TY - JOUR
T1 - Hadronic calorimeter shower size
T2 - Challenges and opportunities for jet substructure in the superboosted regime
AU - Bressler, Shikma
AU - Flacke, Thomas
AU - Kats, Yevgeny
AU - Lee, Seung J.
AU - Perez, Gilad
N1 - Funding Information:
We thank Philip Harris, David Kosower, Shmuel Nussinov and Gavin Salam for useful discussions. We also thank Mihailo Backovic and Yotam Soreq for comments on the draft. This research is supported in part by the I-CORE Program of the Planning and Budgeting Committee and the Israel Science Foundation (grant No. 1937/12 ). GP is supported by the BSF , IRG , ISF, and ERC-2013-CoG grant ( TOPCHARM #614794 ). SL and TF are supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government ( MEST ) (No. 2015R1A2A1A15052408 ), the Basic Science Research Program through the NRF funded by the Ministry of Education, Science and Technology (No. 2013R1A1A1062597 ) and the Korea-ERC researcher visiting program through the NRF (No. 2014K2a7B044399 and No. 2014K2a7A1044408 ).
Publisher Copyright:
© 2016 The Authors.
PY - 2016/5/10
Y1 - 2016/5/10
N2 - Hadrons have finite interaction size with dense material, a basic feature common to known forms of hadronic calorimeters (HCAL). We argue that substructure variables cannot use HCAL information to access the microscopic nature of jets much narrower than the hadronic shower size, which we call superboosted massive jets. It implies that roughly 15% of their transverse energy profile remains inaccessible due to the presence of long-lived neutral hadrons. This part of the jet substructure is also subject to order-one fluctuations. We demonstrate that the effects of the fluctuations are not reduced when a global correction to jet variables is applied. The above leads to fundamental limitations in the ability to extract intrinsic information from jets in the superboosted regime. The neutral fraction of a jet is correlated with its flavor. This leads to an interesting and possibly useful difference between superboosted W/. Z/. h/. t jets and their corresponding backgrounds. The QCD jets that form the background to the signal superboosted jets might also be qualitatively different in their substructure as their mass might lie at or below the Sudakov mass peak. Finally, we introduce a set of zero-cone longitudinal jet substructure variables and show that while they carry information that might be useful in certain situations, they are not in general sensitive to the jet substructure.
AB - Hadrons have finite interaction size with dense material, a basic feature common to known forms of hadronic calorimeters (HCAL). We argue that substructure variables cannot use HCAL information to access the microscopic nature of jets much narrower than the hadronic shower size, which we call superboosted massive jets. It implies that roughly 15% of their transverse energy profile remains inaccessible due to the presence of long-lived neutral hadrons. This part of the jet substructure is also subject to order-one fluctuations. We demonstrate that the effects of the fluctuations are not reduced when a global correction to jet variables is applied. The above leads to fundamental limitations in the ability to extract intrinsic information from jets in the superboosted regime. The neutral fraction of a jet is correlated with its flavor. This leads to an interesting and possibly useful difference between superboosted W/. Z/. h/. t jets and their corresponding backgrounds. The QCD jets that form the background to the signal superboosted jets might also be qualitatively different in their substructure as their mass might lie at or below the Sudakov mass peak. Finally, we introduce a set of zero-cone longitudinal jet substructure variables and show that while they carry information that might be useful in certain situations, they are not in general sensitive to the jet substructure.
UR - http://www.scopus.com/inward/record.url?scp=84960510456&partnerID=8YFLogxK
U2 - 10.1016/j.physletb.2016.02.068
DO - 10.1016/j.physletb.2016.02.068
M3 - Article
AN - SCOPUS:84960510456
VL - 756
SP - 137
EP - 141
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
SN - 0370-2693
ER -