physics at vlhc - tao han

8/9/2019 Physics at VLHC - Tao Han

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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

5

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’

’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’

’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!

physics at vlhc - tao han

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