10,937 research outputs found
Radiative Electroweak Symmetry Breaking from a Quasi-Localized Top Quark
We consider 5D supersymmetric SU(3) x SU(2) x U(1) theories compactified at
the TeV scale on S^1/Z_2 with supersymmetry broken by boundary conditions.
Localizing the top quark at a boundary of a fifth dimension by a bulk mass term
M_t, reduces the strength of radiative electroweak symmetry breaking. For M_t R
approximately 1--2, the natural value for the top and bottom squark masses are
raised to 500--1200 GeV, and all other superpartners may have masses of the
compactification scale, which has a natural range of 1/R ~= 1.5--3.5 TeV. The
superpartner masses depend only on 1/R, and are precisely correlated amongst
themselves and with the mass of the Higgs boson, which is lighter than 130 GeV.Comment: 23 pages, 8 figures, Latex; typos correcte
1-motivic sheaves and the Albanese functor
We introduce n-generated sheaves and n-motivic sheaves, describing completely
for n = 0, 1 and proposing a conjecture for n > 1. We then obtain functors
L\pi_0 and LAlb on DM_{eff}(k) deriving \pi_0 and Alb. The functor LAlb extends
the one constructed (by the second author jointly with B.Kahn) to
non-necessarily geometric motives. These functors are then used to define
higher N\'eron-Severi groups and higher Albanese sheaves. The latter may be
considered as an algebraic avatar of Deligne (co)homology.Comment: 54 pages, fully revised exposition with a new "structure theorem" for
1-motivic sheaves, see Theorem 1.3.10, including finitely presented (or
constructible) 1-motivic sheave
Fermion masses and symmetry breaking of a U(2) flavour symmetry
We show how a specific sequential breaking pattern of a U(2) flavour symmetry
occurs automatically in a broad framework. The relative orientation in U(2)
space of the spurion fields that breaks the U(2) symmetry is uniquely fixed,
thus determining the form of the fermion mass matrices in a predictive way.Comment: 9 pages, uses amsmath.st
Minimal Mirror Twin Higgs
In a Mirror Twin World with a maximally symmetric Higgs sector the little
hierarchy of the Standard Model can be significantly mitigated, perhaps
displacing the cutoff scale above the LHC reach. We show that consistency with
observations requires that the Z2 parity exchanging the Standard Model with its
mirror be broken in the Yukawa couplings. A minimal such effective field
theory, with this sole Z2 breaking, can generate the Z2 breaking in the Higgs
sector necessary for the Twin Higgs mechanism. The theory has constrained and
correlated signals in Higgs decays, direct Dark Matter Detection and Dark
Radiation, all within reach of foreseen experiments, over a region of parameter
space where the fine-tuning for the electroweak scale is 10-50%. For dark
matter, both mirror neutrons and a variety of self-interacting mirror atoms are
considered. Neutrino mass signals and the effects of a possible additional Z2
breaking from the vacuum expectation values of B-L breaking fields are also
discussed.Comment: 42 pages, 8 figures; additional references and discussion on higgs
physics and dark matte
Mirror World at the Large Hadron Collider
A mirror world can modify in a striking way the LHC signals of the Higgs
sector. An exact or approximate Z_2 symmetry between the mirror world and our
world allows large mixing between the Higgs bosons of these worlds, leading to
production rates and branching ratios for these states that are markedly
different from the standard model and are characteristic of a mirror world. The
constraints on these Higgs boson masses from precision electroweak data differ
from the standard model bound, so that the new physics that cancels the
quadratic divergence induced by the top quark may appear at a larger scale,
possibly beyond the reach of the LHC. However, the scale of new physics needed
to cancel the quadratic divergence induced by the Higgs boson is not
significantly changed. With small breakings of the Z_2 parity, the lightest
mirror quarks (and possibly charged mirror leptons) could be the dark matter in
the universe, forming galactic halos that are stable to cooling. A possible
signal from the relic radiation density of the mirror world is also discussed.Comment: 15 pages, 1 figur
A Constrained Standard Model: Effects of Fayet-Iliopoulos Terms
In hep-ph/0011311 the one Higgs doublet standard model was obtained by an
orbifold projection of a 5D supersymmetric theory in an essentially unique way,
resulting in a prediction for the Higgs mass m_H = 127 \pm 8 GeV and for the
compactification scale 1/R = 370 \pm 70 GeV. The dominant one loop contribution
to the Higgs potential was found to be finite, while the above uncertainties
arose from quadratically divergent brane Z factors and from other higher loop
contributions. In hep-th/0108184, a quadratically divergent Fayet-Iliopoulos
term was found at one loop in this theory. We show that the resulting
uncertainties in the predictions for the Higgs boson mass and the
compactification scale are small, about 25% of the uncertainties quoted above,
and hence do not affect the original predictions. However, a tree level brane
Fayet-Iliopoulos term could, if large enough, modify these predictions,
especially for 1/R.Comment: 7 pages, LaTeX, Contribution to "Summer Institute 2001",
Fuji-Yoshida, Japan, August 200
The Neron-Severi group of a proper seminormal complex variety
We prove a Lefschetz (1,1)-Theorem for proper seminormal varieties over the
complex numbers. The proof is a non-trivial geometric argument applied to the
isogeny class of the Lefschetz 1-motive associated to the mixed Hodge structure
on H^2.Comment: 16 pages; Mathematische Zeitschrift (2008
Nori 1-motives
Let EHM be Nori's category of effective homological mixed motives. In this
paper, we consider the thick abelian subcategory EHM_1 generated by the i-th
relative homology of pairs of varieties for i = 0,1. We show that EHM_1 is
naturally equivalent to the abelian category M_1 of Deligne 1-motives with
torsion; this is our main theorem. Along the way, we obtain several interesting
results. Firstly, we realize M_1 as the universal abelian category obtained,
using Nori's formalism, from the Betti representation of an explicit diagram of
curves. Secondly, we obtain a conceptual proof of a theorem of Vologodsky on
realizations of 1-motives. Thirdly, we verify a conjecture of Deligne on
extensions of 1-motives in the category of mixed realizations for those
extensions that are effective in Nori's sense
- …