LECTURE 2: Super theories

Transcription

1 LECTURE 2: Super theories Carlos Muñoz Universidad Autónoma de Madrid & Instituto de Física Teórica UAM/CSIC ISAPP09-Como, July 8-16

2 Carlos Muñoz Super theories 2

3 ~ Carlos Muñoz Super theories 3

4 Although recall that it does not have candidates for dark matter (see lecture 1) Carlos Muñoz Super theories 4

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6 Superkamiokande contains 45,000 tons of water and 10,000 photomultipliers Fortunately: p (susy) > p (no susy)

7 More advantages of SUSY In addition to have dark matter candidates: Unification scale is consistent with LEP data Allows to solve the hierarchy problem (why m H is not of order M planck?) Allows to understand how the electroweak symmetry, SU(2) L xu(1) Y, is broken It has a prediction that can be easily tested at the LHC: m h < 135 GeV Its local version gives rise to a theory of gravity: Supergravity It seems to be a crucial ingredient of string theory Carlos Muñoz Super theories 7

8 m SUSY ~ 1 TeV Carlos Muñoz Super theories 8

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10 generated once SUSY is broken and therefore SUSY masses must be ~TeV Carlos Muñoz Super theories 10

11 But SUSY has also several problems How to break SUSY in order to generate masses for SUSY particles Dangerous baryon and lepton number violation operators µ problem Dangerous charge and colour breaking minima... Carlos Muñoz Super theories 11

12 On experimental grounds SUSY cannot be an exact symmetry of Nature: SUSY partners of the known particles with the same masses has not been detected e.g. scalar electrons with masses of 0.5 MeV In global SUSY one simply introduces terms in the Lagrangian which explicitly break SUSY, without inducing quadratic divergences: soft terms m, M, A, B A popular approach uses a hidden sector In supergravity, the breaking of local SUSY generates the soft terms, and these can be computed Carlos Muñoz Super theories 12

13 Baryon and lepton number violation e.g. operators like d c d c u c, QLd c are allowed in the superpotential Too fast proton decay q l q ~ q q To preserve B and L conservation one can impose a discrete symmetry (R parity) Particle Particle Superpartner Superpartner In models with R parity the LSP is stable since e.g.: Thus it is a candidate for dark matter Carlos Muñoz Super theories ~ e ~ e

14 The µ problem There are several solutions, e.g.: µ H 1 H 2 S H 1 H 2 µ eff = <S> NMSSM R H 1 H 2 µ eff = < R > SSM Carlos Muñoz Super theories 14

15 Charge and colour breaking In supersymmetry there are scalar fields with colour and electric charge Enormous complexity of V This induces the possible existence of dangerous Charge and Colour Breaking (CCB) Minima: Carlos Muñoz Super theories 15

16 More advantages of SUSY In addition to have dark matter candidates: Unification scale is consistent with LEP data Allows to solve the hierarchy problem (why m H is not of order M planck?) Allows to understand how the electroweak symmetry, SU(2) L xu(1) Y, is broken It has also a prediction that can be easily tested at the LHC: m h < 130 GeV Its local version gives rise to a theory of gravity: Supergravity It seems to be a crucial ingredient of string theory Carlos Muñoz Super theories 16

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24 Including vector supermultiplets: Carlos Muñoz Super theories 24

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28 But SUGRA has also several problems Carlos Muñoz Super theories 28

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