Feynman loop integrals are a key ingredient for the calculation of higher order radiation effects, and are responsible for reliable and accurate theoretical prediction. We improve the efficiency of numerical integrati...Feynman loop integrals are a key ingredient for the calculation of higher order radiation effects, and are responsible for reliable and accurate theoretical prediction. We improve the efficiency of numerical integration in sector decomposition by implementing a quasi-Monte Carlo method associated with the CUDA/GPU technique. For demonstration we present the results of several Feynman integrals up to two loops in both Euclidean and physical kinematic regions in comparison with those obtained from FIESTA3. It is shown that both planar and non-planar two-loop master integrals in the physical kinematic region can be evaluated in less than half a minute with O(10^(-3))accuracy, which makes the direct numerical approach viable for precise investigation of higher order effects in multiloop processes, e.g. the next-to-leading order QCD effect in Higgs pair production via gluon fusion with a finite top quark mass.展开更多
In this study,we investigate the invariant-mass distribution of top-quark pairs near the 2mt threshold,which strongly influences the determination of the top-quark mass mt.Higher-order non-relativistic corrections lea...In this study,we investigate the invariant-mass distribution of top-quark pairs near the 2mt threshold,which strongly influences the determination of the top-quark mass mt.Higher-order non-relativistic corrections lead to large contributions,which are not included in the state-of-the-art theoretical predictions.A factorization formula is derived to resum such corrections to all orders in the strong-coupling,and necessary ingredients are calculated to perform the resummation at next-to-leading power.We combine the resummation with fixed-order results and present phenomenologically relevant numerical results.The resummation effect significantly increases the differential cross-section in the threshold region and makes the theoretical prediction more compatible with experimental data.We estimate that using our prediction in the determination of mt will lead to a value closer to the direct measurement result.展开更多
基金Supported by the Natural Science Foundation of China(11305179 11475180)Youth Innovation Promotion Association,CAS,IHEP Innovation(Y4545170Y2)+1 种基金State Key Lab for Electronics and Particle Detectors,Open Project Program of State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,China(Y4KF061CJ1)Cluster of Excellence Precision Physics,Fundamental Interactions and Structure of Matter(PRISMA-EXC 1098)
文摘Feynman loop integrals are a key ingredient for the calculation of higher order radiation effects, and are responsible for reliable and accurate theoretical prediction. We improve the efficiency of numerical integration in sector decomposition by implementing a quasi-Monte Carlo method associated with the CUDA/GPU technique. For demonstration we present the results of several Feynman integrals up to two loops in both Euclidean and physical kinematic regions in comparison with those obtained from FIESTA3. It is shown that both planar and non-planar two-loop master integrals in the physical kinematic region can be evaluated in less than half a minute with O(10^(-3))accuracy, which makes the direct numerical approach viable for precise investigation of higher order effects in multiloop processes, e.g. the next-to-leading order QCD effect in Higgs pair production via gluon fusion with a finite top quark mass.
基金Supported in part by the National Natural Science Foundation of China(11975030,11635001,11575004)W.-L.Ju was Supported in part by the China Postdoctoral Science Foundation(2017M610685)。
文摘In this study,we investigate the invariant-mass distribution of top-quark pairs near the 2mt threshold,which strongly influences the determination of the top-quark mass mt.Higher-order non-relativistic corrections lead to large contributions,which are not included in the state-of-the-art theoretical predictions.A factorization formula is derived to resum such corrections to all orders in the strong-coupling,and necessary ingredients are calculated to perform the resummation at next-to-leading power.We combine the resummation with fixed-order results and present phenomenologically relevant numerical results.The resummation effect significantly increases the differential cross-section in the threshold region and makes the theoretical prediction more compatible with experimental data.We estimate that using our prediction in the determination of mt will lead to a value closer to the direct measurement result.