Measurements of mass and angular distributions of fission fragments from actinide nuclei $^{249}$Bk and $^{257}$Md, produced in fusion reactions $^{11}$B and $^{19}$F + $^{238}$U, are presented. Experimentally observed mass ratio distributions indicate “multi-chance fission” through the interplay of fission modes in the fission process, and they agree well with predictions from calculations using the GEF (“GEneral description of Fission observables”) model code. Furthermore, to test the signatures of events from non-compound nuclear processes in the fission of $^{249}$Bk and $^{257}$Md nuclei, Monte Carlo statistical decay model calculations using GEMINI$^{++}$ were performed for the measured mass distribution at all energies. For comparison purposes, the fission fragment mass distributions of neighboring heavy actinide nuclei, previously measured in the fission of $^{250}$Cf and $^{254}$Fm nuclei produced by $^{12}$C and $^{16}$O projectiles on a $^{238}$U target, are also presented. The measured angular anisotropy data for the $^{19}$F + $^{238}$U reaction differ from the results of the Transition State Model (TSM) at energies below the fusion barrier. As a result of the present study, we suggest considering the interplay between K relaxation time, dynamic dissipation, and their influence on shell correction to understand the evolution of fission dynamics in heavy-ion-induced actinide nuclei.

Poland

R. Dubey

France

G. Kaur

India

Abhishek Yadav

N. Saneesh

Akhil Jhingan

P. Sugathan

Italy

Tathagata Banerjee

K.S. Golda

Hardev Singh

Meenu Thakur

United States

Ruchi Mahajan

Re-investigation of the interplay of fission modes and non-equilibrium fission processes in heavy actinide nuclei Bk and Md

This paper presents a comprehensive analysis of the MD-BFKL equation, considering both shadowing and anti-shadowing effects in gluon recombination processes. By deriving analytical expressions for unintegrated gluon distributions through the solution of the MD-BFKL equation, with and without the incorporation of the anti-shadowing effect, we offer new insights into the influence of these effects on the behavior of unintegrated gluon distributions. Our results, when compared to those from the CT18NLO gluon distribution function, demonstrate that the anti-shadowing effect has a notably stronger impact on the characteristics of unintegrated gluon distributions, particularly in regions of high rapidity and momentum. This work significantly contributes to the understanding of gluon recombination mechanisms and their implications in high energy physics.

China

Xiaopeng Wang

Yanbing Cai

Xurong Chen

Exploring the impact of anti-shadowing effect on unintegrated gluon distributions in the MD-BFKL equation  

Measurements of mass and Λ binding energy of <math altimg='si4.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></msubsup></math>H and <math altimg='si4.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></msubsup></math>He in Au+Au collisions at <math altimg='si5.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi mathvariant='normal'>NN</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>3</mn></math> GeV are presented, with an aim to address the charge symmetry breaking (CSB) problem in hypernuclei systems with atomic number <italic>A</italic> = 4. The &#923; binding energies are measured to be <math altimg='si6.svg'><mn>2.22</mn><mo>&#177;</mo><mn>0.06</mn></math>(stat.)&#177;0.14(syst.) MeV and <math altimg='si7.svg'><mn>2.38</mn><mo>&#177;</mo><mn>0.13</mn></math>(stat.)&#177;0.12(syst.) MeV for <math altimg='si4.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></msubsup></math>H and <math altimg='si4.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></msubsup></math>He, respectively. The measured &#923; binding-energy difference is <math altimg='si8.svg'><mn>0.16</mn><mo>&#177;</mo><mn>0.14</mn><mo stretchy='false'>(</mo><mtext>stat</mtext><mo>.</mo><mo stretchy='false'>)</mo><mo>&#177;</mo><mn>0.10</mn><mo stretchy='false'>(</mo><mtext>syst</mtext><mo>.</mo><mo stretchy='false'>)</mo></math> MeV for ground states. Combined with the <italic>&#947;</italic>-ray transition energies, the binding-energy difference for excited states is <math altimg='si9.svg'><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mn>0.16</mn><mo>&#177;</mo><mn>0.14</mn><mo stretchy='false'>(</mo><mtext>stat</mtext><mo>.</mo><mo stretchy='false'>)</mo><mo>&#177;</mo><mn>0.10</mn><mo stretchy='false'>(</mo><mtext>syst</mtext><mo>.</mo><mo stretchy='false'>)</mo></math> MeV, which is negative and comparable to the value of the ground states within uncertainties. These new measurements on the &#923; binding-energy difference in A = 4 hypernuclei systems are consistent with the theoretical calculations that result in <math altimg='si10.svg'><mi mathvariant='normal'>&#916;</mi><msubsup><mrow><mi mathvariant='normal'>B</mi></mrow><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></msubsup><mo stretchy='false'>(</mo><msubsup><mrow><mn>1</mn></mrow><mrow><mtext>exc</mtext></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup><mo stretchy='false'>)</mo><mo>&#8776;</mo><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi mathvariant='normal'>&#916;</mi><msubsup><mrow><mtext>B</mtext></mrow><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></msubsup><mo stretchy='false'>(</mo><msubsup><mrow><mn>0</mn></mrow><mrow><mtext>g.s.</mtext></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>&lt;</mo><mn>0</mn></math> and present a new method for the study of CSB effect using relativistic heavy-ion collisions.

Egypt

M.S. Abdallah

Hungary

Brazil

Czechia

Germany

Chile

Japan

B.E. Aboona

J. Adam

L. Adamczyk

J.R. Adams

J.K. Adkins

I. Aggarwal

M.M. Aggarwal

Z. Ahammed

D.M. Anderson

E.C. Aschenauer

M.U. Ashraf

J. Atchison

V. Bairathi

W. Baker

J.G. Ball Cap

K. Barish

A. Behera

R. Bellwied

P. Bhagat

A. Bhasin

J. Bielcik

J. Bielcikova

J.D. Brandenburg

X.Z. Cai

H. Caines

M. Calderón de la Barca Sánchez

D. Cebra

I. Chakaberia

P. Chaloupka

B.K. Chan

Z. Chang

A. Chatterjee

S. Chattopadhyay

D. Chen

J. Chen

J.H. Chen

X. Chen

Z. Chen

J. Cheng

S. Choudhury

W. Christie

X. Chu

H.J. Crawford

M. Csanád

M. Daugherity

I.M. Deppner

A. Dhamija

L. Di Carlo

L. Didenko

P. Dixit

X. Dong

J.L. Drachenberg

E. Duckworth

J.C. Dunlop

J. Engelage

G. Eppley

S. Esumi

O. Evdokimov

A. Ewigleben

O. Eyser

R. Fatemi

F.M. Fawzi

S. Fazio

C.J. Feng

Y. Feng

E. Finch

Y. Fisyak

A. Francisco

C. Fu

C.A. Gagliardi

T. Galatyuk

F. Geurts

N. Ghimire

A. Gibson

K. Gopal

X. Gou

D. Grosnick

A. Gupta

W. Guryn

A. Hamed

Y. Han

S. Harabasz

M.D. Harasty

J.W. Harris

H. Harrison

S. He

W. He

X.H. He

Y. He

S. Heppelmann

N. Herrmann

E. Hoffman

L. Holub

C. Hu

Q. Hu

Y. Hu

H. Huang

H.Z. Huang

S.L. Huang

Measurement of <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>H</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> and <math altimg='si2.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> binding energy in Au+Au collisions at <math altimg='si3.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi mathvariant='normal'>NN</mi></mrow></msub></mrow></msqrt></math> = 3 GeV

M. Abdallah

B. Aboona

J. Adams

J. Adkins

M. Aggarwal

D. Anderson

E. Aschenauer

X. Bai

J. Ball Cap

S. Bhatta

J. Brandenburg

X. Cai

M. Barca Sánchez

B. Chan

Y. Cheng

H. Crawford

I. Deppner

L. Carlo

J. Drachenberg

J. Dunlop

F. Fawzi

Taiwan

C. Feng

C. Gagliardi

M. Harasty

J. Harris

X. He

Erratum to: Evidence of Mass Ordering of Charm and Bottom Quark Energy Loss in Au+Au Collisions at RHIC

A decisive experimental test of the Chiral Magnetic Effect (CME) is considered one of the major scientific goals at the Relativistic Heavy-Ion Collider (RHIC) towards understanding the nontrivial topological fluctuations of the Quantum Chromodynamics vacuum. In heavy-ion collisions, the CME is expected to result in a charge separation phenomenon across the reaction plane, whose strength could be strongly energy dependent. The previous CME searches have been focused on top RHIC energy collisions. In this Letter, we present a low energy search for the CME in Au+Au collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><msub><mrow></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msub></mrow></msqrt><mo>=</mo><mn>27</mn></math> GeV. We measure elliptic flow scaled charge-dependent correlators relative to the event planes that are defined at both mid-rapidity <math><mo>|</mo><mi>η</mi><mo>|</mo><mo>&lt;</mo><mn>1.0</mn></math> and at forward rapidity <math><mn>2.1</mn><mo>&lt;</mo><mo>|</mo><mi>η</mi><mo>|</mo><mo>&lt;</mo><mn>5.1</mn></math>. We compare the results based on the directed flow plane (<math><msub><mrow><mi>Ψ</mi></mrow><mrow><mn>1</mn></mrow></msub></math>) at forward rapidity and the elliptic flow plane (<math><msub><mrow><mi>Ψ</mi></mrow><mrow><mn>2</mn></mrow></msub></math>) at both central and forward rapidity. The CME scenario is expected to result in a larger correlation relative to <math><msub><mrow><mi>Ψ</mi></mrow><mrow><mn>1</mn></mrow></msub></math> than to <math><msub><mrow><mi>Ψ</mi></mrow><mrow><mn>2</mn></mrow></msub></math>, while a flow driven background scenario would lead to a consistent result for both event planes. In 10-50% centrality, results using three different event planes are found to be consistent within experimental uncertainties, suggesting a flow driven background scenario dominating the measurement. We obtain an upper limit on the deviation from a flow driven background scenario at the 95% confidence level. This work opens up a possible road map towards future CME search with the high statistics data from the RHIC Beam Energy Scan Phase-II.

J. Ceska

G. Dale-Gau

A. Das

F.A. Flor

T. Huang

X. Huang

Y. Huang

T.J. Humanic

D. Isenhower

Search for the chiral magnetic effect in Au+Au collisions at GeV with the STAR forward event plane detectors

The linear and mode-coupled contributions to higher-order anisotropic flow are presented for Au+Au collisions at <math><msqrt><mrow><msub><mrow><mtext>s</mtext></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt></math> = 27, 39, 54.4, and 200 GeV and compared to similar measurements for Pb+Pb collisions at the Large Hadron Collider (LHC). The coefficients and the flow harmonics' correlations, which characterize the linear and mode-coupled response to the lower-order anisotropies, indicate a beam energy dependence consistent with an influence from the specific shear viscosity (<math><mi>η</mi><mo>/</mo><mi>s</mi></math>). In contrast, the dimensionless coefficients, mode-coupled response coefficients, and normalized symmetric cumulants are approximately beam-energy independent, consistent with a significant role from initial-state effects. These measurements could provide unique supplemental constraints to (i) distinguish between different initial-state models and (ii) delineate the temperature (T) and baryon chemical potential (<math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math>) dependence of the specific shear viscosity <math><mfrac><mrow><mi>η</mi></mrow><mrow><mi>s</mi></mrow></mfrac><mo>(</mo><mi>T</mi><mo>,</mo><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub><mo>)</mo></math>.

JINR

G. Agakishiev

A. Aitbaev

Russia

I. Alekseev

A. Aparin

G.S. Averichev

I.G. Bordyuzhin

A.V. Brandin

T.G. Dedovich

A.A. Derevschikov

M. Isshiki

W.W. Jacobs

A. Jalotra

Beam energy dependence of the linear and mode-coupled flow harmonics in Au+Au collisions

Partons traversing the strongly interacting medium produced in heavy-ion collisions are expected to lose energy depending on their color charge and mass. We measure the nuclear modification factors for charm- and bottom-decay electrons, defined as the ratio of yields, divided by the number of binary nucleon–nucleon collisions, in  $$\sqrt{s_{\textrm{NN}}}=200$$  <math> <mrow> <msqrt> <msub> <mi>s</mi> <mtext>NN</mtext> </msub> </msqrt> <mo>=</mo> <mn>200</mn> </mrow> </math>   GeV Au+Au collisions to p+p collisions ( $$R_{\textrm{AA}}$$  <math> <msub> <mi>R</mi> <mtext>AA</mtext> </msub> </math>  ), or in central to peripheral Au+Au collisions ( $$R_{\textrm{CP}}$$  <math> <msub> <mi>R</mi> <mtext>CP</mtext> </msub> </math>  ). We find the bottom-decay electron  $$R_{\textrm{AA}}$$  <math> <msub> <mi>R</mi> <mtext>AA</mtext> </msub> </math>   and  $$R_{\textrm{CP}}$$  <math> <msub> <mi>R</mi> <mtext>CP</mtext> </msub> </math>   to be significantly higher than those of charm-decay electrons. Model calculations including mass-dependent parton energy loss in a strongly coupled medium are consistent with the measured data. These observations provide evidence of mass ordering of charm and bottom quark energy loss when traversing through the strongly coupled medium created in heavy-ion collisions.

Evidence of Mass Ordering of Charm and Bottom Quark Energy Loss in Au+Au Collisions at RHIC

The STAR Collaboration reports measurements of the transverse single-spin asymmetries, <math><msub><mi>A</mi><mi>N</mi></msub></math>, for inclusive jets and identified “hadrons within jets” production at midrapidity from transversely polarized <math><mi>p</mi><mi>p</mi></math> collisions at <math><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, based on data recorded in 2012 and 2015. The inclusive jet asymmetry measurements include <math><msub><mi>A</mi><mi>N</mi></msub></math> for inclusive jets and <math><msub><mi>A</mi><mi>N</mi></msub></math> for jets containing a charged pion carrying a momentum fraction <math><mi>z</mi><mo>&gt;</mo><mn>0.3</mn></math> of the jet momentum. The identified hadron within jet asymmetry measurements include the Collins effect for charged pions, kaons, and protons, and the Collins-like effect for charged pions. The measured asymmetries are determined for several distinct kinematic regions characterized by the jet transverse momentum <math><msub><mi>p</mi><mi>T</mi></msub></math> and pseudorapidity <math><mi>η</mi></math>, as well as the hadron momentum fraction <math><mi>z</mi></math> and momentum transverse to the jet axis <math><msub><mi>j</mi><mi>T</mi></msub></math>. These results probe higher momentum scales (<math><msup><mi>Q</mi><mn>2</mn></msup></math> up to <math><mo>∼</mo><mn>900</mn><mtext> </mtext><mtext> </mtext><msup><mi>GeV</mi><mn>2</mn></msup></math>) than current, semi-inclusive deep-inelastic scattering measurements, and they provide new constraints on quark transversity in the proton and enable tests of evolution, universality, and factorization breaking in the transverse-momentum-dependent formalism.

M. S. Abdallah

B. E. Aboona

J. R. Adams

J. K. Adkins

M. M. Aggarwal

D. M. Anderson

E. C. Aschenauer

M. U. Ashraf

J. G. Ball Cap

J. D. Brandenburg

Azimuthal transverse single-spin asymmetries of inclusive jets and identified hadrons within jets from polarized <math><mi>p</mi><mi>p</mi></math> collisions at <math><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>