47,824 research outputs found
Domain walls in supersymmetric QCD
We consider domain walls that appear in supersymmetric SU(N) with one massive
flavour. In particular, for N > 3 we explicitly construct the elementary domain
wall that interpolates between two contiguous vacua. We show that these
solutions are BPS saturated for any value of the mass of the matter fields. We
also comment on their large N limit and their relevance for supersymmetric
gluodynamics.Comment: 4 pages, 1 figure, uses latex with hep99 class files. Presented at
the International Europhysics Conference in High Energy Physics, Tampere
(Finland) 15-21 July 199
The 750 GeV Diphoton Excess as a First Light on Supersymmetry Breaking
One of the most exciting explanations advanced for the recent diphoton excess
found by ATLAS and CMS is in terms of sgoldstino decays: a signal of low-energy
supersymmetry-breaking scenarios. The sgoldstino, a scalar, couples directly to
gluons and photons, with strength related to gaugino masses, that can be of the
right magnitude to explain the excess. However, fitting the suggested resonance
width, Gamma ~ 45 GeV, is not so easy. In this paper we explore efficient
possibilities to enhance the sgoldstino width, via the decay into two Higgses,
two Higgsinos and through mixing between the sgoldstino and the Higgs boson. In
addition, we present an alternative and more efficient mechanism to generate a
mass splitting between the scalar and pseudoscalar components of the
sgoldstino, which has been suggested as an interesting alternative explanation
to the apparent width of the resonance.Comment: 14 pages, 3 figure
Energy partition and segregation for an intruder in a vibrated granular system under gravity
The difference of temperatures between an impurity and the surrounding gas in
an open vibrated granular system is studied. It is shown that, in spite of the
high inhomogeneity of the state, the temperature ratio remains constant in the
bulk of the system. The lack of energy equipartition is associated to the
change of sign of the pressure diffusion coefficient for the impurity at
certain values of the parameters of the system, leading to a segregation
criterium. The theoretical predictions are consistent with previous
experimental results, and also in agreement with molecular dynamics simulation
results reported in this paper.Comment: To appear in Phys. Rev. Let
Finite size scaling of the bayesian perceptron
We study numerically the properties of the bayesian perceptron through a
gradient descent on the optimal cost function. The theoretical distribution of
stabilities is deduced. It predicts that the optimal generalizer lies close to
the boundary of the space of (error-free) solutions. The numerical simulations
are in good agreement with the theoretical distribution. The extrapolation of
the generalization error to infinite input space size agrees with the
theoretical results. Finite size corrections are negative and exhibit two
different scaling regimes, depending on the training set size. The variance of
the generalization error vanishes for confirming the
property of self-averaging.Comment: RevTeX, 7 pages, 7 figures, submitted to Phys. Rev.
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