6,885 research outputs found
Constraints on the Brans-Dicke gravity theory with the Planck data
Based on the new cosmic CMB temperature data from the Planck satellite, the 9
year polarization data from the WMAP, the BAO distance ratio data from the SDSS
and 6dF surveys, we place a new constraint on the Brans-Dicke theory. We adopt
a parametrization \zeta=\ln(1+1/\omega}), where the general relativity (GR)
limit corresponds to . We find no evidence of deviation from general
relativity. At 95% probability, , correspondingly,
the region is excluded. If we restrict ourselves to
the (i.e. ) case, then the 95% probability interval is
. We can also translate this
result to a constraint on the variation of gravitational constant, and find the
variation rate today as yr ( error bar), the integrated change since the epoch of
recombination is ( error
bar). These limits on the variation of gravitational constant are comparable
with the precision of solar system experiments.Comment: 7 pages, 5 figures, 2 table
Thermodynamics in the universe described by the emergence of the space and the energy balance relation
It has previously been shown that it is more general to describe the
evolution of the universe based on the emergence of the space and the energy
balance relation. Here we investigate the thermodynamic properties of the
universe described by such a model. We show that the first law of
thermodynamics and the generalized second law of thermodynamics (GSLT) are both
satisfied and the weak energy condition are also fulfilled for two typical
examples. Finally we examine the physical consistency for the present model.Comment: 9 pages, 2 figure
Transitions in the Standard Model Effective Field Theory
The anomalies observed in decays
have attracted much attention in recent years. In this paper, we study the
, , , , and decays, all
being mediated by the same quark-level transition, in the
Standard Model Effective Field Theory. The most relevant dimension-six
operators for these processes are , , ,
and in the Warsaw basis. Evolution of the corresponding Wilson
coefficients from the new physics scale ~TeV down to the
characteristic scale is performed at three-loop in QCD and
one-loop in EW/QED. It is found that, after taking into account the constraint
, a single
or
can still be used to resolve the
anomalies at , while a single
is already ruled out by the
measured at more than . By minimizing the
function constructed based on the current data on ,
, , , and , we obtain eleven most
trustworthy scenarios, each of which can provide a good explanation of the
anomalies at . To further discriminate these different
scenarios, we predict thirty-one observables associated with the processes
considered under each NP scenario. It is found that most of the scenarios can
be differentiated from each other by using these observables and their
correlations.Comment: 43 pages, 3 figures and 5 tables; references updated and more
discussions added, final version to be published in the journa
Revisiting the -physics anomalies in -parity violating MSSM
In recent years, several deviations from the Standard Model predictions in
semileptonic decays of -meson might suggest the existence of new physics
which would break the lepton-flavour universality. In this work, we have
explored the possibility of using muon sneutrinos and right-handed sbottoms to
solve these -physics anomalies simultaneously in -parity violating
minimal supersymmetric standard model. We find that the photonic penguin
induced by exchanging sneutrino can provide sizable lepton flavour universal
contribution due to the existence of logarithmic enhancement for the first
time. This prompts us to use the two-parameter scenario to explain anomaly. Finally, the
numerical analyses show that the muon sneutrinos and right-handed sbottoms can
explain and anomalies simultaneously,
and satisfy the constraints of other related processes, such as decays, mixing, decays, as well as
, , , , , , and decays.Comment: 10 pages, 8 figures, matches to the version published in EPJ
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