24 research outputs found
Radiative corrections to low energy neutrino reactions
We show that the radiative corrections to charged current (CC) nuclear
reactions with an electron(positron) in the final state are described by a
universal function. The consistency of our treatment of the radiative
corrections with the procedure used to extract the value of the axial coupling
constant is discussed. To illustrate we apply our results to
(anti)neutrino deuterium disintegration and to fusion in the sun. The
limit of vanishing electron mass is considered, and a simple formula valid for
E_{obs}\gsim 1 MeV is obtained. The size of the nuclear structure-dependent
effects is also discussed. Finally, we consider CC transitions with an
electron(positron) in the initial state and discuss some applications to
electron capture reactions.Comment: 23 pages, 5 figure
The Weak Charge of the Proton and New Physics
We address the physics implications of a precision determination of the weak
charge of the proton, QWP, from a parity violating elastic electron proton
scattering experiment to be performed at the Jefferson Laboratory. We present
the Standard Model (SM) expression for QWP including one-loop radiative
corrections, and discuss in detail the theoretical uncertainties and missing
higher order QCD corrections. Owing to a fortuitous cancellation, the value of
QWP is suppressed in the SM, making it a unique place to look for physics
beyond the SM. Examples include extra neutral gauge bosons, supersymmetry, and
leptoquarks. We argue that a QWP measurement will provide an important
complement to both high energy collider experiments and other low energy
electroweak measurements. The anticipated experimental precision requires the
knowledge of the order alpha_s corrections to the pure electroweak box
contributions. We compute these contributions for QWP, as well as for the weak
charges of heavy elements as determined from atomic parity violation.Comment: 22 pages of LaTeX, 5 figure
Limits on the monopole magnetic field from measurements of the electric dipole moments of atoms, molecules and the neutron
A radial magnetic field can induce a time invariance violating electric
dipole moment (EDM) in quantum systems. The EDMs of the Tl, Cs, Xe and Hg atoms
and the neutron that are produced by such a field are estimated. The
contributions of such a field to the constants, of the T,P-odd
interactions and are also estimated for the TlF, HgF and YbF molecules (where
() is the electron (nuclear) spin and is the molecular
axis). The best limit on the contact monopole field can be obtained from the
measured value of the Tl EDM. The possibility of such a field being produced
from polarization of the vacuum of electrically charged magnetic monopoles
(dyons) by a Coulomb field is discussed, as well as the limit on these dyons.
An alternative mechanism involves chromomagnetic and chromoelectric fields in
QCD.Comment: Uses RevTex, 16 pages, 4 postscript figures. An explanation of why
there is no orbital contribution to the EDM has been added, and the
presentation has been improved in genera
The Electroweak Chiral Lagrangian and CP-Violating Effects in Technicolor Theories
We estimate the CP-violating and anomalous form factors,
arising from CP-violating interactions in extended technicolor theories, and
discuss their future experimental detectability. The electric dipole moment of
the boson is found to be as large as {\cal O}(10^{-21}) \; \mbox{e cm}.
We connect the CP-odd and couplings to the corresponding
CP-violating electroweak chiral lagrangian operators. The electric dipole
moments of the neutron and the electron in technicolor theories are estimated
to be as large as {\cal O}(10^{-26}) \; \mbox{e cm} and {\cal O}(10^{-29})
\; \mbox{e cm} respectively. We also suggest the potential to observe large
CP-violating technicolor effects in the decay .Comment: 34 pages, YCTP-P9-94, LaTex. (minor changes in wording and notation,
the figures are appended at the end as one postscript file
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
Physics with the KLOE-2 experiment at the upgraded DANE
Investigation at a --factory can shed light on several debated issues
in particle physics. We discuss: i) recent theoretical development and
experimental progress in kaon physics relevant for the Standard Model tests in
the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum
Mechanics from time evolution of entangled kaon states, iii) the interest for
improving on the present measurements of non-leptonic and radiative decays of
kaons and eta/eta mesons, iv) the contribution to understand the
nature of light scalar mesons, and v) the opportunity to search for narrow
di-lepton resonances suggested by recent models proposing a hidden dark-matter
sector. We also report on the physics in the continuum with the
measurements of (multi)hadronic cross sections and the study of gamma gamma
processes.Comment: 60 pages, 41 figures; added affiliation for one of the authors; added
reference to section