2,561 research outputs found
Discrepancy and Signed Domination in Graphs and Hypergraphs
For a graph G, a signed domination function of G is a two-colouring of the
vertices of G with colours +1 and -1 such that the closed neighbourhood of
every vertex contains more +1's than -1's. This concept is closely related to
combinatorial discrepancy theory as shown by Fueredi and Mubayi [J. Combin.
Theory, Ser. B 76 (1999) 223-239]. The signed domination number of G is the
minimum of the sum of colours for all vertices, taken over all signed
domination functions of G. In this paper, we present new upper and lower bounds
for the signed domination number. These new bounds improve a number of known
results.Comment: 12 page
Description of soft diffraction in the framework of reggeon calculus. Predictions for LHC
A model, based on Gribov's Reggeon calculus, is proposed and applied to
processes of soft diffraction at high energies. It is shown that by accounting
for absorptive corrections for all legs of triple-Regge and loop diagrams a
good description of experimental data on inelastic soft diffraction can be
obtained. In this paper we give a brief description of the model and of its
predictions for LHC energies.Comment: Talk given at EDS'09 conferenc
Spectra of particles produced in high-mass diffraction dissociation in the Model of Quark-Gluon Strings
We calculate spectra of secondary particles produced in process of single
diffraction dissociation in the Model of Quark-Gluon Strings. For description
of diffractive dissociation process we use the reggeon model where all legs of
triple-reggeon diagrams are eikonalized. Numerical calculation shows that the
model gives a good description of data on charged particles pseudorapidity
distribution in single diffractive dissociation
Geometric expansion of the log-partition function of the anisotropic Heisenberg model
We study the asymptotic expansion of the log-partition function of the
anisotropic Heisenberg model in a bounded domain as this domain is dilated to
infinity. Using the Ginibre's representation of the anisotropic Heisenberg
model as a gas of interacting trajectories of a compound Poisson process we
find all the non-decreasing terms of this expansion. They are given explicitly
in terms of functional integrals. As the main technical tool we use the cluster
expansion method.Comment: 38 page
Measurement of , K, p transverse momentum spectra with ALICE in proton-proton collisions at 0.9 and 7 TeV
Results of the measurement of the , K, p transverse momentum
() spectra at mid-rapidity in proton-proton collisions at
TeV are presented. Particle identification was performed using
the energy loss signal in the Inner Tracking System (ITS) and the Time
Projection Chamber (TPC), while information from the Time-of-Flight (TOF)
detector was used to identify particles at higher transverse momentum. From the
spectra at TeV the mean transverse momentum ()
and particle ratios were extracted and compared to results obtained for
collisions at TeV and lower energies.Comment: Quark Matter 2011 proceeding
Role of gluons in soft and semi-hard multiple hadron production in pp collisions at LHC
Hadron inclusive spectra in pp collisions are analyzed within the modified
quark-gluon string model including both the longitudinal and transverse motion
of quarks in the proton in the wide region of initial energies. The
self-consistent analysis shows that the experimental data on the inclusive
spectra of light hadrons like pions and kaons at ISR energies can be
satisfactorily described at transverse momenta not larger than 1-2 GeV/c. We
discuss some difficulties to apply this model at energies above the ISR and
suggest to include the distribution of gluons in the proton unintegrated over
the internal transverse momentum. It leads to an increase in the inclusive
spectra of hadrons and allows us to extend the satisfactory description of the
data in the central rapidity region at energies higher than ISR.Comment: 19 pages, 20 figure
Towards the NNLL precision in
The present NLL prediction for the decay rate of the rare inclusive process
has a large uncertainty due to the charm mass
renormalization scheme ambiguity. We estimate that this uncertainty will be
reduced by a factor of 2 at the NNLL level. This is a strong motivation for the
on-going NNLL calculation, which will thus significantly increase the
sensitivity of the observable to possible new degrees
of freedom beyond the SM. We also give a brief status report of the NNLL
calculation.Comment: 5 pages, 2 figures, contribution to the proceedings of EPS-HEP 200
Abstract cluster expansion with applications to statistical mechanical systems
We formulate a general setting for the cluster expansion method and we discuss sufficient criteria for its convergence. We apply the results to systems of classical and quantum particles with stable interactions
Reduction of Charm Quark Mass Scheme Dependence in at the NNLL Level
The uncertainty of the theoretical prediction of the
branching ratio at NLL level is dominated by the charm mass renormalization
scheme ambiguity. In this paper we calculate those NNLL terms which are related
to the renormalization of , in order to get an estimate of the
corresponding uncertainty at the NNLL level. We find that these terms
significantly reduce (by typically a factor of two) the error on induced by the definition of . Taking into account the
experimental accuracy of around 10% and the future prospects of the
factories, we conclude that a NNLL calculation would increase the sensitivity
of the observable to possible new degrees of freedom
beyond the SM significantly.Comment: 13 pages including 3 figure
- …