Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens...
Transcript of Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens...
![Page 1: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/1.jpg)
Theoretical results for top quark processes
Nikolaos Kidonakis(Kennesaw State University)
• tt total and differential cross sections
• Single top: t and s channels
• tW− and tH− production
• ttW and ttZ production
• FCNC processes
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 1
![Page 2: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/2.jpg)
Top-pair production
q
q
t
t
• qq → ttdominant at Tevatron
g
g
t
t
g
g
t
t
g
g
t
t• gg → ttdominant at LHC
QCD corrections significant for top pair productionKnown fully at NLO (differential) and NNLO (numerical total only)Soft-gluon corrections are dominant near thresholdNNLL resummation of soft-gluon corrections
NNLO expansions (differential and total)
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 2
![Page 3: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/3.jpg)
tt cross section at the LHC
165 170 175 180m
t (GeV)
100
120
140
160
180
200
220
σ (p
b)
NNLO approx+- scale and pdfCMSATLAS
pp -> tt at LHC S1/2
= 7 TeV
165 170 175 180m
t (GeV)
160
180
200
220
240
260
280
300
320
340
σ (p
b)
NNLO approx+- scale and pdfCMS
pp -> tt at LHC S1/2
= 8 TeV
Very good agreement at both 7 and 8 TeV LHC energies
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 3
![Page 4: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/4.jpg)
Differences between various resummation/NNLO approx approaches
Total vs differential cross sectionmoment-space pQCD vs SCET
Name Observable Soft limitsingle-particle-inclusive (1PI) dσ/dpT dy s4 = s + t1 + u1 → 0
pair-invariant-mass (PIM) dσ/dMttdθ (1 − z) = 1 − M2tt/s → 0
production threshold σ β =√
1 − 4m2t /s → 0
The more general approach is double-differential→ pT and rapidity distributions
total-only approaches are limit/special case (absolute vs partonic threshold)
For differential calculations, further differences arise from how the relations + t1 + u1 = 0 is used in the plus-distribution coefficients, how subleadingterms are treated, damping factors, etc.
see N. Kidonakis and B.D. Pecjak, Eur. Phys. J C 72, 2084 (2012)
for details and review
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 4
![Page 5: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/5.jpg)
150 200 250 300 350
σ (pb)
NLO
NNLO Czakon et al
Kidonakis
Aliev et al
Ahrens et al
Beneke et al
Cacciari et al
Top quark theoretical calculationsLHC 7 and 8 TeV m
t=173 GeV σ (pp->tt) +- scale MSTW2008 pdf
Comparison of various NNLO approx approachesall with the same choice of parameters
Kidonakis, PRD 82, 114030 (2010) differential-pQCDAliev et al, CPC 182, 1034 (2011) total-pQCDAhrens et al, PLB 703, 135 (2011) differential-SCETBeneke et al, NPB 855, 695 (2012) total-SCETCacciari et al, PLB 710, 612 (2012) total-pQCD
6 6.5 7 7.5 8 8.5 9
σ (pb)
NLO
NNLO
Kidonakis
Aliev et al
Ahrens et al
Beneke et al
Cacciari et al
Top quark theoretical calculationsTevatron 1.96 TeV m
t=173 GeV σ (pp->tt) +- scale MSTW2008 pdf
750 800 850 900 950 1000 1050 1100 1150
σ (pb)
NLO
NNLO
Kidonakis
Aliev et al
Ahrens et al
Beneke et al
Top quark theoretical calculationsLHC 14 TeV m
t=173 GeV σ (pp->tt) +- scale MSTW2008 pdf
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 5
![Page 6: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/6.jpg)
Varying degree of success of the various approaches
The Kidonakis PRD 82 result is very close to the exact NNLO:both the central values and the scale uncertainty are nearly the sametrue for all collider energies and top quark masses
This was expected from comparison to NLO, and comparison of 1PIresults at NNLO in 2003
(PRD 68, N. Kidonakis & R. Vogt; see also discussion in PRD78 and PRD82)
less than 1% difference between NLO approximate and exact cross sectionsat both NLO and NNLO
In near future add approximate NNNLO
(see N. Kidonakis PRD 73,034001 (2006) for early NNNLO results)
This is the only calculation for partonic threshold at the double differentialcross section level using the standard moment-space resummation in pQCD
stability of the theoretical NNLO approx result over the past decade
the reliability of the NNLO approximate result and near-identical value toexact NNLO is very important for several reasons
• provides confidence of application to other processes (single-top, W, etc)• used as background for many analyses (Higgs, etc)
• means that we have near-exact NNLO pT and rapidity distributions
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 6
![Page 7: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/7.jpg)
Soft-gluon approximation for distributions
The approximation works very well both for total cross sections and differential
distributions
0 20 40 60 80 100 120 140 160 180 200p
T (GeV)
0.01
0.1
1
dσ/d
p T (
pb/G
eV)
NLO approxNLO exact
Top quark pT distribution at LHC S
1/2=8 TeV µ=m
t=173 GeV
excellent approximation:1% difference between NLO approximate and exact differential distributions
For best prediction add NNLO approx corrections to exact NLO cross section
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 7
![Page 8: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/8.jpg)
Top quark pT distribution
0 50 100 150 200 250 300 350 400p
T (GeV)
0
20
40
60
80
dσ/d
p T (
fb/G
eV)
D0
NNLO approx mt/2<µ<2m
t
Top quark pT at Tevatron S
1/2=1.96 TeV m=170 GeV
200 250 300 350 4000.1
1
10
0 50 100 150 200 250 300 350 400p
T (GeV)
0
0.002
0.004
0.006
0.008
1/σ
dσ/
dpT (
GeV
-1)
NNLO approx +- scale+ CMS l+jets
Normalized top pT distribution at LHC S
1/2=7 TeV m
t=173 GeV
Excellent agreement of NNLO approx results with Tevatron and LHC data
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 8
![Page 9: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/9.jpg)
Top quark pT distribution at the LHC
0 200 400 600 800 1000 1200 1400p
T (GeV)
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
dσ/d
p T (
pb/G
eV)
8 TeV µ=mt
8 TeV µ=mT
7 TeV µ=mt
7 TeV µ=mT
Top quark pT distribution at LHC NNLO approx m
t=173 GeV
0 50 100 150 200 250 300 350p
T (GeV)
0
0.5
1
1.5
2
dσ/d
p T (
pb/G
eV)
NLO 8 TeVNLO 7 TeVNNLOappr 8 TeVNNLOappr 7 TeV
Top quark pT distribution at LHC µ=m
t=173 GeV
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 9
![Page 10: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/10.jpg)
Top quark rapidity distribution at LHC
-3 -2 -1 0 1 2 3Y
0
20
40
60
80
dσ/d
Y (
pb)
NNLOappr 8 TeVNLO 8 TeVNNLOappr 7 TeVNLO 7 TeV
Top quark rapidity distribution at LHC µ=mt=173 GeV
-3 -2 -1 0 1 2 3Y
0
0.1
0.2
0.3
0.4
1/σ
dσ/
dY
NNLO approx +- scaleCMS dileptons
Normalized top Y distribution at LHC S1/2
=7 TeV mt=173 GeV
excellent agreement with data
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 10
![Page 11: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/11.jpg)
Single-top partonic processes at LO
b
q (q)
W
t
q′ (q′)• t channel: qb → q′t and qb → q′tdominant at Tevatron and LHC
q′
q
W
t
b• s channel: qq′ → btsmall at Tevatron and LHC
g
b
W
t
g
b
t
W
• associated tW production: bg → tW−
very small at Tevatron, significant at LHC
Related process: bg → tH−
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 11
![Page 12: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/12.jpg)
Single top t-channel cross sections at LHC
165 170 175 180m
t (GeV)
0
20
40
60
80
100
σ (p
b)
8 TeV top7 TeV top8 TeV antitop7 TeV antitop
t-channel LHC NNLO approx (NNLL) µ =mt
1 2 3 4 5 6 7 8 9 10 11 12 13 14S
1/2 (TeV)
1
10
100
σ (p
b)
NNLO approx+ - scale and pdf D0CDFCMSATLAS
t-channel total cross section mt=172.5 GeV
LHC t t Total (pb)
7 TeV 43.0+1.6−0.2
± 0.8 22.9 ± 0.5+0.7−0.9
65.9+2.1−0.7
+1.5−1.7
8 TeV 56.4+2.1−0.3
± 1.1 30.7 ± 0.7+0.9−1.1
87.2+2.8−1.0
+2.0−2.2
14 TeV 154+4
−1± 3 94+2
−1
+2
−3248+6
−2
+5
−6
mt = 173 GeV
± scale ± pdf errors with MSTW2008 NNLO pdf 90% CL
ratio σ(t)/σ(t) = 1.88+0.11
−0.09at 7 TeV - compares well with ATLAS result 1.81+0.23
−0.22
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 12
![Page 13: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/13.jpg)
t-channel top and antitop pT distributions at LHC
20 40 60 80 100 120 140p
T (GeV)
0
0.2
0.4
0.6
0.8
dσ/d
p T (
pb/G
eV)
8 TeV7 TeV
t-channel top quark pT distribution at LHC µ=m
t=173 GeV
NNLO approx (NNLL)
20 40 60 80 100 120 140p
T (GeV)
0
0.2
0.4
0.6
0.8
dσ/d
p T (
pb/G
eV)
8 TeV7 TeV
t-channel antitop quark pT distribution at LHC µ=m
t=173 GeV
NNLO approx (NNLL)
100 200 300 400 500 600 700 800 900 1000p
T (GeV)
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
dσ/d
p T (
pb/G
eV)
14 TeV 8 TeV 7 TeV
t-channel top quark pT distribution at LHC µ=m
t=173 GeV
NNLO approx (NNLL)
100 200 300 400 500 600 700 800 900 1000p
T (GeV)
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
dσ/d
p T (
pb/G
eV)
14 TeV 8 TeV 7 TeV
t-channel antitop quark pT distribution at LHC µ=m
t=173 GeV
NNLO approx (NNLL)
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 13
![Page 14: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/14.jpg)
Single top s-channel cross sections at LHC
165 170 175 180m
t (GeV)
0
2
4
6
8
σ (p
b)
8 TeV top7 TeV top8 TeV antitop7 TeV antitop
s-channel LHC NNLO approx (NNLL) µ =mt
2 3 4 5 6 7 8 9 10 11 12 13 14S
1/2 (TeV)
1
10
σ (p
b)
NNLO approx +-scale&pdfATLAS 95% CL limit
s-channel total cross section mt=172.5 GeV
LHC t t Total (pb)
7 TeV 3.14 ± 0.06+0.12−0.10
1.42 ± 0.01+0.06−0.07
4.56 ± 0.07+0.18−0.17
8 TeV 3.79 ± 0.07 ± 0.13 1.76 ± 0.01 ± 0.08 5.55 ± 0.08 ± 0.21
14 TeV 7.87 ± 0.14+0.31
−0.283.99 ± 0.05+0.14
−0.2111.86 ± 0.19+0.45
−0.49
mt = 173 GeV
NNLO approx: enhancement over NLO (same pdf) is ∼ 10%
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 14
![Page 15: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/15.jpg)
Associated tW− production at the LHC
2 3 4 5 6 7 8 9 10 11 12 13 14S
1/2 (TeV)
1
10
100
σ (p
b)
NNLO approx+- scale&pdfCMSATLAS
tW- + tW
+ cross section m
t=172.5 GeV
0 50 100 150 200p
T (GeV)
0
0.02
0.04
0.06
0.08
0.1
dσ/d
p T (
pb/G
eV)
8 TeV 7 TeV
tW-channel top quark pT distribution at LHC µ=m
t=173 GeV
NNLO approx (NNLL)
LHC tW− (pb)
7 TeV 7.8 ± 0.2+0.5−0.6
8 TeV 11.1 ± 0.3 ± 0.7
14 TeV 41.8 ± 1.0+1.5−2.4
mt = 173 GeV
NNLO approx corrections increase NLO cross section by ∼ 8%
Cross section for tW+ production is identical
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 15
![Page 16: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/16.jpg)
Associated production of a top quark with a charged Higgs
200 400 600 800 1000m
H- (GeV)
0.001
0.01
0.1
1σ
(pb)
14 TeV 8 TeV 7 TeV
bg-> tH- at LHC NNLO approx (NNLL) tanβ=30 µ=m
H-
NNLO approx corrections increase NLO cross section by ∼ 15 to ∼ 20%
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 16
![Page 17: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/17.jpg)
Associated production of a tt pair with bosons
Campbell and Ellis, JHEP 1207 (2012) 052
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 17
![Page 18: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/18.jpg)
ttW production
d
u
t
W−
t
u
d
W+
t
t
6 6.5 7 7.5 8 8.5 9
S1/2
(TeV)
0
50
100
150
σ (f
b)
t t W+
t t W-
pp -> t t W+ and pp -> t t W
-
mt=173.5 GeV µ=m
t+m
W/2 σ (pp->ttW) +- scale CTEQ6.6M pdf
Garzelli, Kardos, Papadopoulos, Trocsanyi, JHEP 1211 (2012) 056
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 18
![Page 19: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/19.jpg)
ttZ production
g
g
t
t
Z
g
g t
t
Z
q
q t
t
Z
q
q
t
t
Z
6 6.5 7 7.5 8 8.5 9
S1/2
(TeV)
100
150
200
250
σ (f
b)
t t Z
pp -> t t Z m
t=173.5 GeV µ=m
t+m
Z/2 σ (pp->ttZ) +- scale CTEQ6.6M pdf
Garzelli, Kardos, Papadopoulos, Trocsanyi, JHEP 1211 (2012) 056
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 19
![Page 20: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/20.jpg)
FCNC processes
Single-top production via flavor-changing neutral currentsAnomalous couplings in Lagrangian, e.g.
∆Leff
=1
ΛκtqV e t σµν q F
µν
V+ h.c.
gu → tZg
u
ut
Z
g t
t
u Z
gu → tγg
u
ut
γ
g t
t
u γ
eu → ete e
γ
u t
e e
Z
u t
decrease of scale dependence, significant corrections over LO
Future studies at LHC energies and for other couplings
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 20
![Page 21: Theoretical results for top quark processes · Aliev et al, CPC 182, 1034 (2011) total-pQCD Ahrens et al, PLB 703, 135 (2011) differential-SCET Beneke et al, NPB 855, 695 (2012)](https://reader034.fdocuments.in/reader034/viewer/2022042805/5f5facfc042d4b19ae7aeebc/html5/thumbnails/21.jpg)
Summary
• NNLL resummation / NNLO expansions
• tt production cross section
• top quark pT and rapidity distributions
• single top cross sections and pT distributions
• NNLO approx corrections are very significant
• excellent agreement with LHC and Tevatron data
• tH− associated production
• top-pair associated production with W+, W−, Z
• top quark FCNC processes
N. Kidonakis, Snowmass 2013, Brookhaven, April 2013 21