A
bstract
I propose an alternative method for measuring the
CP
violating phase
ϕ
2
(
α
) without ambiguity in an extended SU(2) isospin triangle analysis, which can ultimately be achieved by ...exploiting interference effects between
B
0
→
ρ
0
ρ
0
and
B
0
→
a
1
±
π
∓
in a time-dependent flavour-tagged amplitude analysis. Under certain assumptions on the effective
ϕ
2
in each channel, I demonstrate with an idealised amplitude model that potential deviations in the measured
ϕ
2
due to penguin contamination in
B
0
→
a
1
±
π
∓
are sufficiently large within current experimental uncertainties that this programme could be executed with Run 3 data at LHCb and easily at Belle II.
Abstract
A rescaling of the SU(2) isospin triangles constraining
$$\phi _2$$
ϕ
2
(
$$\alpha$$
α
) that relies on measurements of the experimentally cleaner relative branching fractions, as opposed to ...those absolute, is proposed. Paving the way towards more systematically sustainable analysis, this method promises to eliminate a dominant systematic at Belle II amongst others, namely the uncertainty on the number of
$$B {\bar{B}}$$
B
B
¯
pairs in data. Furthermore, a
$$\phi _2$$
ϕ
2
constraint in the
$$B \rightarrow \rho \rho$$
B
→
ρ
ρ
system at LHCb that is more independent of Belle II input is shown to become viable even without a measurement of
$$C\!P$$
C
P
violation in
$$B^0 \rightarrow \rho ^+\rho ^-$$
B
0
→
ρ
+
ρ
-
.
We report the first observation of the decay Λ_{c}^{+}→pK^{+}π^{-} using a 980 fb^{-1} data sample collected by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. This is the ...first observation of a doubly Cabibbo-suppressed decay of a charmed baryon. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be B(Λ_{c}^{+}→pK^{+}π^{-})/B(Λ_{c}^{+}→pK^{-}π^{+})=(2.35±0.27±0.21)×10^{-3}, where the uncertainties are statistical and systematic, respectively.
Equal amounts of matter and antimatter are predicted to have been produced in the Big Bang, but our observable Universe is clearly matter-dominated. One of the prerequisites for understanding this ...elimination of antimatter is the nonconservation of charge-parity (CP) symmetry. So far, two types of CP violation have been observed in the neutral K meson (K0) and B meson (B0) systems: CP violation involving the mixing between K0 and its antiparticle (and likewise for B0 and ), and direct CP violation in the decay of each meson. The observed effects for both types of CP violation are substantially larger for the B0 meson system. However, they are still consistent with the standard model of particle physics, which has a unique source of CP violation that is known to be too small to account for the matter-dominated Universe. Here we report that the direct CP violation in charged B±→K± 0 decay is different from that in the neutral B0 counterpart. The direct CP-violating decay rate asymmetry, (that is, the difference between the number of observed B-→K- 0 event versus B+→K+ 0 events, normalized to the sum of these events) is measured to be about +7%, with an uncertainty that is reduced by a factor of 1.7 from a previous measurement. However, the asymmetry for versus B0→K+ - is at the -10% level. Although it is susceptible to strong interaction effects that need further clarification, this large deviation in direct CP violation between charged and neutral B meson decays could be an indication of new sources of CP violation-which would help to explain the dominance of matter in the Universe.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
15.
Status of the Belle silicon vertex detector Natkaniec, Z.; Aihara, H.; Asano, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2006, Letnik:
560, Številka:
1
Journal Article
Recenzirano
The old silicon vertex detector (SVD1) of the Belle detector, operating at the high-luminosity asymmetric energy e+e− collider KEKB, was replaced by an upgraded version (SVD2) in 2003. The new ...detector has modified geometry and redesigned readout electronics, providing a larger polar angle acceptance, better vertex resolution, improved radiation hardness and reduced dead time. The operation of the detector started successfully in October 2003. The basic concepts of the SVD2 design as well as its performance after 10 months of data taking are described in this paper.
Abstract I propose an alternative method for measuring the CP violating phase ϕ 2(α) without ambiguity in an extended SU (3) flavour symmetry analysis, which can ultimately be achieved by exploiting ...interference effects between B → AP and B → VV decay channels, where A, V, P indicates an axial-vector, vector and pseudo-scalar meson, respectively. Under certain assumptions on the relevant decays based on current experimental results and minimal theoretical input, I demonstrate with an idealised amplitude model that a programme to extract a single solution for ϕ 2 in the range 0, π, with the added possibility to simultaneously constrain non-factorisable SU(3)-breaking effects, could be executed to similar precision using Run 3 data at LHCb and the final Belle II sample.
We search for bottomonium states in Υ(2S) → (bb)γ decays with an integrated luminosity of 24.7 fb(-1) recorded at the Υ(2S) resonance with the Belle detector at KEK, containing (157.8±3.6)×10(6) ...Υ(2S) events. The (bb) system is reconstructed in 26 exclusive hadronic final states composed of charged pions, kaons, protons, and K(S)(0) mesons. We find no evidence for the state recently observed around 9975 MeV (X(bb)) in an analysis based on a data sample of 9.3×10(6) Υ(2S) events collected with the CLEO III detector. We set a 90% confidence level upper limit on the branching fraction BΥ(2S) → X(bb)γ × ∑(i)BX(bb) → h(i) < 4.9×10(-6), summed over the exclusive hadronic final states employed in our analysis. This result is an order of magnitude smaller than the measurement reported with CLEO data. We also set an upper limit for the ηb(1S) state of BΥ(2S) → ηb(1S)γ × ∑(i)Bηb(1S) → h(i) < 3.7×10(-6).
We report an improved measurement of D0–D‾0 mixing and a search for CP violation in D0 decays to CP-even final states K+K− and π+π−. The measurement is based on the final Belle data sample of 976 ...fb−1. The results are yCP=(1.11±0.22±0.09)% and AΓ=(−0.03±0.20±0.07)%, where the first uncertainty is statistical and the second is systematic.
A narrow pentaquark state, Pc(4312)+, decaying to J/ψp, is discovered with a statistical significance of 7.3σ in a data sample of Λb0→J/ψpK− decays, which is an order of magnitude larger than that ...previously analyzed by the LHCb Collaboration. The Pc(4450)+ pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, Pc(4440)+ and Pc(4457)+, where the statistical significance of this two-peak interpretation is 5.4σ. The proximity of the Σc+D¯0 and Σc+D¯*0 thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.
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