4,362 research outputs found

### Model-Independent Properties of the B-Meson Distribution Amplitude

The operator product expansion is used to obtain model-independent
predictions for the first two moments of the renormalized B-meson light-cone
distribution amplitude phi_+(omega,mu), defined with a cutoff omega<Lambda_UV.
The leading hadronic power corrections are given in terms of the parameter
Lambda(bar)=m_B-m_b. From the cutoff dependence of the zeroth moment an
analytical expression for the asymptotic behavior of the distribution amplitude
is derived, which exhibits a negative radiation tail for omega>>mu. By solving
the evolution equation for the distribution amplitude, an integral
representation for phi_+(omega,mu) is obtained in terms an initial function
phi_+(omega,mu_0) defined at a lower renormalization scale. A realistic model
of the B-meson light-cone distribution amplitude is proposed, which satisfies
the moment relations and has the correct asymptotic behavior. This model
provides an estimate for the first inverse moment and the associated parameter
lambda_B.Comment: 8 pages, 5 figures; problem in Figure 4 fixed, references updated;
version to appear in Phys. Rev.

### A Short Guide to Flavour Physics and CP Violation

We present the invited lectures given at the second Asia-Europe-Pacific
School of High-Energy Physics (AEPSHEP), which took place in Puri, India in
November 2014. The series of lectures aimed at graduate students in particle
experiment/theory, covering the very basics of flavor physics and CP violation,
some useful theoretical methods such as OPE and effective field theories, and
some selected topics of flavour physics in the era of LHC.Comment: 51 pages, 19 figures, paper submitted for publication in a CERN
Yellow Report (YR

### Radion Phenomenology in Realistic Warped Space Models

We investigate the phenomenology of the Randall-Sundrum radion in realistic
models of electroweak symmetry breaking with bulk gauge and fermion fields,
since the radion may turn out to be the lightest particle in such models. We
calculate the coupling of the radion in such scenarios to bulk fermion and
gauge modes. Special attention needs to be devoted to the coupling to massless
gauge fields (photon, gluon), since it is well known that loop effects may be
important for these fields. We also present a detailed explanation of these
couplings from the CFT interpretation. We then use these couplings to determine
the radion branching fractions and discuss some of the discovery potential of
the LHC for the radion. We find that the gamma-gamma signal is enhanced over
most of the range of the radion mass over the gamma-gamma signal of a SM Higgs,
as long as the RS scale is sufficiently low. However, the signal significance
depends strongly on free parameters that characterize the magnitude of bare
brane-localized kinetic terms for the massless gauge fields. In the absence of
such terms, the signal can be be enhanced over the traditional RS1 models
(where all standard model fields are localized on the IR brane), but the signal
can also be reduced compared to RS1 if the brane localized terms are sizeable.
We also show that for larger radion masses, where the gamma-gamma signal is no
longer significant, one can use the usual 4 lepton signal to discover the
radion.Comment: 28 pages, 7 figure

### Collapse transition of a square-lattice polymer with next nearest-neighbor interaction

We study the collapse transition of a polymer on a square lattice with both
nearest-neighbor and next nearest-neighbor interactions, by calculating the
exact partition function zeros up to chain length 36. The transition behavior
is much more pronounced than that of the model with nearest-neighbor
interactions only. The crossover exponent and the transition temperature are
estimated from the scaling behavior of the first zeros with increasing chain
length. The results suggest that the model is of the same universality class as
the usual theta point described by the model with only nearest-neighbor
interaction.Comment: 14 pages, 5 figure

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