4,446,291 research outputs found
Leading neutron spectra
It is shown that the observation of the spectra of leading neutrons from
proton beams can be a good probe of absorptive and migration effects. We
quantify how these effects modify the Reggeized pion-exchange description of
the measurements of leading neutrons at HERA. We are able to obtain a
satisfactory description of all the features of these data. We also briefly
discuss the corresponding data for leading baryons produced in hadron-hadron
collisions.Comment: 17 pages, 8 figures; sentence and reference added, reference
corrected, to be published in EPJ
Determining the Stau Trilinear Coupling A_tau in Supersymmetric Higgs Decays
The measurement of the trilinear couplings A in the part of the Lagrangian
which breaks supersymmetry softly will be a difficult experimental task. In
this report the heavy Higgs decays H,A -> stau_1 stau_2 to stau pairs are
investigated for measuring the stau trilinear coupling A_tau. Based on detailed
simulations of signal and backgrounds for a specific reference point in future
high luminosity e+e- linear collider experiments, it is concluded that the
parameter $_tau can be determined with a precision at the 10% level in the
region of moderate to large tan(beta).Comment: 13 page
Signals of new physics in global event properties in pp collisions in the TeV energy domain: rapidity intervals
The study of possible new physics signals in global event properties in pp
collisions in the TeV energy domain is extended from full phase-space to
rapidity intervals experimentally accessible at LHC. The elbow structure in the
total multiplicity distribution predicted in full phase-space is clearly
present also in restricted rapidity intervals, leading to very strong charged
particle correlations. It is also found that energy densities comparable to
those reached in heavy ion collisions at RHIC could be attained in pp
collisions at LHC.Comment: 10 pages, 4 figure
Leading-particle suppression in high energy nucleus-nucleus collisions
Parton energy loss effects in heavy-ion collisions are studied with the Monte
Carlo program PQM (Parton Quenching Model) constructed using the BDMPS
quenching weights and a realistic collision geometry. The merit of the approach
is that it contains only one free parameter that is tuned to the high-pt
nuclear modification factor measured in central Au-Au collisions at sqrt{s_NN}
= 200 GeV. Once tuned, the model is coherently applied to all the high-pt
observables at 200 GeV: the centrality evolution of the nuclear modification
factor, the suppression of the away-side jet-like correlations, and the
azimuthal anisotropies for these observables. Predictions for the
leading-particle suppression at nucleon-nucleon centre-of-mass energies of 62.4
and 5500 GeV are calculated. The limits of the eikonal approximation in the
BDMPS approach, when applied to finite-energy partons, are discussed.Comment: 28 pages, 14 figures, final version, accepted by Eur. Phys. J.
Improved Phase Space Treatment of Massive Multi-Particle Final States
In this paper the revised Kajantie-Byckling approach and improved phase space
sampling techniques for the massive multi-particle final states are presented.
The application of the developed procedures to the processes representative for
LHC physics indicates the possibility of a substantial simplification of
multi-particle phase space sampling while retaining a respectable weight
variance reduction and unweighing efficiencies in the event generation process.Comment: Minor stilistic changes, submitted to EPJ
Measuring the Higgs boson parity at a Linear Collider using the tau impact parameter and tau --> rho nu decay
We demonstrate that a measurement of the impact parameter in one-prong tau
decay can be useful for the determination of the Higgs boson parity in the H/A
--> tau tau; tau --> rho nu decay chain. We have estimated that for a detection
set-up such as TESLA, use of the information from the tau impact parameter can
improve the significance of the measurement of the parity of the Standard Model
120 GeV Higgs boson to 4.5 sigma, and in general by factor of about 1.5 with
respect to the method where this information is not used.
We also show that the variation in the assumption on the precision of the
measurement of the impact parameter and/or pi's momenta does not affect the
sensitivity of the method. This is because the method remains limited by the
type of twofold ambiguity in reconstructing the tau momentum.Comment: 12 pages, 12 figures, LaTe
Incidences of asymmetries for the palmar grasp reflex in neonates and hand preference in adults
It was hypothesized that adult handedness might be predicted from the neonatal grasp reflex. Grasp reflex was measured from right and left hand (10 trials for each hand) in neonates. According to significance for the difference between the mean grasp reflex strength from the right and left hands, the subjects were designated as right-, left-, and mixed-handers. Adult hand preference was assessed by Edinburgh Handedness Inventory. The percentage of left-handedness (8.3%) in neonates coincided with adult left-handedness (6.3-9.2%). The percentage of consistent right-hand preference in adults coincided with percentage of right-handedness in neonates (25.7%). The high percentage of neonatal mixed-handedness was similar to that to be expected from the right shift model of hand preference. It was concluded that left-handedness and consistent right- handedness may be determined prenatally, under genetic and/or hormonal control, and that a large majority of neonatal handedness, mixed-handers, might change their hand preference in favor of right-handedness under socio-cultural and developmental influences of speech centres
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