How many interactions does it take to modify a jet?

It is a continued open question how there can be an azimuthal anisotropy of high <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi> <mml:mo>⊥</mml:mo></mml:msub> </mml:math> particles quantified by a sizable <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:math> in p+Pb collisions when, at the same time, the nuclear modification factor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi> <mml:mtext>AA</mml:mtext></mml:msub> </mml:math> is consistent with unity. We address this puzzle within the framework of the jet quenching model Jewel. In the absence of reliable medium models for small collision systems we use the number of scatterings per parton times the squared Debye mass to characterise the strength of medium modifications. Working with a simple brick medium model we show that, for small systems and not too strong modifications, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi> <mml:mtext>AA</mml:mtext></mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:math> approximately scale with this quantity. We find that a comparatively large number of scatterings is needed to generate measurable jet quenching. Our results indicate that the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi> <mml:mtext>AA</mml:mtext></mml:msub> </mml:math> corresponding to the observed <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:math> could fall within the experimental uncertainty. Thus, while there is currently no contradiction with the measurements, our results indicate that <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi> <mml:mtext>AA</mml:mtext></mml:msub> </mml:math> go hand-in-hand. We also discuss departures from scaling, in particular, due to sizable inelastic energy loss.