ASTRO-QUARK MATTER: A CHALLENGE FACING ASTROPARTICLE PHYSICS
Quark matter both in terrestrial experiment and in astrophysics is briefly reviewed. Astrophysical quark matter could appear in the early Universe, in compact stars, and as cosmic rays. Emphasis is put on quark star as the nature of pulsars. Possible astrophysical implications of experiment-discovered sQGP are also concisely discussed.

title: PSR B1257+12: a quark star with planets?
abstract: A recent observation has shown that PSR B1257+12 could have quite small X‐ray emitting area, only about 2000 m2, which is more than three orders smaller than the canonical polar cap size. We suggest here that PSR B1257+12 could be a low‐mass quark star with radius of R≃0.6 km and mass of M≃3×10−4 M⊙. Such a low‐mass quark star system may form in an accretion induced collapse process or a collision process of two quark stars.

title: The Extremely Long-period X-Ray Source in a Young Supernova Remnant: A Thorne-Żytkow Object Descendant?
abstract: The origin of the 6.67 hr period X-ray source, 1E161348-5055, in the young supernova remnant RCW 103 is puzzling. We propose that it may be the descendant of a Thorne-Żytkow Object (TŻO). A TŻO may at its formation have a rapidly spinning neutron star as a core and a slowly rotating envelope. We found that the core could be braked quickly to an extremely long spin period by the coupling between its magnetic field and the envelope, and that the envelope could be disrupted by some powerful bursts or exhausted via stellar wind. If the envelope is disrupted after the core has spun down, the core will become an extremely long-period compact object, with a slow proper motion speed, surrounded by a supernova-remnant-like shell. These features all agree with the observations of 1E161348-5055. TŻOs are expected to have produced extraordinarily high abundances of lithium and rapid proton process elements that would remain in the remnants and could be used to test this scenario.

title: The state of cold quark matter: a model-independent view
abstract: From a model-independent point of view, we address the possibility that quark clustering could occur in cold quark matter at realistic baryon densities because of the likely strong coupling between quarks in compact stars.

title: Are AXPs/SGRs magnetars?
abstract: Anomalous X-ray Pulsars and Soft Gamma-Ray Repeaters have been generally recognized as neutron stars with super strong magnetic fields, namely "magnetars". The "magnetars" manifest that the luminosity in X-ray band are larger than the rotational energy loss rate, i.e. $L_{X}>\dot {E}_{\rm rot}$, and then the radiation energy is coming from the energy of magnetic field. Here it is argued that magnetars may not really exist. Some X-ray and radio observational results are contradicted with the magnetar model. 
(1) The X-ray luminosity of PSR J1852+0040 is much larger than the rotational energy loss rate ($L_{X}/\dot {E}_{\rm rot}\simeq 18)$, but the magnetic field is just $3.1\times 10^{11}$ G. Does this X-ray radiation energy come from the magnetic field? 
(2) In contrast to the above, the magnetic fields of radio pulsars J1847-0130 and PSR J1718-3718 are higher than that of AXP 1E 2259+586, why is the radiation energy of those two radio pulsars still coming from rotational energy? Furthermore, the magnetic field of the newly discovered SGR 0418+5729 with the lowest magnetic field is 3.0 e13 G, lower than the critical magnetic field $B_{\rm C}=4.414$ e13 G) (Esposito et al. 2010). 
(3) Some "magnetars" also emit normal transient radio pulses, what is the essential difference between radio pulsars and the "magnetars"? 
The observational fact arguments will be presented at first, then we discuss in what situation the conventional method to obtain magnetic field could not be correct.

title: H-cluster stars
abstract: The study of dense matter at ultra-high density has a very long history, which is meaningful for us to understand not only cosmic events in extreme circumstances but also fundamental laws of physics. It is well known that the state of cold matter at supra-nuclear density depends on the non-perturbative nature of quantum chromo-dynamics (QCD) and is essential for modeling pulsars. A so-called H-cluster matter is proposed in this paper as the nature of dense matter in reality. 
In compact stars at only a few nuclear densities but low temperature, quarks could be interacting strongly with each other there. That might render quarks grouped in clusters, although the hypothetical quark-clusters in cold dense matter has not been confirmed due to the lack of both theoretical and experimental evidence. Motivated by recent lattice QCD simulations of the H-dibaryons (with structure uuddss), we are therefore considering here a possible kind of quark-clusters, H-clusters, that could emerge inside compact stars during their initial cooling, as the dominant components inside (the degree of freedom could then be H-clusters there).Taking into account the in-medium stiffening effect, we find that at baryon densities of compact stars $H$-cluster matter could be more stable than nuclear matter. We also find that for the H-cluster matter with lattice structure, the equation of state could be so stiff that it would seem to be "superluminal" in most dense region. However, the real sound speed for H-cluster matter is in fact hard to calculate, so at this stage we do not put constraints on our model from the usual requirment of causality.

title: A measurement of Rb using mutually exclusive tags
abstract: A measurement of Rb using five mutually exclusive hemisphere tags has been performed by ALEPH using the full LEP1 statistics. Three tags are designed to select the decay of the Z0 to b quarks, while the remaining two select Z0 decays to c and light quarks, and are used to measure the tagging efficiencies. The result, Rb = 0.2159 ± 0.0009(stat) ±0.0011(syst), is in agreement with the electroweak theory prediction of 0.2158 ± 0.0003.

title: Nucleon sea in the effective chiral quark model
abstract: The asymmetries of both light-flavor antiquark d(x)-u(x) and strange-antistrange s(x)-s(x) distributions of the nucleon sea are considered with more details in the effective chiral quark model. We find that the asymmetric distribution of light-flavor antiquarks d(x)-u(x) matches the experimental data well and that the asymmetry of strange and antistrange distributions can bring about 60%-100% correction to the NuTeV anomaly of sin{sup 2}{theta}{sub w}, which are 3 standard deviations from the world average value measured in other electroweak processes. The results on the correction to the NuTeV anomaly are insensitive to the inputs of the constituent quark distributions and the cutoff parameters. The ratios of d(x)/u(x) and s(x)/s(x) are also discussed, and it is found that the ratio s(x)/s(x) is compatible with the available experiments with an additional symmetric sea contribution being considered effectively.

title: Effect of asymmetric strange–antistrange sea to the NuTeV anomaly
abstract: We calculate the strange quark and antiquark distributions of the nucleon by using the effective chiral quark model, and find that the strange–antistrange asymmetry can bring a contribution of about 60–100% to the NuTeV deviation of sin 2 θ w from the standard value measured in other electroweak processes. The results are insensitive to different inputs. The light-flavor quark asymmetry of d ¯ – u ¯ is also investigated and found to be consistent with the experimental measurements. Therefore the chiral quark model provides a successful picture to understand the NuTeV anomaly, as well as the light-flavor quark asymmetry and the proton spin problem in previous studies.

title: Heavy flavour production and decay with prompt leptons in the ALEPH detector
abstract: AbstractIn 431 000 hadronicZ decays recorded with the ALEPH detector at LEP, the yields of electrons and muons in events with one or more prompt leptons have been analysed to give information on the production and decay of heavy quarks. The fractions of
$$b\bar b$$
 and
$$c\bar c$$
 events are measured to be 0.219±0.006±0.005 and 0.165±0.005±0.020, and the corresponding forward-backward asymmetries at theZ mass are measured to be 0.090±0.013±0.003 and 0.111±0.021±0.018, after QED and QCD corrections. Measurements for the semileptonic branching ratios BR
$$(b \to \ell ^ - \bar vX)$$
 and BR (b→cℓ+vX) yield 0.114±0.003±0.004 and 0.082±0.003±0.012, respectively. The dilepton events enable measurement of theb mixing parameter, Χ=0.114±0.014±0.008. Results are also presented for the energy variation of the
$$b\bar b$$
 asymmetry and the parameters required to describe heavy quark fragmentation. From the asymmetry measurements, the effective electroweak mixing angle is sin2θWeff=0.2333±0.0022.

title: Measurement of Lambda polarization from Z decays
abstract: The polarization of Λ baryons from Z decays is studied with the Aleph apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal Λ polarization is PLΛ = −0.32 ± 0.07 for . This agrees with the prediction of −0.39 ± 0.08 from the standard model and the constituent quark model, where the error is due to uncertainties in the mechanism for Λ production. The observed Λ polarization is diluted with respect to the primary s quark polarization by Λ baryons without a primary s quark. Measurements of the Λ forward-backward asymmetry and of the correlation between back-to-back Λ pairs are used to check this dilution. In addition the transverse Λ polarization is measured. An indication of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrust axis and the Λ direction.