Development and validation of HERWIG 7 tunes from CMS underlying-event measurements
A. M. Sirunyan, A. Tumasyan, W. Adam, F. Ambrogi, T. Bergauer, M. Dragicevic, J. Erö, A. Escalante Del Valle, R. Frühwirth, M. Jeitler, Natascha Krammer, L. Lechner, D. Liko, T. Madlener, I. Mikulec, F. M. Pitters, N. Rad, J. Schieck, R. Schöfbeck, Markus Spanring, S. Templ, W. Waltenberger, C.-E. Wulz, M. Zarucki, V. Chekhovsky, A. Litomin, В. Макаренко, J. Suarez Gonzalez, M. R. Darwish, E. Wolf, D. Di Croce, X. Janssen, T. Kello, A. Lelek, M. Pieters, Haifa Rejeb Sfar, Hans Van Haevermaet, P. Van Mechelen, S. Van Putte, N. Van Remortel, F. Blekman, E. S. Bols, S. S. Chhibra, J. D’Hondt, J. De Clercq, D. Lontkovskyi, S. Lowette, I. Marchesini, S. Moortgat, A. Morton, Q. Python, S. Tavernier, W. Van Doninck, P. Van Mulders, D. Beghin, B. Bilin, B. Clerbaux, G. De Lentdecker, H. Delannoy, B. Dorney, L. Favart, A. Grebenyuk, A. K. Kalsi, I. Makarenko, L. Moureaux, L. Pétré, A. Popov, N. Postiau, E. Starling, Laurent Thomas, C. Vander Velde, P. Vanlaer, D. Vannerom, Liam Wezenbeek, T. Cornelis, D. Dobur, Marek Gruchala, I. Khvastunov, M. Niedziela, C. Roskas, K. Skovpen, M. Tytgat, W. Verbeke, B. Vermassen, Martina Vit, G. Bruno, F. Bury, C. Caputo, P. David, C. Delaere, M. Delcourt, I. S. Donertas, A. Giammanco, V. Lemaı̂tre, K. Mondal, Jessica Prisciandaro, A Taliercio, M. Teklishyn, P. Vischia, S. Wuyckens
Abstract
Abstract This paper presents new sets of parameters (“tunes”) for the underlying-event model of the $${\textsc {herwig}} \,7$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mstyle> <mml:mi>H</mml:mi> <mml:mi>E</mml:mi> <mml:mi>R</mml:mi> <mml:mi>W</mml:mi> <mml:mi>I</mml:mi> <mml:mi>G</mml:mi> </mml:mstyle> <mml:mspace/> <mml:mn>7</mml:mn> </mml:mrow> </mml:math> event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in $${\textsc {herwig}} \,7$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mstyle> <mml:mi>H</mml:mi> <mml:mi>E</mml:mi> <mml:mi>R</mml:mi> <mml:mi>W</mml:mi> <mml:mi>I</mml:mi> <mml:mi>G</mml:mi> </mml:mstyle> <mml:mspace/> <mml:mn>7</mml:mn> </mml:mrow> </mml:math> , and are obtained from a fit to minimum-bias data collected by the CMS experiment at $$\sqrt{s}=0.9$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>0.9</mml:mn> </mml:mrow> </mml:math> , 7, and $$13 \,\text {Te}\text {V} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>13</mml:mn> <mml:mspace/> <mml:mrow> <mml:mtext>Te</mml:mtext> <mml:mspace/> </mml:mrow> </mml:mrow> </mml:math> . The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the data.