17525841
Probing supergravity grand unification in the Brookhaven g-2 experiment.
A quantitative analysis of ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}$\ensuremath{\equiv}1/2(g-2${)}_{\mathrm{\ensuremath{\mu}}}$ within the framework of supergravity grand unification and radiative breaking of the electroweak symmetry is given. It is found that ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}^{\mathrm{SUSY}}$ is dominated by the chiral interference term from the light chargino exchange, and that this term carries a signature which correlates strongly with the sign of \ensuremath{\mu}. Thus as a rule ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}^{\mathrm{SUSY}}$g0 for \ensuremath{\mu}g0 and ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}^{\mathrm{SUSY}}$0 for \ensuremath{\mu}0 with very few exceptions when tan\ensuremath{\beta}\ensuremath{\sim}1. At the quantitative level it is shown that if the E821 BNL experiment can reach the expected sensitivity of 4\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ and there is a reduction in the hadronic error by a factor of 4 or more, then the experiment will explore a majority of the parameter space in the ${\mathit{m}}_{0}$-${\mathit{m}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$ plane in the region ${\mathit{m}}_{0}$\ensuremath{\lesssim}400 GeV, ${\mathit{m}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$\ensuremath{\lesssim}700 GeV for tan\ensuremath{\beta}\ensuremath{\gtrsim}10 assuming the experiment will not discard the standard model result within its 2\ensuremath{\sigma} uncertainty limit. For smaller tan\ensuremath{\beta}, the SUSY reach of E821 will still be considerable. Further, if no effect within the 2\ensuremath{\sigma} limit of the standard model value is seen, then large tan\ensuremath{\beta} scenarios will be severely constrained within the current naturalness criterion, i.e., ${\mathit{m}}_{0}$,${\mathit{m}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$\ensuremath{\lesssim}1 TeV. \textcopyright{} 1996 The American Physical Society.
8573164
Naturalness, weak scale supersymmetry, and the prospect for the observation of supersymmetry at the Fermilab Tevatron and at the CERN LHC
Naturalness bounds on weak scale supersymmetry in the context of radiative breaking of the electroweak symmetry are analyzed. In the case of minimal supergravity it is found that for low $\mathrm{tan}\ensuremath{\beta}$ and for low values of fine-tuning $\ensuremath{\Phi},$ where $\ensuremath{\Phi}$ is defined essentially by the ratio ${\ensuremath{\mu}}^{2}{/M}_{Z}^{2}$ where $\ensuremath{\mu}$ is the Higgs mixing parameter and ${M}_{Z}$ is the $Z$ boson mass, the allowed values of the universal scalar parameter ${m}_{0},$ and the universal gaugino mass ${m}_{1/2}$ lie on the surface of an ellipsoid with radii fixed by $\ensuremath{\Phi}$ leading to tightly constrained upper bounds $\ensuremath{\sim}\sqrt{\ensuremath{\Phi}}.$ Thus for $\mathrm{tan}\ensuremath{\beta}l~2(l~5)$ it is found that the upper limits for the entire set of sparticle masses lie in the range $l700 \mathrm{GeV} (l1.5 \mathrm{TeV})$ for any reasonable range of fine-tuning $(\ensuremath{\Phi}l~20).$ However, it is found that there exist regions of the parameter space where the fine-tuning does not tightly constrain ${m}_{0}$ and ${m}_{1/2}.$ Effects of nonuniversalities in the Higgs boson sector and in the third generation sector on naturalness bounds are also analyzed and it is found that nonuniversalities can significantly affect the upper bounds. It is also found that achieving the maximum Higgs boson mass allowed in supergravity unified models requires a high degree of fine-tuning. Thus a heavy sparticle spectrum is indicated if the Higgs boson mass exceeds 120 GeV. The prospect for the discovery of supersymmetry at the Fermilab Tevatron and at the CERN LHC in view of these results is discussed.
15133750
LHC signature of the minimal SUGRA model with a large soft scalar mass
Abstract Thanks to the focus point phenomenon, it is quite natural for the minimal SUGRA model to have a large soft scalar mass ( m 0 >1 TeV). A distinctive feature of this model is an inverted hierarchy, where the lighter stop has a significantly smaller mass than the other squarks and sleptons. Consequently, the gluino is predicted to decay dominantly via stop exchange into a channel containing 2 b and 2 W along with the LSP. We exploit this feature to construct a robust signature for this model at the LHC in leptonic channels with 3–4 b tags and a large missing- E T .
10436358
Nonuniversal scalar mass scenario with Higgs funnel region of supersymmetric dark matter: A signal-based analysis for the Large Hadron Collider
We perform a multilepton channel analysis in the context of the Large Hadron Collider (LHC) for Wilkinson Microwave Anisotropy probe (WMAP) compatible points in a model with non-universal scalar masses, which admits a Higgs funnel region of supersymmetry dark matter even for a small tan�. In addition to two and threelepton final states, four-lepton events, too, are shown to be useful for this purpose. We also compare the collider signatures in similar channels for WMAP compatible points in the minimal supergravity (mSUGRA) framework with similar gluino masses. Some definite features of such non-universal scenario emerge from the analysis.
6131379
Constraints on explicit CP violation from the Brookhaven muon g − 2 experiment
We use the recently derived CP phase dependent analytic results for the supersymmetric electroweak correction to g{sub {mu}}{minus}2 to constrain the explicit CP phases in softly broken supersymmetry using the new physics effect seen in the g{minus}2 Brookhaven measurement. It is shown that the BNL data strongly constrain the CP violating phase {theta}{sub {mu}} (the phase of the Higgs mixing parameter {mu}) and {xi}{sub 2} [the phase of the SU(2) gaugino mass {tilde m}{sub 2}] and as much as 60{endash}90% of the region in the {xi}{sub 2}{minus}{theta}{sub {mu}} plane is eliminated over a significant region of the MSSM parameter space by the BNL constraint. The region of CP phases not excluded by the BNL experiment allows for large phases and for a satisfaction of the EDM constraints via the cancellation mechanism. We find several models with large CP violation which satisfy the EDM constraint via the cancellation mechanism and produce an a{sub {mu}}{sup SUSY} consistent with the new physics signal seen by the Brookhaven experiment. The sparticle spectrum of these models lies within reach of the planned accelerator experiments.
15823868
Higgsino dark matter in a SUGRA model with nonuniversal gaugino masses
We study a specific SUGRA model with nonuniversal gaugino masses as an alternative to the minimal SUGRA model in the context of supersymmetric dark matter. The lightest supersymmetric particle in this model turns out to be a Higgsino-dominated instead of a B-ino-dominated lightest neutralino. The thermal relic density of this Higgsino dark matter is somewhat lower than the cosmologically favored range, which means that it may be only a subdominant component of cold dark matter. Nonetheless, it predicts favorable rates of indirect detection, which can be seen in square-km-size neutrino telescopes.
31869814
Heat partition in damped reactions.
The effect of driving force on the division of excitation energy between the asymmetric colliding partners in deep inelastic heavy-ion collisions is studied in the nucleon-exchange model. For this purpose an event-by-event analysis using Monte Carlo simulation technique is performed. It is seen that the fraction of the total excitation energy carried by the projectile-like fragment is sensitive to the mass drift. The model is also applied to analyze the correlation between fragment mass and excitation energy for a given total energy loss and significant correlation is found. The reactions induced by {sup 56}Fe at 9 MeV/nucleon and {sup 74}Ge at 8.5 MeV/nucleon on {sup 165}Ho are considered in our analysis and the calculated correlations are in good agreement with the results obtained from the kinematic coincidence experiments.