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1. Calderón–Zygmund theory for strongly coupled linear system of nonlocal equations with Hölder-regular coefficient

   https://doi.org/10.1515/acv-2024-0005  

   Mengesha, Tadele; Schikorra, Armin; Seesanea, Adisak; Yeepo, Sasikarn (November 2024, Advances in Calculus of Variations)

   Abstract We extend the Calderón–Zygmund theory for nonlocal equations tostrongly coupled system of linear nonlocal equations ${\mathcal{ℒ}}_A^{s}u=f${\mathcal{L}^{s}_{A}u=f}, where the operator ${\mathcal{ℒ}}_A^s${\mathcal{L}^{s}_{A}}is formally given by ${\mathcal{ℒ}}_A^{s}u={\int }_{{ℝ}^n}\frac{A(x,y)}{{\left|x-y\right|}^{n+2s}}\frac{\left(x-y\right)\otimes \left(x-y\right)}{{\left|x-y\right|}^2}\left(u\left(x\right)-u\left(y\right)\right)𝑑y.$\mathcal{L}^{s}_{A}u=\int_{\mathbb{R}^{n}}\frac{A(x,y)}{|x-y|^{n+2s}}\frac{(x-%y)\otimes(x-y)}{|x-y|^{2}}(u(x)-u(y))\,dy. For $0<s<1${0<1}and $A:{ℝ}^n\times {ℝ}^n\to ℝ${A:\mathbb{R}^{n}\times\mathbb{R}^{n}\to\mathbb{R}}taken to be symmetric and serving asa variable coefficient for the operator, the system under consideration is the fractional version of the classical Navier–Lamé linearized elasticity system. The study of the coupled system of nonlocal equations is motivated by its appearance in nonlocal mechanics, primarily in peridynamics. Our regularity result states that if $A(\cdot ,y)${A(\,\cdot\,,y)}is uniformly Holder continuous and ${inf}_{x\in {ℝ}^n}A(x,x)>0${\inf_{x\in\mathbb{R}^{n}}A(x,x)>0}, then for $f\in L_{\mathrm{loc}}^p${f\in L^{p}_{\rm loc}}, for $p\ge 2${p\geq 2}, the solution vector $u\in H_{\mathrm{loc}}^{2s-\delta ,p}${u\in H^{2s-\delta,p}_{\rm loc}}for some $\delta \in (0,s)${\delta\in(0,s)}. 

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2. Using collision-induced dissociation to constrain sensitivity of ammonia chemical ionization mass spectrometry (NH₄⁺ CIMS) to oxygenated volatile organic compounds

   https://doi.org/10.5194/amt-12-1861-2019  

   Zaytsev, Alexander; Breitenlechner, Martin; Koss, Abigail R.; Lim, Christopher Y.; Rowe, James C.; Kroll, Jesse H.; Keutsch, Frank N. (January 2019, Atmospheric Measurement Techniques)

   Abstract. Chemical ionization massspectrometry (CIMS) instruments routinely detect hundreds of oxidized organic compoundsin the atmosphere. A major limitation of these instruments is the uncertaintyin their sensitivity to many of the detected ions. We describe thedevelopment of a new high-resolution time-of-flight chemical ionization massspectrometer that operates in one of two ionization modes: using eitherammonium ion ligand-switching reactions such as for ${\mathrm{NH}}_4^{+}$ CIMS orproton transfer reactions such as for proton-transfer-reaction massspectrometer (PTR-MS). Switching between the modes can be done within 2&thinsp;min.The ${\mathrm{NH}}_4^{+}$ CIMS mode of the new instrument has sensitivities of upto 67&thinsp;000&thinsp;dcps&thinsp;ppbv⁻¹ (duty-cycle-corrected ion counts per second perpart per billion by volume) and detection limits between 1 and 60&thinsp;pptv at2σ for a 1&thinsp;s integration time for numerous oxygenated volatileorganic compounds. We present a mass spectrometric voltage scanning procedurebased on collision-induced dissociation that allows us to determine thestability of ammonium-organic ions detected by the ${\mathrm{NH}}_4^{+}$ CIMS instrument.Using this procedure, we can effectively constrain the sensitivity of theammonia chemical ionization mass spectrometer to a wide range of detectedoxidized volatile organic compounds for which no calibration standards exist.We demonstrate the application of this procedure by quantifying thecomposition of secondary organic aerosols in a series of laboratoryexperiments. 

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3. Modifications of ion beam sputtered tantala thin films by secondary argon and oxygen bombardment

   https://doi.org/10.1364/AO.59.00A150  

   Yang, Le; Randel, Emmett; Vajente, Gabriele; Ananyeva, Alena; Gustafson, Eric; Markosyan, Ashot; Bassiri, Riccardo; Fejer, Martin; Menoni, Carmen (January 2020, Applied Optics)

   Amorphous tantala ( ${\mathrm{T}\mathrm{a}}_2{\mathrm{O}}_5$) thin films were deposited by reactive ion beam sputtering with simultaneous low energy assist ${\mathrm{A}\mathrm{r}}^{+}$or ${\mathrm{A}\mathrm{r}}^{+}/{\mathrm{O}}_2^{+}$bombardment. Under the conditions of the experiment, the as-deposited thin films are amorphous and stoichiometric. The refractive index and optical band gap of thin films remain unchanged by ion bombardment. Around 20% improvement in room temperature mechanical loss and 60% decrease in absorption loss are found in samples bombarded with 100-eV ${\mathrm{A}\mathrm{r}}^{+}$. A detrimental influence from low energy ${\mathrm{O}}_2^{+}$bombardment on absorption loss and mechanical loss is observed. Low energy ${\mathrm{A}\mathrm{r}}^{+}$bombardment removes excess oxygen point defects, while ${\mathrm{O}}_2^{+}$bombardment introduces defects into the tantala films. 

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4. Search for CP violation in $${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ decays in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$

   https://doi.org/10.1140/epjc/s10052-024-13244-0  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (December 2024, The European Physical Journal C)

   Abstract A search is reported for charge-parity$$CP$$ $\mathrm{CP}$violation in$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ ${\text{D}}^0\to {\text{K}}_{\text{S}}^0{\text{K}}_{\text{S}}^0$decays, using data collected in proton–proton collisions at$$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$ $\sqrt{s}=13\text{Te}\text{V}$recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6$$\,\text {fb}^{-1}$$ ${\text{fb}}^{-1}$, which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays$${{{\textrm{D}}}^{{*+}}} \rightarrow {{{\textrm{D}}}^{{0}}} {{{\mathrm{\uppi }}}^{{+}}} $$ $\text{D}_{}^{\ast +}\to {\text{D}}^0{\pi }^{+}$and$${{{\textrm{D}}}^{{*-}}} \rightarrow {\overline{{\textrm{D}}}^{{0}}} {{{\mathrm{\uppi }}}^{{-}}} $$ $\text{D}_{}^{\ast -}\to {\overline{\text{D}}}^0{\pi }^{-}$. The$$CP$$ $\mathrm{CP}$asymmetry in$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ ${\text{D}}^0\to {\text{K}}_{\text{S}}^0{\text{K}}_{\text{S}}^0$is measured to be$$A_{CP} ({{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} ) = (6.2 \pm 3.0 \pm 0.2 \pm 0.8)\%$$ $A_{\mathrm{CP}}\left({\text{K}}_{\text{S}}^0{\text{K}}_{\text{S}}^0\right)=(6.2\pm 3.0\pm 0.2\pm 0.8)\%$, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the$$CP$$ $\mathrm{CP}$asymmetry in the$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{{\mathrm{\uppi }}}^{{+}}} {{{\mathrm{\uppi }}}^{{-}}} $$ ${\text{D}}^0\to {\text{K}}_{\text{S}}^0{\pi }^{+}{\pi }^{-}$decay. This is the first$$CP$$ $\mathrm{CP}$asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state. 

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5. Observation of the $${{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} $$ decay

   https://doi.org/10.1140/epjc/s10052-024-13114-9  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Valle, A_Escalante Del; Hussain, P S; et al (October 2024, The European Physical Journal C)

   Abstract Using proton–proton collision data corresponding to an integrated luminosity of$$140\hbox { fb}^{-1}$$ $140{\text{fb}}^{-1}$collected by the CMS experiment at$$\sqrt{s}= 13\,\text {Te}\hspace{-.08em}\text {V} $$ $\sqrt{s}=13\text{Te}\text{V}$, the$${{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} $$ ${\Lambda }_{\text{b}}^0\to \text{J}/\psi {\Xi }^{-}{\text{K}}^{+}$decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the$${{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{{\uppsi }} ({2\textrm{S}})} {{\Lambda }} $$ ${\Lambda }_{\text{b}}^0\to \psi \left(2\text{S}\right)\Lambda$decay, is measured to be$$\mathcal {B}({{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} )/\mathcal {B}({{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{{\uppsi }} ({2\textrm{S}})} {{\Lambda }} ) = [3.38\pm 1.02\pm 0.61\pm 0.03]\%$$ $B({\Lambda }_{\text{b}}^0\to \text{J}/\psi {\Xi }^{-}{\text{K}}^{+})/B({\Lambda }_{\text{b}}^0\to \psi \left(2\text{S}\right)\Lambda )=[3.38\pm 1.02\pm 0.61\pm 0.03]\%$, where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in$$\mathcal {B}({{{\uppsi }} ({2\textrm{S}})} \rightarrow {{\text {J}/\uppsi }} {{{\uppi }} ^{{+}}} {{{\uppi }} ^{{-}}} )$$ $B(\psi \left(2\text{S}\right)\to \text{J}/\psi {\pi }^{+}{\pi }^{-})$and$$\mathcal {B}({{{\Xi }} ^{{-}}} \rightarrow {{\Lambda }} {{{\uppi }} ^{{-}}} )$$ $B({\Xi }^{-}\to \Lambda {\pi }^{-})$. 

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