(Anti-)hypertriton lifetime and puzzle

• Introduction • ALICE results • Future perspectives • Summary

Jacek Otwinowski (IFJ PAN, Krakow) On behalf of the ALICE Collaboration Hypernuclei Hypernuclei are bound systems of nucleons and at least one hyperon ( with content)

Hypernuclei measurements: • Properties of baryon-hyperon (N-Y) and hyperon-hyperon (Y-Y) strong and weak interactions in many-body systems • Direct tests of Pauli exclusion principle • Equation of State (EoS) of dense nuclear matter • Modification of hadron properties in dense nuclear matter • Phase transition from hadronic matter to quark-gluon plasma

Theory of N-Y and Y-Y interactions using non-perturbative QCD: • Meson-exchange models (N-Y and Y-Y) • Chiral effective field theory (two and three body interactions) • Lattice QCD (recently big progress, almost physical quark masses) • Constraints from scattering experiments and astrophysical observations (e.g. pulsars, failed supernovea and gravitational waves)

Resent reviews: I. Vidaña, Proc. R. Soc. A 474: 20180145, E. Botta et al. Nuovo Cimento 38 (2015) 387 11-06-2019 SQM2019 - Jacek Otwinowski 2 ~70 years of hypernuclear spectroscopy

• Cosmic rays: photographic emulsions and ~ 1000 hypernuclei measured by now bubble chambers 700 • Discovery of (Pniewski & Proc. R. Soc. A 474: 20180145 Danysz 1952) 600 + + • Strangeness exchange reactions (AGS, CERN, n(π , K )Λ 500 [MeV/c]

BNL, KEK and J-PARC): Λ + - A A - - p(γ, K )Λ • K + Z à �Z + � (K + n à � + �) 400 • Associate production reactions (BNL, KEK, GSI): + A A + + 300 • � + Z à �Z + K (�+ + n à � + K ) • Electroproduction of strangeness on 200 (JLAB, MAMI-C): - - A + A + Momentum Transferred to the n(K , π )Λ • e- + Z à e- + K + �(Z-1) (� + p à � + K ) 100 • Hypernuclei production using stable and 0 unstable ion beams (FAIR/GSI, HypHI): 0 500 1000 1500 2000 Incident Momentum [MeV/c] • 6Li + 12C at 2 AGeV • Hypernuclei production in heavy-ion collisions

• Au+Au at √sNN = 200 GeV (BNL, STAR experiment) - first measurements of anti- nucleus (anti-hypertriton) in heavy-ion collisions, Science 328 (2010) 58

• Pb+Pb at √sNN = 2.76 and 5.02 TeV (CERN, ALICE experiment)

11-06-2019 SQM2019 - Jacek Otwinowski 3 Hypernuclei weak decays

Proc. R. Soc. A 474: 20180145 3 238 U • � Γ Λ Free baryon decays Non-mesonic decay rate NM Total decay rate Γ • �à N + � 2.5 T

209 ΛBi • Hypernuclei decay via mesonic and

free 2 Λ Γ / non-mesonic channels Γ

28 1.5 12 56 ΛSi Fe ΛC Λ 11 • In large hypernuclei mesonic decays 5 ΛB ΛHe Γ T Γ are strongly suppressed by the Pauli 1 1 Weak decay rate Γ principle (pN < Fermi momentum) NM • � N à N + N 0.5 Γ Γ • � N Nà N + N + N M 2

0 10 100 Total number of particles A+1

11-06-2019 SQM2019 - Jacek Otwinowski 4 Discovery of hypernucleus

M. Danysz and J. Pniewski, Phil. Mag. 44 (1953) 348

• The first observation of an hypernucleus (or more precisely an hyperfragment) • Events recorded by a stack of photographic emulsions exposed to the cosmic radiation at about 26 km from the Earth surface in a balloon • Hypernuclear species were unambiguously identified by the kinematic analysis of the disintegration star

• Photographic emulsion experiments provide extremely precise measurements of � binding energy B� in nuclei (reference as of today)

11-06-2019 SQM2019 - Jacek Otwinowski 5 Hyperon puzzle 450 2.5 Proc. R. Soc. A 474: 20180145 400 nucleons & leptons PSR J0348+0432 nucleons, & leptons 2 ) 350 -3 PSR J1614-2230 300 1.5 (solar mass units)

250 Hulse-Taylor PSR G 200 1 150

Pressure P (MeV fm 100 0.5 (a) 50 (b)

0 0 Gravitational mass M 0 200 400 600 800 1000 1200 0 0.5 1 1.5 -3 -3 Energy density ε (MeV fm ) Central baryon number density ρ (fm )

• Hyperons may appear in the inner core of stars at densities of about 2−3ρ0 • Their presence in the neutron star interior leads to a softening of the EoS and consequently to a reduction of the maximum mass (current predictions 1.4-1.8 M⨀) • Astrophysical observations of pulsars rule out almost all currently proposed EoS with hyperons…? • Additional repulsion: Y-Y repulsive potential, hyperonic three-body forces (e.g. NNY, NYY, YYY), quark-gluon plasma below the hyperon threshold (hybrid neutron stars)…?

11-06-2019 SQM2019 - Jacek Otwinowski 6 (ANTI-)HYPERTRITON LIFETIME MEASUREMENT IN PB+PB COLLISIONS WITH ALICE

11-06-2019 SQM2019 - Jacek Otwinowski 7 A Large Ion Collider Experiment

• Excellent particle identification capabilities over a wide pT range 0.1-20 GeV/c • Good momentum resolution ~1-5% for pT = 0.1-50 GeV/c

Central barrel tracking and PID |η|< 0.9 Centrality V0A 2.8 < η < 5.1 V0C −3.7 < η < −1.7

MUON arm - 4.0 < η < -2.5 y x z 11-06-2019 SQM2019 - Jacek Otwinowski 8 ALICE at work since 2009

System Year √sNN (TeV) Lint Pb-Pb 2010-2011 2.76 ~75 μb-1 2015 5.02 ~250 μb-1 2018 5.02 ~0.9 nb-1 Xe-Xe 2017 5.44 ~0.3 μb-1 pp p-Pb 2013 5.02 ~15 nb-1 2016 5.02, 8.16 ~3 nb-1, ~25 nb-1 pp 2009-2013 0.9, 2.76, ~200 μb-1, ~100 μb-1, 7, 8 ~1.5 pb-1, ~2.5 pb-1 2015-2018 5.02, 13 ~1.3 pb-1 , ~59 pb-1 p-Pb • Energy and system dependence studies of particle production are possible • Large statistics of pp, p-Pb and Pb-Pb collisions at the

same √sNN • Analysis of 2018 Pb-Pb data is not completed yet

Pb-Pb

11-06-2019 SQM2019 - Jacek Otwinowski 9 ALICE case

Enhanced hyperon production Similar amount of and antibaryons

1.1 pp at s = 2.76 TeV Pb-Pb at sNN = 2.76 TeV, 0-80 % DPMJet prediction /B p/p: |y |<0.5, 0.45 < p < 1.05 GeV/c |y |<0.5, 0.45 < p < 1.05 GeV/c T T Pb-Pb at sNN = 2.76 TeV B Λ/Λ: |y |<0.8, 0.5 < p < 4.5 GeV/c |y |<0.6, 0.5 < p < 4.5 GeV/c + T p-Pb at s = 5.02 TeV 1.08 Ξ /Ξ-: |y |<0.8, 0.5 < pT < 4.5 GeV/c |y |<0.6, 0.5 < p < 5.5 GeV/c NN + T T Ω /Ω-: |y |<0.8, 1.0 < p < 5.5 GeV/c |y |<0.6, 1.0 < p < 4.5 GeV/c 1.06 T T p-Pb at sNN = 5.02 TeV, Min. Bias pp at s = 7 TeV p/p: -0.965 < y < 0.035, 0.45 < p < 1.05 GeV/c |y |<0.5, 0.45 < p < 1.05 GeV/c T T 1.04 Λ/Λ: -1.265 < y < 0.335, 0.5 < p < 10.5 GeV/c |y |<0.8, 0.5 < p < 10.5 GeV/c + T T Ξ /Ξ-: -1.265 < y < 0.335, 0.5 < p < 6.0 GeV/c |y |<0.8, 0.5 < p < 5.5 GeV/c + T T Ω /Ω-:-1.265 < y < 0.335, 1.0 < p < 5.5 GeV/c |y |<0.8, 1.0 < p < 5.5 GeV/c 1.02 T T 1 0.98 0.96

0.94 ALICE 0.92 preliminary

+ - + - ALI−PREL−72168 p/p Λ/Λ Ξ /Ξ Ω /Ω

à ALICE is well suited for (anti-)hypernuclei measurements pp 7 TeV: Nature Physics 13 (2017) 535 p-Pb 5.02 TeV: Phys. Lett. B728 (2014) 25, Phys. Lett. B758 (2016) 389

11-06-2019 SQM2019 - Jacek Otwinowski 10 (Anti-)hypertriton

3 Hypertriton ( �H) is the lightest known hypernucleous (p, n, �), anti- � hypertiton ( ) �H

• Mass ~ 2.992 GeV/c2 - D.H. Davis Nucl. Phys. A 754 (2006) 3

• Binding energy B� ~ 0.13 MeV (Bd = 2.2 MeV, Bt = 8.5 MeV, B3He = 7.7 MeV) • Unstable under weak decay (branching ratios are not well known; only few theoretical calculations available - H. Kamada et al. Phys. Rev. C 57 (1998) 1595) • Mesonic and non-mesonic decays

• ALICE studied production of hypertriton in the charged mesonic decay channels • 2 body (B.R. ~ 25%) • 3 body (B.R. ~ 41%) • Only 2 body decay channel has been used for the lifetime measurements

11-06-2019 SQM2019 - Jacek Otwinowski 11 (radial (Antiflow) -)hypertriton signal extraction

3 3 - �H à He + �

• Identify products of weak decay (3He, �-) • Specific energy loss in the TPC detector • For deuteron identification also TOF information • Apply topological cuts • Secondary decay vertex reconstruction • Reduction of combinatorial background • Reconstruct invariant mass

11-06-2019 SQM2019 - Jacek Otwinowski 12 (radial (Antiflow) -)hypertriton signal extraction ) 2 c 140 ALICE Performance, 28/11/2016

s = 5.02 TeV 120 NN Pb−Pb, 0−80%

100 |y| < 0.9 Counts / (2 MeV/

80

60 ) 2

c 220 ALICE Performance 40 Data 200 − s Fit Pb Pb NN = 2.76 TeV (2011) 180 Background 20 0-10%, |y| < 0.5 160 0 Entries / (2 MeV/ 140 2.97 2.98 2.99 3 3.01 3.02 3.03 3.04 3.05 M( 3He, π-& 3He, π+) (GeV/c2) 120 ALI-PERF-114838

100 80 Corrections: 60 3 → π+ ΛH d + p + 40 • Detector acceptance and 20 reconstruction efficiency 0 2.96 2.97 2.98 2.99 3 3.01 3.02 3.03 3.04 3.05 • Absorption of (anti-)hypertiton 2 M + (GeV/c ) ALI-PERF-129924 d,p,π in detector material

11-06-2019 SQM2019 - Jacek Otwinowski 13 Hypernuclei yields vs thermal models in (radial flow) Pb-Pb at √sNN = 5.02 TeV

• Production of (most) hadrons well described at freeze-out

temperature Tch ~ 153 MeV

• Light nuclei production Pb-Pb (0-10%) 5.02 TeV described by thermal models

(binding energy << Tch)?

• Other production processes e.g. via coalescence are also considered

THERMUS: Wheaton et al., Comput. Phys. Commun, 180 (2009) 84 GSI-Heidelberg: Andronic et al., Phys. Lett. B 673 142 SHARE: Petran et al., Comp. Phys. Commun. 195 (2014) 2056

11-06-2019 SQM2019 - Jacek Otwinowski 14 (radial flow) (Anti-)hypertriton lifetime Invariant mass determined in four c� intervals 3 3 - �H à He + �

) ) 90 2 2

c 120 c ALICE Data 80 Signal + background 100 Pb-Pb s = 5.02 TeV NN 70 0-90%, |y | < 0.8 Background 60 80 Events / (2 MeV/ Events / (2 MeV/ 50 60 40

40 30

20 20 4 £ ct < 7 cm 10 7 £ ct < 10 cm 2.97� 2.98= 2.99�� 3 3.01 3.02 3.03 3.04 3.05 2.97 2.98 2.99 3 3.01 3.02 3.03 3.04 3.05 Invariant mass ( 3He+p- + 3He+p+) (GeV/c2) Invariant mass ( 3He+p- + 3He+p+) (GeV/c2)

) 90 ) 2 2 c c c � M L c/p 100 = 80

70 2 80 M = 2.99116 ± 0.0005 GeV/c 60 Events / (2 MeV/ Events / (2 MeV/ L - decay length 50 60 40 p - hypertriton momentum 40 30

20 20 Mass calculated with 10 10 £ ct < 15 cm 15 £ ct < 28 cm

2.97 2.98 2.99 3 3.01 3.02 3.03 3.04 3.05 2.97 2.98 2.99 3 3.01 3.02 3.03 3.04 3.05 B = 0.13 ± 0.05 MeV 3 3 3 3 � Invariant mass ( He+p- + He+p+) (GeV/c2) Invariant mass ( He+p- + He+p+) (GeV/c2) ALICE, arXiv:1907.06906 11-06-2019 SQM2019 - Jacek Otwinowski 15 (radial flow) (Anti-)hypertriton lifetime ALICE, arXiv:1907.06906 3 H à 3He + �- � Corrected yields in four ct intervals vs ct ) -1 102 ALICE (cm )

N ct Pb-Pb s = 5.02 TeV d NN d( 0-90%, |y | < 0.8

3 H + 3 H L L

Data Systematic uncertainty

10 Exponential fit c � = M L c/p

ct = 7.25+1.02 (stat.) ± 0.51 (syst.) (cm) M = 2.99116 ± 0.0005 GeV/c2 -1.13

L - decay length 5 10 15 20 25 p - hypertriton momentum ct (cm)

Mass calculated with Lifetime from exponential fit: B� = 0.13 ± 0.05 MeV � = 242 stat. ± 17 (syst. ) ps

11-06-2019 SQM2019 - Jacek Otwinowski 16 (radial flow) (Anti-)hypertriton lifetime ALICE, arXiv:1907.06906 Crosscheck method: unbinned maximum-likelihood fit to the c � distribution in the signal region

) 1 t (

l ALICE 0.9

log 0-90% Pb-Pb sNN = 5.02 TeV - 0.8 3 H + 3 H L L

0.7 +40 t = 240 -31 (stat.) ± 23 (syst.) ps 0.6

0.5

0.4

0.3

0.2

0.1

0 180 200 220 240 260 280 300 320 Lifetime t (ps)

Probability density function used in the c � fit is the sum of two exponentials (background) Lifetime from the unbinned fit: and product of exponential plus efficiency � = 240 stat. ± 23 (syst. ) ps parametrization for the signal.

11-06-2019 SQM2019 - Jacek Otwinowski 17 (radial flow)(Anti-)hypertriton lifetime puzzle ALICE, arXiv:1907.06906

500 Theoretical prediction L lifetime - PDG value H. Kamada et al., PRC 57 (1998) 1595 3 LH average lifetime R.H. Dalitz, M. Rayet, Nuo. Cim. 46 (1966) 786

J. G. Congleton, J. Phys G Nucl. Part. Phys. 18 (1992) 339 400 �avr = 206 ps A. Gal, H. Garcilazo, PLB 791 (2019) 48-53 Lifetime (ps)

300 HypHI ALICE

200 PRL 20 (1968) 819 PRD 1 (1970) 66 ALICE PR 180 (1969) 1307 NPB 67 (1973) 269 Pb-Pb 5.02 TeV

NPA 913 (2013) 170 Science 328 (2010) 58 PLB 754 (2016) 360 100 PRC 97 (2018) 054909 NPB 16 (1970) 46

PR 136 (1964) B1803 STAR 0

• Shorter lifetime of (anti-)hipertriton as compared to free � hyperon • Recent ALICE results in agreement with the average value and with theory predictions • Recent STAR results including 3 body decay channel show very low value

11-06-2019 SQM2019 - Jacek Otwinowski 18 Hypernuclei lifetimes E. Botta et al. Nuovo Cimento 38 (2015) 387 Models: • �avr = 216 ps (up to 2015) �avr = 206 ps (up to 2019) K. Itonaga et al. Nucl. Phys. A, 639 (1998) 329c • One pion exchange approach • E. Bauer et al. Phys. Rev. C 81 (2010) 064315 • 2 nucleon non-mesonic weak decays • K. Itonaga et al. Prog. Theor. Phys. Suppl., 185 (2010) 252 • One-pion exchange with addition of many exchange terms

• A big decrease of (anti-)hypertriton lifetime as compared to 2015 value • heavy = weighted average of lifetimes of nuclei with 180 < A < 238

11-06-2019 SQM2019 - Jacek Otwinowski 19 (radial(Anti flow)-)hypertriton binding energy at RHIC STAR, arXiv:1904.1052

1.0 1.0 Values with recalibration Theoretical calculation 0.8 0.8 (MeV) (MeV) 2 2 3 3 3 3 ΛH + ΛH ΛH + ΛH )c 0.6 3 )c 0.6 3 ΛH ΛH H H 3 Λ 3 Λ

0.4 0.4 PRL89(2002) 3 H 3 H Λ arXiv: Λ - m - m 1711.07521 Λ Λ 0.2 0.2 PRC77(2008) NPB4(1968) STAR (2019) STAR (2019)

+ m + m NPB47(1972) d 0.0 NPB1(1967) NPB52(1973) d 0.0

−0.2 −0.2 = (m = (m Λ Λ B B −0.4 PRD1(1970) −0.4

• STAR measured B� which differs (~2.6�) from the widely used value (B� ~ 0.13 MeV) • Measurements are performed in the (anti-)hypertriton 2 and 3 body decay channels: (3He, �) and (d, p, �) • Recalibrated values are with updated masses from CODATA and PDG • Large spread of theoretical predictions à Precise data are required!

11-06-2019 SQM2019 - Jacek Otwinowski 20 (radial flow)Hypernuclei - future perspectives

• L = 10/nb Pb+Pb statistics is ALICE Upgrade projection expected in ALICE during LHC Run-3 Pb-Pb, sNN = 5.5 TeV (0-10%), B=0.5 T 3 H ® 3He + p+ L (2021-2023) and Run-4 (2024-2028) B.R. = 25% (*) � 2 4 H ® 4He + p+ • Above 3� significance for He 10 L � B.R. = 50% (*) 4 He ® 3He + p + p+ L B.R. = 32% (*) • Further experiments are planned in (*) theoretical the future at BNL, KEK and J-PARC

Expected significance 10 5s with K− beams, and at FAIR/GSI with 3s protons and

1

10-2 10-1 1 10 Min. bias integrated luminosity (nb-1)

ALI−SIMUL−312332

11-06-2019 SQM2019 - Jacek Otwinowski 21 Summary

• ALICE has measured (anti-)hypertriton lifetime in Pb+Pb collisions at √sNN = 2.76 TeV and 5.02 TeV � = 181 stat. ± 33 (syst. ) ps � = 242 stat. ± 17 (syst. ) ps • Obtained results are in agreement with the current World average �avr = 206 ps (up to 2019) • Shorter lifetime of (anti-)hipertriton as compared to free � hyperon

• Recent STAR results in Au+Au collisions at at √sNN = 200 GeV (including 3 body decay channel) show very low value as compared to the free � hyperon lifetime � = 142 stat. ± 29 (syst. ) ps

• STAR measured B� which differs (~2.6�) from the widely used value (B� ~ 0.13 MeV) • Larger statistics and better quality data are expected in the future at CERN, BNL, KEK and J-PARC, and at FAIR/GSI

11-06-2019 SQM2019 - Jacek Otwinowski 22 Backup

11-06-2019 SQM2019 - Jacek Otwinowski 23 Stages of the relativistic heavy-ion collision

Bjorken 1983

Chemical and thermal freeze-out

Hadronization (T ~ TC)

Quark-Gluon Plasma (thermalized matter?)

Pre-equilibrium, fast thermalization ~ 1 fm/c, glasma?

Hard collisions

Lorentz-contracted ions (dense gluonic matter, Color Glass Condensate?) • All stages in models of nuclear collisions • QGP expansion modeled by relativistic hydrodynamics

11-06-2019 SQM2019 - Jacek Otwinowski 24 Event Centrality Selection ALICE-PUBLIC-2018-011

b

• Correlate particle multiplicity with collision geometry i.e. impact parameter, volume and shape (A. Białas et al. APPB 8 (1977) 389) NN • Ncoll, Npart and TAA = Ncoll / σ INEL values determined by fitting NBD-Glauber coupled to two parameter model

11-06-2019 SQM2019 - Jacek Otwinowski 25 (radialAnti f -particles production in Pb+Pb at 5 TeV

11-06-2019 SQM2019 - Jacek Otwinowski 26 Particle yields vs thermal models in (radial flow) Pb-Pb at √sNN = 2.76 TeV Nucl. Phys. A 971 (2018) 1 • Production of (most) hadrons well described at freezeout

temperature Tch ~ 156 MeV • K*0 resonance (not included in the fit): production Pb-Pb (0-10%) 2.76 TeV overestimated by thermal models • Tension for protons and multi-strange baryons • Light nuclei production described by thermal models

(binding energy << Tch)?

THERMUS: Wheaton et al., Comput. Phys. Commun, 180 (2009) 84 GSI-Heidelberg: Andronic et al., Phys. Lett. B 673 142 SHARE: Petran et al., Comp. Phys. Commun. 195 (2014) 2056

11-06-2019 SQM2019 - Jacek Otwinowski 27 Nuclei production in pp, p-Pb and Pb-Pb p-Pb: arXiv:1906.03136

2 10 p ALICE √sNN = 2.76 TeV s Hagedorn resonance gas 1.8 STAR Au-Au NN = 200 GeV 10 Ratio Science 328 (2010) 58 THERMUS

/ (2J + 1) 1 1.6 ALICE Pb-Pb s = 2.76 TeV GSI-Heidelberg y -1 NN d PLB 754 (2016) 360 /d 10 1.4 SHARE N -2 ALICE Preliminary

d 10 Pb-Pb s = 5.02 TeV -3 3 1.2 NN 10 He ( 3 H + 3 )H Λ Λ -4 3 3 10 1 3 3 ( He + He) -5 4 H + H 10 New He 0.8 Λ Λ assuming B.R. = 25% -6 3 10 3 0-10% Pb-Pb, s = 2.76 TeV 0.6 He + He 10-7 NN -8 NSD p-Pb, s = 5.02 TeV 0.4 10 NN -9 10 INEL pp, s = 7 TeV 0.2 Uncertainties: stat. (bars), sys. (boxes) 10-10 0 1 2 3 4 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 A 〈dN / dη 〉 ALI−PREL−146723 ch lab |η | < 0.5 lab • Exponential decrease in nuclei rate in agreement with thermal model predictions • Nuclei production rate decrease by factor of ~300 (Pb-Pb), ~600 (p-Pb) and ~1000 (pp) for each additional nucleon 3 • ΛH production consistent with thermal model (binding energy ~0.13 MeV << Tch) à Production mechanisms: thermal vs coalescence? pp: Phys. Rev. C97 (2018) 024615 Pb-Pb: Nucl. Phys. A 971 (2018) 1 11-06-2019 SQM2019 - Jacek Otwinowski 28 Formation of light nuclei: (anti) deuterons

• Coalescence of baryons close in phase space (A - mass number)

• B2 shows dependence on multiplicity (no dependence on pT)

• d/p vs multiplicity • Increase from pp to peripheral Pb-Pb consistent with coalescence model • No centrality dependence in high multiplicity Pb-Pb (yields consistent with thermal model) à Production mechanisms: thermal vs coalescence?

11-06-2019 SQM2019 - Jacek Otwinowski 29 (radial(Anti flow)-)hypertriton production vs. models • Hybrid UrQMD, combines the hadronic transport approach with SHARE B.R. ALICE Preliminary hydrodynamical evolution ×

y GSI-Heidelberg Pb−Pb s = 5.02 TeV /d NN J.Steinheimer at al. Phys. Lett B 714

N Hybrid UrQMD d 0−10% centrality (2012) 85

• GSI-Heidelberg: equilibrium thermal −4 10 3 3 ΛH + ΛH model; particle production at 2 freezeout temperature Tch~ 156 MeV Andronic et al., Phys. Lett. B 673 142

• SHARE: non-equilibrium thermal

model, Tch ~ 140 MeV, Petran et al., Comp. Phys. Commun. 195 (2014) 0.15 0.2 0.25 0.3 0.35 2056 ALI−PREL−146719 B.R.

• Light nuclei production described by thermal models (binding energy << Tch)? • Production via coalescence is considered

11-06-2019 SQM2019 - Jacek Otwinowski 30