Alexandru Bratu Higgs Boson Strategies and Implications

7/31/2019 Alexandru Bratu Higgs Boson Strategies and Implications

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Strategies at LHC

( )τ τ →H + VBF

( )2135 /H

M GeV c =Medium Higgs boson mass

1

A full simulation of the signal and several background processes with low lum-

inosity eviroment of 10 is typically used. A rapidity gap enables the Higgs particle

to be viewed via an isolat

fb−

ed environment, to show the main differences between VBF

and QCD which sometimes tend to create central jets.

Figure above: An illustration of the η − Φ distribution of the objects in a signal

H →τ τ + event (the location of each object drawn with a circle), superimposed on top of

the statistical η distribution of the objects. The large separation between two forward jets

from the VBF production process leaves the central region with very low hadronic

activities.

For the Higgs decay at least one of the must go into a lepton

to allow a more flexible selection of events while at the same time another decays

hadronically.

particles τ

τ

−



The Higgs boson can be discovered by its decay products which form a reso-

nance peak in the data. In terms of background processes the neutral bosons decay

into 2 tau leptons which exhibit sim− ilar physical behaviour. However there is a

difference in tau polarization arising from the fact that the boson has spin 1and Higgs boson has 0.

Z

H

Z S S

− ==

Feynmann diagrams for Z background processes are shown below− :

2Feynman diagrams for the main QCD Z jets background processes +

⇓

2 2Feynman diagrams for the main EW tau jets background processes +

⇓

A tau jet or a narrow jet can be misidentified; however using these

events can be distinguished from each other with the signal process due to

a kinematical constraint on activity in the rapidi

−

ty gap. The invariant mass

of like objects does not form the resonance peak itself, therefore the

Higgs mass peak will stand out above it.

τ τ −

.



( )( )2

For the invariant masses of the taus involved, the predicted Higgs mass

is about 135 / from the background samples. *H

M

GeV c A1

( ) 1A luminosity of 30 is used with selection cuts distributed evenly.L fb−

For the fitting of the signal distribution we use Gaussian distributions

Breit Wigner formula.We also make use of the 2 order Lagrangian polynomial

technique which is allocated for the reso

nd

&

−

( )nance peak obtained from the Z and the

reducible backgrounds. *A1

2Invariant mass distribution of the system τ −

⇓

Application of the selection cuts gives Higgs mass distribution of about 10%. 1

1

The signal achieved from the Higgs boson had a 3.9 significance at 30

and 5 significance at about 60 .

fb

fb

σ

σ

−

−



4µ→ →* H ZZ ( )2 2170 / 600 /

H GeV c M GeV c ≤ ≤Medium Higgs boson mass

*

*

We discuss the 4 decay known as the golden plated channel

because of its reliability and small backgrounds , .The is a virtual

particle when 2 .The range of the HiggsZ H Z

H ZZ

tt Zbb & ZZ Z

Z m m m

µ→ →

≤ ≤

( )2

mass within this type of

decay is taken to be within 115 600 / .GeV c − A2 *

( )The experiment involved muon triggers that were based on a single muon

with 19 / pairs of with 7 / , which

in turn would allow a complete collection of arising HiggsT T

p GeV c & dimuons pair p GeV c µ µ+ −> − >

events. To avoid

systematic and statistical errors occurring,specific mouns were selected, more pre-

cisely the ones with transverse momentum 7 / .T

p GeV c >

( )( )

If they occurred within the central pseudorapidity region of 1.1 or with

total momentum 13 / , around the endcaps, i.e. 1.1 .p GeV c

η

η

<

> >

( ) 2

For the events we also had to make sure that all the combinations of the

dimuon masses satisfied 12 / to account for the less suppressed

hadronic background contributions.

m GeV c µ µ+ − >

For the cut optimization we had to make use of Monte Carlo simulations

that would maximize the counting experiment significance

−

S

( )significance at the onfidence evel of 95%

2 ln 2 , integrated luminosity

number of events

cL

cL

S S B

S S B S S B

B

⇒ + = + − ⇒ ⇒

c l

For the main backgrounds we had 3 important (partition of the vertices

of a graph into two sets)

cuts

:

These were :

( )1.

2. 2

3.

T

nd

T T

muon isolation used for QCD - background rejection

loosening of lower p cut such that more

p cut on the lowest p muon significant background contribution can be expected

( )4

250

M4 tubes have a UV transparent

M window for counting experiment window,which shifts the low

wavelength cut - off to nm

µ

≈



( )Significance vs. Higgs - boson mass : optimized cut values applied to the

first half of the statistics dashed line,empty circles and cuts as

smooth functions of 4 - muon invariant mass, applied to the

seco

cLS

( )nd half of the statistics solidline, filled circles

⇓

Diagram 1

( ) ( )( )

130

4

.

Expected excess significance with L fb for different

Higgs - boson masses forM dependent solid line and independent

cuts dashed line .No systematic errors included

µ

−=

−

⇓

LS

Diagram 2



( )

( )

The above diagram 1 shows the second half of the application of

the Monte Carlo events in cut optimization , mainly concentrating on the smooth

and continuous 4 functions.

Diagram

M µ

( )1

The second picture 2 represents the significance of the different

expected events of the various Higgs masses at luminosity of 30 .cL

Diagram S

fb−−

( )

1

2 2

The use of renormalization simplified the problem at hand so that we

could obtain a 5 level of significance early within the experiment at 10

with 140 150 / and 190 400 / .H

fb

M GeV c GeV c

σ −

− − A2 *

1

2 2

2

At the phase of 30 we would obtain the discovery range within the range

130 160 / and 180 500 / . Observations of the actual Higgs mass

approaching the range of 170 / or 600

fb

GeV c GeV c

GeV c Ge

−

− −

∼2 *

1 2 2

/ in the 4

decay requires 100 . It cannot be detected 170 / or 600 /

because the WW decay dominates the * one, afterwards becomes possible.

V c H ZZ

L fb GeV c GeV c

ZZ ZZ

µ−

→ →

≈ ∼



Implications if not found at the LHC

Upgrade

The main upgrade involves increasing the power by reducing statistical errorsin data and hence increase in the intensity of the colliding beams to achieve a much

higher luminosity. This boost

( )would extend the reach of electroweak physics and pro-

vide new modes in supersymmetric theories and massive particles. A8 *

( )SMStandard - Model

Experiments have verified all predictions with incredible precision

and all the particles but one have been found thanks to this theory, the missing particle

Higgs boson, which gives matter

SM

its mass. fails in the fact that the gravitational

force is not explained properly.

SM

In case the LHC fails to find the elusive particle there are also alternatives

theories to the Higgs mechanism for electroweak symmetry breaking.

superflu

Some of these are

Top quark condensate −

:

( )id phase formed

by fermionic particles at

low temperatures

physical model that mimics the

dynamics of the strong force,

breaking electroweak symmetry

Technicolor

− ⇒

A3 *

( )

A3 *

Quark Condensate

( )Should in theory no mass be given by the Higgs boson, an alternative theory

describing how particles acquire mass is the quark condensate.

Coming from the theoretical non supechiral −

A6 *

( )( )

rimposable mirror image

condensate in the field of quantum chromodynmics QCD we have that the QCD

vacuum is responsible for providing masses to hadrons, also with other condensates

like the gluon condensa

( ) ( )tes. In the process the QCD vacuum established breaks a

, with 6 flavours, i.e. . symmetry to form the quark condensate.

Therefore we establish that the condensate of the quark is an

SU N N u c t d s b

order

→

( )( )

( )( )

transformation of a thermodynamic system from one phase to another of the

(theorized phases of matter whose degrees of freedom include quarks and

gluons) .

parameter

quark matter

A4 *

A3 * A6 *





( ) 1.

.NP

Max

H

The maximum possible Higgs mass with a given scale

QCD scale

Dashed lines mark the values of M

Λ − ≤

⇑

Now in terms of a high top quark mass we can arrange a band for the

maximal Higgs boson with a completely new scale of measurements in terms of .Λ

The Higgs mass where the pertubative approach breaks down including two loop

effects. The upper band reflects the uncertainty in the calculation. The lower band

is a lower limit on the Higgs mass from stability arguments of the theory.

⇓



A maximum value for the Higgs Mass

Predictions of the Standard Model suggest that the Higgs mass has mainly

problems in terms of forecasting the breakdown of perturbation theory, i.e.thus causing predictions of the strongly int−

( ) ( )eracting high energy sector of VB

vector-boson interactions . Due to this circumstance we have that the Higgs

mechanism around the quantum expectation value of 246 GeV also breaks down.

From this arises

A9 *

the fact that the standard model may fail to exist but due to small

corrections the masses above 1 TeV could also be expected to be found by the LHC

no later than February 2009, a further delay, due to

( )( )

technical difficulties like

buckling part-connectors and low supplies of helium cooling units as discussed

earlier this year by executive Robert Aymar. A10 * March 2008 - PhysicsWorld

( )The amount of evidence provided would come around at a 90% chance of

finding the Higgs boson since it has been "discovered i.e. theoretically observed "

at all these specific ranges, from 140GeV 1 with few exceptions of

mass barely exceeding 1 .H

H

M TeV

M TeV

≤ ≤

≥

The search for Higgs continues...

( )

..."The Higgs gives everything in the universe its mass "

by

David Francis, a physicist on the ATLAS experiment A11 *



.http://www.hep.ph.ic.ac.uk/cms/physics/HIGGS/maiko_analysis.html

Search for the Standard Model Higgs boson in the jet

channel in the vector boson fusion prodcution

.http://th

H lepton τ τ → + → +

A1

A2

References*

( )

( )

-www.if.uj.edu.pl/acta/vol38/pdf/v38p0731.pdf

Search strategy for the Standard Model Higgs boson in the 4

decay channel using 4 dependent cuts.

.http://scienceworld.wolfram.com/physics

Eric Wei

H ZZ

M

µ

µ

→ →

−

*

A3

nssteins World of Physics

.Wikipedia,www.wikipedia.org

.http://www.hep.lu.se/atlas//thesis/egede/thesis-node20.html

A theoretical limit on the Higgs mass,Ulrik Egede,1 / 8 / 1998

.http://arxiv.org/PS_ca

A4

A5

A6 che/hep-th/pdf/0309/0309013v1.pdf

QCD Quark Condensate from SUSY and the Orientifold Large-N Expansion

by A.Armoni, M.Shifman, G.Veneziano

.http://arxiv.org/PS_cache/hep-ex/pdf/0011/0011086v2.pdf

The 1

A7

( )

15 GeV Higgs Odyssey,John Ellis,CERN TH/2000-307

.http://cerncourier.com/cws/article/cern/29308

LHC upgrade takes shape with CARE Coordinated Accelerator Research in Europe

and attention

.http://hepwww

−

A8

A9 .rl.ac.uk/accel/forum/2007/Campbell1.pdf

UK HEP Forum, LHC Start-up, April 12th 2007,Hard Interactions

.http://physicsworld.com/cws/article/news/31434

physicsworld.com CERN LHC news

.http://www.time

−

A10

A11 .com/time/health/article/0,8599,1729139,00.html

Journalistic article entitled "Higgs Boson : A Ghost in the Machine"

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Alexandru Bratu Higgs Boson Strategies and Implications