Recently CDF II Collaboration reported that they measured W boson mass precisely. The measurement is deviated from the Standard Model (SM) Prediction at 7σ. Also, the recent FNAL measurement of the ...muon magnetic moment shows a 4.2σ deviation. To resolve the W boson as well as the muon (g−2) anomalies, we explore the type-X two Higgs doublet model (2HDM). We analyze the (mA,tanβ) parameter space of the type-X 2HDM consistent with the muon (g−2), lepton universality test and recent W boson mass measurements from the CDF II collaboration. We find that the measurement of the h→AA branching ratio gives a strong lower mass bound on mH.
Recently XENON1T Collaboration announced that they observed some excess in the electron recoil energy around a 2–3 keV. We show that this excess can be interpreted as exothermic scattering of excited ...dark matter on atomic electron through dark photon exchange. We consider DM models with local dark U(1) gauge symmetry that is spontaneously broken into its Z2 subgroup by Krauss-Wilczek mechanism. In order to explain the XENON1T excess with the correct DM thermal relic density within freeze-out scenario, all the particles in the dark sector should be light enough, namely ∼O(100) MeV for scalar DM and ∼O(1−10) MeV for fermion DM cases. And even lighter dark Higgs ϕ plays an important role in the DM relic density calculation: XX†→Z′ϕ for scalar DM (X) and χχ¯→ϕϕ for fermion DM (χ) assuming mZ′>mχ. Both of them are in the p-wave annihilation, and one can easily evade stringent bounds from Planck data on CMB on the s-wave annihilations, assuming other dangerous s-wave annihilations are kinematically forbidden.
A
bstract
The CP violating two-Higgs doublet model of type-X may enhance significantly the electric and magnetic moment of leptons through two-loop Barr-Zee diagrams. We analyze the general parameter ...space of the type-X 2HDM consistent with the muon
g −
2 and the electron EDM measurements to show how strongly the CP violating parameter is constrained in the region explaining the muon
g −
2 anomaly.
In this study, silicon (Si) was doped on a tetrahedral amorphous carbon (ta-C) coating and the tribological characteristics of the resulting Si-doped diamond-like carbon (DLC; a-C:Si:H) were ...investigated against a SUJ2 ball. The Si fraction in the coating was varied from 0 to ~ 20 at.% by increasing the trimethylsilane gas flow rate during filtered cathodic vacuum arc deposition. The coefficient of friction (CoF) showed no obvious change when the Si fraction was less than ~ 7 at.%. However, after Si doping, it significantly decreased when the Si fraction was greater than ~ 8 at.%. The running-in period also decreased to less than 1000 cycles after Si doping. The rapid formation of Si-rich debris and transfer layer led to the fabrication of a low-friction tribofilm, which was induced by the tribochemical reaction with moisture under ambient conditions. When the Si fraction was ~ 17 at.%, the lowest CoF of less than 0.05 was obtained. Further Si doping beyond the critical point led to the destruction of the film because of reduced hardness.
Searching for flavored gauge bosons Chun, Eung Jin; Das, Arindam; Kim, Jinsu ...
The journal of high energy physics,
02/2019, Letnik:
2019, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
Standard Model may allow an extended gauge sector with anomaly-free flavored gauge symmetries, such as
L
i
−
L
j
,
B
i
−
L
j
, and
B
−3
L
i
, where
i, j
= 1
,
2
,
3 are flavor indices. We ...investigate phenomenological implications of the new flavored gauge boson
Z
′
in the above three classes of gauge symmetries. Focusing on the gauge boson mass above 5 GeV, we use the lepton universality test in the
Z
and
τ /μ
decays, LEP searches, LHC searches, neutrino trident production bound, and LHC
Z
→ 4
μ
searches to put constraints on the
g
′
−
M
Z
′ plane. When
L
1
is involved, the LEP bounds on the
e
−
e
+
→
ℓ
−
ℓ
+
processes give the most stringent bounds, while the LHC bound becomes the strongest constraints in the large
M
Z
′
region when
B
i
is involved. The bound from
Z
→ 4
μ
productions, which is applicable for
L
2
-involved scenarios, provides stringent bounds in the small
M
Z
′
region. One exception is the
B
− 3
L
2
scenario, in which case only a small region is favored due to the lepton universality.
We explore muon anomalous magnetic moment (muon g−2) in a scotogenic neutrino model with a gauged lepton number symmetry U(1)μ−τ. In this model, a dominant muon g−2 contribution comes not from an ...additional gauge sector but from a Yukawa sector. In our numerical Δχ2 analysis, we show that our model is in favor of normal hierarchy with some features. We demonstrate one benchmark point, satisfying muon g−2 at the best fit value 25.1×10−10.
We propose an attractive model that excess of electron recoil events around 1-5 keV reported by the XENON1T collaboration nicely links to the tiny neutrino masses based on a radiative seesaw ...scenario. Our dark matter (DM) is an isospin singlet inert boson that plays an role in generating non-vanishing neutrino mass at one-loop level, and this DM inelastically interacts with a pair of electrons at one-loop level that is required to explain the XENON1T anomaly. It is also demanded that the mass difference between an excited DM and DM has to be of the order keV. Interestingly, the small mass difference ∼keV is proportional to the neutrino masses. It suggests that we have double suppressions through the tiny mass difference and the one-loop effect. Then, we show some benchmark points to explain the XENON1T anomaly, satisfying all the constraints such as the event ratio of electrons of XENON1T, a long lived particle be longer than the age of Universe, and relic density in addition to the neutrino oscillation data and lepton flavor violations (LFVs).
Abstract It is clear that matter is dominant in the Universe compared to antimatter. We call this problem baryon asymmetry. The baryon asymmetry is experimentally determined by both cosmic microwave ...background and big bang nucleosynthesis measurements. To resolve the baryon number asymmetry of the Universe as well as neutrino oscillations, we study a radiative seesaw model in a modular A 4 symmetry. Degenerate heavy Majorana neutrino masses can be naturally realized in an appropriate assignments under modular A 4 with large imaginary part of modulus τ, and it can induce measured baryon number via resonant leptogenesis that is valid in around TeV scale energy theory. We also find that the dominant contribution to the CP asymmetry arises from Reτ through our numerical analysis satisfying the neutrino oscillation data.
We report the structure, mechanical properties, thermal stability, and durability of Si/SiC/ta-C composite (Si-ta-C) coatings fabricated using simultaneous filtered cathodic vacuum arc deposition and ...direct current unbalanced magnetron sputtering. Si concentration of 1.25-6.04 at.% was achieved by increasing the unbalanced magnetron sputtering power from 25 to 175 W. Si addition provided functionality to the coating, such as heat resistance, while retaining the high hardness of ta-C coatings. The Si-ta-C coatings were stable up to 600 °C regardless of the Si content, while the coating containing 3.85 at.% Si was stable up to 700 °C. The friction behavior and mechanical properties were dependent on the coating film before and after annealing at 100-200 °C; however, annealing at 300-400 °C decreased disk wear and increased counterpart wear due to an increase in film hardness on account of an endothermic reaction that increased the number of Si-C bonds. This indicates that the basic hardness characteristics of the ta-C coating and the high-temperature structural change of the Si-ta-C coating are important for ensuring high-temperature durability. These characteristics were verified through the low coefficient of friction and wear rate of the 1.25 at.% Si-ta-C coating after annealing at 500 °C.
A
bstract
It is clear that matter is dominant in the Universe compared to antimatter. We call this problem baryon asymmetry. The baryon asymmetry is experimentally determined by both cosmic microwave ...background and big bang nucleosynthesis measurements. To resolve the baryon number asymmetry of the Universe as well as neutrino oscillations, we study a radiative seesaw model in a modular
A
4
symmetry. Degenerate heavy Majorana neutrino masses can be naturally realized in an appropriate assignments under modular
A
4
with large imaginary part of modulus
τ
, and it can induce measured baryon number via resonant leptogenesis that is valid in around TeV scale energy theory. We also find that the dominant contribution to the CP asymmetry arises from Re
τ
through our numerical analysis satisfying the neutrino oscillation data.
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