A study of the difference in the CP asymmetries between Λ_(b)^(0)→J/ψpπ−and Λ_(b)^(0)→J/ψpK−decays,ΔA_(CP),is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–20...A study of the difference in the CP asymmetries between Λ_(b)^(0)→J/ψpπ−and Λ_(b)^(0)→J/ψpK−decays,ΔA_(CP),is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018,corresponding to an integrated luminosity of 6 fb−1.This quantity is measured to be ΔA_(CP)=(4.03±1.18±0.23)%,where the first uncertainty is statistical and the second is systematic.When combined with the previous LHCb result,a value of ΔA_(CP)=(4.31±1.06±0.28)% is obtained,corresponding to a significance of 3.9_(σ) against the CP symmetry hypothesis.Studies of triple-product asymmetries,which provide an additional probe of CP violation,show no significant deviation from CP symmetry.展开更多
An amplitude analysis of the Dsi(2460)+→D,π+π-transition is performed simultaneously in BO→D'D,π+π-,B+-D'D,π+π,and BO-D-D,π+π-decays.The study is based on a data sample of proton-proton collisions re...An amplitude analysis of the Dsi(2460)+→D,π+π-transition is performed simultaneously in BO→D'D,π+π-,B+-D'D,π+π,and BO-D-D,π+π-decays.The study is based on a data sample of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of Vs=7,8,and 13Tev,corresponding to a total integrated luminosity of 9fb-1.A clear double-peak structure is observed in the m(π+π~)spectrum of the Ds1(2460)+→D,π+π-decay.The data can be described either with a model including fo(500),o(980),and f2(1270)resonances,in which the contributions of fo(980)and f2(1270)are unexpectedly large,or with a model including fo(500),a doubly charged open-charm tetraquark state Tt and its isospin partner Tes.If the former is considered implausible,the Tes states are observed with high significance,and the data are consistent with isospin symmetry.When imposing isospin constraints between the two Tes states,their mass and width are determined to be(2327±13±13)Mev and(96±16+70)Mev,respectively,where the first uncertainty is statistical 23 and the second is systematic.The mass is slightly below the DK threshold,and a spin-parity of o+is favoured with high significance.展开更多
文摘A study of the difference in the CP asymmetries between Λ_(b)^(0)→J/ψpπ−and Λ_(b)^(0)→J/ψpK−decays,ΔA_(CP),is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018,corresponding to an integrated luminosity of 6 fb−1.This quantity is measured to be ΔA_(CP)=(4.03±1.18±0.23)%,where the first uncertainty is statistical and the second is systematic.When combined with the previous LHCb result,a value of ΔA_(CP)=(4.31±1.06±0.28)% is obtained,corresponding to a significance of 3.9_(σ) against the CP symmetry hypothesis.Studies of triple-product asymmetries,which provide an additional probe of CP violation,show no significant deviation from CP symmetry.
基金support from CERN and from the national agencies:CAPES,CNPq,FAPERJ and FINEP(Brazil)MOST and NSFC(China)+12 种基金CNRS/IN2P3(France)BMBF,DFG and MPG(Germany)INFN(Italy)NWO(Netherlands)MNi SW and NCN(Poland)MCID/IFA(Romania)MICIU and AEI(Spain)SNSF and SER(Switzerland)NASU(Ukraine)STFC(United Kingdom)DOE NP and NSF(USA)Key Research Program of Frontier Sciences of CAS,CAS PIFI,CAS CCEPP,Fundamental Research Funds for the Central UniversitiesSci.&Tech.Program of Guangzhou(China)。
文摘An amplitude analysis of the Dsi(2460)+→D,π+π-transition is performed simultaneously in BO→D'D,π+π-,B+-D'D,π+π,and BO-D-D,π+π-decays.The study is based on a data sample of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of Vs=7,8,and 13Tev,corresponding to a total integrated luminosity of 9fb-1.A clear double-peak structure is observed in the m(π+π~)spectrum of the Ds1(2460)+→D,π+π-decay.The data can be described either with a model including fo(500),o(980),and f2(1270)resonances,in which the contributions of fo(980)and f2(1270)are unexpectedly large,or with a model including fo(500),a doubly charged open-charm tetraquark state Tt and its isospin partner Tes.If the former is considered implausible,the Tes states are observed with high significance,and the data are consistent with isospin symmetry.When imposing isospin constraints between the two Tes states,their mass and width are determined to be(2327±13±13)Mev and(96±16+70)Mev,respectively,where the first uncertainty is statistical 23 and the second is systematic.The mass is slightly below the DK threshold,and a spin-parity of o+is favoured with high significance.
