11411115
Newtonian and general relativistic contribution of gravity to surface tension of strange stars
Surface tension (S ) is due to the inward force experienced by particles at the surface and usually gravitation does not play an important role in this force. But in compact stars the gravitational force on the particles is very large and S is found to depend not only on the interactions in the strange quark matter, but also on the structure of the star, i.e. on its mass and radius. Indeed, it has been claimed recently that 511 keV photons observed by the space probe INTEGRAL from the galactic bulge may be due to e + e − annihilation, and their source may be the positron cloud outside of an antiquark star. Such stars, if they exist, may also go a long way towards explaining away the antibaryon deficit of the universe. For that to happen S must be high enough to allow for survival of quark/antiquark stars born in early stages of the formation of the universe. High value of S may also assist explanation of delayed γ-ray burst after a supernova explosion, as conversion from normal matter to strange matter takes place. The possibility of some implications from formation of surface waves are also discussed.
127351407
Color Singlet Hadron Formation and Phase Transition to Quark - Gluon Plasma in the Bag Model
15993375
Double neutron stars as double strange stars
Double neutron star systems lead to strong tests of general r lativity. The history of the double pulsar PSR J0737−3039 is also very interesting. There are claims that the youn ger member of this binary (pulsar B) had a light progenitor. It is possible that such double pulsar systems are double str ange stars. We suggest that the collapse of the light progeni tor was a phase transition to strange matter and J0737 −3039B is a strange star. This would support small baryon loss implied by the small natal kick velocity for the system J0737 −3039. Using equation of states for strange quark matter and n eutron matter, we have calculated the stellar structure and the baryon conten t of the progenitor as well as the existing star to compare wi th observational predictions. We have also calculated the moment of i ertia using both of the equation of states to facilitate co mparison with expected future measurements. The baryon number of the progenitor turns out to be ∼ 2× 1057 and with small baryon loss the this fits into a strange star of mass 1.25 M⊙. Double neutron stars may be double strange stars. If the mom ent of inertia of these stars are found in the near future as expected, then our predictions can be further tested.
120717106
QCD — MOTIVATED QUARK STARS IN THE LIGHT OF RECENT ASTROPHYSICAL OBSERVATIONS
Are there quark stars in nature? We review the question in the light of modern astrophysical observations. Quark stars have properties which are very similar to those of neutron stars. For example they are now known to have the same kind of cooling properties. Their masses may also be similar. On the other hand, gamma ray bursts (GRB), the brightest phenomenon observable at present in the sky, could possibly be conversion of normal or neutron matter on the surface of a quark star. The best observational evidence for the existence of quark stars seems to be some compact objects, the X-Ray burst source 4U 1820-30, the X-ray pulsar Her X-1, the star 4U 1728-34 and SAX J-1808.4-3658, this last one being the stablest and fastest rotating hard X-ray pulsar known to date. The mass of at least these four objects is high and their radius is low, placing them close to the black hole line, in the mass–radius (M–R) plot.
14202199
Entropy and equation of state for dense hot quark matter and its effect on compact quark stars
Dey et al. [1] derived an equation of state (EOS) for matter in strange stars (SS from hereon) with quark masses showing chiral symmetry restoration (CSM) and an interquark potential which (i) has asymptotic freedom built into it, (ii) shows confinement at zero density (ρB = 0) and deconfinement at high ρB. This EOS gives a stable configuration for chargeless, β-stable quark matter. The SS derived from this EOS fits into the empirical mass -radius (M-R) relations of some stars constraining the CSM parameters [1, 2, 3]. In the present paper we extend the calculation to include high temperatures upto T = 10 MeV ≡ 1.16 × 10 K where the quark gas is still degenerate and find that the empirical M-R relation, derived from astrophysical data, is still satisfied. The EOS is tabulated for T = 10 MeV . The entropy is calculated and matches onto that calculated from hadronic models thus supporting the idea that the quark-hadron transition may be continuous. (1) Dept. of Physics, Presidency College, Calcutta 700 073, India (2) Azad Physics Centre, Dept. of Physics, Maulana Azad College, Calcutta 700 013, India (3) Abdus Salam ICTP, Trieste, Italy (4) Department of Physics, Burdwan University, Burdwan 713104, India. † permanent address; 1/10 Prince Golam Md. Road, Calcutta 700 026, India, e-mail : deyjm@giascl01.vsnl.net.in ** Suported by DST Grant no. SP/S2/K18/96, Govt. of India.
120924061
IS THERE A SPIN 1/2 WEAK DOUBLET OF SKYRMIONS ALMOST DEGENERATE WITH W AND Z?
73632693
Antiproton acceleration in the Fermilab Main Injector using 2.5 MHz (H=28) and 53 MHz (H=588) RF systems
During the Run II era at Fermilab, the Recycler stores antiprotons at 8 GeV and the Main Injector accelerates the antiprotons and the protons from 8 GeV to 150 GeV for Tevatron injection. The Recycler injects antiprotons to the Main Injector in 2.5 MHz rf buckets. This report presents an acceleration scheme for the antiprotons that involves a slow ramp with initial 2.5 MHz acceleration and subsequent fast acceleration with 53 MHz rf system. Beam acceleration and rf manipulation with space charge and beam loading effects are simulated using the longitudinal simulation code ESME. Simulation suggests that one can expect about 15% emittance growth for the entire acceleration cycle with beam loading compensations. Preliminary experimental results with proton beam will also be presented.
109094861
Modification of Linac 7651 driver to operate at 425 MHz