871 research outputs found
Standard Model Higgs boson mass from inflation
We analyse one-loop radiative corrections to the inflationary potential in
the theory, where inflation is driven by the Standard Model Higgs field. We
show that inflation is possible provided the Higgs mass m_H lies in the
interval m_min<m_H<m_max, where m_min=[136.7+(m_t-171.2)*1.95]GeV,
m_max=[184.5+(m_t-171.2)*0.5]GeV and m_t is the mass of the top quark.
Moreover, the predictions of the spectral index of scalar fluctuations and of
the tensor-to-scalar ratio practically do not depend on the Higgs mass within
the admitted region and are equal to n_s=0.97 and r=0.0034 correspondingly.Comment: 5 pages, 3 figures. Journal version+misprint fixed and added
reference to the two-loop analysis paper for convenienc
Diagnostic Value Parameters Of Acute Phase Reactances Of Infectious-inflammatory Process In Diagnostics Of Early Neonatal Sepsis
An advanced progress of clinical neonatology in recent years has enabled to achieve considerable success in newborn management with due respect to both medical treatment and general care, especially in the group of neonates with low body weight at birth. At the same time, neonatal sepsis in the early period still predetermine sickness and mortality of newborns.Material and methods. Clinical-paraclinical indices with detection of diagnostic value of C-reactive protein and interleukins-6 and 8 were evaluated in 100 neonates with available susceptibility factors to early neonatal infection from mother\u27s side and clinical signs of organ dysfunction in neonates with precautions of generalized infectious-inflammatory process at the end of their first day of life.Results. The data obtained substantiate that low concentrations of IL-6 and IL-8 prevail, and therefore the mentioned mediators hardly can be used to verify early neonatal infection. In the majority of children C-reactive protein elevated the concentration of 10.0 mg/L which is traditionally considered to be a discriminant as to the verification of an infectious process in newborns.Conclusions. None of the clinical signs associated with infectious-inflammatory process in newborns in the first two days of their life enabled to verify reliably availability of systemic bacterial infection
Gauge singlet scalar as inflaton and thermal relic dark matter
We show that, by adding a gauge singlet scalar S to the standard model which
is nonminimally coupled to gravity, S can act both as the inflaton and as
thermal relic dark matter. We obtain the allowed region of the (m_s, m_h)
parameter space which gives a spectral index in agreement with observational
bounds and also produces the observed dark matter density while not violating
vacuum stability or nonperturbativity constraints. We show that, in contrast to
the case of Higgs inflation, once quantum corrections are included the spectral
index is significantly larger than the classical value (n = 0.966 for N = 60)
for all allowed values of the Higgs mass m_h. The range of Higgs mass
compatible with the constraints is 145 GeV < m_h < 170 GeV. The S mass lies in
the range 45 GeV < ms < 1 TeV for the case of a real S scalar with large
quartic self-coupling lambdas, with a smaller upper bound for smaller lambdas.
A region of the parameter space is accessible to direct searches at the LHC via
h-->SS, while future direct dark matter searches should be able to
significantly constrain the model.Comment: 13 pages, 7 figures. Published versio
Compact extra-dimensions as solution to the strong CP problem
We show that the strong CP problem can, in principle, be solved dynamically
by adding extra-dimensions with compact topology. To this aim we consider a toy
model for QCD, which contains a vacuum angle and a strong CP like problem. We
further consider a higher dimensional theory, which has a trivial vacuum
structure and which reproduces the perturbative properties of the toy model in
the low-energy limit. In the weak coupling regime, where our computations are
valid, we show that the vacuum structure of the low-energy action is still
trivial and the strong CP problem is solved. No axion-like particle occur in
this setup and therefore it is not ruled out by astrophysical bounds.Comment: Discussion adde
Magnetic field generation in Higgs inflation model
We study the generation of magnetic field in Higgs-inflation models where the
Standard Model Higgs boson has a large coupling to the Ricci scalar. We couple
the Higgs field to the Electromagnetic fields via a non- renormalizable
dimension six operator suppressed by the Planck scale in the Jordan frame. We
show that during Higgs inflation magnetic fields with present value
Gauss and comoving coherence length of can be generated in the
Einstein frame. The problem of large back-reaction which is generic in the
usual inflation models of magneto-genesis is avoided as the back-reaction is
suppressed by the large Higgs-curvature coupling.Comment: 10 pages, RevTeX
On the Naturalness of Higgs Inflation
We critically examine the recent claim that the Standard Model Higgs boson
could drive inflation in agreement with observations if has a strong coupling to the Ricci curvature scalar. We
first show that the effective theory approach upon which that claim is based
ceases to be valid beyond a cutoff scale , where is the
reduced Planck mass. We then argue that knowing the Higgs potential profile for
the field values relevant for inflation () requires knowledge of the ultraviolet completion of the SM beyond
. In absence of such microscopic theory, the extrapolation of the pure
SM potential beyond is unwarranted and the scenario is akin to other
ad-hoc inflaton potentials afflicted with significant fine-tuning. The
appealing naturalness of this minimal proposal is therefore lost.Comment: 9 pages. Replaced with published version, plus a footnote clarifying
the use of power counting estimate
Semiclassical Calculation of Multiparticle Scattering Cross Sections in Classicalizing Theories
It has been suggested in arXiv:1010.1415 that certain derivatively coupled
non-renormalizable scalar field theories might restore the perturbative
unitarity of high energy hard scatterings by classicalization, i.e. formation
of multiparticle states of soft quanta. Here we apply the semiclassical method
of calculating the multiparticle production rates to the scalar
Dirac-Born-Infeld (DBI) theory which is suggested to classicalize. We find that
the semiclassical method is applicable for the energies in the final state
above the cutoff scale of the theory L_*^{-1}. We encounter that the cross
section of the process two to N ceases to be exponentially suppressed for the
particle number in the final state N smaller than a critical particle number
N_{crit} ~ (E L_*)^{4/3}. It coincides with the typical particle number
produced in two-particle collisions at high energies predicted by
classicalization arguments.Comment: 17 pages, 4 figures, v2. Minor changes to match the published versio
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