<?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>S0035-001X2016000300235</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Reduction of the Salpeter equation for massless constituents]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Chen]]></surname>
<given-names><![CDATA[Jiao-Kai]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Shanxi Normal University  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>China</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2016</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2016</year>
</pub-date>
<volume>62</volume>
<numero>3</numero>
<fpage>235</fpage>
<lpage>239</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2016000300235&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2016000300235&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2016000300235&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Different from the case of the limit, it is shown in this paper that in the ultrarelativistic limit, the L = j, j+1 wave components are large terms for both state with parity &#544;P = (-1)j and state with parity &#544;P = (-1)j+1. Moreover, it is found that the states with parity &#544;P = (-1) j are degenerate with the states with parity &#544;P = (-1) j +1 if the Lorentz structure of the interaction between the massless constituents is four-vector or time-component of four-vector. The scalar interaction violates this degeneracy.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Ultrarelativistic limit]]></kwd>
<kwd lng="en"><![CDATA[Salpeter equation, different states]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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