2,630 research outputs found
Inverse Slope Systematics in High-Energy p+p and Au+Au Reactions
We employ the Monte-Carlo PYTHIA to calculate the transverse mass spectra of
various hadrons and their inverse slopes T* at m_T-m=1.5-2 GeV in p+p reactions
at sqrt(s)=200 GeV. Due to (multiple) minijet production T* increases as a
function of the hadron mass. Moreover, the T*(m) systematics has a
``discontinuity'' at the charm threshold, i.e. the inverse slope of D-mesons is
much higher than that of non-charmed hadrons and even of the heavier Lambda_C
baryon. The experimental observation of this characteristic behaviour in Au+Au
collisions would indicate the absence of c-quark rescattering. In contrast, the
assumption of thermalized partons and hydrodynamical evolution would lead to a
smoothly increasing T*(m), without discontinuity at the charm threshold. The
degree of collective transverse flow, indicated by the slope of the T*(m)
systematics, depends strongly on whether kinetic equilibrium is maintained for
some time after hadronization or not.Comment: 14 pages, 2 figures, REVTEX; mistake in plot of c-quark
mt-distribution corrected, some references adde
Resonance-free Region in scattering by a strictly convex obstacle
We prove the existence of a resonance free region in scattering by a strictly
convex obstacle with the Robin boundary condition. More precisely, we show that
the scattering resonances lie below a cubic curve which is the same as in the
case of the Neumann boundary condition. This generalizes earlier results on
cubic poles free regions obtained for the Dirichlet boundary condition.Comment: 29 pages, 2 figure
Upper bound on the density of Ruelle resonances for Anosov flows
Using a semiclassical approach we show that the spectrum of a smooth Anosov
vector field V on a compact manifold is discrete (in suitable anisotropic
Sobolev spaces) and then we provide an upper bound for the density of
eigenvalues of the operator (-i)V, called Ruelle resonances, close to the real
axis and for large real parts.Comment: 57 page
QCD aspects of leptoquark production at HERA
If a leptoquark is produced at HERA as a narrow resonance, various effects
tend to broaden the measurable mass distribution considerably. These effects
are discussed here, with special emphasis on initial- and final-state QCD
radiation. A proper understanding is important to assess the significance of
data and to devise strategies for better mass reconstruction.Comment: 1+8 pages, LaTeX2e, 4 eps figures included as separate file
Resolvent estimates for normally hyperbolic trapped sets
We give pole free strips and estimates for resolvents of semiclassical
operators which, on the level of the classical flow, have normally hyperbolic
smooth trapped sets of codimension two in phase space. Such trapped sets are
structurally stable and our motivation comes partly from considering the wave
equation for Kerr black holes and their perturbations, whose trapped sets have
precisely this structure. We give applications including local smoothing
effects with epsilon derivative loss for the Schr\"odinger propagator as well
as local energy decay results for the wave equation.Comment: Further changes to erratum correcting small problems with Section 3.5
and Lemma 4.1; this now also corrects hypotheses, explicitly requiring
trapped set to be symplectic. Erratum follows references in this versio
Pseudorapidity Distribution of Charged Particles in PbarP Collisions at root(s)= 630GeV
Using a silicon vertex detector, we measure the charged particle
pseudorapidity distribution over the range 1.5 to 5.5 using data collected from
PbarP collisions at root s = 630 GeV. With a data sample of 3 million events,
we deduce a result with an overall normalization uncertainty of 5%, and typical
bin to bin errors of a few percent. We compare our result to the measurement of
UA5, and the distribution generated by the Lund Monte Carlo with default
settings. This is only the second measurement at this level of precision, and
only the second measurement for pseudorapidity greater than 3.Comment: 9 pages, 5 figures, LaTeX format. For ps file see
http://hep1.physics.wayne.edu/harr/harr.html Submitted to Physics Letters
Black Holes at the LHC
If the scale of quantum gravity is near a TeV, the LHC will be producing one
black hole (BH) about every second. The BH decays into prompt, hard photons and
charged leptons is a clean signature with low background. The absence of
significant missing energy allows the reconstruction of the mass of the
decaying BH. The correlation between the BH mass and its temperature, deduced
from the energy spectrum of the decay products, can test experimentally the
higher dimensional Hawking evaporation law. It can also determine the number of
large new dimensions and the scale of quantum gravity.Comment: 5 pages, 3 figures, submitted to PRL. Results presented at the Les
Houches Workshop "Physics at the TeV Colliders" (May 30, 2001) and the
"Avatars of M-Theory" conference, ITP at Santa Barbara (June 7, 2001),
http://online.itp.ucsb.edu/online/mtheory_c01/dimopoulo
Color separate singlets in annihilation
We use the method of color effective Hamiltonian to study the properties of
states in which a gluonic subsystem forms a color singlet, and we will study
the possibility that such a subsystem hadronizes as a separate unit. A parton
system can normally be subdivided into singlet subsystems in many different
ways, and one problem arises from the fact that the corresponding states are
not orthogonal. We show that if only contributions of order are
included, the problem is greatly simplified. Only a very limited number of
states are possible, and we present an orthogonalization procedure for these
states. The result is simple and intuitive and could give an estimate of the
possibility to produce color separated gluonic subsystems, if no dynamical
effects are important. We also study with a simple MC the possibility that
configurations which correspond to "short strings" are dynamically favored. The
advantage of our approach over more elaborate models is its simplicity, which
makes it easier to estimate color reconnection effects in reactions which are
more complicated than the relatively simple annihilation.Comment: Revtex, 24 pages, 7 figures; Compared to the previous version, 1 new
figure is added and Monte-Carlo results are re-analyzed, as suggested by the
referee; To appear in Phys. Rev.
Decisive test for the Pomeron at Tevatron
We propose a new measurement to be performed at the Tevatron which can be
decisive to distinguish between Pomeron-based and soft color interaction models
of hard diffractive scattering.Comment: 5 pages, 3 figures, 1 tabel revtex forma
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