Dept of Physics “Particle” Pradipta Ghosh
th 12 March, 2019 March 12, 2019 1 / 30 1993
The Birth of God Particle Traveling Back In Time
March 12, 2019 2 / 30 The Birth of God Particle: Meet the Creators
Englert, Brout, Phys. Rev. Lett. 13, 321, 31 August 1964 Broken Symmetry and the Mass of Gauge Vector Mesons
Higgs, Phys. Rev. Lett. 13, 508, 19 October 1964 Broken Symmetries and the Masses of Gauge Bosons
Guralnik, Hagen, Kibble, Phys. Rev. Lett. 13, 585, 16 November 1964 Global Conservation Laws and Massless Particles
Contributors over years: Anderson, Brout, Englert, Guralnik, Hagen, Higgs, Kibble, and 't Hooft
Peter Higgs: It’s not Higgs boson but ABEGHHK'tH boson March 12, 2019 3 / 30 The Birth of God Particle: The Man Behind the Myth
1993
1988
Leon Max Lederman 1922 - 2018
“ the effort to reduce all the operations of nature to a small number of laws governing a small number of primordial objects”
March 12, 2019 4 / 30 1993
Asgard for God Particle ?
Asgard of God Particle The Standard Model (SM) of Particle Physics
Asgardians Elementary Particles
Basic Interactions and mediators
March 12, 2019 5 / 30 Theory: Glashow, 1961, Weinberg, 1967, Salam, 1968
1979 Sheldon Steven Abdus Glashow Weinberg Salam
Theory: Greenberg, 1964, Han, Nambu, 1964, Bardeen, Fritzsch, Gell-Mann, 1973 Creators of Asgard
Theory: 1973 C. R. Tom Gerald 2004 Hagen Kibble Guralnik David H. D. F. Wilczek Gross Politzer
Theory: Nambu, Peter François Jona-Lasinio 1961 Higgs Englert
1999 Gerard Martinus Robert
2008 't Hooft J. G. Veltman 2013 Brout Yoichiro Nambu Theory: Brout, Englert, Higgs, Guralnik, Hagen, Kibble, 1964 March 12, 2019 6 / 30 Asgardians for God Particle Basic Interactions and mediators
X
Gravity is not included in the SM Mediated by t n
e Gluons (g) r e f f i d
e r Photon (γ) a
s n
o + - i
t W , W , Z c a r e t n I Graviton (?) March 12, 2019 7 / 30 Asgardians for God Particle
Elementary Particles
Elementary: fundamental till date March 12, 2019 8 / 30 Asgardians for God Particle Elementary Particles
In SM neutrinos are massless
1 eV/c2 = 1.783×10−36 kg C = 1 in natural unit system
March 12, 2019 9 / 30 Muon S. Neddermeyer Electron The Particle Hunters (1936) (1897) Theory: Pauli, 1930 Tau e-Neutrino (1975) (1956) 1995 Martin Clyde C. D. Anderson Cowan 1995 1906 Lewis Perl Frederick m-Neutrino (1962) Carlo Rubbia Reines J. J. Thomson Theory: 1940 Theory: 1970 t-Neutrino (2000) Simon van der Meer DONUT Coll. 1984 1988 W+,W-,Z UA1, UA2 (1983) CERN Leon M. Melvin Jack Theory: Glashow, Weinberg, Salam, 1968 Steinberger Lederman Schwartz Theory: 1973 Gluons DORIS (1978) PETRA (1979) Light quarks DESY (up,down,strange) 2008 SLAC (1968) Theory: Gell-Mann, 1962 T. Maskawa M. Kobayashi 1976 Bottom quark Top quark FermiLAB CDF & D0 Burton Samuel (1977) Richter Ting (1995) 2013 1969 Charm quark Higgs boson Peter François Murray George SLAC,BNL (1974) ATLAS, CMS (2012) Higgs Englert Gell-Mann Zweig Theory: Glashow, LHC-CERN Theory: 1964 Iliopoulos,Maiani, 1970 Theory: Brout, Englert, Higgs, Guralnik, Hagen, Kibble, 1964 March 12, 2019 10 / 30 Inside Asgard of Particle Physics The Standard Model
Clients Postman
Interaction Mediators Acts on
Strong Gluons Quarks & Gluons
Letters Electromagnetic Photon Charged leptons, W, quarks Weak W, Z Leptons, Quarks W, Z, Higgs
March 12, 2019 11 / 30 The need of God Particle
Asgard of Particle Physics is ruled by symmetry laws
Those laws forbid mass terms
Most of the elementary particles are massive in nature !!
Asgard of Particle Physics seeks protection from symmetry Demons
March 12, 2019 12 / 30 When Symmetry Forbids
Consider the following English alphabets: M,N,O,P
1. Vertical mirror M M O O Reflection symmetry M, O survive
2. Horizontal mirror M O llll
Kii O Reflection symmetry M s oe Only O survives do try me mm Sy March 12, 2019 13 / 30 Observation: Asgard of Particle Physics is ruled by Gauge symmetries Mass terms are forbidden
Crisis: Most of the elementary particles and force mediators are massive
Solutions: Spontaneous symmetry breaking and ABEGHHK'tH mechanism
Thanks to God Particle March 12, 2019 14 / 30 Spontaneous symmetry breaking
Not the place of minimum Energy
Place of minimum Energy: Ground State
Will remain same under rotations
All directions on this Grey circle are the same from Pencil’s viewpoint Ground State is not unique
The ground state now has a SPECIFIC direction
The Rotational symmetry is Broken Spontaneously without any external influence
March 12, 2019 15 / 30 Spontaneous symmetry breaking in the SM GOD is Here
Unbroken symmetry
Spontaneously broken symmetry
“ GOD Particle’s ” Potential
March 12, 2019 16 / 30 When Massless becomes Massive: ABEGHHK'tH mechanism
W+ W- W3 B 4 X 2 + 4 =12 DOF Gauge Sector: All Massless with 2 DOF Unbroken gauge symmetries
H+ H- H0 Would be God
Higgs sector: Each with 1 DOF
Degrees Of Freedom: Independent Translation / Rotation / Vibration
March 12, 2019 17 / 30 When Massless becomes Massive: ABEGHHK'tH mechanism
Massless Photon with 2 DOF W+ W- Z0 γ
W3 W3 B B
Three Massive with 3 DOF each
Massive God Particle Spontaneously broken with 1 DOF gauge symmetries
3 X 3 + 2 + 1 =12 DOF match ✔
Leptons & Quarks masses through Yukawa interactions
Gluons remain massless March 12, 2019 18 / 30 What took it so long?
Electron (1897) J. J. Thomson J. J. Thomson 115 Years
Higgs boson (2012) Brout, , , Englert Higgs Guralnik, Hagen, Kibble March 12, 2019 19 / 30 From LEP to LHC: The quest for God Particle
Large Electron Positron Collider a.k.a LEP
Energy ~200 GeV e+ e- collider Length probed ~ 10-18 m 1989 - 2000 Insufcient energy to detect God Particle
Predicted Lower bound ~ 114 GeV
Energy ~2000 GeV 1987 - 2011 Length probed ~ 10-19 m Not a correct probe for God Particle p p collider Predicted Exclusion limits
With 1 GeV we can probe a distance of 10-15 m March 12, 2019 20 / 30 From LEP to LHC: The quest for God Particle
Large Hadron Collider a.k.a LHC Energy ~ 14000 GeV P P collider Length probed ~ 10-20 m
2010 - Discovery Machine Can not use for precision study
4th July 2012: CMS & ATLAS announced God Particle Discovery
The Saga of the SM Ends here ?
How large is 14 TeV ~ Kinetic Energy of a Ping-Pong ball (~3 gm) moving with a speed of ~4 cm/sec March 12, 2019 21 / 30 Eminence of the SM
Anomalous Magnetic Moment of muon
March 12, 2019 22 / 30 God Particle is here... It's All Over or NOT ?
Asgard of Particle Physics is complete now but is it SAFE ?
No it’s NOT !
March 12, 2019 23 / 30 God Particle itself is the most SERIOUS threat !
Suppose SM is the only theory for Particle Physics
It should work till 1019 GeV, a.k.a. Planck Scale, realm of GRAVITY
Quantum corrections Should make the Higgs much heavier than what it is
However, it’s ~125 GeV !
UNNATURAL FINE TUNING for Higgs Mass
It’s like a snowball surviving in hell March 12, 2019 24 / 30 Another troublesome Asgardian: Neutrino
Neutrinos are Massless within the SM
Neutrinos oscillate in nature: Observed
Takaaki Theory: Pontecorvo, 1957, 1967, Arthur Maki, Nakagawa, Sakata, 1962 McDonald Kajita
2015 Oscillation impossible WITHOUT Neutrino mass
Not within the SM March 12, 2019 25 / 30 Dark Matter: Enemy ‘beyond’ Asgard
Galaxies must have some massive non-luminous matter, i.e., DARK Matter
Beyond the LHC if anything matters, it is the Dark Matter which does matter... (anonymous)
Many more drawbacks of the SM are there... March 12, 2019 26 / 30 We NEED to look for a “BETTER” Asgard
March 12, 2019 27 / 30 Life at the LHC after God Particle
God Particle discovered but NOTHING ELSE since 2012
LHC will be back with 14 TeV at 2021
High-Luminosity (HL)-LHC from 2026
Proposed International Linear Collider (ILC) 500-1000 GeV, Precision studies
Proposed Compact Linear Collider (CLIC) Upto 3000 GeV, Precision studies Hope Survives Proposed Triple LEP Collider (TLEP) 80-100 km tunnel, 90-350 GeV, Precision studies
33 TeV, 100 TeV colliders Discovery machines March 12, 2019 28 / 30 God Particle discovery: Could be the beginning of a new journey
So far it seems like THIS IS THE ONE and NOTHING ELSE, but who knows... ?
This may be the ? tip of the iceberg... ? ? 125 GeV
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