Title Measurement of the underlying event activity at the LHC with $\sqrt{s}$ = 7 TeV and comparison with $\sqrt{s}$ = 09 TeV Author Chatrchyan, S. Khachatryan, V. Sirunyan, A. M. Bansal, S. de Wolf, E.A. Janssen, X. Mucibello, L. Roland, B. Rougny, R. Selvaggi, M. van Haevermaet, H. Van Mechelen, P. Van Remortel, N. et al. Faculty/Department Faculty of Sciences. Physics Publication type article Publication 2011 Bristol , 2011 Subject Physics Source (journal) Journal of high energy physics. - Bristol Volume/pages (2011) :9 , p. 1-31 ISSN 1126-6708 1029-8479 ISI 000296086700034 Carrier E-only publicatie Target language English (eng) Full text (Publishers DOI) Affiliation University of Antwerp Abstract A measurement of the underlying activity in events with a jet of transverse momentum in the several GeV region is performed in proton-proton collisions at s=09 and 7 TeV, using data collected by the CMS experiment at the LHC. The production of charged particles with pseudorapidity |η| < 2 and transverse momentum p T  > 0.5 GeV/c is studied in the azimuthal region transverse to that of the leading set of charged particles forming a track-jet. A significant growth of the average multiplicity and scalar-p T sum of the particles in the transverse region is observed with increasing p T of the leading track-jet, followed by a much slower rise above a few GeV/c. For track-jet p T larger than a few GeV/c, the activity in the transverse region is approximately doubled with a centre-of-mass energy increase from 0.9 to 7 TeV. Predictions of several QCD-inspired models as implemented in pythia are compared to the data. Full text (open access) https://repository.uantwerpen.be/docman/irua/257b45/d8c4e1d6.pdf E-info http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000296086700034&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848 http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000296086700034&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848 http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000296086700034&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848 Handle