Lech Mankiewicz

Broadband observations of the naked-eye gamma-ray burst GRB 080319B

Long-duration γ-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and γ-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet.

Jet handedness as a measure of quark and gluon polarization

Abstract We introduce a new concept, the handedness of a jet, which can be used to determine the polarization of a high-energy quark or gluon produced in a hard collision. The method can be tested in e + e - → 2 jets at the Z 0 peak where the polarization of the emerging quarks is known and correlation between jet handedness and parton polarization could be determined. Subsequently, this correlation could be used in other contexts to determine the parton polarization from a measurement of jet handedness. In particular, the method could be very useful for measuring quark and gluon polarization and the quark “transversity” distribution in the proton.

Hard exclusive electroproduction of pions

Abstract. We investigate the exclusive electroproduction of

NLO corrections to deeply virtual Compton scattering

\pi^+

The valence and strange-sea quark spin distributions in the nucleon from semi-inclusive deep inelastic lepton scattering

mesons from nucleons. To leading-twist, leading-order

QCD sum rule calculation of twist-3 contributions to polarized nucleon structure functions

\alpha_s

QCD sum rule calculation of twist-4 corrections to Bjorken and Ellis-Jaffe sum rules

accuracy, the corresponding production amplitude can be decomposed into pseudovector and pseudoscalar parts. Both can be expressed in terms of quark double distribution functions of the nucleon. While the pseudovector contribution is connected to ordinary polarized quark distributions, the pseudoscalar part can be related to one-pion t-channel exchange. We observe that the pseudovector part of the production amplitude is important at

IR-renormalon contribution to the longitudinal structure function FL

x_{\rm Bj} < 0.1

CCD detectors for wide field optical astronomy

. On the other hand, for

Quark orbital angular momentum from lattice QCD

0.1< x_{\rm Bj} < 0.4