Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV

J. Adam; D. Adamova; M.M. Aggarwal; G.A. Rinella; Maria Agnello; N. Agrawal; Z. Ahammed; Shamim Ahmad; S. U. Ahn; S. Aiola; Ian Bearden; Hans Bøggild; Christian Holm Christensen; Kristjan Herlache Gulbrandsen; Jens Jørgen Gaardhøje; Hans Hjersing Dalsgaard; Børge Svane Nielsen; Alexander Colliander Hansen; Ante Bilandzic; Marek Chojnacki; Valentina Zaccolo; You Zhou; Christian Alexander Bourjau

doi:10.1016/j.physletb.2016.10.048

Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV

J. Adam, D. Adamova, M.M. Aggarwal, G.A. Rinella, Maria Agnello, N. Agrawal, Z. Ahammed, Shamim Ahmad, S. U. Ahn, S. Aiola, Ian Bearden, Hans Bøggild, Christian Holm Christensen, Kristjan Herlache Gulbrandsen, Jens Jørgen Gaardhøje, Hans Hjersing Dalsgaard, Børge Svane Nielsen, Alexander Colliander Hansen, Ante Bilandzic, Marek ChojnackiValentina Zaccolo, You Zhou, Christian Alexander Bourjau

Experimental Particle Physics

19 Citations (Scopus)

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Abstract

We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>p_T ^trig>16 GeV/c and associated charged particles of 0.5>p_T ^assoc>10 GeV/c versus the azimuthal angle difference Δφ at midrapidity in pp and central Pb–Pb collisions at s_NN=2.76 TeV with ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3 GeV/c. After subtracting the contributions of the flow background, v₂ to v₅, the per-trigger yields are extracted for |Δφ|>0.7 on the near and for |Δφ−π|>1.1 on the away side. The ratio of per-trigger yields in Pb–Pb to those in pp collisions, I_AA, is measured on the near and away side for the 0–10% most central Pb–Pb collisions. On the away side, the per-trigger yields in Pb–Pb are strongly suppressed to the level of I_AA≈0.6 for p_T ^assoc<3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low p_T ^assoc. On the near side, an enhancement of I_AA between 1.2 at the highest to 1.8 at the lowest p_T ^assoc is observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high p_T ^assoc. Only AMPT captures the enhancement at low p_T ^assoc, both on the near and away side. However, it also underpredicts I_AA above 5 GeV/c, in particular on the near-side.

Original language	English
Journal	Physics Letters B
Volume	763
Pages (from-to)	238-250
ISSN	0370-2693
DOIs	https://doi.org/10.1016/j.physletb.2016.10.048
Publication status	Published - 10 Dec 2016

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Adam, J., Adamova, D., Aggarwal, M. M., Rinella, G. A., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., U. Ahn, S., Aiola, S., Bearden, I., Bøggild, H., Christensen, C. H., Gulbrandsen, K. H., Gaardhøje, J. J., Dalsgaard, H. H., Nielsen, B. S., Hansen, A. C., Bilandzic, A., ... Bourjau, C. A. (2016). Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV. Physics Letters B, 763, 238-250. https://doi.org/10.1016/j.physletb.2016.10.048

Adam, J, Adamova, D, Aggarwal, MM, Rinella, GA, Agnello, M, Agrawal, N, Ahammed, Z, Ahmad, S, U. Ahn, S, Aiola, S, Bearden, I , Bøggild, H , Christensen, CH , Gulbrandsen, KH , Gaardhøje, JJ, Dalsgaard, HH, Nielsen, BS, Hansen, AC, Bilandzic, A, Chojnacki, M, Zaccolo, V, Zhou, Y & Bourjau, CA 2016, 'Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV', Physics Letters B, vol. 763, pp. 238-250. https://doi.org/10.1016/j.physletb.2016.10.048

@article{e2472d7440fe4e1d923138061b2e08bf,

title = "Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV",

abstract = "We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>pT trig>16 GeV/c and associated charged particles of 0.5>pT assoc>10 GeV/c versus the azimuthal angle difference Δφ at midrapidity in pp and central Pb–Pb collisions at sNN=2.76 TeV with ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3 GeV/c. After subtracting the contributions of the flow background, v2 to v5, the per-trigger yields are extracted for |Δφ|>0.7 on the near and for |Δφ−π|>1.1 on the away side. The ratio of per-trigger yields in Pb–Pb to those in pp collisions, IAA, is measured on the near and away side for the 0–10% most central Pb–Pb collisions. On the away side, the per-trigger yields in Pb–Pb are strongly suppressed to the level of IAA≈0.6 for pT assoc<3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low pT assoc. On the near side, an enhancement of IAA between 1.2 at the highest to 1.8 at the lowest pT assoc is observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high pT assoc. Only AMPT captures the enhancement at low pT assoc, both on the near and away side. However, it also underpredicts IAA above 5 GeV/c, in particular on the near-side.",

author = "J. Adam and D. Adamova and M.M. Aggarwal and G.A. Rinella and Maria Agnello and N. Agrawal and Z. Ahammed and Shamim Ahmad and {U. Ahn}, S. and S. Aiola and Ian Bearden and Hans B{\o}ggild and Christensen, {Christian Holm} and Gulbrandsen, {Kristjan Herlache} and Gaardh{\o}je, {Jens J{\o}rgen} and Dalsgaard, {Hans Hjersing} and Nielsen, {B{\o}rge Svane} and Hansen, {Alexander Colliander} and Ante Bilandzic and Marek Chojnacki and Valentina Zaccolo and You Zhou and Bourjau, {Christian Alexander}",

year = "2016",

month = dec,

day = "10",

doi = "10.1016/j.physletb.2016.10.048",

language = "English",

volume = "763",

pages = "238--250",

journal = "Physics Letters B",

issn = "0370-2693",

publisher = "Elsevier",

}

TY - JOUR

T1 - Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV

AU - Adam, J.

AU - Adamova, D.

AU - Aggarwal, M.M.

AU - Rinella, G.A.

AU - Agnello, Maria

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahmad, Shamim

AU - U. Ahn, S.

AU - Aiola, S.

AU - Bearden, Ian

AU - Bøggild, Hans

AU - Christensen, Christian Holm

AU - Gulbrandsen, Kristjan Herlache

AU - Gaardhøje, Jens Jørgen

AU - Dalsgaard, Hans Hjersing

AU - Nielsen, Børge Svane

AU - Hansen, Alexander Colliander

AU - Bilandzic, Ante

AU - Chojnacki, Marek

AU - Zaccolo, Valentina

AU - Zhou, You

AU - Bourjau, Christian Alexander

PY - 2016/12/10

Y1 - 2016/12/10

N2 - We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>pT trig>16 GeV/c and associated charged particles of 0.5>pT assoc>10 GeV/c versus the azimuthal angle difference Δφ at midrapidity in pp and central Pb–Pb collisions at sNN=2.76 TeV with ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3 GeV/c. After subtracting the contributions of the flow background, v2 to v5, the per-trigger yields are extracted for |Δφ|>0.7 on the near and for |Δφ−π|>1.1 on the away side. The ratio of per-trigger yields in Pb–Pb to those in pp collisions, IAA, is measured on the near and away side for the 0–10% most central Pb–Pb collisions. On the away side, the per-trigger yields in Pb–Pb are strongly suppressed to the level of IAA≈0.6 for pT assoc<3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low pT assoc. On the near side, an enhancement of IAA between 1.2 at the highest to 1.8 at the lowest pT assoc is observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high pT assoc. Only AMPT captures the enhancement at low pT assoc, both on the near and away side. However, it also underpredicts IAA above 5 GeV/c, in particular on the near-side.

AB - We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>pT trig>16 GeV/c and associated charged particles of 0.5>pT assoc>10 GeV/c versus the azimuthal angle difference Δφ at midrapidity in pp and central Pb–Pb collisions at sNN=2.76 TeV with ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3 GeV/c. After subtracting the contributions of the flow background, v2 to v5, the per-trigger yields are extracted for |Δφ|>0.7 on the near and for |Δφ−π|>1.1 on the away side. The ratio of per-trigger yields in Pb–Pb to those in pp collisions, IAA, is measured on the near and away side for the 0–10% most central Pb–Pb collisions. On the away side, the per-trigger yields in Pb–Pb are strongly suppressed to the level of IAA≈0.6 for pT assoc<3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low pT assoc. On the near side, an enhancement of IAA between 1.2 at the highest to 1.8 at the lowest pT assoc is observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high pT assoc. Only AMPT captures the enhancement at low pT assoc, both on the near and away side. However, it also underpredicts IAA above 5 GeV/c, in particular on the near-side.

U2 - 10.1016/j.physletb.2016.10.048

DO - 10.1016/j.physletb.2016.10.048

M3 - Journal article

SN - 0370-2693

VL - 763

SP - 238

EP - 250

JO - Physics Letters B

JF - Physics Letters B

ER -

Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV

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