Two factorization approaches have been proposed for single transverse spin asymmetries. One is the cofiinear factorization, the other is the transverse-momentum-dependent factorization. They have been previously deriv...Two factorization approaches have been proposed for single transverse spin asymmetries. One is the cofiinear factorization, the other is the transverse-momentum-dependent factorization. They have been previously derived in a formal way by using diagram expansion at hadron level. If the two factorizations hold or can be proven, they should also hold when we replace hadrons with patton states. We examine these two factorizations at patton level with massless partons. It is nontrivial to generate these asymmetries at parton level with massless patrons because the asymmetries require helicity-flip and nonzero absorptive parts in scattering amplitudes. By constructing suitable patton states with massless partons we derive the two factorizations for the asymmetry in Drell-Yan processes. It is found from our results that the collinear factorization derived at parton level is not the same as that derived at hadron level. Our results with massless partons confirm those derived with single massive parton state in our previous works.展开更多
Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum ...Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum of J/ψ pairs is studied.A narrow structure around 6:9 GeV=c^2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed.The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6:2 and 7:4 GeV=c^2,covering predicted masses of states composed of four charm quarks.The mass and natural width of the narrow X(6900)structure are measured assuming a Breit-Wigner lineshape.展开更多
Models of circadian genetic oscillators involving interlinked feedback processes in molecular level genetic networks in Drosophila melanogaster and Neurospora crassa are studied, and mechanisms whereby synchronization...Models of circadian genetic oscillators involving interlinked feedback processes in molecular level genetic networks in Drosophila melanogaster and Neurospora crassa are studied, and mechanisms whereby synchronization can arise in an assembly of cells are examined. The individual subcellular circadian oscillatory processes are stochastic in nature due to the small numbers of molecules that are involved, and are subject to large fluctuations. The authors investigate and present the simulations of the stochastic dynamics of ensembles of clock-regulating proteins in different nuclei that communicate via ancillary small molecules, environmental parameters, additive cellular noise, or through diffusive processes. The results show that the emergence of collective oscillations is a macroscopic observable which has its origins in the microscopic coupling between distinct cellular oscillators.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos. 10721063, 10575126, and 10975169
文摘Two factorization approaches have been proposed for single transverse spin asymmetries. One is the cofiinear factorization, the other is the transverse-momentum-dependent factorization. They have been previously derived in a formal way by using diagram expansion at hadron level. If the two factorizations hold or can be proven, they should also hold when we replace hadrons with patton states. We examine these two factorizations at patton level with massless partons. It is nontrivial to generate these asymmetries at parton level with massless patrons because the asymmetries require helicity-flip and nonzero absorptive parts in scattering amplitudes. By constructing suitable patton states with massless partons we derive the two factorizations for the asymmetry in Drell-Yan processes. It is found from our results that the collinear factorization derived at parton level is not the same as that derived at hadron level. Our results with massless partons confirm those derived with single massive parton state in our previous works.
基金support from CERNfrom the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil)+20 种基金MOST and NSFC (China)CNRS/IN2P3 (France)BMBF, DFG and MPG (Germany)INFN (Italy)NWO (Netherlands)MNiSW and NCN (Poland)MEN/IFA (Romania)MSHE (Russia)MinECo (Spain)SNSF and SER (Switzerland)NASU (Ukraine)STFC (United Kingdom)DOE NP and NSF (USA)AvH Foundation (Germany)EPLANET, Marie Sklodowska-Curie Actions and ERC (European Union)A^(*)MIDEX, ANR, Labex P2IO and OCEVU, and Region Auvergne-Rhone-Alpes (France)Key Research Program of Frontier Sciences of CAS, CAS PIFIthe Thousand Talents Program (China)RFBR, RSF and Yandex LLC (Russia)GVA, XuntaGal and GENCAT (Spain)the Royal Society and the Leverhulme Trust (United Kingdom)。
文摘Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum of J/ψ pairs is studied.A narrow structure around 6:9 GeV=c^2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed.The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6:2 and 7:4 GeV=c^2,covering predicted masses of states composed of four charm quarks.The mass and natural width of the narrow X(6900)structure are measured assuming a Breit-Wigner lineshape.
文摘Models of circadian genetic oscillators involving interlinked feedback processes in molecular level genetic networks in Drosophila melanogaster and Neurospora crassa are studied, and mechanisms whereby synchronization can arise in an assembly of cells are examined. The individual subcellular circadian oscillatory processes are stochastic in nature due to the small numbers of molecules that are involved, and are subject to large fluctuations. The authors investigate and present the simulations of the stochastic dynamics of ensembles of clock-regulating proteins in different nuclei that communicate via ancillary small molecules, environmental parameters, additive cellular noise, or through diffusive processes. The results show that the emergence of collective oscillations is a macroscopic observable which has its origins in the microscopic coupling between distinct cellular oscillators.
