Sound edge of the quenching jets

Abstract

When quenching jets deposit certain amounts of energy and momentum into ambient matter, part of it propagates in the form of shocks/sounds. The ``sound surface'', separating disturbed and undisturbed parts of the fireball, makes what we call the sound edge of jets. In this work we semianalytically study its shape, in various geometries. We further argue that since hadrons with in the kinematical range of ${p}_{\ensuremath{\perp}}\ensuremath{\sim}2\phantom{\rule{0.16em}{0ex}}\phantom{\rule{4pt}{0ex}}\mathrm{GeV}$ originate mostly from the ``rim'' of the fireball, near the maximum of the radial flow at the freeze-out surface, only the intersection of the ``sound surface'' with this ``rim'' would be observable. The resulting ``jet edge'' has a form of extra matter at the elliptic curve, in $\ensuremath{\Delta}\ensuremath{\phi},\ensuremath{\Delta}\ensuremath{\eta}$ coordinates, with radius $|\ensuremath{\Delta}\ensuremath{\phi}|\ensuremath{\sim}|\ensuremath{\Delta}\ensuremath{\eta}|\ensuremath{\sim}1$. In the case of large energy/momentum deposition $\ensuremath{\sim}100\phantom{\rule{0.16em}{0ex}}\phantom{\rule{4pt}{0ex}}\mathrm{GeV}$ we argue that the event should be considered as two subevents, with the interior of the ``sound surface'' having modified radial and directed flow. We further argue that in the kinematical range of ${p}_{\ensuremath{\perp}}\ensuremath{\sim}3\phantom{\rule{0.16em}{0ex}}\phantom{\rule{4pt}{0ex}}\mathrm{GeV}$ the effect of that can be large enough to be seen on an event-by-event basis. If so, this effect has the potential to become a valuable tool to address the geometry of jet production and quenching.