摘要:

AbstractFixed‐target experiments permit the study of hadron production in the target fragmentation region. It is expected that the tagging of specific particles in the target fragments can be employed to introduce a bias in the hard scattering process towards a specific flavour content. The case of hadrons containing a heavy quark is particularly attractive because of the clear experimental signatures and the applicability of perturbative QCD. The standard approach to one‐particle inclusive processes based on fragmentation functions is valid in the current fragmentation region and for large transverse momentapTin the target fragmentation region, but it fails for particle production at smallpTin the target fragmentation region. A collinear singularity, which cannot be absorbed in the standard way into the phenomenological distribution functions, prohibits the application of this procedure. This situation is remedied by the introduction of a new set of distribution functions, the target fragmentation functions. They describe particle production in the target fragmentation region, and can be viewed as correlated distribution functions in the momentum fractions of the observed particle and of the parton initiating the hard scattering process. It is shown in a next‐to‐leading‐order calculation for the case of deeply inelastic lepton‐nucleon scattering that the additional singularity can be consistently absorbed into the renormalized target fragmentation functions on the one‐loop level. The formalism is derived in detail and is applied to the production of heavy quarks. The renormalization group equation of the target fragmentation functions for the perturbative contribution is solved numerically, and the results of a case study for deeply inelastic lepton‐nucleon scattering at DESY (H1 and ZEUS at HERA), at CERN (NA47) and at Fermilab (E665) are discussed. We also comment briefly on the case of an intrinsic heavy‐quark cont

ISSN:0015-8208    

DOI:10.1002/prop.2190450802

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe continue the study of symmetries in the Lagrangian formalism of arbitrary order with the help of the generalized Helmholtz equations (sometimes called the Anderson‐Duchamp‐Krupka equations). For the case of second‐order equations and arbitrary vector fields we are able to establish a polynomial structure in the second‐order derivatives. This structure is based on the some linear combinations of Olver hyper‐Jacobians. We use as the main tools Fock space techniques and induction. This structure can be used to analyze Lagrangian systems with groups of Noetherian symmetries. As an illustration we analyze the case of Lagrangian equations with Abelian gauge i

ISSN:0015-8208    

DOI:10.1002/prop.2190450803

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0015-8208    

DOI:10.1002/prop.2190450801

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY