Article
Physics, Particles & Fields
P. Abolhadi, M. M. Yazdanpanah, H. Nematollahi
Summary: We investigate the unpolarized transverse momentum dependent (TMD) structure of light mesons at low Q^2 scales in the nonperturbative region of quantum chromodynamics (QCD). We calculate the unpolarized TMD valence quark distribution functions of pion and kaon using the covariant parton model, taking into account the flavor-dependent covariant momentum distribution of quarks. We apply a statistical model to this momentum distribution for the first time and consider the quarks to have mass. The results of the TMD valence distributions of light mesons exhibit convenient general properties. We also obtain the integrated valence quark distributions of pion and kaon and compare our results with those of other models.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Nuclear
Chun-Xuan Wang, Li-Sheng Geng, Bingwei Long
Summary: This work investigates the renormalization group invariance of covariant power counting in nucleon-nucleon scattering, finding it satisfied in certain channels. The correlation between S-1(0) and P-3(1) channels is noted, and by fitting relevant low energy constants, the P-3(1) phase shifts can be described relatively well. Renormalization group invariance is also confirmed in the P-1(1) and S-3(1) - D-3(1) channels.
Article
Astronomy & Astrophysics
Dongyan Fu, Bao-Dong Sun, Yubing Dong
Summary: In this work, the electromagnetic and gravitational form factors of a spin-3/2 particle, ?? resonance, are simultaneously calculated using a relativistic covariant quark-diquark approach. The obtained form factors are in good agreement with experimental data and comparable to other methods. Additionally, the gravitational form factors giving mechanical properties of the ?? isobar are provided, along with discussions on the sign and interpretation of the D term.
Article
Astronomy & Astrophysics
M. C. Gordillo, F. De Soto, J. Segovia
Summary: The LHCb collaboration has found that the production rate of X(3872) decreases as final state particle multiplicity increases in proton-proton collisions. The ALICE experiment at CERN has observed that the number of deuterons produced increases with multiplicity. Researchers have used a diffusion Monte Carlo method to analyze the structure of X(3872) and found that it resembles a light-meson-heavy-meson molecule. They have also computed the mass of the first color excited cc over bar qq over bar tetraquark state and found it to be around 4.0 GeV, a region where many new exotic candidates have been collected.
Article
Multidisciplinary Sciences
B. Behzadmoghaddam, M. Radin, S. Bayegan
Summary: In this paper, the chiral effective field theory is used to study the spin singlet channel S-1(0) of proton-proton scattering, adopting a new suggested power counting. The pp zero scattering amplitude is reproduced by including one pion exchange at leading order (LO) and the Coulomb interaction between protons at next-to-leading order (NLO). This provides a systematic improvement up to NLO compared to the result obtained from the Nijm93 potential model.
SCIENTIFIC REPORTS
(2023)
Article
Astronomy & Astrophysics
S. Dubnicka, A. Z. Dubnickova, M. A. Ivanov, A. Liptaj
Summary: Decay processes B -> D-(s)(()*())h (h = pi, rho) are investigated using the confined covariant quark model with the assumption of naive factorization. The theoretical results consistently overestimate the experimental branching fractions, similar to observations made by other authors.
Article
Physics, Multidisciplinary
Andrei B. Klimov, Ulrich Seyfarth, Hubert de Guise, Luis L. Sanchez-Soto
Summary: A practical recipe is proposed to compute s-parametrized maps for systems with SU(1, 1) symmetry, establishing equivalence relations between them by connecting Q- and P-symbols through an operator invariant under the group. The specific case of self-dual (Wigner) phase-space functions defined on the upper sheet of the two-sheet hyperboloid (or inside the Poincare disc) is analyzed.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Astronomy & Astrophysics
Seong Youl Choi, Jae Hoon Jeong
Summary: An algorithm is developed to efficiently construct the Lorentz covariant effective three-point vertices for particle decay into two daughter particles, with arbitrary masses and spins for the three particles. The algorithm utilizes the closely related correspondence between the helicity formalism and the covariant formulation for counting independent terms and identifying basic covariant three-point vertices. Assembling the basic operators according to the algorithm allows for systematic construction of all covariant three-point vertices.
Article
Astronomy & Astrophysics
Seong Youl Choi, Jae Hoon Jeong
Summary: An efficient algorithm has been developed for compactly weaving all Lorentz-covariant three-point vertices related to the decay of a massive particle X into two particles M-1, M-2 with equal mass and spin. Utilizing the equivalence between the helicity formalism and covariant formulation, basic building blocks for constructing each helicity combination's covariant three-point vertex have been identified. The algorithm's power is demonstrated through several typical examples with specific J and s values.
Article
Physics, Particles & Fields
Zhi-Jie Sun, Si-Yang Wang, Zhi-Qing Zhang, You-Ya Yang, Zi-Yu Zhang
Summary: In this study, we investigate the semileptonic decays of Bc meson using the framework of covariant light-front quark model. The results can be used to test lepton flavor universality and provide insights into the RJ/Psi anomaly.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Jin-Li Zhang, Guang-Zhen Kang, Jia-Lun Ping
Summary: In this paper, the generalized parton distributions of both unpolarized and polarized rho meson are studied in the Nambu-Jona-Lasinio model using the proper time regularization scheme. The symmetry properties of the rho meson generalized parton distributions are checked. The obtained distribution functions and form factors satisfy the required properties. The impact parameter dependent parton distribution functions are also studied.
Article
Physics, Nuclear
Zhi-Wei Liu, Jing Song, Kai-Wen Li, Li-Sheng Geng
Summary: By fitting to hyperon-nucleon scattering data, the S = -3 and -4 baryon-baryon interactions are derived, with consideration for SU(3) flavor symmetry-breaking effects. The predicted phase shifts for certain channels are in qualitative agreement with lattice QCD data, while further validation is needed for the S = -4 channel.
Article
Astronomy & Astrophysics
Laxmipriya Pati, Daniel Blixt, Maria-Jose Guzman
Summary: We present Hamilton's equations for the teleparallel equivalent of general relativity (TEGR), a reformulation of general relativity based on a curvatureless, metric compatible, and torsionful connection. The Hamiltonian for TEGR is obtained through the decomposition of phase space variables and is presented in the covariant formalism for the first time. Mathematical formalism is introduced to compute Hamilton's equations in both Weitzenbock gauge and covariant formulation, requiring the introduction of new fields. We also derive explicit relations between conjugate momenta of the tetrad and the metric in GR.
Article
Physics, Nuclear
J. Rijneveen, N. Rijneveen, H. Krebs, A. M. Gasparyan, E. Epelbaum
Summary: In this study, radiative pion photoproduction was calculated within the framework of covariant chiral perturbation theory with explicit Delta(1232) degrees of freedom. The analysis included contributions up to next-to-next-to-leading order, with the extraction of the Delta(+) magnetic moment from experimental data and estimation of errors from truncation using Bayesian approach. Comparisons were made with previous studies within the delta-expansion scheme and Delta-less theory, showing differences in results under the small-scale expansion adjusted for the Delta region.
Article
Physics, Nuclear
A. Martinez Torres, K. P. Khemchandani, E. Oset
Summary: We have conducted a theoretical study on the gamma d -> pi(0)eta d reaction using a realistic model for the gamma N -> pi(0)eta N reaction. We found the rescattering of the pions and the eta on a different nucleon to be an important mechanism in sharing the momentum transfer of the reaction between two nucleons. Other contributions involving the gamma N -> pi(+/-)pi N-0' process have also been considered. The dynamics of our model provide a natural explanation for the shift of the eta-d and pi(0)-d mass distributions compared to a phase space calculation.
Article
Physics, Particles & Fields
Sofia Leitao, Yang Li, Pieter Maris, M. T. Pena, Alfred Stadler, James P. Vary, Elmar P. Biernat
EUROPEAN PHYSICAL JOURNAL C
(2017)
Article
Physics, Multidisciplinary
M. T. Pena, Alfred Stadler
Article
Physics, Multidisciplinary
Sofia Leitao, Alfred Stadler, M. T. Pena, Elmar P. Biernat
Article
Astronomy & Astrophysics
Sofia Leitao, Alfred Stadler, M. T. Pena, Elmar P. Biernat
Article
Physics, Multidisciplinary
Alfred Stadler, Sofia Leitao, M. T. Pena, Elmar P. Biernat
Article
Physics, Multidisciplinary
Elmar P. Biernat, Franz Gross, Teresa Pena, Alfred Stadler, Sofia Leitao
Article
Instruments & Instrumentation
Nicolo Tuccori, Teresa Pinheiro, Teresa Pena, Luis C. Alves, Maria Joao Botelho, Joana Raimundo, Carlos Vale
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2019)
Article
Astronomy & Astrophysics
G. Ramalho, M. T. Pena
Article
Astronomy & Astrophysics
G. Ramalho, M. T. Pena, K. Tsushima
Article
Astronomy & Astrophysics
Gernot Eichmann, Pedro Duarte, M. T. Pena, Alfred Stadler
Article
Astronomy & Astrophysics
Elmar P. Biernat, Franz Gross, M. T. Pena, Alfred Stadler, Sofia Leitao
Article
Astronomy & Astrophysics
Sofia Leitao, Alfred Stadler, M. T. Pena, Elmar P. Biernat
Article
Astronomy & Astrophysics
G. Ramalho, M. T. Pena
Proceedings Paper
Physics, Applied
Elmar P. Biernat, M. T. Pena, J. E. Ribeiro, Alfred Stadler, Franz Gross
XITH CONFERENCE ON QUARK CONFINEMENT AND HADRON SPECTRUM
(2016)
Article
Astronomy & Astrophysics
G. Ramalho, M. T. Pena, J. Weil, H. van Hees, U. Mosel