240 research outputs found
Gluon Distribution Functions in the kT-factorization Approach
At small x, the effects of finite transverse momenta of partons inside a
hadron become increasingly important, especially in analyses of jets and
heavy-quark production. These effects can be systematically accounted for in a
formalism based on kT-factorization and unintegrated distribution functions. We
present results for the unintegrated distribution function, together with the
corresponding integrated one, obtained within the framework of the Linked
Dipole Chain model. Comparisons are made to results obtained within other
approaches
Equation of State for Exclusion Statistics in a Harmonic Well
We consider the equations of state for systems of particles with exclusion
statistics in a harmonic well. Paradygmatic examples are noninteracting
particles obeying ideal fractional exclusion statistics placed in (i) a
harmonic well on a line, and (ii) a harmonic well in the Lowest Landau Level
(LLL) of an exterior magnetic field. We show their identity with (i) the
Calogero model and (ii) anyons in the LLL of an exterior magnetic field and in
a harmonic well.Comment: latex file, 11 page
One Loop Renormalizability of Spontaneously Broken Gauge Theory with a Product of Gauge Groups on Noncommutative Spacetime: the U(1) x U(1) Case
A generalization of the standard electroweak model to noncommutative
spacetime would involve a product gauge group which is spontaneously broken.
Gauge interactions in terms of physical gauge bosons are canonical with respect
to massless gauge bosons as required by the exact gauge symmetry, but not so
with respect to massive ones; and furthermore they are generally asymmetric in
the two sets of gauge bosons. On noncommutative spacetime this already occurs
for the simplest model of U(1) x U(1). We examine whether the above feature in
gauge interactions can be perturbatively maintained in this model. We show by a
complete one loop analysis that all ultraviolet divergences are removable with
a few renormalization constants in a way consistent with the above structure.Comment: 24 pages, figures using axodraw; version 2: a new ref item [4] added
to cite efforts to all orders, typos fixed and minor rewordin
Flavor SU(3) analysis of charmless B meson decays to two pseudoscalar mesons
Global fits to charmless B --> PP decays in the framework of flavor SU(3)
symmetry are updated and improved without reference to the \sin2\beta measured
from the charmonium decay modes. Fit results directly constrain the
(\bar\rho,\bar\eta) vertex of the unitarity triangle, and are used to predict
the branching ratios and CP asymmetries of all decay modes, including those of
the B_s system. Different schemes of SU(3) breaking in decay amplitude sizes
are analyzed. The major breaking effect between strangeness-conserving and
strangeness-changing decays can be accounted for by including a ratio of decay
constants in tree and color-suppressed amplitudes. The possibility of having a
new physics contribution to K \pi decays is also examined from the data fitting
point of view.Comment: 22 pages and 2 figures; some comments and references added; more
references added, version to appear in journa
Chiral bosonization for non-commutative fields
A model of chiral bosons on a non-commutative field space is constructed and
new generalized bosonization (fermionization) rules for these fields are given.
The conformal structure of the theory is characterized by a level of the
Kac-Moody algebra equal to where is the
non-commutativity parameter and chiral bosons living in a non-commutative
fields space are described by a rational conformal field theory with the
central charge of the Virasoro algebra equal to 1. The non-commutative chiral
bosons are shown to correspond to a free fermion moving with a speed equal to where is the speed of light. Lorentz
invariance remains intact if is rescaled by . The
dispersion relation for bosons and fermions, in this case, is given by .Comment: 16 pages, JHEP style, version published in JHE
Vortices, Instantons and Branes
The purpose of this paper is to describe a relationship between the moduli
space of vortices and the moduli space of instantons. We study charge k
vortices in U(N) Yang-Mills-Higgs theories and show that the moduli space is
isomorphic to a special Lagrangian submanifold of the moduli space of k
instantons in non-commutative U(N) Yang-Mills theories. This submanifold is the
fixed point set of a U(1) action on the instanton moduli space which rotates
the instantons in a plane. To derive this relationship, we present a D-brane
construction in which the dynamics of vortices is described by the Higgs branch
of a U(k) gauge theory with 4 supercharges which is a truncation of the
familiar ADHM gauge theory. We further describe a moduli space construction for
semi-local vortices, lumps in the CP(N) and Grassmannian sigma-models, and
vortices on the non-commutative plane. We argue that this relationship between
vortices and instantons underlies many of the quantitative similarities shared
by quantum field theories in two and four dimensions.Comment: 32 Pages, 4 Figure
Quantum and Classical Ballistic Transport in Constricted Two-Dimensional Electron Gases
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Minimal Flavour Violation Waiting for Precise Measurements of Delta M_s, S_{psi phi}, A^s_SL, |V_ub|, gamma and B^0_{s,d} -> mu+ mu-
We emphasize that the recent measurements of the B^0_s - bar B^0_s mass
difference Delta M_s by the CDF and D0 collaborations offer an important model
independent test of minimal flavour violation (MFV). The improved measurements
of the angle gamma in the unitarity triangle and of |V_ub| from tree level
decays, combined with future accurate measurements of Delta M_s, S_{psi K_S},
S_{psi phi}, Br(B_{d,s} -> mu+ mu-), Br(B -> X_{d,s} nu bar nu), Br(K+ -> pi+
nu bar nu) and Br(K_L -> pi^0 nu bar nu) and improved values of the relevant
non-perturbative parameters, will allow to test the MFV hypothesis in a model
independent manner to a high accuracy. In particular, the difference between
the reference unitarity triangle obtained from tree level processes and the
universal unitarity triangle (UUT) in MFV models would signal either new
flavour violating interactions and/or new local operators that are suppressed
in MFV models with low tan(beta), with the former best tested through S_{psi
phi} and K_L -> pi^0 nu bar nu. A brief discussion of non-MFV scenarios is also
given. In this context we identify in the recent literature a relative sign
error between Standard Model and new physics contributions to S_{psi phi}, that
has an impact on the correlation between S_{psi phi} and A^s_SL. We point out
that the ratios S_{psi phi}/A^s_SL and (Delta M_s)/(Delta Gamma_s) will allow
to determine (Delta M_s)/(Delta M_s)^SM. Similar proposals for the
determination of (Delta M_d)/(Delta M_d)^SM are also given.Comment: 22 pages, 8 figures, 1 table. Extended discussion of the correlation
between S_{psi phi} and A^s_SL and new proposals to determine Delta
M_q/(Delta M_q)^SM from future measurements, with respect to the first
version. Minor changes and few references adde
Opportunities for Nebraska
The University of Nebraska is one of more than 100 land grant institutions in the United States and its territories. Although the University of Nebraska- Lincoln was the original campus of the University of Nebraska, the land grant mission extends to all four campuses of the University of Nebraska system. The land grant college system was established by the passage of the Morrill Act, which was signed into law on July 2, 1862 by President Abraham Lincoln. Named for Congressman Justin Smith Morrill of Vermont, the purpose of the Morrill Act was to establish a college in each state “where the leading object shall be, without excluding other scientific and classical studies, and including military tactics, to teach such branches of learning as are related to agriculture and the mechanic arts, in such manner as the legislatures of the states may respectively prescribe, in order to promote the liberal and practical education of the industrial classes in the several pursuits and professions in life.” The Morrill Act gave each state 30,000 acres of federal land for each sitting Senator and Representative in Congress, based on the 1860 census – thus the name “land grant.” The land grant system formed the framework for the land grant institutions’ missions of teaching, research and extension. Twenty-five years after the Morrill Act was passed, Congress passed the Hatch Act – on March 2, 1887. The Hatch Act established agricultural experiment stations in connection with the land grant colleges so research could be conducted and applied in practice. Named for Congressman William Henry Hatch of Missouri, the Hatch Act established not only experiment stations, but also distribution of information to the people of the United States on subjects connected with agriculture. The Hatch Act also provided an annual payment to each state and territory for the expenses of research, as well as for printing and distributing the results
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