Jet production in deep inelastic scattering for 120 <
Q
2 < 3600 GeV
2 has been studied using data from an integrated luminosity of 3.2 pb
−1 collected with the ZEUS detector at HERA. Jets are ...identified with the JADE algorithm. A cut on the angular distribution of parton emission in the
γ
∗-
parton
centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to
O
(
α
s
2) perturbative QCD calculations, allow a precise determination of
α
s
(
Q
) in three
Q
2-intervals. The values are consistent with a running of
ifα
s
(
Q
), as expected from QCD. Extrapolating to
Q
= M
Z
0
α
s
(
M
Z
0
) = 0.117 ± 0.005 (stat)
−0.005
+0.004 (syst
exp) ± 0.007 (syst
theory).
Full text
Available for:
IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Phys.Rev.D52:4178-4182,1995 We propose a string-derived model based on the gauge group $SU(5)\times U(1)$
which satisfies the stringent constraints from no-scale supergravity, allows
gauge coupling ...unification at the string scale, and entails previously
unexplored correlations among various sectors of the model. All supersymmetric
observables are given in terms of a single mass parameter with self-consistency
of the model determining the rest, including $\tan\beta=2.2-2.3$ and
$m_t\approx175\GeV$. A small non-universality of the scalar masses at the
string scale produces a downward shift in the right-handed slepton masses at
the electroweak scale, such that for $m_{1/2}\gsim180\GeV$ these particles
become lighter than the lightest neutralino. This cutoff in the parameter space
entails the imminent discovery of charginos at the Tevatron via trilepton
events ($m_{\chi^\pm_1}<90\GeV$). Also, the lightest Higgs boson
($m_h<90\GeV$), the lightest chargino, and the right-handed sleptons
($m_{\tilde\ell_R}<50\GeV$) should be readily observable at LEPII. We also
discuss the model predictions for $B(b\to s\gamma)$, $(g-2)_\mu$, $R_b$, and
the prospects for direct neutralino dark matter detection.
Int.J.Mod.Phys.A10:4241-4264,1995 We consider the experimental predictions of two {\em one-parameter} no-scale
$SU(5)\times U(1)$ supergravity models with string-inspired moduli and dilaton
seeds of ...supersymmetry breaking. These predictions have been considerably
sharpened with the new information on the top-quark mass from the Tevatron, and
the actual measurement of the $B(b\to s\gamma)$ branching ratio from CLEO. In
particular, the sign of the Higgs mixing parameter $\mu$ is fixed. A more
precise measurement of the top-quark mass above (below) $\approx160\GeV$ would
disfavor the dilaton (moduli) scenario. Similarly a measurement of the lightest
Higgs-boson mass above 90 GeV (below 100 GeV) would disfavor the dilaton
(moduli) scenario. At the Tevatron with $100\ipb$, the reach into parameter
space is significant only in the dilaton scenario ($m_{\chi^\pm_1}\lsim80\GeV$)
via the trilepton and top-squark signals. At LEPII the dilaton scenario could
be probed up the kinematical limit via chargino and top-squark pair production,
and the discovery of the lightest Higgs boson is guaranteed. In the moduli
scenario only selectron pair production looks promising. We also calculate the
supersymmetric contribution to the anomalous magnetic moment of the muon.
Mod.Phys.Lett.A10:2289-2296,1995 An interesting prediction of a string-inspired {\em one-parameter}
$SU(5)\times U(1)$ supergravity model, is the fact that the lightest member
($\tilde t_1$) of the ...top-squark doublet $(\tilde t_1,\tilde t_2)$, may be
substantially lighter than the top quark. This sparticle ($\tilde t_1$) may be
readily pair-produced at the Tevatron and, if $m_{\tilde t_1}\lsim130\GeV$,
even be observed at the end of Run IB. Top-squark production may also be an
important source of sought-for top-quark signatures in the dilepton and
$\ell$+jets channels. Therefore, a re-analysis of the top data sample in the
presence of a possibly light top-squark appears necessary before definitive
statements concerning the discovery of the top quark can be made. Such a light
top-squark is linked with a light supersymmetric spectrum, which can certainly
be searched for at the Tevatron through trilepton and squark-gluino searches,
and at LEPII through direct $\tilde t_1$ pair-production (for $m_{\tilde
t_1}\lsim100\GeV$) and via chargino and Higgs-boson searches.
Prog.Part.Nucl.Phys.33:303-395,1994 Review to appear in Progress in Particle and Nuclear Physics. Contents:
{1}Introduction}{1} {2}High precision LEP data and convergence of couplings:
physics is not ...Euclidean geometry}{2} {3}Interconnections between the measured
quantities due to Unification}{7} {4}The origin of $M_{SUSY}$ and why it should
be abandoned: masses and spectra are needed}{13} {5}The new step forward:
Supergravity}{21} {6}The SU(5) Supergravity Model}{22} {7}SU(5)xU(1)
Supergravity}{32} {8}Detailed calculations for the Tevatron}{47} {9}Detailed
calculations for LEP}{48} {10}Detailed calculations for HERA}{53} {11}Detailed
calculations for Underground Labs and Underwater facilities}{55} {12}Detailed
calculations for indirect experimental detection}{65} {13}The problem of mass
and $m_t$}{73} {14}Conclusions}{77}
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