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226
Jumping Through Loops: On Soft Terms from Large Volume
 Compactifications, JHEP
"... We subject the phenomenologically successful large volume scenario of hepth/0502058 to a first consistency check in string theory. In particular, we consider whether the expansion of the string effective action is consistent in the presence of Dbranes and Oplanes. Due to the noscale structure at ..."
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We subject the phenomenologically successful large volume scenario of hepth/0502058 to a first consistency check in string theory. In particular, we consider whether the expansion of the string effective action is consistent in the presence of Dbranes and Oplanes. Due to the noscale structure at treelevel, the scenario is surprisingly robust. We compute the modification of soft supersymmetry breaking terms, and find only subleading corrections. We also comment that for largevolume limits of toroidal orientifolds and fibered CalabiYau manifolds the corrections can be more important,
Multidimensional mSUGRA likelihood maps
 Phys. Rev. D 73 (2006) 015013 [arXiv:hepph/0507283]. 27
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Direct Mediation and a Visible Metastable Supersymmetry Breaking Sector
 JHEP
"... Abstract: We analyze an Rsymmetry breaking deformation of the ISS model for a direct mediation of supersymmetry breaking from a metastable vacuum. The model is weakly coupled and calculable. The LSP gravitino is light (m3 < 16eV) and the MSSM spectrum 2 is natural with a light Higgs. The supersy ..."
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Abstract: We analyze an Rsymmetry breaking deformation of the ISS model for a direct mediation of supersymmetry breaking from a metastable vacuum. The model is weakly coupled and calculable. The LSP gravitino is light (m3 < 16eV) and the MSSM spectrum 2 is natural with a light Higgs. The supersymmetry breaking sector, which is usually hidden, is observable (m ∼ 1TeV) and may be a candidate for cold dark matter. We discuss its production and signature at LHC. We propose a UV completion of the model in terms of a duality cascade.
Hunting Dark Matter GammaRay Lines with the Fermi
 LAT,” JCAP 1105 (2011) 027 [arXiv:1101.2610 [hepph
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Vacuum Instabilities with a WrongSign HiggsGluonGluon Amplitude
"... The recently discovered 125 GeV boson appears very similar to a Standard Model Higgs, but with data favoring an enhanced h → γγ rate. A number of groups have found that fits would allow (or, less so after the latest updates, prefer) that the ht t ̄ coupling have the opposite sign. This can be given ..."
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The recently discovered 125 GeV boson appears very similar to a Standard Model Higgs, but with data favoring an enhanced h → γγ rate. A number of groups have found that fits would allow (or, less so after the latest updates, prefer) that the ht t ̄ coupling have the opposite sign. This can be given meaning in the context of an electroweak chiral Lagrangian, but it might also be interpreted to mean that a new colored and charged particle runs in loops and produces the oppositesign hGG amplitude to that generated by integrating out the top, as well as a contribution reinforcing the Wloop contribution to hF F. In order to not suppress the rate of h→WW and h → ZZ, which appear to be approximately Standard Modellike, one would need the loop to “overshoot, ” not only canceling the top contribution but producing an oppositesign hGG vertex of about the same magnitude as that in the SM. We argue that most such explanations have severe problems with finetuning and, more importantly, vacuum stability. In particular, the case of stop loops producing an oppositesign hGG vertex of the same size as the Standard Model one is ruled out by a combination of vacuum decay bounds and LEP constraints. We also show that scenarios with a sign flip from loops of color octet charged scalars or new fermionic states are highly constrained. 1
The BL/Electroweak Hierarchy
 in Smooth Heterotic Compactifications,” Int.J.Mod.Phys. A25:26312677,2010 [ arXiv:0910.1129 [hepth
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Perturbative Critical Behavior from Spacetime Dependent Couplings
"... We find novel perturbative fixed points by introducing mildly spacetimedependent couplings into otherwise marginal terms. In fourdimensional QFT, these are physical analogues of the smallǫ WilsonFisher fixed point. Rather than considering 4 − ǫ dimensions, we stay in four dimensions but introduc ..."
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We find novel perturbative fixed points by introducing mildly spacetimedependent couplings into otherwise marginal terms. In fourdimensional QFT, these are physical analogues of the smallǫ WilsonFisher fixed point. Rather than considering 4 − ǫ dimensions, we stay in four dimensions but introduce couplings whose leading spacetime dependence is of the form λxκµκ, with a small parameter κ playing a role analogous to ǫ. We show, in φ4 theory and in QED and QCD with massless flavors, that this leads to a critical theory under perturbative control over an exponentially wide window of spacetime positions x. The exact fixed point coupling λ∗(x) in our theory is identical to the running coupling of the translationally invariant theory, with the scale replaced by 1/x. Similar statements hold for threedimensional φ6 theories and twodimensional sigma models with curved target spaces. We also describe strongly coupled examples using conformal perturbation theory.
The Higgs sector of supersymmetric theories and the implications for highenergy colliders
 arXiv:0810.2439 [hepph]; S. Heinemeyer, Higgs Physics at the LHC: Some Theory Aspects, arXiv:0807.2514 [hepph
"... One of the main motivations for low energy supersymmetric theories is their ability to address the hierarchy and naturalness problems in the Higgs sector of the Standard Model. In these theories, at least two doublets of scalar fields are required to break the electroweak symmetry and to generate th ..."
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One of the main motivations for low energy supersymmetric theories is their ability to address the hierarchy and naturalness problems in the Higgs sector of the Standard Model. In these theories, at least two doublets of scalar fields are required to break the electroweak symmetry and to generate the masses of the elementary particles, resulting in a rather rich Higgs spectrum. The search for the Higgs bosons of Supersymmetry and the determination of their basic properties is one of the major goals of high–energy colliders and, in particular, the LHC which will soon start operation. We review the salient features of the Higgs sector of the Minimal Supersymmetric Standard Model and of some of its extensions and summarize the prospects for probing them at the LHC and at the future ILC. In memoriam of Julius Wess, 1934–2007. To be published in ”Supersymmetry on the Eve of the LHC ” a special volume of European Physical Journal C, It was known relatively soon after the introduction of the Standard Model (SM) of the electroweak
A Shift Symmetry in the Higgs Sector: Experimental Hints and Stringy Realizations
"... We interpret reported hints of a Standard Model Higgs boson at ∼ 125 GeV in terms of highscale supersymmetry breaking with a shift symmetry in the Higgs sector. More specifically, the Higgs mass range suggested by recent LHC data extrapolates, within the (nonsupersymmetric) Standard Model, to a va ..."
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We interpret reported hints of a Standard Model Higgs boson at ∼ 125 GeV in terms of highscale supersymmetry breaking with a shift symmetry in the Higgs sector. More specifically, the Higgs mass range suggested by recent LHC data extrapolates, within the (nonsupersymmetric) Standard Model, to a vanishing quartic Higgs coupling at a UV scale between 106 and 1018 GeV. Such a small value of λ can be understood in terms of models with highscale SUSY breaking if the Kähler potential possesses a shift symmetry, i.e., if it depends on Hu and Hd only in the combination (Hu + Hd). This symmetry is known to arise rather naturally in certain heterotic compactifications. We suggest that such a structure of the Higgs Kähler potential is common in a wider class of string constructions, including intersecting D7 and D6brane models and their extensions to Ftheory or Mtheory. The latest LHC data may thus be interpreted as hinting to a particular class of compactifications which possess this shift symmetry. ar X iv
UW/PT01/14 Ineffective Supersymmetry: Electroweak Symmetry Breaking from Extra Dimensions
, 2001
"... Recently, a mechanism for electroweak symmetry breaking (EWSB) was discussed [1], in which the scale of EWSB is set by the scale of an additional dimension R ∼ TeV −1. The mechanism involves supersymmetry, but broken in such a fashion that high (fourdimensional) momentum loops are cut off by the fi ..."
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Recently, a mechanism for electroweak symmetry breaking (EWSB) was discussed [1], in which the scale of EWSB is set by the scale of an additional dimension R ∼ TeV −1. The mechanism involves supersymmetry, but broken in such a fashion that high (fourdimensional) momentum loops are cut off by the finite size of the radius. In a KaluzaKlein decomposition, a hard cutoff seems to give a strong cutoff dependence, while summing the entire tower is not only cutoff insensitive, but actually finite. Such behavior is easily understood in a formulation that respects fivedimensional locality. Finally, we note that certain models of this type naturally give operators which can “fake” A central question in particle physics is this: what is the origin of the scale of electroweak symmetry breaking, and what stabilizes it against radiative corrections? In the past two decades, a tremendous amount of effort has gone into answering this question, and exploring the implications of possible answers. This “hierarchy problem ” is summed up simply: why is MW ≪ MPl?