We report some applications of QCD light cone sum rules(LCSR)to B meson weak decays.Special emphasis is on estimates of the form factors for B decays into a pseudoscalar(P)/vector(V)meson,with a certain chiral current...We report some applications of QCD light cone sum rules(LCSR)to B meson weak decays.Special emphasis is on estimates of the form factors for B decays into a pseudoscalar(P)/vector(V)meson,with a certain chiral current correlator.The main new ingredient,as compared with the case of the standard correlators,is that in the operator product expansion calculations,the contributions due to the twist-3 distribution amplitudes of the related light mesons,which are less known and would bring a larger uncertainty to the calculations with the standard correlators,cancel out fully in the B!P case and do out partially in the B!V one.An important observation,which is similar to that in soft collinear effective theory,is made in twist-3 approximation:whereas only one independent form factor is needed for parameterizing the hadronic matrix elements for a B!P transition induced by all the relevant heavy-light quark currents,there exist two independent form factors under the condition of neglecting the terms suppressed by a factor of m2V,for the B!V transition.Therefore,the improved LCSR approach could be of stronger predictive power for the weak form factors.Also,this approach is employed to understand the B!D transitions by introducing a leading twist-2 DA for an energetic D meson,combined with some of other QCDbased approaches.A detailed QCD next-to-leading order calculation of the B!p form factors is presented for an illustrative purpose,and the sum rule results are used to extract the Cabibbo–Kobayashi–Maskawa matrix element jVubj from the latest BaBar data.展开更多
Bilingual education has more than 50-years' history in the world.It has gained the attention from the world since 1960s in some western countries,such as the USA and Canada.With the growth of international busines...Bilingual education has more than 50-years' history in the world.It has gained the attention from the world since 1960s in some western countries,such as the USA and Canada.With the growth of international business and the appearance of the global village,bilingual education has become a hot issue in China.This article generally outlines the picture of bilingual education in the world.Then,it describes the development of bilingualism under Chinese contexts.Above all,the models of the bilingual education have been explicitly introduced to build up the basis for further investigation.Besides,the two main periods of the bilingual education in China have been described based on the empirical literature.In the end,the influential factors of the development of bilingual education have been discussed from five main perspectives:economic,social,educational,cultural and political framework.However,there is a lack of documentary resources and experimental materials for the scaffolding of bilingual education in China,which requires further investigation.展开更多
In this work the neutral-current scattering cross-section for neutrinos on electrons is calculated assuming that a massive Dirac neutrino is characterized by a phenomenological parameters, a charge radius 2> and th...In this work the neutral-current scattering cross-section for neutrinos on electrons is calculated assuming that a massive Dirac neutrino is characterized by a phenomenological parameters, a charge radius 2> and the right-handed currents are present in the framework of a Left-Right symmetric model (LR). Using the CHARM II result for the charge radius of the muon-neutrino |2>|<6.0×10-33cm2, we place a bound on -7.9×10-33cm2≤2>LR≤7.9×10-33cm2. We discuss the relationship between the electron neutral couplings gVeV and gVeA and the LR model parameters. We also estimate a bound on the heavy massive neutral vector boson mass MZR>650GeV of the LR model. These results have never been reported in the literature before and could have practical or theoretical interest, such as in the case of the neutrinos produced in core-collapse supernova explosions, that is to say, right-handed Dirac neutrinos emission from supernova core vLe-→vRe-.展开更多
By comparing the cross Sections for left-and right-handed electrons scattered from various unpolarized nuclear targets,the small parity-violating asymmetry can be measured.These asymmetry data probe a wide variety of ...By comparing the cross Sections for left-and right-handed electrons scattered from various unpolarized nuclear targets,the small parity-violating asymmetry can be measured.These asymmetry data probe a wide variety of important topies,including searches for new fundamental interactions and important features of nuclear structure that cannot be studied with other probes.A special feature of these experiments is that the results are interpreted with remarkably few theoretical uncertainties,which justifies pushing the experiments to the highest possible precision.To measure the small asymmetries accurately,a number of novel experimental techniques have been developed.展开更多
基金supported by the National Natural Science Foundation of China (11235005)
文摘We report some applications of QCD light cone sum rules(LCSR)to B meson weak decays.Special emphasis is on estimates of the form factors for B decays into a pseudoscalar(P)/vector(V)meson,with a certain chiral current correlator.The main new ingredient,as compared with the case of the standard correlators,is that in the operator product expansion calculations,the contributions due to the twist-3 distribution amplitudes of the related light mesons,which are less known and would bring a larger uncertainty to the calculations with the standard correlators,cancel out fully in the B!P case and do out partially in the B!V one.An important observation,which is similar to that in soft collinear effective theory,is made in twist-3 approximation:whereas only one independent form factor is needed for parameterizing the hadronic matrix elements for a B!P transition induced by all the relevant heavy-light quark currents,there exist two independent form factors under the condition of neglecting the terms suppressed by a factor of m2V,for the B!V transition.Therefore,the improved LCSR approach could be of stronger predictive power for the weak form factors.Also,this approach is employed to understand the B!D transitions by introducing a leading twist-2 DA for an energetic D meson,combined with some of other QCDbased approaches.A detailed QCD next-to-leading order calculation of the B!p form factors is presented for an illustrative purpose,and the sum rule results are used to extract the Cabibbo–Kobayashi–Maskawa matrix element jVubj from the latest BaBar data.
文摘Bilingual education has more than 50-years' history in the world.It has gained the attention from the world since 1960s in some western countries,such as the USA and Canada.With the growth of international business and the appearance of the global village,bilingual education has become a hot issue in China.This article generally outlines the picture of bilingual education in the world.Then,it describes the development of bilingualism under Chinese contexts.Above all,the models of the bilingual education have been explicitly introduced to build up the basis for further investigation.Besides,the two main periods of the bilingual education in China have been described based on the empirical literature.In the end,the influential factors of the development of bilingual education have been discussed from five main perspectives:economic,social,educational,cultural and political framework.However,there is a lack of documentary resources and experimental materials for the scaffolding of bilingual education in China,which requires further investigation.
文摘In this work the neutral-current scattering cross-section for neutrinos on electrons is calculated assuming that a massive Dirac neutrino is characterized by a phenomenological parameters, a charge radius 2> and the right-handed currents are present in the framework of a Left-Right symmetric model (LR). Using the CHARM II result for the charge radius of the muon-neutrino |2>|<6.0×10-33cm2, we place a bound on -7.9×10-33cm2≤2>LR≤7.9×10-33cm2. We discuss the relationship between the electron neutral couplings gVeV and gVeA and the LR model parameters. We also estimate a bound on the heavy massive neutral vector boson mass MZR>650GeV of the LR model. These results have never been reported in the literature before and could have practical or theoretical interest, such as in the case of the neutrinos produced in core-collapse supernova explosions, that is to say, right-handed Dirac neutrinos emission from supernova core vLe-→vRe-.
基金Department of Energy(DOE)under grants DE-FG02-84ER40146(PAS)DE-FG02-07ER41522(KDP).
文摘By comparing the cross Sections for left-and right-handed electrons scattered from various unpolarized nuclear targets,the small parity-violating asymmetry can be measured.These asymmetry data probe a wide variety of important topies,including searches for new fundamental interactions and important features of nuclear structure that cannot be studied with other probes.A special feature of these experiments is that the results are interpreted with remarkably few theoretical uncertainties,which justifies pushing the experiments to the highest possible precision.To measure the small asymmetries accurately,a number of novel experimental techniques have been developed.
