Journal of Physics G最新文献

{"title":"The role of <i>U(1)_A </i> symmetry breaking in the QCD corrections to the pion mass difference","authors":"Mahammad Sabir Ali, Chowdhury Aminul Islam, Rishi Sharma","doi":"10.1088/1361-6471/acf9bc","DOIUrl":"https://doi.org/10.1088/1361-6471/acf9bc","url":null,"abstract":"Abstract The charged and neutral pion mass difference can be attributed to both the quantum electrodynamics and QCD contributions. The current quark mass difference (Δ m ) is the source of the QCD contribution. Here, in a two-flavour non-local Nambu–Jona-Lasinio model, we try to estimate the QCD contribution. Interestingly, we find that the strength of the <?CDATA $U{left(1right)}_{A}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mi>U</mml:mi> <mml:msub> <mml:mrow> <mml:mfenced close=\")\" open=\"(\"> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> </mml:mfenced> </mml:mrow> <mml:mrow> <mml:mi>A</mml:mi> </mml:mrow> </mml:msub> </mml:math> symmetry-breaking parameter c plays a crucial role in obtaining the pion mass difference while intertwined with the current quark mass difference. To obtain the QCD contribution for the pion mass difference, we scan the parameter space in {Δ m , c }, and by comparing this with the existing results, we constrained the parameter space. Further, using a fitted value of c , we determine the allowed range for the Δ m in the model. The model estimated Δ m ranges enable us to extract the chiral perturbation theory low energy constant, l 7 and verify the dependence of the pion mass difference on Δ m . We also find out its dependence on c —it increases with the decreasing value of c , i.e. toward an axial anomaly restored phase.","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923901","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}

{"title":"Corrigendum: Strangeness content of the pion in the U(3) Nambu–Jona–Lasinio model (2022 J. Phys. G: Nucl. Part. Phys. 49 055101)","authors":"Fábio L Braghin","doi":"10.1088/1361-6471/acf9bb","DOIUrl":"https://doi.org/10.1088/1361-6471/acf9bb","url":null,"abstract":"","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135480886","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}

{"title":"Unpolarized QED parton distribution functions in NLO","authors":"Andrej B Arbuzov, Uliana Voznaya","doi":"10.1088/1361-6471/acff7b","DOIUrl":"https://doi.org/10.1088/1361-6471/acff7b","url":null,"abstract":"Abstract Perturbative solutions for unpolarized QED parton distribution and fragmentation functions are presented explicitly in the next-to-leading logarithmic approximation. The scheme of iterative solution of QED evolution equations is described in detail. Terms up to $mathcal{O}(alpha^3L^2)$ are calculated analytically, where $L=ln(mu_F^2/m_e^2)$ is the large logarithm which depends on the factorization energy scale $mu_Fgg m_e$. The results are process independent and relevant for future high-precision experiments.","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135695863","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}

{"title":"Signatures of elongated and compact configurations in the fusion barrier distribution of deformed nuclei","authors":"Fatema Adel Fareed, Walaa Seif, Ahmed Adel, I.A.M. Abdul-Magead","doi":"10.1088/1361-6471/acff10","DOIUrl":"https://doi.org/10.1088/1361-6471/acff10","url":null,"abstract":"Abstract The fusion barrier distributions of 11 fusion reactions are investigated to understand the role of orientation as a degree of freedom in the fusion mechanism involving deformed nuclei, and seeking signatures of cold and hot fusion. We compared the experimentally extracted barrier distributions (BD) with those calculated using the coupled-channel method, starting from orientation-dependent folding potentials based on M3Y-Reid nucleon-nucleon interaction, with coupling to the anticipated vibrational and rotational excitations in projectile and target nuclei. We found that the signature of the hot fusion process within the compact configuration of the participating deformed nuclei is always evident in the extracted fusion barrier distribution. The different peaks appearing in the extracted BD can be individually assigned to elongated-cold or compact-hot fusion process. The imprint of the compact-hot fusion may also manifest itself as a little increase in the value of the BD at certain related energy, compared with the preceding and succeeding values. &amp;#xD;","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135829632","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}

{"title":"Optimization of convolutional neural networks for background suppression in the PandaX-III experiment","authors":"Shangning Xia, Suizhi Huang, Kexin Xu, Tao Li, Xun Chen, Ke Han, Shaobo Wang","doi":"10.1088/1361-6471/acfe24","DOIUrl":"https://doi.org/10.1088/1361-6471/acfe24","url":null,"abstract":"Abstract The tracks recorded by a gaseous detector provide a possibility for charged particle identi fication. For searching the neutrinoless double beta decay events of 136Xe in the PandaX-III experiment, we optimized the convolutional neural network based on the Monte Carlo simulation data to improve the signal-background discrimination power. EfficientNet is chosen as the baseline model and the optimization is performed by tuning the hyperparameters. In particular, the maximum discrimination power is achieved by optimizing the channel number of the top convolutional layer. In comparison with our previous work, the significance of discrimination has been improved by ∼70%.&amp;#xD;","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135345171","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}

{"title":"Hadron transverse momentum distributions in the Tsallis statistics with escort probabilities","authors":"Alexandru S. Parvan","doi":"10.1088/1361-6471/acfe23","DOIUrl":"https://doi.org/10.1088/1361-6471/acfe23","url":null,"abstract":"Abstract The exact and approximate hadron transverse momentum distributions for the Fermi-Dirac, Bose-Einstein and Maxwell-Boltzmann statistics of particles in the framework of the Tsallis statistics with escort probabilities (the Tsallis-3 statistics) have been derived. The classical and quantum transverse momentum distributions in the zeroth term approximation and the quantum transverse momentum distributions in the factorization approximation introduced in the zeroth term approximation were found. The transverse momentum distributions in the zeroth term approximation and in the factorization approximation of the zeroth term approximation are the same in the Tsallis-3, Tsallis-2 and $q$-dual statistics. The well-known classical phenomenological Tsallis distribution exactly coincides with the classical transverse momentum distribution of the Tsallis-3 statistics in the zeroth term approximation for which the entropy of system is zero in the whole range of state variables. However, the quantum phenomenological Tsallis distribution does not coincide with either the exact or approximate transverse momentum distributions of the Tsallis-3 statistics. The exact Tsallis-3 classical distribution and the classical phenomenological Tsallis distribution were applied to describe the experimental spectra of the charged pions produced in the proton-proton collisions at high energies. The values of the parameters $(T,q)$ for both these model distributions differ in the whole energy range. Thus, the classical phenomenological Tsallis distribution is an unsatisfactory approximation for the exact classical transverse momentum distribution of the Tsallis-3 statistics.","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135385671","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}

{"title":"Enhanced dilepton emission from a phase transition in dense matter","authors":"Oleh V. Savchuk, Anton Motornenko, Jan Steinheimer, Volodymyr Vovchenko, Marcus Bleicher, Mark I. Gorenstein, Tetyana Galatyuk","doi":"10.1088/1361-6471/acfccf","DOIUrl":"https://doi.org/10.1088/1361-6471/acfccf","url":null,"abstract":"Abstract It is demonstrated that the presence of a phase transition in heavy ion collisions, at beam energies that probe dense QCD matter, leads to a significant enhancement of the dilepton yield at low invariant mass and low beam energies per produced pion due to the extended emission time.&amp;#xD;In addition, the temperature of low mass dileptons shows a modest decrease due to the mixed phase.&amp;#xD;The emission of dileptons in the SIS18--SIS100 beam energies range is studied by augmenting the UrQMD transport model with a realistic density dependent equation of state, as well as two different phase transitions. This is achieved by extending the molecular dynamics interaction part of the UrQMD model to a density dependent interaction potential with a high density minimum leading to a phase transition and metastable coexisting high density states.&amp;#xD;Together with a high precision measurement these simulations will be able to constrain the existence of a phase transition in QCD up to densities of several times nuclear saturation density.","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135770649","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}

{"title":"Corrigendum: Alpha decay of thermally excited nuclei (2023 J. Phys. G: Nucl. Part. Phys. 50 015203)","authors":"J E Perez Velasquez, O L Caballero, N G Kelkar","doi":"10.1088/1361-6471/ace53f","DOIUrl":"https://doi.org/10.1088/1361-6471/ace53f","url":null,"abstract":"","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"217 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135396800","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}

{"title":"Extended analytical solutions of the Bohr Hamiltonian with the sextic oscillator: Pt-Os isotopes","authors":"Samira Baid, Géza Lévai, Jose M Arias","doi":"10.1088/1361-6471/acb78a","DOIUrl":"https://doi.org/10.1088/1361-6471/acb78a","url":null,"abstract":"Abstract The sextic oscillator adapted to the Bohr Hamiltonian has been used to describe even Pt and Os isotopes from A = 188 to 198 and A = 186 to 192, respectively. The purpose of this study was to investigate the possible transition from the γ -unstable to the spherical vibrator shape phases. In this setup the potential appearing in the Bohr Hamiltonian is independent from the γ shape variable, and the physical observables (energy eigenvalues, B ( E 2)) can be obtained in closed analytical form within the quasi-exactly solvable formalism for the model space containing 30 of the lowest-lying levels. Experimental energy levels have been associated with the theoretical ones. The available electric quadrupole transition data ( B ( E 2), decay preferences) have been taken into account in matching the experimental and theoretical levels. Special attention has been paid to transitions from the first two excited 0 + levels to the <?CDATA ${2}_{1}^{+}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> and <?CDATA ${2}_{2}^{+}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> levels, as these indicate the change of shape phases with spherical and deformed potential minimum. The three parameters of the Hamiltonian have been determined by a weighted least square fit procedure. Trends in the location of states belonging to the ground-state, the K π = 2 + and two excited K π = 0 + bands have been analysed. The trajectory determined by the fitted parameters in the two-dimensional phase space has also been plotted, and it has been found that all the nuclei are characterized by a deformed potential minimum, except for the heaviest Pt isotope ( 198 Pt), for which the transition to the spherical shape phase is realised. Although the spectroscopic information on the next isotopes of the chains ( 200 Pt and 194 Os) is far less complete, there are indications that these nuclei are also close to or fall within the domain of spherical potential minimum.","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"515 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136391032","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}

{"title":"Low-energy physics in neutrino LArTPCs","authors":"Caratelli, D., Foreman, W., Friedland, A., Gardiner, S., Gil-Botella, I., Karagiorgi, G., Kirby, M., Miotto, G. Lehmann, Littlejohn, B. R., Mooney, M., Reichenbacher, J., Sousa, A., Scholberg, K., Yu, J., Yang, T., Andringa, S., Asaadi, J., Bezerra, T. J. C., Capozzi, F., Cavanna, F., Church, E., Himmel, A., Junk, T., Klein, J., Lepetic, I., Li, S., Sala, P., Schellman, H., Sorel, M., Wang, J., Wang, M. H. L. S., Wu, W., Zennamo, J., Acero, M. A., Adames, M. R., Amar, H., Andrade, D. A., Andreopoulos, C., Ankowski, A. M., Arroyave, M. A., Aushev, V., Ayala-Torres, M. A., Baldi, P., Backhouse, C., Balantekin, A. B., Barkhouse, W. A., Alzas, P. Barham, Barrow, J. L., Battat, J. B. R., Bazetto, M. C. Q., Beacom, J. F., Behera, B., Bellettini, G., Berger, J., Bezerra, A. T., Bian, J., Bilki, B., Bles, B., Bolton, T., Bomben, L., Bonesini, M., Bonilla-Diaz, C., Boran, F., Borkum, A. N., Bostan, N., Brailsford, D., Branca, A., Brunetti, G., Cai, T., Chappell, A., Charitonidis, N., Cintra, P. H. P., Conley, E., Coan, T. E., Cova, P., Cremaldi, L. M., Crespo-Anadon, J. I., Cuesta, C., Dallavalle, R., Davies, G. S., De, S., Neto, P. Dedin, Delgado, M., Delmonte, N., Denton, P. B., De Roeck, A., Dharmapalan, R., Djurcic, Z., Dolek, F., Doran, S., Dorrill, R., Duffy, K. E., Dutta, B., Dvornikov, O., Edayath, S., Evans, J. J., Ezeribe, A. C., Falcone, A., Fani, M., Felix, J.","doi":"10.1088/1361-6471/acad17","DOIUrl":"https://doi.org/10.1088/1361-6471/acad17","url":null,"abstract":"Abstract In this paper, we review scientific opportunities and challenges related to detection and reconstruction of low-energy (less than 100 MeV) signatures in liquid argon time-projection chamber (LArTPC) neutrino detectors. LArTPC neutrino detectors designed for performing precise long-baseline oscillation measurements with GeV-scale accelerator neutrino beams also have unique sensitivity to a range of physics and astrophysics signatures via detection of event features at and below the few tens of MeV range. In addition, low-energy signatures are an integral part of GeV-scale accelerator neutrino interaction final-states, and their reconstruction can enhance the oscillation physics sensitivities of LArTPC experiments. New physics signals from accelerator and natural sources also generate diverse signatures in the low-energy range, and reconstruction of these signatures can increase the breadth of Beyond the Standard Model scenarios accessible in LArTPC-based searches. A variety of experimental and theory-related challenges remain to realizing this full range of potential benefits. Neutrino interaction cross-sections and other nuclear physics processes in argon relevant to sub-hundred-MeV LArTPC signatures are poorly understood, and improved theory and experimental measurements are needed; pion decay-at-rest sources and charged particle and neutron test beams are ideal facilities for improving this understanding. There are specific calibration needs in the low-energy range, as well as specific needs for control and understanding of radiological and cosmogenic backgrounds. Low-energy signatures, whether steady-state or part of a supernova burst or larger GeV-scale event topology, have specific triggering, DAQ and reconstruction requirements that must be addressed outside the scope of conventional GeV-scale data collection and analysis pathways. Novel concepts for future LArTPC technology that enhance low-energy capabilities should also be explored to help address these challenges.","PeriodicalId":16770,"journal":{"name":"Journal of Physics G","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135235752","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}