¯ mode from a sample of K + decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of (0 . 389 ± 0 . 024) × 10 − 10 , corresponding to 2.2 events assuming the Standard Model branching ratio of (8 . 4 ± 1 . 0) × 10 − 11 . Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of 1 . 78 × 10 − 10 for the $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ K + → π + ν ν ¯ branching ratio at 90% CL. This, together with the corresponding 68% CL measurement of ( $$ {0.48}_{-0.48}^{+0.72} $$ 0.48 − 0.48 + 0.72 ) × 10 − 10 , are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements. 

   more » « less
4. Computing optimal factories in metabolic networks with negative regulation

   https://doi.org/10.1093/bioinformatics/btac231  

   Krieger, Spencer; Kececioglu, John (June 2022, Bioinformatics)

   Abstract MotivationA factory in a metabolic network specifies how to produce target molecules from source compounds through biochemical reactions, properly accounting for reaction stoichiometry to conserve or not deplete intermediate metabolites. While finding factories is a fundamental problem in systems biology, available methods do not consider the number of reactions used, nor address negative regulation. MethodsWe introduce the new problem of finding optimal factories that use the fewest reactions, for the first time incorporating both first- and second-order negative regulation. We model this problem with directed hypergraphs, prove it is NP-complete, solve it via mixed-integer linear programming, and accommodate second-order negative regulation by an iterative approach that generates next-best factories. ResultsThis optimization-based approach is remarkably fast in practice, typically finding optimal factories in a few seconds, even for metabolic networks involving tens of thousands of reactions and metabolites, as demonstrated through comprehensive experiments across all instances from standard reaction databases. Availability and implementationSource code for an implementation of our new method for optimal factories with negative regulation in a new tool called Odinn, together with all datasets, is available free for non-commercial use at http://odinn.cs.arizona.edu. 

   more » « less
5. Search for a feebly interacting particle X in the decay K+ → π+X

   https://doi.org/10.1007/JHEP03(2021)058  

   Cortina Gil, E.; Kleimenova, A.; Minucci, E.; Padolski, S.; Petrov, P.; Shaikhiev, A.; Volpe, R.; Numao, T.; Velghe, B.; Bryman, D.; et al (March 2021, Journal of High Energy Physics)

   null (Ed.)

   A bstract A search for the K + → π + X decay, where X is a long-lived feebly interacting particle, is performed through an interpretation of the K + → $$ {\pi}^{+}\nu \overline{\nu} $$ π + ν ν ¯ analysis of data collected in 2017 by the NA62 experiment at CERN. Two ranges of X masses, 0–110 MeV /c 2 and 154–260 MeV /c 2 , and lifetimes above 100 ps are considered. The limits set on the branching ratio, BR( K + → π + X ), are competitive with previously reported searches in the first mass range, and improve on current limits in the second mass range by more than an order of magnitude. 

   more » « less