7,228 research outputs found
The Method of Contrast and the Perception of Causality in Audition
The method of contrast is used within philosophy of perception in order to demonstrate that a specific property could be part of our perception. The method is based on two passages. I argue that the method succeeds in its task only if the intuition of the difference, which constitutes the core of the first passage, has two specific traits. The second passage of the method consists in the evaluation of the available explanations of this difference. Among the three outlined options, I will demonstrate that only in the third option – as we shall see, the case of the scenario that remains the same but is perceived in two different ways by the same perceiver – the intuition purports a difference that posses the necessary characteristics, namely being immediately evident and extremely complex and multifaceted, which determine its tensive nature. The application within auditory perception of this third option will generate two cases, a diachronic one and a synchronic one, which clearly show that we can auditorily perceive causality as a link between two sonorous episodes. The causal explanation is the only possible explanation among the many evaluated within the second passage of the method of contrast
Some considerations on pitch
Pitch is an audible quality of sound which can be explained not only in terms of strong correlation with sound waves’ properties, but also by a neat correlation to the properties of the sounding object. This seems to be in favour of the theory of sound labelled “distal view”, according to which sound is the vibration of the sounding object
New Formalism for Numerical Relativity
We present a new formulation of the Einstein equations that casts them in an
explicitly first order, flux-conservative, hyperbolic form. We show that this
now can be done for a wide class of time slicing conditions, including maximal
slicing, making it potentially very useful for numerical relativity. This
development permits the application to the Einstein equations of advanced
numerical methods developed to solve the fluid dynamic equations, {\em without}
overly restricting the time slicing, for the first time. The full set of
characteristic fields and speeds is explicitly given.Comment: uucompresed PS file. 4 pages including 1 figure. Revised version adds
a figure showing a comparison between the standard ADM approach and the new
formulation. Also available at http://jean-luc.ncsa.uiuc.edu/Papers/ Appeared
in Physical Review Letters 75, 600 (1995
Nonleptonic two-body B-decays including axial-vector mesons in the final state
We present a systematic study of exclusive charmless nonleptonic two-body B
decays including axial-vector mesons in the final state. We calculate branching
ratios of B\to PA, VA and AA decays, where A, V and P denote an axial-vector, a
vector and a pseudoscalar meson, respectively. We assume naive factorization
hypothesis and use the improved version of the nonrelativistic ISGW quark model
for form factors in B\to A transitions. We include contributions that arise
from the effective \Delta B=1 weak Hamiltonian H_{eff}. The respective
factorized amplitude of these decays are explicitly showed and their penguin
contributions are classified. We find that decays B^-to a_1^0\pi^-,\barB^0\to
a_1^{\pm}\pi^{\mp}, B^-\to a_1^-\bar K^0, \bar B^0\to a_1^+K^-, \bar B^0\to
f_1\bar K^0, B^-\to f_1K^-, B^-\to K_1^-(1400)\etap, B^-\to b_1^-\bar K^{0},
and \bar B^0\to b_1^+\pi^-(K^-) have branching ratios of the order of 10^{-5}.
We also study the dependence of branching ratios for B \to K_1P(V,A) decays
(K_1=K_1(1270),K_1(1400)) with respect to the mixing angle between K_A and K_B.Comment: 28 pages, 2 tables and one reference added, notation changed in
appendices, some numerical results and abstract correcte
CP Asymmetries in B to f_0 K_S Decays
We consider the branching ratio and the CP asymmetries in B to f_0(980)K_S
decay to the end of determining the deviation of the time-dependent CP
asymmetry from sin(2 beta) arising from Standard Model physics. We obtain Delta
S_{f_0 K_S} within the context of the QCD factorization framework for the B to
f_0(980)K_S decay amplitudes assuming the f_0(980) is a q\bar{q} state and
employing a random scan over the theoretical parameter space to assess the
possible range in Delta S_{f_0 K_S}. Imposing the value of the experimental
branching ratio within 1 sigma and 3 sigma, respectively, of its central value
as a constraint, we find the range of Delta S_{f_0 K_S} to be [0.018, 0.033]
for a scan in which the parameters are allowed to vary within 1 sigma of their
central values and the range [-0.019, 0.064] for a scan in which the parameters
vary within 3 sigma of their central values.Comment: 27 pages, 10 figures, references adde
A 3+1 covariant suite of Numerical Relativity Evolution Systems
A suite of three evolution systems is presented in the framework of the 3+1
formalism. The first one is of second order in space derivatives and has the
same causal structure of the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) system
for a suitable choice of parameters. The second one is the standard first order
version of the first one and has the same causal structure of the Bona-Masso
system for a given parameter choice. The third one is obtained from the second
one by reducing the space of variables in such a way that the only modes that
propagate with zero characteristic speed are the trivial ones. This last system
has the same structure of the ones recently presented by Kidder, Scheel and
Teukolski: the correspondence between both sets of parameters is explicitly
given. The fact that the suite started with a system in which all the dynamical
variables behave as tensors (contrary to what happens with BSSN system) allows
one to keep the same parametrization when passing from one system to the next
in the suite. The direct relationship between each parameter and a particular
characteristic speed, which is quite evident in the second and the third
systems, is a direct consequence of the manifest 3+1 covariance of the
approach
Strongly hyperbolic second order Einstein's evolution equations
BSSN-type evolution equations are discussed. The name refers to the
Baumgarte, Shapiro, Shibata, and Nakamura version of the Einstein evolution
equations, without introducing the conformal-traceless decomposition but
keeping the three connection functions and including a densitized lapse. It is
proved that a pseudo-differential first order reduction of these equations is
strongly hyperbolic. In the same way, densitized Arnowitt-Deser-Misner
evolution equations are found to be weakly hyperbolic. In both cases, the
positive densitized lapse function and the spacelike shift vector are arbitrary
given fields. This first order pseudodifferential reduction adds no extra
equations to the system and so no extra constraints.Comment: LaTeX, 16 pages, uses revtex4. Referee corections and new appendix
added. English grammar improved; typos correcte
Challenges for MSSM Higgs searches at Hadron Colliders
In this article we analyze the impact of B-physics and Higgs physics at LEP
on standard and non-standard Higgs bosons searches at the Tevatron and the LHC,
within the framework of minimal flavor violating supersymmetric models. The
B-physics constraints we consider come from the experimental measurements of
the rare B-decays b -> s gamma and B_u -> tau nu and the experimental limit on
the B_s -> mu+ mu- branching ratio. We show that these constraints are severe
for large values of the trilinear soft breaking parameter A_t, rendering the
non-standard Higgs searches at hadron colliders less promising. On the contrary
these bounds are relaxed for small values of A_t and large values of the
Higgsino mass parameter mu, enhancing the prospects for the direct detection of
non-standard Higgs bosons at both colliders. We also consider the available
ATLAS and CMS projected sensitivities in the standard model Higgs search
channels, and we discuss the LHC's ability in probing the whole MSSM parameter
space. In addition we also consider the expected Tevatron collider
sensitivities in the standard model Higgs h -> b bbar channel to show that it
may be able to find 3 sigma evidence in the B-physics allowed regions for small
or moderate values of the stop mixing parameter.Comment: 22 pages, 5 figures. Added references and acknowledgements. Submitted
to PR
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