Z’ Mediation of Supersymmetry Breaking. Itay Yavin Princeton University. arXiv:0710.1632 [hepph]  G. Paz, P. Langacker, L. Wang and IY arXiv:0801.3693 [hepph]  G. Paz, P. Langacker, L. Wang and IY arXiv:0711.3214 [hepth]  H. Verlinde , L. Wang, M. Wijnholt and IY. Outline. Motivation
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Itay Yavin
Princeton University
arXiv:0710.1632 [hepph] G. Paz, P. Langacker, L. Wang and IY
arXiv:0801.3693 [hepph] G. Paz, P. Langacker, L. Wang and IY
arXiv:0711.3214 [hepth] H. Verlinde , L. Wang, M. Wijnholt and IY
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The Forces of NatureElectromagnetic force
Strong force
Atoms ~ 1010 m
Weak force
Protons and Neutrons
~ 1015 m
Radioactive decay
~ 1018 m
Why is the weak force stronger than gravity?
Are there any other forces?
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Supersymmetry (an extended spacetime sym.)
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None of the degrees of freedom associated with these symmetries are seen at low energies. Following the paradigm of SUSY breaking in a hidden sector (see H. P. Nilles talk) we propose the following scenario
U’(1) and EWSB is dynamically generated.
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An abelian gauge field can mix with the RRform in the gravitational multiplet. The RRform propagates in the bulk and can act to mix two U(1)’s on remote branes.
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Assume that only matter on the visible brane participate in the anomaly cancellation conditions.
Also, allow for the following coupling of the singlet field,
D, Dc are colored exotics.
E, Ec are color singlet exotics.
Solving for the anomaly cancellation conditions:
Two free charges Q2 and QQand nD = 3, nE = 2.
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The gauginos are not charged under the new force and don’t directly interact with it. Nonetheless, they feel it quantum mechanically,
The scalars are at roughly 100 TeV and so finetuning is inevitable. This is a miniversion of the split SUSY scenario,
N. ArkaniHamed, S.~Dimopoulos, hepth/0405159
G. Giudice and A. Romanino, hepph/0406088
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DynamicsThe singlet must break the U’(1) gaugesymmetry in the visible sector, generate a term, and give the exotics a mass.
+
(positive contribution)
(negative contribution)
Singlet’s U’(1) charge cannot be too large.
Yukawa coupling to exotics cannot be too small
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mS sets the masses of the Z’ gaugeboson and the singlino’s
EWSB varyingS we can finetune one against the other
The two Higgs doublet mass matrix is,
Note: This tuning leads to some amount of accidental tuning:
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S
MZ’
~
V(S)
Matter scalar partners
S
Energy ScalesSupersymmetry is broken. Only the Z’ vector supermultiplet feels the breaking directly.
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The red dots represent charge assignment for which a viable solution for the Electroweak scale. The Yukawa were chosen to be,
= yD = 0.5 yE = 0.1
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The physical Higgs mass is determined by the quartic,
But, the quartic is determined by the boundary condition and the RGE, which don’t change appreciably in the model we consider,
So the Higgs mass is almost entirely determined by the running from 1000 TeV down to the Electroweak scale,
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Since all the scalar partners are heavy, the gluino must decay through an offshell intermediate scalar,
We may never be able to resolve the intermediate particle, but we may observe the long lifetime of the gluino!
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The parametric dependence of the two processes is very different.
Gambino, Giudice and Slavich arXiv:hepph/0506214
Arvanitaki et al arXiv:hepph/0506242.
Lifetime for different benchmark points.
Similar calculations in the context of split susy were done by Toharia and Wells arXiv:hepph/0503175
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~
t
~
g

~
t
N1
Glueballino and other exotic HadronsThe gluino is long lived, but not long enough to leave a displaced vertex. It will first hadronize and then decay,
g
u
d
g
Hadronic bound state.
Is there any way to experimentally distinguish between a gluon that decay before or after hadronizing?
Grossman and Nachshon  arXiv:0803.1787 [hepph]
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mll2
Crosssection
(pb)
Z’ ProductionIf a new force is indeed waiting to be discovered, then we may just observe its carrier directly at the LHC,
Too many refs. . .
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After its discovery it will be easier to explore the other decay modes of the heavy vectorboson.
The collider signatures have not been thoroughly investigated yet, hopefully in the near future . . .
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PredictionsSUSY08
Dark matter remains a problem in this type of scenario. When the wino is the LSP the density is too low. If either the singlino or gravitino are the LSP it is usually a disaster. Any way out?
Unification: not present in the current model. Work in progress. . . seems difficult (Axions).
In this setup we assumed UV boundary conditions analogues to gauginomediation. How do things change if we were to consider a gaugemediation type setup?
Including more details of the hidden sector.
A more extensive study of realizations of such a setup in the context of string theory. But see: Grimm and Klemm arXiv; 0805.3361[hepth].
Any connection with the landscape?
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ConclusionsOur current best speculations about the UV almost always lead to the existence of additional U’(1) gauge fields at low energies. This may fit nicely as a (bulk) mediator of SUSY breaking.
The resulting model is dynamical, calculable and predictive.
3) The general features are quite robust and lead to distinct signatures. With some luck we’ll be able to see it at the LHC!!!
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Radioactivity was observed before the discovery of the electron. We are still trying to uncover the nature of the weak force. It may be instructive to recall that it took about 30 years before scientists figured out what Beta decay was all about:
Experimental difficulties and confusion: “. . . The ignorance at the time about the relation between the blackening of a photographic plate and the intensity of the irradiation.”(Pais, Inward Bound)
Theoretical misunderstanding and prejudices: “ . . . Prevailing prejudice still strongly favoured a discrete spectrum possibly due to a monoenergetic primary source.”(Pais)
Real physics: discrete lines in the spectrum due to (the yet undiscovered) nuclear structure.
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“Of course, it may be that someone will come up soon with a solution to the problem of the meson, and that experimental results will confirm so many detailed features of the theory that it will be clear to everybody that it is the correct one. Such things have happened in the past. They may happen again. However, I do not believe that we can count on it, and I believe that we must be prepared for a long, hard pull.” (E. Fermi, Collected works, paper 247)
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The gravitino mass is given as usual,
But, the SUSY breaking scale is very sensitive to the precise details of the model,
Hard to predict. Need more details about the hidden sector and the precise mechanism of SUSY breaking.
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Will be induced at loop level. Consider the superpotential,
By construction k does not have an Fterm. It’s lowest component is roughly,
Which will induce kinetic mixing. However, since in the limit that M1 vanishes there is chiral symmetry protecting it so,
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