82 research outputs found
Resilience of the Spectral Standard Model
We show that the inconsistency between the spectral Standard Model and the
experimental value of the Higgs mass is resolved by the presence of a real
scalar field strongly coupled to the Higgs field. This scalar field was already
present in the spectral model and we wrongly neglected it in our previous
computations. It was shown recently by several authors, independently of the
spectral approach, that such a strongly coupled scalar field stabilizes the
Standard Model up to unification scale in spite of the low value of the Higgs
mass. In this letter we show that the noncommutative neutral singlet modifies
substantially the RG analysis, invalidates our previous prediction of Higgs
mass in the range 160--180 Gev, and restores the consistency of the
noncommutative geometric model with the low Higgs mass.Comment: 13 pages, more contours added to Higgs mass plot, one reference adde
Higgs and Dark Matter Hints of an Oasis in the Desert
Recent LHC results suggest a standard model (SM)-like Higgs boson in the
vicinity of 125 GeV with no clear indications yet of physics beyond the SM. At
the same time, the SM is incomplete, since additional dynamics are required to
accommodate cosmological dark matter (DM). In this paper we show that
interactions between weak scale DM and the Higgs which are strong enough to
yield a thermal relic abundance consistent with observation can easily
destabilize the electroweak vacuum or drive the theory into a non-perturbative
regime at a low scale. As a consequence, new physics--beyond the DM
itself--must enter at a cutoff well below the Planck scale and in some cases as
low as O(10 - 1000 TeV), a range relevant to indirect probes of flavor and CP
violation. In addition, this cutoff is correlated with the DM mass and
scattering cross-section in a parameter space which will be probed
experimentally in the near term. Specifically, we consider the SM plus
additional spin 0 or 1/2 states with singlet, triplet, or doublet electroweak
quantum numbers and quartic or Yukawa couplings to the Higgs boson. We derive
explicit expressions for the full two-loop RGEs and one-loop threshold
corrections for these theories.Comment: 29 pages, 13 figure
Implications of the 125 GeV Higgs boson for scalar dark matter and for the CMSSM phenomenology
We study phenomenological implications of the ATLAS and CMS hint of a GeV Higgs boson for the singlet, and singlet plus doublet non-supersymmetric
dark matter models, and for the phenomenology of the CMSSM. We show that in
scalar dark matter models the vacuum stability bound on Higgs boson mass is
lower than in the standard model and the 125 GeV Higgs boson is consistent with
the models being valid up the GUT or Planck scale. We perform a detailed study
of the full CMSSM parameter space keeping the Higgs boson mass fixed to GeV, and study in detail the freeze-out processes that imply the observed
amount of dark matter. After imposing all phenomenological constraints except
for the muon we show that the CMSSM parameter space is divided
into well separated regions with distinctive but in general heavy sparticle
mass spectra. Imposing the constraint introduces severe tension
between the high SUSY scale and the experimental measurements -- only the
slepton co-annihilation region survives with potentially testable sparticle
masses at the LHC. In the latter case the spin-independent DM-nucleon
scattering cross section is predicted to be below detectable limit at the
XENON100 but might be of measurable magnitude in the general case of light dark
matter with large bino-higgsino mixing and unobservably large scalar masses.Comment: 17 pages, 7 figures. v3: same as published versio
Vacuum Stability, Perturbativity, and Scalar Singlet Dark Matter
We analyze the one-loop vacuum stability and perturbativity bounds on a
singlet extension of the Standard Model (SM) scalar sector containing a scalar
dark matter candidate. We show that the presence of the singlet-doublet quartic
interaction relaxes the vacuum stability lower bound on the SM Higgs mass as a
function of the cutoff and lowers the corresponding upper bound based on
perturbativity considerations. We also find that vacuum stability requirements
may place a lower bound on the singlet dark matter mass for given singlet
quartic self coupling, leading to restrictions on the parameter space
consistent with the observed relic density. We argue that discovery of a light
singlet scalar dark matter particle could provide indirect information on the
singlet quartic self-coupling.Comment: 25 pages, 10 figures; v2 - fixed minor typos; v3 - added to text
discussions of other references, changed coloring of figures for easier black
and white viewin
Multi-Scalar-Singlet Extension of the Standard Model - the Case for Dark Matter and an Invisible Higgs Boson
We consider a simple extension of the Standard Model by the addition of N
real scalar gauge singlets \vp that are candidates for Dark Matter. By
collecting theoretical and experimental constraints we determine the space of
allowed parameters of the model. The possibility of ameliorating the little
hierarchy problem within the multi-singlet model is discussed. The
Spergel-Steinhardt solution of the Dark Matter density cusp problem is
revisited. It is shown that fitting the recent CRESST-II data for Dark Matter
nucleus scattering implies that the standard Higgs boson decays predominantly
into pairs of Dark Matter scalars. It that case discovery of the Higgs boson at
LHC and Tevatron is impossible. The most likely mass of the dark scalars is in
the range 15 GeV \lsim \mvp \lsim 50 GeV with BR(h \to \vp\vp) up to 96%.Comment: 18 pages, 15 figure
Vacuum stability, neutrinos, and dark matter
Motivated by the discovery hint of the Standard Model (SM) Higgs mass around
125 GeV at the LHC, we study the vacuum stability and perturbativity bounds on
Higgs scalar of the SM extensions including neutrinos and dark matter (DM).
Guided by the SM gauge symmetry and the minimal changes in the SM Higgs
potential we consider two extensions of neutrino sector (Type-I and Type-III
seesaw mechanisms) and DM sector (a real scalar singlet (darkon) and minimal
dark matter (MDM)) respectively. The darkon contributes positively to the
function of the Higgs quartic coupling and can stabilize the
SM vacuum up to high scale. Similar to the top quark in the SM we find the
cause of instability is sensitive to the size of new Yukawa couplings between
heavy neutrinos and Higgs boson, namely, the scale of seesaw mechanism. MDM and
Type-III seesaw fermion triplet, two nontrivial representations of
group, will bring the additional positive contributions to the gauge coupling
renormalization group (RG) evolution and would also help to stabilize
the electroweak vacuum up to high scale.Comment: 18 pages, 15 figures; published versio
A survey of spectral models of gravity coupled to matter
This is a survey of the historical development of the Spectral Standard Model
and beyond, starting with the ground breaking paper of Alain Connes in 1988
where he observed that there is a link between Higgs fields and finite
noncommutative spaces. We present the important contributions that helped in
the search and identification of the noncommutative space that characterizes
the fine structure of space-time. The nature and properties of the
noncommutative space are arrived at by independent routes and show the
uniqueness of the Spectral Standard Model at low energies and the Pati-Salam
unification model at high energies.Comment: An appendix is added to include scalar potential analysis for a
Pati-Salam model. 58 Page
Sterile neutrino portal to Dark Matter II: exact dark symmetry
We analyze a simple extension of the standard model (SM) with a dark sector composed of a scalar and a fermion, both singlets under the SM gauge group but charged under a dark sector symmetry group. Sterile neutrinos, which are singlets under both groups, mediate the interactions between the dark sector and the SM particles, and generate masses for the active neutrinos via the seesaw mechanism. We explore the parameter space region where the observed Dark Matter relic abundance is determined by the annihilation into sterile neutrinos, both for fermion and scalar Dark Matter particles. The scalar Dark Matter case provides an interesting alternative to the usual Higgs portal scenario. We also study the constraints from direct Dark Matter searches and the prospects for indirect detection via sterile neutrino decays to leptons, which may be able to rule out Dark Matter masses below and around 100 GeV
RMDM and Lepton Flavor Violation
A model relating radiative seesaw and minimal dark matter mass scales without
beyond the standard model (SM) gauge symmetry (RMDM) is constructed. In
addition to the SM particles, the RMDM contains, a Majorana fermion
multiplet and scalar multiplet that transform respectively as
and under the SM gauge group . The neutral component plays the role of dark
matter with a mass in the range of 9 to 10 TeV. This scale also sets the lower
limit for the scale for the heavy degrees of freedom in and which
generate light neutrino masses through the radiative seesaw mechanism. The
model predicts an -nucleus scattering cross section that would be
accessible with future dark matter direct detection searches as well as
observable effects in present and searches for charged lepton flavor violating
processes, such as and conversion.Comment: Latex 18 pages with 7 figures. Discussions added in dark matter
section and a few references adde
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