Investigation at a
φ
-factory can shed light on several debated issues in particle physics. We discuss: (i) recent theoretical development and experimental progress in kaon physics relevant for the ...Standard Model tests in the flavor sector, (ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled-kaon states, (iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and
η
/
η
′ mesons, (iv) the contribution to understand the nature of light scalar mesons, and (v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the
e
+
e
−
physics in the continuum with the measurements of (multi)hadronic cross sections and the study of
γ
γ
processes.
The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for the ...light vector mediator of this dark force, the U boson, with the KLOE detector at the DAΦNE e+e− collider. Using an integrated luminosity of 1.54 fb−1, we studied the process e+e−→Uγ, with U→e+e−, using radiative return to search for a resonant peak in the dielectron invariant-mass distribution. We did not find evidence for a signal, and set a 90% CL upper limit on the mixing strength between the Standard Model photon and the dark photon, ε2, at 10−6–10−4 in the 5–520 MeV/c2 mass range.
The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in ...e+e−→Uγ, U→π+π− based on 28 million e+e−→π+π−γ events collected at DAΦNE by the KLOE experiment. The π+π− production by initial-state radiation compensates for a loss of sensitivity of previous KLOE U→e+e−, μ+μ− searches due to the small branching ratios in the ρ–ω resonance region. We found no evidence for a signal and set a limit at 90% CL on the mixing strength between the photon and the dark photon, ε2, in the U mass range between 527 and 987MeV. Above 700 MeV this new limit is more stringent than previous ones.
We present a search for the lepton flavor violating decays B^{+}→K^{+}τ^{±}ℓ^{∓}, with ℓ=(e,μ), using the full data sample of 772×10^{6} BBover ¯ pairs recorded by the Belle detector at the KEKB ...asymmetric-energy e^{+}e^{-} collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B^{±}→K^{±}τℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1-3)×10^{-5} range. The obtained limits are the world's best results.
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A
bstract
The quantum interference between the decays of entangled neutral kaons is studied in the process
ϕ
→ K
S
K
L
→
π
+
π
−
π
+
π
−
, which exhibits the characteristic Einstein-Podolsky-Rosen ...correlations that prevent both kaons to decay into
π
+
π
−
at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon pair state, and to search for tiny decoherence and
CPT
violation effects, which may be justified in a quantum gravity framework.
The analysed data sample was collected with the KLOE detector at DAΦNE, the Frascati
ϕ
-factory, and corresponds to an integrated luminosity of about 1.7 fb
−
1
, i.e. to about 1
.
7 × 10
9
ϕ
→ K
S
K
L
decays produced. From the fit of the observed ∆
t
distribution, being ∆
t
the difference of the kaon decay times, the decoherence and
CPT
violation parameters of various phenomenological models are measured with a largely improved accuracy with respect to previous analyses.
The results are consistent with no deviation from quantum mechanics and
CPT
symmetry, while for some parameters the precision reaches the interesting level at which — in the most optimistic scenarios — quantum gravity effects might show up. They provide the most stringent limits up to date on the considered models.
We describe the assembly procedure and the performance tests of 62 high pressure drift tube chambers, MDT, that equip the inner ring of the Muon Barrel Spectrometer of the ATLAS experiment at the ...LHC. The uniformity of response of the drift tubes and the tracking performance of the chambers were measured with cosmic rays and compared with the results obtained with high momentum muons.
Background : Deep venous thrombosis (DVP) is a frequent disease. Prophylaxis is the best means to reduce its incidence, for lowering morbidity and mortality rates and treatment costs caused by its ...complications. Objective : To evaluate the knowledge and use of any kind of DVT prophylaxis by Brazilian Oral and Maxillofacial surgeons. Materials and Methods : A questionnaire was sent to all Oral and Maxillofacial surgeons associated to the Brazilian College of Oral and Maxillofacial Surgeons that have a valid e-mail address. The data retrieved was evaluated and tabulated. Results : Of the 1100 questionnaires sent, only 4% were retrieved. The 42 retrieved were included in the study. Twenty six of the surgeons do not use any kind of deep venous thrombosis (DVT) prophylaxis, 11 use mechanical means as elastic compressive stockings or pneumatic compressive devices for prophylaxis, and 5 uses low-molecular weight heparins (LMWH) as the choice for prophylaxis. Conclusion : The data collected, despite the low rate of participation (4%) by the surgeons, shows that this subject still does not receive proper attention. Whereas other medical specialties make routine use of prophylactic means maybe the maxillofacial surgeons lack concern on that matter.
Measurement of the K-S ? Babusci, D.; Berlowski, M.; Bloise, C. ...
The journal of high energy physics,
02/2023
2
Journal Article
Peer reviewed
Open access
The ratio R = gamma(K-S -> pi e nu)/gamma(KS -> pi(+)pi(-)) has been measured with a sample of 300 million KS mesons produced in phi -KLKS decays recorded by the KLOE experiment at the DA Phi ...NE e(+)e(-) collider. K-S -> pi e nu events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of K-L -> pi e nu decays are used to evaluate signal selection efficiencies. With 49647 +/- 316 signal events we measure R = (1.0421 +/- 0.0066(stat) +/- 0.0075(syst)) x 10(-3). The combination with our previous measurement gives R = (1.0338 +/- 0.0054(stat) +/- 0.0064(syst)) x 10(-3). From this value we derive the branching fraction B(K-S -> pi e nu) = (7.153 +/- 0.037(stat)+/- 0.044(syst)) x 10(-4) and f(+)(0)|V-us| = 0.2170 +/- 0.009.
We searched for the μ+μ− decay of a light vector gauge boson, also known as dark photon, in the e+e−→μ+μ−γISR process by means of the Initial State Radiation (ISR) method. We used 1.93 fb−1 of data ...collected by the KLOE experiment at the DAΦNE ϕ-factory. No structures have been observed over the irreducible μ+μ− background. A 90% CL limit on the ratio ε2=α′/α between the dark coupling constant and the fine structure constant of 3×10−6–2×10−7 has been set in the dark photon mass region between 519 MeV and 973 MeV. This new limit has been combined with the published result obtained investigating the hypothesis of the dark photon decaying into hadrons in e+e−→π+π−γISR events. The combined 90% CL limit increases the sensitivity especially in the ρ–ω interference region and excludes ε2 greater than (13−2)×10−7. For dark photon masses greater than 600 MeV the combined limit is lower than 8 ×10−7 resulting more stringent than present constraints from other experiments.
We report on a search for a heavy Majorana neutrino in the decays τ^{-}→π^{-}ν_{h}, ν_{h}→π^{±}ℓ^{∓}, ℓ=e, μ. The results are obtained using the full data sample of 988 fb^{-1} collected with the ...Belle detector at the KEKB asymmetric energy e^{+}e^{-} collider, which contains 912×10^{6} ττ pairs. We observe no significant signal and set 95% CL upper limits on the couplings of the heavy right-handed neutrinos to the conventional standard model left-handed neutrinos in the mass range 0.2-1.6 GeV/c^{2}. This is the first study of a mixed couplings of heavy neutrinos to τ leptons and light-flavor leptons.
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