351 research outputs found
Study of Rapidity Gap Events in Hadronic Z Decays with L3 detector
Rapidity gaps have been studied in well separated completely symmetric 3 jet
events from hadronic Z decays to search for colour singlet exchange.
Asymmetries in particle flow and angular separation, defined with respect to
the inter-jet regions, are found to be sensitive to the exchange of a colour
singlet object instead of a colour octet gluon. %Comparing data from the L3
experiment with Monte Carlo predictions, %a limit is obtained on the fraction
%of colour singlet exchange in data. From a comparison of the distributions
observed in the L3 experiment and Monte Carlo predictions, a limit is obtained
on the fraction of colour singlet exchange in data.Comment: 4 pages, 7 figures (in eps) talk given at XXXI International
Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China. see
http://ismd31.ccnu.edu.cn
Search for a Light Higgs Boson at BaBar
We search for evidence of a light Higgs boson (A0) in the radiative decays of
the narrow Upsilon(3S) resonance: Upsilon(3S) -> gamma A0, where A0 ->
invisible or A0 -> mu+mu-. Such an object appears in extensions of the Standard
Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks.
We find no evidence for such processes in a sample of 122 million Upsilon(3S)
decays collected by the BaBar collaboration at the PEP II B-factory, and set
90% C.L. upper limits on the product of the corresponding branching fractions.
We also set a limit on the di-muon branching fraction of the recently
discovered eta_b meson.Comment: 8 pages, 4 figures. To appear in the proceedings of Les Rencontres de
Physique de la Valle'e d'Aoste held at La Thuile, Italy from 1-7 March 200
Sub-linear Upper Bounds on Fourier dimension of Boolean Functions in terms of Fourier sparsity
We prove that the Fourier dimension of any Boolean function with Fourier
sparsity is at most . Our proof method yields an
improved bound of assuming a conjecture of
Tsang~\etal~\cite{tsang}, that for every Boolean function of sparsity there
is an affine subspace of of co-dimension O(\poly\log s)
restricted to which the function is constant. This conjectured bound is tight
upto poly-logarithmic factors as the Fourier dimension and sparsity of the
address function are quadratically separated. We obtain these bounds by
observing that the Fourier dimension of a Boolean function is equivalent to its
non-adaptive parity decision tree complexity, and then bounding the latter
Towards Better Separation between Deterministic and Randomized Query Complexity
We show that there exists a Boolean function which observes the following
separations among deterministic query complexity , randomized zero
error query complexity and randomized one-sided error query
complexity : and
. This refutes the conjecture made by Saks
and Wigderson that for any Boolean function ,
. This also shows widest separation between
and for any Boolean function. The function was defined by
G{\"{o}}{\"{o}}s, Pitassi and Watson who studied it for showing a separation
between deterministic decision tree complexity and unambiguous
non-deterministic decision tree complexity. Independently of us, Ambainis et al
proved that different variants of the function certify optimal (quadratic)
separation between and , and polynomial separation between
and . Viewed as separation results, our results are subsumed
by those of Ambainis et al. However, while the functions considerd in the work
of Ambainis et al are different variants of , we work with the original
function itself.Comment: Reference adde
The zero-error randomized query complexity of the pointer function
The pointer function of G{\"{o}}{\"{o}}s, Pitassi and Watson
\cite{DBLP:journals/eccc/GoosP015a} and its variants have recently been used to
prove separation results among various measures of complexity such as
deterministic, randomized and quantum query complexities, exact and approximate
polynomial degrees, etc. In particular, the widest possible (quadratic)
separations between deterministic and zero-error randomized query complexity,
as well as between bounded-error and zero-error randomized query complexity,
have been obtained by considering {\em
variants}~\cite{DBLP:journals/corr/AmbainisBBL15} of this pointer function.
However, as was pointed out in \cite{DBLP:journals/corr/AmbainisBBL15}, the
precise zero-error complexity of the original pointer function was not known.
We show a lower bound of on the zero-error
randomized query complexity of the pointer function on bits;
since an upper bound is already known
\cite{DBLP:conf/fsttcs/MukhopadhyayS15}, our lower bound is optimal up to a
factor of \polylog\, n
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