1,615 research outputs found
CP violating dimuon charge asymmetry in general left-right models
The recently measured charge asymmetry of like-sign dimuon events by the D0
collaboration at Tevatron shows the 3.9 \sigma\ deviation from the standard
model prediction. In order to solve this mismatch, we investigate the
right-handed current contributions to and
mixings which are the major source of the like-sign dimuon events in production in general left-right models without imposing manifest or
pseudo-manifest left-right symmetry. We find the allowed region of new physics
parameters satisfying the current experimental data.Comment: 9 pages, 4 figure
Singlet Fermionic Dark Matter with Dark
We present a fermionic dark matter model mediated by the hidden gauge boson.
We assume the QED-like hidden sector which consists of a Dirac fermion and
U(1) gauge symmetry, and introduce an additional scalar electroweak doublet
field with the U(1) charge as a mediator. The hidden U(1) symmetry is
spontaneously broken by the electroweak symmetry breaking and there exists a
massive extra neutral gauge boson in this model which is the mediator between
the hidden and visible sectors. Due to the U(1) charge, the additional
scalar doublet does not couple to the Standard Model fermions, which leads to
the Higgs sector of type I two Higgs doublet model. The new gauge boson couples
to the Standard Model fermions with couplings proportional to those of the
ordinary boson but very suppressed, thus we call it the dark boson. We
study the phenomenology of the dark boson and the Higgs sector, and show
the hidden fermion can be the dark matter candidate.Comment: 10 pages, 3 figure
Phenomenology of a two-component dark matter model
We study a two-component dark matter model consisting of a Dirac fermion and
a complex scalar charged under new U(1) gauge group in the hidden sector. The
dark fermion plays the dominant component of dark matter which explains the
measured DM relic density of the Universe. It has no direct coupling to
ordinary standard model particles, thus evading strong constraints from the
direct DM detection experiments. The dark fermion is self-interacting through
the light dark gauge boson and it would be possible to address that this model
can be a resolution to the small scale structure problem of the Universe. The
light dark gauge boson, which interacts with the standard model sector, is also
stable and composes the subdominant DM component. We investigate the model
parameter space allowed by current experimental constraints and
phenomenological bounds. We also discuss the sensitivity of future experiments
such as SHiP, DUNE and ILC, for the obtained allowed parameter space.Comment: 13 pages, 1 figure, journal versio
Vacuum stability of conformally invariant scalar dark matter models
We discuss vacuum structure and vacuum stability in classically
scale-invariant renormalizable models with a scalar dark matter multiplet of
global O(N) symmetry together with an electroweak singlet scalar mediator. Our
conformally invariant scalar potential generates the electroweak symmetry
breaking via the Coleman-Weinberg mechanism, and the new scalar singlet
mediator acquires its mass through radiative corrections of the scalar dark
matters as well as of the standard model particles. Taking into account the
present collider bounds, we find the region of parameter space where the scalar
potential is stable and all the massless couplings are perturbative up to the
Planck scale. With the obtained parameter sets satisfying the vacuum stability
condition, we present the allowed region of new physics parameters satisfying
the recent measurement of relic abundance, and predict the elastic scattering
cross section of the new scalar multiplet into target nuclei for a direct
detection of the dark matter. We also discuss the collider signatures and
future discovery potentials of the new scalars.Comment: 11 pages, 6 figures (partly updated), journal version. arXiv admin
note: text overlap with arXiv:1904.1020
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