<?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>S0035-001X2006001000014</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Time dependent problems in relativistic quantum mechanics]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Moshinsky]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Sadurní]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Física ]]></institution>
<addr-line><![CDATA[México D.F.]]></addr-line>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>11</month>
<year>2006</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>11</month>
<year>2006</year>
</pub-date>
<volume>52</volume>
<fpage>74</fpage>
<lpage>76</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2006001000014&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2006001000014&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2006001000014&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[The most effective procedure for dealing with time dependent problems is through the Feynman propagator. In this note we indicate the explicit expression for this propagator in relativistic problems using spectral decomposition. We then take as an initial state one of a Dirac oscillator and consider the behaviour of the wave function when the interaction is suddenly supressed.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[La manera mas efectiva para analizar problemas dependientes del tiempo en mecánica cuántica es a través del propagador de Feynman. En esta nota indicamos la forma explícita de este propagador en problemas relativistas, usando la decomposición espectral. Posteriormente tomamos un estado del oscilador de Dirac como condición inicial y estudiamos el comportamiento de la función de onda cuando la interacción desaperece repentinamente.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Transient phenomena]]></kwd>
<kwd lng="en"><![CDATA[propagators]]></kwd>
<kwd lng="en"><![CDATA[wave functions]]></kwd>
<kwd lng="es"><![CDATA[Fenómenos transitorios]]></kwd>
<kwd lng="es"><![CDATA[propagadores]]></kwd>
<kwd lng="es"><![CDATA[funciones de onda]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="center"><font face="verdana" size="4"><b>Time dependent problems in relativistic quantum mechanics</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>M. Moshinsky* and E. Sadurn&iacute;</b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>Instituto de F&iacute;sica, Universidad Nacional Aut&oacute;noma de M&eacute;xico, </i><i>Apartado Postal 20&#150;364, 01000 M&eacute;xico, D.F.,     <br> e&#150;mail: <a href="mailto:moshi@fisica.unam.mx" target="_blank">moshi@fisica.unam.mx</a>, <a href="mailto:sadurni@fisica.unam.mx" target="_blank">sadurni@fisica.unam.mx</a></i></font></p>     <p align="justify"><font face="verdana" size="2"><i>* </i>Member of El Colegio Nacional and Sistema Nacional de Investigadores.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Recibido el 3 de enero de 2006    <br> Aceptado el 6 de abril de 2006</font></p>     ]]></body>
<body><![CDATA[<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">The most effective procedure for dealing with time dependent problems is through the Feynman propagator. In this note we indicate the explicit expression for this propagator in relativistic problems using spectral decomposition. We then take as an initial state one of a Dirac oscillator and consider the behaviour of the wave function when the interaction is suddenly supressed.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>Transient phenomena; propagators; wave functions.</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">La manera mas efectiva para analizar problemas dependientes del tiempo en mec&aacute;nica cu&aacute;ntica es a trav&eacute;s del propagador de Feynman. En esta nota indicamos la forma expl&iacute;cita de este propagador en problemas relativistas, usando la decomposici&oacute;n espectral. Posteriormente tomamos un estado del oscilador de Dirac como condici&oacute;n inicial y estudiamos el comportamiento de la funci&oacute;n de onda cuando la interacci&oacute;n desaperece repentinamente.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Descriptores: </b>Fen&oacute;menos transitorios; propagadores; funciones de onda. </font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">PACS: 03.65.Ge</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v52s4/v52s4a14.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>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. J.J. Sakurai, <i>Modern Quantum Mechanics </i>(Addison Wesley, 1995).</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=8329246&pid=S0035-001X200600100001400001&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. A. Messiah, <i>Quantum Mechanics </i>(Dover, New York, 1999).</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=8329247&pid=S0035-001X200600100001400002&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. Moshinsky and A. Szczepaniak, <i>J. Phys. A: Math. Gen. </i><b>22</b> (1989) L817.</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=8329248&pid=S0035-001X200600100001400003&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. Radoslaw Szmytkowski <i>et al., J. Phys. A: Math. Gen. </i><b>34</b> (2001) 4991.</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=8329249&pid=S0035-001X200600100001400004&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. Gradshteyn and Ryzhik, Table of integrals, series and products (Academic Press).</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=8329250&pid=S0035-001X200600100001400005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> ]]></body><back>
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