Title: D⁰ Meson Tagged Jets In Au + Au Collisions at √s_NN = 200 GeV

PAs: Diptanil Roy (Rutgers), Matthew Kelsey (ex-WSU), Sevil Salur (Rutgers), Joern Putschke (WSU)

Target Journal: PRL + PRC

Short Paper:

• Version 1 (Nov 9, 2024)
• Version 0 (Oct 15, 2024)

Long Paper: 

• Version 1 (Nov 9, 2024)
• Version 0 (Oct 15, 2024)

Analysis Note:

• Version 1 (Nov 9, 2024)
• Version 0 (Oct 15, 2024)

PWGC Preview: https://drupal.star.bnl.gov/STAR/system/files/D0Jets_Diptanil_PWGCPreview.pdf

Hard Probes Updates:
1. https://drupal.star.bnl.gov/STAR/system/files/HardProbes_Update_April4_2024.pdf [Barlow Tested Systematics]
2. https://drupal.star.bnl.gov/STAR/system/files/HardProbes_Nov30_2023_Diptanil.pdf [Consistency Checks for p_T,D⁰ bins (1,5), (5, 10) and R = 0.2]
3. https://drupal.star.bnl.gov/STAR/system/files/HardProbes_Aug10_Diptanil_v2.pdf [Data-driven prior]
4. https://drupal.star.bnl.gov/STAR/system/files/HardProbes_AnalysisMeeting_Jun27_2023_Diptanil.pdf [Spectra in different p_T,D⁰ bins]
5. https://drupal.star.bnl.gov/STAR/system/files/Diptanil_Roy_STAR_Collaboration_Meeting_2023.pdf [Changes to QM 2022 Preliminaries detailed here]
6. https://drupal.star.bnl.gov/STAR/system/files/Kelsey_JetCorr_17Mar2022.pdf
7. https://drupal.star.bnl.gov/STAR/system/files/March10_Diptanil_HFJets.pdf
8. https://drupal.star.bnl.gov/STAR/system/files/JetCorr_Embedding_Request_D0Jets_Diptanil_0.pdf

Public Presentations:
1. QM 2023: https://indico.cern.ch/event/1139644/contributions/5456348/attachments/2706841/4700613/QM2023_Poster_Diptanil_Roy.pdf
1. DNP 2022: https://drupal.star.bnl.gov/STAR/system/files/DNP_DiptanilRoy_v4.pdf
2. Hot Quarks 2022: https://drupal.star.bnl.gov/STAR/system/files/HotQuarks_DiptanilRoy_vF.pdf
3. QM 2022: https://drupal.star.bnl.gov/STAR/system/files/QMTalk_DiptanilRoy_April4_v9_0.pdf
4. DNP 2021: https://drupal.star.bnl.gov/STAR/system/files/DNP2021_Diptanil.pdf

Preliminaries:
https://drupal.star.bnl.gov/STAR/blog/droy1/Preliminary-Request-D0-Meson-Tagged-Jets-AuAu-200-GeV-0

Paper Proposal:
https://drupal.star.bnl.gov/STAR/system/files/D0Jets_Diptanil_ProposedFinalPlots.pdf [Updated]
https://drupal.star.bnl.gov/STAR/system/files/Diptanil_FallAnalysisMeeting_2023.pdf

QM 2022 Proceeding: https://arxiv.org/abs/2207.14434

PRL Abstract: Probing charm fragmentation with D⁰ Meson Tagged Charm Jets in Au + Au Collisions at √s_NN =200 GeV

Measurements of charm jets, tagged by a D⁰-meson as a constituent, are presented in this Letter for 5 < p_{T, Jet} [GeV/c] < 20 in Au + Au collisions at √s_NN = 200 GeV collected by the STAR detector at RHIC. Jets were reconstructed with both charged and neutral particles along with the D⁰-meson for resolution parameters R = 0.2, 0.3, 0.4 within |η_Jet|< 1. - R. The D⁰-jet yields were measured as functions of centrality, and transverse momentum fraction (z) for the first time at RHIC energies. For R = 0.4 jets, the yields are presented in a low p_T, D⁰ interval p_T, D⁰ ∈ [1-5] GeV/c and a high p_T, D⁰ interval p_T, D⁰ ∈ [5-10] GeV/c. The yields are found to be suppressed for hard fragmented jets (z > 0.5) in central Au + Au collisions as compared to peripheral Au + Au collisions, while the yields for soft fragmented jets (z < 0.5) are found to be consistent across centralities in the low p_T, D⁰ interval only. Within the current resolution, no R dependence is observed for the yield suppression in the integrated p_T, D⁰ interval p_T, D⁰ ∈ [1-10] GeV/c. Model calculations including both collisional and radiative energy losses for heavy quarks are shown to qualitatively agree with our measurements except for soft fragmented jets in the low p_T, D⁰ interval.

PRL Figures:

Figure 1:

Fig 1: Top panel: D⁰ meson tagged jet yields as a function of z = p_{T, D⁰}.p_{T, Jet}/|p_{T, Jet}|² for R = 0.4 in AuAu collisions at √s_NN = 200 GeV for central (red circles, scaled by 100), midcentral (green squares, scaled by 10), peripheral (black triangles) in low(left) and high(right) p_{T, D⁰} bins. Middle and Bottom panels: Nuclear modification factors for central (middle) and midcentral (bottom) collisions compared to peripheral collisions.

Figure 2:

Fig 2: D⁰ meson tagged jet yields as a function of z = p_{T, D⁰}.p_{T, Jet}/|p_{T, Jet}|² for R = 0.2 (triangles, scaled by 10⁴), R = 0.3 (square, scaled by 10²), and R = 0.4 (circle, scaled by 1) in AuAu collisions at √s_NN = 200 GeV for central (left panel), midcentral (middle panel), peripheral (right panel).

Figure 3:

Fig 3: Ratio of R_CP as a function of z = p_{T, D⁰}.p_{T, Jet}/|p_{T, Jet}|² for R = 0.4 and R = 0.2 (left panel) and R = 0.4 and R = 0.3 (right panel) in AuAu collisions at √s_NN = 200 GeV.

PRL Conclusions:

•First measurement of transverse momentum fraction (z) for tagged D0 jets at RHIC energies.
•Yields for central suppressed for jets with z > 0.5 as compared to peripheral.
•Yields for central consistent with peripheral for jets with z < 0.5 for low D0 p_T.
•No jet cone size dependence within current resolution. Agreement with models.
•Disagreement with models at low z for low D0 p_T.

PRC Abstract: Centrality and Transverse Momentum Dependence of D⁰ Meson Tagged Charm Jets and D0 Meson Radial Profile in Au + Au Collisions at √s_NN =200 GeV

Measurements of D⁰ meson tagged jets that are reconstructed with anti-k_T sequential algorithm are presented for the first time in  in Au + Au collisions at √s_NN = 200 GeV. The data was collected by the STAR experiment including its Heavy Flavor Tracker - a silicon based detector designed to improve secondary vertex resolution. The D⁰-jet yields are presented as functions of centrality and p_{T, Jet} for 5 < p_{T, Jet} [GeV/c] < 20 and |η_Jet|< 0.6 for R = 0.4 jets in differential p_T,D⁰ bins - [1-5] GeV/c and [5-10] GeV/c. The yield for jets tagged with low p_T D⁰ mesons is found to be consistent across centralities as a function of p_{T, Jet}. Jets tagged with high p_T D⁰ mesons show significant suppression in central compared to peripheral collisions. Within the current uncertainties, the level of jet quenching is found to be consistent across cone sizes R = 0.2, 0.3 and 0.4 for the integrated p_T,D⁰ interval - p_T,D⁰ ∈ [1-10] GeV/c. Furthermore, no modification for radial profile of D⁰ mesons is observed for both low and high p_T D⁰ mesons in R = 0.4 jets. Model calculations that include both collisional and radiative energy losses for heavy quarks qualitatively agree with our measurements.

PRC Figures:

Figure 1:

Fig 1: Invariant mass distribution M_Kπ for 1 < p_T, Kπ < 10 GeV/c for the integrated centrality class 0 - 80 %. Black closed circles represent the invariant mass distribution for unlike sign Kπ pairs. The blue curve is the Gaussian (signal) plus a third order polynomial function (combinatorial background) fitted to the invariant mass distribution using an unbinned extended likelihood method. The signal (background) distribution is shown separately using the green (red) curve.

Figure 2:

Fig 2: p_T,Jet^Det - p_T,Jet^Truth distributions for R = 0.2 (red circles), 0.3 (green squares) and 0.4 (blue triangles) jets in Au + Au collisions in centrality classes 0 - 10 % (left), 10 - 40 % (middle), and 40 - 80 % (right) events.

Figure 3:

Fig 3: Top panel: D⁰ meson tagged jet yields as a function of p_{T, Jet} for R = 0.4 in AuAu collisions at √s_NN = 200 GeV for central (red circles, scaled by 100), midcentral (green squares, scaled by 10), peripheral (black triangles) in low(left) and high(right) p_{T, D⁰} bins. Middle and Bottom panels: Nuclear modification factors for central (middle) and midcentral (bottom) collisions compared to peripheral collisions.

Figure 4:

Fig 4: D⁰ meson tagged jet yields as a function of p_T,Jet for R = 0.2 (triangles, scaled by 10⁴), R = 0.3 (square, scaled by 10²), and R = 0.4 (circle, scaled by 1) in AuAu collisions at √s_NN = 200 GeV for central (left panel), midcentral (middle panel), peripheral (right panel).

Figure 5:

 

Fig 5: Ratio of R_CP as a function of p_T,Jet for R = 0.4 and R = 0.2 (left panel) and R = 0.4 and R = 0.3 (right panel) in AuAu collisions at √s_NN = 200 GeV.

Figure 6:


Fig 6: Top panel: Radial profile of D^₀ mesons in tagged jets for R = 0.4 in AuAu collisions at √s_NN = 200 GeV for central (red circles), midcentral (green squares), peripheral (black triangles) in low(left) and high(right) p_{T, D⁰} bins. Middle and Bottom panels: Ratios of radial profiles for central (middle) and midcentral (bottom) collisions compared to peripheral collisions.

PRC Conclusions:
•No suppression seen for low p_T D⁰ meson tagged jets vs Jet p_T. High p_T D⁰ meson tagged jets show significant suppression vs Jet p_T.
•Radial profile is consistent with no diffusion for both low and high p_T D⁰ mesons. Models agree with radial profile.
•Yield suppression is consistent between jets of different radii. Model predictions agree.

=====================================================================================================================================================================

Figures Not Included:

Integrated p_{T, D⁰} Interval (p_{T, D⁰} ∈ [1-10] GeV/c)

Fig: Top panel: D⁰ meson tagged jet yields as a function of z = p_{T, D⁰}.p_{T, Jet}/|p_{T, Jet}|² (left), p_{T, Jet} (middle), and radial profile of D⁰ mesons in tagged jets for R = 0.4 in AuAu collisions at √s_NN = 200 GeV for central (red circles, scaled by 100), midcentral (green squares, scaled by 10), peripheral (black triangles). Middle and Bottom panels: Nuclear modification factors (left and middle), and ratios of radial profiles (right) for central (middle) and midcentral (bottom) collisions compared to peripheral collisions.