15,583 research outputs found
Footprints of SUSY GUTs in Flavour Physics
Supersymmetric (SUSY) Grand Unified theories (GUTs) generally predict FCNC
and CP violating processes to occur both in the leptonic and hadronic sectors.
Assuming an underlying SU(5) group plus right-handed neutrinos (RN), we perform
an extensive study of FCNC and CP violation, analyzing the correlations between
leptonic and hadronic processes like mu-> e gamma and K-Kbar mixing, tau->mu
gamma and b -> s transitions such as B_d -> phi K_s and Bs-Bsbar mixing.
Moreover, we examine the impact of the considered scenario on the UT analyses,
monitoring the low energy consequences implied by possible solutions to the
various tensions in the present UT analyses. We compare the phenomenological
implications of this NP scenario with the ones of supersymmetric flavour models
finding a few striking differences that could allow to distinguish these
different NP models.Comment: 15 pages, 4 figure
A New Robust Low-Scatter X-ray Mass Indicator for Clusters of Galaxies
We present comparison of X-ray proxies for the total cluster mass, including
the spectral temperature (Tx), gas mass measured within r500 (Mg), and the new
proxy, Yx, which is a simple product of Tx and Mg and is related to the total
thermal energy of the ICM. We use mock Chandra images constructed for a sample
of clusters simulated with the eulerian N-body+gasdynamics adaptive mesh
refinement ART code in the concordance LCDM cosmology. The simulations achieve
high spatial and mass resolution and include radiative cooling, star formation,
and other processes accompanying galaxy formation. Our analysis shows that
simulated clusters exhibit a high degree of regularity and tight correlations
between the considered observables and total mass. The normalizations of the
M-Tx, Mg-Tx, and M-Yx relations agree to better than 10-15% with the current
observational measurements of these relations. Our results show that Yx is the
best mass proxy with a remarkably low scatter of only ~5-7% in M500 for a fixed
Yx, at both low and high redshifts and regardless of whether clusters are
relaxed or not. In addition, we show that redshift evolution of the Yx-M500
relation is close to the self-similar prediction, which makes Yx a very
attractive mass indicator for measurements of the cluster mass function from
X-ray selected samples.Comment: submitted to ApJ; 9 pages, 6 figures, uses emulateap
Missing Thermal Energy of the Intracluster Medium
The Sunyaev-Zel'dovich (SZ) effect is a direct probe of thermal energy
content of the Universe, induced in the cosmic microwave background (CMB) sky
through scattering of CMB photons off hot electrons in the intracluster medium
(ICM). We report a 9-sigma detection of the SZ signal in the CMB maps of
Wilkinson Microwave Anisotropy Probe (WMAP) 3yr data, through study of a sample
of 193 massive galaxy clusters with observed X-ray temperatures greater than 3
keV. For the first time, we make a model-independent measurement of the
pressure profile in the outskirts of the ICM, and show that it closely follows
the profiles obtained by X-ray observations and numerical simulations. We find
that our measurements of the SZ effect would account for only half of the
thermal energy of the cluster, if all the cluster baryons were in the hot ICM
phase. Our measurements indicate that a significant fraction (35 +/- 8 %) of
baryonic mass is missing from the hot ICM, and thus must have cooled to form
galaxies, intracluster stars, or an unknown cold phase of the ICM. There does
not seem to be enough mass in the form of stars or cold gas in the cluster
galaxies or intracluster space, signaling the need for a yet-unknown baryonic
component (at 3-sigma level), or otherwise new astrophysical processes in the
ICM.Comment: 9 pages, 4 figures, references added, a mismatch between X-ray and SZ
properties of simulated clusters is corrected, marginally increasing the
significance of missing baryon fraction, Accepted for publication in MNRA
The Radial Distribution of Galaxies in LCDM clusters
We study the radial distribution of subhalos and galaxies using
high-resolution cosmological simulations of galaxy clusters formed in the
concordance LCDM cosmology. In agreement with previous studies, we find that
the radial distribution of subhalos is significantly less concentrated than
that of the dark matter, when subhalos are selected using their present-day
gravitationally bound mass. We show that the difference in the radial
distribution is not a numerical artifact and is due to tidal stripping. The
subhalos in the cluster core lose more than 70% of their initial mass since
accretion, while the average tidal mass loss for halos near the virial radius
is ~30%. This introduces a radial bias in the spatial distribution of subhalos
when they are selected using their tidally truncated mass. We demonstrate that
the radial bias disappears almost entirely if subhalos are selected using their
mass or circular velocity at the accretion epoch. The comparisons of the
results of dissipationless simulations to the observed distribution of galaxies
in clusters are therefore sensitive to the selection criteria used to select
subhalo samples. Using the simulations that include cooling and starformation,
we show that the radial distribution of subhalos is in reasonable agreement
with the observed radial distribution of galaxies in clusters for
0.1<R/R200<2.0, if subhalos are selected using the stellar mass of galaxies.
The radial bias is minimized in this case because the stars are located in the
centers of dark matter subhalos and are tightly bound. The stellar mass of an
object is therefore approximately conserved as the dark matter is stripped from
the outer regions. Nevertheless, the concentration of the radial distribution
of galaxies is systematically lower than that of the dark matter.Comment: submitted to ApJ, 12 pages, 12 figure
Phase structure and Higgs boson mass in a Higgs-Yukawa model with a dimension-6 operator
We investigate the impact of a term included in a
chirally invariant lattice Higgs-Yukawa model. Such a term could emerge from
BSM physics at some larger energy scale. We map out the phase structure of the
Higgs-Yukawa model with positive and negative quartic self coupling
of the scalar fields. To this end, we evaluate the constraint effective
potential in lattice perturbation theory and also determine the magnetization
of the model via numerical simulations which allow us to reach also
non-perturbative values of the couplings. As a result, we find a complex phase
structure with first and second order phase transitions identified through the
magnetization. Further we analyze the effect of such a term on the
lower Higgs boson mass bound to see, whether the standard model lower mass
bound can be altered.Comment: proceedings for The 32nd International Symposium on Lattice Field
Theor
Multiple peak aggregations for the Keller-Segel system
In this paper we derive matched asymptotic expansions for a solution of the
Keller-Segel system in two space dimensions for which the amount of mass
aggregation is , where Previously available asymptotics
had been computed only for the case in which N=1
Ablation of smooth muscle myosin heavy chain SM2 increases smooth muscle contractility and results in postnatal death in mice
The smooth muscle myosin heavy chains (SMHC) are motor proteins powering smooth muscle contraction. Alternate splicing of SHMC gene at the C-terminus produces SM1, and SM2 myosin isoforms; SM2 (200 kDa) contains a unique 9-amino-acid sequence at the carboxyl terminus, whereas SM1 (204 kDa) has a 43 amino acid non-helical tail region. To date the functional difference between C-terminal isoforms has not been established; therefore, we used an exon-specific gene targeting strategy and generated a mouse model specifically deficient in SM2. Deletion of exon-41 of the SMHC gene resulted in a complete loss of SM2 in homozygous (_SM2^-/-^_) mice, accompanied by a concomitant down-regulation of SM1 in bladders. While heterozygous (_SM2^+/-^_) mice appeared normal and fertile, _SM2^-/-^_ mice died within 30 days after birth. The peri-mortal _SM2^-/-^_ mice showed reduced body weight, distention of the bladder and alimentary tract, and end-stage hydronephrosis. Interestingly, strips from _SM2^-/-^_ bladders showed increased contraction to K^+^ depolarization or M3 receptor activation. These results suggest that SM2 myosin has a distinct functional role in smooth muscle, and the deficiency of SM2 increases smooth muscle contractility, and causes dysfunctions of smooth muscle organs, including the bladder that leads to the end-stage hydronephrosis and postnatal death
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