A
bstract
It is well known that in
b
-hadron decays with a single unreconstructible final state particle, the decay kinematics can be solved up to a quadratic ambiguity, without any knowledge of the
...b
-hadron momentum. We present a method to infer the momenta of
b
-hadrons produced in hadron collider experiments using information from their reconstructed flight vectors. Our method is strictly agnostic to the decay itself, which implies that it can be validated with control samples of topologically similar decays to fully reconstructible final states. A multivariate regression algorithm based on the flight information provides a
b
-hadron momentum estimate with a resolution of around 60% which is sufficient to select the correct solution to the quadratic equation in around 70% of cases. This will improve the ability of hadron collider experiments to make differential decay rate measurements with semileptonic
b
-hadron decays.
c-VEMPs and o-VEMPs are a new diagnostic tool to detect diseases of the inner ear and the vestibular pathways. The aim of our study was to assess the reliability of c-VEMPs and o-VEMPs in some ...otoneurological diseases. We examined 27 patients, 15 F, 12 M, mean age 42,5. 20 Ménière disease (MD), 3 Benign Paroxysmal Positional Vertigo (BPPV) and 4 vestibular neuritis (VN). c-VEMPs were recorded from electrodes placed over the SCM, with reference over the clavicle. o-VEMPs from the same electrodes placed beneath the eye and reference 2 cm below. For both c-VEMPs and o-VEMPs we used acoustic stimuli (tone burst, 117 dB SPL). MD: both c-VEMPs and o-VEMPs were normal in 13 patients (65%); c-VEMPs were abnormal in 1 patient (5%); o-VEMPs in 4 patients (20%) and both c-VEMPs and o-VEMPs in 2 patients (10%). BPPV: normal in 2 pts. (67%); o-VEMPs abnormal in 1 pt. (33%) VN: c-VEMPs abnormal in 1 pt; (25%), o-VEMPs in 1pt. (25%) both c-VEMPs and o-VEMPs in 2 pts. (50%). c-VEMPs and o-VEMPs seem to be reliable tests to improve the diagnosis of otoneurological diseases. We point out that in some subjects with MD the only abnormal test was o-VEMPs.
Vestibular neuritis (VN) is a common neuro-otologic syndrome characterized by acute prolonged vertigo lasting several days, nausea, vomiting. Vestibular-evoked myogenic potentials (VEMPs) are ...becoming the better diagnostic tool in this pathology. VEMPs can be recorded from tonically contracted neck muscles by acoustic and galvanic stimulation or forehead tap (cervical VEMPs, c-VEMPs) or from extraocular muscles, using the same stimuli. (ocular VEMPs, o-VEMPs). The aim of our study was to assess the reliability of c-VEMPs and o-VEMPs in the diagnosis of VN. We examined 16 patients, 6 F, 10M, mean age 50.1 with vestibular neuritis (VN). c-VEMPs were recorded from electrodes placed over the SCM, with reference placed over the clavicle. o-VEMPs were recorded from the same electrodes placed beneath the eye and reference 2cm below. For both c-VEMPs and o-VEMPs we used acoustic stimuli. In 10 patients (62.5%), only o-VEMPs were absent or abnormal in the affected side; in one patient (6.2%) only c-VEMPs were abnormal; in 5 patients (31.2%) both c-VEMPs and o-VEMPs were absent or abnormal. c-VEMPs and o-VEMPs are reliable tests in the diagnosis of VN. Our results confirm o-VEMPs to be the most impaired test in this disease.
It is well known that in \(b\) hadron decays with a single unreconstructible final state particle, the decay kinematics can be solved up to a quadratic ambiguity, without any knowledge of the \(b\) ...hadron momentum. We present a method to infer the momenta of \(b\) hadrons produced in hadron collider experiments using information from their reconstructed flight vectors. Our method is strictly agnostic to the decay itself, which implies that it can be validated with control samples of topologically similar decays to fully reconstructible final states. A multivariate regression algorithm based on the flight information provides a \(b\) hadron momentum estimate with a resolution of around 60% which is sufficient to select the correct solution to the quadratic equation in around 70% of cases. This will improve the ability of hadron collider experiments to make differential decay rate measurements with semileptonic \(b\) hadron decays.
The performance of the ring-imaging Cherenkov detectors at the LHCb experiment is determined during the LHC Run 2 period between 2015 and 2018. The stability of the Cherenkov angle resolution and ...number of detected photons with time and running conditions is measured. The particle identification performance is evaluated with data and found to satisfy the requirements of the physics programme.
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