Physics teams measure eta meson production in high-energy collisions
Researchers have made the first direct measurements of eta meson production rates in proton collisions at near-record energies, filling a critical gap in particle physics data. The findings help validate theoretical models used across nuclear research and could refine understanding of how fundamental particles behave under extreme conditions.
Originaltitel: Cross sections of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>η</mml:mi> </mml:math> mesons in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>p</mml:mi> <mml:mo>+</mml:mo> <mml:mi>p</mml:mi> </mml:math> collisions at forward rapidity at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>500</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>GeV</mml:mi> </mml:math> and central rapidity at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>510</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>GeV</mml:mi> </mml:math>
We present the first measurements of the forward and midrapidity <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>η</a:mi> </a:math> -meson cross sections from <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>p</c:mi> <c:mo>+</c:mo> <c:mi>p</c:mi> </c:math> collisions at <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msqrt> <e:mi>s</e:mi> </e:msqrt> <e:mo>=</e:mo> <e:mn>500</e:mn> </e:math> and 510 GeV, respectively. We also report the midrapidity <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>η</g:mi> <g:mo>/</g:mo> <g:msup> <g:mi>π</g:mi> <g:mn>0</g:mn> </g:msup> </g:math> ratio at 510 GeV. The forward cross section is measured differentially in <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mi>η</i:mi> </i:math> -meson transverse momentum ( <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:msub> <k:mi>p</k:mi> <k:mi>T</k:mi> </k:msub> </k:math> ) from 1.0 to <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mrow> <m:mn>6.5</m:mn> <m:mtext> </m:mtext> <m:mtext> </m:mtext> <m:mi>GeV</m:mi> <m:mo>/</m:mo> <m:mi>c</m:mi> </m:mrow> </m:math> for pseudorapidity <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mn>3.0</o:mn> <o:mo><</o:mo> <o:mo stretchy="false">|</o:mo> <o:mi>η</o:mi> <o:mo stretchy="false">|</o:mo> <o:mo><</o:mo> <o:mn>3.8</o:mn> </o:math> . The midrapidity cross section is measured from 3.5 to <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:mrow> <s:mn>44</s:mn> <s:mtext> </s:mtext> <s:mtext> </s:mtext> <s:mi>GeV</s:mi> <s:mo>/</s:mo> <s:mi>c</s:mi> </s:mrow> </s:math> for pseudorapidity <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"> <u:mo stretchy="false">|</u:mo> <u:mi>η</u:mi> <u:mo stretchy="false">|</u:mo> <u:mo><</u:mo> <u:mn>0.35</u:mn> </u:math> . Both cross sections serve as critical inputs to an updated global analysis of the <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"> <y:mi>η</y:mi> </y:math> -meson fragmentation functions.