2,525 research outputs found
LHC Search of New Higgs Boson via Resonant Di-Higgs Production with Decays into 4W
Searching for new Higgs particle beyond the observed light Higgs boson
h(125GeV) will unambiguously point to new physics beyond the standard model. We
study the resonant production of a CP-even heavy Higgs state in the
di-Higgs channel via, , at the LHC Run-2 and
the high luminosity LHC (HL-LHC). We analyze two types of the decay modes,
one with the same-sign di-leptons () and the
other with tri-leptons (). We
perform a full simulation for the signals and backgrounds, and estimate the
discovery potential of the heavy Higgs state at the LHC Run-2 and the HL-LHC,
in the context of generical two-Higgs-doublet models (2HDM). We determine the
viable parameter space of the 2HDM as allowed by the theoretical constraints
and the current experimental limits. We systematically analyze the allowed
parameter space of the 2HDM which can be effectively probed by the heavy Higgs
searches of the LHC, and further compare this with the viable parameter region
under the current theoretical and experimental bounds.Comment: v3: JHEP published version, 34pp, 10 Figs(36 plots) and 9 Tables.
Only minor typos fixed, references added. v2: JHEP version. All results and
conclusions un-changed, discussions and references added. (This update is
much delayed due to author's traveling and flu.
Mapping the Asymmetric Thick Disk: II Distance, Size and Mass of the Hercules Thick Disk Cloud
The Hercules Thick Disk Cloud (Larsen et al. 2008) was initially discovered
as an excess in the number of faint blue stars between quadrants 1 and 4 of the
Galaxy. The origin of the Cloud could be an interaction with the disk bar, a
triaxial thick disk or a merger remnant or stream. To better map the spatial
extent of the Cloud along the line of sight, we have obtained multi-color UBVR
photometry for 1.2 million stars in 63 fields approximately 1 square degree
each. Our analysis of the fields beyond the apparent boundaries of the excess
have already ruled out a triaxial thick disk as a likely explanation (Larsen,
Humphreys and Cabanela 2010) In this paper we present our results for the star
counts over all of our fields, determine the spatial extent of the over density
across and along the line of sight, and estimate the size and mass of the
Cloud. Using photometric parallaxes, the stars responsible for the excess are
between 1 and 6 kiloparsecs from the Sun, 0.5 -- 4 kpc above the Galactic
plane, and extends approximately 3-4 kiloparsecs across our line of sight. It
is thus a major substructure in the Galaxy. The distribution of the excess
along our sight lines corresponds with the density contours of the bar in the
Disk, and its most distant stars are directly over the bar. We also see through
the Cloud to its far side. Over the entire 500 square degrees of sky containing
the Cloud, we estimate more than 5.6 million stars and 1.9 million solar masses
of material. If the over density is associated with the bar, it would exceed
1.4 billion stars and more than than 50 million solar masses. Finally, we argue
that the Hercules-Aquila Cloud (Belokurov et al. 2007) is actually the Hercules
Thick Disk Cloud.Comment: 52 pages, 13 figure
Mapping the Asymmetric Thick Disk I. A Search for Triaxiality
A significant asymmetry in the distribution of faint blue stars in the inner
Galaxy, Quadrant 1 (l = 20 to 45 degrees) compared to Quadrant 4 was first
reported by Larsen & Humphreys (1996). Parker et al (2003, 2004) greatly
expanded the survey to determine its spatial extent and shape and the
kinematics of the affected stars. This excess in the star counts was
subsequently confirmed by Juric et al. (2008) using SDSS data. Possible
explanations for the asymmetry include a merger remnant, a triaxial Thick Disk,
and a possible interaction with the bar in the Disk. In this paper we describe
our program of wide field photometry to map the asymmetry to fainter magnitudes
and therefore larger distances. To search for the signature of triaxiality, we
extended our survey to higher Galactic longitudes. We find no evidence for an
excess of faint blue stars at l > 55 degrees including the faintest magnitude
interval. The asymmetry and star count excess in Quadrant 1 is thus not due to
a triaxial Thick Disk.Comment: 36 pages, 8 figures. Accepted by Astronomical Journa
Covariance of Weak Lensing Observables
Analytical expressions for covariances of weak lensing statistics related to
the aperture mass \Map are derived for realistic survey geometries such as
SNAP for a range of smoothing angles and redshift bins. We incorporate the
contributions to the noise due to the intrinsic ellipticity distribution and
the effects of finite size of the catalogue. Extending previous results to the
most general case where the overlap of source populations is included in a
complete analysis of error estimates, we study how various angular scales in
various redshifts are correlated and how the estimation scatter changes with
survey parameters. Dependence on cosmological parameters and source redshift
distributions are studied in detail. Numerical simulations are used to test the
validity of various ingredients to our calculations. Correlation coefficients
are defined in a way that makes them practically independent of cosmology. They
can provide important tools to cross-correlate one or more different surveys,
as well as various redshift bins within the same survey or various angular
scales from same or different surveys. Dependence of these coefficients on
various models of underlying mass correlation hierarchy is also studied.
Generalisations of these coefficients at the level of three-point statistics
have the potential to probe the complete shape dependence of the underlying
bi-spectrum of the matter distribution. A complete error analysis incorporating
all sources of errors suggest encouraging results for studies using future
space based weak lensing surveys such as SNAP.Comment: 14 pages, 10 Figures, Submitted to MNRA
Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disk ejecta from neutron star mergers
We investigate the nucleosynthesis of heavy elements in the winds ejected by
accretion disks formed in neutron star mergers. We compute the element
formation in disk outflows from hypermassive neutron star (HMNS) remnants of
variable lifetime, including the effect of angular momentum transport in the
disk evolution. We employ long-term axisymmetric hydrodynamic disk simulations
to model the ejecta, and compute r-process nucleosynthesis with tracer
particles using a nuclear reaction network containing species. We
find that the previously known strong correlation between HMNS lifetime,
ejected mass, and average electron fraction in the outflow is directly related
to the amount of neutrino irradiation on the disk, which dominates mass
ejection at early times in the form of a neutrino-driven wind. Production of
lanthanides and actinides saturates at short HMNS lifetimes ( ms),
with additional ejecta contributing to a blue optical kilonova component for
longer-lived HMNSs. We find good agreement between the abundances from the disk
outflow alone and the solar r-process distribution only for short HMNS
lifetimes ( ms). For longer lifetimes, the rare-earth and third
r-process peaks are significantly under-produced compared to the solar pattern,
requiring additional contributions from the dynamical ejecta. The
nucleosynthesis signature from a spinning black hole (BH) can only overlap with
that from a HMNS of moderate lifetime ( ms). Finally, we show that
angular momentum transport not only contributes with a late-time outflow
component, but that it also enhances the neutrino-driven component by moving
material to shallower regions of the gravitational potential, in addition to
providing additional heating.Comment: 18 pages, 11 figures, published version with small change
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
Monotone Concave Operators: An application to the existence and uniqueness of solutions to the Bellman equation
We propose a new approach to the issue of existence and uniqueness of solutions to the Bellman equation, exploiting an emerging class of methods, called monotone map methods, pioneered in the work of Krasnosel'skii-Zabreiko (1984). The approach is technically simple and intuitive. It is derived from geometric ideas related to the study of fixed points for monotone concave operators defined on partially order spaces.Dynamic programming; Bellman equation; Unbounded returns
Iridoid glucosides from Pentas lanceolata (Forssk.) Deflers growing on the Island of Sardinia
The ethanolic extract of Pentas lanceolata (Forssk.) Deflers was investigated from a phytochemical point of view and in particular on the monoterpenoid glucosides content. Iridoid glucosides have a taxonomic relevance, e.g., asperuloside and its derivative are characteristic of the Rubioideae subfamily where this species is comprised. In the light of earliest phylogenetic molecular study which proposed to merge P. lanceolata in the Spermacoceae tribe, a phytochemical approach also becomes necessary for a correct classification of this species. A total of 12 compounds were identified in detail, ten of these are iridoid glucosides: asperuloside, asperulosidic acid, tudoside, E-uenfoside and Z-uenfoside previously identified in this genus; whereas, deacetyl-asperulosidic acid, ixoside, griselinoside, 6β,7β-epoxysplendoside were recognized here for the first time from P. lanceolata. Among the non-iridoidic compounds ursolic acid and d-xylose were identified
The CKM matrix with maximal CP violation from Z(12) symmetry
The recent accurate determination of the CKM parameters including the maximal
CP phase 90 degrees enables us to write down the up-type and down-type quark
mass matrices to a high degree of accuracy. The lightest element(the uu
element) of the quark mass texture (not the mass eigenvalue) has a power
lambda**6 where lambda=sin(Cabibbo angle). The CP phase of 360 degrees divided
by an integer hints a discrete symmetry. Since lambda**6 is the highest power
among the quark mass matrix elements, we present as an example a possibility
that the maximal CP phase 90 degrees is obtainable from a supersymmetric Z(12)
discrete symmetry model.Comment: 7 pages of LaTeX file. No figur
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