neutrino telescopes as qcd microscopesnnpdf.mi.infn.it/wp-content/uploads/2019/04/jrojo... ·...
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Juan RojoVU Amsterdam & Theory group, Nikhef
XXVII International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2019)
Juan Rojo WG1+WG7 Joint Session, DIS2019 1
Neutrino Telescopes as QCD Microscopes
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The small-x gluon from HERA data Small-x gluon unconstrained: information from HERA ends for x<10-4
Large uncertainties in global fits
Need processes covering x<10-4 region
2
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Forward charm productionLHC: charm production
from gluon-gluon scattering
LHCb: forward coverage,Charm probes down to x ≃ 10-6 !
nb: dependence on D meson fragmentation
3
Charm @ LHCb
Juan Rojo WG1+WG7 Joint Session, DIS2019
PROSA 14Gauld et al 15
Cacciari et al 15
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Forward charm productionInclude LHCb D meson production at 5, 7, 13 TeV
Fit normalised distributions & ratios between CoM energies to reduce MHOUs
gluon PDF uncertainties reduced by factor 10 at x ≃ 10-6
Excellent description of all LHCb datasets and ratios (after errata corrected)
4Gauld, JR 16
Juan Rojo WG1+WG7 Joint Session, DIS2019
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Forward charm production
x6−10 5−10 4−10 3−10
)2 =
4 G
eV2
x,Q
(xg
0
10
20
30
40
50
60CLσNNPDF3.0 1000 xg 1
0, flavs = D13+N7+N5N
+, flavs = D13+N7+N5N
s, flavs = D13+N7+N5N
Results stable wrt choice of fitted D meson species
5Juan Rojo WG1+WG7 Joint Session, DIS2019
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BFKL dynamics at small-x QCD calculations in the DGLAP factorisation framework successful in describing data from proton-proton and electron-proton collisions
Need to go beyond DGLAP: at small-x, logarithmically enhanced terms in 1/x become dominant and need to be resummed to all orders
BFKL (high-energy, small-x) resummation can be matched to DGLAP collinear framework and included into PDF fits
DGLAPEvolution in Q2
BFKLEvolution in x
ABF, CCSS, TW + others, 94-08
∂∂ ln Q2
fi(x, Q2) = ∫1
x
dzz
Pij ( xz
, αs(Q2)) fj(z, Q2)
∂∂ ln 1/x
f+(x, Q2) = ∫∞
0
dν2
ν2K ( Q2
ν2, αs(Q2)) f+(x, ν2)
6Juan Rojo WG1+WG7 Joint Session, DIS2019
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BFKL dynamics at small-x
3.4 3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 )
min- log ( x
1.04
1.06
1.08
1.1
1.12
1.14
dat
/ N
2 χ
NNPDF3.1sx, HERA inclusive structure functions
NNLO
NNLO+NLLx
NNPDF3.1sx, HERA inclusive structure functions
NNLO quality degrades as more small-x data included
Monitor the fit quality as one includes more data from the small-x region
Best description of small-x HERA data only possible with BFKL effects!
7
Ball et al 17, xFitter 18
Juan Rojo WG1+WG7 Joint Session, DIS2019
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small-x resummation: excellent perturbative convergence even for
x ≃ 10-6
Forward charm production revisited
8
LHCb D meson production included in NNPDF3.1sx (N)NLO+NLLx fits
Similar reduction of gluon PDF errors at small-x + increase in central value
BFKL effects included
Bertone, Gauld, JR 18
Juan Rojo WG1+WG7 Joint Session, DIS2019
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small-x resummation: excellent perturbative convergence even for
x ≃ 10-8
Forward charm production revisited
9
LHCb D meson production included in NNPDF3.1sx (N)NLO+NLLx fits
Similar reduction of gluon PDF errors at small-x + increase in central value
Juan Rojo WG1+WG7 Joint Session, DIS2019
8−10 7−10 6−10 5−10 4−10 3−10 x 1
10
210
310
x g
( x, Q
)
NNPDF3.1 NLO
NNPDF3.1 LO
NNPDF3.1sx+LHCb NLO+NLLx
NNPDF3.1sx+LHCb NNLO+NLLx
Q = 1.7 GeV
Suitable for MC tuning:available in Pythia8
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10
Neutrino telescopesUltra-high energy (UHE) neutrinos: novel window to the extreme Universe!
Juan Rojo WG1+WG7 Joint Session, DIS2019
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11
Neutrino telescopesUltra-high energy (UHE) neutrinos: novel window to the extreme Universe!
Juan Rojo WG1+WG7 Joint Session, DIS2019
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12
The birth of neutrino astronomy
First optical counterpart of UHE neutrino identified: a blazar!
Juan Rojo WG1+WG7 Joint Session, DIS2019
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13
Neutrino telescopes as QCD microscopes
Juan Rojo LHCb Implications Workshop, CERN, 17/10/2018
signal: cosmic neutrino - nucleus scattering background: prompt charm production
background: prompt charm
signal: cosmic neutrinos
Juan Rojo WG1+WG7 Joint Session, DIS2019
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14
air/water target
D-meson
background: prompt charm production
Sensitive to small-x quarks (and thus gluons via evolution) down to
x ≃ 10-8 and Q ≃ MW
Sensitive to small-x gluons down to x ≃ 10-6 and Q ≃ Mcharm in the
centre-of-mass frame
Neutrino telescopes as QCD microscopessignal: cosmic neutrino - nucleus scattering
Juan Rojo WG1+WG7 Joint Session, DIS2019
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15
background: prompt charm production
Sensitive to small-x quarks (and thus gluons via evolution) down to
x ≃ 10-8 and Q ≃ MW
Sensitive to small-x gluons down to x ≃ 10-6 and Q ≃ Mcharm in the
centre-of-mass frame
Neutrino telescopes as QCD microscopessignal: cosmic neutrino - nucleus scattering
Juan Rojo WG1+WG7 Joint Session, DIS2019
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16
UHE neutrino-nucleus cross-sectionBertone, Gauld, JR 18
State-of-the-art predictions for ultra-high energy neutrino interactions
BFKL small-x effects in PDFs and deep-inelastic structure functions
Constraints on small-x PDFs from LHCb charm production
Accounting for nuclear corrections and heavy-quark-initiated contributions
Juan Rojo WG1+WG7 Joint Session, DIS2019
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17
UHE neutrino-nucleus cross-sectionCharged Current
Differences both at intermediate (updated PDFs, improved treatment of heavy quarks) and high energies (LHCb constraints, BFKL effects)
Nuclear effects important: constrain them with LHCb charm production in p+Pb
IceCube and other neutrino telescopes are the ultimate QCD microscopes!
Juan Rojo WG1+WG7 Joint Session, DIS2019
Neutral Current
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UHE neutrino-nucleus cross-sectionComparison with previous results Comparison with IceCube data
Differences both at intermediate (updated PDFs, improved treatment of heavy quarks) and high energies (LHCb constraints, BFKL effects)
Nuclear effects important: constrain them with LHCb charm production in p+Pb
IceCube and other neutrino telescopes are the ultimate QCD microscopes!
Juan Rojo WG1+WG7 Joint Session, DIS2019
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19
Summary and outlook LHCb provides unique information on the structure of the proton
Charm production constraints small-x gluon beyond the HERA coverage
Neutrino astrophysics requires direct input from small-x QCD
Precision calculation of UHE neutrino-nucleon cross-section with LHCb charm data and BFKL small-x resummation
Ongoing implementation of BGR18 in GENIE will allow detailed phenomenological studies in neutrino (astro-)physics
Juan Rojo WG1+WG7 Joint Session, DIS2019