Search For New Physics
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Transcript Search For New Physics
Search For New Physics
Chary
U of S
The Beyond-the-SM Physics at the LHC
Completely New Symmetries
Why do we have three generations of quarks and
leptons?
Is there any symmetry connecting quarks and leptons?
Are there more generations?
Do quarks and leptons have structure?
Is Higgs a composite particle?
Does t-quark play a special role?
What explains the shape of Higgs potential?
How to reconcile gravity with other fundamental forces?
What is the ultimate symmetry of nature?
How to explain baryogenesis?
How did the universe evolve right after the Big Bang? Is it
the unique solution?
Too Many questions
Too few Answers
Two Avenues
• Search for evidence of symmetry
breaking
• Search for new structures
Precision frontier
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New structures
• Particles not anticipated by the SM
more Higgs, more Zs, exotica in
particle interactions
Randall-Sundrum (RS) Model
PRL83 (1999) 3370
• There is one extra spatial dimension, and the 5D geometry is “warped” by the presence
of one or more branes.
• The fifth dimension consists of two periodically identified mirror copies of a curved 5D
space extending from x5=0 (Plank brane) to x5=L (SM brane).
M3
M Pl
(1 e 2 kL )
• The 4 dimensional Plank scale
2k
M: 5D Plank scale, the Anti-deSitter radius of curvature =1/k
•The graviton field is expanded into
h ( x, x5 ) h ( x)
(n)
n 0
( n ) ( x5 )
h(x) : KK modes of the graviton
Rc
• The KK modes of the gravition have the spectrum
M n xn kekRC xn m0
xn: n-th modified Bessel function
The interaction Lagrangian in the 4D effective theory
C0 k / M Pl
1 (0) 1 ( n )
L
T h
T h
M Pl
n 1
• There exist a new Higgs-like particle “radion” which is a modulus field describing relative
motion of the two brans.
L SM
1
T (SM )
e krc M Pl TeV
1. Graviton Resonance Production
Assuming the first excitation G(1) decays only into SM states.
qq , gg G
(1)
l l
: Dilepton resonance
qq , gg G (1) qq , gg : Dijet resonance
: Diphoton resonance
qq , gg G
(1)
qq , gg G
(1)
W W , W l , qq'
(a)
qq , gg G
(1)
ZZ , Z l l , , qq
(b)
(a): dilepton + missing ET, single lepton + two jets, four jets
(b): four leptons, dilepton + two jets, four jets
Search for the Di-electrons in CMS
Heavy resonances > 0.7 TeV decaying into 2 electrons
predicted by:
• Extra dimension theories
• TeV-1 Kaluza-Klein excitation of gauge boson (KKZ),
M+ and M- model, mass M > 4 TeV (present limit)
• Randall-Sundrum 2 parameters:
coupling constant c, mass M , M > .5 for c = 0.1
• Z’ in extensions of the Standard Model, M > 0.6 - 0.9
• Sequential Standard Model (SSM)
• Z, Z, Z in E6 and SO(10) groups
• “left-right” and “alternative ..” models (ZLRM , ZALRM)
From Fermilab
• We have performed a search for new
physics in 1/fb of data from CDF's Run
II. In our tighter selection, We expect
7.9±1.0 events from Standard Model
background sources and observe
thirteen. In our inclusive selection, we
expect 33.7±3.5 events and we
observe 44. We observe an excess of
events in the high momentum leading
lepton distribution.
Symmetry breaking
observbles
• Asymmetries in decays,
• Decay correlation asymmetries in
angular and polarization distributions
• Search for non-zero odd EM moments
• Flavor oscillations
SuSy Higgs
• Physical States: h,H, A, H±
• Parameters: mA and tan = v2/v1
F= -2 mixing in Bs decay
• BR (Bsbar SM= (3.46± 1.5)x 10-9
• BR (Bsbar CDF < 8 x 10-8 (2006)
Rick Van Kooten, Indiana (D0 collaboration)
F= -2 mixing
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• Don’t go away with the impression that
Only Mega physics with million people
can contribute
Ex: Neutron Decay
Left-right symmetric models
WL cos W1 sin W2
WR cos W2 sin W1
Right handed V+A couplings in the weak interaction derived from neutron
decay observables
Schumann hep-ph/ 07053769
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