Browsing by Author "Gardi, Einan"
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A Dispersive approach to Sudakov resummation.
Gardi, Einan; Grunberg, Georges (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200709)We present a general all–order formulation of Sudakov resummation in QCD in terms of dispersion integrals. We show that the Sudakov exponent can be written as a dispersion integral over spectral density functions, weighted ... 
Inclusive B decays from resummed perturbation theory.
Gardi, Einan (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200703)I review the recent progress in computing inclusive B decay widths and spectra and its implications on the interpretation of measurements from the B factories. I discuss the inclusive charmless semileptonic decay, ¯B ! ... 
Inclusive Bdecay spectra and IR renormalons.
Gardi, Einan (HEP, Cavendish Laboratory, University of Cambridge, 200407)I illustrate the role of infrared renormalons in computing inclusive Bdecay spectra. I explain the relation between the leading ambiguity in the definition of Sudakov form factor exp(N /M) and that of the pole mass, ... 
Inclusive distributions near kinematic thresholds.
Gardi, Einan (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200606)The main challenge in computing inclusive cross sections and decay spectra in QCD is posed by kinematic thresholds. The threshold region is characterized by stringent phase–space constraints that are reflected in large ... 
Inclusive spectra in charmless semileptonic B decays by dressed gluon exponentiation.
Andersen, Jeppe R.; Gardi, Einan (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200509)The triple differential spectrum in ¯B −→ Xul¯ν is computed by Dressed Gluon Exponentiation (DGE). In this framework the onshell calculation, converted into hadronic variables, can be directly used as an approximation ... 
A New approach to inclusive decay spectra.
Gardi, Einan; Andersen, Jeppe R. (HEP, Cavendish Laboratory, University of Cambridge, 200504)The main obstacle in describing inclusive decay spectra in QCD — which, in particular, limits the precision in extrapolating the measured ¯B −→ Xs rate to the full phase space as well as in extracting Vub from inclusive ... 
On the quark distribution in an onshell heavy quark and its allorder relations with the perturbative fragmentation function.
Gardi, Einan (HEP, Cavendish Laboratory, University of Cambridge, 200501)I present new results on the quark distribution in an onshell heavy quark in perturbative QCD and explore its all–order relations with heavy–quark fragmentation. I first compute the momentum distribution function to all ... 
Progress in computing inclusive B decay spectra.
Gardi, Einan; Andersen, Jeppe R. (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200601)We review the progress in the QCD calculation of inclusive decay spectra. It was recently shown that the inherent infrared finiteness of inclusive spectra extends beyond the level of logarithms. Dressed Gluon Exponentia ... 
Radiative and semileptonic B meson decay spectra: Sudakov resummation beyond logarithmic accuracy and the pole mass.
Gardi, Einan (HEP, Cavendish Laboratory, University of Cambridge, 200403)The inclusive spectra of radiative and semileptonic B–meson decays near the endpoint is computed taking into account renormalons in the Sudakov exponent (Dressed Gluon Exponentiation). In this framework we demonstrate ... 
Radiative B decay spectrum: DGE at NNLO.
Andersen, Jeppe R.; Gardi, Einan (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200609)We compute the differential ¯B → Xsγ decay width in the Standard Model as a function of the photon energy using Dressed Gluon Exponentiation (DGE). The resummed spectrum is matched with the fixed–order expansion, making ... 
Renormalon approach to higher twist distribution amplitudes and the convergence of the conformal expansion.
Braun, Vladimir; Gardi, Einan; Gottwald, Stefan (HEP, Cavendish Laboratory, University of Cambridge, 200401)Power corrections to exclusive processes are usually calculated using models for twist–four distribution amplitudes (DA) which are based on the leading–order terms in the conformal expansion. In this work we develop a ... 
Running coupling and power corrections in nonlinear evolution at the highenergy limit.
Gardi, Einan; Kuokkanen, Janne; Rummukainen, Kari; Weigert, Heribert (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200609)A main feature of highenergy scattering in QCD is saturation in the number density of gluons. This phenomenon is described by nonlinear evolution equations, JIMWLK and BK, which have been derived at leading logarithmic ... 
Runningcoupling effects in the tripledifferential charmless semileptonic decay width.
Gambino, Paolo; Gardi, Einan; Ridolfi, Giovanni (High Energy Physics, Cavendish Laboratory, University of Cambridge, 200610)We compute the fully–differential ¯B → Xul¯ν decay width to all orders in perturbation theory in the large–β0 limit. Each of the five structure functions that build the hadronic tensor is expressed as a Borel integral, ... 
Taming the antiB > X(s) gamma spectrum by dressed gluon exponentiation.
Andersen, Jeppe R.; Gardi, Einan (HEP, Cavendish Laboratory, University of Cambridge, 200502)We show that the ¯B −→ Xsγ photon energy (E ) spectrum can be reliably computed by resummed perturbation theory. Our calculation is based on Dressed Gluon Exponentiation (DGE) incorporating Sudakov and renormalon ...