62 research outputs found
Dark Matter in the Standard Model Extension with Singlet Quark
We analyze the possibility of hadron Dark Matter carriers consisting of
singlet quark and the light standard one. It is shown that stable singlet
quarks generate effects of new physics which do not contradict to restrictions
from precision electroweak data. The neutral and charged pseudoscalar low-lying
states are interpreted as the Dark Matter particle and its mass-degenerated
partner. We evaluated their masses and lifetime of the charged component, and
describe asymptotics of the potential of low-energy interactions of these
particles with nucleons and with each other. Some peculiarities of Sommerfeld
enhancement effect in the annihilation process are also discussed.Comment: 13 pages, 2 tabl
Composite scalar Dark Matter from vector-like confinement
A toy-model with dynamics confined at high scales
GeV enables to construct Dirac UV completion from the
original chiral multiplets predicting a vector-like nature of their weak
interactions consistent with electroweak precision tests. In this work, we
investigate a potential of the lightest scalar baryon-like (T-baryon) state
with mass TeV predicted by the simplest two-flavor
vector-like confinement model as a Dark Matter (DM) candidate. We show that two
different scenarios with the T-baryon relic abundance formation before and
after the electroweak (EW) phase transition epoch lead to symmetric (or mixed)
and asymmetric DM, respectively. Such a DM candidate evades existing direct DM
detection constraints since its vector coupling to boson absents at tree
level, while one-loop gauge boson mediated contribution is shown to be
vanishingly small close to the threshold. The dominating spin-independent (SI)
T-baryon--nucleon scattering goes via tree-level Higgs boson exchange in the
-channel. The corresponding bound on the effective T-baryon--Higgs coupling
has been extracted from the recent LUX data and turns out to be consistent with
naive expectations from the light technipion case . The latter provides the most stringent phenomenological
constraint on strongly-coupled dynamics so far. Future
prospects for direct and indirect scalar T-baryon DM searches in astrophysics
as well as in collider measurements have been discussed.Comment: 17 pages, 14 figures; an extra figure added, discussion of mass
splitting improved, minor corrections, conclusions unchange
Vector-like technineutron Dark Matter: is a QCD-type Technicolor ruled out by XENON100?
We continue to explore a question about the existence of a new strongly
coupled dynamics above the electroweak scale. The latter has been recently
realized in the simplest consistent scenario, the vector-like (or
chiral-symmetric) Technicolor model based upon the gauged linear sigma-model.
One of the predictions of a new strong dynamics in this model, the existence of
stable vector-like technibaryon states at a TeV scale, such that the lightest
neutral one could serve as a Dark Matter candidate. Here, we consider the
QCD-type Technicolor with SU(3)_TC confined group and one SU(2)_W doublet of
vector-like techniquarks and test this model against existing Dark Matter
astrophysics data. We show that the spin-independent Dirac
technineutron-nucleon cross section is by far too large and ruled out by
XENON100 data. We conclude that vector-like techniquark sectors with an odd
group of confinement SU(2n+1)_TC, n=1,2,... and with ordinary vector-like weak
SU(2)_W interactions are excluded if the technibaryon number is conserved. We
discuss a possible generic TC scenario with a technibaryon sector interacting
via an extra vector SU(2)_V other than the standard weak SU(2)_W and consider
immediate implications for the cosmological evolution and freeze out of heavy
relic technineutrons.Comment: 30 pages, 4 figures; extra clarification and motivation for the VLTC
scenario has been made; minor correction
Efficient motif finding algorithms for large-alphabet inputs
<p>Abstract</p> <p>Background</p> <p>We consider the problem of identifying motifs, recurring or conserved patterns, in the biological sequence data sets. To solve this task, we present a new deterministic algorithm for finding patterns that are embedded as exact or inexact instances in all or most of the input strings.</p> <p>Results</p> <p>The proposed algorithm (1) improves search efficiency compared to existing algorithms, and (2) scales well with the size of alphabet. On a synthetic planted DNA motif finding problem our algorithm is over 10× more efficient than MITRA, PMSPrune, and RISOTTO for long motifs. Improvements are orders of magnitude higher in the same setting with large alphabets. On benchmark TF-binding site problems (FNP, CRP, LexA) we observed reduction in running time of over 12×, with high detection accuracy. The algorithm was also successful in rapidly identifying protein motifs in Lipocalin, Zinc metallopeptidase, and supersecondary structure motifs for Cadherin and Immunoglobin families.</p> <p>Conclusions</p> <p>Our algorithm reduces computational complexity of the current motif finding algorithms and demonstrate strong running time improvements over existing exact algorithms, especially in important and difficult cases of large-alphabet sequences.</p
Complex-Mass Definition and the Structure of Unstable Particle’s Propagator
The propagators of unstable particles are considered in framework of the convolution representation. Spectral function is found for a special case when the propagator of scalar unstable particle has Breit-Wigner form. The expressions for the dressed propagators of unstable vector and spinor fields are derived in an analytical way for this case. We obtain the propagators in modified Breit-Wigner forms which correspond to the complex-mass definition
Finite-width effects in the near-threshold ZZZ and ZWW production at ILC
We calculate the cross-section of the near-threshold off-shell and
production at the International Linear Collider taking into account
their instability and the principal part of NLO corrections. The calculations
are performed in the framework of the model of unstable particles with smeared
mass-shell. We show that the contribution of the finite and widths
(their instability) is large in the Higgs resonance range and should be taken
into account in the Higgs boson searches at future colliders.Comment: 5 pages, 6 figure
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