arXiv subjects
Publications and source records attributed to A. B. Balantekin.
This popular lecture, given in the conference celebrating contributions of Akito Arima to physics on the occasion of his 80th anniversary, outlines the role of nuclear physics in understanding the origin of elements.
These summer school lectures cover the use of algebraic techniques in various subfields of nuclear physics. After a brief description of groups and algebras, concepts of dynamical symmetry, dynamical supersymmetry, and supersymmetric quantum mechanics are introduced. Appropriate tools such as quasiparticles, quasispin, and Bogoliubov transformations are discussed with an emphasis on group theoretical foundations of these tools. To illustrate these concepts three physics applications are worked out in some detail: i) Pairing in nuclear physics; ii) Subbarrier fusion and associated group transformations; and iii) Symmetries of neutrino mass and of a related neutrino many-body problem.
We study the effects of electron screening on nuclear reaction rates occurring during the Big Bang nucleosynthesis epoch. The sensitivity of the predicted elemental abundances on electron screening is studied in details. It is shown that electron screening does not produce noticeable results in the abundances unless the traditional Debye-Hückel model for the treatment of electron screening in stellar environments is enhanced by several orders of magnitude. The present work rules out electron screening as a relevant ingredient to Big Bang nucleosynthesis and ruling out exotic possibilities for the treatment of screening, beyond the mean-field theoretical approach.
Proving the existence of an operator that connects non-perturbed states to perturbed states, an alternative derivation of the Dalgarno-Lewis method is given. To illustrate that the Dalgarno-Lewis method is an apt tool for algebraic Hamiltonians, the method is applied to one class of such systems, namely deep three-dimensional potentials with positive parity.
Tabulated rates for astrophysical photodisintegration reactions make use of Boltzmann statistics for the photons involved as well as the interacting nuclei. Here we derive analytic corrections for the Planck-spectrum quantum statistics of the photon energy distribution. These corrections can be deduced directly from the detailed-balance condition without the assumption of equilibrium as long as the photons are represented by a Planck spectrum. Moreover we show that these corrections affect not only the photodisintegration rates but also modify the conditions of nuclear statistical equilibrium as represented in the Saha equation. We deduce new analytic corrections to the classical Maxwell-Boltzmann statistics which can easily be added to the reverse reaction rates of existing reaction network tabulations. We show that the effects of quantum statistics, though generally quite small, always tend to speed up photodisintegration rates and are largest for nuclei and environments for which Q/kT ~ 1. As an illustration, we examine possible effects of these corrections on the r-process, the rp-process, explosive silicon burning, the $γ$-process and big bang nucleosynthesis. We find that in most cases one is quite justified in neglecting these corrections. The correction is largest for reactions near the drip line for an r-process with very high neutron density, or an rp-process at high-temperature.
Expanding products of invariant functions of a group element as a series in the basis of characters of the irreducible representations of a group is widely used in many areas of physics and related fields. In this contribution a formula to generate such expansions and its various applications are briefly reviewed.
We summarize and critically evaluate the available data on nuclear fusion cross sections important to energy generation in the Sun and other hydrogen-burning stars and to solar neutrino production. Recommended values and uncertainties are provided for key cross sections, and a recommended spectrum is given for 8B solar neutrinos. We also discuss opportunities for further increasing the precision of key rates, including new facilities, new experimental techniques, and improvements in theory. This review, which summarizes the conclusions of a workshop held at the Institute for Nuclear Theory, Seattle, in January 2009, is intended as a 10-year update and supplement to Reviews of Modern Physics 70 (1998) 1265.
Pairing plays a crucial role in nuclear spectra and attempts to describe it has a long history in nuclear physics. The limiting case in which all single particle states are degenerate, but with different s-wave pairing strengths was only recently solved. In this strong coupling limit the nuclear pairing Hamiltonian also exhibits a supersymmetry. Another solution away from those limits, namely two non-degenerate single particle states with different pairing strengths, was also given. In this contribution these developments are summarized and difficulties with possible generalizations to more single particle states and d-wave pairing are discussed.
The third neutrino mixing angle theta13 is the least known one. In this contribution, after a brief discussion of the current efforts to determine the value of this angle better, various astrophysical implications of a non-zero value of theta13 are summarized.
Three facets of symmetries in neutrino physics are briefly reviewed: i) The SO(5) symmetry of the neutrino mass and and its connection to the see-saw mechanism; ii) Flavor SU(N) symmetries of dense, self-interacting neutrino gases in astrophysical settings; iii) The neutrino mixing angle theta13 and possible CP-violation in the neutrino sector.
The heavens are full of neutrinos, but so far we have observed a small subset of those. Performing such observations and analyzing the data from them require a thorough understanding of neutrino interactions. In this short review, the current theoretical status of neutrino cross sections are briefly summarized and novel aspects of neutrino interactions that arise in cosmic sites are discussed.
This document describes the physics potential of a new fixed-target program based on a ~1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.
Capability of medium energy setup of a beta beam experiment to probe new physics contributions to neutrino-W and neutrino-Z couplings are investigated. We employ the effective lagrangian approach of Buchmuller and Wyler and obtain 95% confidence level limits on neutrino couplings to these gauge bosons without assuming the flavor universality of the coupling of neutrinos. We show that a beta beam facility can place 3 to 20 times more restrictive limits than present ones on the deviations from the electron neutrino couplings in the Standard Model.
The NSF has chosen the site for the Deep Underground Science and Engineering Laboratory (DUSEL) to be in Lead, South Dakota. In fact, the state of South Dakota has already stepped up to the plate and contributed its own funding for the proposed lab, see http://www.sanfordlaboratoryathomestake.org/index.html. The final decision by NSF for funding the Initial Suite of Experiments for DUSEL will be made early in 2009. At that time the NSF Science Board must make a decision. Of order 200 experimentalists have already expressed an interest in performing experiments at DUSEL. In order to assess the interest of the theoretical community, the Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University (OSU) organized a 3-day DUSEL Theory Workshop in Columbus, Ohio from April 4 - 6, 2008. The workshop focused on the scientific case for six proposed experiments for DUSEL: long baseline neutrino oscillations, proton decay, dark matter, astrophysical neutrinos, neutrinoless double beta decay and N-Nbar oscillations. The outcome of this workshop is the DUSEL Theory White paper addressing the scientific case at a level which may be useful in the decision making process for policy makers at the NSF and in the U.S. Congress. In order to assess the physics interest in the DUSEL project we have posted the DUSEL Theory White paper on the following CCAPP link http://ccapp.osu.edu/whitepaper.html . Please read the white paper and, if you are interested, use the link to show your support by co-signing the white paper.
We explore the physics potential of NuSOnG experiment to probe new physics contributions to $Wμν_μ$ couplings in inverse muon decay and charged current deep inelastic scattering processes. We show that NuSOnG provides two order of magnitude improvement in $Wμν_μ$ compared to LEP bound at 95% C.L.. Combining the results presented here with our earlier results, we obtain a significant improvement in the limits on neutrino flavor universality violation in neutrino-W and neutrino-Z couplings.
We investigate the physics potential of NuSOnG experiment to probe new physics contributions to Z-neutrino-neutrino couplings in muon-neutrino electron elastic and neutral-current deep-inelastic scattering processes. We employ an effective Lagrangian approach and do not a priori assume universality of the coupling of neutrinos to Z. We obtain 95% C.L. limits on possible universality violating couplings.
A simple model of nucleons coupled to angular momentum zero (s-pairs) occupying the valance shell of a semi-magic nuclei is considered. The model has a separable, orbit dependent pairing interaction which dominates over the kinetic term. It is shown that such an interaction leads to an exactly solvable model whose (0+) eigenstates and energies can be computed very easily with the help of the algebraic Bethe ansatz method. It is also shown that the model has a supersymmetry which connects the spectra of some semimagic nuclei. The results obtained from this model for the semimagic Ni isotopes from 58Ni to 68Ni are given. In addition, a new and easier technique for calculating the energy eigenvalues from the Bethe ansatz equations is also presented.
When solar neutrino and KamLAND data are analyzed separately one finds that, even though allowed regions of neutrino parameters overlap, the values of $δm^2$ and the mixing angle $θ_{12}$ at the $χ^2$ minima are different. We show that a non-zero, but small value of the angle $θ_{13}$ can account for this behavior. From the joint analysis of solar neutrino and KamLAND data we find the best fit value of $\sin^2 2 θ_{13} = 0.01 ^{-0.01}_{+0.09}$.