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1. Reduction of the electroweak correlation in the PDF updating by using the forward–backward asymmetry of Drell–Yan process

   https://doi.org/10.1140/epjc/s10052-022-10280-6  

   Yang, Siqi ; Fu, Yao ; Liu, Minghui ; Zhang, Renyou ; Hou, Tie-Jiun ; Wang, Chen ; Yin, Hang ; Han, Liang ; Yuan, C. -P. ( April 2022 , The European Physical Journal C)

   We propose a new observable for the measurement of the forward–backward asymmetry$$(A_{FB})$$$\left(A_{\mathrm{FB}}\right)$in Drell–Yan lepton production. At hadron colliders, the$$A_{FB}$$$A_{\mathrm{FB}}$distribution is sensitive to both the electroweak (EW) fundamental parameter$$\sin ^{2} \theta _{W}$$${sin}^2{\theta }_W$, the weak mixing angle, and the parton distribution functions (PDFs). Hence, the determination of$$\sin ^{2} \theta _{W}$$${sin}^2{\theta }_W$and the updating of PDFs by directly using the same$$A_{FB}$$$A_{\mathrm{FB}}$spectrum are strongly correlated. This correlation would introduce large bias or uncertainty into both precise measurements of EW and PDF sectors. In this article, we show that the sensitivity of$$A_{FB}$$$A_{\mathrm{FB}}$on$$\sin ^{2} \theta _{W}$$${sin}^2{\theta }_W$is dominated by its average value around theZpole region, while the shape (or gradient) of the$$A_{FB}$$$A_{\mathrm{FB}}$spectrum is insensitive to$$\sin ^{2} \theta _{W}$$${sin}^2{\theta }_W$and contains important information on the PDF modeling. Accordingly, a new observable related to the gradient of the spectrum is introduced, and demonstrated to be able to significantly reduce the potential bias on the determination of$$\sin ^{2} \theta _{W}$$${sin}^2{\theta }_W$when updating the PDFs using the same$$A_{FB}$$$A_{\mathrm{FB}}$data.

    

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2. Measurement of the mass dependence of the transverse momentum of lepton pairs in Drell–Yan production in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te\hspace{-.08em}V} $$

   https://doi.org/10.1140/epjc/s10052-023-11631-7  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Dragicevic, M. ; Valle, A. Escalante ; Frühwirth, R. ; Jeitler, M. ; Krammer, N. ; et al ( July 2023 , The European Physical Journal C)

   The double differential cross sections of the Drell–Yan lepton pair ($$\ell ^+\ell ^-$$${\ell }^{+}{\ell }^{-}$, dielectron or dimuon) production are measured as functions of the invariant mass$$m_{\ell \ell }$$$m_{\ell \ell }$, transverse momentum$$p_{\textrm{T}} (\ell \ell )$$$p_{\text{T}}\left(\ell \ell \right)$, and$$\varphi ^{*}_{\eta }$$${\phi }_{\eta }^{\ast }$. The$$\varphi ^{*}_{\eta }$$${\phi }_{\eta }^{\ast }$observable, derived from angular measurements of the leptons and highly correlated with$$p_{\textrm{T}} (\ell \ell )$$$p_{\text{T}}\left(\ell \ell \right)$, is used to probe the low-$$p_{\textrm{T}} (\ell \ell )$$$p_{\text{T}}\left(\ell \ell \right)$region in a complementary way. Dilepton masses up to 1$$\,\text {Te\hspace{-.08em}V}$$$\text{Te}\text{V}$are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various$$m_{\ell \ell }$$$m_{\ell \ell }$ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3$$\,\text {fb}^{-1}$$${\text{fb}}^{-1}$of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13$$\,\text {Te\hspace{-.08em}V}$$$\text{Te}\text{V}$. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.

    

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3. Charmed and ϕ meson decay constants from 2+1-flavor lattice QCD *

   https://doi.org/10.1088/1674-1137/abcd8f  

   Chen, Ying ; Chiu, Wei-Feng ; Gong, Ming ; Liu, Zhaofeng ; Ma, Yunheng ( February 2021 , Chinese Physics C)

   On a lattice with 2+1-flavor dynamical domain-wall fermions at the physical pion mass, we calculate the decay constants of,, and. The lattice size is, which corresponds to a spatial extension offm, with a lattice spacing offm. For the valence light, strange, and charm quarks, we use overlap fermions at several mass points close to their physical values. Our results at the physical point areMeV,MeV,MeV,MeV, andMeV. The couplings ofandto the tensor current () can be derived from ratiosand, respectively, which are the first lattice quantum chromodynamics (QCD) results. We also obtain ratiosand, which reflect the size of heavy quark symmetry breaking in charmed mesons. Ratiosandcan be taken as a measure ofSU(3) flavor symmetry breaking.

    

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4. Patchy Kinetic Sunyaev–Zel’dovich Effect with Controlled Reionization History and Morphology

   https://doi.org/10.3847/1538-4357/ac8481  

   Chen, Nianyi ; Trac, Hy ; Mukherjee, Suvodip ; Cen, Renyue ( February 2023 , The Astrophysical Journal)

   Using the novel semi-numerical code for reionization AMBER, we model the patchy kinetic Sunyaev–Zel’dovich (kSZ) effect by directly specifying the reionization history with the redshift midpointz_mid, duration Δ_z, and asymmetryA_z. We further control the ionizing sources and radiation through the minimum halo massM_hand the radiation mean free pathλ_mfp. AMBER reproduces the free-electron number density and the patchy kSZ power spectrum of radiation–hydrodynamic simulations at the target resolution (1 Mpch⁻¹) with matched reionization parameters. With a suite of (2 Gpc/h)³simulations using AMBER, we first constrain the redshift midpoint 6.0 <z_mid< 8.9 using the Planck 2018 Thomson optical depth result (95% CL). Then, assumingz_mid= 8, we find that the amplitude of$D_{\mathit{\ell }=3000}^{\mathrm{pkSZ}}$scales linearly with the duration of reionization Δ_zand is consistent with the 1σupper limit from South Pole Telescope (SPT) results up to Δ_z< 5.1 (Δ_zencloses 5%–95% ionization). Moreover, a shorterλ_mfpcan lead to a ∼10% lower$D_{\mathit{\ell }=3000}^{\mathrm{pkSZ}}$and a flatter slope in the$D_{\mathit{\ell }=3000}^{\mathrm{pkSZ}}-{\mathrm{\Delta }}_z$scaling relation, thereby affecting the constraints on Δ_zatℓ= 3000. Allowingz_midandλ_mfpto vary simultaneously, we get spectra consistent with the SPT result (95% CL) up to Δ_z= 12.8 (butA_z> 8 is needed to ensure the end of reionization beforez= 5.5). We show that constraints on the asymmetry require ∼0.1μk²measurement accuracy at multipoles other thanℓ= 3000. Finally, we find that the amplitude and shape of the kSZ spectrum are only weakly sensitive toM_hunder a fixed reionization history and radiation mean free path.

    

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5. Detection of Cosmological 21 cm Emission with the Canadian Hydrogen Intensity Mapping Experiment

   https://doi.org/10.3847/1538-4357/acb13f  

   The CHIME Collaboration ; Amiri, Mandana ; Bandura, Kevin ; Chen, Tianyue ; Deng, Meiling ; Dobbs, Matt ; Fandino, Mateus ; Foreman, Simon ; Halpern, Mark ; Hill, Alex S. ; et al ( April 2023 , The Astrophysical Journal)

   We present a detection of 21 cm emission from large-scale structure (LSS) between redshift 0.78 and 1.43 made with the Canadian Hydrogen Intensity Mapping Experiment. Radio observations acquired over 102 nights are used to construct maps that are foreground filtered and stacked on the angular and spectral locations of luminous red galaxies (LRGs), emission-line galaxies (ELGs), and quasars (QSOs) from the eBOSS clustering catalogs. We find decisive evidence for a detection when stacking on all three tracers of LSS, with the logarithm of the Bayes factor equal to 18.9 (LRG), 10.8 (ELG), and 56.3 (QSO). An alternative frequentist interpretation, based on the likelihood ratio test, yields a detection significance of 7.1σ(LRG), 5.7σ(ELG), and 11.1σ(QSO). These are the first 21 cm intensity mapping measurements made with an interferometer. We constrain the effective clustering amplitude of neutral hydrogen (Hi), defined as${\mathit{}}_{\mathrm{H}\mathrm{I}}\equiv {10}^3{\mathrm{\Omega }}_{\mathrm{H}\mathrm{I}}\left(b_{\mathrm{H}\mathrm{I}}+〈f{\mu }^2〉\right)$, where Ω_Hiis the cosmic abundance of Hi,b_Hiis the linear bias of Hi, and 〈fμ²〉 = 0.552 encodes the effect of redshift-space distortions at linear order. We find${\mathit{}}_{\mathrm{H}\mathrm{I}}={1.51}_{-0.97}^{+3.60}$for LRGs (z= 0.84),${\mathit{}}_{\mathrm{H}\mathrm{I}}={6.76}_{-3.79}^{+9.04}$for ELGs (z= 0.96), and${\mathit{}}_{\mathrm{H}\mathrm{I}}={1.68}_{-0.67}^{+1.10}$for QSOs (z= 1.20), with constraints limited by modeling uncertainties at nonlinear scales. We are also sensitive to bias in the spectroscopic redshifts of each tracer, and we find a nonzero bias Δv= − 66 ± 20 km s⁻¹for the QSOs. We split the QSO catalog into three redshift bins and have a decisive detection in each, with the upper bin atz= 1.30 producing the highest-redshift 21 cm intensity mapping measurement thus far.

    

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