CMS-HIN-21-006 ; CERN-EP-2022-280 | ||
K0S and Λ (¯Λ) two-particle femtoscopic correlations in PbPb collisions at √sNN= 5.02 TeV | ||
CMS Collaboration | ||
13 January 2023 | ||
Phys. Lett. B 857 (2024) 138936 | ||
Abstract: Two-particle correlations are presented for K0S, Λ, and ¯Λ strange hadrons as a function of relative momentum in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The dataset corresponds to an integrated luminosity of 0.607 nb−1 and was collected using the CMS detector at the CERN LHC. These correlations are sensitive to quantum statistics and to final-state interactions between the particles. The source size extracted from the K0SK0S correlations is found to decrease from 4 to 1 fm in going from central to peripheral collisions. Strong interaction scattering parameters (i.e., scattering length and effective range) are determined from the ΛK0S and ΛΛ (including their charge conjugates) correlations using the Lednicky-Lyuboshitz model and are compared to theoretical and other experimental results. | ||
Links: e-print arXiv:2301.05290 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; |
Figures | |
![]() png pdf |
Figure 1:
The invariant mass of K0S (left) and Λ (right), and their corresponding fits in the 0-80% centrality range. The circles are the data, and the fit is shown with a solid (red) line for the total fit, and a dashed (green) line for the background fit. The vertical dashed-dotted (pink) lines indicate the peak region and the vertical dashed (blue) lines indicate the sideband regions. |
![]() png pdf |
Figure 1-a:
The invariant mass of K0S, and the corresponding fit in the 0-80% centrality range. The circles are the data, and the fit is shown with a solid (red) line for the total fit, and a dashed (green) line for the background fit. The vertical dashed-dotted (pink) lines indicate the peak region and the vertical dashed (blue) lines indicate the sideband regions. |
![]() png pdf |
Figure 1-b:
The invariant mass of Λ, and the corresponding fit in the 0-80% centrality range. The circles are the data, and the fit is shown with a solid (red) line for the total fit, and a dashed (green) line for the background fit. The vertical dashed-dotted (pink) lines indicate the peak region and the vertical dashed (blue) lines indicate the sideband regions. |
![]() png pdf |
Figure 2:
The correlation distributions and fits for K0SK0S pairs in different centrality ranges, starting from 0-10% centrality to 50-60% centrality, with 0 <kT< 2.5 GeV. In each plot, the red circles are the data, the blue solid line is the fit using Eq. (8), and the green dotted line is the non-femtoscopic background from Eq. (7). The χ2 and dof values are for the full qinv range. The insert plots show the data and the fit for the qinv< 0.4 GeV region, with the χ2 and number of bins evaluated in that region. |
![]() png pdf |
Figure 3:
The correlation distributions and fits for ΛK0S (left) and ΛΛ (right) pairs with 0-80% centrality and no restriction on kT. In each plot, the red circles are the data, the blue solid line is the fit using Eq. (8), and the green dotted line is the non-femtoscopic background from Eq. (7). The χ2 and dof values are for the full qinv range. The insert plots show the data and the fit for the qinv< 0.4 GeV region, with the χ2 and number of bins evaluated in that region. |
![]() png pdf |
Figure 3-a:
The correlation distributions and fits for ΛK0S ΛΛ pairs with 0-80% centrality and no restriction on kT. The red circles are the data, the blue solid line is the fit using Eq. (8), and the green dotted line is the non-femtoscopic background from Eq. (7). The χ2 and dof values are for the full qinv range. The insert plot shows the data and the fit for the qinv< 0.4 GeV region, with the χ2 and number of bins evaluated in that region. |
![]() png pdf |
Figure 3-b:
The correlation distributions and fits for ΛK0S (left) and ΛΛ (right) pairs with 0-80% centrality and no restriction on kT. In each plot, the red circles are the data, the blue solid line is the fit using Eq. (8), and the green dotted line is the non-femtoscopic background from Eq. (7). The χ2 and dof values are for the full qinv range. The insert plots show the data and the fit for the qinv< 0.4 GeV region, with the χ2 and number of bins evaluated in that region. |
![]() png pdf |
Figure 4:
The Rinv (left) and λ parameter (right) as a function of centrality. For each data point, the line and shaded area indicate the statistical and systematic uncertainty, respectively. |
![]() png pdf |
Figure 4-a:
The Rinv parameter as a function of centrality. For each data point, the line and shaded area indicate the statistical and systematic uncertainty, respectively. |
![]() png pdf |
Figure 4-b:
The λ parameter as a function of centrality. For each data point, the line and shaded area indicate the statistical and systematic uncertainty, respectively. |
![]() png pdf |
Figure 5:
The measured values of d0 versus ℜf0 (left) and ℑf0 versus ℜf0 (right) from this analysis along with other measurements and predictions as described in the text. For each data point, the lines and the boxes indicate the (one-dimensional) statistical and systematic uncertainties, respectively. |
![]() png pdf |
Figure 5-a:
The measured values of d0 versus ℜf0 (left) and ℑf0 versus ℜf0 (right) from this analysis along with other measurements and predictions as described in the text. For each data point, the lines and the boxes indicate the (one-dimensional) statistical and systematic uncertainties, respectively. |
![]() png pdf |
Figure 5-b:
The measured values of d0 versus ℜf0 (left) and ℑf0 versus ℜf0 (right) from this analysis along with other measurements and predictions as described in the text. For each data point, the lines and the boxes indicate the (one-dimensional) statistical and systematic uncertainties, respectively. |
Tables | |
![]() png pdf |
Table 1:
Summary of absolute systematic uncertainties in K0SK0S, ΛK0S and ΛΛ correlation measurements. The values for Rinv, d0, ℜf0, and ℑf0 are in fm. |
![]() png pdf |
Table 2:
Extracted values of the Rinv, ℜf0, ℑf0, d0, λ, and ⟨mT⟩ parameters from the K0SK0S, ΛK0S, and ΛΛ combinations in the 0-80% centrality range. The first and second uncertainties are statistical and systematic, respectively. |
Summary |
The K0SK0S, ΛK0S, and ΛΛ femtoscopic correlations are studied using lead-lead (PbPb) collision data at a center-of-mass energy per nucleon pair of √sNN= 5.02 TeV, collected by the CMS Collaboration. This is the first report on ΛΛ correlations in PbPb collisions at the CERN LHC. The source size Rinv and the incoherence parameter λ were extracted for K0SK0S correlations in six centrality bins covering the 0-60% range. The value of Rinv decreases from 4 to 1 fm going from central to peripheral collisions and agrees with results from the ALICE Collaboration at a similar transverse mass. Along with the Rinv and λ parameters, the strong interaction scattering parameters, i.e.,, the complex scattering length and effective range, were extracted from ΛK0S and ΛΛ correlations in the 0-80% centrality range. These scattering parameters indicate that the ΛK0S interaction is repulsive and that the ΛΛ interaction is attractive. The scattering parameters obtained from ΛK0S correlations differ from those reported by the ALICE Collaboration. The positive real scattering length obtained from the ΛΛ correlation disfavors the existence of a bound H-dibaryon state. The ΛΛ scattering parameters help to constrain baryon-baryon and, more specifically, hyperon-hyperon interaction models. These measurements provide an additional input to understand the nature of the strong interaction between pairs of strange hadrons. |
References | ||||
1 | M. A. Lisa, S. Pratt, R. Soltz, and U. Wiedemann | Femtoscopy in relativistic heavy ion collisions: Two decades of progress | Ann. Rev. Nucl. Part. Sci. 55 (2005) 357 | nucl-ex/0505014 |
2 | V. G. J. Stoks, R. A. M. Klomp, M. C. M. Rentmeester, and J. J. de Swart | Partial-wave analysis of all nucleon-nucleon scattering data below 350 MeV | Phys. Rev. C 48 (1993) 792 | |
3 | J. J. de Swart and C. Dullemond | Effective range theory and the low energy hyperon-nucleon interactions | Anna. Phys. 19 (1962) 458 | |
4 | R. Engelmann, H. Filthuth, V. Hepp, and E. Kluge | Inelastic Σ−p-interactions at low momenta | PL 21 (1966) 587 | |
5 | F. Eisele et al. | Elastic Σ±p scattering at low energies | PLB 37 (1971) 204 | |
6 | B. Sechi-Zorn, B. Kehoe, J. Twitty, and R. A. Burnstein | Low-energy Λ-proton elastic scattering | PR 175 (1968) 1735 | |
7 | CMS Collaboration | Bose--Einstein correlations in pp, pPb, and PbPb collisions at √sNN= 0.9-7 TeV | Phys. Rev. C 97 (2018) 064912 | CMS-FSQ-14-002 1712.07198 |
8 | J. Schaffner-Bielich, M. Hanauske, H. Stöcker, and W. Greiner | Phase transition to hyperon matter in neutron stars | PRL 89 (2002) 171101 | astro-ph/0005490 |
9 | K. Morita, T. Furumoto, and A. Ohnishi | ΛΛ interaction from relativistic heavy-ion collisions | Phys. Rev. C 91 (2015) 024916 | 1408.6682 |
10 | ALICE Collaboration | Study of the Λ-Λ interaction with femtoscopy correlations in pp and pPb collisions at the LHC | PLB 797 (2019) 134822 | 1905.07209 |
11 | R. L. Jaffe | Perhaps a stable dihyperon | PRL 38 (1977) 195 | |
12 | H. Takahashi et al. | Observation of a 6ΛΛHe double hypernucleus | PRL 87 (2001) 212502 | |
13 | K. Nakazawa and H. Takahashi | Experimental study of double-Λ hypernuclei with nuclear emulsion | Prog. Theor. Phys. Supplement 185 (2010) 335 | |
14 | Belle Collaboration | Search for an H-dibaryon with a mass near 2 mΛ in Υ(1S) and Υ(2S) decays | PRL 110 (2013) 222002 | 1302.4028 |
15 | ALICE Collaboration | ΛK femtoscopy in Pb-Pb collisions at √sNN= 2.76 TeV | Phys. Rev. C 103 (2021) 055201 | 2005.11124 |
16 | C. Loizides, J. Kamin, and D. d'Enterria | Improved Monte Carlo Glauber predictions at present and future nuclear colliders | Phys. Rev. C 97 (2018) 054910 | 1710.07098 |
17 | R. Lednicky and V. L. Lyuboshitz | Final state interaction effect on pairing correlations between particles with small relative momenta | Sov. J. Nucl. Phys. 35 (1982) 770 | |
18 | CMS Collaboration | HEPData record for this analysis | link | |
19 | Tracker Group of the CMS Collaboration | The CMS phase-1 pixel detector upgrade | JINST 16 (2021) P02027 | 2012.14304 |
20 | CMS Collaboration | Track impact parameter resolution for the full pseudorapidity coverage in the 2017 dataset with the CMS phase-1 pixel detector | CMS Detector Performance Note CMS-DP-2020-049, 2020 CDS |
|
21 | CMS Collaboration | Performance of the CMS level-1 trigger in proton-proton collisions at √s= 13 TeV | JINST 15 (2020) P10017 | CMS-TRG-17-001 2006.10165 |
22 | CMS Collaboration | The CMS trigger system | JINST 12 (2017) 01020 | CMS-TRG-12-001 1609.02366 |
23 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | |
24 | CMS Collaboration | Precision luminosity measurement in proton-proton collisions at √s= 13 TeV in 2015 and 2016 at CMS | EPJC 81 (2021) 800 | CMS-LUM-17-003 2104.01927 |
25 | CMS Collaboration | CMS luminosity measurement using nucleus-nucleus collisions at √sNN= 5.02 TeV in 2018 | CMS Physics Analysis Summary, 2022 CMS-PAS-LUM-18-001 |
CMS-PAS-LUM-18-001 |
26 | CMS Collaboration | Charged-particle nuclear modification factors in PbPb and pPb collisions at √sNN= 5.02 TeV | JHEP 04 (2017) 039 | CMS-HIN-15-015 1611.01664 |
27 | CMS Collaboration | Description and performance of track and primary-vertex reconstruction with the CMS tracker | JINST 9 (2014) P10009 | CMS-TRK-11-001 1405.6569 |
28 | CMS Collaboration | Transverse-momentum and pseudorapidity distributions of charged hadrons in pp collisions at √s= 0.9 and 2.36 TeV | JHEP 02 (2010) 041 | CMS-QCD-09-010 1002.0621 |
29 | CMS Collaboration | Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon √sNN= 2.76 TeV | Phys. Rev. C 84 (2011) 024906 | CMS-HIN-10-004 1102.1957 |
30 | C. Gale, S. Jeon, and B. Schenke | Hydrodynamic modeling of heavy ion collisions | Int. J. Mod. Phys. A 28 (2013) 1340011 | 1301.5893 |
31 | GEANT4 Collaboration | GEANT 4---a simulation toolkit | NIM A 506 (2003) 250 | |
32 | CMS Collaboration | Strange hadron collectivity in pPb and PbPb collisions | CMS-HIN-19-004 2205.00080 |
|
33 | CMS Collaboration | Strange particle production in pp collisions at √s= 0.9 and 7 TeV | JHEP 05 (2011) 064 | CMS-QCD-10-007 1102.4282 |
34 | CMS Collaboration | Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies | PLB 742 (2015) 200 | CMS-HIN-14-002 1409.3392 |
35 | Particle Data Group Collaboration | Review of particle physics | Prog. Theor. Exp. Phys. 2022 (2022) 083C01 | |
36 | H. Voss, A. Höcker, J. Stelzer, and F. Tegenfeldt | TMVA, the toolkit for multivariate data analysis with ROOT | in XIth International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT), 2007 link |
physics/0703039 |
37 | G. I. Kopylov | Like particle correlations as a tool to study the multiple production mechanism | PLB 50 (1974) 472 | |
38 | A. Kisiel | Non-identical particle correlation analysis in the presence of non-femtoscopic correlations | Acta Phys. Polon. B 48 (2017) 717 | |
39 | ALICE Collaboration | pp, p-Λ, and Λ-Λ correlations studied via femtoscopy in pp reactions at √s= 7 TeV | Phys. Rev. C 99 (2019) 024001 | 1805.12455 |
40 | STAR Collaboration | Neutral kaon interferometry in Au+Au collisions at √sNN= 200 GeV | Phys. Rev. C 74 (2006) 054902 | nucl-ex/0608012 |
41 | A. D. Martin and E. N. Ozmutlu | Analyses of KK production and scalar mesons | NPB 158 (1979) 520 | |
42 | A. Antonelli | Radiative ϕ decays | ConfC 020620 (2002) THAT06 | hep-ex/0209069 |
43 | N. N. Achasov and V. V. Gubin | Analysis of the nature of the ϕ→γπη and ϕ→γπ0π0 decays | PRD 63 (2001) 094007 | hep-ph/0101024 |
44 | N. N. Achasov and A. V. Kiselev | New analysis of the KLOE data on the ϕ→ηπ0γ decay | PRD 68 (2003) 014006 | hep-ph/0212153 |
45 | F. James and M. Roos | Minuit: A system for function minimization and analysis of the parameter errors and correlations | Comput. Phys. Commun. 10 (1975) 343 | |
46 | PHENIX Collaboration | Lévy-stable two-pion Bose--Einstein correlations in √sNN= 200 GeV Au+Au collisions | Phys. Rev. C 97 (2018) 064911 | 1709.05649 |
47 | ALICE Collaboration | One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at √sNN= 2.76 TeV | Phys. Rev. C 92 (2015) 054908 | 1506.07884 |
48 | STAR Collaboration | ΛΛ correlation function in Au+Au collisions at √sNN= 200 GeV | PRL 114 (2015) 022301 | 1408.4360 |
49 | E. Hiyama et al. | Four-body cluster structure of A= 7-10 double-Λ hypernuclei | Phys. Rev. C 66 (2002) 024007 | nucl-th/0204059 |
50 | I. N. Filikhin and A. Gal | Faddeev-Yakubovsky calculations for light ΛΛ hypernuclei | Nucl. Phys. A 707 (2002) 491 | nucl-th/0203036 |
![]() |
Compact Muon Solenoid LHC, CERN |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |