72 research outputs found
Cosmic Acceleration and the Helicity-0 Graviton
We explore cosmology in the decoupling limit of a non-linear covariant
extension of Fierz-Pauli massive gravity obtained recently in arXiv:1007.0443.
In this limit the theory is a scalar-tensor model of a unique form defined by
symmetries. We find that it admits a self-accelerated solution, with the Hubble
parameter set by the graviton mass. The negative pressure causing the
acceleration is due to a condensate of the helicity-0 component of the massive
graviton, and the background evolution, in the approximation used, is
indistinguishable from the \Lambda CDM model. Fluctuations about the
self-accelerated background are stable for a certain range of parameters
involved. Most surprisingly, the fluctuation of the helicity-0 field above its
background decouples from an arbitrary source in the linearized theory. We also
show how massive gravity can remarkably screen an arbitrarily large
cosmological constant in the decoupling limit, while evading issues with
ghosts. The obtained static solution is stable against small perturbations,
suggesting that the degravitation of the vacuum energy is possible in the full
theory. Interestingly, however, this mechanism postpones the Vainshtein effect
to shorter distance scales. Hence, fifth force measurements severely constrain
the value of the cosmological constant that can be neutralized, making this
scheme phenomenologically not viable for solving the old cosmological constant
problem. We briefly speculate on a possible way out of this issue.Comment: v2: improved discussion and referencin
Effect of Surface Phenomena on Selective Separation Properties of Liquid Crystal Stationary Phase
The present work deals with the study on the distribution of contribution of adsorption and dissolution to retention volume of individual components in gas-liquid chromatography as dependent on the amount of liquid crystal stationary phase deposited on solid support and on the chromatographic column temperature.Досліджено розподіл внесків адсорбції і розчинення в утримуваний об'єм окремих компонентів у газорідинної хроматографії в залежності від кількості нанесеної на твердий носій рідкокристалічною нерухомої фази і температури нагріву хроматографічної колонки.Исследовано распределение вкладов адсорбции и растворения в удерживаемый объём отдельных компонентов в газо-жидкостной хроматографии в зависимости от количества нанесенной на твердый носитель жидкокристаллической неподвижной фазы и температуры нагрева хроматографической колонки
Effect of Surface Phenomena on Selective Separation Properties of Liquid Crystal Stationary Phase
The present work deals with the study on the distribution of contribution of adsorption and dissolution to retention volume of individual components in gas-liquid chromatography as dependent on the amount of liquid crystal stationary phase deposited on solid support and on the chromatographic column temperature.Досліджено розподіл внесків адсорбції і розчинення в утримуваний об'єм окремих компонентів у газорідинної хроматографії в залежності від кількості нанесеної на твердий носій рідкокристалічною нерухомої фази і температури нагріву хроматографічної колонки.Исследовано распределение вкладов адсорбции и растворения в удерживаемый объём отдельных компонентов в газо-жидкостной хроматографии в зависимости от количества нанесенной на твердый носитель жидкокристаллической неподвижной фазы и температуры нагрева хроматографической колонки
Combining Molecular Sieve and Complexing Properties of the Column Packing in Gas Chromatography
Influence of modifying pentasyl group synthetic zeolites (Silicalite-1 and Silicalite-2) with metal cations capable to specific interactions on the separation ability of the chromatographic column has been studied.Вивчено вплив модифікування синтетичних цеолітів сімейства пентасілів (Сілікаліту-1 і Сілікаліту-2) катіонами металів, здатних до специфічних взаємодій, на розділювальну здатність хроматографічної колонки.Изучено влияние модифицирования синтетических цеолитов семейства пентасилов (Силикалита-1 и Силикалита-2) катионами металлов, способными к специфическим взаимодействиям, на разделительную способность хроматографической колонки
A consistent picture for large penguins in D -> pi+ pi-, K+ K-
A long-standing puzzle in charm physics is the large difference between the
D0 -> K+ K- and D0 -> pi+ pi- decay rates. Recently, the LHCb and CDF
collaborations reported a surprisingly large difference between the direct CP
asymmetries, Delta A_CP, in these two modes. We show that the two puzzles are
naturally related in the Standard Model via s- and d-quark "penguin
contractions". Their sum gives rise to Delta A_CP, while their difference
contributes to the two branching ratios with opposite sign. Assuming nominal
SU(3) breaking, a U-spin fit to the D0 -> K+ pi-, pi+ K-, pi+ pi-, K+ K- decay
rates yields large penguin contractions that naturally explain Delta A_CP.
Expectations for the individual CP asymmetries are also discussed.Comment: 24 pages, 8 figure
Nonlinear Dynamics of 3D Massive Gravity
We explore the nonlinear classical dynamics of the three-dimensional theory
of "New Massive Gravity" proposed by Bergshoeff, Hohm and Townsend. We find
that the theory passes remarkably highly nontrivial consistency checks at the
nonlinear level. In particular, we show that: (1) In the decoupling limit of
the theory, the interactions of the helicity-0 mode are described by a single
cubic term -- the so-called cubic Galileon -- previously found in the context
of the DGP model and in certain 4D massive gravities. (2) The conformal mode of
the metric coincides with the helicity-0 mode in the decoupling limit. Away
from this limit the nonlinear dynamics of the former is described by a certain
generalization of Galileon interactions, which like the Galileons themselves
have a well-posed Cauchy problem. (3) We give a non-perturbative argument based
on the presence of additional symmetries that the full theory does not lead to
any extra degrees of freedom, suggesting that a 3D analog of the 4D
Boulware-Deser ghost is not present in this theory. Last but not least, we
generalize "New Massive Gravity" and construct a class of 3D cubic order
massive models that retain the above properties.Comment: 21 page
Charming CP Violation and Dipole Operators from RS Flavor Anarchy
Recently the LHCb collaboration reported evidence for direct CP violation in
charm decays. The value is sufficiently large that either substantially
enhanced Standard Model contributions or non-Standard Model physics is required
to explain it. In the latter case only a limited number of possibilities would
be consistent with other existing flavor-changing constraints. We show that
warped extra dimensional models that explain the quark spectrum through flavor
anarchy can naturally give rise to contributions of the size required to
explain the the LHCb result. The D meson asymmetry arises through a sizable
CP-violating contribution to a chromomagnetic dipole operator. This happens
naturally without introducing inconsistencies with existing constraints in the
up quark sector. We discuss some subtleties in the loop calculation that are
similar to those in Higgs to \gamma\gamma. Loop-induced dipole operators in
warped scenarios and their composite analogs exhibit non-trivial dependence on
the Higgs profile, with the contributions monotonically decreasing when the
Higgs is pushed away from the IR brane. We show that the size of the dipole
operator quickly saturates as the Higgs profile approaches the IR brane,
implying small dependence on the precise details of the Higgs profile when it
is quasi IR localized. We also explain why the calculation of the coefficient
of the lowest dimension 5D operator is guaranteed to be finite. This is true
not only in the charm sector but also with other radiative processes such as
electric dipole moments, b to s\gamma, \epsilon'/\epsilon_K and \mu\ to
e\gamma. We furthermore discuss the interpretation of this contribution within
the framework of partial compositeness in four dimensions and highlight some
qualitative differences between the generic result of composite models and that
obtained for dynamics that reproduces the warped scenario.Comment: 14 page
Massive Spin-2 States as the Origin of the Top Quark Forward-Backward Asymmetry
We show that the anomalously large top quark forward-backward asymmetry
observed by CDF and D\O\, can naturally be accommodated in models with
flavor-violating couplings of a new massive spin-2 state to quarks. Regardless
of its origin, the lowest-order couplings of a spin-2 boson to fermions are
analogous to the coupling of the graviton to energy/momentum, leading to strong
sensitivity of the effects associated with its virtual exchange to the energy
scales at hand. Precisely due to this fact, the observed dependence of the
asymmetry on the invariant mass fits nicely into the proposed
framework. In particular, we find a vast parameter space which can lead to the
central value for the observed forward-backward asymmetry in the high mass bin,
while being in accord with all of the existing experimental constraints.Comment: added discussion of differential observables at the LHC, matches
version accepted for publication in JHE
Predictors of enhancing human physical attractiveness: Data from 93 countries
People across the world and throughout history have gone to great lengths to enhance their physical appearance. Evolutionary psychologists and ethologists have largely attempted to explain this phenomenon via mating preferences and strategies. Here, we test one of the most popular evolutionary hypotheses for beauty-enhancing behaviors, drawn from mating market and parasite stress perspectives, in a large cross-cultural sample. We also test hypotheses drawn from other influential and non-mutually exclusive theoretical frameworks, from biosocial role theory to a cultural media perspective. Survey data from 93,158 human participants across 93 countries provide evidence that behaviors such as applying makeup or using other cosmetics, hair grooming, clothing style, caring for body hygiene, and exercising or following a specific diet for the specific purpose of improving ones physical attractiveness, are universal. Indeed, 99% of participants reported spending >10 min a day performing beauty-enhancing behaviors. The results largely support evolutionary hypotheses: more time was spent enhancing beauty by women (almost 4 h a day, on average) than by men (3.6 h a day), by the youngest participants (and contrary to predictions, also the oldest), by those with a relatively more severe history of infectious diseases, and by participants currently dating compared to those in established relationships. The strongest predictor of attractiveness-enhancing behaviors was social media usage. Other predictors, in order of effect size, included adhering to traditional gender roles, residing in countries with less gender equality, considering oneself as highly attractive or, conversely, highly unattractive, TV watching time, higher socioeconomic status, right-wing political beliefs, a lower level of education, and personal individualistic attitudes. This study provides novel insight into universal beauty-enhancing behaviors by unifying evolutionary theory with several other complementary perspectives
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