15,027 research outputs found
Higgs Phenomenology of Minimal Universal Extra Dimensions
The minimal model of Universal Extra Dimensions (MUED) is briefly reviewed.
We explain how the cross-sections for Higgs production via gluon fusion and
decay into two photons are modified, relative the the Standard Model (SM)
values, by KK particles running in loops, leading to an enhancement of the gg
to h to two photons and gg to h to W+W- cross-sections. ATLAS and CMS searches
for the SM Higgs in these channels are reinterpreted in the context of MUED and
used to place new limits on the MUED parameter space. Only a small region of
between 1 and 3 GeV around mh = 125 GeV for 500 GeV < 1/R < 1600 GeV remains
open at the 95 % confidence level.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011),
Paris, France, November 14-18 2011, 3 pages, 4 figure
Tree Level Unitarity Bounds for the Minimal B-L Model
We have derived the unitarity bounds in the high energy limit for the minimal
B-L extension of the Standard Model by analysing the full class of Higgs and
would-be Goldstone boson two-to-two scatterings at tree level. Moreover, we
have investigated how these limits could vary at some lower critical value of
the energy.Comment: 20 pages, 4 figures, 2 tables; 1d figure modified, typos corrected,
bibliography augmented; published in PRD after minor adjustmen
The Z' boson of the minimal B-L model at future Linear Colliders in e+e- --> mu+mu-
We study the capabilities of future electron-positron Linear Colliders, with
centre-of-mass energy at the TeV scale, in accessing the parameter space of a
boson within the minimal model. We carry out a detailed comparison
between the discovery regions mapped over a two-dimensional configuration space
( mass and coupling) at the Large Hadron Collider and possible future
Linear Colliders for the case of di-muon production. As known in the literature
for other models, we confirm that leptonic machines, as compared to the
CERN hadronic accelerator, display an additional potential in discovering a
boson as well as in allowing one to study its properties at a level of
precision well beyond that of any of the existing colliders.Comment: 5 pages, proceeding of LC09 (Perugia), published by the Italian
Physical Society in the Nuovo Cimento C (Colloquia
Gauge invariant effective action for the Polyakov line in the SU(N) Yang--Mills theory at high temperatures
We integrate out fast varying quantum fluctuations around static A_4 and A_i
fields for the SU(N) gauge group. By assuming that the gluon fields are slowly
varying but allowing for an arbitrary amplitude of A_4 we obtain two variants
of the effective high-temperature theory for the Polyakov line. One is the
effective action for the gauge-invariant eigenvalues of the Polyakov line, and
it is explicitly Z(N) symmetric. The other is the effective action for the
Polyakov line itself as an element of the SU(N). In this case the theory
necessarily includes the spatial components A_i to ensure its gauge invariance
under spatial gauge transformations. We derive the 1-loop effective action in
the `electric' and `magnetic' sectors, summing up all powers of A_4.Comment: RevTex4, 2 figure
Generalized Density Matrix Revisited: Microscopic Approach to Collective Dynamics in Soft Spherical Nuclei
The generalized density matrix (GDM) method is used to calculate
microscopically the parameters of the collective Hamiltonian. Higher order
anharmonicities are obtained consistently with the lowest order results, the
mean field [Hartree-Fock-Bogoliubov (HFB) equation] and the harmonic potential
[quasiparticle random phase approximation (QRPA)]. The method is applied to
soft spherical nuclei, where the anharmonicities are essential for restoring
the stability of the system, as the harmonic potential becomes small or
negative. The approach is tested in three models of increasing complexity: the
Lipkin model, model with factorizable forces, and the quadrupole plus pairing
model.Comment: submitted to Physical Review C on 08 May, 201
Strong Coupling Constants of Decuplet Baryons with Vector Mesons
We provide a comprehensive study of strong coupling constants of decuplet
baryons with light nonet vector mesons in the framework of light cone QCD sum
rules. Using the symmetry arguments, we argue that all coupling constants
entering the calculations can be expressed in terms of only one invariant
function even if the symmetry breaking effects are taken into
account. We estimate the order of symmetry violations, which are
automatically considered by the employed approach.Comment: 19 Pages, 4 Figures and 5 Table
Small size pentaquark width: calculation in QCD sum rules
The pentaquark width is calculated in QCD sum rules. The higher dimension
operators contribution is accounted. It is shown, that should
be very small, less than .Comment: 10 peges, 7 figure
Production of Z' and W' via Drell-Yan processes in the 4D Composite Higgs Model at the LHC
We present an analysis of both the Neutral Current (NC) and Charged Current
(CC) Drell-Yan processes at the LHC within a 4 Dimensional realization of a
Composite Higgs model studying the cross sections and taking into account the
possible impact of the extra fermions present in the spectrum.Comment: Conference proceeding, XII IFAE Edition, 3-5 April 2013, Cagliari. 2
pages, 2 figures; v2 typo correcte
Higgs Boson in the 4DCHM: LHC phenomenology
Composite Higgs models provide an elegant solution to the hierarchy problem
present in the Standard Model (SM) and give an alternative pattern leading to
the mechanism of Electro-Weak Symmetry Breaking (EWSB). We present an analysis
of the Higgs boson production and decay within a recently proposed realistic
realization of this general idea: the 4D Composite Higgs Model (4DCHM).
Comparing our results with the latest Large Hadron Collider (LHC) data we show
that the 4DCHM could provide an alternative explanation with respect to the SM
of the LHC results pointing to the discovery of a Higgs-like particle at 125
GeV.Comment: Conference proceeding, EPS-HEP 2013, 18-24 July 2013, Stockholm. 3
pages, 2 figures, typo correcte
Calculation of the pentaquark width by QCD sum rule
The pentaquark width is calculated in QCD sum rules. Result for
show, that can vary in the region less than
1. The main conclusion is, that if pentaquark is genuine states then sum
rules really predict the narrow width of pentaquark , and the
suppression of the width is both parametrical and numerical.Comment: 8 Ppages, 3 figures,the numerical error was corrected, two figures
are modified. In the limit of errors the result did not change significantl
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