New herwig7 underlying event tune: From RHIC to LHC energies

We present parameter sets corresponding to new underlying event tunes for the erwig7.3 Monte Carlo event generator. The existing erwig tunes are in good agreement with LHC data, however, they are not typically designed for center-of-mass energies below <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msqrt> <a:mi>s</a:mi> </a:msqrt> <a:mo>=</a:mo> <a:mn>300</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:mi>GeV</a:mi> </a:math> . The tunes presented in this study can describe midrapidity data collected at the nominal RHIC energy of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msqrt> <c:mi>s</c:mi> </c:msqrt> <c:mo>=</c:mo> <c:mn>200</c:mn> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:mi>GeV</c:mi> </c:math> as well as higher center-of-mass energies utilized by experiments at the LHC and Tevatron. The base “New Haven” tune is developed by fitting minimum-bias simulations of proton-proton ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>p</e:mi> <e:mi>p</e:mi> </e:math> ) collisions to midrapidity identified hadron and jet data from the STAR experiment. The “Nashville” tune includes a separate set of parameters developed by tuning to Tevatron proton-antiproton ( <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>p</g:mi> <g:mover accent="true"> <g:mi>p</g:mi> <g:mo stretchy="false">¯</g:mo> </g:mover> </g:math> ) data at <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:msqrt> <k:mi>s</k:mi> </k:msqrt> <k:mo>=</k:mo> <k:mn>300</k:mn> </k:math> , 900 and 1960 GeV from CDF, and LHC <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mi>p</m:mi> <m:mi>p</m:mi> </m:math> measurements from CMS at <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:msqrt> <o:mi>s</o:mi> </o:msqrt> <o:mo>=</o:mo> <o:mn>7</o:mn> <o:mtext> </o:mtext> <o:mtext> </o:mtext> <o:mi>TeV</o:mi> </o:math> , in addition to the STAR measurements. Both new tunes demonstrate significant improvements over the recommended default tune currently included in the latest version of erwig for minimum bias production. As such, we advocate using these tunes for future simulation studies at midrapidity by experimental collaborations at RHIC (STAR and sPHENIX) and the LHC (ALICE, ATLAS, and CMS).