We present a phenomenological extraction of transversity distribution functions and Collins fragmentation functions by simultaneously fitting to semi-inclusive deep inelastic scattering and electron-positron annihilation data. The analysis is performed within the transverse-momentum-dependent factorization formalism, and sea quark transversity distributions are taken into account for the first time. We find the <math><mover><mi>u</mi><mo>¯</mo></mover></math> quark favors a negative transversity distribution, while that of the <math><mover><mi>d</mi><mo>¯</mo></mover></math> quark is consistent with zero according to the current accuracy. In addition, based on a combined analysis of world data and simulated data, we quantitatively demonstrate the impact of the proposed Electron-Ion Collider in China on precise determinations of the transversity distributions, especially for sea quarks, and the Collins fragmentation functions.

China

Chunhua Zeng

Hongxin Dong

Tianbo Liu

Peng Sun

Yuxiang Zhao

Role of sea quarks in the nucleon transverse spin

We propose to utilize the exclusive Z-boson rare decays <math><mi>Z</mi><mo>→</mo><mi>ϒ</mi><mo>(</mo><mi>n</mi><mi>s</mi><mo>)</mo><mo>+</mo><mi>γ</mi></math> to constrain the <math><mi>Z</mi><mi>b</mi><mover><mrow><mi>b</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> couplings at the HL-LHC and 100 TeV proton-proton collider. We demonstrate that the event yield of the proposed processes is sensitive to the axial-vector component of the <math><mi>Z</mi><mi>b</mi><mover><mrow><mi>b</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> coupling and can provide complementary information to the jet-charge weighted single-spin asymmetry measurement at the EIC and the <math><mi>g</mi><mi>g</mi><mo>→</mo><mi>Z</mi><mi>h</mi></math> production rate measurement at the LHC. By applying the NRQCD factorization formalism, we calculate the partial decay width of <math><mi>Z</mi><mo>→</mo><mi>ϒ</mi><mo>(</mo><mi>n</mi><mi>s</mi><mo>)</mo><mo>+</mo><mi>γ</mi></math> to the NLO accuracy in strong interaction, which is found to agree with those obtained from the light-cone distribution amplitude approach. We show that the HL-LHC can break the degeneracy of the <math><mi>Z</mi><mi>b</mi><mover><mrow><mi>b</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> couplings, as implied by the precision electroweak data at LEP and SLC, if the signal efficiency can be improved by a factor of 1.7 from the present ATLAS analysis at the 13 TeV LHC with an integrated luminosity of <math><mn>36.1</mn><mspace width="0.25em"></mspace><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>.

United States

Bin Yan

C.P. Yuan

Probing the Anomalous Couplings via Exclusive Boson Decay

It is well known that the precise measurement of <math><mrow><mi>H</mi><mo>→</mo><mi>γ</mi><mi>γ</mi></mrow></math> can generate two degenerate parameter spaces of <math><mi>H</mi><mi>γ</mi><mi>γ</mi></math> anomalous coupling. We propose to utilize the exclusive Higgs rare decays <math><mrow><mi>H</mi><mo>→</mo><mi>ϒ</mi><mo>(</mo><mi>n</mi><mi>s</mi><mo>)</mo><mo>+</mo><mi>γ</mi></mrow></math> to break above mentioned degeneracy and further to constrain the <math><mi>H</mi><mi>γ</mi><mi>γ</mi></math> anomalous coupling at the HL-LHC. We demonstrate that the branching ratios of <math><mrow><mi>H</mi><mo>→</mo><mi>ϒ</mi><mo>(</mo><mi>n</mi><mi>s</mi><mo>)</mo><mo>+</mo><mi>γ</mi></mrow></math> can be significantly enhanced in the non-SM-like parameter space from <math><mi>H</mi><mo>→</mo><mi>γ</mi><mi>γ</mi></math> measurement, due to the destructive interference between the direct and indirect production of <math><mi>ϒ</mi><mo>(</mo><mi>n</mi><mi>s</mi><mo>)</mo></math> in the SM. By applying the NRQCD factorization formalism, we calculate the partial decay widths of <math><mrow><mi>H</mi><mo>→</mo><mi>ϒ</mi><mo>(</mo><mi>n</mi><mi>s</mi><mo>)</mo><mo>+</mo><mi>γ</mi></mrow></math> at the NLO accuracy of <math><msub><mi>α</mi><mi>s</mi></msub></math>. We show that it is hopeful to break such degenerate parameter space at the HL-LHC if we can further highly suppress the background and enhance the signal efficiency compared to the ATLAS preliminary simulation.

Probing the <math><mi>H</mi><mi>γ</mi><mi>γ</mi></math> coupling via Higgs boson exclusive decay into quarkonia plus a photon at the HL-LHC