DISTRIBUTIONAL TORSION OF COSMIC STRINGS WITH POLARIZED SPINNING MATTER

1998 ◽  
Vol 13 (27) ◽  
pp. 2227-2230 ◽  
Author(s):  
L. C. GARCIA DE ANDRADE
Keyword(s):  
Angular Momentum ◽  
Cosmic String ◽  
Cosmic Strings ◽  
Finite Size ◽  
The Other ◽  
Spinning Particles ◽  
Point Particles ◽  
Cartan Torsion ◽  
Spin Polarized ◽  
Dirac Distribution

A cosmic string of finite size in Weitzenböck space–time is built where spin polarized particles can be found along the string and orthogonal to it. Only spinning particles polarized along the string contribute to the angular momentum of the string while the other is only a torsion source like in Einstein–Cartan (EC) theory. Cartan torsion is given by a δ-Dirac distribution and the metric is the lift of (2+1)-gravity point particles to (3+1)-cosmic strings.

MULTI-BLACK HOLES SOLUTION WITH COSMIC STRINGS

2004 ◽  
Vol 19 (10) ◽  
pp. 1549-1557 ◽  
Author(s):  
F. ÖZDEMIR ◽  
N. ÖZDEMIR ◽  
B. T. KAYNAK
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Cosmic String ◽  
Circular Orbit ◽  
Cosmic Strings ◽  
De Sitter ◽  
Circular Orbits ◽  
Small Oscillations ◽  
String Models

Some black hole-cosmic string models such as Reissner–Nordström, RN–de Sitter, Kerr–Newman and multi-black holes with cosmic string are given. Energy and angular momentum of a timelike particle in circular orbits in multi-black hole space–time are calculated. The geodesic equations for the timelike particles for the far region of the multi-black hole sources are calculated and small oscillations around the circular orbit obtained. It is seen that the particle's orbit precesses like the Lens–Thirring effect.

FERMIONIC CURRENTS ALONG COSMIC STRINGS

2002 ◽  
Vol 17 (20) ◽  
pp. 2773-2773
Author(s):  
C. RINGEVAL
Keyword(s):  
Cosmic String ◽  
Propagation Velocity ◽  
Bound States ◽  
Cosmic Strings ◽  
Higgs Field ◽  
The Other ◽  
Transverse Perturbation ◽  
Classical Stability ◽  
Perturbation Propagation ◽  
Exhaustive Study

A Yukawa coupling of fermions to the string forming Higgs field leads to the existence of massless1 and massive2,3 fermionic bound states in the vortex that can drastically modify the string dynamics3,4. An exhaustive study of these states is performed. In particular, it is shown that there exists transitions between subsonic and supersonic regimes (i.e. regimes in which the transverse perturbation propagation velocity is less or greater than the longitudinal, sound-like one, respectively), which appear as soon as the massless and massive modes are respectively filled5. This results in modifying the classical stability of cosmic string loops. On the other hand, this confinement mechanism can also be transposed to the the brane context as a viable way for localizing fermions on the brane6.

DISTRIBUTIONAL TORSION OF HYBRID DEFECTS

1999 ◽  
Vol 14 (25) ◽  
pp. 1719-1723 ◽  
Author(s):  
L. C. GARCIA DE ANDRADE
Keyword(s):  
Domain Wall ◽  
Cosmic String ◽  
Cosmic Strings ◽  
Matter Density ◽  
Cartan Torsion ◽  
Planar Wall

Distributional sources of cosmic walls crossed by cosmic strings are obtained from Riemann–Cartan (RC) geometry. The matter density of the planar wall is maximum at the point where the cosmic string crosses the cosmic wall. Cartan torsion has support on the cosmic string given by the Dirac δ-function. Off the sources we are left with a torsionless vacuum. It is suggested that this hybrid defect geometry with torsion may serve as a model for a spinning string from a quark which ends on an axionic domain wall.

scholarly journals Searching for gravitational-wave bursts from cosmic string cusps with the Parkes Pulsar Timing Array

2020 ◽  
Vol 501 (1) ◽  
pp. 701-712
Author(s):  
N Yonemaru ◽  
S Kuroyanagi ◽  
G Hobbs ◽  
K Takahashi ◽  
X-J Zhu ◽  
...  
Keyword(s):  
False Alarm ◽  
Gravitational Wave ◽  
Cosmic String ◽  
Cosmic Strings ◽  
False Alarm Probability ◽  
String Tension ◽  
Detection Algorithm ◽  
Pulsar Timing ◽  
Upper Limits ◽  
Pulsar Timing Array

ABSTRACT Cosmic strings are potential gravitational-wave (GW) sources that can be probed by pulsar timing arrays (PTAs). In this work we develop a detection algorithm for a GW burst from a cusp on a cosmic string, and apply it to Parkes PTA data. We find four events with a false alarm probability less than 1 per cent. However further investigation shows that all of these are likely to be spurious. As there are no convincing detections we place upper limits on the GW amplitude for different event durations. From these bounds we place limits on the cosmic string tension of Gμ ∼ 10−5, and highlight that this bound is independent from those obtained using other techniques. We discuss the physical implications of our results and the prospect of probing cosmic strings in the era of Square Kilometre Array.

scholarly journals PROPERTIES OF ACCRETION SHOCKS IN VISCOUS FLOWS WITH COOLING EFFECTS

2004 ◽  
Vol 13 (09) ◽  
pp. 1955-1972 ◽  
Author(s):  
SANTABRATA DAS ◽  
SANDIP K. CHAKRABARTI
Keyword(s):  
Shock Wave ◽  
Angular Momentum ◽  
Shock Waves ◽  
Thermodynamic Parameters ◽  
Parameter Space ◽  
Viscous Flows ◽  
Critical Value ◽  
The Other ◽  
Accretion Flows ◽  
Cooling Effects

Low angular momentum accretion flows can have standing and oscillating shock waves. We study the region of the parameter space in which multiple sonic points occur in viscous flows in presence of various cooling effects such as bremsstrahlung and Comptonization. We also quantify the parameter space in which shocks are steady or oscillating. We find that cooling induces effects opposite to heating by viscosity even in modifying the topology of the solutions, though one can never be exactly balanced by the other due to their dissimilar dependence on dynamic and thermodynamic parameters. We show that beyond a critical value of cooling, the flow ceases to contain a shock wave.

scholarly journals Angle deficit and nonlocal gravitoelectromagnetism around a slowly spinning cosmic string

2020 ◽  
Vol 29 (14) ◽  
pp. 2043027
Author(s):  
Jens Boos
Keyword(s):  
Gravitational Field ◽  
Symmetry Breaking ◽  
Early Universe ◽  
Physical Interpretation ◽  
Cosmic String ◽  
Cosmic Strings ◽  
Radial Distance ◽  
Gravitomagnetic Field ◽  
Simply Connected

Cosmic strings, as remnants of the symmetry breaking phase in the Early universe, may be susceptible to nonlocal physics. Here, we show that the presence of a Poincaré-invariant nonlocality—parametrized by a factor [Formula: see text]—regularizes the gravitational field and thereby changes the properties of spacetime: it is now simply connected and the angle deficit around the cosmic string becomes a function of the radial distance. Similar changes occur for the nonlocal gravitomagnetic field of a rotating cosmic string, and we translate these mathematical facts into the language of nonlocal gravitoelectromagnetism and thereby provide a physical interpretation. We hope that these insights might provide a helpful perspective in the search for traces of nonlocal physics in our universe.

scholarly journals The Near-Synchronous Polar Candidate V4633 Sgr (Nova Sagittarii 1998)

2004 ◽  
Vol 190 ◽  
pp. 176-177
Author(s):  
Y. Lipkin ◽  
E. M. Leibowitz
Keyword(s):  
Angular Momentum ◽  
Momentum Transfer ◽  
White Dwarf ◽  
Moment Of Inertia ◽  
The Other ◽  
Angular Momentum Transfer ◽  
Classical Nova ◽  
Order Of Magnitude ◽  
Photometric Monitoring ◽  
The Moment

AbstractThe classical nova V4633 Sgr (1998) exhibits two photometric periodicities. The shorter period (P1=3.01 hr) is stable, while the other one, longer by ~2.5%, has decreased monotonically since shortly after the nova eruption, with Ṗ2 ≈ –10−6 (Lipkin et al. 2001).Here we report on results of photometric monitoring of the star in 2001 and 2002. During our observations, the longer period decreased more, and in 2002 it was only 1.8% longer than P1 The decrease rate (Ṗ2) in 2001-2002 was an order of magnitude smaller than in 1998-2000.These new results support the Near-Synchronous Polar classification which was suggested for V4633 Sgr (Lipkin et al. 2001). In this model, the longer period of V4633 Sgr is the spin of the white dwarf, and its variation since 1998 reflects changes in the moment of inertia of the white dwarf, and angular momentum transfer in the system following the nova eruption.

The contribution of valence quarks in the nucleon GE and GM

2019 ◽  
Vol 34 (27) ◽  
pp. 1950148
Author(s):  
Negin Sattary Nikkhoo ◽  
Mohammad Reza Shojaei
Keyword(s):  
Experimental Data ◽  
Angular Momentum ◽  
Form Factor ◽  
Total Angular Momentum ◽  
Form Factors ◽  
Distribution Functions ◽  
The Other ◽  
Parton Distribution Functions ◽  
Nucleon Electromagnetic Form Factor ◽  
Elastic Form

The goal of this paper is to extract the flavor decomposition of nucleon electromagnetic form factor using the modified Gaussian and extended Regge ansatzes in the GPDs. We consider the CJ15 and JR09 parton distribution functions for both of these ansatzes in calculating the nucleon elastic form factors. Our results are compared with experimental data in the range [Formula: see text] 4-momentum transfers. Also, we calculate the total angular momentum carried by quarks, the gravitational form factors, and the transverse gravitational density for quarks of the nucleon. In the end, our results are compared with the other studies.

scholarly journals PERSISTENCE IN THE ZERO-TEMPERATURE DYNAMICS OF THE Q-STATES POTTS MODEL ON UNDIRECTED-DIRECTED BARABÁSI–ALBERT NETWORKS AND ERDÖS–RÉNYI RANDOM GRAPHS

2008 ◽  
Vol 19 (12) ◽  
pp. 1777-1785 ◽  
Author(s):  
F. P. FERNANDES ◽  
F. W. S. LIMA
Keyword(s):  
Random Graphs ◽  
Potts Model ◽  
Finite Size ◽  
Glauber Dynamics ◽  
The Other ◽  
Finite Size Effect ◽  
Zero Temperature ◽  
Temperature Dynamics ◽  
Short Times ◽  
Q Values

The zero-temperature Glauber dynamics is used to investigate the persistence probability P(t) in the Potts model with Q = 3, 4, 5, 7, 9, 12, 24, 64, 128, 256, 512, 1024, 4096, 16 384, …, 230 states on directed and undirected Barabási–Albert networks and Erdös–Rényi (ER) random graphs. In this model, it is found that P(t) decays exponentially to zero in short times for directed and undirected ER random graphs. For directed and undirected BA networks, in contrast it decays exponentially to a constant value for long times, i.e., P(∞) is different from zero for all Q values (here studied) from Q = 3, 4, 5, …, 230; this shows "blocking" for all these Q values. Except that for Q = 230 in the undirected case P(t) tends exponentially to zero; this could be just a finite-size effect since in the other "blocking" cases you may have only a few unchanged spins.

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