2,028 research outputs found
PVLAS experiment, star cooling and BBN constraints: Possible interpretation with temperature dependent gauge symmetry breaking
It is known that the kinetic mixing of photon and another U(1)_ex gauge boson
can introduce millicharged particles. Millicharged particles of mass 0.1 eV
can explain the PVLAS experiment. We suggest a temperature dependent gauge
symmetry breaking of U(1)_ex for this idea to be consistent with astrophysical
and cosmological constraints.Comment: 9 pages, 3 figue
Neutrino oscillations in the Sun probe long-range leptonic forces
Lepton number charges might be the source of long range forces. If one
accepts that neutrinos produced in the Sun do indeed oscillate while crossing
the interior of the Sun, then the shift in the phase of the neutrino
wavefunction caused by an hypothetical potential associated to the leptonic
charge of the electrons in the Sun could affect the oscillation pattern beyond
what is actually observed. We show that a "fine structure" constant
in excess of is incompatible with present
observational data. This bound is not valid for forces whose range is shorter
than the size of the Sun.Comment: 6 pages, no figures. References adde
Dark Matter and Dark Radiation
We explore the feasibility and astrophysical consequences of a new long-range
U(1) gauge field ("dark electromagnetism") that couples only to dark matter,
not to the Standard Model. The dark matter consists of an equal number of
positive and negative charges under the new force, but annihilations are
suppressed if the dark matter mass is sufficiently high and the dark
fine-structure constant is sufficiently small. The correct relic
abundance can be obtained if the dark matter also couples to the conventional
weak interactions, and we verify that this is consistent with particle-physics
constraints. The primary limit on comes from the demand that the
dark matter be effectively collisionless in galactic dynamics, which implies
for TeV-scale dark matter. These values are
easily compatible with constraints from structure formation and primordial
nucleosynthesis. We raise the prospect of interesting new plasma effects in
dark matter dynamics, which remain to be explored.Comment: 14 pages, 6 figures Updated equations and figure
Neutrino Spin Flavor Precession and Leptogenesis
We argue that \Delta L=2 neutrino spin flavor precession, induced by the
primordial magnetic fields, could have a significant impact on the leptogenesis
process that accounts for the baryon asymmetry of the universe. Although the
extra galactic magnetic fields is extremely weak at present time (about 10^{-9}
Gauss), the primordial magnetic filed at the electroweak scale could be quite
strong (of order 10^{17} Gauss). Therefore, at this scale, the effects of the
spin flavor precession are not negligible. We show that the lepton asymmetry
may be reduced by 50% due to the spin flavor precession. In addition, the
leptogenesis will have different feature from the standard scenario of
leptogenesis, where the lepton asymmetry continues to oscillate even after the
electroweak phase transition.Comment: 5 pages, one figure. References adde
CP violation in unpolarized e^+ e^- to charginos at one loop level
We study CP violation in e^+ e^- to \tilde\chi_i^+\tilde\chi_j^- in the
framework of the MSSM. Though the cross section of this process is CP-even at
the tree level even for polarized electron-positron beams, we show that it
contains a CP-odd part at the one loop order and there are CP-odd observables
that can in principle be measured even using unpolarized electron-positron
beams. The relevant diagram calculations are briefly discussed and the results
of selected (box) diagram computations are shown.Comment: similar to Phys. Rev. D version, but corrected figs. 4, 5, 6 (factor
four
Constraints on flavor-dependent long range forces from solar neutrinos and KamLAND
Flavor-dependent long range (LR) leptonic forces, like those mediated by the
or gauge bosons, constitute a minimal extension of
the standard model that preserves its renormalizability. We study the impact of
such interactions on the solar neutrino oscillations when the interaction range
is much larger than the Earth-Sun distance. The LR potential can
dominate over the standard charged current potential inside the Sun in spite of
strong constraints on the coupling of the LR force coming from the
atmospheric neutrino data and laboratory search for new forces. We demonstrate
that the solar and atmospheric neutrino mass scales do not get trivially
decoupled even if is vanishingly small. In addition, for \alpha
\gsim 10^{-52} and normal hierarchy, resonant enhancement of
results in nontrivial energy dependent effects on the survival
probability. We perform a complete three generation analysis, and obtain
constraints on through a global fit to the solar neutrino and KamLAND
data. We get the limits and
when is much smaller than our
distance from the galactic center. With larger , the collective LR
potential due to all the electrons in the galaxy becomes significant and the
constraints on become stronger by upto two orders of magnitude.Comment: 25 pages, 7 figure
The relationship between hypergender ideology and rape empathy among male and female college students
The primary purpose of the present study was to examine the relationship between hypergender ideology and rape empathy. A sample of 157 college students completed a questionnaire packet containing demographic variables, the Hypergender Ideology Scale (HOS) and the Rape Empathy Scale (RES). It was predicted that those indicating stronger adherence to extreme stereotypic gender roles would report more empathy for the perpetrator rather than the victim of rape. It was also predicted that men would show stronger adherence to stereotypic gender roles and less victim empathy than women. Results show significant support for all predictions. Discussion involves implications that the link established between these constructs may contribute to the network of beliefs and attitudes that perpetuate rape in society
The decay eta_c^prime -> eta_c pi pi
It is pointed out that the decay of the recently observed charmonium
eta_c^prime resonance, eta_c^prime -> eta_c pi pi is simply related to the well
studied decay psi^prime -> J/psi pi pi and can thus be used for absolute
normalization of other decay modes of the eta_c^prime. The total rate of the
discussed decay should be approximately three to four times the corresponding
rate for the psi^prime$ resonance making the channel with charged pions the
most probable exclusive decay mode of the eta_c^prime with the branching ratio
in the range 5-10 %.Comment: 5 pages, references adde
Coulomb's law corrections from a gauge-kinetic mixing
We study the static quantum potential for a gauge theory which includes the
mixing between the familiar photon and a second massive gauge
field living in the so-called hidden-sector . Our discussion is carried
out using the gauge-invariant but path-dependent variables formalism, which is
alternative to the Wilson loop approach. Our results show that the static
potential is a Yukawa correction to the usual static Coulomb potential.
Interestingly, when this calculation is done inside a superconducting box, the
Coulombic piece disappears leading to a screening phase.Comment: 4 page
B_s(d) - bar B_s(d) mixing constraints on flavor changing decays of t and b quarks
We study those dimension 6 effective operators which generate flavor-changing
quark-gluon transitions of the third generation quarks, with t -> g + u(c) and
b -> g + d(s), and which could be of interest for LHC experiments. We analyze
the contribution of these operators to B_s(d) - bar B_s(d) mixing and derive
limits on the corresponding effective couplings from the existing experimental
data. The Standard Model gauge invariance relates these couplings to the
couplings controlling t -> g + u(c). On this basis we derive upper limits for
the branching ratios of these processes. We further show that forthcoming LHC
experiments might be able to probe the studied operators and the physics beyond
the Standard Model related to them.Comment: 6 pages, 1 figur
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