A
bstract
If neutrinos are Dirac fermions, certain new physics beyond the standard model should exist to account for the smallness of neutrino mass. With two additional scalars and a heavy ...intermediate fermion, in this paper, we systematically study the general mechanism that can naturally generate the tiny Dirac neutrino mass at tree and in one-loop level. For tree level models, we focus on natural ones, in which the additional scalars develop small vacuum expectation values without fine-tuning. For one-loop level models, we explore those having dark matter candidates under
Z
2
D
symmetry. In both cases, we concentrate on SU(2)
L
multiplet scalars no larger than quintuplet, and derive the complete sets of viable models. Phenomenologies, such as lepton flavor violation, leptogenesis, DM and LHC signatures are briefly discussed.
In this paper, we propose a viable approach to realise two texture-zeros in the scotogenic model with flavor dependent
U
(
1
)
B
-
2
L
α
-
L
β
gauge symmetry. These models are extended by two ...right-handed singlets
N
Ri
and two inert scalar doublets
η
i
, which are odd under the dark
Z
2
symmetry. Among all the six constructed textures, texture
A
1
and
A
2
are the only two allowed by current experimental limits. Then choosing texture
A
1
derived from
U
(
1
)
B
-
2
L
e
-
L
τ
, we perform a detail analysis on the corresponding phenomenology such as predictions of neutrino mixing parameters, lepton flavor violation, dark matter and collider signatures. One distinct nature of such model is that the structure of Yukawa coupling
L
¯
η
~
N
R
is fixed by neutrino oscillation data, and can be further tested by measuring the branching ratios of charged scalars
η
1
,
2
±
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The B-L scotogenic models for Dirac neutrino masses Wang, Weijian; Wang, Ruihong; Han, Zhi-Long ...
The European physical journal. C, Particles and fields,
12/2017, Letnik:
77, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of
U
(
1
)
B
-
L
extensions of standard model. It is indicated that the total number of ...intermediate fermion singlets is uniquely fixed by the anomaly free condition and the new particles may have exotic
B
-
L
charges so that the direct SM Yukawa mass term
ν
¯
L
ν
R
ϕ
0
¯
and the Majorana mass term
(
m
N
/
2
)
ν
R
C
¯
ν
R
are naturally forbidden. After the spontaneous breaking of the
U
(
1
)
B
-
L
symmetry, the discrete
Z
2
or
Z
3
symmetry appears as the residual symmetry and gives rise to the stability of intermediate fields as DM candidates. Phenomenological aspects of lepton flavor violation, DM, leptogenesis and LHC signatures are discussed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
In this work, we make a detailed discussion on the phenomenology of the scotogenic Dirac model, which could accommodate the Dirac neutrino mass and dark matter. We have studied the ...lepton-flavor-violating (LFV) processes in this model, which are mediated by the charged scalar
ϕ
±
and heavy Dirac fermions
N
i
. The experimental bounds, especially given by decays
μ → eγ
and
μ →
3
e
, have put severe constraints on the Yukawa couplings
y
Φ
and masses
m
N
1
,
m
ϕ
. We select the heavy Dirac fermion
N
1
as dark matter candidate and find the correct relic density will be reached basically by annihilating through another Yukawa coupling
y
χ
. After satisfying LFV and dark matter relic density constraints, we consider the indirect detections of dark matter annihilating into leptons. But the constraints are relatively loose, only the
τ
+
τ
−
channel can impose a mild excluding capability. Then we make a detailed discussion on the dark matter direct detections. Although two Yukawa couplings can both contribute to the direct detection processes, more attention has been paid on the
y
Φ
-related processes as the
y
χ
-related process is bounded loosely. The current and future direct detection experiments have been used to set constraints on the Yukawa couplings and masses. The current direct detections bounds are relatively loose and can barely exclude more parameter region beyond the LFV. For the future direct detection experiments, the excluding capacities can be improved due to larger exposures. The detecting capabilities in the large mass region have not been weakened as the existence of mass enhancement from the magnetic dipole operator
O
mag
.
. At last, we have briefly discussed the collider signal searching in this model, the most promising signature is pair produced
ϕ
+
ϕ
−
and decay into the signal of
ℓ
+
ℓ
−
+
Ɇ
T
. The exclusion limits from collider on
m
N
1
and
m
ϕ
have provided a complementary detecting capability compared to the LFV and dark matter detections.
In the light of the
e
+
+
e
-
excess observed by DAMPE experiment, we propose an anomaly-free radiative seesaw model with an alternative leptophilic
U
(
1
)
X
gauge symmetry. In the model, only ...right-handed leptons are charged under
U
(
1
)
X
symmetry. The tiny Dirac neutrino masses are generated at one-loop level and charged leptons acquire masses though the type-I seesaw-like mechanism with heavy intermediate fermions. In order to cancel the anomaly, irrational
U
(
1
)
X
charge numbers are assigned to some new particles. After the spontaneous breaking of
U
(
1
)
X
symmetry, the dark
Z
2
symmetry could appear as a residual symmetry such that the stability of inert particles with irrational charge numbers are guaranteed, naturally leading to stable DM candidates. We show that the Dirac fermion DM contained in the model can explain the DAMPE excess. Meanwhile, experimental constraints from DM relic density, direct detection, LEP and anomalous magnetic moments are satisfied.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, we thoroughly investigate the LHC phenomenology of the type II seesaw mechanism for neutrino masses in the non-degenerate case where the triplet scalars of various charge have ...different masses. Compared with the degenerate case, the cascade decays of scalars lead to many new, interesting signal channels. In summary, with an integrated luminosity (ProQuest: Formulae and/or non-USASCII text omitted), the triplet scalars can be fully reconstructed at 14 TeV LHC in the negative scenario.
This brief concerns the problem of false data injection (FDI) attacks against partial sensor measurements of a networked stochastic system. For a Kalman filter based output tracking control system ...with a residual-based anomaly detector, a partial FDI attack strategy is presented to deteriorate the system performance by injecting false signals into the feedback communication channel to tamper partial sensor measurements. The stealthiness condition of the attack as well as its impact on the closed-loop system is derived, which are quite different from those of the FDI attack against all sensor measurements given in the existing work. This may be helpful for guaranteeing the secure control of a networked system by protecting partial critical sensor measurements from FDI attacks. Two numerical examples are included to verify the theoretical results.
A
bstract
We study how the dominant single and double SM-like Higgs (
h
) production at future
e
+
e
−
colliders is modified in the Georgi-Machacek (GM) model. On imposing theoretical, indirect and ...direct constraints, significant deviations of
h
-couplings from their SM values are still possible; for instance, the Higgs-gauge coupling can be corrected by a factor
κ
hV V
∈ 0
.
93
,
1
.
15 in the allowed parameter space. For the Higgs-strahlung
e
+
e
−
→
hZ
and vector boson fusion processes
e
+
e
−
→
h
ν
ν
¯
, he
+
e
−
, the cross section could increase by 32% or decrease by 13%. In the case of associated production with a top quark pair
e
+
e
−
→
h
t
t
¯
, the cross section can be enhanced up to several times when the custodial triplet scalar
H
3
0
is resonantly produced. In the meanwhile, the double Higgs production
e
+
e
−
→
h
h
Z
h
h
ν
ν
¯
can be maximally enhanced by one order of magnitude at the resonant
H
1,3
0
production. We also include exclusion limits expected from future LHC runs at higher energy and luminosity and discuss their further constraints on the relevant model parameters. We find that the GM model can result in likely measurable deviations of Higgs production from the SM at future
e
+
e
−
colliders.
A
bstract
The Scotogenic model extends the standard model with three singlet fermion
N
i
and one inert doublet scalar
η
to address the common origin of tiny neutrino mass and dark matter. For fermion ...dark matter
N
1
, a hierarchical Yukawa structure
∣
y
1
e
∣
≪
∣
y
1
μ
∣
∼
∣
y
1
τ
∣
∼
O
1
is usually favored to satisfy constraints from lepton flavor violation and relic density. Such large
μ
-related Yukawa coupling would greatly enhance the pair production of charged scalar
η
±
at the muon collider. In this paper, we investigate the dilepton and mono-photon signature of the Scotogenic model at a 14 TeV muon collider. For the dimuon signature
, we find that most viable samples can be probed with 200 fb
−
1
data. The ditau signature
is usually less promising, but it is important to probe the small
|y
1
μ
|
region. The mono-photon signature
could also probe the compressed mass region
M
1
≲
M
η
±
. Masses of charged scalar
η
±
and dark matter
N
1
can be further extracted by a binned likelihood fit of the dilepton energy.
PDF
