<?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>S0035-001X2013000400011</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[SL(2,R)-geometric phase space and (2+2)-dimensions]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Flores]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Nieto]]></surname>
<given-names><![CDATA[J. A.]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Tellez]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Leon]]></surname>
<given-names><![CDATA[E. A.]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Estrada]]></surname>
<given-names><![CDATA[E. R.]]></given-names>
</name>
<xref ref-type="aff" rid="A03"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad de Sonora Departamento de Investigación en Física ]]></institution>
<addr-line><![CDATA[Hermosillo Sonora]]></addr-line>
<country>México</country>
</aff>
<aff id="A02">
<institution><![CDATA[,Universidad Autónoma de Sinaloa Facultad de Ciencias Físico-Matemáticas ]]></institution>
<addr-line><![CDATA[Culiacán Sinaloa]]></addr-line>
<country>México</country>
</aff>
<aff id="A03">
<institution><![CDATA[,Instituto Tecnológico Superior de Eldorado  ]]></institution>
<addr-line><![CDATA[Eldorado Sinaloa]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>08</month>
<year>2013</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>08</month>
<year>2013</year>
</pub-date>
<volume>59</volume>
<numero>4</numero>
<fpage>352</fpage>
<lpage>358</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2013000400011&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2013000400011&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2013000400011&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[We propose an alternative geometric mathematical structure for arbitrary phase space. The main guide in our approach is the hidden SL(2,R)-symmetry which acts on the phase space changing coordinates by momenta and vice versa. We show that the SL(2,R)-symmetry is implicit in any symplectic structure. We also prove that in any sensible physical theory based on the SL(2,R)-symmetry the signature of the flat target "spacetime" must be associated with either one-time and one-space or at least two-time and two-space coordinates. We discuss the consequences as well as possible applications of our approach on different physical scenarios.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Symplectic geometry]]></kwd>
<kwd lng="en"><![CDATA[constrained Hamiltonian systems]]></kwd>
<kwd lng="en"><![CDATA[two time physics]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[  	    <p align="justify"><font face="verdana" size="4">Research</font></p>  	    <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>              <p align="center"><font face="verdana" size="4"><b>SL(2,R)&#45;geometric phase space and (2+2)&#45;dimensions</b></font></p>              <p align="center"><font face="verdana" size="2">&nbsp;</font></p>  	    <p align="center"><font face="verdana" size="2"><b>R. Flores<sup>a</sup>, J. A. Nieto<sup>b,a</sup>, J. Tellez<sup>a</sup>, E. A. Leon<sup>b</sup>, and E. R. Estrada<sup>c</sup></b></font></p>              <p align="center"><font face="verdana" size="2">&nbsp;</font></p>              <p align="justify"><font face="verdana" size="2"><i><sup>a</sup> Departamento de Investigaci&oacute;n en F&iacute;sica de la Universidad de Sonora, 83000, Hermosillo Sonora, M&eacute;xico. </i>e&#45;mail: <a href="mailto:rflorese@gauss.mat.uson.mx">rflorese@gauss.mat.uson.mx</a>; <a href="mailto:jtellez@cajeme.cifus.uson.mx">jtellez@cajeme.cifus.uson.mx</a>.</font></p>              <p align="justify"><font face="verdana" size="2"><i><sup>b</sup> Facultad de Ciencias F&iacute;sico&#45;Matem&aacute;ticas de la Universidad Aut&oacute;noma de Sinaloa, 80010, Culiac&aacute;n Sinaloa, M&eacute;xico. </i>e&#45;mail: <a href="mailto:niet@uas.edu.mx">niet@uas.edu.mx</a>; <a href="mailto:janieto1@asu.edu">janieto1@asu.edu</a>; <a href="mailto:ealeon@uas.edu.mx">ealeon@uas.edu.mx</a>.</font></p>              <p align="justify"><font face="verdana" size="2"><i><sup>c</sup> Instituto Tecnol&oacute;gico Superior de Eldorado, Eldorado, Sinaloa, M&eacute;xico. </i>e&#45;mail: <a href="mailto:profe.emmanuel@gmail.com">profe.emmanuel@gmail.com</a><a href="mailto:profe.emmanuel@gmail.com"></a>.</font></p>              ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>              <p align="justify"><font face="verdana" size="2">Received 23 November 2012     <br>     Accepted 19 April 2013</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">We propose an alternative geometric mathematical structure for arbitrary phase space. The main guide in our approach is the hidden SL(2,R)&#45;symmetry which acts on the phase space changing coordinates by momenta and <i>vice versa.</i> We show that the SL(2,R)&#45;symmetry is implicit in any symplectic structure. We also prove that in any sensible physical theory based on the SL(2,R)&#45;symmetry the signature of the flat target "spacetime" must be associated with either one&#45;time and one&#45;space or at least two&#45;time and two&#45;space coordinates. We discuss the consequences as well as possible applications of our approach on different physical scenarios.</font></p>              <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>Symplectic geometry; constrained Hamiltonian systems; two time physics.</font></p>              <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>              <p align="justify"><font face="verdana" size="2">PACS: 04.20.Gz; 04.60.&#45;Ds; 11.30.Ly</font></p>              <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v59n4/v59n4a11.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a>&nbsp;</font></p>         ]]></body>
<body><![CDATA[<p align="justify">&nbsp;</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 partially supported by PROFAPI&#45;UAS 2009. </font></p> 	         <p align="justify"><font face="verdana" size="2">&nbsp;</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. J.M. Maldacena and H. Ooguri, <i>J. Math. Phys.</i> <b>42</b> (2001) 2929; hep&#45;th/0001053.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8457627&pid=S0035-001X201300040001100001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>          <!-- ref --><p align="justify"><font face="verdana" size="2">2. E. Witten, <i>Phys. Rev. D</i><b>44</b> (1991) 314.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8457629&pid=S0035-001X201300040001100002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>  	    ]]></body>
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