I present results from recent high-order calculations for the production of
electroweak bosons and top quarks. In particular, I discuss $W$ and $Z$ boson
production at large transverse momentum, single-top production, and FCNC top
production. Theoretical predictions which include higher-order soft-gluon
corrections are presented for total cross sections and differential
distributions at the LHC.Comment: 6 pages, 4 figures; presented at the XXIII International Workshop on
  Deep-Inelastic Scattering and Related Subjects, Dallas, Texas, 27 April - 1
  May 2015; to appear in PoS(DIS2015

Kidonakis, Nikolaos

English

arXiv

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Theoretical results for electroweak-boson and single-top production

I present results from recent high-order calculations for the production of electroweak bosons and top quarks. In particular, I discuss W and Z boson production at large transverse momentum, single-top production, and FCNC top production. Theoretical predictions which include higherorder soft-gluon corrections are presented for total cross sections and differential distributions at the LHC

DigitalCommons@Kennesaw State University

Kennesaw State UniversityDigitalCommons@Kennesaw State UniversityFaculty Publications5-1-2015Theoretical Results for Electroweak-boson andSingle-top ProductionNikolaos KidonakisKennesaw State University, nkidonak@kennesaw.eduFollow this and additional works at: https://digitalcommons.kennesaw.edu/facpubsPart of the Physics CommonsThis Article is brought to you for free and open access by DigitalCommons@Kennesaw State University. It has been accepted for inclusion in FacultyPublications by an authorized administrator of DigitalCommons@Kennesaw State University. For more information, please contactdigitalcommons@kennesaw.edu.Recommended CitationKidonakis, Nikolaos, "Theoretical Results for Electroweak-boson and Single-top Production" (2015). Faculty Publications. 3847.https://digitalcommons.kennesaw.edu/facpubs/3847arXiv:1506.04072v1  [hep-ph]  12 Jun 2015Theoretical results for electroweak-boson andsingle-top productionNikolaos Kidonakis∗†Department of Physics, Kennesaw State University, Kennesaw, GA 30144, USAE-mail: nkidonak@kennesaw.eduI present results from recent high-order calculations for the production of electroweak bosons andtop quarks. In particular, I discussW andZ boson production at large transverse momentum,single-top production, and FCNC top production. Theoretical predictions which include higher-order soft-gluon corrections are presented for total crosssections and differential distributions atthe LHC.XXIII International Workshop on Deep Inelastic Scattering27 April - May 1 2015Dallas, Texas∗Speaker.†This material is based upon work supported by the National Science Foundation under Grant No. PHY 1212472.c© Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licen. http://pos.sissa.it/Theoretical results for electroweak-boson and single-top production Nikolaos Kidonakis100 200 300 400 500 600 700 800 900 1000pT (GeV)10-310-210-1100101102dσ/dp T (pb/GeV)aNNLO  µ=pTNLO  µ=pTW-boson pT distribution at the LHC     S1/2=13 and 14 TeV    200 400 600 800 10000.80.911.11.2ratio to NLO µ=p Tratios with µ=pT/2, pT, 2pT          S1/2=14 TeV100 200 300 400 500 600 700 800 900 1000pT (GeV)10-310-210-1100101102dσ/dp T (pb/GeV)aNNLO µ=pTNLO  µ=pTZ-boson pT distribution at the LHC     S1/2=13 and 14 TeV    200 400 600 800 10000.80.911.11.2ratio to NLO µ=p Tratios with µ=pT/2, pT, 2pT       S1/2=14 TeVFigure 1: aNNLOW -boson (left) andZ-boson (right)pT distributions at the LHC.1. IntroductionHigher-order corrections are very significant forW and Z distributions at large transversemomentum,pT , as well as for single-top production cross sections andpT istributions. Soft-gluoncontributions are an important and dominant part of the perturbative corrections.The soft-gluon terms in thenth-order corrections involve logarithms[lnk(s4/p2T )/s4]+ forelectroweak-boson production and[lnk(s4/m2t )/s4]+ for single-top production, withk ≤ 2n−1 ands4 the kinematical distance from partonic threshold. These soft corrections have been resummedat NNLL accuracy via the calculation of the corresponding two-loop soft anomalous dimensions.Approximate NNLO (aNNLO) differential cross sections havebeen derived from the expansion ofthe resummed expressions for electroweak-boson [1,2] and single-top [3–6] production.2. W and Z production at large pTThe production ofW andZ bosons is useful in testing the Standard Model and in estimatesof backgrounds to Higgs production and new physics. The partonic channels at leading order areq(pa)+g(pb)−→W (Q)+q(pc) andq(pa)+ q̄(pb)−→W (Q)+g(pc). We defines = (pa + pb)2,t = (pa −Q)2, u = (pb −Q)2 ands4 = s+ t +u−Q2. At thresholds4 → 0 and the soft correctionsare of the form[lnk(s4/p2T )/s4]+. The latest aNNLO results at NNLL accuracy have been derivedin [1].We begin withW production at largepT . We use MSTW2008 pdf [7] in our calculations. Inthe left plot of Fig. 1 we show the aNNLOW -bosonpT distributions at the LHC at 13 and 14TeV energies. ThepT distributions fall rapidly as thepT of theW boson increases. The inset plotdisplays the ratio of the results to the central NLO result. We observe the significant contributionof the aNNLO corrections and the reduction of scale uncertainty at aNNLO.We continue withZ production at largepT . In the right plot of Fig. 1 we show the aNNLOZ-bosonpT distributions at LHC energies of 13 and 14 TeV. Our observations regarding the size ofthe corrections and the reduction of uncertainty at aNNLO are the same as forW production.2Theoretical results for electroweak-boson and single-top production Nikolaos Kidonakis1 2 3 4 5 6 7 8 9 10 11 12 13 14S1/2 (TeV)1101001000σ (pb)t-channeltW channels-channelATLASCMSATLAS/CMSCDF/D0aNNLO single-top cross sections  +-scale&pdf    mt=172.5 GeV0 100 200 300 400 500pT  top (GeV)10-410-310-210-1100dσ/dp T (pb/GeV)14 TeV13 TeV  8 TeV  7 TeVt-channel top pT distribution at LHC    aNNLO    mt=173.3 GeVFigure 2: (Left) Single-top aNNLO cross sections compared with LHC [8–10, 15–19] and Tevatron [11]data; (Right) aNNLOt-channel toppT distributions at LHC energies.3. Single-top productionSingle-top production can proceed via three partonic channels. At lowest order, thet-channelpartonic processes areqb → q′t andq̄b → q̄′t; thes-channel processes areqq̄′ → b̄t; and the associ-atedtW production processes arebg → tW−, and similarly for single antitop. NNLL resummationfor all these processes was performed in Refs. [3–6].LHC t t̄ Total (pb)8 TeV 55.9+2.1−0.3±1.1 30.6±0.7+0.9−1.1 86.5+2.8−1.0+2.0−2.213 TeV 136+3−1±3 82+2−1±2 218+5−2±514 TeV 154+4−1±3 94+2−1+2−3 248+6−2+5−6Table 1: aNNLO single-top and single-antitopt-channel cross sections withmt = 173.3 GeV.In Table 1 we show the single-top and single-antitop-channel production cross sections ataNNLO at the LHC, as well as the total sum of the two. The first uncertainty is from scale variationover mt/2 ≤ µ ≤ 2mt while the second is from pdf errors with MSTW2008 NNLO pdf at 90%C.L. [7].In the left plot of Fig. 2 we plot thet-channel total cross section as a function of collider energy.At 7 TeV LHC energy, we compare witht-channel data from ATLAS [8] and CMS [9]. At 8 TeVLHC energy we compare with ATLAS/CMS combinationt-channel data [10]. Finally, at 1.96Tevatron energy we compare with CDF/D0 combination data [11]. We find excellent agreement oftheory with data for all collider energies.The aNNLO ratioσ(t)/σ(t̄) = 1.82+0.10−0.09 at 8 TeV which compares very well with the CMSresult 1.95±0.10±0.19 [12]. It is also in excellent agreement with the NNLO result in [13].We continue witht-channel aNNLOpT distributions [14]. In the right plot of Fig. 2 we displaythe toppT distributions int-channel production at various LHC energies.In Fig. 3 we display the top and antitoppT distributions in single-topt-channel production at7 TeV LHC energy and compare with ATLAS data [8], finding good overall agreement.3Theoretical results for electroweak-boson and single-top production Nikolaos Kidonakis0 50 100 150 200pT  top (GeV)0.00.20.40.6dσ/dp T (pb/GeV)7 TeV+ ATLASt-channel top pT distribution at LHC    aNNLO    mt=172.5 GeV0 50 100 150 200pT  antitop (GeV)0.00.10.20.30.4dσ/dp T (pb/GeV)7 TeV+ ATLASt-channel antitop pT distribution at LHC    aNNLO    mt=172.5 GeVFigure 3: Top (left) and antitop (right)pT distributions int-channel production at 7 TeV LHC energycompared with ATLAS data [8].LHC t t̄ Total (pb)8 TeV 3.75±0.07±0.13 1.90±0.01±0.08 5.65±0.08±0.2113 TeV 7.07±0.13+0.24−0.22 4.10±0.05+0.14−0.16 11.17±0.18±0.3814 TeV 7.79±0.14+0.31−0.24 4.57±0.05+0.18−0.17 12.35±0.19+0.49−0.41Table 2: aNNLO single-top and single-antitops-channel cross sections withmt = 173.3 GeV.Next we discusss-channel production at the LHC. In Table 2 we show the single-top andsingle-antitops-channel production cross sections at aNNLO at the LHC, as well as the total sumof the two. The first uncertainty is again from scale variation while the second is from pdf errorswith MSTW2008 NNLO pdf at 90% C.L. [7].In the left plot of Fig. 2 we plot thes-channel total cross section as a function of colliderenergy. At 8 TeV LHC energy we compare with data from ATLAS [15] and CMS [16]. The datafrom both experiments have much larger uncertainties than te theoretical prediction but are inexcellent agreement with it.In the left plot of Fig. 4 we display new aNNLO results for the top pT distributions ins-channelproduction at LHC energies.LHC tW− tW−+ t̄W+ (pb)8 TeV 11.0±0.3±0.7 22.0±0.6±1.413 TeV 35.20±0.9+1.6−1.7 70.40±1.8+3.2−3.414 TeV 41.6±1.0+1.5−2.3 83.1±2.0+3.1−4.6Table 3: aNNLO tW cross sections withmt = 173.3 GeV.We continue with associatedtW production at aNNLO at the LHC. In Table 3 we show theWproduction cross sections at aNNLO at the LHC. The first uncertainty is again from scale variationwhile the second is from MSTW2008 [7] pdf errors.4Theoretical results for electroweak-boson and single-top production Nikolaos Kidonakis0 100 200 300 400 500pT  top (GeV)10-410-310-210-1dσ/dp T (pb/GeV)14 TeV13 TeV  8 TeV  7 TeVs-channel top pT distribution at LHC    aNNLO    mt=173.3 GeV0 100 200 300 400 500pT  top (GeV)10-410-310-210-1dσ/dp T (pb/GeV)14 TeV13 TeV  8 TeV  7 TeVTop pT distribution in tW- production at  LHC    aNNLO   mt=173.3 GeVFigure 4: Top pT distributions in single-tops-channel production (left) and intW− production (right).In the left plot of Fig. 2 we plot thetW total cross section as a function of collider energy.At 7 TeV LHC energy, we compare withtW data from ATLAS [17] and CMS [18]. At 8 TeVLHC energy we compare with ATLAS/CMS combination data [19].We find excellent agreementof theory with data for both LHC energies. In the right plot ofFig. 4 we display the top-quarkpTdistributions intW− production at LHC energies.4. FCNC top productionFinally, we consider FCNC top-quark production via anomalous gluon couplings. The partonicprocesses are of the formgu → tg which involvet-u-g couplings. We considered these processesbeyond leading order and calculated the soft-gluon corrections at NLL accuracy in [20].The ratio of the LO and aNLO cross sections at various choice scale to the LO result withµ = mt was shown in [20] at both 7 and 14 TeV LHC energies. It was foundthat the NLO soft-gluon corrections are large and they reduce the scale dependnce of the cross section. At bothenergies the NLO soft-gluon corrections increase the LO cross section by around 60% forµ = mt .The reduction in scale variation overmt/2≤ µ ≤ 2mt is also very significant.5. SummaryWe have presented results for NNLL soft-gluon corrections for electroweak-boson and single-top production. The aNNLO corrections are significant at theLHC and the Tevatron. There isexcellent agreement for single-top production with LHC andTevatron data in all channels. Futurework will extend these results to more differential distribut ons and aN3LO.References[1] N. Kidonakis and R.J. Gonsalves,NNLO soft-gluon corrections for the Z-boson and W -bosontransverse momentum distributions, Phys. Rev. D 89, 094022 (2014) [arXiv:1404.4302 [hep-ph]].[2] N. Kidonakis and R.J. Gonsalves,Higher-order QCD corrections for the W-boson transversemomentum distribution, Phys. Rev. D 87, 014001 (2013) [arXiv:1201.5265 [hep-ph]].5Theoretical results for electroweak-boson and single-top production Nikolaos Kidonakis[3] N. Kidonakis,Next-to-next-to-leading-order collinear and soft gluon corrections for t-channel singletop quark production, Phys. Rev. D 83, 091503(R) (2011) [arXiv:1103.2792 [hep-ph]].[4] N. Kidonakis,NNLL resummation for s-channel single top quark production, Phys. Rev. D 81, 054028(2010) [arXiv:1001.5034 [hep-ph]].[5] N. Kidonakis,Two-loop soft anomalous dimensions for single top quark associated production with aW− or H−, Phys. Rev. D 82, 054018 (2010) [arXiv:1005.4451 [hep-ph]].[6] N. Kidonakis,NNLL threshold resummation for top-pair and single-top production, Phys. Part. Nucl.45, 714 (2014) [arXiv:1210.7813 [hep-ph]].[7] A.D. Martin, W.J. Stirling, R.S. Thorne, and G. Watt,Parton distributions for the LHC, Eur. Phys. J.C 63, 189 (2009) [arXiv:0901.0002 [hep-ph]].[8] ATLAS Collaboration,Comprehensive measurements of t-channel single top-quark production crosssections at√s = 7 TeV with the ATLAS detector, Phys. Rev. D 90, 112006 (2014) [arXiv:1406.7844[hep-ex]].[9] CMS Collaboration,Measurement of the single-top-quark t-channel cross section in pp collisions at√s = 7 TeV, JHEP 12, 035 (2012) [arXiv:1209.4533 [hep-ex]].[10] ATLAS and CMS Collaborations,Combination of single top-quark cross-sections measurements inthe t-channel at√s = 8 TeV with the ATLAS and CMS experiments, ATLAS-CONF-2013-098,CMS-PAS-TOP-12-002.[11] CDF and D0 Collaborations,Tevatron combination of single-top-quark cross sections anddetermination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element Vtb,arXiv:1503.05027 [hep-ex].[12] CMS Collaboration,Measurement of the t-channel single-top-quark production cross section and ofthe |Vtb| CKM matrix element in pp collisions at√s = 8 TeV, JHEP 06, 090 (2014) [arXiv:1403.7366[hep-ex]].[13] M. Brucherseifer, F. Caola, and K. Melnikov,On the NNLO QCD corrections to single-top productionat the LHC, Phys. Lett. B 736, 58 (2014) [arXiv:1404.7116 [hep-ph]].[14] N. Kidonakis,Top-quark transverse-momentum distributions in t-channel single-top production,Phys. Rev. D 88, 031504(R) (2013) [arXiv:1306.3592 [hep-ph]].[15] ATLAS Collaboration,Search for s-channel single top-quark production in proton-proton collisionsat√s = 8 TeV with the ATLAS detector, Phys. Lett. B 740, 118 (2015) [arXiv:1410.0647 [hep-ex]].[16] CMS Collaboration,Measurement of the single top s-channel cross section at 8 TeV,CMS-PAS-TOP-13-009.[17] ATLAS Collaboration,Evidence for the associated production of a W boson and a top quark inATLAS at√s = 7 TeV, Phys. Lett. B 716, 142 (2012) [arXiv:1205.5764 [hep-ex]].[18] CMS Collaboration,Evidence for associated production of a single top quark and W boson in ppcollisions at√s = 7 TeV, Phys. Rev. Lett. 110, 022003 (2013) [arXiv:1209.3489 [hep-ex]].[19] ATLAS and CMS Collaborations,Combination of cross-section measurements for associatedproduction of a single top-quark and a W boson at√s = 8 TeV with the ATLAS and CMSexperiments, ATLAS-CONF-2014-052, CMS-PAS-TOP-14-009.[20] N. Kidonakis and E. Martin,Soft-Gluon Corrections in FCNC Top-Quark Production via AnomalousGluon Couplings, Phys. Rev. D 90, 054021 (2014) [arXiv:1404.7488 [hep-ph]].6

Theoretical Results for Electroweak-boson and Single-top Production

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Theoretical results for electroweak-boson and single-top production

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