More Like this

1. Measurement of Energy Correlators inside Jets and Determination of the Strong Coupling ${\alpha }_S\left(m_Z\right)$

   https://doi.org/10.1103/PhysRevLett.133.071903  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (August 2024, Physical Review Letters)

   Energy correlators that describe energy-weighted distances between two or three particles in a hadronic jet are measured using an event sample of $\sqrt{s}=13\mathrm{TeV}$proton-proton collisions collected by the CMS experiment and corresponding to an integrated luminosity of $36.3{\mathrm{fb}}^{-1}$. The measured distributions are consistent with the trends in the simulation that reveal two key features of the strong interaction: confinement and asymptotic freedom. By comparing the ratio of the measured three- and two-particle energy correlator distributions with theoretical calculations that resum collinear emissions at approximate next-to-next-to-leading-logarithmic accuracy matched to a next-to-leading-order calculation, the strong coupling is determined at the $Z$boson mass: ${\alpha }_S\left(m_Z\right)=0.1229_{-0.0050}^{+0.0040}$, the most precise ${\alpha }_S\left(m_Z\right)$value obtained using jet substructure observables. © 2024 CERN, for the CMS Collaboration2024CERN 

   more » « less
2. One-jettiness DIS event shape at ${\mathrm{N}}^3\mathrm{LL}+\mathcal{O}\left({\alpha }_s^2\right)$

   https://doi.org/10.1103/PhysRevD.110.014045  

   Cao, Haotian; Kang, Zhong-Bo; Liu, Xiaohui; Mantry, Sonny (July 2024, Physical Review D)

   We present results for the ${\tau }_1$and ${\tau }_{1a}$1-jettiness global event shape distributions, for deep inelastic scattering (DIS), at the ${\mathrm{N}}^3\mathrm{LL}+\mathcal{O}\left({\alpha }_s^2\right)$level of accuracy. These event-shape distributions quantify and characterize the pattern of final state radiation in electron-nucleus collisions. They can be used as a probe of nuclear structure functions, as nuclear medium effects in jet production, and for a precision extraction of the QCD strong coupling. The results presented here, along with the corresponding numerical codes, can be used for analyses with HERA data, in Electron-Ion Collider (EIC) simulation studies, and for eventual comparison with real EIC data. Published by the American Physical Society2024 

   more » « less
3. Measurement of the branching fraction and $CP$ -violating asymmetry of the decay $B^0\to {\pi }^0{\pi }^0$ using 387 million $\mathrm{\Upsilon }\left(4S\right)$ decays in Belle II data

   https://doi.org/10.1103/PhysRevD.111.L071102  

   Adachi, I; Aggarwal, L; Ahmed, H; Aihara, H; Alhakami, M; Aloisio, A; Althubiti, N; Anh_Ky, N; Asner, D M; Atmacan, H; et al (April 2025, Physical Review D)

   We measure the branching fraction and $CP$-violating flavor-dependent rate asymmetry of $B^0\to {\pi }^0{\pi }^0$decays reconstructed using the Belle II detector in an electron-positron collision sample containing $387\times {10}^6\mathrm{\Upsilon }\left(4S\right)$mesons. Using an optimized event selection, we find $125\pm 20$signal decays in a fit to background-discriminating and flavor-sensitive distributions. The resulting branching fraction is $(1.25\pm 0.23)\times {10}^{-6}$and the $CP$-violating asymmetry is $0.03\pm 0.30$. Published by the American Physical Society2025 

   more » « less
4. A QCD $R$ -axion

   https://doi.org/10.1103/PhysRevD.111.015048  

   Unwin, James; Yildirim, Tom (January 2025, Physical Review D)

   $R$-parity can be extended to a continuous global $\mathrm{U}(1{)}_R$symmetry. We investigate whether an anomalous $\mathrm{U}(1{)}_R$can be identified as the Peccei-Quinn symmetry suitable for solving the strong $CP$problem within supersymmetric extensions of the Standard Model. In this case, $\mathrm{U}(1{)}_R$is broken at some intermediate scale and the quantum chromodynamics axion is the $R$-axion. Moreover, the $R$-symmetry can potentially be gauged via the Green-Schwarz mechanism within completions to supergravity, in order to evade the axion quality problem. Obstacles to realizing this scenario are highlighted and phenomenologically viable approaches are identified. Published by the American Physical Society2025 

   more » « less
5. Pseudo-easy-axis anisotropy in antiferromagnetic $S=1$ diamond-lattice systems

   https://doi.org/10.1103/PhysRevB.110.174438  

   Vaidya, S; Hernández-Melián, A; Tidey, J P; Curley, S_P M; Sharma, S; Manuel, P; Wang, C; Hannaford, G L; Blundell, S J; Manson, Z E; et al (November 2024, Physical Review B)

   We investigate the magnetic properties of $S=1$antiferromagnetic diamond-lattice, $\mathrm{Ni}{X}_2{\left(\mathrm{pyrimidine}\right)}_2$ $(X=\mathrm{Cl}, \mathrm{Br})$, hosting a single-ion anisotropy (SIA) orientation which alternates between neighboring sites. Through neutron diffraction measurements of the $X=\mathrm{Cl}$compound, the ordered state spins are found to align collinearly along a pseudo-easy axis, a unique direction created by the intersection of two easy planes. Similarities in the magnetization, exhibiting spin-flop transitions, and the magnetic susceptibility in the two compounds imply that the same magnetic structure and a pseudo-easy axis is also present for $X=\mathrm{Br}$. We estimate the Hamiltonian parameters by combining analytical calculations and Monte Carlo (MC) simulations of the spin-flop and saturation field. The MC simulations also reveal that the spin-flop transition occurs when the applied field is parallel to the pseudo-easy axis. Contrary to conventional easy-axis systems, there exist field directions perpendicular to the pseudo-easy axis for which the magnetic saturation is approached asymptotically and no symmetry-breaking phase transition is observed at finite fields. Published by the American Physical Society2024 

   more » « less