Jet-associated deuteron production in pp collisions at <math><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn></math> TeV and p-Pb collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.02</mn></math> TeV is studied in the coalescence model by using the phase-space information of proton and neutron pairs from a multiphase transport (AMPT) model at the kinetic freezeout. In the low transverse momentum (<math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>) region <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>/</mo><mi>A</mi><mo>&lt;</mo><mn>1.5</mn></math> GeV/c, where A is the mass number of a nucleus, the in-jet coalescence factor <math><msubsup><mrow><mi>B</mi></mrow><mrow><mn>2</mn></mrow><mrow><mtext>In-jet</mtext></mrow></msubsup></math> for deuteron production, given by the ratio of the in-jet deuteron number to the square of the in-jet proton number, is found to be larger than the coalescence factor <math><msub><mrow><mi>B</mi></mrow><mrow><mn>2</mn></mrow></msub></math> in the medium perpendicular to the jet by a factor of about 10 in pp collisions and of 25 in p−Pb collisions, which are consistent with the ALICE measurements at the LHC. Such large low-momentum enhancements mainly come from coalescence of nucleons inside the jet with the medium nucleons. Coalescence of nucleons inside the jet dominates deuteron production only at the higher <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> region of <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>/</mo><mi>A</mi><mo>≳</mo><mn>4</mn></math> GeV/c, where both the yield ratio <math><mi>d</mi><mo>/</mo><mi>p</mi></math> of deuteron to proton numbers and the <math><msub><mrow><mi>B</mi></mrow><mrow><mn>2</mn></mrow></msub></math> are also significantly larger in the jet direction than in the direction perpendicular to the jet due to the strong collinear correlation among particles produced from jet fragmentation. Studying jet-associated deuteron production in relativistic nuclear collisions thus opens up a new window to probe the phase-space structure of nucleons inside jets.

China

Yi-Heng Feng

United States

Che Ming Ko

Yu-Gang Ma

Kai-Jia Sun

Xin-Nian Wang

Zhong Yang

Song Zhang

Jet-induced enhancement of deuteron production in And -Pb collisions at the LHC

Momentum correlation functions between <math><mi>π</mi><mo>,</mo><mo> </mo><mi>K</mi></math>, and <math><mi>p</mi></math> are calculated for several heavy-ion collision systems, namely <math><mrow><mmultiscripts><mi>B</mi><mprescripts></mprescripts><mn>5</mn><mn>10</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>B</mi><mprescripts></mprescripts><mn>5</mn><mn>10</mn></mmultiscripts></mrow><mo>,</mo><mo> </mo><mrow><mmultiscripts><mi>O</mi><mprescripts></mprescripts><mn>8</mn><mn>16</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>O</mi><mprescripts></mprescripts><mn>8</mn><mn>16</mn></mmultiscripts></mrow><mo>,</mo><mo> </mo><mrow><mmultiscripts><mi>Ca</mi><mprescripts></mprescripts><mn>20</mn><mn>40</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>Ca</mi><mprescripts></mprescripts><mn>20</mn><mn>40</mn></mmultiscripts></mrow></math>, and <math><mrow><mmultiscripts><mi>Au</mi><mprescripts></mprescripts><mn>79</mn><mn>197</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>Au</mi><mprescripts></mprescripts><mn>79</mn><mn>197</mn></mmultiscripts></mrow></math> in central collisions as well as <math><mrow><mmultiscripts><mi>Au</mi><mprescripts></mprescripts><mn>79</mn><mn>197</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>Au</mi><mprescripts></mprescripts><mn>79</mn><mn>197</mn></mmultiscripts></mrow></math> collision in different centralities at center-of-mass energy <math><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>39</mn></math> GeV within the framework of a multiphase transport model complemented by the Lednický and Lyuboshitz analytical method. The results present the centrality and system-size dependence of the momentum correlation functions among pairs of <math><mi>π</mi><mo>,</mo><mo> </mo><mi>K</mi></math>, and <math><mi>p</mi></math>, from which the emission source-size can be deduced. It is found that the deduced source sizes increase with the decreasing of centrality for Au <math><mo>+</mo></math> Au system or with the increasing of system size in central collisions with different nuclear size. In addition, through the momentum correlation functions of nonidentical particle pairs gated on velocity, the average emission sequence of nonidentical particles can be indicated. The results illustrate that in the small relative momentum region, protons are emitted in average earlier than <math><msup><mi>π</mi><mo>+</mo></msup></math> and <math><msup><mi>K</mi><mo>+</mo></msup></math>, and <math><msup><mi>K</mi><mo>+</mo></msup></math> are emitted averagely earlier than <math><msup><mi>π</mi><mo>+</mo></msup></math>. Furthermore, it seems that larger interval of the average emission order among them is exhibited for smaller collision systems. The present study sheds light on the dynamics of light particle emission at RHIC energy.

Ting-Ting Wang

Calculation of momentum correlation functions between <math><mi>π</mi><mo>,</mo><mo> </mo><mi>K</mi></math>, and <math><mi>p</mi></math> for several heavy-ion collision systems at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>39</mn></mrow></math> GeV

The longitudinal asymmetry in relativistic heavy ion collisions arises from the fluctuation in the number of nucleons involved. This asymmetry causes a rapidity shift in the center of mass of the participating zone. Both the rapidity shift and the longitudinal asymmetry have been found to be significant at the top CERN Large Hadron Collider (LHC) energy for collisions of identical nuclei, and the longitudinal asymmetry is important for reconstructing the colliding vertex and correcting the rapidity shift. However, much discussion of the longitudinal asymmetry has treated the initial condition as a nonzero momentum contributed only by the number of participants, i.e., the asymmetry depends only on the number of participating nucleons. So we naturally raise a physical problem, can other initial conditions, such as two typical initial conditions for nuclei, geometric configuration, and momentum distribution, provide effects on the longitudinal asymmetry? Therefore, in this work we consider other effects on the longitudinal asymmetry other than the fluctuation in the number of participants, e.g., the <math><mi>α</mi></math> clustering structure as well as the intrinsic momentum distribution in the target and projectile nuclei for the collisions in the framework of a multiphase transport (AMPT) model. By introducing systems with different <math><mi>α</mi></math>-clustering structure and intrinsic momentum distribution, we calculated the ratio of the rapidity distributions of different systems and extracted expansion coefficients to analyze the difference contributed by these factors. We also investigated the possible effect of the non-Gaussian distribution on the rapidity distribution. These results can help us to constrain the initial conditions and reconstruct the colliding vertex in ultrarelativistic heavy ion collisions, and suggest a quantitative correction on the final state measurement and a possible correlation between the initial condition and the final state observable in LHC and BNL Relativistic Heavy Ion Collider energy.

Ru-Xin Cao

Effects of the <math><mi>α</mi></math>-cluster structure and the intrinsic momentum component of nuclei on the longitudinal asymmetry in relativistic heavy-ion collisions

Momentum correlation functions of light (anti)nuclei formed by the coalescence mechanism of (anti)nucleons are calculated for several central heavy-ion collision systems, namely <math><mrow><msubsup><mrow></mrow><mrow><mn>5</mn></mrow><mn>10</mn></msubsup><mtext>B</mtext><mo>+</mo><msubsup><mrow></mrow><mrow><mn>5</mn></mrow><mn>10</mn></msubsup><mtext>B</mtext></mrow></math>, <math><mrow><msubsup><mrow></mrow><mrow><mn>8</mn></mrow><mn>16</mn></msubsup><mtext>O</mtext><mo>+</mo><msubsup><mrow></mrow><mrow><mn>8</mn></mrow><mn>16</mn></msubsup><mtext>O</mtext></mrow></math>, <math><mrow><msubsup><mrow></mrow><mrow><mn>20</mn></mrow><mn>40</mn></msubsup><mtext>Ca</mtext><mo>+</mo><msubsup><mrow></mrow><mrow><mn>20</mn></mrow><mn>40</mn></msubsup><mtext>Ca</mtext></mrow></math>, as well as <math><mrow><msubsup><mrow></mrow><mrow><mn>79</mn></mrow><mn>197</mn></msubsup><mtext>Au</mtext><mo>+</mo><msubsup><mrow></mrow><mrow><mn>79</mn></mrow><mn>197</mn></msubsup><mtext>Au</mtext></mrow></math> in different centralities at center-of-mass energy <math><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt></math> = 39 GeV within the framework of a multiphase transport (AMPT) model complemented by the Lednický and Lyuboshitz analytical method. Momentum correlation functions for identical or nonidentical light (anti)nuclei are constructed and analyzed for the above collision systems. The Au+Au results demonstrate that emission of light (anti)nuclei occurs from a source with smaller space extent in more peripheral collisions. The effect of system size on the momentum correlation functions of identical or nonidentical light (anti)nuclei is also explored by several collision system in central collisions. The results indicate that the emission source size of light (anti)nuclei pairs deduced from their momentum correlation functions and system size is self-consistent. Momentum correlation functions of nonidentical light nuclei pairs gated on velocity are applied to infer the average emission sequence of them. The results illustrate that protons are emitted on average on a timescale similar to neutrons but earlier than deuterons or tritons in the small relative momentum region. In addition, a larger interval of the average emission order among them is exhibited for smaller collision systems or at more peripheral collisions.

Simulations of momentum correlation functions of light (anti)nuclei in relativistic heavy-ion collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>39</mn></mrow></math> GeV

A collision system scan involving α-clustered $^{12}$C and $^{16}$O is studied by using a multiphase transport model for central collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>6.37</mn></math> TeV. Background subtracted away-side dihadron azimuthal correlation is performed via the zero yield at minimum (ZYAM) method from raw signals, and the quantitative parameters, such as RMS width and Kurtosis, seem nicely follow the <math><msup><mrow><mi>A</mi></mrow><mrow><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn></mrow></msup></math> law of the system size if the nucleus has the normal Woods-Saxon nucleon distribution. However, for α-clustering light nuclei, specifically for $^{12}$C and $^{16}$O, the RMS width and Kurtosis of away-side azimuthal correlation are deviated from the baseline of <math><msup><mrow><mi>A</mi></mrow><mrow><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn></mrow></msup></math> law. In addition, the momentum dependence of away-side broadening parameters is also presented. The results show that there is a distinction in away-side broadening parameters of dihadron correlation function between the Woods-Saxon distribution and the α-clustered structures, which sheds light on that the collision system scan for dihadron azimuthal correlation as a potential probe to distinguish α-clustered nuclei.

Yuan-Zhe Wang

System dependence of away-side broadening and -clustering Light Nuclei Structure Effect in Dihadron Azimuthal Correlations

Even though lots of  $$\Lambda $$  <math> <mi>Λ</mi> </math>  -hypernuclei have been found and measured, multi-strangeness hypernuclei consisting of  $$\Omega $$  <math> <mi>Ω</mi> </math>   are not yet discovered. The studies of multi-strangeness hypernuclei help us further understand the interaction between hyperons and nucleons. Recently the  $$\Omega N$$  <math> <mrow> <mi>Ω</mi> <mi>N</mi> </mrow> </math>   and  $$\Omega \Omega $$  <math> <mrow> <mi>Ω</mi> <mi>Ω</mi> </mrow> </math>   interactions as well as binding energies were calculated by the HAL-QCD’s lattice Quantum Chromo-Dynamics (LQCD) simulations and production rates of  $$\Omega $$  <math> <mi>Ω</mi> </math>  -dibaryon in Au + Au collisions at RHIC and Pb + Pb collisions at LHC energies were estimated by a coalescence model. The present work discusses the production of more exotic triple-baryons including  $$\Omega $$  <math> <mi>Ω</mi> </math>  , namely  $$\Omega NN$$  <math> <mrow> <mi>Ω</mi> <mi>N</mi> <mi>N</mi> </mrow> </math>   and  $$\Omega \Omega N$$  <math> <mrow> <mi>Ω</mi> <mi>Ω</mi> <mi>N</mi> </mrow> </math>   as well as their decay channels. A variation method is used in calculations of bound states and binding energy of  $$\Omega NN$$  <math> <mrow> <mi>Ω</mi> <mi>N</mi> <mi>N</mi> </mrow> </math>   and  $$\Omega \Omega N$$  <math> <mrow> <mi>Ω</mi> <mi>Ω</mi> <mi>N</mi> </mrow> </math>   with the potentials from the HAL-QCD’s results. The productions of  $$\Omega NN$$  <math> <mrow> <mi>Ω</mi> <mi>N</mi> <mi>N</mi> </mrow> </math>   and  $$\Omega \Omega N$$  <math> <mrow> <mi>Ω</mi> <mi>Ω</mi> <mi>N</mi> </mrow> </math>   are predicted by using a blast-wave model plus coalescence model in ultra-relativistic heavy-ion collisions at  $$\sqrt{s_{NN}} = 200$$  <math> <mrow> <msqrt> <msub> <mi>s</mi> <mrow> <mi>NN</mi> </mrow> </msub> </msqrt> <mo>=</mo> <mn>200</mn> </mrow> </math>   GeV and 2.76 TeV. Furthermore, plots for baryon number dependent yields of different baryons (N and  $$\Omega $$  <math> <mi>Ω</mi> </math>  ), their dibaryons and hypernuclei are made and the production rate of a more exotic tetra-baryon ( $$\Omega \Omega NN$$  <math> <mrow> <mi>Ω</mi> <mi>Ω</mi> <mi>N</mi> <mi>N</mi> </mrow> </math>  ) is extrapolated.

Liang Zhang

Production of  $$\Omega NN$$  <math> <mrow> <mi>Ω</mi> <mi>N</mi> <mi>N</mi> </mrow> </math>   and  $$\Omega \Omega N$$  <math> <mrow> <mi>Ω</mi> <mi>Ω</mi> <mi>N</mi> </mrow> </math>   in ultra-relativistic heavy-ion collisions

The initial geometry effect on forward-backward multiplicity correlations <math><mrow><mi>C</mi><mo>(</mo><msub><mi>N</mi><mi>f</mi></msub><mo>,</mo><msub><mi>N</mi><mi>b</mi></msub><mo>)</mo></mrow></math> is studied in relativistic collisions between light nuclei by using a multiphase transport model. It is found that tetrahedron <math><mrow><mmultiscripts><mi>O</mi><mprescripts></mprescripts><none></none><mn>16</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>O</mi><mprescripts></mprescripts><none></none><mn>16</mn></mmultiscripts></mrow></math> gives a more uniform and symmetrical fireball which produces a more isotropic distribution of final particles after the expansion and evolution, and leads to a small <math><mrow><mi>C</mi><mo>(</mo><msub><mi>N</mi><mi>f</mi></msub><mo>,</mo><msub><mi>N</mi><mi>b</mi></msub><mo>)</mo></mrow></math>. Forward-backward multiplicity correlation could be taken as a useful probe to distinguish the pattern of <math><mi>α</mi></math>-clustered <math><mmultiscripts><mi>O</mi><mprescripts></mprescripts><none></none><mn>16</mn></mmultiscripts></math> in experiments by comparing the neighboring colliding nuclear systems like <math><mrow><mmultiscripts><mi>N</mi><mprescripts></mprescripts><none></none><mn>14</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>N</mi><mprescripts></mprescripts><none></none><mn>14</mn></mmultiscripts></mrow></math> and <math><mrow><mmultiscripts><mi>F</mi><mprescripts></mprescripts><none></none><mn>19</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>F</mi><mprescripts></mprescripts><none></none><mn>19</mn></mmultiscripts></mrow></math>.

Yi-An Li

Dong-Fang Wang

System evolution of forward-backward multiplicity correlations in a multiphase transport model

We study the defect groups of   <math> <msubsup> <mi>D</mi> <mi>p</mi> <mi>b</mi> </msubsup> </math>  $$ {D}_p^b $$ (G) theories using geometric engineering and BPS quivers. In the simple case when b = h ∨(G), we use the BPS quivers of the theory to see that the defect group is compatible with a known Maruyoshi-Song flow. To extend to the case where b ≠ h ∨(G), we use a similar Maruyoshi-Song flow to conjecture that the defect groups of   <math> <msubsup> <mi>D</mi> <mi>p</mi> <mi>b</mi> </msubsup> </math>  $$ {D}_p^b $$ (G) theories are given by those of G (b)[k] theories. In the cases of G = A  n , E 6, E 8 we cross check our result by calculating the BPS quivers of the G (b)[k] theories and looking at the cokernel of their intersection matrix.

United Kingdom

Saghar Hosseini

Sweden

Robert Moscrop

Maruyoshi-Song flows and defect groups of   <math> <msubsup> <mi>D</mi> <mi>p</mi> <mi>b</mi> </msubsup> </math>  $$ {\mathrm{D}}_{\mathrm{p}}^{\mathrm{b}} $$ (G) theories

<math><mi>α</mi></math>-clustering structure is a significant topic in light nuclei. A Bayesian convolutional neural network (BCNN) is applied to classify initial nonclustered and clustered configurations, namely Woods-Saxon distribution and three-<math><mi>α</mi></math> triangular (four-<math><mi>α</mi></math> tetrahedral) structure for <math><mmultiscripts><mi>C</mi><mprescripts></mprescripts><none></none><mn>12</mn></mmultiscripts></math> <math><mo>(</mo><mmultiscripts><mi>O</mi><mprescripts></mprescripts><none></none><mn>16</mn></mmultiscripts><mo>)</mo></math>, from heavy-ion collision events generated within a multiphase transport (AMPT) model. Azimuthal angle and transverse momentum distributions of charged pions are taken as inputs to train the classifier. On a multiple-event basis, the overall classification accuracy can reach <math><mrow><mn>95</mn><mo>%</mo></mrow></math> for <math><mrow><mmultiscripts><mi>C</mi><mprescripts></mprescripts><none></none><mn>12</mn></mmultiscripts><mo>/</mo><mmultiscripts><mi>O</mi><mprescripts></mprescripts><none></none><mn>16</mn></mmultiscripts><mo>+</mo><mmultiscripts><mi>Au</mi><mprescripts></mprescripts><none></none><mn>197</mn></mmultiscripts></mrow></math> events 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>. With proper constructions of samples, the predicted deviations on mixed samples with different proportions of both configurations could be within <math><mrow><mn>5</mn><mo>%</mo></mrow></math>. In addition, setting a simple confidence threshold can further improve the predictions on the mixed dataset. Our results indicate promising and extensive possibilities of application of machine-learning-based techniques to real data and some other problems in physics of heavy-ion collisions.

Junjie He

Wan-Bing He

Machine-learning-based identification for initial clustering structure in relativistic heavy-ion collisions

The charge asymmetry (<math><msub><mrow><mi>A</mi></mrow><mrow><mi>ch</mi></mrow></msub></math>) dependence of anisotropic flow serves as an important tool to search for the chiral magnetic wave (CMW) in heavy-ion collisions. However, the background effect, such as the local charge conservation (LCC) entwined with collective flow, has not yet been unambiguously eliminated in the measurement. With the help of two models, the AMPT with initial quadrupole moment and the blast wave (BW) incorporating LCC, we discuss the features of the LCC-induced and the CMW-induced correlations between <math><msub><mrow><mi>A</mi></mrow><mrow><mi>ch</mi></mrow></msub></math> and the flow. More importantly, we first propose to use the Event Shape Engineering (ESE) technique to distinguish the background and the signal for the CMW study. This method would be highly desirable in the experimental search for the CMW and provides more insights for understanding the charge-dependent collective motion of the quark-gluon plasma.