1,827 research outputs found
CP Violation in D0 - anti-D0 Oscillations: General Considerations and Applications to the Littlest Higgs Model with T-Parity
The observed D0 - anti-D0 oscillations provide a new stage in our search for
New Physics in heavy flavour dynamics. The theoretical verdict on the observed
values of x_D and y_D remains ambiguous: while they could be totally generated
by Standard Model dynamics, they could also contain a sizable or even leading
contribution from New Physics. Those oscillations are likely to enhance the
observability of CP violation as clear manifestations of New Physics. We
present general formulae for D0 - anti-D0 oscillations, concentrating on the
case of negligible direct CP violation. In particular we derive a general
formula for the time-dependent mixing-induced CP asymmetry in decays to a CP
eigenstate and its correlation with the semileptonic CP asymmetry a_SL(D0) in
D0(t) -> l nu K. We apply our formalism to the Littlest Higgs model with
T-parity, using the time-dependent CP asymmetry in D -> K_S phi as an example.
We find observable effects at a level well beyond anything possible with CKM
dynamics. Comparisons with CP violation in the K and B systems offer an
excellent test of this scenario and reveal the specific pattern of flavour and
CP violation in the D0 - anti-D0 system predicted by this model. We discuss a
number of charm decays that could potentially offer an insight in the dynamics
of CP violation in D decays. We also apply our formalism to B_s - anti-B_s
mixing.Comment: 26 pages, 9 png figures, 1 table. v2: eq. (A.1) corrected, minor
clarifying comments and few references added. v3: typos corrected, matches
published versio
Rare K and B Decays in a Warped Extra Dimension with Custodial Protection
We present a complete study of rare K and B meson decays in a warped extra
dimensional model with a custodial protection of (both diagonal and
non-diagonal) Z d_L^i \bar d_L^j couplings, including K^+ -> pi^+ nu anti-nu,
K_L -> pi^0 nu anti-nu, K_L -> pi^0 l^+ l^-, K_L -> mu^+ mu^-, B_{s,d} -> mu^+
mu^-, B -> K nu anti-nu, B -> K^* nu anti-nu and B -> X_{s,d} nu anti-nu. In
this model in addition to Standard Model one loop contributions these processes
receive tree level contributions from the Z boson and the new heavy electroweak
gauge bosons. We analyse all these contributions that turn out to be dominated
by tree level Z boson exchanges governed by right-handed couplings to down-type
quarks. Imposing all existing constraints from Delta F=2 transitions analysed
by us recently and fitting all quark masses and CKM mixing parameters we find
that a number of branching ratios for rare K decays can differ significantly
from the SM predictions, while the corresponding effects in rare B decays are
modest, dominantly due to the custodial protection being more effective in B
decays than in K decays. In order to reduce the parameter dependence we study
correlations between various observables within the K system, within the B
system and in particular between K and B systems, and also between Delta F=2
and Delta F=1 observables. These correlations allow for a clear distinction
between this new physics scenario and models with minimal flavour violation or
the Littlest Higgs Model with T-parity, and could give an opportunity to future
experiments to confirm or rule out the model. We show how our results would
change if the custodial protection of Z d_L^i bar d^j_L couplings was absent.
In the case of rare B decays the modifications are spectacular.Comment: 50 pages, 17 figures. v2: minor clarifying comments and references
added. v3: few clarifying comments added, matches published versio
Bad Religion: How Ex-Mormon Fiction Reinforces Normative Views of American Religion
This project examines recent fiction by ex-Mormon authors and highlights how these novels reinforce an American ideal of “good religion.” These texts reveal the boundaries of American religious freedom by illustrating examples of “bad religion” and providing favorable alternatives. The paper looks at scholarship on 19th century anti-Mormon literature, which provides a foundation for the more modern literature at hand. Through the recent narratives, authors point to an abstract concept of benign, acceptable religion, marking as harmful that which does not share these key characteristics. While these fictional sects appear differently in each work, they comment on similar themes, such as the threat of rigid authority structures and figures, community isolation and insulation, coercive proselytizing and manipulation, and an emphasis on escaping the sect. These themes highlight the existence of a particular brand of American “good religion,” which is antithetical to such groups illustrated in these texts
The Impact of a 4th Generation on Mixing and CP Violation in the Charm System
We study D0-D0 mixing in the presence of a fourth generation of quarks. In
particular, we calculate the size of the allowed CP violation which is found at
the observable level well beyond anything possible with CKM dynamics. We
calculate the semileptonic asymmetry a_SL and the mixing induced CP asymmetry
eta_fS_f which are correlated with each other. We also investigate the
correlation of eta_fS_f with a number of prominent observables in other mesonic
systems like epsilon'/epsilon, Br(K_L -> pi0 nu nu), Br(K+ -> pi+ nu nu),
Br(B_s ->mu+ mu-), Br(B_d -> mu+ mu-) and finally S_psi phi in the B_s system.
We identify a clear pattern of flavour and CP violation predicted by the SM4
model: While simultaneous large 4G effects in the K and D systems are possible,
accompanying large NP effects in the B_d system are disfavoured. However this
behaviour is not as pronounced as found for the LHT and RSc models. In contrast
to this, sizeable CP violating effects in the B_s system are possible unless
extreme effects in eta_fS_f are found, and Br(B_s ->mu+ mu-) can be strongly
enhanced regardless of the situation in the D system. We find that, on the
other hand, S_psi phi > 0.2 combined with the measured epsilon'/epsilon
significantly diminishes 4G effects within the D system.Comment: 22 pages, 23 figures, v2 (references added
Indirect tests of the Randall-Sundrum model
I present phenomenological implications of the Randall-Sundrum model for
indirect searches, specifically a selection of flavor observables and
Higgs-related collider searches. I review the interplay of constraints from CP
violation in flavor physics, possible effects in rare decays, and
model-specific protection mechanisms. Deviations in the Higgs couplings to
fermions and, at one-loop, to gluons are unexpectedly strong and lead to strong
modifications in Higgs searches.Comment: 8 pages, 6 figures; Talk given at Discrete '10: Symposium on
Prospects in the Physics of Discrete Symmetries, Rome, Italy, 6-11 Dec 201
Electroweak and Flavour Structure of a Warped Extra Dimension with Custodial Protection
We present the electroweak and flavour structure of a model with a warped
extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x
U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the
Higgs system allowing to eliminate large contributions to the T parameter,
whereas the P_LR symmetry and the enlarged fermion representations provide a
custodial symmetry for flavour diagonal and flavour changing couplings of the
SM Z boson to left-handed down-type quarks. We diagonalise analytically the
mass matrices of charged and neutral gauge bosons including the first KK modes.
We present the mass matrices for quarks including heavy KK modes and discuss
the neutral and charged currents involving light and heavy fields. We give the
corresponding complete set of Feynman rules in the unitary gauge.Comment: 74 pages, 2 figures. clarifying comments and references added,
version to be published in JHE
Patterns of Flavour Violation in a Warped Extra Dimensional Model with Custodial Protection
We present a particular warped extra dimensional model, where the flavour
diagonal and flavour non-diagonal Z boson couplings to left-handed down quarks
are protected by the custodial symmetry P_LR. After a brief introduction of the
model and of its main theoretical motivations, we present a complete study of
rare K and B meson decays, including K+ --> pi+ nu anti-nu, K_L --> pi0 nu
anti-nu, B_{s,d} --> mu+ mu- and B_{s,d} --> X_{s,d} nu anti-nu. In particular
we restrict the parameter space of the model to the subspace which fits all
quark masses, CKM mixing parameters and all the measured Delta F=2 observables,
keeping the Kaluza-Klein scale in the reach of LHC (~(2-3)TeV). There we show
that, in addition to the one loop contribution of the Standard Model (SM), the
dominating new physics contribution to the rare decays of K and B_{s,d} mesons
is the tree level exchange of the Z boson of the SM governed by right-handed
couplings to down-type quarks. In order to reduce the parameter dependence, we
study correlations between various branching ratios of B and K mesons and
between Delta F=1 and Delta F=2 observables. The patterns that we find allow to
distinguish this new physics scenario from the SM and can offer an opportunity
to future experiments to confirm or rule out the model.Comment: 10 pages, 8 figures, To appear in the proceedings of DISCRETE '08,
11-16 December 2008, Valencia, Spai
On CP Asymmetries in Two-, Three- and Four-Body D Decays
Indirect and direct CP violations have been established in K_L and B_d
decays. They have been found in two-body decay channels -- with the exception
of K_L to pi^+ pi^- e^+ e^- transitions. Evidence for direct CP asymmetry has
just appeared in LHCb data on A_{CP}(D^0 to K^+ K^-) - A_{CP}(D^0 to pi^+ pi^-)
with 3.5 sigma significance. Manifestations of New Dynamics (ND) can appear in
CP asymmetries just below experimental bounds. We discuss D^{\pm}_{(s)},
D^0/\bar D^0 and D_L/D_S transitions to 2-, 3- and 4-body final states with a
comment on predictions for inclusive vs. exclusive CP asymmetries. In
particular we discuss T asymmetries in D to h_1 h_2 l^+ l^- in analogy with K_L
to pi^+ pi^- e^+ e^- transitions due to interference between M1, internal
bremsstrahlung and possible E1 amplitudes. Such an effect depends on the
strength of CP violation originating from the ND -- as discussed here for
Little Higgs Models with T parity and non-minimal Higgs sectors -- but also in
the interferences between these amplitudes even in the Standard Model (SM).
More general lessons can be learnt for T asymmetries in non-leptonic D decays
like D to h_1h_2 h_3 h_4. Such manifestations of ND can be tested at LHCb and
other Super-Flavour Factories like the projects at KEK near Tokyo and at Tor
Vergata/Frascati near Rome.Comment: 27 pages, 6 figures. Revised with current results from LHCb and HFAG
and further interpretation
Inferior frontal oscillations reveal visuo-motor matching for actions and speech: evidence from human intracranial recordings.
The neural correspondence between the systems responsible for the execution and recognition of actions has been suggested both in humans and non-human primates. Apart from being a key region of this visuo-motor observation-execution matching (OEM) system, the human inferior frontal gyrus (IFG) is also important for speech production. The functional overlap of visuo-motor OEM and speech, together with the phylogenetic history of the IFG as a motor area, has led to the idea that speech function has evolved from pre-existing motor systems and to the hypothesis that an OEM system may exist also for speech. However, visuo-motor OEM and speech OEM have never been compared directly. We used electrocorticography to analyze oscillations recorded from intracranial electrodes in human fronto-parieto-temporal cortex during visuo-motor (executing or visually observing an action) and speech OEM tasks (verbally describing an action using the first or third person pronoun). The results show that neural activity related to visuo-motor OEM is widespread in the frontal, parietal, and temporal regions. Speech OEM also elicited widespread responses partly overlapping with visuo-motor OEM sites (bilaterally), including frontal, parietal, and temporal regions. Interestingly a more focal region, the inferior frontal gyrus (bilaterally), showed both visuo-motor OEM and speech OEM properties independent of orolingual speech-unrelated movements. Building on the methodological advantages in human invasive electrocorticography, the present findings provide highly precise spatial and temporal information to support the existence of a modality-independent action representation system in the human brain that is shared between systems for performing, interpreting and describing actions
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