Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV

S. Acharya; F Acosta; D. Adamova; A. Alder; J Adolfsson; MM. Aggarwal; G.A. Rinella; Maria Agnello; N. Agrawal; Z. Ahammed; S.U. Ahn; S. Aiola; A. Akindinov; M. Al-Turany; SN Alam; DSD Albuquerque; D. Aleksandrov; B Alessandro; R. Alfaro Molina; Yusuf Ali; A. Alici; A. Alkin; J. Alme; T. Alt; Ian Bearden; Christian Alexander Bourjau; Ante Bilandzic; Jens Jørgen Gaardhøje; Katarina Gajdosova; bsm989 bsm989; Freja Thoresen; Lais Ozelin De Lima Pimentel; Børge Svane Nielsen; Marek Chojnacki; You Zhou; Christian Holm Christensen; Vytautas Vislavicius

doi:10.1007/JHEP10(2018)139

Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV

S. Acharya, F Acosta, D. Adamova, A. Alder, J Adolfsson, MM. Aggarwal, G.A. Rinella, Maria Agnello, N. Agrawal, Z. Ahammed, S.U. Ahn, S. Aiola, A. Akindinov, M. Al-Turany, SN Alam, DSD Albuquerque, D. Aleksandrov, B Alessandro, R. Alfaro Molina, Yusuf AliA. Alici, A. Alkin, J. Alme, T. Alt, Ian Bearden, Christian Alexander Bourjau, Ante Bilandzic, Jens Jørgen Gaardhøje, Katarina Gajdosova, bsm989 bsm989, Freja Thoresen, Lais Ozelin De Lima Pimentel, Børge Svane Nielsen, Marek Chojnacki, You Zhou, Christian Holm Christensen, Vytautas Vislavicius

Experimental Particle Physics

18 Citations (Scopus)

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Abstract

We present the measurement of a new set of jet shape observables for track-based jets in central Pb-Pb collisions at sNN=2.76 TeV. The set of jet shapes includes the first radial moment or angularity, g; the momentum dispersion, p_TD; and the difference between the leading and sub-leading constituent track transverse momentum, LeSub. These observables provide complementary information on the jet fragmentation and can constrain different aspects of the theoretical description of jet-medium interactions. The jet shapes were measured for a small resolution parameter R = 0.2 and were fully corrected to particle level. The observed jet shape modifications indicate that in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by PYTHIA calculations, which were validated with the measurements of the jet shapes in proton-proton collisions at s=7 TeV. The comparison of the measured distributions to templates for quark and gluon-initiated jets indicates that in-medium fragmentation resembles that of quark jets in vacuum. We further argue that the observed modifications are not consistent with a totally coherent energy loss picture where the jet loses energy as a single colour charge, suggesting that the medium resolves the jet structure at the angular scales probed by our measurements (R = 0.2). Furthermore, we observe that small-R jets can help to isolate purely energy loss effects from other effects that contribute to the modifications of the jet shower in medium such as the correlated background or medium response.[Figure not available: see fulltext.].

Original language	English
Article number	139
Journal	The Journal of High Energy Physics
Volume	2018
Issue number	10
Number of pages	29
ISSN	1126-6708
DOIs	https://doi.org/10.1007/JHEP10(2018)139
Publication status	Published - 1 Oct 2018

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Acharya, S., Acosta, F., Adamova, D., Alder, A., Adolfsson, J., Aggarwal, MM., Rinella, G. A., Agnello, M., Agrawal, N., Ahammed, Z., Ahn, S. U., Aiola, S., Akindinov, A., Al-Turany, M., Alam, SN., Albuquerque, DSD., Aleksandrov, D., Alessandro, B., Alfaro Molina, R., ... Vislavicius, V. (2018). Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV. The Journal of High Energy Physics, 2018(10), Article 139. https://doi.org/10.1007/JHEP10(2018)139

Acharya, S, Acosta, F, Adamova, D, Alder, A, Adolfsson, J, Aggarwal, MM, Rinella, GA, Agnello, M, Agrawal, N, Ahammed, Z, Ahn, SU, Aiola, S, Akindinov, A, Al-Turany, M, Alam, SN, Albuquerque, DSD, Aleksandrov, D, Alessandro, B, Alfaro Molina, R, Ali, Y, Alici, A, Alkin, A, Alme, J, Alt, T, Bearden, I, Bourjau, CA, Bilandzic, A, Gaardhøje, JJ, Gajdosova, K, bsm989, B, Thoresen, F, Ozelin De Lima Pimentel, L, Nielsen, BS, Chojnacki, M, Zhou, Y , Christensen, CH & Vislavicius, V 2018, 'Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV', The Journal of High Energy Physics, vol. 2018, no. 10, 139. https://doi.org/10.1007/JHEP10(2018)139

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title = "Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV",

abstract = "We present the measurement of a new set of jet shape observables for track-based jets in central Pb-Pb collisions at sNN=2.76 TeV. The set of jet shapes includes the first radial moment or angularity, g; the momentum dispersion, pTD; and the difference between the leading and sub-leading constituent track transverse momentum, LeSub. These observables provide complementary information on the jet fragmentation and can constrain different aspects of the theoretical description of jet-medium interactions. The jet shapes were measured for a small resolution parameter R = 0.2 and were fully corrected to particle level. The observed jet shape modifications indicate that in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by PYTHIA calculations, which were validated with the measurements of the jet shapes in proton-proton collisions at s=7 TeV. The comparison of the measured distributions to templates for quark and gluon-initiated jets indicates that in-medium fragmentation resembles that of quark jets in vacuum. We further argue that the observed modifications are not consistent with a totally coherent energy loss picture where the jet loses energy as a single colour charge, suggesting that the medium resolves the jet structure at the angular scales probed by our measurements (R = 0.2). Furthermore, we observe that small-R jets can help to isolate purely energy loss effects from other effects that contribute to the modifications of the jet shower in medium such as the correlated background or medium response.[Figure not available: see fulltext.].",

author = "S. Acharya and F Acosta and D. Adamova and A. Alder and J Adolfsson and MM. Aggarwal and G.A. Rinella and Maria Agnello and N. Agrawal and Z. Ahammed and S.U. Ahn and S. Aiola and A. Akindinov and M. Al-Turany and SN Alam and DSD Albuquerque and D. Aleksandrov and B Alessandro and {Alfaro Molina}, R. and Yusuf Ali and A. Alici and A. Alkin and J. Alme and T. Alt and Ian Bearden and Bourjau, {Christian Alexander} and Ante Bilandzic and Gaardh{\o}je, {Jens J{\o}rgen} and Katarina Gajdosova and bsm989 bsm989 and Freja Thoresen and {Ozelin De Lima Pimentel}, Lais and Nielsen, {B{\o}rge Svane} and Marek Chojnacki and You Zhou and Christensen, {Christian Holm} and Vytautas Vislavicius",

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doi = "10.1007/JHEP10(2018)139",

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T1 - Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV

AU - Acharya, S.

AU - Acosta, F

AU - Adamova, D.

AU - Alder, A.

AU - Adolfsson, J

AU - Aggarwal, MM.

AU - Rinella, G.A.

AU - Agnello, Maria

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahn, S.U.

AU - Aiola, S.

AU - Akindinov, A.

AU - Al-Turany, M.

AU - Alam, SN

AU - Albuquerque, DSD

AU - Aleksandrov, D.

AU - Alessandro, B

AU - Alfaro Molina, R.

AU - Ali, Yusuf

AU - Alici, A.

AU - Alkin, A.

AU - Alme, J.

AU - Alt, T.

AU - Bearden, Ian

AU - Bourjau, Christian Alexander

AU - Bilandzic, Ante

AU - Gaardhøje, Jens Jørgen

AU - Gajdosova, Katarina

AU - bsm989, bsm989

AU - Thoresen, Freja

AU - Ozelin De Lima Pimentel, Lais

AU - Nielsen, Børge Svane

AU - Chojnacki, Marek

AU - Zhou, You

AU - Christensen, Christian Holm

AU - Vislavicius, Vytautas

PY - 2018/10/1

Y1 - 2018/10/1

N2 - We present the measurement of a new set of jet shape observables for track-based jets in central Pb-Pb collisions at sNN=2.76 TeV. The set of jet shapes includes the first radial moment or angularity, g; the momentum dispersion, pTD; and the difference between the leading and sub-leading constituent track transverse momentum, LeSub. These observables provide complementary information on the jet fragmentation and can constrain different aspects of the theoretical description of jet-medium interactions. The jet shapes were measured for a small resolution parameter R = 0.2 and were fully corrected to particle level. The observed jet shape modifications indicate that in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by PYTHIA calculations, which were validated with the measurements of the jet shapes in proton-proton collisions at s=7 TeV. The comparison of the measured distributions to templates for quark and gluon-initiated jets indicates that in-medium fragmentation resembles that of quark jets in vacuum. We further argue that the observed modifications are not consistent with a totally coherent energy loss picture where the jet loses energy as a single colour charge, suggesting that the medium resolves the jet structure at the angular scales probed by our measurements (R = 0.2). Furthermore, we observe that small-R jets can help to isolate purely energy loss effects from other effects that contribute to the modifications of the jet shower in medium such as the correlated background or medium response.[Figure not available: see fulltext.].

AB - We present the measurement of a new set of jet shape observables for track-based jets in central Pb-Pb collisions at sNN=2.76 TeV. The set of jet shapes includes the first radial moment or angularity, g; the momentum dispersion, pTD; and the difference between the leading and sub-leading constituent track transverse momentum, LeSub. These observables provide complementary information on the jet fragmentation and can constrain different aspects of the theoretical description of jet-medium interactions. The jet shapes were measured for a small resolution parameter R = 0.2 and were fully corrected to particle level. The observed jet shape modifications indicate that in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by PYTHIA calculations, which were validated with the measurements of the jet shapes in proton-proton collisions at s=7 TeV. The comparison of the measured distributions to templates for quark and gluon-initiated jets indicates that in-medium fragmentation resembles that of quark jets in vacuum. We further argue that the observed modifications are not consistent with a totally coherent energy loss picture where the jet loses energy as a single colour charge, suggesting that the medium resolves the jet structure at the angular scales probed by our measurements (R = 0.2). Furthermore, we observe that small-R jets can help to isolate purely energy loss effects from other effects that contribute to the modifications of the jet shower in medium such as the correlated background or medium response.[Figure not available: see fulltext.].

U2 - 10.1007/JHEP10(2018)139

DO - 10.1007/JHEP10(2018)139

M3 - Journal article

SN - 1126-6708

VL - 2018

JO - The Journal of High Energy Physics

JF - The Journal of High Energy Physics

IS - 10

M1 - 139

ER -

Medium modification of the shape of small-radius jets in central Pb-Pb collisions at root s(NN)=2:76 TeV

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