At present, there are several hints of lepton flavor non-universality. The LHCb Collaboration has measured RK≡B(B+→K+μ+μ−)/B(B+→K+e+e−), and the BaBar Collaboration has measured ...R(D(⁎))≡B(B¯→D(⁎)+τ−ν¯τ)/B(B¯→D(⁎)+ℓ−ν¯ℓ) (ℓ=e,μ). In all cases, the experimental results differ from the standard model predictions by 2–3σ. Recently, an explanation of the RK puzzle was proposed in which new physics (NP) generates a neutral-current operator involving only third-generation particles. Now, assuming the scale of NP is much larger than the weak scale, this NP operator must be made invariant under the full SU(3)C×SU(2)L×U(1)Y gauge group. In this Letter, we note that, when this is done, a new charged-current operator can appear, and this can explain the R(D(⁎)) puzzle. A more precise measurement of the double ratio R(D)/R(D⁎) can rule out this model.
We present a dark sector model that reproduces the KOTO, MiniBooNE and muon anomalous magnetic moment anomalies. The dark sector is comprised of a light scalar singlet S that has a large coupling to ...a slightly heavier sterile neutrino that mixes with the active neutrinos. The scalar couples to standard model fermions via Yukawa couplings, and to photons via a higher-dimensional coupling. The KOTO signal is a result of the flavor-changing penguin process KL→π0S followed by the decay of S to neutrinos. The sterile neutrino produced in neutrino-nucleus scattering at MiniBooNE decays to an active neutrino and S, which decays electromagnetically and creates an event excess at low energies.
We investigate the implications of the latest LHCb measurement of RK for NP explanations of the B anomalies. The previous data could be explained if the b→sμ+μ− NP is in (I) C9,NPμμ or (II) ...C9,NPμμ=−C10,NPμμ, with scenario (I) providing a better explanation than scenario (II). This continues to hold with the new measurement of RK. However, for both scenarios, this measurement leads to a slight tension of O(1σ) between separate fits to the b→sμ+μ− and RK(⁎) data. In this paper, we investigate whether this tension can be alleviated with the addition of NP in b→se+e−. In particular, we examine the effect of adding such NP to scenarios (I) and (II). We find several scenarios in which this leads to improvements in the fits. Z′ and LQ models with contributions to both b→sμ+μ− and b→se+e− can reproduce the data, but only within scenarios based on (II). If the tension persists in future measurements, it may be necessary to consider NP models with more than one particle contributing to b→sℓ+ℓ−.
A
bstract
Standard Model Neutrino Effective Field Theory (SMNEFT) is an effective theory with Standard Model (SM) gauge-invariant operators constructed only from SM and right-handed neutrino fields. ...For the full set of dimension-six SMNEFT operators, we present the gauge coupling terms of the one-loop anomalous dimension matrix for renormalization group evolution (RGE) of the Wilson coefficients between a new physics scale and the electroweak scale. We find that the SMNEFT operators can be divided into five subsets which are closed under RGE. Our results apply for both Dirac and Majorana neutrinos. We also discuss the operator mixing pattern numerically and comment on some interesting phenomenological implications.
A
bstract
The Standard Model Neutrino Effective Field Theory (SMNEFT) is the Standard Model Effective Field Theory (SMEFT) augmented with right-handed neutrinos. Building on our previous work, ...arXiv:2010.12109, we calculate the Yukawa coupling contributions to the one-loop anomalous dimension matrix for the 11 dimension-six four-fermion SMNEFT operators. We also present the new contributions to the anomalous dimension matrix for the 14 four-fermion SMEFT operators that mix with the SMNEFT operators through the Yukawa couplings of the right-handed neutrinos.
We show that the RK puzzle in LHCb data and the discrepancy in the anomalous magnetic moment of the muon can be simultaneously explained if a 10 MeV mass Z′ boson couples to the muon but not the ...electron, and that clear evidence of the nonstandard matter interactions of neutrinos induced by this coupling may be found at DUNE.
A
bstract
At present, the measurements of
R
D
∗
and
R
J/ψ
hint at new physics (NP) in
b
→
c
τ
−
v
¯
decays. The angular distribution of
B
¯
→
D
∗
→
Dπ
τ
−
v
¯
τ
would be useful for getting ...information about the NP, but it cannot be measured. The reason is that the three-momentum
p
→
τ
cannot be determined precisely since the decay products of the
τ
−
include an undetected
ν
τ
. In this paper, we construct a measurable angular distribution by considering the additional decay
τ
−
→ π
−
ν
τ
. The full process is
B
¯
→
D
∗
→
D
π
′
τ
−
→
π
−
v
τ
v
¯
τ
, which includes three final-state particles whose three-momenta can be measured:
D
,
π
′
,
π
−
. The magnitudes and relative phases of all the NP parameters can be extracted from a fit to this angular distribution. One can measure CP-violating angular asymmetries. If one integrates over some of the five kinematic parameters parametrizing the angular distribution, one obtains (i) familiar observables such as the
q
2
distribution and the
D
∗
polarization, and (ii) new observables associated with the
π
−
emitted in the
τ
decay: the forward-backward asymmetry of the
π
−
and the CP-violating triple-product asymmetry.
Hint of a new scalar interaction in LHCb data? Datta, Alakabha; Marfatia, Danny; Mukherjee, Lopamudra
European physical journal. C, Particles and fields,
06/2024, Letnik:
84, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We explain recent LHCb measurements of the lepton universality ratios,
R
D
(
∗
)
τ
/
ℓ
≡
B
(
B
¯
→
D
(
∗
)
+
τ
-
ν
¯
τ
)
B
(
B
¯
→
D
(
∗
)
+
ℓ
-
ν
¯
ℓ
)
and
R
(
Λ
c
+
)
τ
/
ℓ
≡
B
(
Λ
b
→
Λ
c
+
τ
-
ν
...¯
τ
)
B
(
Λ
b
→
Λ
c
+
ℓ
-
ν
¯
ℓ
)
with
ℓ
=
μ
, via new physics that affects
R
D
τ
/
ℓ
and
R
(
Λ
c
+
)
τ
/
ℓ
but not
R
D
∗
τ
/
ℓ
. The scalar operator in the effective theory for new physics is indicated. We find that the forward-backward asymmetry and
τ
polarization in
B
¯
→
D
+
τ
-
ν
¯
τ
and
Λ
b
→
Λ
c
+
τ
-
ν
¯
τ
decays are significantly affected by the scalar interaction. We construct a simple two Higgs doublet model as a realization of our scenario and consider lepton universality in semileptonic charm and top decays, radiative
B
decay,
B
-mixing, and
Z
→
b
b
¯
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
10.
Flavor SU(3) in Cabibbo-favored D-meson decays Bhattacharya, Bhubanjyoti; Datta, Alakabha; Petrov, Alexey A. ...
The journal of high energy physics,
10/2021, Letnik:
2021, Številka:
10
Journal Article
Recenzirano
Odprti dostop
A
bstract
Model-independent description of nonleptonic decays of charmed mesons is a challenging task due to large nonperturbative effects of strong interactions on the transition amplitudes. We ...discuss the equivalence of two different flavor-SU(3)-based descriptions of Cabibbo-favored non-leptonic decays of charmed mesons to two-pseudoscalars final states including the
η
and
η
′ mesons.
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