Lepton-flavor violating axions at MEG II Jho, Yongsoo; Knapen, Simon; Redigolo, Diego
The journal of high energy physics,
10/2022, Volume:
2022, Issue:
10
Journal Article
Peer reviewed
Open access
A
bstract
We study the sensitivity of the existing MEG data to lepton flavor violating axion-like particles produced through
μ
+
→
e
+
aγ
and estimate the discovery potential for the upcoming MEG II ...experiment in this channel. The MEG II signal efficiency can be improved significantly if a new trigger can be implemented in a dedicated run with a reduced beam intensity. This search would establish the world leading measurement in this channel with only 1 month of data taking.
The recently reported excess in XENON1T is explained by new leptonic forces, which are free from gauge anomalies. We focus on two scenarios with and without dark matter. In Scenario #1, the gauge ...boson of gauged lepton number U(1)Le−Lj, j=μ or τ provides non-standard interaction between solar neutrino and electron that enhances the number of electron recoil events in the XENON1T detector. In Scenarino #2, the new gauge boson exclusively couples to electron and dark matter, then cosmic-ray electrons can transfer their momenta to dark matter in halo. The boosted dark matter generates the electron recoil signals of O(1) keV. The dark matter, aided by the new gauge interaction, efficiently heats up a neutron star in our Galaxy more than ∼1500 K as a neutron star captures the halo dark matter. Therefore, we propose to utilize the future infrared telescope to test our scenario.
A
bstract
Motivated by the long-lasting 3
.
5
σ
discrepancy in the anomalous magnetic moment of muon, we consider a new muon-specific force mediated by a light gauge boson,
X
, with mass
m
X
< 2
m
μ
...and the coupling constant
gX
∼ (10
−4
, 10
−3
) . We show that the Belle II experiment has a robust chance to probe such a light boson in
e
+
e
−
→
μ
+
μ
−
+
X
channel and cover the most interesting parameter space explaining the discrepancy with the planned target luminosity,
∫
dt
L
=
50
ab
−
1
. The clean signal of muon-pair plus missing energy at Belle II can be a smoking gun for the new gauge boson. We expect that the (invisibly decaying) muon-philic light (
m
X
≲ 2
m
μ
) gauge boson can be probed down to
g
X
≲ 1.5 × 10
−4
(4.6 × 10
−4
, 2.3 × 10
−4
) for 50 (1, 10) ab
−1
search.
A
bstract
We investigate various search strategies for light vector boson
X
in
O
(10) MeV mass range using
J/
Ψ associated channels at BESIII and Belle II:
(i) J/
Ψ →
η
c
X
with 10
10
J/
Ψs at ...BESIII,
(ii) J/
Ψ(
η
c
+
X
) +
ℓ
ℓ
¯
production at Belle II, and
(iii) J/
Ψ +
X
with the displaced vertex in
X
→
e
+
e
−
decay are analyzed and the future sensitivities at Belle II with 50 ab
−
1
luminosity are comprehensively studied. By requiring the displaced vertex to be within the beam pipe, the third method results in nearly background-free analysis, and the vector boson-electron coupling and the vector boson mass can be probed in the unprecedented range, 10
−
4
≤ |
ε
e
| ≤ 10
−
3
and 9 MeV ≤
m
X
≤ 100MeV with 50 ab
−
1
at Belle II. This covers the favored signal region of
8
Be
*
anomaly recently reported by Atomki experiment with
m
X
≃ 17 MeV.
A
bstract
We discuss a list of possible light gauge boson interpretations for the long- standing experimental anomaly in (
g −
2)
μ
and also recent anomalous excess in
K
L
→ π
0
+ (invisible) events ...at the J-PARC KOTO experiment. We consider two models:
i) L
μ
− L
τ
gauge boson with heavy vector-like quarks and
ii)
(
L
μ
− L
τ
) +
є
(
B
3
− L
τ
) gauge boson in the presence of right-handed neutrinos. When the light gauge boson has mass close to the neutral pion in order to satisfy the Grossman-Nir bound, the models successfully explain the anomalies simultaneously while satisfying all known experimental constraints. We extensively provide the future prospect of suggested models.
Semiclassical processes such as production and decay of electroweak sphaleron in the Standard Model and also microscopic black hole in low scale gravity scenario typically involve large number of ...particles in final states. These large multiplicities can be distinctively seen in collisions of ultra-high-energy (UHE) neutrinos with Eν ≳ 109 GeV and nucleons in the atmosphere of the Earth. Focusing on air-shower detector array experiments including Telescope Array Experiment (TA), Pierre-Auger Observatory (Auger), we propose strategic ways to discover and analyze such events.
Abstract
Recently reported anomalies in various B-meson decays and also in the anomalous magnetic moment of muon (g − 2)μ motivate us to consider a particular extension of the standard model ...incorporating new interactions in the lepton and quark sectors simultaneously. Our minimal choice would be the leptoquark. In particular, we take the vector leptoquark (U1) and comprehensively study all related observables including ${(g-2)_{\mu }},\ R_{K^{(*)}},\ R_{D^{(*)}}$, B → (K)ℓℓ′, where ℓℓ′ are various combinations of μ and τ, and also lepton flavor violation in the τ decays. We find that a hybrid scenario with an additional $U(1)_{B_3-L_2}$ gauge boson provides a common explanation for all these anomalies.
Abstract We discuss a list of possible light gauge boson interpretations for the long- standing experimental anomaly in (g − 2) μ and also recent anomalous excess in K L → π 0 + (invisible) events at ...the J-PARC KOTO experiment. We consider two models: i) L μ − L τ gauge boson with heavy vector-like quarks and ii) (L μ − L τ ) + є(B 3 − L τ ) gauge boson in the presence of right-handed neutrinos. When the light gauge boson has mass close to the neutral pion in order to satisfy the Grossman-Nir bound, the models successfully explain the anomalies simultaneously while satisfying all known experimental constraints. We extensively provide the future prospect of suggested models.
We study the sensitivity of the existing MEG data to lepton flavor violating axion-like particles produced through \(\mu^+ \to e^+ a \gamma\) and estimate the discovery potential for the upcoming MEG ...II experiment in this channel. The MEG II signal efficiency can be improved significantly if a new trigger can be implemented in a dedicated run with a reduced beam intensity. This search would establish the world leading measurement in this channel with only 1 month of data taking.
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