Pub Date : 2023-01-20DOI: 10.1051/epjconf/202227402006
J. Gálvez-Viruet, M. Gómez-Rocha
Front-Form Hamiltonian dynamics provides a framework in which QCD’s vacuum is simple and states are boost invariant. However, canonical expressions are divergent and must be regulated in order to establish well-defined eigenvalue problems. The Renormalization Group Procedure for Effective Particles (RGPEP) provides a systematic way of finding counterterms and obtaining regulated Hamiltonians. Among its achievements is the description of asymptotic freedom, with a running coupling constant defined as the coefficient in front of the three gluon-vertex operators in the regulated Hamiltonian. However, the obtained results need a deeper understanding, since the coupling exhibits a finite dependence on the regularization functions, at least at the third-order term in the perturbative expansion. Here we present a similar derivation using a different regularization scheme based on massive gluons. The procedure can be extended to incorporate contributions from virtual fermions.
{"title":"Asymptotic freedom using a gluon mass as a regulator","authors":"J. Gálvez-Viruet, M. Gómez-Rocha","doi":"10.1051/epjconf/202227402006","DOIUrl":"https://doi.org/10.1051/epjconf/202227402006","url":null,"abstract":"Front-Form Hamiltonian dynamics provides a framework in which QCD’s vacuum is simple and states are boost invariant. However, canonical expressions are divergent and must be regulated in order to establish well-defined eigenvalue problems. The Renormalization Group Procedure for Effective Particles (RGPEP) provides a systematic way of finding counterterms and obtaining regulated Hamiltonians. Among its achievements is the description of asymptotic freedom, with a running coupling constant defined as the coefficient in front of the three gluon-vertex operators in the regulated Hamiltonian. However, the obtained results need a deeper understanding, since the coupling exhibits a finite dependence on the regularization functions, at least at the third-order term in the perturbative expansion. Here we present a similar derivation using a different regularization scheme based on massive gluons. The procedure can be extended to incorporate contributions from virtual fermions.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"247 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91449013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-19DOI: 10.1051/epjconf/202327606020
Hao Xu
In these proceedings, we present the three proposed observables to probe the neutron skin and symmetry energy with relativistic isobar collisions, namely, the isobar ratios of the produced hadron multiplicities (Nch), the mean transverse momenta (〈p⊥〉), and the net charge multiplicities (ΔQ). Our findings suggest potentially significant improvement to neutron skin and symmetry energy determination over traditional low energy methods.
{"title":"Probing neutron skin and symmetry energy with relativistic isobar collisions","authors":"Hao Xu","doi":"10.1051/epjconf/202327606020","DOIUrl":"https://doi.org/10.1051/epjconf/202327606020","url":null,"abstract":"In these proceedings, we present the three proposed observables to probe the neutron skin and symmetry energy with relativistic isobar collisions, namely, the isobar ratios of the produced hadron multiplicities (Nch), the mean transverse momenta (〈p⊥〉), and the net charge multiplicities (ΔQ). Our findings suggest potentially significant improvement to neutron skin and symmetry energy determination over traditional low energy methods.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"46 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91499889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-19DOI: 10.1051/epjconf/202327902001
R. Diehl, J. Greiner, M. Krause, Moritz M. M. Pleintinger, T. Siegert
Diffuse gamma-ray emission from the decay of radioactive 26Al is a messenger from the nucleosynthesis activity in our current-day galaxy. Because this material is attributed to ejections from massive stars and their supernovae, the gamma-ray signal includes information about nucleosynthesis in massive star interiors as it varies with evolutionary stages, and about their feedback on the surrounding interstellar medium. Our method of population synthesis of massive-star groups has been refined as a diagnostic tool for this purpose. It allows to build a bottom-up prediction of the diffuse gamma-ray sky when known massive star group distributions and theoretical models of stellar evolution and core-collapse supernova explosions are employed. We find general consistency of an origin in such massive-star groups, in particular we also find support for the clumpy distribution of such source regions across the Galaxy, and characteristics of large cavities around these. A discrepancy in the integrated 26Al gamma-ray flux is interpreted as an indication for excess 26Al emission from nearby, distributed in cavities that extend over major regions of the sky.
{"title":"Gamma-ray spectroscopy of galactic nucleosynthesis","authors":"R. Diehl, J. Greiner, M. Krause, Moritz M. M. Pleintinger, T. Siegert","doi":"10.1051/epjconf/202327902001","DOIUrl":"https://doi.org/10.1051/epjconf/202327902001","url":null,"abstract":"Diffuse gamma-ray emission from the decay of radioactive 26Al is a messenger from the nucleosynthesis activity in our current-day galaxy. Because this material is attributed to ejections from massive stars and their supernovae, the gamma-ray signal includes information about nucleosynthesis in massive star interiors as it varies with evolutionary stages, and about their feedback on the surrounding interstellar medium. Our method of population synthesis of massive-star groups has been refined as a diagnostic tool for this purpose. It allows to build a bottom-up prediction of the diffuse gamma-ray sky when known massive star group distributions and theoretical models of stellar evolution and core-collapse supernova explosions are employed. We find general consistency of an origin in such massive-star groups, in particular we also find support for the clumpy distribution of such source regions across the Galaxy, and characteristics of large cavities around these. A discrepancy in the integrated 26Al gamma-ray flux is interpreted as an indication for excess 26Al emission from nearby, distributed in cavities that extend over major regions of the sky.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80617653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-18DOI: 10.1051/epjconf/202328302014
A. Watson
Measurements of the Elongation Rate of the depth of shower maximum above 1 EeV are reviewed. There is evidence, from four independent estimates of this rate, made in the two hemispheres using three different techniques, for a decrease in the Elongation Rate above ~3 EeV, as first discovered by the Pierre Auger Collaboration over 15 year ago. Unless there is a dramatic change in the hadronic physics above this energy, the mean mass of the primary cosmic rays must increase as a function of energy, well into the decade beyond 10 EeV. To estimate the mass, the use of hadronic models is required, the accuracy of which remains uncertain. However, the possibility of a dramatic change in the hadronic physics appears unlikely, and would be inconsistent with data from the Auger Collaboration on the mass composition in the range 3 to 10 EeV, and on the anisotropy of arrival directions above 8 EeV. Both of these conclusions are insensitive to uncertainties in the shower models. Some remarks are made about the belief, still firmly held by some, that the highest-energy cosmic rays are dominantly protons.
{"title":"Model-independent Evidence for an Increase in the Mean Mass of Cosmic Rays above 3 EeV","authors":"A. Watson","doi":"10.1051/epjconf/202328302014","DOIUrl":"https://doi.org/10.1051/epjconf/202328302014","url":null,"abstract":"Measurements of the Elongation Rate of the depth of shower maximum above 1 EeV are reviewed. There is evidence, from four independent estimates of this rate, made in the two hemispheres using three different techniques, for a decrease in the Elongation Rate above ~3 EeV, as first discovered by the Pierre Auger Collaboration over 15 year ago. Unless there is a dramatic change in the hadronic physics above this energy, the mean mass of the primary cosmic rays must increase as a function of energy, well into the decade beyond 10 EeV. To estimate the mass, the use of hadronic models is required, the accuracy of which remains uncertain. However, the possibility of a dramatic change in the hadronic physics appears unlikely, and would be inconsistent with data from the Auger Collaboration on the mass composition in the range 3 to 10 EeV, and on the anisotropy of arrival directions above 8 EeV. Both of these conclusions are insensitive to uncertainties in the shower models. Some remarks are made about the belief, still firmly held by some, that the highest-energy cosmic rays are dominantly protons.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81284182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-18DOI: 10.1051/epjconf/202227401005
A. Shindler
We review the gradient flow for gauge and fermion fields and its applications to lattice gauge theory computations. Using specific examples, we discuss the interplay between perturbative and non-perturbative calculations in the context of renormalization with the gradient flow.
{"title":"Gradient Flow: Perturbative and Non-Perturbative Renormalization","authors":"A. Shindler","doi":"10.1051/epjconf/202227401005","DOIUrl":"https://doi.org/10.1051/epjconf/202227401005","url":null,"abstract":"We review the gradient flow for gauge and fermion fields and its applications to lattice gauge theory computations. Using specific examples, we discuss the interplay between perturbative and non-perturbative calculations in the context of renormalization with the gradient flow.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"123 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84940930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-11DOI: 10.1051/epjconf/202226601011
Stephen C. Richardson, J. Woods, Jake Daykin, J. Gorecki, R. Bek, N. Klokkou, James S. Wilkinson, M. Jetter, V. Apostolopoulos
We demonstrate epitaxially grown semiconductor membrane quantum well lasers on a SiO2/Si substrate lasing in a waveguide configuration, for potential uses as coherent light sources compatible with photonic integrated circuits. We study the emission characteristics of In0.13Ga0.87As/GaAs0.94P0.06 quantum well lasers, by using real and reciprocal space imaging. The laser cavity length is 424 μm, it emits light at 1 μm, and lasing thresholds as low as 211 mW were recorded. Control over the position and size of the laser spots by the pump was demonstrated.
{"title":"III-V compound semiconductor membrane quantum well waveguide lasers emitting at 1 μm","authors":"Stephen C. Richardson, J. Woods, Jake Daykin, J. Gorecki, R. Bek, N. Klokkou, James S. Wilkinson, M. Jetter, V. Apostolopoulos","doi":"10.1051/epjconf/202226601011","DOIUrl":"https://doi.org/10.1051/epjconf/202226601011","url":null,"abstract":"We demonstrate epitaxially grown semiconductor membrane quantum well lasers on a SiO2/Si substrate lasing in a waveguide configuration, for potential uses as coherent light sources compatible with photonic integrated circuits. We study the emission characteristics of In0.13Ga0.87As/GaAs0.94P0.06 quantum well lasers, by using real and reciprocal space imaging. The laser cavity length is 424 μm, it emits light at 1 μm, and lasing thresholds as low as 211 mW were recorded. Control over the position and size of the laser spots by the pump was demonstrated.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82345790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-10DOI: 10.1051/epjconf/202227106002
E. Friedman, A. Gal
A minimally constructed Λ-nucleus density-dependent optical potential is used to calculate binding energies of observed 1sΛ, 1pΛ states across the periodic table, leading to a repulsive ΛNN contribution D(3)Λ≈14 MeV to the phenomenological Λ-nucleus potential depth DΛ ≈ −30 MeV. This value is significant in connection with the so-called ’hyperon puzzle.’
{"title":"ΛNN content of Λ-nucleus potential","authors":"E. Friedman, A. Gal","doi":"10.1051/epjconf/202227106002","DOIUrl":"https://doi.org/10.1051/epjconf/202227106002","url":null,"abstract":"A minimally constructed Λ-nucleus density-dependent optical potential is used to calculate binding energies of observed 1sΛ, 1pΛ states across the periodic table, leading to a repulsive ΛNN contribution D(3)Λ≈14 MeV to the phenomenological Λ-nucleus potential depth DΛ ≈ −30 MeV. This value is significant in connection with the so-called ’hyperon puzzle.’","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"47 5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89590165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-03DOI: 10.1051/epjconf/202227405008
O. Oliveira, Vítor Paiva, P. Silva
The ghost propagator in Landau gauge is studied at finite temperature below and above Tc using lattice QCD simulations. For high temperatures, we find that the ghost propagator is enhanced, compared to the confined phase. The results suggest that the ghost propagator can be used to identify the phase transition, similarly to the gluon propagator case.
{"title":"Deconfinement in pure gauge SU(3) Yang-Mills theory: the ghost propagator","authors":"O. Oliveira, Vítor Paiva, P. Silva","doi":"10.1051/epjconf/202227405008","DOIUrl":"https://doi.org/10.1051/epjconf/202227405008","url":null,"abstract":"The ghost propagator in Landau gauge is studied at finite temperature below and above Tc using lattice QCD simulations. For high temperatures, we find that the ghost propagator is enhanced, compared to the confined phase. The results suggest that the ghost propagator can be used to identify the phase transition, similarly to the gluon propagator case.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84402770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-02DOI: 10.1051/epjconf/202227405005
J. Norman
Jet quenching has been one of the most important indicators that ultra-relativistic heavy-ion collisions produce a deconfined state of quarks and gluons, known as the Quark-Gluon Plasma. While the quenching of jets traditionally refers to the energy loss of high-momentum partons, the study of jet quenching has grown into a multi-pronged field where the measurement of jets and their modification in heavy-ion collisions is used as an important tool to study many aspects of QCD deconfinement. This contribution reviews the current experimental status of jets at the LHC and RHIC, and reports recent experimental highlights.
{"title":"Experimental Status of Jets in Heavy-Ion Collisions","authors":"J. Norman","doi":"10.1051/epjconf/202227405005","DOIUrl":"https://doi.org/10.1051/epjconf/202227405005","url":null,"abstract":"Jet quenching has been one of the most important indicators that ultra-relativistic heavy-ion collisions produce a deconfined state of quarks and gluons, known as the Quark-Gluon Plasma. While the quenching of jets traditionally refers to the energy loss of high-momentum partons, the study of jet quenching has grown into a multi-pronged field where the measurement of jets and their modification in heavy-ion collisions is used as an important tool to study many aspects of QCD deconfinement. This contribution reviews the current experimental status of jets at the LHC and RHIC, and reports recent experimental highlights.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85792557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1051/epjconf/202327801003
K. Mandal, S. Chaudhuri, F. Ruddy
Reactor dosimetry environments require radiation detectors that are capable of operating at high temperatures in extremely high neutron and gamma-ray dose rates. Silicon carbide (SiC) is one of the most promising wide bandgap semiconductors (3.27 eV) for harsh environment applications due to its radiation hardness, high breakdown voltage, high electron saturation velocity, and high thermal conductivity. In this paper, we summarize the prospect of Schottky barrier radiation detectors, fabricated on highly crystalline low-defect detector-grade n-type 4H-SiC epitaxial layers with thickness ranging from 20 to 250 lm, for harsh environment applications. A comprehensive discussion on the characterization of the parameters that influence the energy resolution has been included. The usage of electrical and radiation spectroscopic measurements for characterizing the junction and rectification properties, minority carrier diffusion lengths, and energy resolution has been elaborated. Characterization of crucial factors that limit the energy resolution of the detectors such as charge trap centers using thermally stimulated transient techniques is summarized. Finally, the effect of neutron fluence on the performance of the 4H-SiC detectors is discussed.
{"title":"Fabrication and characterization of high-resolution 4H-SiC epitaxial radiation detectors for challenging reactor dosimetry environments","authors":"K. Mandal, S. Chaudhuri, F. Ruddy","doi":"10.1051/epjconf/202327801003","DOIUrl":"https://doi.org/10.1051/epjconf/202327801003","url":null,"abstract":"Reactor dosimetry environments require radiation detectors that are capable of operating at high temperatures in extremely high neutron and gamma-ray dose rates. Silicon carbide (SiC) is one of the most promising wide bandgap semiconductors (3.27 eV) for harsh environment applications due to its radiation hardness, high breakdown voltage, high electron saturation velocity, and high thermal conductivity. In this paper, we summarize the prospect of Schottky barrier radiation detectors, fabricated on highly crystalline low-defect detector-grade n-type 4H-SiC epitaxial layers with thickness ranging from 20 to 250 lm, for harsh environment applications. A comprehensive discussion on the characterization of the parameters that influence the energy resolution has been included. The usage of electrical and radiation spectroscopic measurements for characterizing the junction and rectification properties, minority carrier diffusion lengths, and energy resolution has been elaborated. Characterization of crucial factors that limit the energy resolution of the detectors such as charge trap centers using thermally stimulated transient techniques is summarized. Finally, the effect of neutron fluence on the performance of the 4H-SiC detectors is discussed.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73758496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：