We present a new method, exact in α^{'}, to explicitly compute string tree-level amplitudes involving one massive state and any number of massless ones. This construction relies on the so-called twisted heterotic string, which admits only gauge multiplets, a gravitational multiplet, and a single massive supermultiplet in its spectrum. In this simplified model, we determine the moduli-space integrand of all amplitudes with one massive state using Berends-Giele currents of the gauge multiplet. These integrands are then straightforwardly mapped to gravitational amplitudes in the twisted heterotic string and to the corresponding massive amplitudes of the conventional type-I and type-II superstrings.
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http://dx.doi.org/10.1103/PhysRevLett.127.051601 | DOI Listing |
Sci Rep
January 2025
Department of Information Technology, Faculty of Computers and Information, Assiut University, Assiut, Assiut, 71515, Egypt.
Fifth-generation (5G) communication technologies, such as millimeter wave communication, massive multiple-input-multiple-output and non-orthogonal-multiple-access (NOMA) are playing a pivotal role in promoting the modern applications of the Internet-of-Things. Using non-orthogonal resource allocation, NOMA can increase spectrum efficiency and achieve wide connectivity with low transmission delay and signaling cost. Despite the high potential of NOMA in 5G communications, NOMA is susceptible to a pilot contamination attack (PCA), in which an attacker resents the same pilot signals as authorized users.
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January 2025
State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China.
Hong-Ou-Mandel (HOM) interference is the foundation of quantum optics to test the degree of indistinguishability of two incoming photons, playing a key role in quantum communication, sensing, and photonic quantum computing. Realizing high-visibility HOM interference with massively parallel optical channels is challenging due to the lack of available natural optical references for aligning independent arrayed laser pairs. Here, we demonstrate 50 parallel comb-teeth pairs of continuous-wave weak coherent photons HOM interference using two independently frequency post-aligned soliton microcombs (SMCs), achieving an average fringe visibility over 46%.
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January 2024
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997 Russian Federation.
The growing incidence of infections caused by antibiotic-resistant strains of pathogens is one of the key challenges of the 21 century. The development of novel technological platforms based on single-cell analysis of antibacterial activity at the whole-microbiome level enables the transition to massive screening of antimicrobial agents with various mechanisms of action. The microbiome of wild animals remains largely underinvestigated.
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January 2025
Departamento de Física Teórica, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
We use digital quantum computing to simulate the creation of particles in a dynamic spacetime. We consider a system consisting of a minimally coupled massive quantum scalar field in a spacetime undergoing homogeneous and isotropic expansion, transitioning from one stationary state to another through a brief inflationary period. We simulate two vibration modes, positive and negative for a given field momentum, by devising a quantum circuit that implements the time evolution.
View Article and Find Full Text PDFArch Sex Behav
January 2025
Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz (INI-Fiocruz), Rio de Janeiro, Brazil.
Perceived risk for HIV acquisition among gay, bisexual, and other men who have sex with men (GBMSM) may not align with their actual sexual HIV exposure. Factors associated with low/moderate perceived risk among GBMSM eligible for pre-exposure prophylaxis (PrEP) (based on their high estimated HIV exposure) have been poorly described in Latin America. This is a secondary analysis of a 2018 web-based cross-sectional survey in Brazil, Mexico, and Peru.
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