73652372
Asteroseismology of Vibration Powered Neutron Stars
There is a general recognition today that basic features of asteroseismology of non-convective ﬁnalstage (FS) stars, such as white dwarfs, neutron stars and and strange quark star, can be properlyunderstood working from the model of vibrating solid star, rather than the liquid star model lyingat the base of asteroseismology of convective main-sequence (MS) stars. In accord with this, mostof current investigations of an FS-star vibrations rests on principles of solid-mechanical theory ofcontinuous media, contrary to the study of the MS-star vibrations which are treated in terms of ﬂuid-mechanical theory. This means that super dense matter of FS-stars (whose gravitational pressureis counterbalanced by degeneracy pressure of constituting Fermi-matter), possesses elasticity andviscosity generic to solid state of condensed matter, whereas a fairly dilute matter of the MS (whoseinternal pressure of self-gravity is opposed by radiative pressure) possesses property of ﬂuidity whichis generic to the liquid state of a highly conducting condensed matter. This feature of the MS-starmatter plays crucial role in generation of their magnetic ﬁelds in the dynamo processes involvingmacroscopic ﬂows which are supported by energy of nuclear reactions in the central, reactive zone,of these stars. In the meantime, in the FS stars, like white dwarfs and neutron stars, there are nonuclear energy sources to support convection. The prevailing today view, therefore, is that a highlystable to spontaneous decay dipolar magnetic ﬁelds of neutron stars are fossil. The extremely largeintensity of magnetic ﬁelds of degenerate solid stars is attributed to ampliﬁcation of fossil magneticﬁeld in the magnetic-ﬂux-conserving process of core-collapse supernova.Even still before discovery of neutron stars, it has been realized that, for absence of nuclearsources of energy, the radiative activity of these of compact objects should be powered by energy ofstored in either rotation or vibrations and that the key role in maintaining the neutron star radiationshould play an ultra strong magnetic ﬁeld. As is commonly know today, the neutron star capabilityof accommodating such a ﬁeld is central to understanding pulsating character of magneto-dipoleradiation of radio pulsars whose radiative power is provided, as is commonly believed, by the energyof rigid-body rotation. The discovery of soft gamma-ray repeaters and their identiﬁcation withmagnetars [1] – quaking neutron stars endowed with ultra strong magnetic ﬁelds experiencing decay– has stimulated enhanced interest in the study of models of quake-induced magneto-mechanicalseismic vibrations of neutron star and resultant electromagnetic radiation. Of particular interestin this study are torsional magneto-mechanical vibrations about axis of magnetic dipole momentof the star driven by forces of magnetic-ﬁeld-dependent stresses in a perfectly conducting matterand in a permanently magnetized non-conducting matter [2]. Most, if not all, reported up to nowcomputations of frequency spectra of poloidal and toroidal Alfv´en vibration modes in pulsars andmagnetars rest on tacitly adopted assumption about constant-in-time magnetic ﬁeld in which aperfectly conducting neutron star matter undergoes Lorentz-force-driven oscillations [3, 4, 5, 6, 7,8, 9, 10, 11, 12] (see, also, references therein). A special place in the study of the above Alfv´enmodes of pure shear magneto-mechanical seismic vibrations (a-modes) occupies a homogeneousmodel of a solid star with the uniform density ρ and frozen-in poloidal static magnetic ﬁeld of bothhomogeneous and inhomogeneous internal and dipolar external conﬁguration, and we start section2 with a brief outline of this model. In section 3, a mathematical background of quaking neutronstar model is brieﬂy outlined with emphasis on the loss of vibration energy caused by depletion ofinternal magnetic ﬁeld pressure and resulting vibration-energy powered magneto-dipole radiation.The decreasing of magnetic ﬁeld pressure in the star is presumed to be caused by coupling betweenvibrating star and outgoing material which is expelled by quake, but mechanisms of star-envelopeinteraction resulting in the decay of magnetic ﬁeld, during the time of vibrational relaxation, are2
119279262
PSR B1257+12: a quark star with planets?
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.
118541626
H-cluster stars
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.
118508611
The state of cold quark matter: a model-independent view
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.
118501168
The Extremely Long-period X-Ray Source in a Young Supernova Remnant: A Thorne-Żytkow Object Descendant?
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.
117033142
Are AXPs/SGRs magnetars?
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.
125676969
Observation of $D(s$)+ $\to \bar{K}0 K^+$ and $D(s$)+ $\to \bar{K}^*0 K^+$ and an Upper Limit on $D(s$)+ $\to K^0 \pi^+$
54821283
Limit on B(s)0 oscillation using a jet charge method
A lower limit is set on the B_{s}^{0} meson oscillation parameter \Delta m_{s} using data collected from 1991 to 1994 by the ALEPH detector. Events with a high transverse momentum lepton and a reconstructed secondary vertex are used. The high transverse momentum leptons are produced mainly by b hadron decays, and the sign of the lepton indicates the particle/antiparticle final state in decays of neutral B mesons. The initial state is determined by a jet charge technique using both sides of the event. A maximum likelihood method is used to set a lower limit of \, \Delta m_{s}. The 95\% confidence level lower limit on \Delta m_s ranges between 5.2 and 6.5(\hbar/c^{2})~ps^{-1} when the fraction of b quarks from Z^0 decays that form B_{s}^{0} mesons is varied from 8\% to 16\%. Assuming that the B_{s}^{0} fraction is 12\%, the lower limit would be \Delta m_{s} 6.1(\hbar/c^{2})~ps^{-1} at 95\% confidence level. For x_s = \Delta m_s \, \tau_{B_s}, this limit also gives x_s 8.8 using the B_{s}^{0} lifetime of \tau_{B_s} = 1.55 \pm 0.11~ps and shifting the central value of \tau_{B_s} down by 1\sigma.
17926047
Study of the fragmentation of b quarks into B mesons at the Z peak
The fragmentation of b quarks into B mesons is studied with four million hadronic Z decays collected by the ALEPH experiment during the years 1991-1995. A semi-exclusive reconstruction of B->l nu D(*) decays is performed, by combining lepton candidates with fully reconstructed D(*) mesons while the neutrino energy is estimated from the missing energy of the event. The mean value of xewd, the energy of the weakly-decaying B meson normalised to the beam energy, is found to be mxewd = 0.716 +- 0.006 (stat) +- 0.006 \, (syst) using a model-independent method; the corresponding value for the energy of the leading B meson is mxel = 0.736 +- 0.006 (stat) +- 0.006 (syst). The reconstructed spectra are compared with different fragmentation models.
73681500
Measurement of the effective b quark fragmentation function at the Z resonance
Using a sample of about 1.46 million hadronic Z decays collected between 1991 and 1993 with the ALEPH detector at LEP, the energy distribution of the B0 and B± mesons produced at the Z resonance is measured by reconstructing semileptonic decays B → lνlD(X) or . The charmed mesons are reconstructed through the decay modes D0 → K−π+, D0 → K−π+π−π+, D+ → K−π+π+ and . The neutrino energy is estimated from the missing energy in the lepton hemisphere. Accounting for B∗ and B∗∗ production, the shape of the scaled energy distribution xE(b) for mesons containing a b quark is compared to the predictions of different fragmentation models. The mean value of xE(b) is found to be 〈xE(b)〉 = 0.715 ± 0.007(stat) ± 0.013(syst).
16638912
The forward-backward asymmetry for charm quarks at the Z pole
From 1.4 million hadronic Z decays collected by the ALEPH detector at LEP, an enriched sample of Z → cc events is extracted by requiring the presence of a high momentum D∗±. The charm quark forward-backward charge asymmetry at the Z pole is measured to be AFB0.c = (8.0 ± 2.4) % corresponding to an effective electroweak mixing angle of sin2θWeff = 0.2302 ± 0.0054.