Strange Exotic States and Compact Stars
Irina Sagert, Mirjam Wietoska, Ju rgen Schaffner–Bielich
Institute for Theoretical Physics/Astrophysics
International Conference on Strangeness in Quark Matter University of California, Los Angeles, USA, March 26–31, 2006
J. Schaffner-Bielich, Goethe University, Frankfurt – p.1/27 Outline
Multi-quark states and neutron stars Light pentaquarks with strangeness Heavy pentaquarks and multi-quark states with charm Pentaquarks in the medium and in neutron stars Constraints for pentaquarks from pulsar mass measurements Signals for strange quark matter in compact stars pulsar kicks gamma-ray bursts gravitational waves Summary
J. Schaffner-Bielich, Goethe University, Frankfurt – p.2/27 Multi–Quark States and Neutron Stars
J. Schaffner-Bielich, Goethe University, Frankfurt – p.3/27 Multi-Quark States: Some History (incomplete)
multi-quark states already mentioned by Gell-Mann in 1964 strange four-quark states (qsq¯s):¯ Jaffe 1977 strange six-quark states (qqqqss: H-dibaryon): Jaffe 1978 heavy tetraquarks (QQq¯q):¯ Ader, Richard, Taxil 1982 pentaquarks with charm (qqqsc):¯ Lipkin 1987 and Gignoux, Silvestre-Brac, Richard 1987 . . . light pentaquark (qqqqs)¯ in chiral soliton model: Diakonov, Petrov, Polyakov 1997 light pentaquark in diquark model: Jaffe and Wilczek 2003
J. Schaffner-Bielich, Goethe University, Frankfurt – p.4/27 Pentaquark/Multiquark candidates
+ light pentaquark antidecuplet detection of pentaquark first reported in 2003 mass 1.54 GeV, small width (<1 MeV) experimental situation for + today: conflicting! (PDG status 2005 down to **) but not hopeless =⇒ talk by Nakano!
++ seen by STAR in dAu data? (not in pp, AuAu) H dibaryon signal seen by STAR? (PhD thesis of Renaud Vernet)! NA49 reports on (1860) pentaquark (ssddu)¯
charmed pentaquark c(3100) (uuddc)¯ reported by H1 collaboration
J. Schaffner-Bielich, Goethe University, Frankfurt – p.5/27 Multi-quark states with charm: charmlets
(JSB and A. Vischer, PRD 57 (1998) 4142)
40 1e−01
1e−02 C=2 20 1e−03 C=3 ms C=4 1e−04 C=5 [MeV] c 0 m
c 1e−05 −f N B1/4=145 MeV 1e−06
)m −20 c 1e−07 α =0.0 c Number per event 1e−08 −40 α m =1.5 GeV c=0.1 c
E/A−(3−f α c=0.3 ms=150 MeV 1e−09
−60 1e−10 0.0 1.0 2.0 3.0 0.00 0.10 0.20 0.30 fc p0 [GeV]
unified bag model for light (color-magnetic potential) and heavy quarks (color-electric potential) shell-model calculation: hexaquark candidates {cssuud}+, {cssudd}0, {ccsuud}++, {ccsuud}+, {ccssud}+ production rates at RHIC: 10 3 to 10 2 per event direct charm measurements with future micro-vertex detectors! J. Schaffner-Bielich, Goethe University, Frankfurt – p.6/27 Pentaquarks in the medium: + hyponuclei?
Quark Model: stable + in nuclei! critical potential: U( +) < 105 MeV (Miller 2004) RMF model: U( +) = 50 to 90 MeV (Zhong, Tan, Peng, Li, Ning 2005) QCD sum rules: U( +) = 40 to 90 MeV (Navarra, Nielsen, Tsushima 2005) Hadronic SU(3) approach: U( +) = 60 to 120 MeV (Cabrera, Li, Magas, Oset, Vicente Vacas 2005) Quark mean-field model: U( +) 50 MeV (Shen and Toki 2005)
Note: + can explain long-standing puzzle (missing reactivity) in K+-nucleus reactions! (Gal and Friedmann 2005, Tolos, Cabrera,
Ramos, Polls 2006) J. Schaffner-Bielich, Goethe University, Frankfurt – p.7/27 Pentaquarks in dense matter: neutron stars
inverse mass-radius plot (gm1) 2.5 n,p,e 2 H -40 MeV 1.5 -100 MeV -250 MeV 1
0.5 Mass [solar mass units]
0 8 10 12 14 16 18 20 Radius [km]
(=⇒ see poster by Mirjam Wietoska)
maximum mass of neutron stars: > 2M for nucleons plus leptons only
reduced by hyperons to M < 2M even further reduced by pentaquarks! maximum mass sensitive to + potential!
J. Schaffner-Bielich, Goethe University, Frankfurt – p.8/27 Composition of neutron stars with pentaquarks
Θ+ potential depth=-100 [Mev] (gm1) 1 n p e- 0.1 µ- Λ Ξ- 0.01 Ξ0 Θ+ ρ c 0.001 0 2 4 6 8 10 ρ number density [ 0]
(M. Wietoska, JSB, 2006)
hyperons appear around 2n0 + + appear around 4n0 (for U( ) = 100 MeV at n0) for the maximum mass star: about 5% + in the core J. Schaffner-Bielich, Goethe University, Frankfurt – p.9/27 Maximum mass for + neutron stars
Θ+ 2 gm1 1.9 tm1 1.8 tm2 nl3 1.7 1.44 Msun 1.6 1.60 Msun
1.5
1.4
maximum mass [solar mass units] 1.3 -300 -240 -180 -120 -60 0 60 potential depth [MeV]
(M. Wietoska, JSB, 2006)
+ can appear even for U( +) = +50 MeV ! + for M > 1.6M , the potential depth U( ) > 190 MeV ⇒ weak constraint on + potential pulsar mass measurements =⇒ talk by Ingrid Stairs!
J. Schaffner-Bielich, Goethe University, Frankfurt – p.10/27 Pulsar Mass Constraints for in matter
Θ- 1.9 gm1 1.8 tm1 1.7 tm2 1.6 nl3 1.44 M 1.5 sun 1.60 Msun 1.4 1.3 1.2
maximum mass [solar mass units] 1.1 -100 -60 -20 20 potential depth [MeV]
(M. Wietoska, JSB, 2006)
for M > 1.44M : potential depth U( ) > 55 . . . 125 MeV ! for M > 1.6M : potential depth U( ) > 0 . . . 85 MeV ⇒ strong constraint on potential J. Schaffner-Bielich, Goethe University, Frankfurt – p.11/27 Signals for Strange Quark Matter in Compact Stars
J. Schaffner-Bielich, Goethe University, Frankfurt – p.12/27 Hunting down strange quark matter in the heavens
Coming of age! Some recently suggested signals:
’exotic’ mass-radius relation of compact stars enhanced cooling of neutron stars gamma-ray bursts by transition to strange quark matter gravitational wave signals of collisions of compact stars with quark matter (3D in General Relativity) pulsar kicks by asymmetric emission of neutrinos from quarks: check for the energetics (enough kick?) check for the anisotropy (enough polarization?) check for the neutrino rocket (do they come out?) =⇒ see poster by Irina Sagert
J. Schaffner-Bielich, Goethe University, Frankfurt – p.13/27 Pulsar kicks: speeding neutron stars!
Crab pulsar Vela pulsar
pulsars moving out of the center of the supernova remnant high space velocities observed: up to 1600 km/s ! (Hobbs 2005) highest directly measured kick velocity: 1080 100 km/s (Chatterjee et al. 2005) kick axis closely aligned with rotational axis (Crab, Vela, B0656+14)
J. Schaffner-Bielich, Goethe University, Frankfurt – p.14/27 Supernovae and proto-neutron stars (Lattimer and Prakash 2004)
energy stored in neutrinos: 99% of total supernova energy! kinetic energy of pulsar kick: 1% of energy stored in neutrinos asymmetry of 1% for neutrino emission sufficient for kick! J. Schaffner-Bielich, Goethe University, Frankfurt – p.15/27 Pulsar kicks by asymmetric neutrino emission
20
15
10 R [km] 1000 km/s
5
100 km/s α µ χ = 1 s = 0.5, q = 400 MeV, Mns=1.4 Msun, 0 1 2 3 4 5 6 7 8 9 10 T [1010K] (Sagert, JSB, 2006)
electron capture on quarks: parity-violating → anisotropic production of neutrinos for degenerate matter! → need just about T = 5 MeV for sufficient pulsar kick J. Schaffner-Bielich, Goethe University, Frankfurt – p.16/27 Polarization by ultrastrong magnetic fields
1e+11 B=5*1017G 17 9e+10 B=2*10 G B=1017G B=5*1016G 8e+10 B=1016G 7e+10
6e+10
T [K] 5e+10
4e+10
3e+10
2e+10
1e+10 0 10 20 30 40 50 60 70 80 µ e [MeV] (Sagert, JSB, 2006)
surface magnetic fields of pulsars: typically B ' 1012 Gauss magnetars: up to 1015 Gauss! magnetic field in (quark) core: up to 1018 Gauss possible electrons in strong magnetic fields: moving in Landau levels lowest Landau level: fully polarized! J. Schaffner-Bielich, Goethe University, Frankfurt – p.17/27 Mean-free paths of neutrinos in dense and hot matter
(Reddy, Sadzikowski, Tachibana 2003)
phase process (T=5 MeV) (T=30 MeV) Nuclear n → n 200 m 1 cm Matter en → e p 2 m 4 cm Unpaired q → q 350 m 1.6 m Quarks d → e u 120 m 4 m CFL → H 100 m 70 cm → >10 km 4 m
small mean-free path in nuclear matter larger mean-free path in quark matter color-flavor locked phase: in principle huge mean-free path massless excitation (H): mean-free path similar to normal quark matter! size of coupling strength of H well determined! (thanks Sanjay!)
J. Schaffner-Bielich, Goethe University, Frankfurt – p.18/27 Mean-free path of neutrinos and kick velocity
20 neutron star velocity lq ln
15
10 R [km] 1000 km/s
5
100 km/s
0 1 2 3 4 5 6 7 8 9 10 T [1010K] (Sagert, JSB, 2006)
problem: neutrinos have to get out without rescattering to preserve anisotropy mean-free path too short at T = 5 MeV!
J. Schaffner-Bielich, Goethe University, Frankfurt – p.19/27 Pulsar kicks for color superconducting quark matter
µ µ ∆ e = 100 MeV, q = 400 MeV, =100 MeV 20 neutron star velocity lq
15
10 R [km]
5
0 5 10 15 20 25 30 35 40 45 50 T [1010K] (Sagert, JSB, 2006)
increase mean-free path exponentially with gap: exp( /T ) but thermal energy (specific heat) decreases exponentially, too! both curves (kick velocity and mean-free path) are shifted up =⇒ need some mechanism to increase specific heat of color superconducting quark matter (Goldstone modes?) J. Schaffner-Bielich, Goethe University, Frankfurt – p.20/27 Gamma-ray bursters
highly energetic events in the sky energy release similar to supernova energies! about one gamma-ray burst per day! sources: colliding neutron stars, stars collapsing to black holes or collapsing compact stars! J. Schaffner-Bielich, Goethe University, Frankfurt – p.21/27 Signal from quiescent gamma-ray bursters?
(Pagliara, Drago 2006) 1600
1400
D 1200 #5486 ms
64 1000 55-320 keV
800 per @ 600
400 Counts 200 4Σ 2Σ 140 160 180 200 220 t s
subsample with long quiescent periods @(>40D s) extracted (BATSE catalog) similar characteristics of the bursts before and after quiescence points to a dormant inner engine (not related to pulsar wind)! hints at a collapse of a neutron star with two phase transitions: first to quark matter then to color–superconducting matter!?!
J. Schaffner-Bielich, Goethe University, Frankfurt – p.22/27 Summary
charming multiquark states: do not miss to look for it! light pentaquark states can be present in neutron star cores light pentaquark in-medium properties can be constrained by pulsar mass measurements strange quark matter can signal itself in astrophysical observables high-velocity pulsars observed (pulsar kicks): relation to formation of strange quark matter in core? gamma-ray bursts with long quiescence times: phase transitions to normal then to color-superconducting quark matter? much more astro data on the horizon, a lot of opportunities → cross-talk with observers needed!!!
J. Schaffner-Bielich, Goethe University, Frankfurt – p.23/27 Composition of neutron stars with
Θ- potential depth=-100 [MeV] (gm1) 1 n p e- 0.1 µ- Λ Θ- ρ 0.01 c
0.001 0 2 4 6 8 10 ρ number density [ 0]
(M. Wietoska, JSB, 2006)
(hypothetical) negatively charged appears at 2n0 present as first exotic/strange component!
maximum density only 3.3n0 J. Schaffner-Bielich, Goethe University, Frankfurt – p.24/27 < 1.60 Msun
> 1.60 Msun
Pulsar Mass Constraints for in matter
Ξ-- with 1.60 Msun 0 gm1 -50 tm1 -100 tm2 nl3 -150
-200
-250 Potential depth [MeV] -300
-350 1440 1520 1600 1680 1760 1840 Mass of Ξ-- [MeV]
(M. Wietoska, JSB, 2006)
Pentaquark : only small masses and strongly attractive potentials are incompatible with pulsar mass measurements
J. Schaffner-Bielich, Goethe University, Frankfurt – p.25/27 Pulsar kick explanations
deformed neutrino-sphere in magnetic fields, emission of sterile neutrinos (Kusenko, Segre, 1997) needs exotic particles (sterile neutrinos)! parity-violating neutrino emission in strong magnetic fields in nuclear matter (Li, Horowitz 1998) only surface emission, needs large magnetic fields at surface! spin–1 color superconductivity (Schmitt, Shovkovy, Wang, 2005) too low kick velocities! electromagnetic vortices in color–superconducting (CSC) quark matter (Berdermann, Blaschke, Grigorian, Voskresensky, 2005) no electromagnetic vortices in standard CSC quark matter! anisotropy in neutrino-driven supernova explosion (Scheck, Kifonidis, Janka, Müller, 2006) needs artificially increased –interaction for successful explosion! J. Schaffner-Bielich, Goethe University, Frankfurt – p.26/27 Gravitational wave signal from strange quark matter?
M=1.35M sol −3.8
−3.9
−4 (f)
−4.1x h
−4.2
−4.3
−4.4 3.2 3.25 3.3 3.35 3.4 log(f) M=1.4M sol −3.4
−3.6
−3.8
−4 (f)
x −4.2 h
−4.4
−4.6 −4.8 binary neutron star mergers with a quark core: signal clearly −5 3 3.1 3.2 3.3 3.4 3.5 log(f) M=1.5M sol seen in different Fourier spectrum! −3.5
−4 (Oechslin, Uryu,¯ Pogosyan, Thielemann 2004)
−4.5 (f) x h −5 binary strange quark star collision: higher frequencies −5.5 possible before ’touch-down’ compared to normal neutron
−6 3 3.1 3.2 3.3 3.4 3.5 3.6 log(f) M=1.75M stars sol −3
−3.5 (Limousin, Gondek-Rosinska, Gourgoulhon 2005)
−4 (f)
−4.5x h collapse of neutron star to quark matter: sensitive to EoS −5
−5.5 (Lin, Cheng, Chu, Suen 2006)
−6 2.8 3 3.2 3.4 3.6 3.8 4 log(f) J. Schaffner-Bielich, Goethe University, Frankfurt – p.27/27