Dark Matter after BESS-Polar II. (arXiv:1110.4376v1 [hep-ph])

The BESS-Polar collaboration has recently performed a precise measurement of
the local antiproton flux which is consistent with a pure secondary production
of antiprotons. We constrain a possible primary component originating from dark
matter pair-annihilations. We derive limits on the annihilation cross section
which are stronger than or comparable to those from the PAMELA satellite
experiment for dark matter masses up to 200 GeV. Especially, we exclude thermal
WIMPs with masses in the range 3-20 GeV if they annihilate dominantly into
quark pairs unless their cross section is velocity suppressed.

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Heavy Quark Dynamics in the QGP. (arXiv:1110.4138v1 [hep-ph])

We assess transport properties of heavy quarks in the Quark-Gluon Plasma
(QGP) that show a strong non-perturbative behavior. A T-matrix approach based
on a potential taken from lattice QCD hints at the presence of heavy-quark (HQ)
resonant scattering with an increasing strength as the temperature, $ T$ ,
reaches the critical temperature, $ T_c \simeq 170 \; \MeV$ for deconfinement
from above. The implementation of HQ resonance scattering along with a
hadronization via quark coalescence under the conditions of the plasma created
in heavy-ion collisions has been shown to correctly describe both the nuclear
modification factor, $ R_{AA}$ , and the elliptic flow, $ v_2$ , of single
electrons at RHIC and have correctly predicted the $ R_{AA}$ of D mesons at LHC
energy.

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Stability of nodal structures in graph eigenfunctions and its relation to the nodal domain count. (arXiv:1110.3802v1 [math-ph])

The nodal domains of eigenvectors of the discrete Schrodinger operator on
simple, finite and connected graphs are considered. Courant’s well known nodal
domain theorem applies in the present case, and sets an upper bound to the
number of nodal domains of eigenvectors: Arranging the spectrum as a non
decreasing sequence, and denoting by $ \nu_n$ the number of nodal domains of the
$ n$ ‘th eigenvector, Courant’s theorem guarantees that the nodal deficiency
$ n-\nu_n$ is non negative. (The above applies for generic eigenvectors. Special
care should be exercised for eigenvectors with vanishing components.) The main
result of the present work is that the nodal deficiency for generic
eigenvectors equals to a Morse index of an energy functional whose value at its
relevant critical points coincides with the eigenvalue. The association of the
nodal deficiency to the stability of an energy functional at its critical
points was recently discussed in the context of quantum graphs
[arXiv:1103.1423] and Dirichlet Laplacian in bounded domains in $ R^d$
[arXiv:1107.3489]. The present work adapts this result to the discrete case.
The definition of the energy functional in the discrete case requires a special
setting, substantially different from the one used in
[arXiv:1103.1423,arXiv:1107.3489] and it is presented here in detail.

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Studying Deeply Virtual Compton Scattering with Neural Networks. (arXiv:1110.3798v1 [physics.data-an])

Neural networks are utilized to fit Compton form factor H to HERMES data on
deeply virtual Compton scattering off unpolarized protons. We used this result
to predict the beam charge-spin assymetry for muon scattering off proton at the
kinematics of the COMPASS II experiment.

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The magnetic mass of transverse gluon, the B-meson weak decay vertex and the triality symmetry of octonion. (arXiv:1110.3857v1 [hep-ph])

With an assumption that in the Yang-Mills Lagrangian, a left-handed fermion
and a right-handed fermion both expressed as quaternion make an octonion which
possesses the triality symmetry, I calculate the magnetic mass of the
transverse self-dual gluon from three loop diagram, in which a heavy quark pair
is created and two self-dual gluons are interchanged.

The magnetic mass of the transverse gluon depends on the mass of the pair
created quarks, and in the case of charmed quark pair creation, the magnetic
mass $ m_{mag}$ becomes approximately equal to $ T_c$ at $ T=T_c\sim
1.14\Lambda_{\bar{MS}}\sim 260$ MeV. Corrections in the B-meson weak decay
vertex from the two self-dual gluon exchange is also evaluated.

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Gauge Field Production in Axion Inflation: Consequences for Monodromy, non-Gaussianity in the CMB, and Gravitational Waves at Interferometers. (arXiv:1110.3327v1 [astro-ph.CO])

Models of inflation based on axions, which owe their popularity to the
robustness against UV corrections, have also a very distinct class of
signatures. The relevant interactions of the axion are a non-perturbative
oscillating contribution to the potential and a shift-symmetric coupling to
gauge fields. We review how these couplings affect the cosmological
perturbations via a unified study based on the in-in formalism. We then note
that, when the inflaton coupling to gauge fields is high enough to lead to
interesting observational results, the backreaction of the produced gauge
quanta on the inflaton dynamics becomes relevant during the final stage of
inflation, and prolongs its duration by about 10 e-foldings. We extend existing
results on gravity wave production in these models to account for this late
inflationary phase. The strong backreaction phase results in an enhancement of
the gravity wave signal at the interferometer scales. As a consequence, the
signal is potentially observable at Advanced LIGO/VIRGO for the most natural
duration of inflation in such models. Finally, we explicitly compute the axion
couplings to gauge fields in string theory construction of axion monodromy
inflation and identify cases where they can trigger interesting
phenomenological effects.

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Hadron production in pA collisions at the LHC from the Color Glass Condensate. (arXiv:1110.2810v1 [hep-ph])

We investigate the contribution of inelastic and elastic processes to single
inclusive hadron production in proton-proton and proton (deuteron)-nucleus
collisions at RHIC and the LHC. Using the hybrid formulation which includes
both elastic and inelastic contributions, supplemented with the
running-coupling Balitsky-Kovchegov equation, we get a good description of RHIC
data. It is shown that inclusion of the inelastic terms makes the transverse
momentum dependence of the production cross section steeper in the mid-rapidity
region but does not affect the cross section in the very forward region. The
inelastic processes also lead to a sharper increase of the nuclear modification
factor R_{pA} with increasing p_T. We also make predictions for the nuclear
modification factor in proton-nucleus collisions at the LHC (\sqrt{s}=4.4 and
8.8 TeV) at forward rapidities using the Color-Glass-Condensate framework.

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Hawking radiation for a Proca field in D-dimensions. (arXiv:1110.2485v1 [gr-qc])

We study the wave equation of a massive vector boson in the background of a
D-dimensional Schwarzschild black hole. The mass term introduces a coupling
between two physical degrees of freedom of the field, and we solve the
resulting system of ODEs numerically, without decoupling. We show how to define
decoupled transmission factors from an S-matrix and compute them for various
modes, masses and space-time dimensions. The mass term lifts the degeneracy
between transverse modes, in D=4, and excites the longitudinal modes, in
particular the s-wave. Moreover, it increases the contribution of waves with
larger angular momentum, which can be dominant at intermediate energies. The
transmission factors are then used to obtain the Hawking fluxes in this
channel. Our results alert for the importance of modelling the longitudinal
modes correctly, instead of treating them as decoupled scalars as in current
black hole event generators; thus they can be used to improve such generators
for phenomenological studies of TeV gravity scenarios.

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Index Theorem and Overlap Formalism with Naive and Minimally Doubled Fermions. (arXiv:1110.2482v1 [hep-lat])

We present a theoretical foundation for the index theorem in naive and
minimally doubled lattice fermions by studying the spectral flow of a Hermitean
version of Dirac operators. We utilize the point splitting method to implement
flavored mass terms, which play an important role in constructing proper
Hermitean operators. We show the spectral flow correctly detects the index of
the would-be zero modes which is determined by gauge field topology and the
number of species doublers. Using the flavored mass terms, we present new types
of overlap fermions from the naive fermion kernels, with a number of flavors
that depends on the choice of the mass terms.

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Precision NNLO determination of alpha_s(M_Z) using an unbiased global parton set. (arXiv:1110.2483v1 [hep-ph])

We determine the strong coupling alpha_s at NNLO in perturbative QCD using
the global dataset input to the NNPDF2.1 NNLO parton fit: data from neutral and
charged current deep-inelastic scattering, Drell-Yan, vector boson production
and inclusive jets. We find alpha_s(M_Z)=0.1173+- 0.0007 (stat), where the
statistical uncertainty comes from the underlying data and uncertainties due to
the analysis procedure are negligible. We show that the distribution of alpha_s
values preferred by different experiments in the global fit is statistically
consistent, without need for rescaling uncertainties by a “tolerance” factor.
We show that if deep-inelastic data only are used, the best-fit value of
alpha_s is somewhat lower, but consistent within one sigma with the global
determination. We estimate the dominant theoretical uncertainty, from higher
orders corrections, to be Delta alpha_s (pert) ~ 0.0009.

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