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1. General mass variable flavor number scheme for $Z$ boson production in association with a heavy quark at hadron colliders

   https://doi.org/10.1103/PhysRevD.110.114030  

   Guzzi, Marco; Nadolsky, Pavel; Reina, Laura; Wackeroth, Doreen; Xie, Keping (December 2024, Physical Review D)

   We present a methodology to streamline implementation of massive-quark radiative contributions in calculations with a variable number of active partons in proton-proton collisions. The methodology introduces and heavy-quark parton distribution functions (PDFs) to implement calculations in the Aivazis–Collins–Olness–Tung (ACOT) factorization scheme and its simplified realization in various processes up to the next-to-the-next-to-leading order in the QCD coupling strength. Interpolation tables for bottom-quark subtraction and residual distributions for CT18 NLO and NNLO PDF ensembles are provided in the common LHAPDF6 format. A numerical calculation of $Z$-boson production with at least one $b$jet at the Large Hadron Collider beyond the lowest order in QCD is considered for illustration purposes. Published by the American Physical Society2024 

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2. Circularly polarized photon emission from magnetized chiral plasmas

   https://doi.org/10.1103/PhysRevD.110.116005  

   Wang, Xinyang; Shovkovy, Igor A (December 2024, Physical Review D)

   We investigate the emission of circularly polarized photons from a magnetized quark-gluon plasma with nonzero quark-number and chiral charge chemical potentials. These chemical potentials qualitatively influence the differential emission rates of circularly polarized photons. A nonzero net electric charge density, induced by quark-number chemical potentials, enhances the overall emission of one circular polarization over the other, while a nonzero chiral charge density introduces a spatial asymmetry in the emission with respect to reflection in the transverse plane. The signs of the electrical and chiral charge densities determine which circular polarization dominates overall and whether the emission preferentially aligns with or opposes the magnetic field. Based on these findings, we propose that polarized photon emission is a promising observable for characterizing the quark-gluon plasma produced in heavy-ion collisions. Published by the American Physical Society2024 

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3. First Measurement of Deeply Virtual Compton Scattering on the Neutron with Detection of the Active Neutron

   https://doi.org/10.1103/PhysRevLett.133.211903  

   Hobart, A; Niccolai, S; Čuić, M; Kumerički, K; Achenbach, P; Alvarado, J S; Armstrong, W R; Atac, H; Avakian, H; Baashen, L; et al (November 2024, Physical Review Letters)

   Measuring deeply virtual Compton scattering (DVCS) on the neutron is one of the necessary steps to understand the structure of the nucleon in terms of generalized parton distributions (GPDs). Neutron targets play a complementary role to transversely polarized proton targets in the determination of the GPD $E$. This poorly known and poorly constrained GPD is essential to obtain the contribution of the quarks’ angular momentum to the spin of the nucleon. DVCS on the neutron was measured for the first time selecting the exclusive final state by detecting the neutron, using the Jefferson Lab longitudinally polarized electron beam, with energies up to 10.6 GeV, and the CLAS12 detector. The extracted beam-spin asymmetries, combined with DVCS observables measured on the proton, allow a clean quark-flavor separation of the imaginary parts of the Compton form factors $\mathcal{H}$and $\mathcal{E}$. Published by the American Physical Society2024 

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4. Quark counting, Drell-Yan West, and the pion wave function

   https://doi.org/10.1103/PhysRevC.110.L042201  

   Alberg, Mary; Miller, Gerald A (October 2024, Physical Review C)

   The relation between the pion's quark distribution function, $q\left(x\right)$, its light-front wave function, and the elastic charge form factor, $F\left({\mathrm{\Delta }}^2\right)$, is explored. The square of the leading-twist pion wave function at a special probe scale, ${\zeta }_H$, is determined using models and Poincaré covariance from realistic results for $q\left(x\right)$. This wave function is then used to compute form factors with the result that the Drell-Yan-West and quark counting relationships are not satisfied. A new relationship between $q\left(x\right)$and $F\left({\mathrm{\Delta }}^2\right)$is proposed. Published by the American Physical Society2024 

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5. Combination of Measurements of the Top Quark Mass from Data Collected by the ATLAS and CMS Experiments at $\sqrt{s}=7$ and 8 TeV

   https://doi.org/10.1103/PhysRevLett.132.261902  

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

   A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The datasets used correspond to an integrated luminosity of up to 5 and $20{\mathrm{fb}}^{-1}$of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak $t$channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is $m_t=172.52\pm 0.14\left(\mathrm{stat}\right)\pm 0.30\left(\mathrm{syst}\right)\mathrm{GeV}$, with a total uncertainty of 0.33 GeV. © 2024 CERN, for the CMS and ATLASs Collaboration2024CERN 

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