Letters in High Energy Physics http://journals.andromedapublisher.com/index.php/LHEP Andromeda Publishing And Academic Services LTD en-US Letters in High Energy Physics 2632-2714 <p align="justify">Letters in High Energy Physics (LHEP) is an open access journal published by Andromeda Publishing and Education Services. The articles in LHEP are distributed according to the terms of <a href="http://creativecommons.org/licenses/by/4.0" target="_blank" rel="noopener">the creative commons license CC-BY 4.0</a>. Under the terms of this license, copyright is retained by the author while use, distribution and reproduction in any medium are permitted provided proper credit is given to original authors and sources.</p> <h2 style="margin-bottom: 0px; margin-top: 0px;">Terms of Submission</h2> <p style="margin-top: 0px; margin-bottom: 0px;" align="justify">By submitting an article for publication in LHEP, the submitting author asserts that:</p> <p style="margin-top: 0px; margin-bottom: 0px;" align="justify">1. The article presents original contributions by the author(s) which have not been published previously in a peer-reviewed medium and are not subject to copyright protection.</p> <p style="margin-top: 0px; margin-bottom: 0px;" align="justify">2. The co-authors of the article, if any, as well as any institution whose approval is required, agree to the publication of the article in LHEP.</p> SModelS Database Update v1.2.3 http://journals.andromedapublisher.com/index.php/LHEP/article/view/158 <pre><br>We present an update of the SModelS database with simplified model results from 13 ATLAS and 10 CMS searches for supersymmetry at Run 2. This includes 5 ATLAS and 1 CMS analyses for full Run 2 luminosity, i.e., close to 140 fb\(^{-1}\) of data. In total, 76 official upper limit and efficiency map results have been added. Moreover, 21 efficiency map results have been produced by us using MadAnalysis5, to improve the coverage of gluino-squark production. The constraining power of the new database, v1.2.3, is compared to that of the previous release, v1.2.2. SModelS v1.2.3 is publicly available and can readily be employed for physics studies.</pre> <p>&nbsp;</p> Charanjit K. Khosa Sabine Kraml Andre Lessa Philipp Neuhuber Wolfgang Waltenberger ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-09-01 2020-09-01 10.31526/lhep.2020.158 Can Self-Replicating Species Flourish in the Interior of a Star? http://journals.andromedapublisher.com/index.php/LHEP/article/view/166 <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The existing view of biological life is that it evolves under suitable conditions in the low-temperature world of atoms and molecules on the surface of a planet. It is believed that any plausible extraterrestrial form of life must resemble the life on Earth that is ruled by biochemistry of nucleic acids, proteins, and sugars. Going against this dogma, we argue that an advanced form of life based upon short-lived species can exist inside main-sequence stars like our Sun.</p> </div> </div> </div> Luis A. Anchordoqui Eugene M. Chudnovsky ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-08-29 2020-08-29 10.31526/lhep.2020.166 A Generally Covariant Theory of Quantized Real Klein-Gordon Field in de Sitter Spacetime http://journals.andromedapublisher.com/index.php/LHEP/article/view/162 <p>We propose in this paper a quantization scheme for the real Klein-Gordon field in de Sitter spacetime.<br>Our scheme is generally covariant with the help of vierbein, which is necessary usually for the spinor<br>field in curved spacetime. We first present a Hamiltonian structure and then quantize the field following<br>the standard approach. For the free field, the time-dependent quantized Hamiltonian is diagonalized by<br>Bogliubov transformation, and the eigenstates at each instant are interpreted as the observed particle states</p> <p>at that instant. The interpretation is supported by the known cosmological redshift formula and the on-<br>shell condition of 4-momentum for a free field. Though mathematics is carried out in terms of conformal</p> <p>coordinates for the sake of convenience, the whole theory can be transformed into any other coordinates<br>based on general covariance. It is concluded that particle states, such as vacuum states in particular, are<br>time-dependent and vacuum states at one time evolve into nonvacuum states at later times. The formalism<br>of perturbation is provided with en extended Dirac picture.</p> Sze-Shiang Feng ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-08-21 2020-08-21 10.31526/lhep.2020.162 Normalization of the Ground State of the Supersymmetric Harmonic Oscillator http://journals.andromedapublisher.com/index.php/LHEP/article/view/160 <p>Supersymmetry plays a main role in all current thinking about superstring theory. Indeed, many remarkable properties of string theory have been explained using supersymmetry as a tool. So far, there has been<br>no unbroken supersymmetry observed in nature, and if nature is described by supersymmetry, it must be<br>broken. Supersymmetry may be broken spontaneously at any order of perturbation theory or dynamically<br>due to nonperturbative effects. To examine the methods of supersymmetry breaking, special attention is<br>given to discuss the normalization of the ground state of the supersymmetric harmonic oscillator. This<br>study explains that perturbation theory gives incorrect results for both the ground-state wave function<br>and the energy spectrum and it fails to give an explanation to the supersymmetry breaking.</p> Ahmed Ayad ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-07-30 2020-07-30 10.31526/lhep.2020.160 Effects of an H-μ-τ coupling in quarkonium lepton flavor violation decays http://journals.andromedapublisher.com/index.php/LHEP/article/view/152 <p>In this work we study the consistency of a possible non-vanishing coupling Hμτ smaller than 0.25% as pointed by the CMS collaborations [1], with measured lepton flavor violation processes involving quarkonium. We show that the most promising channel to confirm this excess is to look for the lepton flavor tau decay into a f<sub>0</sub> and μ where the experimental limit could strongly improved with the new B factories as Belle II.</p> David Delepine Mauro Napsuciale Eduardo Peinado ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-06-19 2020-06-19 10.31526/lhep.2020.152 Applying New Physics to the Problems of the \(\eta′\to\pi^0\gamma\gamma\) Decay http://journals.andromedapublisher.com/index.php/LHEP/article/view/156 <p>Rare decays of light mesons may be a discovery window for a new weakly coupled forces hidden at a low-energy QCD scale. BES-III Collaboration reported an observation of the rare decay \(\eta'&nbsp;\to\pi^0\gamma\gamma\). The observed decay width disagrees with the preliminary theoretical estimates. We show that this tension may be attributed to New Physics, presumably Dark Photon. For completeness, we consider a possible influence of New Physics on a similar well-measured decay \(\eta \to\pi^0\gamma\gamma\) and a recently measured one, \(\eta'&nbsp;\to\eta\gamma\gamma\), showing that the impact of the hypothetical Dark Photon may be also present in these decays.</p> Yaroslav Balytskyi ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-05-26 2020-05-26 10.31526/lhep.2020.156 The Thermodynamics of Relativistic Multi-Fluid Systems http://journals.andromedapublisher.com/index.php/LHEP/article/view/141 <p>This article extends the single-fluid relativistic irreversible thermodynamics theory of Müller, Israel and<br>Stewart (hereafter the MIS theory) to a multi-fluid system with inherent species interactions. This is illustrated<br>in a two-fluid toy-model where an effective complex 4-velocity plays the role of a primary dynamical<br>parameter. We find that an observer who resides in the real-part of this universe will notice that their<br>knowledge of the universe parametrized using real, rather than imaginary, quantities are insufficient to fully<br>determine properties such as the total energy density, pressure or entropy, In fact, such an observer will<br>deduce the existence of some negative energy that affects the expansion of their perceived real universe.</p> Bob Osano ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-04-01 2020-04-01 10.31526/lhep.2020.141 A Brief Introduction to the Weak Gravity Conjecture http://journals.andromedapublisher.com/index.php/LHEP/article/view/176 <pre><br>The Weak Gravity Conjecture proposes that a theory with a gauge field that is coupled to gravity must have charged matter on which gravity acts as the weakest force. It also proposes that there is an intrinsic cutoff on such an effective theory, which corresponds to a tower of charged states, that is set by the strength of the gauge coupling (in Planck units). This article is a brief introduction to the Weak Gravity Conjecture, covering aspects of the motivations for it as well as various extensions and refinements.</pre> Eran Palti ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2020-10-16 2020-10-16 10.31526/lhep.2020.176