4,649 research outputs found
Inelastic Dark Matter and the SABRE Experiment
We present here the sensitivity of the SABRE (Sodium iodide with Active
Background REjection) experiment to benchmark proto-philic, spin dependent,
Inelastic Dark Matter models previously proposed due to their lowered tension
with existing experimental results. We perform fits to cross section, mass, and
mass splitting values to find the best fit to DAMA/LIBRA data for these models.
In this analysis, we consider the Standard Halo Model (SHM), as well as an
interesting extension upon it, the SHM+Stream distribution, to investigate the
influence of the Dark Matter velocity distribution upon experimental
sensitivity and whether or not its consideration may be able to help relieve
the present experimental tension. Based on our analysis, SABRE should be
sensitive to all the three benchmark models within 3-5 years of data taking.Comment: Adjusted for full DAMA run 1+2 efficiency. Updated to match published
versio
Impact of sublingual immunotherapy on seasonal asthma and skin reactivity in children allergic to Parietaria pollen treated with inhaled fluticasone propionate
Immunotherapy is a recognized treatment for allergic respiratory diseases
Bremsstrahlung simulation in K to pi l^pm nu_l (gamma) decays
In physics simulation chains, the PHOTOS Monte Carlo program is often used to
simulate QED effects in decays of intermediate particles and resonances. The
program is based on an exact multiphoton phase space. In general, the matrix
element is obtained from iterations of a universal kernel and approximations
are involved. To evaluate the program precision, it is necessary to formulate
and implement within the generator the exact matrix element, which depends on
the decay channel. Then, all terms necessary for non-leading logarithms are
taken into account.
In the present letter we focus on the decay K to pi l^pm nu_l and tests of
the PHOTOS Monte Carlo program. We conclude a 0.2% relative precision in the
implementation of the hard photon matrix element into the emission kernel,
including the case where approximations are used.Comment: 1+20 pages, 8 figure
PHOTOS Monte Carlo and its theoretical accuracy
Because of properties of QED, the bremsstrahlung corrections to decays of
particles or resonances can be calculated, with a good precision, separately
from other effects. Thanks to the widespread use of event records such
calculations can be embodied into a separate module of Monte Carlo simulation
chains, as used in High Energy Experiments of today. The PHOTOS Monte Carlo
program is used for this purpose since nearly 20 years now. In the following
talk let us review the main ideas and constraints which shaped the program
version of today and enabled it widespread use. Finally, we will underline
importance of aspects related to reliability of program results: event record
contents and implementation of channel specific matrix elements.Comment: Presented by Z. Was, April 08 2008, International Workshop on e+e-
collisions from Phi to Ps
Two Photon Radiation in W and Z Boson Production at the Tevatron Collider
We present a calculation of two photon radiation in W and Z boson production
in hadronic collisions, based on the complete matrix elements for the processes
q\bar q'\to\ell^\pm\nu\gamma\gamma and q\bar q\to\ell^+\ell^-\gamma\gamma,
including finite charged lepton masses. In order to achieve stable numerical
results over the full phase space, multiconfiguration Monte Carlo techniques
are used to map the peaks in the differential cross section. Numerical results
are presented for the Fermilab Tevatron.Comment: Revtex, 28 pages, 3 figure
Matching NLO parton shower matrix element with exact phase space: case of W -> l nu (gamma) and gamma^* -> pi^+pi^-(gamma)
The PHOTOS Monte Carlo is often used for simulation of QED effects in decay
of intermediate particles and resonances. Momenta are generated in such a way
that samples of events cover the whole bremsstrahlung phase space. With the
help of selection cuts, experimental acceptance can be then taken into account.
The program is based on an exact multiphoton phase space. Crude matrix element
is obtained by iteration of a universal multidimensional kernel. It ensures
exact distribution in the soft photon region. Algorithm is compatible with
exclusive exponentiation. To evaluate the program's precision, it is necessary
to control the kernel with the help of perturbative results. If available,
kernel is constructed from the exact first order matrix element. This ensures
that all terms necessary for non-leading logarithms are taken into account. In
the present paper we will focus on the W -> l nu and gamma^* -> pi^+ pi^-
decays. The Born level cross sections for both processes approach zero in some
points of the phase space. A process dependent compensating weight is
constructed to incorporate the exact matrix element, but is recommended for use
in tests only. In the hard photon region, where scalar QED is not expected to
be reliable, the compensating weight for gamma^* decay can be large. With
respect to the total rate, the effect remains at the permille level. It is
nonetheless of interest. The terms leading to the effect are analogous to some
terms appearing in QCD. The present paper can be understood either as a
contribution to discussion on how to match two collinear emission chains
resulting from charged sources in a way compatible with the exact and complete
phase space, exclusive exponentiation and the first order matrix element of QED
(scalar QED), or as the practical study of predictions for accelerator
experiments.Comment: 24 page
Recent developments in radiative B decays
We report on recent theoretical progress in radiative B decays. We focus on a
calculation of logarithmically enhanced QED corrections to the branching ratio
and forward-backward asymmetry in the inclusive rare decay anti-B --> X(s) l+
l-, and present the results of a detailed phenomenological analysis. We also
report on the calculation of NNLO QCD corrections to the inclusive decay anti-B
--> X(s) gamma. As far as exclusive modes are concerned we consider
transversity amplitudes and the impact of right-handed currents in the
exclusive anti-B --> K^* l+ l- decay. Finally, we state results for exclusive B
--> V gamma decays, notably the time-dependent CP-asymmetry in the exclusive B
--> K^* gamma decay and its potential to serve as a so-called ``null test'' of
the Standard Model, and the extraction of CKM and unitarity triangle parameters
from B --> (rho,omega) gamma and B --> K^* gamma decays.Comment: 5 pages, 2 figures. Accepted for publication in the proceedings of
International Europhysics Conference on High Energy Physics (EPS-HEP2007),
Manchester, England, 19-25 Jul 200
Radiative corrections in decay
The final state interaction of pions in the decay allows to obtain the value of the isospin and angular
momentum zero pion-pion scattering length . To extract this quantity
from experimental data the radiative corrections (RC) have to be taken into
account. Basing on the lowest order results and the factorization hypothesis,
we get the expressions for RC in the leading and next-to leading logarithmical
approximation. It is shown that the decay width dependence on the lepton mass
through the parameter
\sigma=\frac{\alpha}{2\pi}\br{\ln\frac{M^2}{m_e^2}-1} has a standard form of
the Drell-Yan process and is proportional to the Sommerfeld-Sakharov factor.
The numerical estimations are presented.Comment: 11 pages, 5 figures, 1 table, some minor misprints are correcte
Universal Interface of TAUOLA Technical and Physics Documentation
Because of their narrow width, tau decays can be well separated from their
production process. Only spin degrees of freedom connect these two parts of the
physics process of interest for high energy collision experiments. In the
following, we present a Monte Carlo algorithm which is based on that property.
The interface supplements events generated by other programs, with tau decays.
Effects of spin, genuine weak corrections or of new physics may be taken into
account at the time when a tau decay is generated and written into an event
record.Comment: 1+44 pages, 17 eps figure
Isospin Violation and the Magnetic Moment of the Muon
We calculate the leading isospin-violating and electromagnetic corrections
for the decay tau -> pi^0 pi nu_tau at low energies. The corrections are small
but relevant for the inclusion of tau decay data in the determination of
hadronic vacuum polarization especially for the anomalous magnetic moment of
the muon. We show that part of the systematic differences between the measured
form factors in tau -> pi^0 pi nu_tau and e^+ e^- -> pi^+ pi^- is due to
isospin violation .Comment: 12 pages, 2 figures, minor revisions in the text, references added,
version to appear in Physics Letters
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