The jet cross section and jet-substructure observables in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mo>+</mo><mi>p</mi></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>k</mi><mi>t</mi></msub></math> algorithm with a jet radius of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo>=</mo><mn>0.3</mn></math> for jets with transverse momentum within <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>8.0</mn><mo>&lt;</mo><msub><mi>p</mi><mi>T</mi></msub><mo>&lt;</mo><mn>40.0</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><mi>c</mi></math> and pseudorapidity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><mi>η</mi><mo stretchy="false">|</mo><mo>&lt;</mo><mn>0.15</mn></math>. Measurements include the jet cross section, as well as distributions of SoftDrop-groomed momentum fraction (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>z</mi><mi>g</mi></msub></math>), charged-particle transverse momentum with respect to jet axis (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>j</mi><mi>T</mi></msub></math>), and radial distributions of charged particles within jets (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi></math>). Also measured was the distribution of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ξ</mi><mo>=</mo><mo>−</mo><mi>ln</mi><mo stretchy="false">(</mo><mi>z</mi><mo stretchy="false">)</mo></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math> is the fraction of the jet momentum carried by the charged particle. The measurements are compared to theoretical next-to and next-to-next-to-leading-order calculations, the pythia and herwig event generators, and to other existing experimental results. Indicated from these measurements is a lower particle multiplicity in jets at RHIC energies when compared to models. Also noted are implications for future jet measurements with sPHENIX at RHIC as well as at the future Electron-Ion Collider.

Hungary

N.J. Abdulameer

United States

U. Acharya

C. Aidala

N.N. Ajitanand

Japan

Y. Akiba

R. Akimoto

J. Alexander

M. Alfred

V. Andrieux

Russia

S. Antsupov

K. Aoki

N. Apadula

H. Asano

E.T. Atomssa

T.C. Awes

B. Azmoun

V. Babintsev

M. Bai

China

X. Bai

N.S. Bandara

B. Bannier

E. Bannikov

K.N. Barish

S. Bathe

V. Baublis

C. Baumann

S. Baumgart

A. Bazilevsky

M. Beaumier

R. Belmont

A. Berdnikov

Y. Berdnikov

L. Bichon

D. Black

B. Blankenship

D.S. Blau

J.S. Bok

V. Borisov

K. Boyle

M.L. Brooks

J. Bryslawskyj

H. Buesching

V. Bumazhnov

S. Butsyk

S. Campbell

R. Cervantes

C.H. Chen

D. Chen

M. Chiu

C.Y. Chi

I.J. Choi

South Korea

J.B. Choi

S. Choi

Sweden

P. Christiansen

T. Chujo

V. Cianciolo

Israel

Z. Citron

B.A. Cole

M. Connors

R. Corliss

N. Cronin

N. Crossette

M. Csanád

T. Csörgő

L. D’Orazio

T.W. Danley

A. Datta

M.S. Daugherity

G. David

K. DeBlasio

K. Dehmelt

A. Denisov

A. Deshpande

E.J. Desmond

L. Ding

A. Dion

D. Dixit

V. Doomra

J.H. Do

France

O. Drapier

A. Drees

K.A. Drees

J.M. Durham

A. Durum

H. En’yo

T. Engelmore

A. Enokizono

R. Esha

K.O. Eyser

B. Fadem

W. Fan

N. Feege

D.E. Fields

Czechia

M. Finger

D. Firak

D. Fitzgerald

F. Fleuret

S.L. Fokin

J.E. Frantz

Measurement of inclusive jet cross section and substructure in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mo>+</mo><mi>p</mi></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>

In this work, we present the transverse momentum spectra of prompt and decay photons in Au-Au collisions for <math altimg='si1.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo></math> 200 GeV, 62.4 GeV, 39 GeV, and 27 GeV. The major sources of the photons in Angantyr include hard processes, Parton showers, and resonance decay. The multiparton interactions and hadronic rescatterings significantly increase the photon yield. The model shows a good match with the available experimental data at high <math altimg='si2.svg'><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>. The difference in yield at low <math altimg='si2.svg'><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> suggests that Quark Gluon Plasma of <math altimg='si3.svg'><msub><mrow><mi>T</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math> = 0.167 GeV/c in central Au-Au collision at 200 GeV is formed, the new effective temperature is less than the ones extracted without removing background photons. At low <math altimg='si2.svg'><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> the decay photon spectra scales with <math altimg='si4.svg'><msup><mrow><mo stretchy='false'>(</mo><mfrac><mrow><mi>d</mi><msub><mrow><mi>N</mi></mrow><mrow><mi>c</mi><mi>h</mi></mrow></msub></mrow><mrow><mi>d</mi><mi>&#951;</mi></mrow></mfrac><mo stretchy='false'>)</mo></mrow><mrow><mn>1.25</mn></mrow></msup></math>, the scaling is independent of collision energy and system size. The scaling no longer holds at high <math altimg='si2.svg'><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> and the spectra become beam energy dependent. The scaled <math altimg='si2.svg'><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> spectra of p-p and d-Au collisions show an opposite trend at high <math altimg='si2.svg'><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>, their scaled yield is greater than the Au-Au collision at the same energy.

India

Satya Ranjan Nayak

Gauri Devi

B.K. Singh

A background for thermal photons in heavy ion collisions

In this letter, we present the study of the role of octupole deformation in non-spherical nuclei in most-central Pb-Pb collisions at LHC energy regime. The sensitivity of octupole deformation <math><msub><mrow><mi>β</mi></mrow><mrow><mn>3</mn></mrow></msub></math> to the QGP observables is presented by employing Monte-Carlo HYDJET++ model. Motivated by the discrepancies in the <math><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub></math>-to-<math><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub></math> puzzle found in Pb-Pb collisions and the low-energy nuclear structure calculations of nuclear deformation, we studied the first basic observables necessary for any study in heavy-ion collisions. Using HYDJET++ framework, we calculate the pseudorapidity distribution, transverse momentum (<math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>) spectra and average anisotropic flow (<math><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub></math> and <math><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub></math>) of primary charged hadrons with different parameters in two geometrical configurations: body-body and tip-tip type of Pb-Pb collisions. The kinematic ranges <math><mn>0</mn><mo>&lt;</mo><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>&lt;</mo><mn>20</mn></math> GeV/c and <math><mo>|</mo><mi>η</mi><mo>|</mo><mo>&lt;</mo><mn>0.8</mn></math> are considered. We observe that the charged hadron multiplicity and transverse momentum spectra are dependent on the strength of octupole deformation parameter. <math><mo>〈</mo><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>〉</mo></math> and <math><mo>〈</mo><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>〉</mo></math> in body-body collisions show weak positive correlation with <math><msub><mrow><mi>β</mi></mrow><mrow><mn>3</mn></mrow></msub></math> while average anisotropic flow in tip-tip collisions are weakly correlated to <math><msub><mrow><mi>β</mi></mrow><mrow><mn>3</mn></mrow></msub></math> in most-central collision region.

Saraswati Pandey

Study of octupole deformations in Pb-Pb collisions at 5.02 TeV

There is strong evidence for the formation of small droplets of quark-gluon plasma in <math><mrow><mi>p</mi><mo>/</mo><mi>d</mi><mo>/</mo><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>+</mo><mi>Au</mi></mrow></math> collisions at the Relativistic Heavy Ion Collider (RHIC) and in <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi><mo>/</mo><mi>Pb</mi></mrow></math> collisions at the Large Hadron Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proved insightful. In the present analysis, we find excellent agreement with the previously published PHENIX at RHIC results on elliptical and triangular flow with an independent analysis via the two-particle correlation method, which has quite different systematic uncertainties and an independent code base. In addition, the results are extended to other detector combinations with different kinematic (pseudorapidity) coverage. These results provide additional constraints on contributions from nonflow and longitudinal decorrelations.

U.A. Acharya

A. Adare

C. Ayuso

S. Beckman

M. Boer

C. Butler

V. Canoa Roman

L.D. Liu

P.B. Diss

M. Dumancic

T. Elder

H. En'yo

S. Esumi

A. Franz

A.D. Frawley

Y. Fukuda

P. Gallus

C. Gal

P. Garg

H. Ge

M. Giles

F. Giordano

A. Glenn

Y. Goto

N. Grau

S.V. Greene

M. Grosse Perdekamp

T. Gunji

H. Guragain

T. Hachiya

Kinematic dependence of azimuthal anisotropies in <math><mrow><mi>p</mi><mo>+</mo><mi>Au</mi><mo>,</mo></mrow></math> <math><mrow><mi>d</mi><mo>+</mo><mi>Au</mi><mo>,</mo></mrow></math> and <math><mrow><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>+</mo><mi>Au</mi></mrow></math> at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>200</mn><mspace width="4pt"></mspace><mi>GeV</mi></mrow></math>

The PHENIX experiment at the Relativistic Heavy Ion Collider measured <math><msup><mi>π</mi><mn>0</mn></msup></math> and <math><mi>η</mi></math> mesons at midrapidity in <math><mrow><mi>U</mi><mo>+</mo><mi>U</mi></mrow></math> collisions at <math><mrow><msqrt><msub><mi>s</mi><msub><mrow></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msub></msqrt><mo>=</mo><mn>192</mn></mrow></math> GeV in a wide transverse momentum range. Measurements were performed in the <math><mrow><msup><mi>π</mi><mn>0</mn></msup><mrow><mo>(</mo><mi>η</mi><mo>)</mo></mrow><mo>→</mo><mi>γ</mi><mi>γ</mi></mrow></math> decay modes. A strong suppression of <math><msup><mi>π</mi><mn>0</mn></msup></math> and <math><mi>η</mi></math> meson production at high transverse momentum was observed in central <math><mrow><mi>U</mi><mo>+</mo><mi>U</mi></mrow></math> collisions relative to binary scaled <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math> results. Yields of <math><msup><mi>π</mi><mn>0</mn></msup></math> and <math><mi>η</mi></math> mesons measured in <math><mrow><mi>U</mi><mo>+</mo><mi>U</mi></mrow></math> collisions show similar suppression pattern to those measured in <math><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions at <math><mrow><msqrt><msub><mi>s</mi><msub><mrow></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msub></msqrt><mo>=</mo><mn>200</mn></mrow></math> GeV for similar numbers of participant nucleons. The <math><mrow><mi>η</mi><mo>/</mo><msup><mi>π</mi><mn>0</mn></msup></mrow></math> ratios do not show dependence on centrality or transverse momentum and are consistent with previously measured values in hadron-hadron, hadron-nucleus, nucleus-nucleus, and <math><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></mrow></math> collisions.

L. D'Orazio

Y. Fukao

T. Fusayasu

K. Gainey

A. Garishvili

I. Garishvili

X. Gong

M. Gonin

Production of <math><msup><mi>π</mi><mn>0</mn></msup></math> and <math><mi>η</mi></math> mesons in U+U collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>192</mn></mrow></math> GeV

We present direct photon-hadron correlations in 200 GeV/<math><mi>A</mi></math> <math><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math>, <math><mrow><mi>d</mi><mo>+</mo><mi>Au</mi></mrow></math>, and <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math> collisions, for direct photon <math><msub><mi>p</mi><mi>T</mi></msub></math> from 5–12 <math><mrow><mi>GeV</mi><mo>/</mo><mi>c</mi></mrow></math>, collected by the PHENIX Collaboration in the years from 2006 to 2011. We observe no significant modification of jet fragmentation in <math><mrow><mi>d</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions, indicating that cold nuclear matter effects are small or absent. Hadrons carrying a large fraction of the quark's momentum are suppressed in <math><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> compared to <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math> and <math><mrow><mi>d</mi><mo>+</mo><mi>Au</mi></mrow></math>. As the momentum fraction decreases, the yield of hadrons in <math><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> increases to an excess over the yield in <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math> collisions. The excess is at large angles and at low hadron <math><msub><mi>p</mi><mi>T</mi></msub></math> and is most pronounced for hadrons associated with lower momentum direct photons. Comparison to theoretical calculations suggests that the hadron excess arises from medium response to energy deposited by jets.

JINR

S. Afanasiev

H. Al-Bataineh

H. Al-Ta'ani

A. Angerami

Y. Aramaki

E.C. Aschenauer

R. Averbeck

G. Baksay

L. Baksay

B. Bassalleck

A.T. Basye

Germany

S. Belikov

R. Bennett

J.H. Bhom

A.A. Bickley

G. Bunce

C.M. Camacho

A. Caringi

P. Castera

R.K. Choudhury

P. Chung

O. Chvala

Z. Conesa del Valle

P. Constantin

T. Dahms

S. Dairaku

I. Danchev

K. Das

M.K. Dayananda

K.V. Dharmawardane

Brazil

O. Dietzsch

M. Donadelli

Measurement of jet-medium interactions via direct photon-hadron correlations in <math><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> and <math><mrow><mi>d</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>200</mn></mrow></math> GeV

Charmonium is a valuable probe in heavy-ion collisions to study the properties of the quark gluon plasma, and is also an interesting probe in small collision systems to study cold nuclear matter effects, which are also present in large collision systems. With the recent observations of collective behavior of produced particles in small system collisions, measurements of the modification of charmonium in small systems have become increasingly relevant. We present the results of <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> measurements at forward and backward rapidity in various small collision systems, <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math>, <math><mrow><mi>p</mi><mo>+</mo><mi>Al</mi></mrow></math>, <math><mrow><mi>p</mi><mo>+</mo><mi>Au</mi></mrow></math>, and <math><mrow><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>+</mo><mi>Au</mi></mrow></math>, at <math><mrow><msqrt><msub><mi>s</mi><msub><mrow></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msub></msqrt><mo>=</mo><mn>200</mn></mrow></math> GeV. The results are presented in the form of the observable <math><msub><mi>R</mi><mrow><mi>A</mi><mi>B</mi></mrow></msub></math>, the nuclear modification factor, a measure of the ratio of the <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> invariant yield compared to the scaled yield in <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math> collisions. We examine the rapidity, transverse momentum, and collision centrality dependence of nuclear effects on <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> production with different projectile sizes <math><mi>p</mi></math> and <math><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts></math>, and different target sizes Al and Au. The modification is found to be strongly dependent on the target size, but to be very similar for <math><mrow><mi>p</mi><mo>+</mo><mi>Au</mi></mrow></math> and <math><mrow><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>+</mo><mi>Au</mi></mrow></math>. However, for 0%–20% central collisions at backward rapidity, the modification factor for <math><mrow><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>+</mo><mi>Au</mi></mrow></math> is found to be smaller than that for <math><mrow><mi>p</mi><mo>+</mo><mi>Au</mi></mrow></math>, with a mean fit to the ratio of <math><mrow><mn>0.89</mn><mo>±</mo><mn>0.03</mn></mrow></math>(stat)<math><mrow><mo>±</mo><mn>0.08</mn></mrow></math>(syst), possibly indicating final state effects due to the larger projectile size.

E.A. Gamez

Measurement of <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> at forward and backward rapidity in <math><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math>, <math><mrow><mi>p</mi><mo>+</mo><mi>Al</mi></mrow></math>, <math><mrow><mi>p</mi><mo>+</mo><mi>Au</mi></mrow></math>, and <math><mrow><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>+</mo><mi>Au</mi></mrow></math> collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>200</mn></mrow></math> GeV