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Статті в журналах з теми "Photon annihilation"

Автор: Grafiati

Опубліковано: 10 березня 2023

Оновлено: 11 березня 2023

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1

Gajos, Aleksander. "Sensitivity of Discrete Symmetry Tests in the Positronium System with the J-PET Detector." Symmetry 12, no. 8 (August 1, 2020): 1268. http://dx.doi.org/10.3390/sym12081268.

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Анотація:

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.

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2

Fanchiotti, H., C. A. García Canal, and V. Vento. "Multiphoton annihilation of monopolium." International Journal of Modern Physics A 32, no. 35 (December 20, 2017): 1750202. http://dx.doi.org/10.1142/s0217751x17502025.

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We show that due to the large coupling constant of the monopole–photon interaction the annihilation of monopole–antimonopole and monopolium into many photons must be considered experimentally. For monopole–antimonopole annihilation and lightly bound monopolium, even in the less favorable scenario, multiphoton events (four and more photons in the final state) are dominant, while for strongly bound monopolium, although two photon events are important, four- and six-photon events are also sizable.

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3

Gertsen, Anders S., Mads Koerstz, and Kurt V. Mikkelsen. "Benchmarking triplet–triplet annihilation photon upconversion schemes." Physical Chemistry Chemical Physics 20, no. 17 (2018): 12182–92. http://dx.doi.org/10.1039/c8cp00588e.

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4

Lingenfelter, Richard E., and Reuven Ramaty. "Annihilation Radiation and Gamma-Ray Continuum from the Galactic Center Region." Symposium - International Astronomical Union 136 (1989): 587–605. http://dx.doi.org/10.1017/s0074180900187091.

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Observations of the time-dependent, electron-positron annihilation line radiation and gamma-ray continuum emission from the region of the Galactic Center show that there are two components to the annihilation line emission: a variable, compact source at or near the Galactic Center, and a steady, diffuse interstellar distribution. We suggest that the annihilating positrons in the compact source, observed from 1977 through 1979, result from photon-photon pair production, most likely around an accreting black hole, and that the annihilating, interstellar positrons result from the decay of radionuclei produced by thermonuclear burning in supernovae.

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5

BRODSKY, STANLEY J. "HIGH ENERGY PHOTON–PHOTON COLLISIONS AT A LINEAR COLLIDER." International Journal of Modern Physics A 20, no. 31 (December 20, 2005): 7306–32. http://dx.doi.org/10.1142/s0217751x05031137.

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Анотація:

High intensity back-scattered laser beams will allow the efficient conversion of a substantial fraction of the incident lepton energy into high energy photons, thus significantly extending the physics capabilities of an e-e± linear collider. The annihilation of two photons produces C = + final states in virtually all angular momentum states. An important physics measurement is the measurement of the Higgs coupling to two photons. The annihilation of polarized photons into the Higgs boson determines its fundamental H0γγ coupling as well as determining its parity. Other novel two-photon processes include the two-photon production of charged pairs τ+τ-, W+W-, [Formula: see text], and supersymmetric squark and slepton pairs. The one-loop box diagram leads to the production of pairs of neutral particles such as γγ → Z0Z0, γZ0, and γγ. At the next order one can study Higgstrahlung processes, such as γγ → W+W-W-H. Since each photon can be resolved into a W+W- pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying possibly anomalous WW collisions and annihilation. In the case of QCD, each photon can materialize as a quark anti-quark pair which interact via multiple gluon exchange. The diffractive channels in photon-photon collisions allow a novel look at the QCD pomeron and odderon. The C = - odderon exchange contribution can be identified by looking at the heavy quark asymmetry. In the case of eγ → e′ collisions, one can measure the photon structure functions and its various components. Exclusive hadron production processes in photon-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes which are also important for the analysis of exclusive semi-leptonic and two-body hadronic B-decays.

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6

Mohammed Ahmed, Elaf, Hadi J. M. Al-Agealy, and Nada Farhan Kadhim. "Theoretical Calculation of Photon Emission from Quark-Antiquark Annihilation Using QCD Theory." Ibn AL-Haitham Journal For Pure and Applied Sciences 35, no. 4 (October 20, 2022): 37–44. http://dx.doi.org/10.30526/35.4.2879.

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Анотація:

In this work, we calculate and analyze the photon emission from quark and anti-quark interaction during annihilation process using simple model depending on phenomenology of quantum chromodynamic theory (QCD). The parameters, which include the running strength coupling, temperature of the system and the critical temperature, carry information regarding photon emission and have a significant impact on the photons yield. The emission of photon from strange interaction with anti-strange is large sensitive to decreases or increases there running strength coupling. The photons emission increases with decreases running strength coupling and vice versa. We introduce the influence of critical temperature on the photon emission rate in order to facilitate its further applied in photon emission spectrum. Photon emission was increased with large critical temperature MeV comparing with photons emission at critical temperature MeV. We analyze and discuss the sensitive of the emission of photon to photons energy . It increases with decreased photons energy and vice versa. However, the photons emission increases with increases thermal energy of system T = 170 MeV to 270 Mev. It is implied that strength coupling, critical temperature and photons energy can be as important as thermal energy of system for emission of photon.

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7

Chiba, M., J. Nakagawa, H. Tsugawa, R. Ogata, and T. Nishimura. "A detector with high detection efficiency in 4- and 5-photon-positronium annihilations." Canadian Journal of Physics 80, no. 11 (November 1, 2002): 1287–95. http://dx.doi.org/10.1139/p02-107.

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We first measured 4- and 5-photon annihilations in positronium using a multiphoton spectrometer (UNI), which consists of 32 NaI(Tl) scintillators with lead shields, each being located on a surface of an icosidodecahedron. The front face of each scintillator is placed at a distance of L = 262 mm from the center of the UNI. With this setup, the detection efficiency of 4- and 5-photon-annihilation processes are too small to get a sufficient number of events to analyze the physics. To obtain a larger detection efficiency, we must set the NaI(Tl) scintillators closer to the target. The original principle in designing the UNI was to suppress backgrounds (BG) and make them as low as possible allowing modest efficiencies for 4- and 5-photon-annihilation events, i.e., to get the highest signal-to-noise ratio (S/N). The new concept is to get the highest S/σ where σ is an error of one standard deviation of the signal including BG effects. A higher S/σ means a larger number of events with smaller BG taking into account a statistical effect. The detection efficiencies with BG effects are studied with respect to L using a detector simulator based on the EGS4 code in which 2- to 5-photon-annihilation events are generated by quantum-electrodynamic processes based on GRACE and BASES/SPRING codes. As a result, the detection efficiency and S/σ of 5-photon annihilations at L = 136 mm are 529 and 17 times larger than those at L = 262 mm, respectively. PACS Nos.: 36.10Dr, 12.20Fv, 13.10+q

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8

AKSENOV, A. G., R. RUFFINI, I. A. SIUTSOU, and G. V. VERESHCHAGIN. "DYNAMICS AND EMISSION OF MILDLY RELATIVISTIC PLASMA." International Journal of Modern Physics: Conference Series 12 (January 2012): 1–9. http://dx.doi.org/10.1142/s2010194512006204.

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Анотація:

Initially optically thick (with τ = 3⋅107) spherically symmetric outflow consisting of electron-positron pairs and photons is considered. We do not assume thermal equilibrium, and include the two-body processes that occur in such plasma: Möller and Bhabha scattering of pairs, Compton scattering, two-photon pair annihilation, two-photon pair production, together with their radiative three-body variants: bremsstrahlung, double Compton scattering, and three-photon pair annihilation, with their inverse processes. We solve numerically the relativistic Boltzmann equations in spherically symmetric case for distribution functions of pairs and photons. Three epochs are considered in details: a) the thermalization, which brings initially nonequilibrium plasma to thermal equilibrium; b) the self-accelerated expansion, which we find in agreement with previous hydrodynamic studies and c) decoupling of photons from the expanding electron-positron plasma. Photon spectra are computed, and appear to be non thermal near the peak of the luminosity. In particular, the low energy part of the spectrum contain more power with respect to the black body one.

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9

Ahmed, Elaf Mohammed, Hadi J. M. Al-Agealy, and Nada Farhan Kadhim. "Theoretical Study of Photons Spectra around High Energy of Quark-antiquark Using QCD Theory." NeuroQuantology 20, no. 4 (April 6, 2022): 58–63. http://dx.doi.org/10.14704/nq.2022.20.4.nq22095.

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Анотація:

In this paper, we study and investigate the quark anti-quark interaction mechanism through the annihilation process. The production of photons in association with interaction quark and gluon in the annihilation process. We investigate the effect of critical temperature, strength coupling and photons energy in terms of the quantum chromodynamics model theory framework. We find that the use of large critical temperature Tc =134 allows us to dramatically increase the strength coupling of quarks interaction. Its sensitivity to decreasing in photons rate with respect to strength coupling estimates. We also discuss the effect of photons energy on the rate of the photon , such as energies in range (1.5 to 5 GeV).The photons rate increases association at Tc=116MeV with the more decreased photons energy compared with photos rate association n t Tc=116MeV. This relation of strength coupling a, critical temperature and photons energy are particularly relevant when parametrizing systematic photons emission.

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10

Ye, Chen, Victor Gray, Khushbu Kushwaha, Sandeep Kumar Singh, Paul Erhart, and Karl Börjesson. "Optimizing photon upconversion by decoupling excimer formation and triplet triplet annihilation." Physical Chemistry Chemical Physics 22, no. 3 (2020): 1715–20. http://dx.doi.org/10.1039/c9cp06561j.

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Perylene is a common annihilator in triplet–triplet annihilation photon upconversion schemes. It has however a tendency for excimer formation, which can be reduced by mono-alkylation without severely compromising the TTA-UC efficiency.

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11

Strizhak, A., D. Abdurashitov, A. Baranov, D. Borisenko, F. Guber, A. Ivashkin, S. Morozov, S. Musin, and V. Volkov. "Setup to study the Compton scattering of entangled annihilation photons." Journal of Physics: Conference Series 2374, no. 1 (November 1, 2022): 012041. http://dx.doi.org/10.1088/1742-6596/2374/1/012041.

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The experimental setup to study the difference between Compton scattering of entangled and decoherent annihilation photons is discussed. The pairs of entangled gammas are born in electron-positron annihilation at rest. The polarization state of each photon in such a pair is not definite and represents the superposition of horizontal and vertical polarizations, while the relative polarizations of the photons are orthogonal. After interaction with the environment (for example, via the Compton scattering) the entangled pair of photons is broken and the pair becomes decoherent with determined polarizations of both gammas. Since the Compton scattering depends on the polarization of the initial photon, the scattering kinematics of entangled and decoherent photons might be quite different. At present, there is no experimental comparison of the Compton scattering kinematics for entangled and decoherent gammas.

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12

Albicocco, P., R. Assiro, F. Bossi, P. Branchini, B. Buonomo, V. Capirossi, E. Capitolo, et al. "Commissioning of the PADME experiment with a positron beam." Journal of Instrumentation 17, no. 08 (August 1, 2022): P08032. http://dx.doi.org/10.1088/1748-0221/17/08/p08032.

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Abstract The PADME experiment is designed to search for a hypothetical dark photon A' produced in positron-electron annihilation using a bunched positron beam at the Beam Test Facility of the INFN Laboratori Nazionali di Frascati. The expected sensitivity to the A' -photon mixing parameter ϵ is 10-3, for A' mass ≤ 23.5 MeV/c 2 after collecting ∼ 1013 positrons-on-target. This paper presents the PADME detector status after commissioning in July 2019. In addition, the software algorithms employed to reconstruct physics objects, such as photons and charged particles, and the calibration procedures adopted are illustrated in detail. The results show that the experimental apparatus reaches the design performance, and is able to identify and measure standard electromagnetic processes, such as positron bremsstrahlung and electron-positron annihilation into two photons.

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13

Ronchi, Alessandra, and Angelo Monguzzi. "Sensitized triplet–triplet annihilation based photon upconversion in full organic and hybrid multicomponent systems." Chemical Physics Reviews 3, no. 4 (December 2022): 041301. http://dx.doi.org/10.1063/5.0112032.

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In the last 15 years, the attention dedicated to organic conjugated systems experienced outstanding growth because of the renewed interest in mechanisms involving triplet states such as singlet fission, thermally activated delayed fluorescence, and intersystem crossing enhanced phosphorescence. Photon upconversion via sensitized triplet–triplet annihilation ( sTTA) enables the conversion of low-energy photons into high-energy ones, and it has been proposed in multicomponent systems as an efficient managing strategy of non-coherent photons. This mechanism exploits the annihilation of two optically dark triplet states of emitter moieties to produce high-energy photons. The annihilating triplets are sensitized through Dexter energy transfer by a light-harvester, typically a conjugated molecule or a nanocrystal, so sTTA upconversion is usually performed in bi-component systems. The high yield observed at low excitation intensities stimulated thriving research in the field, leading to the development of a large family of fully organic and hybrid sTTA multicomponent upconverters. Here, we compare the evolution of these two families of systems with respect to the sTTA upconversion main figures of merit, highlighting the strengths and weaknesses of both approaches, according to the results reported in the literature. The data presented are also discussed in the perspective of future developments in the field, pointing out the challenges that are still to be faced for the technological use of the sTTA upconversion process.

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14

Durandin, Nikita A., Jussi Isokuortti, Alexander Efimov, Elina Vuorimaa-Laukkanen, Nikolai V. Tkachenko, and Timo Laaksonen. "Efficient photon upconversion at remarkably low annihilator concentrations in a liquid polymer matrix: when less is more." Chemical Communications 54, no. 99 (2018): 14029–32. http://dx.doi.org/10.1039/c8cc07592a.

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15

Ladinsky, Glenn A. "Three-jet process in virtual photon-photon annihilation." Physical Review D 39, no. 9 (May 1, 1989): 2515–26. http://dx.doi.org/10.1103/physrevd.39.2515.

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16

Georgiev, A., M. Misheva, P. Mishev, G. Toumbev, and N. Vinarov. "Spectrometer for the study of three-photon annihilation of three-photon annihilation of positrons." Crystal Research and Technology 23, no. 3 (March 1988): 451–54. http://dx.doi.org/10.1002/crat.2170230332.

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17

Czerwiński, Eryk, Catalina Curceanu, Kamil Dulski, Aleksander Gajos, Marek Gorgol, Andrzej Heczko, Beatrix C. Hiesmayr, et al. "Studies of discrete symmetries in decays of positronium atoms." EPJ Web of Conferences 181 (2018): 01019. http://dx.doi.org/10.1051/epjconf/201818101019.

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Анотація:

A positronium - a bound state of electron and positron - is an eigenstate of parity and charge conjugation operators which decays into photons. It is a unique laboratory to study discrete symmetries whose precision is limited, in principle, by the effects due to the weak interactions expected at the level of 10−14 and photon-photon interactions expected at the level of 10−9. The Jagiellonian Positron Emission Tomograph (J-PET) is a detector for medical imaging as well as for physics studies involving detection of electronpositron annihilation into photons. The physics case covers the areas of discrete symmetries studies and genuine multipartite entanglement. The J-PET detector has high angular and time resolution and allows for determination of spin of the positronium and the momenta and polarization vectors of annihilation quanta. In this article, we present the potential of the J-PET system for studies of discrete symmetries in decays of positronium atoms.

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18

Ahmed, Elaf Mohammed, Hadi J. M. Al-Agealy, and Nada Farhan Kadhim. "Study of Photons Emission Rate of Quark-Antiquark at Higher Energy." Al-Mustansiriyah Journal of Science 33, no. 4 (December 30, 2022): 146–52. http://dx.doi.org/10.23851/mjs.v33i4.1193.

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In this paper, the dynamic of quark and anti-quark interaction has been used to study the production of photons in the annihilation process based on the theory of chromodynamic. The rate of the photon is to be calculated for charm and anti-strange interaction c→γg system with critical temperature 113 and 130 MeV and photon energy GeV/c. Here the critical temperature, strength coupling and photons energy are assumed to be affected dramatically on the rate of photons emission of state interaction c, which can form gluon possible structures and photon emission state. The decreased photons emission yields with increased strength couple of quarks reaction due to increase critical temperature from 113 MeV to 130 MeV were predicted. We can be found less difference in photons rate for the two different critical temperatures and strength coupling.

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19

Brodsky, Stanley J. "Physics Opportunities at a Photon–Photon Collider." International Journal of Modern Physics A 18, no. 16 (June 30, 2003): 2871–92. http://dx.doi.org/10.1142/s0217751x03016343.

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Анотація:

The advent of back-scattered laser beams for e±e-colliders will allow detailed studies of a large array of high energy γγ and γe collision processes with polarized beams. These include tests of electroweak theory in photon-photon annihilation such as γγ → W+W-, γγ → Higgs bosons, and higher-order loop processes, such as γγ → γγ, Zγ, H0Z0and ZZ. Methods for measuring the anomalous magnetic and quadrupole moments of the W and Z gauge bosons to high precision in polarized electron-photon and photon-photon collisions are discussed. Since each photon can be resolved into a W+W-pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. I also review high energy γγ and eγ tests of quantum chromodynamics, including the production of two gluon jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Exclusive hadron production processes in photon-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes which are also important for the analysis of exclusive semi-leptonic and two-body hadronic B-decays.

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20

Ye, Changqing, Liwei Zhou, Xiaomei Wang, and Zuoqin Liang. "Correction: Photon upconversion: from two-photon absorption (TPA) to triplet–triplet annihilation (TTA)." Physical Chemistry Chemical Physics 18, no. 10 (2016): 7537. http://dx.doi.org/10.1039/c6cp90051h.

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21

Kalashnikov, N. P., E. A. Mazur, and A. S. Olczak. "Annihilation of relativistic positrons in single crystal with production of one photon." International Journal of Modern Physics A 30, no. 22 (August 5, 2015): 1550137. http://dx.doi.org/10.1142/s0217751x15501377.

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The energy and momentum conservation laws prohibit positron–electron single-photon annihilation in vacuum. It is shown that the situation is different in a single crystal with one of the leptons (e.g. positron) moving in the channeling (or in the quasi-channeling) mode. The transverse motion of an oriented or channeled particle may sharply increase the probability of the single-photon annihilation process.

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22

Singh, S. Somorendro, and Yogesh Kumar. "Photon production in high energy nuclear collision of quark–gluon plasma." International Journal of Modern Physics A 29, no. 22 (August 29, 2014): 1450110. http://dx.doi.org/10.1142/s0217751x14501103.

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Анотація:

We extend to investigate photon production through annihilation with scattering (AWS), and Compton and annihilation processes from a stabilized high energy nuclear collision of quark–gluon plasma (QGP) incorporating finite value of quark mass obtained through a strong coupling value. The production rate is represented in the region of low and intermediate photon energy and it is observed to be a decreasing function with temperature. The calculation is extended to the case of photon spectra with the photon transverse momentum. The current observation shows little enhancement in both processes at the temperature T = 0.25 GeV and it is in conformity with the recent direct photon production of other works at temperature T = 0.30 GeV .

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23

Massaro, D., C. Arina, J. Heisig, F. Maltoni, and O. Mattelaer. "Studying dark matter with MadDM: lines and loops." Journal of Physics: Conference Series 2156, no. 1 (December 1, 2021): 012073. http://dx.doi.org/10.1088/1742-6596/2156/1/012073.

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Abstract Automated tools for the computation of amplitudes and cross sections have become the backbone of phenomenological studies beyond the standard model. We present the latest developments in MadDM, a calculator of dark-matter observables based on MadGraph5_aMC@NLO. The new version enables the fully automated computation of loop-induced annihilation processes, relevant for indirect detection of dark matter. Of particular interest is the direct annihilation into photons, γγ, γX. These processes lead to monochromatic gamma-ray lines that are smoking-gun signatures for dark-matter annihilation in our Galaxy. MadDM computes the predictions for the expected photon fluxes near Earth and derives constraints from the gamma-ray line searches by Fermi-LAT and HESS. As an application, we present the implications for the parameter space of the Inert Doublet Model.

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24

Chung, Won Sang. "On the deformed photon-added and photon-subtracted states." Modern Physics Letters A 29, no. 32 (October 20, 2014): 1450174. http://dx.doi.org/10.1142/s0217732314501740.

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In this paper, we introduce the deformed algebra whose number operator is expressed in terms of the product of the creation operator and annihilation operator. We give some examples for these kinds of deformed algebras. For Arik–Coon's q-oscillator algebra, we discuss, especially, the photon-added states and the photon-subtracted states and construct their associated generation functions.

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25

Fernandez, E., W. T. Ford, N. Qi, A. L. Read, J. G. Smith, T. Camporesi, R. De Sangro, et al. "Direct Photon Production ine+e−Annihilation." Physical Review Letters 54, no. 2 (January 14, 1985): 95–98. http://dx.doi.org/10.1103/physrevlett.54.95.

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26

Mehta, C. L., Anil K. Roy, and G. M. Saxena. "Eigenstates of two-photon annihilation operators." Physical Review A 46, no. 3 (August 1, 1992): 1565–72. http://dx.doi.org/10.1103/physreva.46.1565.

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27

Gray, Victor, Ambra Dreos, Paul Erhart, Bo Albinsson, Kasper Moth-Poulsen, and Maria Abrahamsson. "Loss channels in triplet–triplet annihilation photon upconversion: importance of annihilator singlet and triplet surface shapes." Physical Chemistry Chemical Physics 19, no. 17 (2017): 10931–39. http://dx.doi.org/10.1039/c7cp01368j.

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28

Beery, Drake, Ashley Arcidiacono, Jonathan P. Wheeler, Jiaqi Chen, and Kenneth Hanson. "Harnessing near-infrared light via S₀ to T₁ sensitizer excitation in a molecular photon upconversion solar cell." Journal of Materials Chemistry C 10, no. 12 (2022): 4947–54. http://dx.doi.org/10.1039/d1tc05270e.

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Анотація:

An Osmium sensitizer and anthracene annihilator are incorporated into a metal ion linked multilayer photoanode that harnesses NIR light in an integrated triplet–triplet annihilation upconversion solar cell.

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29

Runburg, Jack, Eric J. Baxter, and Jason Kumar. "Constraining dark matter microphysics with the annihilation signal from subhalos." Journal of Cosmology and Astroparticle Physics 2022, no. 06 (June 1, 2022): 023. http://dx.doi.org/10.1088/1475-7516/2022/06/023.

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Abstract In the cold dark matter scenario, galactic dark matter halos are populated with a large number of smaller subhalos. Previous work has shown that dark matter annihilations in subhalos can generate a distinctive, non-Poisson signal in the gamma-ray photon counts probability distribution function (PDF). Here we show that the gamma-ray PDF also carries information about the velocity dependence of the dark matter annihilation cross section. After calculating the PDF assuming s-wave and Sommerfeld-enhanced annihilation, we perform a mock data analysis to illustrate how current and future observations can constrain the microphysics of the dark matter annihilation. We find that, with current Fermi data, and assuming a dark matter annihilation cross section roughly at the limit of current bounds from annihilation in dwarf spheroidal galaxies, one can potentially distinguish the non-Poissonian fluctuations expected from dark matter annihilation in subhalos from Poisson sources, as well as from dark matter models with an incorrect velocity-dependence. We explore how robust these results are to assumptions about the modeling of the galactic gamma-ray background, but further work is needed to determine the impact of realistic astrophysical source populations on our results. We also point out a four-parameter degeneracy between the velocity dependence of the dark matter annihilation, the minimum subhalo mass, the power law index of the subhalo mass function, and the normalization of the dark matter signal. This degeneracy can be broken with priors from N-body simulations or from observational constraints on the subhalo mass function.

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30

Ronchi, Alessandra, Paolo Brazzo, Mauro Sassi, Luca Beverina, Jacopo Pedrini, Francesco Meinardi, and Angelo Monguzzi. "Triplet–triplet annihilation based photon up-conversion in hybrid molecule–semiconductor nanocrystal systems." Physical Chemistry Chemical Physics 21, no. 23 (2019): 12353–59. http://dx.doi.org/10.1039/c9cp01692a.

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Photon up-conversion based on triplet–triplet annihilation (TTA) in a hybrid system exploits the annihilation of optically dark triplets of an organic emitter, sensitized by a semiconductor nanocrystal, to produce high-energy singlets that generate high energy emission.

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31

Kiriu, Kenny, Jason Kumar, and Jack Runburg. "The velocity-dependent J-factor of the Milky Way halo: does what happens in the galactic bulge stay in the galactic bulge?" Journal of Cosmology and Astroparticle Physics 2022, no. 11 (November 1, 2022): 030. http://dx.doi.org/10.1088/1475-7516/2022/11/030.

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Abstract We consider the angular distribution of the photon signal which could arise from velocity-dependent dark matter annihilation within the Galactic bulge. We find that, for the case of Sommerfeld-enhanced annihilation, dark matter annihilation within the bulge is dominated by slow speed particles which never leave the bulge, allowing one to find a simple analytic relationship between the dark matter profile within the Galactic bulge and the angular distribution. On the other hand, for the case p- or d-wave annihilation, we find that the small fraction of high-speed particles which can leave the bulge provide a significant, often dominant, contribution to dark matter annihilation within the bulge. For these scenarios, fully understanding dark matter annihilation deep within the Galactic bulge, and the angular distribution of the resulting photon signal, requires an understanding of the dark matter profile well outside the bulge. We consider the Galactic Center excess in light of these results, and find that an explanation of this excess in terms of p-wave annihilation would require the dark matter profile within the bulge to have a much steeper profile than usually considered, but with uncertainties related to the behavior of the profile outside the bulge.

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32

Lange, Lucas, Frank Schäfer, Alexander Biewald, Richard Ciesielski, and Achim Hartschuh. "Controlling photon antibunching from 1D emitters using optical antennas." Nanoscale 11, no. 31 (2019): 14907–11. http://dx.doi.org/10.1039/c9nr03688a.

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We show that optical nanoantennas can be used to control the photon emission statistic of 1D nanostructures and to convert them into single-photon sources through enhanced exciton–exciton annihilation and an amplified radiative rate.

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33

YANG, MAO-ZHI. "THE CONTINUUM AND INTERFERENCE EFFECT IN $e^+e^-\to D^0\bar{D}^0$, D+D- Processes." Modern Physics Letters A 23, no. 36 (November 30, 2008): 3113–21. http://dx.doi.org/10.1142/s0217732308026406.

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In the e+e- annihilation processes [Formula: see text], D+D- near or above the threshold of [Formula: see text], there are not only the resonance contribution [Formula: see text], D+D-, but also the continuum contribution through virtual photon directly [Formula: see text], D+D-. The amplitudes through virtual photon directly and through resonance can interfere seriously. We consider the continuum and interference effect in the [Formula: see text] production process in e+e- annihilation. We find that the effect is significant near and above the threshold of the [Formula: see text] mesons.

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34

Pérez-Ríos, Jesús, Sherwin T. Love, and Chris H. Greene. "Two-photon total annihilation of molecular positronium." EPL (Europhysics Letters) 109, no. 6 (March 1, 2015): 63002. http://dx.doi.org/10.1209/0295-5075/109/63002.

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35

Ullio, Piero, and Lars Bergström. "Neutralino annihilation into a photon and aZboson." Physical Review D 57, no. 3 (February 1, 1998): 1962–71. http://dx.doi.org/10.1103/physrevd.57.1962.

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36

Kalashnikov, N. P., E. I. Mulyarchik, and A. S. Olchak. "Single-photon Annihilation of the Channeled Positrons." Physics Procedia 74 (2015): 165–68. http://dx.doi.org/10.1016/j.phpro.2015.09.180.

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37

Charalambous, S., M. Chardalas, S. Dedoussis, C. A. Eleftheriadis, and A. K. Liolios. "Parameters affecting three-photon positron annihilation spectrometers." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 300, no. 2 (January 1991): 297–302. http://dx.doi.org/10.1016/0168-9002(91)90440-2.

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38

Andersson, B., G. Gustafson, and C. Sjögren. "Prompt photon production in e+e− annihilation." Nuclear Physics B 380, no. 3 (August 1992): 408–22. http://dx.doi.org/10.1016/0550-3213(92)90251-6.

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39

Diehl, M., P. Kroll, and C. Vogt. "Two-photon annihilation into baryon-antibaryon pairs." European Physical Journal C 26, no. 4 (February 2003): 567–77. http://dx.doi.org/10.1140/epjc/s2002-01075-4.

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40

Lee, Su-Yong, Jiyong Park, Se-Wan Ji, C. H. Raymond Ooi, and Hai-Woong Lee. "Nonclassicality generated by photon annihilation-then-creation and creation-then-annihilation operations." Journal of the Optical Society of America B 26, no. 8 (July 8, 2009): 1532. http://dx.doi.org/10.1364/josab.26.001532.

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41

Zheleznyakov, V. V., and A. A. Litvinchuk. "One-photon and two-photon annihilation lines in gamma-bursts, II." Astrophysics and Space Science 112, no. 1 (1985): 25–49. http://dx.doi.org/10.1007/bf00668407.

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42

Ye, J. B., B. Z. Yang, X. W. Tang, and Q. Zhu. "Measurement of photon polarization from the three-photon annihilation of orthopositronium." Physics Letters A 133, no. 6 (November 1988): 309–11. http://dx.doi.org/10.1016/0375-9601(88)90450-1.

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43

Zheleznyakov, V. V., and A. A. Litvinchuk. "One-photon and two-photon annihilation lines in gamma-bursts, I." Astrophysics and Space Science 109, no. 2 (1985): 293–307. http://dx.doi.org/10.1007/bf00651276.

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44

Baluschev, Stanislav, Kartheek Katta, Yuri Avlasevich, and Katharina Landfester. "Annihilation upconversion in nanoconfinement: solving the oxygen quenching problem." Materials Horizons 3, no. 6 (2016): 478–86. http://dx.doi.org/10.1039/c6mh00289g.

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45

Gray, Victor, Damir Dzebo, Angelica Lundin, Jonathan Alborzpour, Maria Abrahamsson, Bo Albinsson, and Kasper Moth-Poulsen. "Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet–triplet annihilation photon upconversion." Journal of Materials Chemistry C 3, no. 42 (2015): 11111–21. http://dx.doi.org/10.1039/c5tc02626a.

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46

Kozhuharov, Venelin. "Searching for dark sector with missing mass technique in fixed target experiments." EPJ Web of Conferences 212 (2019): 06001. http://dx.doi.org/10.1051/epjconf/201921206001.

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Currently, the existence of a dark sector almost completely decoupled from the Standard Model is a viable solution for numerous long-standing problems in physics, including the nature of dark matter and the muon anomalous magnetic moment. A new gauge mediator, the dark photon, could be the portal to this hidden sector. The most general probe to its existence is the missing mass technique which requires a precise knowledge of the initial state of the process but does not put constraints on the dark photon final states. The experimental approaches to the search for dark photons in positron-on-target annihilation and in mesons decay in flight are presented and the physics reach is discussed.

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47

Peng, Jiang, Xinyan Guo, Xinpeng Jiang, Dahui Zhao, and Yuguo Ma. "Developing efficient heavy-atom-free photosensitizers applicable to TTA upconversion in polymer films." Chemical Science 7, no. 2 (2016): 1233–37. http://dx.doi.org/10.1039/c5sc03245h.

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48

Yonemura, Hiroaki, Yuji Naka, Mitsuhiko Nishino, Hiroshi Sakaguchi, and Sunao Yamada. "Switch of the magnetic field effect on photon upconversion based on sensitized triplet–triplet annihilation." Photochemical & Photobiological Sciences 15, no. 12 (2016): 1462–67. http://dx.doi.org/10.1039/c6pp00264a.

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49

Dzebo, Damir, Kasper Moth-Poulsen, and Bo Albinsson. "Robust triplet–triplet annihilation photon upconversion by efficient oxygen scavenging." Photochemical & Photobiological Sciences 16, no. 8 (2017): 1327–34. http://dx.doi.org/10.1039/c7pp00201g.

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50

VETTER, PAUL A. "EXPERIMENTAL TESTS OF FUNDAMENTAL SYMMETRIES IN POSITRONIUM ANNIHILATION." International Journal of Modern Physics A 19, no. 23 (September 20, 2004): 3865–78. http://dx.doi.org/10.1142/s0217751x04020130.

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Using the Gammasphere array of high-purity germanium detectors at the 88" Cyclotron at Lawrence Berkeley National Laboratory, we have made several measurements to test discrete fundamental symmetries in positronium annihilation. We tested charge conjugation symmetry (C) by searching for decays of ortho- and para-positronium to the "wrong" number of photons. We measured the five-photon annihilation mode of ortho-positronium, finding agreement with tree-level QED calculations at order α8. In a second experiment, we searched for decays of polarized ortho-positronium which violate the combined symmetry operation CPT. We improved existing limits on this CPT test by roughly a factor of ten. We are studying the feasibility of an experiment to search for "invisible" decays of ortho-positronium. Invisible decays could be caused by extra dimensions (invoked in string theories). General requirements for an experiment sensitive to decay branching ratios of order 10-9 are discussed.

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