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We analyze the $Z$-boson decay $Z\to \gamma\, X$ into a photon ($\gamma$) plus a hypothetical light boson ($X$) belonging to a dark or secluded sector. Due to its feeble interactions with Standard Model fields, this dark boson is behaving…

High Energy Physics - Phenomenology · Physics 2020-08-05 A. Comelato , E. Gabrielli

We report on a direct search for a three-body decay of the orthopositronium into a photon and two penetrating particles, o-Ps -> gamma + X1 + X2. The existence of this decay could explain the discrepancy between the measured and the…

High Energy Physics - Experiment · Physics 2008-11-26 A. Badertscher , P. Crivelli , M. Felcini , S. N. Gninenko , N. A. Goloubev , P. Nedelec , J. P. Peigneux , V. Postoev , A. Rubbia , D. Sillou

We consider a new three-nucleon force generated by the exchange of one pion in the presence of a 2N correlation. The underlying irreducible diagram has been recently suggested by the authors as a possible candidate to explain the puzzle of…

Nuclear Theory · Physics 2009-11-06 L. Canton , W. Schadow

Pseudo-spin symmetry in nuclei is investigated considering the Dirac equation with a Lorentz structured Woods-Saxon potential. The isospin correlation of the energy splittings of pseudo-spin partners with the nuclear potential parameters is…

Nuclear Theory · Physics 2009-11-06 P. Alberto , M. Fiolhais , M. Malheiro , A. Delfino , M. Chiapparini

We describe a high efficiency detector for measuring electron-positron pair transitions in nuclei. The device was built to be insensitive to gamma rays and to accommodate high overall event rates. The design was optimized for total pair…

Instrumentation and Detectors · Physics 2008-07-08 C. Tur , A. H. Wuosmaa , S. M. Austin , K. Starosta , J. Yurkon , A. Estrade , N. Goodman , J. C. Lighthall , G. Lorusso , S. T. Marley , J. Snyder

Recently, when examining the differential internal pair creation coefficients of $^8$Be, $^4$He and $^{12}$C nuclei, we observed peak-like anomalies in the angular correlation of the e$^+$e$^-$ pairs. This was interpreted as the creation…

Nuclear Experiment · Physics 2024-09-26 A. J. Krasznahorky , A. Krasznahorkay , M. Csatlós , J. Timár , M. Begala , A. Krakó , I. Rajta , I. Vajda , N. J. Sas

Observations of anomalies in the electron-positron angular correlations in high-energy decays in $^4$He, $^8$Be, and $^{12}$C have been reported recently by the ATOMKI collaboration. These could be explained by the creation and subsequent…

Nuclear Theory · Physics 2024-07-15 P. Gysbers , P. Navratil , K. Kravvaris , G. Hupin , S. Quaglioni

In recent years, the ATOMKI collaboration has performed a series of measurements of excited nuclei, observing a resonant excess of electron-positron pairs at large opening angles compared to the Standard Model prediction. The excess has…

High Energy Physics - Phenomenology · Physics 2026-02-13 Max H. Fieg , Toni Mäkelä , Tim M. P. Tait , Miša Toman

We investigate the signal $\gamma\gamma$ + missing energy in a high-energy linear $e^+e^-$ collider, with a view to differentiating between gauge-mediated supersymmetry breaking and the conventional supersymmetric models. Prima facie, there…

High Energy Physics - Phenomenology · Physics 2016-08-25 Biswarup Mukhopadhyaya , Sourov Roy

We determine the rates and energy and angular distributions of the positronium decays into a photon and a neutrino-antineutrino pair, Ps-->gamma+nu+anti-nu. We find that both positronium spin states have access to this decay channel,…

High Energy Physics - Phenomenology · Physics 2018-01-23 Andrzej Pokraka , Andrzej Czarnecki

The cross sections for the processes \gamma \nu --> \gamma\gamma \nu, \gamma\gamma -->\gamma\nu\bar{\nu} and \nu\bar{\nu} -->\gamma\gamma\gamma are calculated with the aid of an effective Lagrangian derived from the Standard model. These…

High Energy Physics - Phenomenology · Physics 2009-10-30 Duane A. Dicus , Wayne W. Repko

Second-order processes in physics is a research topic focusing attention from several fields worldwide including, for example, non-linear quantum electrodynamics with high-power lasers, neutrinoless double-$\beta$ decay, and stimulated…

New light, weakly coupled particles can be efficiently produced at existing and future high-intensity accelerators and radioactive sources in deep underground laboratories. Once produced, these particles can scatter or decay in large…

High Energy Physics - Phenomenology · Physics 2014-12-02 Eder Izaguirre , Gordan Krnjaic , Maxim Pospelov

On the basis of the idea of mixing (interaction) between the electron capture and the positron emission channels in the \beta^+ decay in the cases when both channels are energetically allowed, we attempt to explain oscillations of the…

Nuclear Theory · Physics 2010-04-23 V. I. Isakov

The cross sections for the processes $\gamma \nu\to \gamma \gamma \nu$, $\gamma\gamma\to\gamma\nu\bar{\nu}$ and $\nu\bar{\nu}\to\gamma\gamma\gamma$ are calculated for a range of center of mass energies from below $m_e$ to considerably above…

High Energy Physics - Phenomenology · Physics 2009-10-31 Duane A. Dicus , Chung Kao , Wayne W. Repko

Neutral stellar core at or over nuclear densities is described by a positive charged baryon core and negative charged electron fluid since they possess different masses and interactions. Based on a simplified model of a gravitationally…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Wen-Biao Han , Remo Ruffini , She-Sheng Xue

The decay of a massive pseudoscalar, scalar and U(1) boson into an electron-positron pair in the presence of strong electromagnetic backgrounds is calculated. Of particular interest is the constant-crossed-field limit, relevant for…

High Energy Physics - Phenomenology · Physics 2020-01-07 B. King , B. M. Dillon , K. A. Beyer , G. Gregori

We justify the feasibility of substituting a photon leg by a neutrino current in the Euler-Heisenberg Lagrangian to obtain an effective Lagrangian for the process $\gamma\nu\to\gamma\gamma \nu$ and its crossed reactions. We establish the…

High Energy Physics - Phenomenology · Physics 2009-10-31 A. Abada , J. Matias , R. Pittau

How does nature hold together protons and neutrons to form the wide variety of complex nuclei in the universe? Describing many-nucleon systems from the fundamental theory of quantum chromodynamics has been the greatest challenge in…

To this day, the two-slit electron interference pattern remains shrouded in an inordinate mystery. It continues to defy a logical and rational explanation. This paper will postulate a new "characteristic" pertaining to the electron. If this…

General Physics · Physics 2007-05-23 J. Zzimbe