PDF constraints from! recent LHCb data

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1 PDF constraints from recent LHCb data Juan Rojo VU Amsterdam & Theory group, Nikhef LHCb Electroweak, Top & Jets Joint Meeting 3/0/07 Juan Rojo LHCb EW meeting, 3/0/07

2 ) [ref] ) / g ( x, Q g ( x, Q Global no Z pt data No top data No jet data 4 NNLO, Q = GeV 0.9 x NNPDF3. NNLO, Q=.65 GeV.6 NNPDF3.0 NNPDF3. global.4 NNPDF3. collider ) ( x, Q R S. 0.8 NNPDF Collaboration In preparation x Juan Rojo LHCb EW meeting, 3/0/07

3 New datasets in NNPDF3. Measurement Data taking Motivation Combined HERA inclusive data Run I+II quark singlet and gluon D0 legacy W asymmetries Run II quark flavor separation ATLAS inclusive W, Z rap 7 TeV 0 strangeness ATLAS inclusive jets 7 TeV 0 large-x gluon ATLAS low-mass Drell-Yan 7 TeV 0+0 small-x quarks ATLAS Z pt 7,8 TeV 0+0 medium-x gluon and quarks ATLAS and CMS tt differential 8 TeV 0 large-x gluon CMS Z (pt,y) D xsecs 8 TeV 0 medium-x gluon and quarks CMS Drell-Yan low+high mass 8 TeV 0 small-x and large-x quarks CMS W asymmetry 8 TeV 0 quark flavor separation CMS 8.76 TeV jets 0 medium and large-x gluon LHCb W,Z rapidity dists 7 TeV 0 large-x quarks LHCb W,Z rapidity dists 8 TeV 0 large-x quarks 3 Juan Rojo LHCb EW meeting, 3/0/07

4 NNPDF3.: fit settings PDF evolution and DIS structure functions up to NNLO are computed with APFEL in the FONLL GM- VFN scheme Hadronic data included using APPLgrid/FastNLO interfaced to supplemented by bin-by-bin NNLO/NLO K-factors obtained separately for each specific process The APFELgrid tool is used to combine a priori PDF evolution with applgrid interpolated coefficient functions, achieving an speed-up by up to three orders of magnitude for the evaluation of hadronic cross-sections during the PDF fit 4 Juan Rojo LHCb EW meeting, 3/0/07

5 Fitted vs Perturbative charm The change of scheme between a theory with 3 active quarks and another with determined by the matching conditions: 4 active quarks is Most global fits (including NNPDF3.0) assume that c (3) (x)=0, in other words, the scale-independent (intrinsic) charm content of the proton vanishes Whether or not c (3) (x)=0 is a good assumption can only be determined from data Releasing this assumption leads to the modified matching conditions Scale-independent (intrinsic) charm Scale-dependent charm PDF: to be determined from data at Q 0 >m c Perturbative contribution from charm-anticharm radiation off gluons 5 NNPDF3. fits obtained both for a fitted and for a perturbative charm PDF Juan Rojo LHCb EW meeting, 3/0/07

6 Forward W,Z production at LHCb NNPDF3. includes the complete 7 TeV and 8 TeV W,Z measurements in the muon channel, as well as most of the electron channel measurements Crucial to account for the cross-correlations between the W and Z data Expect improved quark-flavor separation for large-x quarks, thanks to LHCb forward kinematics Complementary information to that from W, Z production from ATLAS and CMS 6 Juan Rojo LHCb EW meeting, 3/0/07

7 Forward W,Z production at LHCb NNPDF3. 7 Improved agreement as compared to NNPDF3.0, specially in the forward region Significant reduction of PDF uncertainties wrt to NNPDF3.0, by almost factor NNLO QCD does not describe the most central bin of the 8 TeV W data: excluded from fit Juan Rojo LHCb EW meeting, 3/0/07

8 Forward W,Z production at LHCb NNPDF3. For Z production, also improved shape agreement in NNPDF3. Overall fit quality for LHCb experiments: χ /N =.4 (.9) at NNLO (NLO). Note NNLO crucial 8 Juan Rojo LHCb EW meeting, 3/0/07

Forward W,Z production at LHCb.5 4 NNLO, Q = NNPDF3., no LHCb data GeV ) [ref] ) / u ( x, Q u ( x, Q..05 0.95 0.9 NNPDF3.

9 Forward W,Z production at LHCb.5 4 NNLO, Q = NNPDF3., no LHCb data GeV ) [ref] ) / u ( x, Q u ( x, Q NNPDF3., with LHCb data The reduction of PDF uncertainties from the LHCb data is more marked for the large-x quarks Note shift on central values, in addition to reducing PDF errors For the down quark, PDF errors decrease by almost a factor for x=0. x ) [ref] ) / d ( x, Q d ( x, Q NNLO, Q = 0 GeV NNPDF3., no LHCb data NNPDF3., with LHCb data 9 0 Juan Rojo LHCb EW meeting, 3/0/07 x

strange than up and down sea quarks in the proton, which is very difficult to understand from non-perturbative QCD

10 The strangeness content of the proton xfitter analysis of the ATLAS W,Z 0 inclusive data prefers a symmetric strange sea with small uncertainty, at odds with all other PDF fits Actually the ATLAS data suggest that there are more strange than up and down sea quarks in the proton, which is very difficult to understand from non-perturbative QCD arguments Can one accommodate the ATLAS W,Z 0 data in the global fit? What happens to strangeness? Juan Rojo LHCb EW meeting, 3/0/07

11 The strangeness content of the proton Confirmed the strange symmetric fit preferred by the ATLAS W,Z 0 measurements, though we find PDF uncertainties larger by a factor The global fit accommodates both the neutrino data and the ATLAS W,Z 0 ( χ nutev=., χ AWZ=.8 ) finding a compromise value for R S = Mild tension in the global fit (.5-sigma level at most) when simultaneously included neutrino data, CMS W+charm and ATLAS W,Z 0+0 Juan Rojo LHCb EW meeting, 3/0/07

12 The strangeness content of the proton NNLO, Q=.65 GeV ) ( x, Q R S.6 NNPDF3.0 NNPDF3. global.4 NNPDF3. collider x Collider-only and global fits in agreement within PDF uncertainties In NNPDF3. strangeness is less suppressed than in NNPDF3.0 (mostly due to the new data) but still in agreement within PDF uncertainties The collider-only fit is becoming competitive with the global fit Juan Rojo LHCb EW meeting, 3/0/07

13 Jets at NNLO If the jet pt is used as central scale, NNLO/NLO K-factors only a few percent NNLO/NLO shift within NLO scale uncertainties J. Currie, Krakow 0/7 This trend holds for all rapidity regions NNLO results available only for then ATLAS 7 TeV 0 measurement In NNPDF3., use NLO matrix elements for jets, computed with pt as central scale, and add the NLO scale uncertainties as additional theory uncertainty 3 Juan Rojo LHCb EW meeting, 3/0/07

14 Impact of Z pt data.5 4 NNLO, Q = NNPDF3. no Z pt GeV.5 4 NNLO, Q = NNPDF3. no Z pt GeV ) [ref] ) / g ( x, Q g ( x, Q NNPDF3. ) [ref] ) / d ( x, Q d ( x, Q NNPDF x 0.9 x For the first time in a global fit, the transverse momentum of the Z boson included NNLO calculations for K-factors from Boughezal and Petriello, very CPU time intensive Impact on all PDFs: harder gluon at medium-x (relevant for ggf Higgs) and softer quarks in the same region. This is the region where Z pt data is expected to have direct sensitivity. New important addition to the toolbox of global PDF fits 4 Juan Rojo LHCb EW meeting, 3/0/07

15 Impact of Z pt data ATLAS 8 TeV (M,pT) CMS 8 TeV (y,pt) NNPDF3. NNPDF3. Good fit quality to 8 TeV ATLAS and CMS, though very sensitive to stat fluctuations Included % of residual stat uncertainty from K-factor calculation, else χ (NNLO) worse by factor 4. Tiny changes in shape of TH prediction worsen significantly fit quality since exp uncorr errors v small Despite fitting 8 TeV data, rather worse description of 7 TeV data (tension between 7 and 8 TeV?) 5 ATLAS 8 TeV (y,pt) ATLAS 8 TeV (M,pT) CMS 8 TeV (y,pt) χ χ Juan Rojo ATLAS PDF Fit Forum, /0/07

16 Sensitivity to correlation model In several of the new experiments in NNPDF3., uncorrelated uncertainties are very small, at the few permille level. This implies that is required to get the shape of the theory prediction correct to the same accuracy, which can be very challenging for CPU-intensive NNLO calculations We tackle this by including the MC stat integration error from the theory prediction as an additional uncorrelated systematic error in the χ This also implies that even very small variations of the correlation model (which ultimately determines what is correlated and what uncorrelated) can lead to very large variations of the χ for same input theory To avoid this, measurements should provide an estimate of the uncertainty associated with correlations 6 Juan Rojo LHCb EW meeting, 3/0/07

17 Impact on the gluon In NNPDF3. we have three groups of processes that provide direct information on the gluon: inclusive jets, top pair differential, and the Z transverse momentum 7 Are the constraints from each of these groups consistent among them? Yes ) [ref] ) / g ( x, Q g ( x, Q Global no Z pt data No top data No jet data 4 NNLO, Q = x GeV Juan Rojo LHCb EW meeting, 3/0/07

18 Impact on the gluon The best precision in the large-x gluon is achieved by combining jets with top-pair and Z pt data In terms of constraining power at large-x, we find the hierarchy: jets > ttbar differential > Z pt ) [ref] ) / g ( x, Q g ( x, Q Global no Z pt data No top data No jet data 4 NNLO, Q = GeV x Juan Rojo LHCb EW meeting, 3/0/07

19 Charm content of proton revisited The new LHC experiments provide additional constraints on non-perturbative charm Including the EMC charm data, we find evidence for non-perturbative charm at the.5 sigma level LHCb has a unique potential to further study non-perturbative charm in Z+D and open D meson production 9 Juan Rojo LHCb EW meeting, 3/0/07

20 Charm content of proton revisited Interestingly, the 7 and 8 TeV inclusive W,Z measurements from LHC also provide important information on the large-x charm content of the proton Models where non-perturbative charm can carry much more than % of the total proton s momentum are strongly disfavoured by the LHCb data ) ( x, Q NNLO, Q = GeV NNPDF3., no LHCb data NNPDF3., with LHCb data + x c x 0 Juan Rojo LHCb EW meeting, 3/0/07

21 Fit quality: χ NNLO FittedCharm NNLO PertCharm NLO FittedCharm NLO PertCharm HERA ATLAS CMS LHCb For collider data, NNLO theory leads to a markedly better fit quality that than NLO (since the new data included has small experimental uncertainties, and NNLO corrections mandatory) The global PDF analysis where the charm PDF is fitted leads to a slightly superior fit quality than assuming a perturbatively generated charm PDF In general good description of all the new collider measurements included in NNPDF3. Juan Rojo LHCb EW meeting, 3/0/07

22 Fitted charm vs perturbative charm.5 4 NNPDF3. NNLO, Q = GeV Fitted charm.5 4 NNPDF3. NNLO, Q = GeV Fitted charm ) [ref] ) / g ( x, Q g ( x, Q Perturbative charm ) [ref] ) / u ( x, Q u ( x, Q Perturbative charm 0.9 x 0.9 x.5 4 NNPDF3. NNLO, Q = GeV Fitted charm. Fitted charm 4 NNPDF3. NNLO, Q = GeV ) [ref] ) / d ( x, Q d ( x, Q Perturbative charm ) [ref] ( x, Q + ) / s ( x, Q Perturbative charm s x Juan Rojo LHCb EW meeting, 3/0/ x

23 Comparison with NNPDF3.0 ) [ref] ) / g ( x, Q g ( x, Q NNPDF3.0 NNPDF3. 4 NNLO, Q = GeV ) [ref] ) / u ( x, Q u ( x, Q NNPDF3.0 NNPDF3. 4 NNLO, Q = GeV NNPDF3.0 x 4 NNLO, Q = GeV 0.9. NNPDF3.0 x 4 NNLO, Q = GeV 3 ) [ref] ) / d ( x, Q d ( x, Q NNPDF3. x ) [ref] ( x, Q + ) / s ( x, Q + s NNPDF3. Juan Rojo LHCb EW meeting, 3/0/07 x

24 Charm production and the small-x gluon Gauld, Rojo, Rottoli, Talbert, JHEP 5 Gauld, Rojo, Rottoli, Sarkar, Talbert, JHEP 5 Gauld, Rojo, PRL 7 Juan Rojo LHCb EW meeting, 3/0/07

25 One glue to bind them all Gluinos, KK gravitons, boosted top-quarks. Higgs production in gluon fusion charm,bottom soft QCD, MC tuning, High-energy astroparticles Exploit PDF-sensitive LHC measurements to constrain the gluon at small-x 5 Juan Rojo Nikhef Jamboree, 3//06

26 The prompt flux at neutrino telescopes Observation of Ultra-High Energy (UHE) neutrino events heralds start of Neutrino Astronomy New window to the Universe, but interpretation of UHE data requires control over backgrounds IceCube/KM3NET/ How well do we understand this prompt flux? Do we really control charm production in such extreme kinematics? Juan Rojo LHCb EW meeting, 3/0/07 6

E lab 4 TeV Overlap kinematics between charm production in UHE

27 The low-x gluon from charm production c D + ν+x c Lab frame E lab = (m p E CR ) / Sensitivity to small-x gluon E CR = 0 PeV E lab 4 TeV Overlap kinematics between charm production in UHE cosmic rays and at the LHC Juan Rojo LHCb EW meeting, 3/0/07 7

The low-x gluon from charm production Strategy: use LHC data to provide state-of-the-art predictions for backgrounds at neutrino telescopes Include 7 TeV LHCb forward charm production data in the

28 The low-x gluon from charm production Strategy: use LHC data to provide state-of-the-art predictions for backgrounds at neutrino telescopes Include 7 TeV LHCb forward charm production data in the global fit Validate perturbative QCD calculations on collider data, and constrain the small-x gluon Compute optimised predictions for prompt neutrino fluxes at high energies ) = 4 GeV g ( x, Q NNPDF3.0 NLO α s =0.8 0 no LHCb D,D 0 +- data with LHCb D,D data (wgt) 0 +- with LHCb D,D data (unw) x We predict that detection of the prompt neutrino flux should be within reach Juan Rojo LHCb EW meeting, 3/0/07 8

29 LHCb charm production from 5 to 3 TeV Updated analysis based on normalized cross-sections at 5, 7 and 3 TeV and cross-section CoM energy ratios (avoiding double counting) Good description of all datasets, compatible pull on the small-x gluon except the R3/7 ratio The N 5 +N 7 +N 3 combination leads to a reduction of the small-x gluon PDF errors by an order of magnitude The most precise D0 data at 5 and 3 TeV cannot be described by NLO QCD and are excluded from the fit: NNLO calculation needed? Juan Rojo LHCb EW meeting, 3/0/07 9

30 UHE neutrino-nucleus cross-sections High-precision QCD predictions of neutrino-nucleus cross-section up to 6 PeV (low-x sea quarks driven by gluon through DGLAP evolution) Few-percent QCD uncertainties in the UHE cross-sections up to the highest energies: unique opportunity for BSM searches and precision astrophysical studies ν q(x -7,Q M W ) W/Z Precision studies of extreme QCD with IceCube/KM3NET: the ultimate DIS experiments Juan Rojo LHCb EW meeting, 3/0/07 30

31 Summary and outlook LHCb measurements provide a unique handle on the structure of the proton, from quark flavour separation at large x and the gluon at small-x to non-perturbative charm The 7 and 8 TeV inclusive W and Z production measurements reduce the uncertainties of the large-x quarks, by almost a factor in some cases Charm production measurements at LHCb allow a precision determination of the small-x gluon, with direct implications for ultra-high energy astrophysics NNPDF3. to be released in LHAPDF within the next few weeks 3 Juan Rojo LHCb EW meeting, 3/0/07

32 Extra Material Juan Rojo LHCb EW meeting, 3/0/07

33 Jets at NNLO If the jet pt is used as central scale, NNLO/NLO K-factors only a few percent NNLO/NLO shift within NLO scale uncertainties This trend holds for all rapidity regions J. Currie, Krakow 0/7 33 Juan Rojo LHCb EW meeting, 3/0/07

34 Inclusive jets 7 TeV 0 In NNPDF3., included only central rapidity bin (most constraining one for PDF purposes) with good fit quality: χ (NNLO)=.06 and χ (NNLO)=. Excellent description of the separate rapidity bins, but very high χ when including the complete correlations between rapidity bins Note that we include NLO scale errors, and we know that (NNLO-NLO) is well contained within these, so theoretical calculations (either matrix elements or PDFs) highly unlikely to be the source of the high χ problem ) [ref] ) / g ( x, Q g ( x, Q NNLO, Q = Global No jet data GeV Impact of jet data in NNPDF3. ) [ref] ) / d ( x, Q d ( x, Q NNLO, Q = Global No jet data GeV x x 34 Juan Rojo LHCb EW meeting, 3/0/07

35 The strangeness content of the proton NNPDF3. Significant improvement in description of the experimental data in NNPDF3. as compared to Juan Rojo LHCb EW meeting, 3/0/07

The gluon PDF: from LHC heavy quark production to neutrino astrophysics

! The gluon PDF: from LHC heavy quark production to neutrino astrophysics Juan Rojo! VU Amsterdam & Theory group, Nikhef!! Nikhef Jamboree 2016! Groningen, 13/12/2016 Juan Rojo 1 Nikhef Jamboree, 13/12/2016