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Title: Not-so-well-tempered neutralino

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 5; Related Information: CHORUS Timestamp: 2017-09-15 10:59:49; Journal ID: ISSN 2470-0010
American Physical Society
Country of Publication:
United States

Citation Formats

Profumo, Stefano, Stefaniak, Tim, and Stephenson-Haskins, Laurel. Not-so-well-tempered neutralino. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.96.055018.
Profumo, Stefano, Stefaniak, Tim, & Stephenson-Haskins, Laurel. Not-so-well-tempered neutralino. United States. doi:10.1103/PhysRevD.96.055018.
Profumo, Stefano, Stefaniak, Tim, and Stephenson-Haskins, Laurel. 2017. "Not-so-well-tempered neutralino". United States. doi:10.1103/PhysRevD.96.055018.
title = {Not-so-well-tempered neutralino},
author = {Profumo, Stefano and Stefaniak, Tim and Stephenson-Haskins, Laurel},
abstractNote = {},
doi = {10.1103/PhysRevD.96.055018},
journal = {Physical Review D},
number = 5,
volume = 96,
place = {United States},
year = 2017,
month = 9

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on September 15, 2018
Publisher's Accepted Manuscript

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  • Exponent parameters of the nonrelativistically optimized well-tempered Gaussian basis sets of Huzinaga and Klobukowski have been employed for Dirac--Fock--Roothaan calculations without their reoptimization. For light atoms He (atomic number {ital Z}=2)--Rh ({ital Z}=45), the number of exponent parameters used has been the same as the nonrelativistic basis sets and for heavier atoms Pd ({ital Z}=46)--Hg({ital Z}=80), two 2{ital p} (and three 3{ital d}) Gaussian basis functions have been augmented. The scheme of kinetic energy balance and the uniformly charged sphere model of atomic nuclei have been adopted. The qualities of the calculated basis sets are close to the Dirac--Fock limit.
  • A systematic calculation of new relativistic Gaussian basis sets is reported. The new basis sets are similar to the previously reported ones (J. Chem. Phys. {bold 91}, 4193 (1989)), but, in the calculation, the Breit interaction has been explicitly included besides the Dirac--Coulomb Hamiltonian. They have been adopted for the calculation of the self-consistent field effect on the Breit interaction energies and are expected to be useful for the studies on higher-order effects such as the electron correlations and other quantum electrodynamical effects.
  • The prospects are examined for the detection of a slow decay of the lightest neutralino (or any other long-lived particles) at the CERN LHC and at the Very Large Hadron Collider (VLHC). We first point out that such hadron colliders will become the {open_quotes}neutralino factory{close_quotes} producing 10{sup 6}{endash}10{sup 9}neutralinos/yr, if gluinos and/or squarks actually exist below O(1) TeV. The lightest neutralino ({tilde {chi}}{sub 1}{sup 0}), usually assumed to be stable, will be unstable if lighter superparticles such as the gravitino ({tilde G}) or axino ({tilde a}) exist, or R-parity is not conserved. The decay signal would, however, be missed inmore » usual collider experiments, particularly when the decay mostly occurs outside the detector. In order to search for such a slow decay of {tilde {chi}}{sub 1}{sup 0}, we propose a dedicated experiment where the collision products are dumped by a thick shield, which is followed by a long decay tunnel. The decay product of {tilde {chi}}{sub 1}{sup 0} can be detected by a detector located at the end of the tunnel. The slow arrival time and the large off angle (to the direction of the interaction point) of the decay product will provide a clear signature of slowly decaying {tilde {chi}}{sub 1}{sup 0}{close_quote}s. One can explore the decay length (c{tau}) in a wide range, i.e., 0.2 m to 1{times}10{sup 5}km for m{sub {tilde {chi}}{sub 1}{sup 0}}=25GeV and 1 m to 2 km for m{sub {tilde {chi}}{sub 1}{sup 0}}=200GeV at the LHC. This corresponds to the range of the SUSY breaking scale {radical} (F) =2{times}10{sup 5} to 2{times}10{sup 7}GeV in case of the {tilde {chi}}{sub 1}{sup 0}{r_arrow}{gamma}{tilde G} decay predicted in gauge-mediated SUSY breaking models. At VLHC, one can extend the explorable range of m{sub {tilde {chi}}{sub 1}{sup 0}} up to {approximately}1000GeV, and that of {radical} (F) up to {approximately}1{times}10{sup 8}GeV. In the case of the {tilde {chi}}{sub 1}{sup 0}{r_arrow}{gamma}{tilde a} decay, the Peccei-Quinn symmetry breaking scale F{sub a} can be explored up to {approximately}5{times}10{sup 11}GeV. The mass of the decaying particle can be determined by using the correlation between the energy and the arrival time of the decay product. With the setup we propose, one can also search for (i) other decay modes of {tilde {chi}}{sub 1}{sup 0} such as the R-parity violating one, (ii) slow decays of any other long-lived neutral or charged particles, and (iii) heavy stable charged particles. {copyright} {ital 1997} {ital The American Physical Society}« less
  • We present exact analytic cross sections for all neutralino-neutralino coannihilations into two-body tree level final states. These expressions allow the calculation of important contributions to the neutralino relic abundance over large regions of mSUGRA parameter space and are particularly useful in theories with non-universal gaugino masses.