A measurement of the photon polarization in radiative penguin
B
decays provides a test of the Standard Model and a probe for New Physics, that can lead to a deviation from the Standard Model ...prediction of left-handed photons in
b
→
s
γ
. We propose a new method to measure the photon polarization using the baryonic decay
B
-
→
Λ
p
¯
γ
. The
P
-violating
Λ
-hyperon decay allows a measurement of the
Λ
helicity to be performed, which can be uniquely related to the photon polarization in a model-independent way. The
B
-
→
Λ
p
¯
γ
decay was recently measured to have a large branching fraction providing a possibility to get meaningful results with the data already available at LHC and B-factory experiments. An increase of the
B
-meson sample at high luminosity LHC experiments and Belle II should provide a really stringent test by using this method already in the near future.
Abstract Nowadays High Energy Physics experiments can accumulate unprecedented statistics of heavy flavour decays that allows to apply new methods, based on the study of very rare phenomena, which ...used to be just desperate. In this paper we propose a new method to measure composition of K 0- K ¯ $$ \overline{K} $$ 0, produced in a decay of heavy hadrons. This composition contains important information, in particular about weak and strong phases between amplitudes of the produced K 0 and K ¯ $$ \overline{K} $$ 0. We consider possibility to measure these parameters with time-dependent K 0 → π + π − analysis. Due to C P -violation in kaon mixing time-dependent decay rates of K 0 and K ¯ $$ \overline{K} $$ 0 differ, and the initial amplitudes revealed in the CP-violating decay pattern. We perform phenomenological study of K 0 decay evolution initially produced as a combination a K 0 t + b K ¯ 0 t $$ a\left.|{K}^0(t)\right\rangle +b\left.|{\overline{K}}^0(t)\right\rangle $$ , where a and b, complex amplitudes, could also be dependent on decay time of heavy mother particle. In particular we consider cases of charmed hadrons decays: D + → K 0 π +, D s + $$ {D}_s^{+} $$ → K 0 K +, Λ → pK 0 and with some assumptions D 0 → K 0 π 0. This can be used to test the sum rule for charmed mesons and to obtain input for the full constraint of the two body amplitudes of D-mesons.
A
bstract
Nowadays High Energy Physics experiments can accumulate unprecedented statistics of heavy flavour decays that allows to apply new methods, based on the study of very rare phenomena, which ...used to be just desperate. In this paper we propose a new method to measure composition of
K
0
-
K
¯
0
, produced in a decay of heavy hadrons. This composition contains important information, in particular about weak and strong phases between amplitudes of the produced
K
0
and
K
¯
0
. We consider possibility to measure these parameters with time-dependent
K
0
→
π
+
π
−
analysis. Due to
C P
-violation in kaon mixing time-dependent decay rates of
K
0
and
K
¯
0
differ, and the initial amplitudes revealed in the
CP
-violating decay pattern. We perform phenomenological study of
K
0
decay evolution initially produced as a combination
a
K
0
t
+
b
K
¯
0
t
, where
a
and
b
, complex amplitudes, could also be dependent on decay time of heavy mother particle. In particular we consider cases of charmed hadrons decays:
D
+
→
K
0
π
+
,
D
s
+
→
K
0
K
+
, Λ →
pK
0
and with some assumptions
D
0
→
K
0
π
0
. This can be used to test the sum rule for charmed mesons and to obtain input for the full constraint of the two body amplitudes of
D
-mesons.
In a previous paper we suggested an explanation for the peak designated as Z(4430)+ in the ψ′π+ mass spectrum, observed by Belle in B¯→ψ′π+K decays, as an effect of D¯⁎0D+→ψ′π+ rescattering in the ...decays B¯→Ds′−D, where the Ds′− is an as-yet unobserved radial excitation of the pseudoscalar ground state Ds−-meson. In this paper, we demonstrate that this hypothesis provides an explanation of the double Z+-like peaking structures, which were studied by LHCb with much higher statistics. While according to our hypothesis, the origin of the peaking structures is due to the kinematical reflection of conventional resonances in the unobserved intermediate state, the amplitude of the Z(4430)+ peak carries a Breit–Wigner-like complex phase, arising from the intermediate Ds′− resonance. Thus, our hypothesis is entirely consistent with the recent LHCb measurement of the resonant-like amplitude behavior of the Z(4430)+. We perform a toy fit to the LHCb data, which illustrates that our approach is also consistent with all the observed structure in the LHCb M(ψ′π+) spectrum. We suggest a critical test of our hypothesis that can be performed experimentally.
A
bstract
This paper provides a detailed description of the method for the first direct measurement of all Michel parameters in the
τ
−
→ μ
−
ν
¯
μ
ν
τ
decay related to the polarization of the ...daughter muon. An application of the suggested method in the existing and future experiments at
e
+
e
−
colliders is considered. We have performed a feasibility study for the future Super Charm-Tau Factory and Belle II experiments. For the first one, the sensitivity to the Michel parameters
ξ
′,
ξ
′′,
η
′′,
α
′
/A
, and
β
′
/A
is estimated. For the latter, only one Michel parameter,
ξ
′, for which the sensitivity is maximum, is considered.
A method for measuring all Michel parameters describing the daughter muon polarization in the
decay, i.e.,
,
,
,
, and
, is discussed. The application of the method to the future Super Charm-Tau ...Factory experiment is considered. The statistical uncertainties expected by the full data statistics (10 ab
–1
) are estimated as
,
,
,
, and
. On their basis, upper limits on the coupling constants of interactions beyond the Standard Model are estimated. The New Physics scenario is considered, which can be reliably detected if the estimated accuracy of the
parameter measurement is achieved.
A
bstract
We propose a new method to extract
D
0
−
D
¯
0
mixing parameters using the
D
0
→
K
¯
0
π
0
decay with the
K
¯
0
reconstructed in the semileptonic mode. Although a
K
0
→
π
±
ℓ
∓
v
ℓ
decay ...suffers from low statistics and complexity of the secondary vertex reconstruction in comparison to the standard
K
S
0
→
π
+
π
−
vertex, it provides much richer, sometimes unique information about the initial state of a
K
0
-meson produced in a heavy-flavor hadron decay. In this paper it is shown that the reconstruction of the chain
D
0
→
K
0
(
π
±
ℓ
∓
v
ℓ
)
π
0
allows one to extract the strong phase difference between the doubly Cabibbo-suppressed and Cabibbo-favored decay amplitudes, which is of key importance for determination of the
D
0
−
D
¯
0
-mixing parameters.
A
bstract
This paper provides a detailed description of the method for the first direct measurement of all Michel parameters in the
τ
−
→ μ
−
$$ \overline{\nu} $$
ν
¯
μ
ν
τ
decay related to the ...polarization of the daughter muon. An application of the suggested method in the existing and future experiments at
e
+
e
−
colliders is considered. We have performed a feasibility study for the future Super Charm-Tau Factory and Belle II experiments. For the first one, the sensitivity to the Michel parameters
ξ
′,
ξ
′′,
η
′′,
α
′
/A
, and
β
′
/A
is estimated. For the latter, only one Michel parameter,
ξ
′, for which the sensitivity is maximum, is considered.
We review numerous results from the B-Factories, obtained last decade. They provide currently strong constraints on New Physics extensions beyond the Standard Model. We discuss the physics program at ...Super B-factory, a next generation asymmetric collider with the luminosity almost two orders of magnitude higher than those achieved at the existing colliders, and its capability in cooperation with LHC of new insights into New Physics phenomena.
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