We discuss the eight independent spin observables for the W boson in terms of its vector and tensor polarizations and identify the angular distributions and asymmetries able to separate them in ...collider experiments. The results are applied to the study of polarized top quark decays and diboson resonances. These novel observables are of great value for disentangling new physics mechanisms in W boson production.
We calculate the density matrix for the decay of a polarised top quark into a polarised
W boson and a massive
b quark, for the most general
Wtb vertex arising from dimension-six gauge-invariant ...effective operators. We show that, in addition to the well-known
W helicity fractions, for polarised top decays it is worth defining and studying the transverse and normal
W polarisation fractions, that is, the
W polarisation along two directions orthogonal to its momentum. In particular, a rather simple forward–backward asymmetry in the normal direction is found to be very sensitive to complex phases in one of the
Wtb anomalous couplings. This asymmetry, which indicates a normal
W polarisation, can be generated for example by a P-odd, T-odd transition electric dipole moment. We also investigate the angular distribution of decay products in the top quark rest frame, calculating the spin analysing powers for a general
Wtb vertex. Finally we show that, using a combined fit to top decay observables and the
tW cross section, at LHC it will be possible to obtain model-independent measurements of all the (complex)
Wtb couplings as well as the single top polarisation. Implications for spin correlations in top pair production are also discussed.
We present a novel method to perform a direct T (time reversal) symmetry test in the neutral kaon system, independent of any CP and/or CPT symmetry tests. This is based on the comparison of suitable ...transition probabilities, where the required interchange of in ↔ out states for a given process is obtained exploiting the Einstein–Podolski–Rosen correlations of neutral kaon pairs produced at a ϕ-factory. In the time distribution between the two decays, we compare a reference transition like the one defined by the time-ordered decays (ℓ−,ππ) with the T-conjugated one defined by (3π0,ℓ+). With the use of this and other T-conjugated comparisons, the KLOE-2 experiment at DAΦNE could make a statistically significant test.
One of the most important symmetries in nature is time reversal, namely, that the laws of physics remain dynamically invariant from moving forward to backward in time. Nevertheless, this symmetry can ...be broken in certain physical processes as observed in neutral B mesons by the BABAR Collaboration. Symmetry transformations have been proven a bedrock tool for understanding the nature of particle interactions, formulating, and testing fundamental theories. Based on the up to now unbroken CPT symmetry, the violation of the CP symmetry between matter and antimatter by weak interactions, discovered in the decay of kaons in 1964 and observed more recently in 2001 in mesons, strongly suggests that the behavior of these particles under weak interactions must also be asymmetric under time reversal T. The method allows a clear-cut separation of different transitions between flavor and eigenstates in the decay of neutral mesons. The results, presented in 2012, prove beyond any doubt the violation of time-reversal invariance in the time evolution between these two states of the neutral B meson.
CP-Violation (CPV) was discovered in 1964 in the weak decays of neutral Kaons. This Symmetry Breaking is understood in the Standard Model as a consequence of its Particle Content, codified in the 3×3 ...Cabibbo-Kobayashi-Maskawa Unitary Mixing Matrix. The measured CPV asymmetries for Kaons and B's are well described by this Mechanism, but the current level of experimental accuracy and theoretical uncertainties leaves room for additional sources of CPV, as demanded by Baryogenesis. A direct Time-Reversal-Violation (TRV) Effect was clearly observed in 2012 in the time evolution of neutral B-mesons. The conceptual basis to bypass the irreversibility of decays, and prepare in the B-Factories both the Reference and the T-reverse transitions, is provided by the quantum properties of Entanglement and the Decay as a Filtering Measurement. Flavour and CP eigenstate decay channels allow a separate independent measurement of CP, T and CPT asymmetries. Prospects for extending such a programmeto any pair of B-decays and for Kaonsin DAPHNE are discussed. The interest in measuring CPTV asymmetries in transitions is emphasized. This includes the search for CPT-breaking as well as the case of not having a well-defined CPT operator.
We prove 1 that, in any flavor transition, neutrino oscillation CP violating asymmetries in matter have two disentangled components: (a) a CPT-odd T-invariant term, non-vanishing iff there are ...interactions with matter; (b) a T-odd CPT-invariant term, non-vanishing iff there is genuine CP violation. As function of the baseline, these two terms are distinct L-even and L-odd observables, respectively. In the experimental region of terrestrial accelerator neutrinos, we calculate 2 their approximate expressions from which we prove that, at medium baselines, the CPT-odd component is small and nearly (δ-independent, so it can be subtracted from the experimental CP asymmetry as a theoretical background, provided the hierarchy is known. At long baselines, on the other hand, we find that (i) a Hierarchy-odd term in the CPT-odd component dominates the CP asymmetry for energies above the first oscillation node, and (ii) the CPT-odd term vanishes, independent of the CP phase δ, at E = 0.92 GeV(L/1300 km) near the second oscillation maximum, where the T-odd term is almost maximal and proportional to sin δ. A measurement of the CP asymmetry in these energy regions would thus provide separate information on (i) the neutrino mass ordering, and (ii) direct evidence of genuine CP violation in the lepton sector.
Summary
Vascular malformations classification may pose a diagnostic challenge for physicians. In the early stages, they are diagnosed clinically mainly by visual inspection. For a deeper analysis, ...Doppler ultrasonography is the preferred technique to determine the haemodynamic behaviour of the anomaly. However, this imaging method is not always available and it requires trained operators to acquire and interpret the images. There is a lack of portable and user‐friendly systems that may help physicians in the assessment of vascular malformations. We propose a new diagnostic procedure, more affordable and easier to use, based on a portable thermal camera. This technique provides information about temperature, which has been found to be correlated with the flow rate of the lesion. In our study, > 60 vascular malformations of previously diagnosed patients were analysed with a thermal camera to classify them into low‐flow and high‐flow malformations. The value was 1 for both sensitivity and specificity of this technique.
Summary
Background
Vascular malformations are a complex pathology with few treatment options. In previously published studies, oral sirolimus (rapamycin) has shown promising results in the treatment ...of low‐flow vascular malformations, but its usefulness in high‐flow vascular malformations is controversial.
Aim
To evaluate the efficacy and safety of sirolimus for the treatment of high‐flow vascular malformations in real‐life practice.
Methods
In a unit specializing in vascular anomalies, patients treated with oral sirolimus for high‐flow vascular malformations were located by consulting the drug dispensations. Reviewing the electronic medical records, data on patient demographics, vascular malformation characteristics, treatments, toxicity and clinical course were collected and statistically analysed.
Results
Nine patients with vascular malformations were included: eight had arteriovenous malformation and one had arteriovenous fistula. Six of these malformations were isolated while three were part of a syndrome. Sirolimus was initiated at a dosage of 1–4 mg/day to be taken as a single dose. Partial response was observed in eight of the nine patients (88.9%) with high‐flow vascular malformation, while worsening was observed in the remaining patient. The treatment was well tolerated and at the most recent follow‐up, five patients remained on treatment with oral sirolimus.
Conclusion
Our results show that oral sirolimus is a well‐tolerated therapeutic option, with an excellent safety profile, which can be useful in the long‐term stabilization of patients with high‐flow vascular malformations. Single‐daily dosage may improve long‐term adherence to treatment without worsening its effectiveness.
A
bstract
In this paper we present a novel CPT symmetry test in the neutral kaon system based, for the first time, on the direct comparison of the probabilities of a transition and its CPT reverse. ...The required interchange of
in
↔
out
states for a given process is obtained exploiting the Einstein-Podolsky-Rosen correlations of neutral kaon pairs produced at a
ϕ
-factory. The observable quantities have been constructed by selecting the two semileptonic decays for flavour tag, the
ππ
and 3
π
0
decays for CP tag and the time orderings of the decay pairs. The interpretation in terms of the standard Weisskopf-Wigner approach to this system, directly connects CPT violation in these observables to the violating ℜδ parameter in the mass matrix of
K
0
−
K
¯
0
, a genuine CPT violating effect independent of ΔΓ and not requiring the decay as an essential ingredient.
Possible spurious effects induced by CP violation in the decay and/or a violation of the Δ
S
= Δ
Q
rule have been shown to be well under control. The proposed test is thus fully robust, and might shed light on possible new CPT violating mechanisms, or further improve the precision of the present experimental limits. It could be implemented at the DAΦNE facility in Frascati, where the KLOE-2 experiment might reach a statistical sensitivity of
O
(10
−3
) on the newly proposed observable quantities.
MoEDAL is designed to identify new physics in the form of long-lived highly ionizing particles produced in high-energy LHC collisions. Its arrays of plastic nuclear-track detectors and aluminium ...trapping volumes provide two independent passive detection techniques. We present here the results of a first search for magnetic monopole production in 13 TeV proton-proton collisions using the trapping technique, extending a previous publication with 8 TeV data during LHC Run 1. A total of 222 kg of MoEDAL trapping detector samples was exposed in the forward region and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges exceeding half the Dirac charge are excluded in all samples and limits are placed for the first time on the production of magnetic monopoles in 13 TeV pp collisions. The search probes mass ranges previously inaccessible to collider experiments for up to five times the Dirac charge.
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