Measurements of Normalized Differential Cross Sections of Inclusive η Production in e+e- Annihilation at Energy from 2.0000 to 3.6710 GeV

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e^{+}e^{-}→η+X, normalized by the total cross section of e^{+}e^{-}→hadrons, is measured at eight center-of-mass energy points from 2.0000 to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy compared to the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well

Measurements of normalized differential cross sections of inclusive annihilation at energy from 2.0000 to 3.6710 GeV

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e+e−→η+X, normalized by the total cross section of e+e−→hadrons, is measured at eight center-of-mass energy points from 2.0000 GeV to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy from calculations with the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well

CEPC Technical Design Report: Accelerator

The Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, al.l GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and tt). The Linac and Damping Ring are situated on the surface, while the subterranean Booster and Collider are housed ina100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs fketory. In its baseline design with synchrotron radiation (SR) power of30 MW per beam, it can achieve a luminosity of 5 x1034 cm-2s-1 per interaction point (IP), resulting in an integrated luminosity of 13 ab 1 for two IPs over a decade, producing 2.6millionHiggsbosons. IncreasingtheSRpowerto 50MWperbeam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements ofHiggs coupling at sub-percent levels, exceeding the precision expected from the HLLHCbyanorderofmagnitude. This Technical Design Report(TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout, performance metrics, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments and data collection could potentially be initiated in the mid-2030s