8,368 research outputs found
Energy Level Diagrams for Black Hole Orbits
A spinning black hole with a much smaller black hole companion forms a
fundamental gravitational system, like a colossal classical analog to an atom.
In an appealing if imperfect analogy to atomic physics, this gravitational atom
can be understood through a discrete spectrum of periodic orbits. Exploiting a
correspondence between the set of periodic orbits and the set of rational
numbers, we are able to construct periodic tables of orbits and energy level
diagrams of the accessible states around black holes. We also present a closed
form expression for the rational q, thereby quantifying zoom-whirl behavior in
terms of spin, energy, and angular momentum. The black hole atom is not just a
theoretical construct, but corresponds to extant astrophysical systems
detectable by future gravitational wave observatories.Comment: 8 page
On signals of new physics in global event properties in pp collisions in the TeV energy domain
In the framework of the weighted superposition mechanism of different classes
of minimum bias events (or substructures), described by the negative binomial
multiplicity distribution, in possible scenarios for pp collisions in the TeV
energy domain, we explore global properties of an eventual new class of events,
characterised by high hadron and clan densities, to be added to the soft
(without minijets) and semihard (with minijets) ones. It turns out that the
main signal of the mentioned new physical expectations at 14 TeV c.m. energy
would be an ``elbow structure'' in the tail of the total charged particle
multiplicity distribution in complete disagreement with the second shoulder
structure predicted by Pythia Monte Carlo calculations: a challenging problem
for new experimental work.Comment: 14 pages, 6 ps figures include
Effective Hamiltonian Approach to Hyperon Beta Decay with Final-State Baryon Polarization
Using an effective Hamiltonian approach, we obtain expressions for hyperon
beta decay final-state baryon polarization. Terms through second order in the
energy release are retained. The resulting approximate expressions are much
simpler and more compact than the exact expressions, and they agree closely
with them.Comment: 1 Figure Will appear in Phys Rev D 60 Article 117505 (Dec 1, 1999
Prompt photon and associated heavy quark production at hadron colliders with kt-factorization
In the framework of the kt-factorization approach, the production of prompt
photons in association with a heavy (charm or beauty) quarks at high energies
is studied. The consideration is based on the O(\alpha \alpha_s^2) off-shell
amplitudes of gluon-gluon fusion and quark-(anti)quark interaction
subprocesses. The unintegrated parton densities in a proton are determined
using the Kimber-Martin-Ryskin prescription. The analysis covers the total and
differential cross sections and extends to specific angular correlations
between the produced prompt photons and muons originating from the semileptonic
decays of associated heavy quarks. Theoretical uncertainties of our evaluations
are studied and comparison with the results of standard NLO pQCD calculations
is performed. Our numerical predictions are compared with the recent
experimental data taken by the D0 and CDF collaborations at the Tevatron.
Finally, we extend our results to LHC energies.Comment: 14 pages, 10 figure
The exclusive B_s -> phi mu+ mu- process in a constituent quark model
We consider the exclusive B_s -> phi mu+ mu- process in the standard model
using a constituent quark loop model approach together with a simple
parameterization of the quark dynamics. The model allows to compute the decay
form factors and therefore can give predictions for the decay rates, the
invariant mass spectra and the asymmetries. This process is suppressed in the
standard model but can be enhanced if new physics beyond the standard model is
present, such as flavor-violating supersymmetric models. It constitutes
therefore an interesting precision test of the standard model at forthcoming
experiments.Comment: 17 pages, 6 figures, 5 tables, LaTeX; minor changes to the
introduction, table III and figure 3. Few references adde
Squark Mixing in Electron-Positron Reactions
Squark mixing plays a large role in the phenomenology of the minimal
supersymmetric standard model, determining the mass of the lightest Higgs boson
and the electroweak interactions of the squarks themselves. We examine how
mixing may be investigated in high energy reactions, both at LEP-II
and the proposed linear collider. In particular, off-diagonal production of one
lighter and one heavier squark allows one to measure the squark mixing angle,
and would allow one to test the mass relations for the light Higgs boson. In
some cases off-diagonal production may provide the best prospects to discover
supersymmetry. In the context of the light bottom squark scenario, we show that
existing data from LEP-II should show definitive evidence for the heavier
bottom squark provided that its mass GeV.Comment: 22 pages, latex, 6 figure
The Ratio of W + N jets To Z/gamma + N jets As a Precision Test of the Standard Model
We suggest replacing measurements of the individual cross-sections for the
production of W + N jets and Z/gamma + N jets in searches for new high-energy
phenomena at hadron colliders by the precision measurement of the ratios (W+0
jet)/(Z+0 jet), (W+1 jet)/(Z+1 jet), (W+2 jets)/(Z+2 jets),... (W+N jets)/(Z+N
jets), with N as large as 6 (the number of jets in ttbarH). These ratios can
also be formed for the case where one or more of the jets is tagged as a b or c
quark. Existing measurements of the individual cross sections for Wenu + N jets
at the Tevatron have systematic uncertainties that grow rapidly with N, being
dominated by uncertainties in the identification of jets and the jet energy
scale. These systematics, and also those associated with the luminosity, parton
distribution functions (PDF's), detector acceptance and efficiencies, and
systematics of jet finding and b-tagging, are expected to substantially cancel
in calculating the ratio of W to Z production in each N-jet channel, allowing a
greater sensitivity to new contributions in these channels in Run II at the
Tevatron and at the LHC.Comment: 10 pages, 8 figures, added reference
Electroweak and finite width corrections to top quark decays into transverse and longitudinal -bosons
We calculate the electroweak and finite width corrections to the decay of an
unpolarized top quark into a bottom quark and a -gauge boson where the
helicities of the are specified as longitudinal, transverse-plus and
transverse-minus. Together with the corrections these
corrections may become relevant for the determination of the mass of the top
quark through angular decay measurements.Comment: 4 pages, 7 postscript figures adde
Three Numerical Puzzles and the Top Quark's Chiral Weak-Moment
Versus the standard model's t --> W b decay helicity amplitudes, three
numerical puzzles occur at the 0.1 % level when one considers the amplitudes in
the case of an additional (f_M + f_E) coupling of relative strength 53 GeV. The
puzzles are theoretical ones which involve the t --> W b decay helicity
amplitudes in the two cases, the relative strength of this additional coupling,
and the observed masses of these three particles. A deeper analytic realization
is obtained for two of them. Equivalent realizations are given for the
remaining one. An empirical consequence of these analytic realizations is that
it is important to search for effects of a large chiral weak-moment of the
top-quark, the effective mass-scale is about 53 GeV. A full theoretical
resolution would include relating the origin of such a chiral weak-moment and
the mass generation of the top-quark, the W-boson, and probably the b-quark.Comment: 18 pages, 1 postscript table (revised to better explain notation,
model #1, add a little material...
Inclusive Higgs boson and dijet production via Double Pomeron exchange
We evaluate Higgs boson and dijet cross-sections at the Tevatron collider via
Double Pomeron exchange when accompanying particles in the central region are
taken into account. Such {\it inclusive} processes, normalized to the observed
dijet rate observed at run I, noticeably increase the predictions for tagged
(anti)protons in the run II with respect to {\it exclusive} ones, with the
potentiality of Higgs boson detection.Comment: 6pages, 4 figure
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