An extensive analysis of HYDJET++ generated heavy-ion collision data at collider energies is carried out using Takagi moment method based multifractal analysis approach, to search for the presence of local density fluctuations. We report first analysis on multifractality in Au-Au collisions for the RHIC energies, <math altimg='si10.svg'><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo linebreak='goodbreak'>=</mo><mn>14.5</mn></mrow></math> to 200&#8239;GeV and in Pb-Pb collisions at LHC energies, <math altimg='si4.svg'><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo linebreak='goodbreak'>=</mo><mn>2.76</mn></mrow></math> to 5.02 TeV in two-dimensional ( <math altimg='si6.svg'><mrow><mi>&#951;</mi><mo linebreak='goodbreak'>&#8722;</mo><mi>&#981;</mi></mrow></math>) phase-space. The generalized dimension <italic>D<inf>q</inf></italic> for different orders q at different centralities have been calculated using the methodology proposed by Takagi. The calculated <italic>D<inf>q</inf></italic> values are found to exhibit collision energy as well as centrality dependent behaviour and analysis suggests the multifractal behaviour of charged particle spectra at collider energies. The linear dependence of the <italic>D<inf>q</inf></italic> values as a function of ln <math altimg='si11.svg'><mfrac><mi>q</mi><mrow><mo>(</mo><mi>q</mi><mo>&#8722;</mo><mn>1</mn><mo>)</mo></mrow></mfrac></math> favours the multifractal Bernoulli representation and the values of multifractal specific heat, c, have been extracted from the <italic>D<inf>q</inf></italic> values to perform a comparative analysis with the available experimental data and other model results at collider energies. A slowly decreasing trend of the c values with increasing beam energy is observed for nuclear collisions at collider energies. In addition to this, the centrality dependent behaviour of the HYDJET++ calculated &#8217;c&#8217; values is observed for A-A collisions at collider energies. Further, Ginzberg-Landau (GL) theory framework is utilised here to analyse the dynamics of the HYDJET++ simulated A-A collisions at considered RHIC and LHC energies. A comparative analysis of the HYDJET++ calculated value of the critical exponent &#8217; <italic>&#957;</italic>&#8217;, with other model calculations and with the reported experimental measurements is also presented. The &#8217; <italic>&#957;</italic>&#8217; values calculated in the present analysis exhibit approximately a constant value less than the value predicted by GL thoery for the considered RHIC and LHC energies, whereas it is quite close to 1 at LHC energies, agreeing well with the value predicted by 2D Ising model.

India

Anuj Chandra

Ashwini Kumar

Sweta Singh

Shakeel Ahmad

B.K. Singh

Multifractal analysis of heavy-ion collisions at RHIC and LHC energies

Recent measurements of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production as a function of event charged-particle multiplicity at the collision energies of both the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) show enhanced <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production yields with increasing multiplicity. One potential explanation for this type of dependence is multiparton interactions (MPI). We present the first study of potential autocorrelations at RHIC energies and forward and backward rapidity of self-normalized <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> yields and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> ratio, as a function of self-normalized multiplicity in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mo>+</mo><mi>p</mi></math> collisions. In addition, detailed pythia studies tuned to RHIC energies were performed to investigate the MPI impacts. We find that the PHENIX data at RHIC are consistent with recent LHC measurements and can only be described by pythia calculations that include MPI effects. The forward and backward <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> ratio is found to be less dependent on the charged-particle multiplicity.

Hungary

N.J. Abdulameer

United States

U. Acharya

C. Aidala

Japan

Y. Akiba

M. Alfred

V. Andrieux

Russia

S. Antsupov

N. Apadula

H. Asano

B. Azmoun

V. Babintsev

N.S. Bandara

E. Bannikov

K.N. Barish

S. Bathe

A. Bazilevsky

M. Beaumier

R. Belmont

A. Berdnikov

Y. Berdnikov

L. Bichon

B. Blankenship

D.S. Blau

J.S. Bok

V. Borisov

M.L. Brooks

J. Bryslawskyj

V. Bumazhnov

S. Campbell

R. Cervantes

D. Chen

M. Chiu

C.Y. Chi

I.J. Choi

South Korea

J.B. Choi

Israel

Z. Citron

M. Connors

R. Corliss

N. Cronin

M. Csanád

T. Csörgő

T.W. Danley

M.S. Daugherity

G. David

K. DeBlasio

K. Dehmelt

A. Denisov

A. Deshpande

E.J. Desmond

A. Dion

D. Dixit

V. Doomra

J.H. Do

A. Drees

K.A. Drees

J.M. Durham

A. Durum

H. En’yo

A. Enokizono

R. Esha

B. Fadem

W. Fan

N. Feege

D.E. Fields

Czechia

M. Finger

D. Firak

D. Fitzgerald

S.L. Fokin

J.E. Frantz

A. Franz

A.D. Frawley

Y. Fukuda

P. Gallus

C. Gal

P. Garg

H. Ge

F. Giordano

Y. Goto

N. Grau

S.V. Greene

M. Grosse Perdekamp

T. Gunji

T. Guo

H. Guragain

T. Hachiya

J.S. Haggerty

K.I. Hahn

H. Hamagaki

H.F. Hamilton

J. Hanks

S.Y. Han

S. Hasegawa

T.O.S. Haseler

T.K. Hemmick

X. He

J.C. Hill

K. Hill

A. Hodges

R.S. Hollis

Multiplicity dependent <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> production at forward and backward rapidity 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>

For the present work, we have used the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>HYDJET</mi><mo>+</mo><mo>+</mo></mrow></math> model to explore the production of pure multi-strange hadrons in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>2.76</mn></mrow></math> TeV and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>5.02</mn></mrow></math> TeV collision energies, respectively. We have performed simulations to investigate transverse momentum (<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math>) spectra and elliptic flow (<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub></math>) for <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ϕ</mi></math> mesons and <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Ω</mi></math> baryons, and compared the results both with the ALICE experimental data and available model predictions for selected central classes. Furthermore, we have calculated the nuclear modification factors (<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>C</mi><mi>P</mi></mrow></msub></math>), which provide a perception of jet quenching phenomena. Hence, our findings enable the study of the energy and system dependence of <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ϕ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Ω</mi></math> hadrons production over a wide range of ultrarelativistic collision energies. We also present the particle ratios (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">Ω</mi><mo>/</mo><mi>ϕ</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mover><mi mathvariant="normal">Ω</mi><mo>¯</mo></mover><mo>+</mo></msup><mo>/</mo><msup><mi mathvariant="normal">Ω</mi><mo>−</mo></msup></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">Ω</mi><mo>/</mo><mi>π</mi></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ϕ</mi><mo>/</mo><mi>π</mi></mrow></math>), offering insights into the strangeness enhancement and chemical properties of the medium at both CERN Large Hadron Collider collision energies. Additionally, we also explore the predictions for the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Ω</mi></math> baryon in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>5.02</mn></mrow></math> TeV, focusing on <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>C</mi><mi>P</mi></mrow></msub></math>, and particle ratios within the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>HYDJET</mi><mo>+</mo><mo>+</mo></mrow></math> framework, offering insights into future measurements and particle dynamics in high-energy heavy-ion collisions.

Gauri Devi

Production of multistrange hadrons in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at energies available at the CERN Large Hadron Collider using the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>HYDJET</mi><mo>+</mo><mo>+</mo></mrow></math> model

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.

N.N. Ajitanand

R. Akimoto

J. Alexander

K. Aoki

E.T. Atomssa

T.C. Awes

M. Bai

China

X. Bai

B. Bannier

V. Baublis

C. Baumann

S. Baumgart

D. Black

K. Boyle

H. Buesching

S. Butsyk

C.H. Chen

S. Choi

Sweden

P. Christiansen

T. Chujo

V. Cianciolo

B.A. Cole

N. Crossette

L. D’Orazio

A. Datta

L. Ding

France

O. Drapier

T. Engelmore

K.O. Eyser

F. Fleuret

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.

Satya Ranjan Nayak

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

M. Giles

A. Glenn

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

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