The effect of bending pre-strain and pressure on the forming behavior of AA5052-H32 sheets has been studied using a shock tube. Various forming parameters like dome height, effective strain and stress distribution, ha...The effect of bending pre-strain and pressure on the forming behavior of AA5052-H32 sheets has been studied using a shock tube. Various forming parameters like dome height, effective strain and stress distribution, hardness, and grain size evolution have been measured. Circular grids are printed on the sheets and Hill’s 1948 yield criterion is used to calculate the effective strain distribution. The effective stress distribution is calculated by using the Hollomon’s power law. The strain evolution during the forming process is monitored by mounting a strain rosette at the mid location of the sheet. The strain-time graph confirms the sharp rise in the peak strain and it increases significantly at higher pressure. The variation in the forming parameters asserts that the material stretches uniformly without strain localization. The optical microstructures also depict that the equiaxed grains are stretched and elongated after the shock deformation. This analysis confirms that the forming behavior of the material is dependent both on the degree of pre-strain and the change in pressure.展开更多
First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b-J/ψΛK-decays.The observed structure is consistent with being due to a charmonium pentaquark w...First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b-J/ψΛK-decays.The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1r including systematic uncertainties and lookelsewhere effect.Its mass and width are determined to be 4458:8±2:9t4:7-1:1 MeV and 17:3±6:5t8:0-5:7 MeV,respectively,where the quoted uncertainties are statistical and systematic.The structure is also consistent with being due to two resonances.In addition,the narrow excited■-states,N■(1690)and■(1820),are seen for the first time in a■b-decay,and their masses and widths are measured with improved precision.The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb-1,collected with the LHCb experiment at centre-of-mass energies of 7,8 and 13 TeV.展开更多
A first search for theΞbc+J/ψΞc+decay is performed by the LHCb experiment with a data sample of proton-proton collisions,corresponding to an integrated luminosity of 9 fb−1 recorded at centre-of-mass en...A first search for theΞbc+J/ψΞc+decay is performed by the LHCb experiment with a data sample of proton-proton collisions,corresponding to an integrated luminosity of 9 fb−1 recorded at centre-of-mass energies of 7,8,and 13 TeV.Two peaking structures are seen with a local(global)significance of 4.3(2.8)and 4.1(2.4)standard deviations at masses of 6571 and 6694 MeV/c2,respectively.Upper limits are set on theΞ+bc baryon production cross-section times the branching fraction relative to that of the B+c→J/ψD+s decay at centre-of-mass energies of 8 and 13 TeV,in theΞ+bc and in the B+c rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to 20GeV/c,respectively.Upper limits are presented as a function of theΞ+bc mass and lifetime.展开更多
The production ofΞcc++baryons in proton-proton collisions at a centre-of-mass energy of s1/2=13 TeV is measured in the transverse-momentum range 4<pT<15 GeV/c and the rapidity range 2.0<y<4.5.The data use...The production ofΞcc++baryons in proton-proton collisions at a centre-of-mass energy of s1/2=13 TeV is measured in the transverse-momentum range 4<pT<15 GeV/c and the rapidity range 2.0<y<4.5.The data used in this measurement correspond to an integrated luminosity of 1.7 fb-1,recorded by the LHCb experiment during2016.The ratio of theΞcc++production cross-section times the branching fraction of theΞcc++→Λc+K-π+π+decay relative to the promptΛc+production cross-section is found to be(2.22±0.27±0.29)×10-4,assuming the central value of the measuredΞcc++lifetime,where the first uncertainty is statistical and the second systematic.展开更多
A search for the rare decays W+→Ds+γand Z→D0γis performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV,corresponding to an integrated luminosity ...A search for the rare decays W+→Ds+γand Z→D0γis performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV,corresponding to an integrated luminosity of 2.0fb−1.No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W+→Ds+γand Z→μ+μ−decays as normalization channels.The upper limits are 6.5×10−4and 2.1×10−3at 95%confidence level for the W+→Ds+γand Z→D0γdecay modes,respectively.This is the first reported search for the Z→D0γdecay,while the upper limit on the W+→D+sγbranching fraction improves upon the previous best limit.展开更多
A search for the rare decay B0→J/ψФis performed using Pp collision data collected with the LHCb dete-ctor at centre-of-mass energies of 7,8 and 13 TeV,corresponding to an integrated luminosity of9 fb.No signific...A search for the rare decay B0→J/ψФis performed using Pp collision data collected with the LHCb dete-ctor at centre-of-mass energies of 7,8 and 13 TeV,corresponding to an integrated luminosity of9 fb.No significant signal of the decay is observed and an upper limitof 1.1x 10-7at 90%confidence level is set on the branching fraction.展开更多
The first search for the doubly heavyΩ0bcbaryon and a search for the E0bcbaryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13 T...The first search for the doubly heavyΩ0bcbaryon and a search for the E0bcbaryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.2 fb-1.The baryons are reconstructed via their decays toΛ+cπ-and E+cπ-.No significant excess is fbund for invariant masses between 6700 and 7300 MeV/c2,in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c.Upper limits are set on the ratio of theΩ0bcand E0bcproduction cross-section times the branching fraction toΛ+cπ-(E+cπ-)relative to that of theΛ0b(E0b)baryon,for different lifetime hypotheses,at 95%confidence level.The upper limits range from 0.5 x 10-4to 2.5 x 10-4for theΩ0bc→Λ+cπ-(E0bc→Λ+cπ-)decay,and from 1.4x 10-3to 6.9 x 10-3for theΩ0bc→E+cπ-(E0bc→E+cπ-)decay,depending on the considered mass and lifetime of theΩ0bc(E0bc)baryon.展开更多
We study the multisubband electron mobility in a barrier delta doped AlχGal-χAs parabolic quantum well structure under the influence of an applied electric field perpendicular to the interface plane. We consider the...We study the multisubband electron mobility in a barrier delta doped AlχGal-χAs parabolic quantum well structure under the influence of an applied electric field perpendicular to the interface plane. We consider the alloy fraction χ = 0.3 for barriers and vary x from 0.0 to 0.1 for the parabolic well. Electrons diffuse into the well and confine within the triangular like potentials near the interfaces due to Coulomb interaction with ionized donors. The parabolic structure potential, being opposite in nature, partly compensates the Coulomb potential. The external electric field further amends the potential structure leading to an asymmetric potential profile. Accordingly the energy levels, wave functions and occupation of subbands change. We calculate low temperature electron mobility as a function of the electric field and show that when two subbands are occupied, the mobility is mostly dominated by ionised impurity scattering mediated by intersubband effects. As the field increases transition from double subband to single subband occupancy occurs. A sudden enhancement in mobility is obtained due to curtailment of intersubband effects. Thereafter the mobility is governed by both impurity and alloy disorder scatterings. Our analysis of mobility as a function of the electric field for different structural parameters shows interesting results.展开更多
基金‘‘Aeronautical Research and Development Board (AR & DB) India” for the financial support towards the fabrication of the shock tube experimental facility at IIT Guwahati
摘要The effect of bending pre-strain and pressure on the forming behavior of AA5052-H32 sheets has been studied using a shock tube. Various forming parameters like dome height, effective strain and stress distribution, hardness, and grain size evolution have been measured. Circular grids are printed on the sheets and Hill’s 1948 yield criterion is used to calculate the effective strain distribution. The effective stress distribution is calculated by using the Hollomon’s power law. The strain evolution during the forming process is monitored by mounting a strain rosette at the mid location of the sheet. The strain-time graph confirms the sharp rise in the peak strain and it increases significantly at higher pressure. The variation in the forming parameters asserts that the material stretches uniformly without strain localization. The optical microstructures also depict that the equiaxed grains are stretched and elongated after the shock deformation. This analysis confirms that the forming behavior of the material is dependent both on the degree of pre-strain and the change in pressure.
摘要First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b-J/ψΛK-decays.The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1r including systematic uncertainties and lookelsewhere effect.Its mass and width are determined to be 4458:8±2:9t4:7-1:1 MeV and 17:3±6:5t8:0-5:7 MeV,respectively,where the quoted uncertainties are statistical and systematic.The structure is also consistent with being due to two resonances.In addition,the narrow excited■-states,N■(1690)and■(1820),are seen for the first time in a■b-decay,and their masses and widths are measured with improved precision.The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb-1,collected with the LHCb experiment at centre-of-mass energies of 7,8 and 13 TeV.
基金The project support from CERN and from the national agencies:CAPES,CNPq,FAPERJ and FINEP(Brazil)MOST and NSFC(China)+18 种基金CNRS/IN2P3(France)BMBF,DFG and MPG(Germany)INFN(Italy)NWO(Netherlands)MNiSW and NCN(Poland)MEN/IFA(Romania)MICINN(Spain)SNSF and SER(Switzerland)NASU(Ukraine)STFC(United Kingdom)DOE NP and NSF(USA).We acknowledge the computing resources that are provided by CERN,IN2P3(France),KIT and DESY(Germany),INFN(Italy),SURF(Netherlands),PIC(Spain),GridPP(United Kingdom),CSCS(Switzerland),IFIN-HH(Romania),CBPF(Brazil),Polish WLCG(Poland)and NERSC(USA).Individual groups or members have received support from ARC and ARDC(Australia)Minciencias(Colombia)AvH Foundation(Germany)EPLANET,Marie Sklodowska-Curie Actions and ERC(European Union)A*MIDEX,ANR,IPhU and Labex P2IO,and Région Auvergne-RhôneAlpes(France)Key Research Program of Frontier Sciences of CAS,CAS PIFI,CAS CCEPP,Fundamental Research Funds for the Central Universities,and Sci.&Tech.Program of Guangzhou(China)GVA,XuntaGal,GENCAT and Prog.Atracción Talento,CM(Spain)SRC(Sweden)the Leverhulme Trust,the Royal Society and UKRI(United Kingdom).
摘要A first search for theΞbc+J/ψΞc+decay is performed by the LHCb experiment with a data sample of proton-proton collisions,corresponding to an integrated luminosity of 9 fb−1 recorded at centre-of-mass energies of 7,8,and 13 TeV.Two peaking structures are seen with a local(global)significance of 4.3(2.8)and 4.1(2.4)standard deviations at masses of 6571 and 6694 MeV/c2,respectively.Upper limits are set on theΞ+bc baryon production cross-section times the branching fraction relative to that of the B+c→J/ψD+s decay at centre-of-mass energies of 8 and 13 TeV,in theΞ+bc and in the B+c rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to 20GeV/c,respectively.Upper limits are presented as a function of theΞ+bc mass and lifetime.
基金Supported by CERNnational agencies:CAPES+30 种基金CNPqFAPERJFINEP(Brazil)MOSTNSFC(China)CNRS/IN2P3(France)BMBFDFGMPG(Germany)INFN(Italy)NWO(Netherlands)MNiSWNCN(Poland)MEN/IFA(Romania)MSHE(Russia)MinECo(Spain)SNSFSER(Switzerland)NASU(Ukraine)STFC(United Kingdom)DOE NPNSF(USA)Key Research Program of Frontier Sciences of CAS,CAS PIFIthe Thousand Talents Program(China)RFBRRSFYandex LLC(Russia)GVAXuntaGalGENCAT(Spain)the Royal Society and the Leverhulme Trust(United Kingdom)
摘要The production ofΞcc++baryons in proton-proton collisions at a centre-of-mass energy of s1/2=13 TeV is measured in the transverse-momentum range 4<pT<15 GeV/c and the rapidity range 2.0<y<4.5.The data used in this measurement correspond to an integrated luminosity of 1.7 fb-1,recorded by the LHCb experiment during2016.The ratio of theΞcc++production cross-section times the branching fraction of theΞcc++→Λc+K-π+π+decay relative to the promptΛc+production cross-section is found to be(2.22±0.27±0.29)×10-4,assuming the central value of the measuredΞcc++lifetime,where the first uncertainty is statistical and the second systematic.
摘要A search for the rare decays W+→Ds+γand Z→D0γis performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV,corresponding to an integrated luminosity of 2.0fb−1.No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W+→Ds+γand Z→μ+μ−decays as normalization channels.The upper limits are 6.5×10−4and 2.1×10−3at 95%confidence level for the W+→Ds+γand Z→D0γdecay modes,respectively.This is the first reported search for the Z→D0γdecay,while the upper limit on the W+→D+sγbranching fraction improves upon the previous best limit.
基金support from AvH Foundation(Germany)EPLANET,Marie Sk lodowska-Curie Actions and ERC(European Union)+11 种基金A*MIDEXANRLabex P2IOOCEVURégion Auvergne-Rh?ne-Alpes(France)Key Research Program of Frontier Sciences of CASCAS PIFIThousand Talents ProgramSci.&Tech.Program of Guangzhou(China)RFBR,RSF and Yandex LLC(Russia)GVA,Xunta Gal and GENCAT(Spain)the Royal Society and the Leverhulme Trust(United Kingdom)。
摘要A search for the rare decay B0→J/ψФis performed using Pp collision data collected with the LHCb dete-ctor at centre-of-mass energies of 7,8 and 13 TeV,corresponding to an integrated luminosity of9 fb.No significant signal of the decay is observed and an upper limitof 1.1x 10-7at 90%confidence level is set on the branching fraction.
基金CAPES,CNPq,FAPERJ and FINEP(Brazil)MOST and NSFC(China)+18 种基金CNRS/IN2P3(France)BMBF,DFG,MPG(Germany)INFN(Italy)NWO(Netherlands)MNiSW,NCN(Poland)MEN/IFA(Romania)MSHE(Russia)MICINN(Spain)SNSF,SER(Switzerland)NASU(Ukraine)STFC(United Kingdom)DOE NP,NSF(USA).We acknowledge the computing resources that are provided by CERN,IN2P3(France),KIT and DESY(Germany),INFN(Italy),SURF(Netherlands),PIC(Spain),GridPP(United Kingdom),RRCKI and Yandex LLC(Russia),CSCS(Switzerland),IFIN-HH(Romania),CBPF(Brazil),PL-GRID(Poland)and NERSC(USA)AvH Foundation(Germany)EPLANET,Marie Sklodowska-Curie Actions and ERC(European Union)A*MIDEX,ANR,Labex P2IO and OCEVU,Region Auvergne-Rhdne-Alpes(France)Key Research Program of Frontier Sciences of CAS,CAS PIFI,CAS CCEPP,Fundamental Research Funds for the Central Universities,and Sci.Tech.Program of Guangzhou(China)RFBR,RSF and Yandex LLC(Russia)GVA,XuntaGal,GENCAT(Spain)the Leverhulme Trust,the Royal Society and UKRI(United Kingdom)。
摘要The first search for the doubly heavyΩ0bcbaryon and a search for the E0bcbaryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.2 fb-1.The baryons are reconstructed via their decays toΛ+cπ-and E+cπ-.No significant excess is fbund for invariant masses between 6700 and 7300 MeV/c2,in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c.Upper limits are set on the ratio of theΩ0bcand E0bcproduction cross-section times the branching fraction toΛ+cπ-(E+cπ-)relative to that of theΛ0b(E0b)baryon,for different lifetime hypotheses,at 95%confidence level.The upper limits range from 0.5 x 10-4to 2.5 x 10-4for theΩ0bc→Λ+cπ-(E0bc→Λ+cπ-)decay,and from 1.4x 10-3to 6.9 x 10-3for theΩ0bc→E+cπ-(E0bc→E+cπ-)decay,depending on the considered mass and lifetime of theΩ0bc(E0bc)baryon.
摘要We study the multisubband electron mobility in a barrier delta doped AlχGal-χAs parabolic quantum well structure under the influence of an applied electric field perpendicular to the interface plane. We consider the alloy fraction χ = 0.3 for barriers and vary x from 0.0 to 0.1 for the parabolic well. Electrons diffuse into the well and confine within the triangular like potentials near the interfaces due to Coulomb interaction with ionized donors. The parabolic structure potential, being opposite in nature, partly compensates the Coulomb potential. The external electric field further amends the potential structure leading to an asymmetric potential profile. Accordingly the energy levels, wave functions and occupation of subbands change. We calculate low temperature electron mobility as a function of the electric field and show that when two subbands are occupied, the mobility is mostly dominated by ionised impurity scattering mediated by intersubband effects. As the field increases transition from double subband to single subband occupancy occurs. A sudden enhancement in mobility is obtained due to curtailment of intersubband effects. Thereafter the mobility is governed by both impurity and alloy disorder scatterings. Our analysis of mobility as a function of the electric field for different structural parameters shows interesting results.