1,212 research outputs found

    Antisymmetric tensor contribution to the muon g-2

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    We investigate the Kalb-Ramond antisymmetric tensor field as solution to the muon g−2g-2 problem. In particular we calculate the lowest-order Kalb-Ramond contribution to the muon anomalous magnetic moment and find that we can fit the new experimental value for the anomaly by adjusting the coupling without affecting the electron anomalous magnetic moment results.Comment: 7 pages, 1 figur

    Radiolysis of Amino Acids by Heavy and Energetic Cosmic Ray Analogs in Simulated Space Environments: α\alpha-Glycine Zwitterion Form

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    In this work, we studied the stability of the glycine molecule in the crystalline zwitterion form, known as {\alpha}-glycine (+^{+}NH3_{3}CH2_{2}COO−^{-}) under action of heavy cosmic ray analogs. The experiments were conducted in a high vacuum chamber at heavy ions accelerator GANIL, in Caen, France. The samples were bombarded at two temperatures (14 K and 300 K) by 58^{58}Ni11+^{11+} ions of 46 MeV until the final fluence of 101310^{13} ions cm−2^{-2}. The chemical evolution of the sample was evaluated in-situ using Fourrier Transformed Infrared (FTIR) spectrometer. The bombardment at 14 K produced several daughter species such as OCN−^-, CO, CO2_2, and CN−^-. The results also suggest the appearing of peptide bonds during irradiation but this must be confirmed by further experiments. The halflives of glycine in Interstellar Medium were estimated to be 7.8 ×103\times 10^3 years (300 K) and 2.8 ×103\times 10^3 years (14 K). In the Solar System the values were 8.4 ×102\times 10^2 years (300 K) and 3.6 ×103\times 10^3 years (14 K). It is believed that glycine could be present in space environments that suffered aqueous changes such as the interior of comets, meteorites and planetesimals. This molecule is present in proteins of all alive beings. So, studying its stability in these environments provides further understanding about the role of this specie in the prebiotic chemistry on Earth.Comment: 28 pages, 12 figures, 9 tables. Accepted to be published at Monthly Notices of the Royal Astronomical Society (MNRAS

    Employing Soft X-rays in Experimental Astrochemistry

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    The presence of soft x-rays is very important for the chemical evolution of interstellar medium and other astrophysical environments close to young and bright stars. Soft X-rays can penetrate deep in molecular clouds and protostellar disks and trigger chemistry in regions in which UV stellar photons do not reach. The effects of soft X-rays in astrophysical ices are also remarkable because they release secondary electrons in and on the surface of the ices, which trigger a new set or chemical reactions. In this chapter we will discuss firstly about the origin and relevance of soft X-rays in astrophysics. Next we will move to the effect of ionizing radiation in organic molecules present in astrophysical environment. We will discuss the use soft X-rays in astrochemistry laboratory studies at both gas- and solid-phase (ice). We will make a review covering our publications in this field, in particular, about the experiments employing time-of-flight spectroscopy (TOF-MS), Fourier transform infrared (FTIR) spectroscopy and photon stimulated ion desorption (PSID-TOF-MS). This study help us to understand the chemical evolution several astrophysical regions and also put constrains in the researches related with the life's origin.Comment: 34 pages, 25 figures and 2 tables. This a book chapter of "X-Ray Spectroscopy" ISBN:978-953-307-967-7; InTech Open Access Publisher (http://www.intechweb.org/). Edited by Shatendra K. Sharma. Publication date: December 201
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