403 research outputs found
Constraints on Mass Spectrum of Fourth Generation Fermions and Higgs Bosons
We reanalyze constraints on the mass spectrum of the chiral fourth generation
fermions and the Higgs bosons for the standard model (SM4) and the two Higgs
doublet model (THDM). We find that the Higgs mass in the SM4 should be larger
than roughly the fourth generation up-type quark mass, while the light CP even
Higgs mass in the THDM can be smaller. Various mass spectra of the fourth
generation fermions and the Higgs bosons are allowed. The phenomenology of the
fourth generation models is still rich.Comment: 15 pages, 16 figures; some points clarified, references added, to
appear in Phys.Rev.
A note on the coupling of the techni-dilaton to the weak bosons
In this note, we study the coupling of the techni-dilaton to the weak bosons.
We consider two cases: (1) The dilaton directly couples to the weak bosons
similarly to the SM. (2) The coupling in question is effectively induced only
through the techni-fermion loops. In both cases, we find that the coupling is
essentially determined by the mass-squared of the weak bosons over the dilaton
decay constant.Comment: 3 pages, 2 figures; minor changes, a reference added, to appear in
PR
Electrospray ionization mass spectrometric analysis of microcystins, cyclic heptapeptide hepatotoxins: modulation of charge states and [M + H]+ to [M + Na]+ ratio
AbstractElectrospray ionization mass spectrometry was used to develop a rapid, sensitive, and accurate method for determination and identification of hepatotoxic microcystins, cyanobacterial cyclic heptapeptides. To optimize the electrospray ionization conditions, factors affecting charge state distribution, such as amino acid components of sample, proton affinity of the additives, and additive concentration, were investigated in detail and a method for controlling charge states was developed to provide molecular-related ions for assignment of molecular weight and reasonably abundant precursor ions for MS/MS analysis. A procedure for identification of microcystins consisting of known amino acids was proposed: for microcystins giving abundant [M + 2H]2+ ions, the addition of nitrogen-containing bases to the aqueous sample solution is effective to obtain an increased intensity of [M + H]+ ions, whereas the addition of Lewis acids containing nitrogen can produce increased abundances of [M + 2H]2+ ions for microcystins giving weak [M + 2H]2+ ions. Microcystins possessing no arginine residue always give sodium adduct ions [M + Na]+ as the base peak, and these are difficult to fragment via low energy collision-induced dissociation to yield structurally informative products; the addition of oxalic acid increases [M + H]+ ion abundances, and these fragment readily
QKZ equation with |q|=1 and correlation functions of the XXZ model in the gapless regime
An integral solution to the quantum Knizhnik-Zamolodchikov (KZ) equation
with is presented. Upon specialization, it leads to a conjectural
formula for correlation functions of the XXZ model in the gapless regime. The
validity of this conjecture is verified in special cases, including the nearest
neighbor correlator with an arbitrary coupling constant, and general
correlators in the XXX and XY limits
Dynamics behind the quark mass hierarchy
We introduce a new class of models describing the quark mass hierarchy. In
this class, the dynamics primarily responsible for electroweak symmetry
breaking (EWSB) leads to the mass spectrum of quarks with no (or weak) isospin
violation. Moreover, the values of these masses are of the order of the
observed masses of the down-type quarks. Then, strong (although subcritical)
horizontal diagonal interactions for the quark plus horizontal
flavor-changing neutral interactions between different families lead (with no
fine tuning) to a realistic quark mass spectrum. In this scenario, many
composite Higgs bosons occur. A concrete model with the dynamical EWSB with the
fourth family is described in detail.Comment: 11 pages, 3 figures, v2: title shorten, references and 1 figure
added, text essentially extended, PRD versio
Extreme warming and regime shift toward amplified variability in a far northern lake
Mean annual air temperatures in the High Arctic are rising rapidly, with extreme warming events becoming increasingly common. Little is known, however, about the consequences of such events on the ice‐capped lakes that occur abundantly across this region. Here, we compared 2 years of high‐frequency monitoring data in Ward Hunt Lake in the Canadian High Arctic. One of the years included a period of anomalously warm conditions that allowed us to address the question of how loss of multi‐year ice cover affects the limnological properties of polar lakes. A mooring installed at the deepest point of the lake (9.7 m) recorded temperature, oxygen, chlorophyll a (Chl a ) fluorescence, and underwater irradiance from July 2016 to July 2018, and an automated camera documented changes in ice cover. The complete loss of ice cover in summer 2016 resulted in full wind exposure and complete mixing of the water column. This mixing caused ventilation of lake water heat to the atmosphere and 4°C lower water temperatures than under ice‐covered conditions. There were also high values of Chl a fluorescence, elevated turbidity levels and large oxygen fluctuations throughout fall and winter. During the subsequent summer, the lake retained its ice cover and the water column remained stratified, with lower Chl a fluorescence and anoxic bottom waters. Extreme warming events are likely to shift polar lakes that were formerly capped by continuous thick ice to a regime of irregular ice loss and unstable limnological conditions that vary greatly from year to year
Hidden Grassmann structure in the XXZ model V: sine-Gordon model
We study one-point functions of the sine-Gordon model on a cylinder. Our
approach is based on a fermionic description of the space of descendent fields,
developed in our previous works for conformal field theory and the sine-Gordon
model on the plane. In the present paper we make an essential addition by
giving a connection between various primary fields in terms of yet another kind
of fermions. The one-point functions of primary fields and descendants are
expressed in terms of a single function defined via the data from the
thermodynamic Bethe Ansatz equations.Comment: 36 pages. Some corrections are done in latest version, especially in
the subsection 10.
A quantum homogeneous space of nilpotent matrices
A quantum deformation of the adjoint action of the special linear group on
the variety of nilpotent matrices is introduced. New non-embedded quantum
homogeneous spaces are obtained related to certain maximal coadjoint orbits,
and known quantum homogeneous spaces are revisited.Comment: 12 page
Electrical properties of isotopically enriched neutron-transmutation-doped ^{70} Ge:Ga near the metal-insulator transition
We report the low temperature carrier transport properties of a series of
nominally uncompensated neutron-transmutation doped (NTD) ^{70} Ge:Ga samples
very close to the critical concentration N_c for the metal-insulator
transition. The concentration of the sample closest to N_c is 1.0004N_c and it
is unambiguously shown that the critical conductivity exponent is 0.5.
Properties of insulating samples are discussed in the context of Efros and
Shklovskii's variable range hopping conduction.Comment: 8 pages using REVTeX, 8 figures, published versio
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