Impact of QCD and PDF uncertaintjes on Standard Model Measurements - PowerPoint PPT Presentation

Impact of QCD and PDF uncertaintjes on Standard Model Measurements a theory heory/PD PDF a ana nalysi sis p s per ersp spectjv ectjve. e. Tim Hobbs, SMU/CTEQ and JLab EIC Center July 17 th 2019 Collaboratjon with Bo-Ting g Wang, Pavel N el Nadols lsky, Fred O Oln lness …and CTEQ-TEA… July 17 th 2019 QCD@LHC ‘19. Bufgalo, NY; July 15-19, 2019. QCD@LHC ‘19. Bufgalo, NY; July 15-19, 2019.

LHC C has has ac accumulated cop opious ious hi high- h-precis ision ion data ta “data a deluge...” this data is an opportunity, but also a challenge: → PDF uncertaintjes are a doub ouble- le-ed edged ed sw sword (i.e., quantjtjes for which PDF uncertaintjes are large are also PDF-sensitjve, and can be constraining) this talk (mainly): → to reach precision objectjves for HL-LHC, it will be crucial to understand pulls/tensions in modern PDF analyses 2

3

understanding LHC implicatjons for PDF fjts (and vice versa) LHC Run-1 data drive important PDF improvements, including for the gluon at high-, low- x BUT BUT: p per erforming/ ming/comp mparing ing fjt fjts is is insuffj ffjcien ent for und understandin ing P g PDF DF sensitjv tjvitje tjes 4

: an impact-study framework complementary to P D F S e n s e reweighing approaches (See e talk by C. Schmidt.) P U M P qui uickly evaluate a HEP data set according to its PDF sens nsitj tjvity, ("correl elatj tjon n 2.0 .0"): an easy-to-compute fj fjgu gure- e-of-mer merit it for data point sensitjvity to PDFs in the presence of experimental errors map these sensitjvitjes in a kinematjcal parameter space to map these sensitjvitjes in a kinematjcal parameter space to quantjfy/visualize origin and interplay of pulls and tensions quantjfy/visualize origin and interplay of pulls and tensions an n expanding ing set of calculatjons tjons: 1. . Mapping ing t the sens ensitj itjvit ity o of h hadronic e experimen iments t to n nucleo eon s n structure B.-T. Wang, T.J. Hobbs, S. Doyle, J. Gao, T.-J. Hou, P. M. Nadolsky, F. I. Olness Phys.R .Rev. D9 . D98 ( (2018) 0 094030 T O 2. . The c e comin ming s g syner nergy gy b betwee een la lattjc ttjce Q QCD and h high igh-ener energy gy p phenomeno menolo logy D T.J. Hobbs, Bo-Ting Wang, Pavel Nadolsky, Fredrick Olness A arXiv:1904.0 .00222 Y 3. . Mapping ing t the PDF PDF s sens ensitj itjvit ity o of futur ure f e facil cilitj itjes es ( (HL-LHC, LH LHeC, a and E EIC IC) T.J. Hobbs, Bo-Ting Wang, Pavel Nadolsky, Fredrick Olness arxiv iv:1907.0 .00988 (more detailed work in preparatjon) 5

6

guided the selectjon and implementatjon of these data P D F S e n s e for CT18 7

ho how i is t s thi his d s done one? … examine and map the sensitjvitjes based on knowledge of Hessian PD PDFs and resi esidua ual variatjons ● idea : study the statjs tjstjc tjcal correlatjon tjon between PDFs and the quality of the fjt at a measured data point(s); fjt quality encoded in a (T heory ) – ( shifued D ata ) residual : ● for each data point, calculate the correlatjon (and sensitjvity) between the residual and PDFs based on Hessian variatjon over PDF replicas, ● map these in kinematjcal parameter space where, e.g., for DIS, 8

9

the sensitivity reveals a richer landscape than the correlation! e.g., the substantjal impact of inclusive jet data on gluon PDF is identjfjed by sens nsitjv tjvity maps reveal: (i) highest impact data points for specifjc PDFs/observables (ii) tensions/complementaritjes among data sets (iii) physical origin of PDF constraints 10

CM CMS jet jets ● heavy quark HERA production proceeds through boson fusion diagrams: BCD BCDMS, CCFR CCFR charm sensitivities closely track the gluon plot 11

[arXiv:1803.02777] 12

we use this technology to examine imp implic icatjo tjons ns for HEP EP phe henome menology gy at t LHC esp., EW EW p phen heno., H Hig iggs s physics ics, g g(x) (x), … Mapping ing t the sensitj itjvity o of h hadronic e ic exper erimen iments t to n nucl ucleo eon n structure B.-T. Wang, T.J. Hobbs, S. Doyle, J. Gao, T.-J. Hou, P. M. Nadolsky, F. I. Olness Phys.R .Rev. D9 . D98 ( (2018) 0 094030 L2 sensitjvity details in The c e coming s g synergy b between la en lattjc ttjce QCD and high high-ener energy gy p pheno enomeno menolo logy gy T.J. Hobbs, Bo-Ting Wang, Pavel Nadolsky, Fredrick Olness arXiv iv:1904.0 .00222v2 (coming soon) 13

14

…as a follow-on to Alesandro’s EW-focused overview: important PDF correlatjons for the ATLAS extractjon of It is instructjve to explore the data pulls on 15

PDF sensitjvity of from 7 TeV ATLAS data CT14N 14NNL NLO CTEQ-TEA sensitjvitjes to 16

17

rather than the costly LM scans, we can examine a “cheaper” measure which yields comparable informatjon the L2 sensitjvity or, 18 …extent to which total χ 2 E of specifjc expts. correlates with x -dep. of PDFs

strong onger (antj tj-)correlatjon tjon tension between LHCb W/Z data (245, 250); fjxed-target DIS, Drell-Yan (CDHSW F 3 [109], E866pp [204]) strong ong corr. 19

tension between LHCb W/Z data (245, 250); fjxed-target DIS, Drell-Yan (CDHSW F 3 [109], E866pp [204]) again, tensions observed between, e.g., NMC ratjo strong ong corr. data and CDHSW, E866pp 20

…this analysis can be extended to M W , extractjons of which are dependent upon s(x), through Z-calibratjon corr. 21

corr. 22

corr. pronoun unced ed e efg fgect ect o of ATLAS 7 TeV Z Z/W 23 data!

Higgs, g(x) σ H crucially limited by PDF and α S uncertaintjes ● there remains considerable dependence (as large as ~13%) upon PDF paramatrization and running coupling → the situation is such that precision in Higgs phenom. is significantly PDF-limited Accardi et al., EPJC 76 , 471 (2016). → enhancing the discovery potential in the Higgs sector will require improving these uncertainties! 24

CT14 → CT18 modestly shifus Higgs cross sectjons and slightly reduces PDF uncertaintjes can we disentangle elements of the global analysis responsible for these improvements? 25

● afuer the aggregated HERA data, incl nclus usive j e jet et prod oductj uctjon on have greatest total sensitjvity! large correlatjons for E86 866, BCDMS, CCFR FR, CMS S WAS ASY, Z p T and tub tubar ar productjon, but smaller numbers of highly-sensitjve points 26

we use the Higgs region g(x) to validate P D F S e n s e …for the gluon PDF in the Higgs region, ● PDFSense identjfjes the most sensitjve experiments with high confjdence and in accord with other methods such as the LM scans. It works the best when the uncertaintjes are nearly Gaussian, and experimental constraints agree among themselves [arXiv:1803.02777] 27

28

29

30

(a a conse sequ quence of usi using ng a a "sa saturatj tjon" fac actorizatj tjon scale in n NN NNLO DIS S for CT18 18Z) 31

BSM (?) more speculatjvely, BSM searches and SMEFT represent possibilitjes for analogous sensitjvity analyses ● SMEFiT analyses fjt a generic parametrizatjon of BSM physics, e.g., van Beek, Nocera, Rojo, Slade, arXiv:1906.05296 dependent upon Wilson coffjcients for dim-6 operators: with error replicas in the space of {c i (k) } , one could analyze data pulls on SMEFiT ingredients à la P D F S e n s e 32

the future: towa ward precision on PDFs a systematjc approach to reconcile LHC experiments will be imperatjve to reducing PDF uncertaintjes for the precision EW era at HL HL-LHC HC CT14 HERA2 NN NNLO ● very high luminosity DIS colliders, like the electron- ion collider (EIC) at JLab/BNL or LHeC could provide a new generatjon of very precise data in the fjxed-target region ‘cleaner’ leptonic probes free of nuclear efgects OR, understand nuclear medium (for CCFR, NuTeV, ...) 33

conclud cluding o observ ervatj tjons ons produces kinematjc maps and summary charts of data-point ● P D F S e n s e sensitjvitjes to PDFs and PDF-dependent quantjtjes; readily extendable fast; pub ublic code: : htup:/ /metapdf.hepforge.org/PDFSense ● PDF uncertaintjes of HEP observables can be opportuntjes for sensitjve PDF measurements ● heightened constraining power (on sin 2 θ W , σ H , …) will require smoothing data tensions that are now being explored sin 2 θ W driven by u val , d val , which, e.g., E866pp, BCDMS have opposing pulls a commu munity efg efgort t to und nder erstand nd s systema ematj tjc c tensions nee needed ed we fjnd important improvements σ H from incl. jet prod.; resolutjon of tensions will further tjghten constraints ● dealing with these issues will be essentjal for HL-LHC program TH THAN ANKS KS!! 34

supplemental material

CM CMS jet jets relatively ± (PDF) r i large at high and low x for the gluon distribution ● measurements at high/low x are therefore most sensitive; esp. Run 2 HERA HERA points and CMS jet production at BCDMS, CCF BC CCFR 7, 8 TeV 11

33

34

PDF sensitjvity of