<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2006000900029</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[On the existence of conformal Killing vectors for ST-homogeneous Godel type space-times]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Parra]]></surname>
<given-names><![CDATA[Y]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Patino]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Percoco]]></surname>
<given-names><![CDATA[U]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Tsamparlis]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
<xref ref-type="aff" rid="A03"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad de los Andes Facultad de Ciencias Departamento de Física]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Venezuela</country>
</aff>
<aff id="A02">
<institution><![CDATA[,Universidad de los Andes Facultad de Ciencias Departamento de Física]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Venezuela</country>
</aff>
<aff id="A03">
<institution><![CDATA[,Universidad de Atenas Departamento de Física Sección de Astronomía-Astrofísica-Mecánica]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Grecia</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>05</month>
<year>2006</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>05</month>
<year>2006</year>
</pub-date>
<volume>52</volume>
<fpage>102</fpage>
<lpage>104</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2006000900029&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2006000900029&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2006000900029&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Tsamparlis et al. [3] have developed a systematic method for computing of the conformal algebra of 1+3 space-times. The proper CKV's are found in terms of gradient CKVs of the 3-space. In this paper we apply Tsamparlis' results to the study CKVs of the Godel ST-Homogeneous type spacetimes. We find that the only space-time admitting proper CKV's is the ST-Homogeneous Gödel type with m² = 4&#937;² (RT).]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Tsamparlis et al. [3] han encontrado un método sistemático para calcular el álgebra conforme de espacio-tiempos 1+3. Los CKV's propios son encontrados en términos de los gradientes CKV's del 3-espacio. En este trabajo aplicamos los resultados de Tsamparlis para estudiar los CKVs del espacio-tiempo tipo Godel ST-Homogeneo. Encontramos que el único espacio-tiempo que admite CKVs propios es el tipo Gödel ST-Homogeneo con m² = 4&#937;² (RT).]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[General relativity]]></kwd>
<kwd lng="en"><![CDATA[conformal symmetries]]></kwd>
<kwd lng="es"><![CDATA[Relatividad general]]></kwd>
<kwd lng="es"><![CDATA[simetrías conformes]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">F&iacute;sica Te&oacute;rica </font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><b>On the existence of conformal Killing vectors for ST&#150;homogeneous Godel type space&#150;times</b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>Y. Parra*,  A. Patino*, U. Percoco** and M. Tsamparlis***</b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>* Laboratorio de F&iacute;sica Te&oacute;rica, Departamento de F&iacute;sica, Facultad de Ciencias Universidad de los Andes, </i><i>M&eacute;rida 5101, Venezuela</i></font></p>     <p align="justify"><font face="verdana" size="2"><i>** Centro de Astrof&iacute;sica Te&oacute;rica, Departamento de F&iacute;sica, Facultad de Ciencias Universidad de los Andes, M&eacute;rida 5101, Venezuela</i></font></p>     <p align="justify"><font face="verdana" size="2"><i>*** Secci&oacute;n de Astronom&iacute;a&#150;Astrof&iacute;sica&#150;Mec&aacute;nica, Departamento de F&iacute;sica, Universidad de Atenas, </i><i>Atenas 157 83, Grecia</i></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">Recibido el 24 de noviembre de 2003    <br> Aceptado el 19 de junio de 2004</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">Tsamparlis <i>et al. </i>&#91;3&#93; have developed a systematic method for computing of the conformal algebra of 1+3 space&#150;times. The proper CKV's are found in terms of gradient CKVs of the 3&#150;space. In this paper we apply Tsamparlis' results to the study CKVs of the Godel ST&#150;Homogeneous type spacetimes. We find that the only space&#150;time admitting proper CKV's is the ST&#150;Homogeneous G&ouml;del type with <i>m<sup>2</sup> </i>= 4&Omega;<sup>2</sup> (RT).</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords:</b>  General relativity; conformal symmetries.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     <p align="justify"><font face="verdana" size="2">Tsamparlis <i>et al. </i>&#91;3&#93; han encontrado un m&eacute;todo sistem&aacute;tico para calcular el &aacute;lgebra conforme de espacio&#150;tiempos 1+3. Los CKV's propios son encontrados en t&eacute;rminos de los gradientes CKV's del 3&#150;espacio. En este trabajo aplicamos los resultados de Tsamparlis para estudiar los CKVs del espacio&#150;tiempo tipo Godel ST&#150;Homogeneo. Encontramos que el &uacute;nico espacio&#150;tiempo que admite CKVs propios es el tipo G&ouml;del ST&#150;Homogeneo con <i>m<sup>2</sup> </i>= 4&Omega;<sup>2</sup> (RT).</font></p>     <p align="justify"><font face="verdana" size="2"><b>Descriptores:</b> Relatividad general; simetr&iacute;as conformes.</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">PACS: 04.20.&#150;q</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v52s3/v52s3a29.pdf">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Acknowledgments</b></font></p>     <p align="justify"><font face="verdana" size="2">This work was supported by CDCHT&#150;ULA(C&#150;982&#150;99&#150;05&#150;B), CDCHT&#150;ULA (C&#150;1005&#150;00&#150;05&#150;ED) and FONACIT (S1&#150;2000000820).</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. A. A. Coley and B. O. J. Tupper, <i>J. Math. Phys. </i><b>33</b> (1992) 1754.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326456&pid=S0035-001X200600090002900001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">2. M.S. Capocci and G. S. Hall, <i>Gravitation Cosmology </i><b>3</b> (1997) 1.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326457&pid=S0035-001X200600090002900002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">3. M. Tsamparlis, D. Nikolopoulos, and P. Apostolopoulos, <i>Class. Quantum Grav. </i>(submitted).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326458&pid=S0035-001X200600090002900003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">4. K. G&ouml;del, <i>Rev. Mod. Phys. </i><b>21</b> (1949) 447.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326459&pid=S0035-001X200600090002900004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">5. M.J. Rebou&ccedil;as and J. Tiommo, <i>Phys. Rev. D </i><b>28</b> (1983) 1251.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326460&pid=S0035-001X200600090002900005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">6. A.K. Raychaudhuri and S.N.G. Thakurta, <i>Phys. Rev. D </i><b>22</b> (1980) 802.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326461&pid=S0035-001X200600090002900006&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">7. A.F.F. Texeira, M. J. Reboucas, and J.E. Aman, <i>Phys. Rev. D </i><b>32</b> (1985) 3309.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8326462&pid=S0035-001X200600090002900007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> ]]></body><back>
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