scholarly journals Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
P. Moskal ◽  
A. Gajos ◽  
M. Mohammed ◽  
J. Chhokar ◽  
N. Chug ◽  
...  
Keyword(s):  
Tomographic Reconstruction ◽  
Bound State ◽  
Cpt Symmetry ◽  
Final State ◽  
Positron Emission Tomography Scanner ◽  
Correlation Operator ◽  
Angular Correlations ◽  
Fundamental Symmetry ◽  
Positron Emission ◽  
Charge Parity

AbstractCharged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron–positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation operator sensitive to CPT-violating effects. We find no violation at the precision level of 10−4, with an over threefold improvement on the previous measurement.

scholarly journals Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

2021 ◽  
Author(s):  
Pawel Moskal ◽  
Aleksander Gajos ◽  
Muhsin Mohammed ◽  
Jyoti Chhokar ◽  
Neha Chug ◽  
...  
Keyword(s):  
Angular Correlation ◽  
Imaging Techniques ◽  
Tomographic Reconstruction ◽  
Bound State ◽  
Cpt Symmetry ◽  
Final State ◽  
Positron Emission Tomography Scanner ◽  
Fundamental Symmetry ◽  
Positron Emission ◽  
Charge Parity

Abstract Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron–positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner as a high-acceptance photon detector to study CPT-prohibited angular correlation in ortho-positronium (o-Ps) annihilations. We record an unprecedented range of kinematical configurations of o-Ps annihilations into three photons. Tomographic reconstruction of the annihilation points in a large medium allows single-event estimation of positronium spin orientation and, consequently, determination of the complete spectrum of angular correlation between the annihilation plane orientation and positronium spin, the non-vanishing expectation value of which would manifest CPT-violating effects. We find no violation at the precision level of 10^{−4}, with a fourfold improvement on the previous measurement. This work enables application of positronium-imaging techniques to study discrete symmetries in positronium decays.

scholarly journals Sensitivity of Discrete Symmetry Tests in the Positronium System with the J-PET Detector

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1268
Author(s):  
Aleksander Gajos
Keyword(s):  
Detection System ◽  
Discrete Symmetry ◽  
Bound State ◽  
Emission Tomography ◽  
Angular Correlations ◽  
Leptonic Sector ◽  
Positron Emission ◽  
Electron Positron ◽  
Order Of Magnitude ◽  
Symmetry Tests

Study of certain angular correlations in the three-photon annihilations of the triplet state of positronium, the electron–positron bound state, may be used as a probe of potential CP and CPT-violating effects in the leptonic sector. We present the perspectives of CP and CPT tests using this process recorded with a novel detection system for photons in the positron annihilation energy range, the Jagiellonian Positron Emission Tomography (J-PET). We demonstrate the capability of this system to register three-photon annihilations with an unprecedented range of kinematical configurations and to measure the CPT-odd correlation between positronium spin and annihilation plane orientation with a precision improved by at least an order of magnitude with respect to present results. We also discuss the means to control and reduce detector asymmetries in order to allow J-PET to set the first measurement of the correlation between positronium spin and momentum of the most energetic annihilation photon which has never been studied to date.

The 40Ca(p,2p)39K Reaction at 45.0 MeV

1973 ◽  
Vol 51 (9) ◽  
pp. 1012-1016 ◽  
Author(s):  
K. H. Bray ◽  
S. N. Bunker ◽  
Mahavir Jain ◽  
K. S. Jayaraman ◽  
C. A. Miller ◽  
...  
Keyword(s):  
Wave Function ◽  
Angular Correlation ◽  
Bound State ◽  
Distorted Wave ◽  
Final State ◽  
Angular Correlations ◽  
State Wave ◽  
Bound State Wave Function ◽  
T Matrix ◽  
Matrix Calculation

A study of the 40Ca(p,2p)39K reaction has been made for two states of 39K, the 1d3/2−1(g.s.) and 2s1/2−1(2.53 MeV). Angular correlations at symmetric, coplanar angles between 30 and 105° have been measured. The data are compared with a distorted wave t-matrix calculation which utilizes a nonlocal bound state wave function. A further comparison is made with the angular correlation for unequal energies of the final state protons.

scholarly journals Search for η-mesic 3He in non-mesonic final state

2019 ◽  
Vol 199 ◽  
pp. 02029 ◽  
Author(s):  
Oleksandr Rundel ◽  
Magdalena Skurzok ◽  
Aleksander Khreptak
Keyword(s):  
Bound State ◽  
Beam Momentum ◽  
Proton Scattering ◽  
Continuous Beam ◽  
Final State ◽  
Proton Proton ◽  
Momentum Change ◽  
Limit Value ◽  
Upper Limit ◽  
Beam Technique

The experiment on searching for η-mesic 3He nucleus was performed in May 2014 at COSY accelerator in Juelich by WASA-at-COSY Collaboration. The measurements were carried out using ramped beam technique which allows for the slow and continuous beam momentum change near the threshold of η meson creation. The luminosity was obtained based on pd → 3Heη reaction and quasielastic proton-proton scattering. The bound state of η-meson and 3He nucleus is searched for in pd → 3He2γ and pd → 3He6γ channels. The analysis is still in progress and the estimated upper limit value is on the level of few nanobarns.

A Dedicated Breast Positron Emission Tomography Scanner: Proof of Concept

2014 ◽  
Vol 45 (4) ◽  
pp. 435-439 ◽  
Author(s):  
Shyam M. Srinivas ◽  
Lacey R. Greene ◽  
Geoffrey M. Currie ◽  
Richard H. Freifelder ◽  
Janet R. Reddin ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Proof Of Concept ◽  
Positron Emission Tomography Scanner ◽  
Positron Emission

scholarly journals Searches for Violation of CPT Symmetry and Lorentz Invariance with Astrophysical Neutrinos

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 42
Author(s):  
Celio A. Moura ◽  
Fernando Rossi-Torres
Keyword(s):  
Gamma Ray ◽  
Lorentz Invariance ◽  
New Physics ◽  
Time Signal ◽  
Cpt Symmetry ◽  
Symmetry Violation ◽  
Oscillation Phase ◽  
Astrophysical Neutrinos ◽  
Charge Parity ◽  
Violation Of Lorentz Invariance

Neutrinos are a powerful tool for searching physics beyond the standard model of elementary particles. In this review, we present the status of the research on charge-parity-time (CPT) symmetry and Lorentz invariance violations using neutrinos emitted from the collapse of stars such as supernovae and other astrophysical environments, such as gamma-ray bursts. Particularly, supernova neutrino fluxes may provide precious information because all neutrino and antineutrino flavors are emitted during a burst of tens of seconds. Models of quantum gravity may allow the violation of Lorentz invariance and possibly of CPT symmetry. Violation of Lorentz invariance may cause a modification of the dispersion relation and, therefore, in the neutrino group velocity as well in the neutrino wave packet. These changes can affect the arrival time signal registered in astrophysical neutrino detectors. Direction or time-dependent oscillation probabilities and anisotropy of the neutrino velocity are manifestations of the same kind of new physics. CPT violation, on the other hand, may be responsible for different oscillation patterns for neutrino and antineutrino and unconventional energy dependency of the oscillation phase or of the mixing angles. Future perspectives for possible CPT and Lorentz violating systems are also presented.

scholarly journals The tests of CP and CPT symmetry using the J-PET detector

2019 ◽  
Vol 199 ◽  
pp. 05027
Author(s):  
Muhsin Mohammed ◽  
Aleksander Gajos
Keyword(s):  
Particle Physics ◽  
Detection System ◽  
Experimental Tests ◽  
Reconstruction Technique ◽  
Positronium Atom ◽  
Cpt Symmetry ◽  
Elementary Particle Physics ◽  
Positron Emission ◽  
Cp Symmetry ◽  
Symmetry Tests

Symmetries under the parity transformation (P), charge-conjugation (C) and time reversal (T) are of fundamental importance in nuclear and elementary particle physics. Studies of the observables violating the combined CP symmetry constitute precise tests of the Standard Model. However, CP violation was observed to date only for systems involving quarks, raising the importance of searches its manifestations e.g. in purely leptonic systems. The 3γ decay of spin-aligned ortho-positronium atoms (o-Ps) can be used to test CP invariance in such a purely leptonic system. The Jagiellonian Positron Emission Tomograph (J-PET) detection system enables experimental tests of CP and CPT through measurement of the expectation values of angular correlation operators odd under these transformations and constructed from (i) spin vector of the ortho-positronium atom, (ii) co-planar momentum vectors of photons originating from the decay of the positronium atom, and (iii) linear polarization direction of annihilation photons. Precise experimental symmetry tests with J-PET are possible thanks to a dedicated reconstruction technique of 3γ ortho-positronium decays and a positronium production chamber including a highly porous aerogel target, whose setup allows for determining the orthopositronium spin polarization without the use of an external magnetic field.

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