Authors:A S Parvan First page: 125002 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 the 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. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-01T00:00:00Z DOI: 10.1088/1361-6471/acfe23 Issue No:Vol. 50, No. 12 (2023)

Authors:Gustavo Rigolin First page: 125003 Abstract: We derive a Dirac-like equation, the asymmetric Dirac equation, where particles and antiparticles sharing the same wave number have different energies and momenta. We show that this equation is Lorentz covariant under proper Lorentz transformations (boosts and spatial rotations) and also determine the corresponding transformation law for its wave function. We obtain a formal connection between the asymmetric Dirac equation and the standard Dirac equation and we show that by properly adjusting the free parameters of the present wave equation we can make it reproduce the predictions of the usual Dirac equation. We show that the rest mass of a particle in the theoretical framework of the asymmetric Dirac equation is a function of a set of four parameters, which are relativistic invariants under proper Lorentz transformations. These four parameters are the analog to the mass that appears in the standard Dirac equation. We prove that in order to guarantee the covariance of the asymmetric Dirac equation under parity and time reversal operations (improper Lorentz transformations) as well as under the charge conjugation operation, these four parameters change sign in exactly the same way as the four components of a four-vector. The mass, though, being a function of the square of those parameters remains an invariant. We also extensively study the free particle plane wave solutions to the asymmetric Dirac equation and derive its energy, helicity, and spin projection operators as well as several Gordon’s identities. The hydrogen atom is solved in the present context after applying the minimal coupling prescription to the asymmetric Dirac equation, which also allows us to appropriately obtain its non-relativistic limit. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-24T00:00:00Z DOI: 10.1088/1361-6471/ad0312 Issue No:Vol. 50, No. 12 (2023)

Authors:A B Arbuzov; U E Voznaya First page: 125004 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 }^{3}{L}^{2}) are calculated analytically, where L=\mathrm{ln}({\mu }_{F}^{2}{/m}_{e}^{2}) is the large logarithm which depends on the factorization energy scale μF ≫ me. The results are process independent and relevant for future high-precision experiments. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-06T00:00:00Z DOI: 10.1088/1361-6471/acff7b Issue No:Vol. 50, No. 12 (2023)

Authors:Gustavo Rigolin First page: 125005 Abstract: We build the fully relativistic quantum field theory related to the asymmetric Dirac fields first presented in a prequel to this work. These fields are solutions of the asymmetric Dirac equation, a Lorentz covariant Dirac-like equation whose positive and ‘negative’ frequency plane wave solutions’ dispersion relations are no longer degenerate. At the second quantization level, we show that this implies that particles and antiparticles sharing the same wave number have different energies and momenta. In spite of that, we prove that by properly fixing the values of the relativistic invariants that define the asymmetric Dirac free field Lagrangian density, we can build a consistent, fully relativistic, and renormalizable quantum electrodynamics (QED) that is empirically equivalent to the standard QED. We discuss the reasons and implications of this non-trivial equivalence, exploring qualitatively other scenarios in which the asymmetric Dirac fields may lead to beyond the standard model predictions. We give a complete account of how the asymmetric Dirac fields and the corresponding annihilation and creation operators transform under improper Lorentz transformations (parity and time reversal operations) and under the charge conjugation operation. We also prove that the present theory respects the CPT theorem. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-24T00:00:00Z DOI: 10.1088/1361-6471/ad0313 Issue No:Vol. 50, No. 12 (2023)

Authors:Ying Zhang First page: 125006 Abstract: A flavor structure with minimal parameters is proposed to address the fermion mass hierarchy and flavor mixing for quarks and leptons. Yukawa interaction is reconstructed in a new basis to show a common flat structure for up-type quarks, down-type quarks, charged leptons, and Dirac neutrinos. A {SO}(2{)}_{{LR}}^{f} flavor symmetry is found from the hierarchy masses of quarks and leptons, which dominated Cabibbo–Kobayashi–Maskawa (CKM) mixing for quarks and Pontecorvo–Maki–Nakagawa–Sakata mixing for leptons. It results that the minimal flavor structure successfully addresses flavor mixings of quarks and leptons even in the mass hierarchy limit, which means that mass hierarchy and flavor mixing are two independent questions. As a prediction, a sum rule on the mixing angles and CP violation phase (CPV) is suggested, which explains the smallness of s13 as a natural result of the mass hierarchy. Generalizing the flat structure to quarks and leptons, a unified Yukawa interaction is also achieved for all fermions with only a single coupling. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-15T00:00:00Z DOI: 10.1088/1361-6471/ad074d Issue No:Vol. 50, No. 12 (2023)

Authors:Nobuhito Maru; Haruki Takahashi Yoshiki Yatagai First page: 125007 Abstract: Grand gauge–Higgs unification of five-dimensional SU(6) gauge theory on an orbifold S1/Z2 with localized gauge kinetic terms is discussed. The Standard Model (SM) fermions on the boundaries and some massive bulk fermions coupling to the SM fermions are introduced. Compared to the previous model, the number of bulk fermions is reduced, which reproduces the generation mixing of SM fermions and SM fermion mass hierarchy by mildly tuning the bulk masses and parameters of the localized gauge kinetic terms. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-16T00:00:00Z DOI: 10.1088/1361-6471/ad05d9 Issue No:Vol. 50, No. 12 (2023)

Authors:Johan Löfgren First page: 125008 Abstract: I argue that the consistency of any resummation method can be established if the method follows a power counting derived from a hierarchy of scales. I.e. whether it encodes a top-down effective field theory. This resolves much confusion over which resummation method to use once an approximation scheme is settled on. And if no hierarchy of scales exists, you should be wary about resumming. I give evidence from the study of phase transitions in thermal field theory, where adopting a consistent power-counting scheme and performing a strict perturbative expansion dissolves many common problems of such studies: gauge dependence, strong renormalization scale dependence, the Goldstone boson catastrophe, IR divergences, imaginary potentials, mirages (illusory barriers), perturbative breakdown, and linear terms. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-15T00:00:00Z DOI: 10.1088/1361-6471/ad074b Issue No:Vol. 50, No. 12 (2023)

Authors:J R Alvarado García; D Rosales Herrera, P Fierro, J E Ramírez, A Fernández Téllez C Pajares First page: 125105 Abstract: In color string models, the transverse momentum distribution (TMD) is obtained through the convolution of the Schwinger mechanism with the string tension fluctuations distribution. Considering a q-Gaussian distribution for these fluctuations, the TMD becomes a hypergeometric confluent function that adequately reproduces the characteristic scales at low and high pT values. In this approach, the hard scale of the TMD is a consequence of considering a heavy-tailed distribution for the string tension fluctuations whose width rises as \sqrt{s}, multiplicity or centrality increases. In this paper, we introduce broader information of the TMD in the color string percolation model by determining the color suppression factor, which now also depends on the parameters of the q-Gaussian. To this end, we analyze the reported data on pp and AA collisions at different center of mass energies, multiplicities, and centralities. In particular, for minimum bias pp collisions, we found that the q-Gaussian parameters and the effective temperature are monotonically increasing functions of the center of mass energy. Similar results are found for AA collisions as a function of the centrality at fixed \sqrt{s}. We summarize these results in a phase diagram that indicates the q-Gaussian parameters region allowing the quark–gluon plasma formation. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-06T00:00:00Z DOI: 10.1088/1361-6471/acffe1 Issue No:Vol. 50, No. 12 (2023)

Authors:Waseem Bhat; M Farooq Mir, Vipul Bairathi, Towseef Bhat, Sonia Kabana Shabir Bhat First page: 125106 Abstract: Elliptic flow (v2) of inclusive charged hadrons at mid-rapidity (∣η∣ < 1.0) in Au+Au collisions at Elab = 35 A GeV using the parton hadron string dynamics (PHSD) model are presented as a function of centrality, transverse momentum (pT) and pseudo-rapidity (η). The v2 results are obtained using the η-sub event plane method with respect to the event plane angle (ψ2) and participant plane angle ({\psi }_{2}^{{PP}}). pT-integrated charged hadron v2 shows a strong centrality dependence in Au+Au collisions at Elab = 35 A GeV. The eccentricity-scaled elliptic flow (v2/ε2) also shows centrality dependence. The higher values of v2/ε2 in central collisions suggest the development of stronger collectivity. The calculations are compared with the results from Au+Au collisions at \sqrt{{s}_{\mathrm{NN}}}=7.7\,\mathrm{GeV} published by the STAR experiment at RHIC. We also compare the results of HSD and PHSD modes to investigate the contribution of hadronic and partonic phases of the medium on the calculated v2. The current results serve as a prediction of the collective behavior of the matter produced in baryon-rich and moderate temperature conditions for the upcoming multi-purpose detector at the nuclotron-based Ion collider facility (NICA) and compressed baryonic matter experiment at the facility for antiproton and ion research. These predictions are also useful for interpreting data measured at relativistic heavy ion collider (RHIC) beam energy scan program. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-08T00:00:00Z DOI: 10.1088/1361-6471/ad0418 Issue No:Vol. 50, No. 12 (2023)

Authors:Mahima Upadhyay; Mahesh Choudhary, Namrata Singh, A Gandhi, Aman Sharma, Sumit Bamal, Akash Hingu, S Mukherjee, G Mishra, Sukanya De, L S Danu, Saurav Sood, Sajin Prasad, Ajay Kumar, R G Thomas A Kumar First page: 125107 Abstract: In the present work, we have measured 98Mo(n,γ)99Mo reaction cross-section using a 7Li(p,n)7Be neutron source at 1.67 ± 0.14, 2.06 ± 0.14 and 2.66 ± 0.16 MeV neutron energies. We have employed offline γ-ray spectroscopy to measure the induced activity of the sample. The 115In(n,n’γ)115mIn reaction was used as a monitor reaction. Different attributes propagating the uncertainty in the total result, measured cross-sections with their uncertainties and correlation coefficients are given in detail in the present study. The result is compared with the data libraries, EXFOR database and theoretical model outcome from different level density models. Citation: Journal of Physics G: Nuclear and Particle Physics PubDate: 2023-11-08T00:00:00Z DOI: 10.1088/1361-6471/ad0417 Issue No:Vol. 50, No. 12 (2023)