Elsevier

Physics Letters B

Volume 789, 10 February 2019, Pages 167-190
Physics Letters B

Measurement of photon–jet transverse momentum correlations in 5.02 TeV Pb + Pb and pp collisions with ATLAS

https://doi.org/10.1016/j.physletb.2018.12.023Get rights and content
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Abstract

Jets created in association with a photon can be used as a calibrated probe to study energy loss in the medium created in nuclear collisions. Measurements of the transverse momentum balance between isolated photons and inclusive jets are presented using integrated luminosities of 0.49 nb−1 of Pb + Pb collision data at sNN=5.02 TeV and 25 pb−1 of pp collision data at s=5.02 TeV recorded with the ATLAS detector at the LHC. Photons with transverse momentum 63.1<pTγ<200 GeV and |ηγ|<2.37 are paired with all jets in the event that have pTjet>31.6 GeV and pseudorapidity |ηjet|<2.8. The transverse momentum balance given by the jet-to-photon pT ratio, xJγ, is measured for pairs with azimuthal opening angle Δϕ>7π/8. Distributions of the per-photon jet yield as a function of xJγ, (1/Nγ)(dN/dxJγ), are corrected for detector effects via a two-dimensional unfolding procedure and reported at the particle level. In pp collisions, the distributions are well described by Monte Carlo event generators. In Pb + Pb collisions, the xJγ distribution is modified from that observed in pp collisions with increasing centrality, consistent with the picture of parton energy loss in the hot nuclear medium. The data are compared with a suite of energy-loss models and calculations.

Cited by (0)

a

Also at Borough of Manhattan Community College, City University of New York, NY, United States of America.

b

Also at Centre for High Performance Computing, CSIR Campus, Rosebank, Cape Town, South Africa.

c

Also at CERN, Geneva, Switzerland.

d

Also at CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France.

e

Also at Département de Physique Nucléaire et Corpusculaire, Université de Genève, Genève, Switzerland.

f

Also at Departament de Fisica de la Universitat Autonoma de Barcelona, Barcelona, Spain.

g

Also at Departamento de Física Teorica y del Cosmos, Universidad de Granada, Granada (Spain), Spain.

h

Also at Department of Applied Physics and Astronomy, University of Sharjah, Sharjah, United Arab Emirates.

i

Also at Department of Financial and Management Engineering, University of the Aegean, Chios, Greece.

j

Also at Department of Physics and Astronomy, University of Louisville, Louisville, KY, United States of America.

k

Also at Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom.

l

Also at Department of Physics, California State University, Fresno, CA, United States of America.

m

Also at Department of Physics, California State University, Sacramento, CA, United States of America.

n

Also at Department of Physics, King's College London, London, United Kingdom.

o

Also at Department of Physics, St. Petersburg State Polytechnical University, St. Petersburg, Russia.

p

Also at Department of Physics, University of Fribourg, Fribourg, Switzerland.

q

Also at Department of Physics, University of Michigan, Ann Arbor, MI, United States of America.

r

Also at Dipartimento di Fisica E. Fermi, Università di Pisa, Pisa, Italy.

s

Also at Giresun University, Faculty of Engineering, Giresun, Turkey.

t

Also at Graduate School of Science, Osaka University, Osaka, Japan.

u

Also at Hellenic Open University, Patras, Greece.

v

Also at Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania.

w

Also at II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany.

x

Also at Institucio Catalana de Recerca i Estudis Avancats, ICREA, Barcelona, Spain.

y

Also at Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany.

z

Also at Institute for Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen/Nikhef, Nijmegen, Netherlands.

aa

Also at Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, Budapest, Hungary.

ab

Also at Institute of Particle Physics (IPP), Canada.

ac

Also at Institute of Physics, Academia Sinica, Taipei, Taiwan.

ad

Also at Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan.

ae

Also at Institute of Theoretical Physics, Ilia State University, Tbilisi, Georgia.

af

Also at LAL, Université Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, Orsay, France.

ag

Also at Louisiana Tech University, Ruston, LA, United States of America.

ah

Also at Manhattan College, New York, NY, United States of America.

ai

Also at Moscow Institute of Physics and Technology State University, Dolgoprudny, Russia.

aj

Also at National Research Nuclear University MEPhI, Moscow, Russia.

ak

Also at Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.

al

Also at School of Physics, Sun Yat-sen University, Guangzhou, China.

am

Also at The City College of New York, New York, NY, United States of America.

an

Also at The Collaborative Innovation Center of Quantum Matter (CICQM), Beijing, China.

ao

Also at Tomsk State University, Tomsk, and Moscow Institute of Physics and Technology State University, Dolgoprudny, Russia.

ap

Also at TRIUMF, Vancouver, BC, Canada.

aq

Also at Universita di Napoli Parthenope, Napoli, Italy.

Deceased.

E-mail address: [email protected].