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Tao HanPittsburgh Particle physics, Astrophysics and Cosmology Center
Physics At VLHC
Exploring the Physics Frontier with Circular Colliders ACP Winter Conference, Jan. 27, 2015
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Photo credit: Hitoshi Murayama
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PHYSICS AT 100-200 TeV
Tao Han, Univ. of Wisconsin-Madison
(1999 VLHC Annual Meeting, June. 28)
I. Brief Introduction:
• Particle Physics and Colliders
II. Physics Expectations at the VLHC:
• Representative SM Physics
• Physics Beyond the SM
III. Physics at the High-Energy Frontier
• Be ond the Naive Ex ectation
PHYSICS AT THE VLHC
Tao Han, Univ. of Wisconsin-Madison
(July 17, Snowmass 2001)
VLHC: The True Energy Frontier
• Invitation to Innovative Ideas
for New Physics
Beyond the SM Physics• New Threshold and Extended Reach
Bread and Butter Physics
• SM Physics and Precisions
Theory Overview
in the light of future hadron colliders
Tao Han
Univ. of Wisconsin - Madison
VLHC workshop, Fermilab, Oct. 16, 2003
The Standard Model as It Is
The Need For Going Beyond SMThe Role of Future Hadron Colliders
(Bill Foster’s initiative)
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• M W , M Z ? (Gauge symmetry breaking)
• M H ∼ O(M Z )? (natural EW scale)
• Supersymmetry? (M Z − M pl hierarchy)
• mt, mf , mν ? (fermion masses and mixing)
• Techni-/top-color? (dynamical symm. brkng)
• extra dimensions/low-scale gravity?
(gravity+hierarchy)
• Superstring?
(quantum gravity/Theory of everything?)
• ... ...? (... ...)
Physics Issues in 1999 (TH’s list)
!
"
!
?
DM
?
?
?
?
?
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Chris Quigg, IAS-HKUST Jan. 19, 2015
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-
Snowmass QCD Working Group: 1310.5189
!t : 1% ! : 8%
Rich Physics @ VLHC
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VLHC leads energy frontier
Interesting scaling:
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SUSY @ VLHC
M.Mangano, T.Plehn et al.: 1407.5066
discovery
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SUSY DM @ VLHC
M. Low & L.T. Wang: 1404.0682
mass [TeV]
0 1 2 3 4 5 6 7
wino / higgsino
higgsino / wino
higgsino / bino
wino / bino
NLSP mass
LSP mass
Multi-Lepton Limits
S. Gori et al.: 1410.6287
[TeV]!"m
0 1 2 3 4 5 6
wino disappearing tracks
higgsino
)H~
/ B~
mixed (
)W~
/ B~
mixed (
gluino coan.
stop coan.
squark coan.
Collider Limits
100 TeV14 TeV
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-
Snowmass NP report, 1311.0299
New Particle Searches at VLHC
VLHC leads for broad searches at the energy frontier. Look forward to the many
inspiring talks this week!
pp virtual
ee virtual
pp real
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The EW gauge bosons & the top quark prettymuch “massless”: the EW symmetry is “restored”
At the new energy frontier VLHC: v/√ s∼
2.5×10−3
In the collision processes
•
Initial particles! partons • Final state particles! narrow jets, radiations
• New physics @ heavier scales! W ± /Z/H/top ! Studying W ± /Z/H/top at higher energies: - bread & butter (new) phenomena within SM
- first step toward understanding
O(10 TeV) scale physics
New behavior of “old physics”
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With mt
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With mt ~ v,
The top quark may hold the key to new physics:• Most sensitive to the “naturalness” issue.
• Vacuum stability
• … …
Top quark Initiated Processes
spin 0 : neutral scalar H 0 : i y√
2; pseudo scalar A0 : i
y√ 2γ 5;
charged scalar H
+
: i
y
√ 2(gLP L + gRP R);spin 1 : color − singlet vector/axial vector Z 00, W 0+ : igγ µ(gV − gAγ 5);
color − octet vector/axial vector gKK : igsγ µ(gV − gAγ 5) ta;spin 2 : tensor G :
−iκ
8
[γ µ( pt
− pt̄)
ν + γ ν ( pt
− pt̄)
µ
−2gµν (/pt
−/pt̄
−2mt)].
tt̄→ X Examples for new physics:
TH, J. Sayre, S. Westhoff: 1411.2588
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Top lumi tracking gg, reaching few% of bb! Relevant range:
Partonic luminosities σ pp→H +X (S ) =
i,j
1m2
H /S
dx1
1m2
H /(x1S )
dx2 f i(x1, µ) f j(x2, µ) σ̂ij→H (s)
≡i,j 1
m2H /S
dτ dLij
dτ σ̂ij(s),
dLij
dτ (τ , µ) =
1
τ
dx
x f i(x, µ)f j(τ /x,µ)
0.002
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5-flavor vs. 6-flavor: (ACOT: massive top with careful subtraction)
•
5-flavors usually underestimate the rate (better at low M) • 6-flavors usually overestimate the rate (better at high M)
(too much resummation)! proper treatment needed • Higher CM Energies better approximation
[TeV]0 H
m
1 2 3 4 5 6 7 8 9 10
[ f b ]
σ
-110
1
10
210
310
410
510
0 H → t t
0 H t t → gg
ACOT
100 TeV
[TeV]0 H
m
0.5 1 1.5 2 2.5 3 3.5 4
[ f b ]
σ
-310
-210
-110
1
10
210
310
0 H → t t
0 H t t → gg
ACOT
14 TeV
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“Effective”factorization scale
logµ2
eff
m2t
=
dxx f t(x,m
H 0) dz
z P tg(z ) log(
mH 0
m2
t
(1−z)2
z )f g(
τ
zx,m
H 0)
dxx f t(x,mH 0)
dzz P tg(z )f g(
τ
zx, mH 0)
100 TeV
14 TeV
2 4 6 8 100.0
0.1
0.2
0.3
0.4
0.5
0.6
m H 0
TeV
Μ e f f
m
H 0
100 TeV
t t H 0ggt t H
0
t t H 0
Μ Μeff
m ACOT Μ m H 0
2 4 6 8 100.1
1
10
100
1000
104
105
m H 0
TeV
Σ p p H 0
f b
[TeV]0 H
m
0 2 4 6 8 10
) 0
H
( m
! ) / µ
( !
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
/2 0 H
=m F
µ
0 H
=2m F
µ
eff µ =
F µ
0 H
=m R
µ “Natural” factorization scale
µ2≈ m
2
H
(Early discussions: Maltoni, Willenbrock)
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tb̄→ H +
* Dawson, Ismail, Low, 2014
Full NLO O("s) calculations, including NLO PDF’s.
t
b
H+
Another recent work *
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At colliding energies E >> M W ,EW gauge bosons are new “gluons”!
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Gauge-boson Initiated Processes
In the EW theory: P q→qV T = (g
2
V + g2
A) α2
2π
1 + (1− x)2
x ln
Q2
Λ2
P q→qV L = (g2
V + g2
A) α2
π
1− x
x•
V T radiation the same asg
, # : | M |2
~ pT2
:- “dead cone” at pT! 0 - log-enhancement at high pT & soft x
• V L radiation no collinear enhancement/suppression,
not the same as a scalar radiation.
“Effective W-Approximation”(VBF ! h is seen by ATLAS/CMS)S. Dawson, 1985;G. Kane et al., 1984;Chanowitz & Gailard, 1984
TH R R i B T di i
WW P i l i i i
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/ss=
0.02 0.04 0.06 0.08 0.1
-510
-410
-310
-210
-1101
10
210
310
410
510
610
710gg
qq’
q
W
-
TW+
TW
-
0W+
0W
PRELIMINARY - 100 TeV pp
Lumi(W +T W -T) similar size to lumi(tt); Lumi(W +T W
-T) ~ Lumi(W
± !), Electro=weak
Lumi(W +L W -L ) 100 times smaller: Goldstones
Lumi(100/14) increased by 1000 – 105 for 500 GeV - 4 TeV!
TH, R. Ruiz, B. Tweedie, in prep
ΦV V ′ (τ ) = 1
(δ V V ′ + 1)
1
τ
dξ
ξ
1
τ /ξ
dz1z1
1
τ /ξ/z1
dz2z2
q,q′
(7)
×f V /q(z2)f V ′/q′ (z1) f q/p(ξ )f q′/p
τ
ξ z1z2
+ f V /q(z2)f V ′ /q′ (z1) f q/p
τ
ξ z1z2
f q′/p(ξ )
[TeV]s0.5 1 1.5 2 2.5 3 3.5 4
1 4 T e V
/
1 0 0 T
e V
310
410
510
gg
qq’
q
W
-
TW+
TW
-
0W+
0W
WW Partonic luminosities
tt
W W S i
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• The existence of a light, weakly coupled Higgs boson unitarize the WW amplitude:
• Consistent perturbative theory up to $ (?)
500 1000 1500 2000 2500 3000105
106
107
s
`
@GeVD
Σ
@ f b D
W+W-->ZZ
Standard Model
no Higgs
−
ll i i i i i i
~ (g2 /16 " 2) s/v2
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W LW L Scattering:
~ s/v2
~ mH2 /v2
• New strong dynamics effects may still exist,
but “delayed” tov 2 / " 2 .
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I 0 1 2
J = 0 σ0 . φ−−,φ−,φ0,φ+,φ++
1 . ρ−, ρ0, ρ+ .
2 f 0 . t −−
,
t −
,
t 0,
t +,
t ++
. . . . . . . . . . . .
I = 0: resonant in W +W − and ZZ scattering
I = 1: resonant in W +Z and W −Z scattering
I = 2: resonant in W +W + and W −W − scattering
Different channels are sensitive to different physics:
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W LW L Scattering:
Equally important: WW ! HH, tt for H3 & top couplings.
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Multi Gauge-boson Production
From prompt production
Each W costs you a factor of ~ 1/100 (EW coupling)
M. Mangano’s talk
Multi Gauge boson Production
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At colliding energies E >> M v,
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In EW gauge boson splitting:
• V T the “new gluons”!
•
V L /H radiations the Goldstone Eq. Theo.
P V T →V T H = α
2
4π
1− x
x
P V T →V T V
0
T
= α2
2π[
1
x(1− x) + x(1− x)] ln
Q2
M 2W
P V T →V LV
0
L
= α2
4πx(1− x) ln
Q2
M 2W
Multi Gauge-boson Production
From splitting/showering:
J. Chen, TH, B. Tweedie, in prep
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Multi Gauge boson From showering:
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Multi Gauge-boson From showering:
Number of Z/W bosons
0! 1! 2! 3! 4! 5! 6!
P r o b a b i l i t y
-610
-510
-410
-310
-210
-110
1 > 1 TeVhard process
= 14 TeV, ps
> 10 TeVhard process
= 100 TeV, ps
Christiansen, Sjostrand: 1401.5238
f = 2.0
f = 1.1
f = 1.0
f = 0.0 pT J > 750GeV
m23 [GeV]
d σ / d m 2 3
p b / 2 G e V
1009080706050
0.36
0.34
0.32
0.3
0.28
0.26
0.24
0.22
0.2
f = 2.0
f = 1.1
f = 1.0
f = 0.0 pT J > 1000GeV
m23 [GeV]
d σ / d m 2 3
[ p b / 2 G e V
]
1009080706050
0.06
0.055
0.05
0.045
0.04
0.035
Kruass, Petrov, Schonher, Spannowsky:1403.4788
At higher energies, each W
costs you a factor of ~ 1/10 !
We are in the process ofdeveloping a more complete
EW showering code.J. Chen, TH, B. Tweedie
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Overall
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Overall
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* With the Higgs discovery, the SM is healthier than ever, valid to a scale up to $ ~ ?
But the Higgs sector fine-tuned % : * VLHC will take the lead for searches:
H±, A0; W ±’, Z’ … The top,W,Z,H may hold the key for
discovery!
g̃, t̃, b̃, χ±,0, ...
• Searching for new physics starts fromunderstanding old physics in the new regime:
- top,W,Z may behave as partons to produce new heavy states;
- top,W,Z,H may serve as new radiation sources; and may help reveal new heavy states.
- Thus, need precise understanding of the dynamics/kinematics
While new physics searches exciting,
SM Physics Remains rich at VLHC!