Jet evolution from weak to strong coupling

Abstract

Recent studies, using the AdS/CFT correspondence, of the radiation produced by a decaying system or by an accelerated charge in the N=4 supersymmetric Yang-Mills theory, led to a striking result: the 'supergravity backreaction', which is supposed to describe the energy density at infinitely strong coupling, yields exactly the same result as at zero coupling, that is, it shows no trace of quantum broadening. We argue that this is not a real property of the radiation at strong coupling, but an artifact of the backreaction calculation, which is unable to faithfully capture the space-time distribution of the radiation. This becomes obvious in the case of a decaying system ('virtual photon'), for which the backreaction is tantamount to computing a three-point function in the conformal gauge theory, which is independent of the coupling since protected by symmetries. Whereas this non-renormalization property is specific to the conformal N=4 SYM theory, we argue that the failure of the three-point function to provide a local measurement is in fact generic: it holds in any field theory with non-trivial interactions. To properly study a localized distribution, one should rather compute a four-point function, as standard in deep inelastic scattering. We substantiate these considerations with studies of the radiation produced by the decay of a time-like photon at both weak and strong coupling. We show that by computing four-point functions, in perturbation theory at weak coupling and, respectively, from Witten diagrams at strong coupling, one can follow the quantum evolution and thus demonstrate the broadening of the energy distribution. This broadening is slow when the coupling is weak but it proceeds as fast as possible in the limit of a strong coupling.

49 pages, 6 figures

References in corpus (16)

• Energy loss of a heavy quark moving through N=4 supersymmetric Yang-Mills plasma
• Conformal collider physics: Energy and charge correlations
• Calculating the Jet Quenching Parameter from AdS/CFT
• The Pomeron and Gauge/String Duality
• Photon and dilepton production in supersymmetric Yang-Mills plasma
• Gluon energy loss in the gauge-string duality
• The wake of a quark moving through a strongly-coupled $\mathcal{N}=4$ supersymmetric Yang-Mills plasma
• Comparing energy loss and $p_{\perp }$-broadening in perturbative QCD with strong coupling $\mathcal{N}=4$ SYM theory
• Deep inelastic scattering off a N=4 SYM plasma at strong coupling
• Energy disturbances due to a moving quark from gauge-string duality
• Deep inelastic scattering from gauge string duality in the soft wall model
• Aspects of the UV/IR correspondence : energy broadening and string fluctuations
• Energy loss in a strongly coupled anisotropic plasma
• Jet fragmentation and gauge/string duality
• Thermal hadron spectrum in $e^{+}{e}^{-}$ annihilation from gauge/string duality
• Holographic dual of collimated radiation

Cited by in corpus (4)

• Radiation and a dynamical UV/IR connection in AdS/CFT
• Generalizing event shapes: In search of lost collider time
• No Line on the Horizon: On Uniform Acceleration and Gluonic Fields at Strong Coupling
• Energy Correlators Beyond Angles