8098307
Can nearby resonances enhance D0 - anti-D0 mixing?
We consider the possibility that D^0 - anti-D^0 mixing undergoes resonant enhancement. Various scenarios are explored, including the potential effects of nearby pseudoscalar or scalar quark-antiquark (Q - anti-Q) resonances as well as of hybrid quark-antiquark-gluon Q - anti-Q G states. Assuming reasonable values for the resonance parameters we find relatively sizeable contributions from individual resonances to both \Delta m_D and \Delta \Gamma_D. We derive a variant of the GIM cancellation mechanism for the resonance amplitudes and show that broken SU(3) can allow for sizeable residual effects. Additional input from meson spectroscopy and lattice gauge simulations will be needed to improve the accuracy of these predictions.
35942201
Is B-->Xs gamma equal to b-->s gamma ? Spectator contributions to rare inclusive B decays.
In $B \to X_s \gamma $ there are perturbative $QCD$ corrections at order $\alpha_s$ not only to the single quark line process $ b \to s \gamma$ but also coming from a set of diagrams where the weak interaction vertex involves a gluon which interacts with the spectator quark in the B hadron. We discuss the impact of the full set of these diagrams. These can influence the decay rate and also the line shape of the photon spectrum as they favor a softer photon energy than does the pure spectator decay $b \to s \gamma$. A subset of these diagrams generate differences in the decay rates for charged and neutral B's , $B^+ \to X_s \gamma$ vs. $B^0 \to X_s \gamma$ which can be searched for experimentally, although our calculation indicates that the effect will be hard to observe. Bound state effects turn out to be required to give rise to spectator corrections to the decay rate at order $\alpha_s$. The resulting contribution to the total rate is rather small (of about $5 \% $ ), although the effect is somewhat larger on portions of the photon spectrum.
14759150
Heavy meson molecules in effective field theory
We consider the implications from the possibility that the recently observed state X(3872) is a meson-antimeson molecule. We write an effective Lagrangian consistent with the heavy-quark and chiral symmetries needed to describe X(3872). We explore the consequences of the assumption that X(3872) is a molecular bound state of D�0 and D0 mesons for the existence of bound states in the D0D0 and D�0D �0
117901603
X(3872) in effective field theory
We consider the implications from the possibility that the recently observed state X(3872) is a meson‐antimeson molecule. We write an effective Lagrangian consistent with the heavy‐quark and chiral symmetries needed to describe X(3872) and study its properties.
118687281
Hadronic D and D(s) Meson Decays
We provide a comprehensive review of hadronic decays of D and D_s mesons. We discuss current theoretical and experimental challenges and successes in understanding of hadronic transitions of those mesons. A brief overview of the theoretical and experimental tools are given before discussing the absolute branching fractions for D and D_s mesons. Cabibbo suppressed and rare hadronic decays are discussed and compared with theory before discussing our understanding of hadronic multibody decays.
17946700
CP-violation in charm
I review recent results in theoretical and experimental analyses of CP-violation in charmed transitions, paying particular attention to constraints on parameters of beyond the Standard Model interactions.
119230860
On the aether-like Lorentz-breaking actions
We demonstrate the generation of the CPT-even, aether-like Lorentz-breaking actions for the scalar and electromagnetic fields via their appropriate Lorentz-breaking coupling to spinor fields in three, four and five space-time dimensions. Besides, we show that the aether-like terms for the spinor field also can be generated as a consequence of the same couplings. Also we discuss the dispersion relations in the theories with aether-like Lorentz-breaking terms and find the tree-level effective (Breit) potential for fermion scattering and the one-loop effective potential corresponding to the action of the scalar field.
119224824
On the effective potential for Horava-Lifshitz-like theories
The Horava-Lifshitz (HL) approach [1] has recently acquired a great scientific attention. This approach is characterized by an essential asymmetry between space and time coordinates (space-time anisotropy): the equations of motion of the theory are invariant under the rescaling x → bx, t → bt, where z, the critical exponent, is a number characterizing its ultraviolet behaviour. The main reason for it is that for the HL-like reformulation of the known field theory models with a nontrivial critical exponent z > 1 leads to an improvement of the renormalization of these models. In particular, the four-dimensional gravity becomes renormalizable at z = 3. Different issues related to the HL gravity, including its cosmological aspects [2], exact solutions [3], black holes [4] were considered in a number of papers. At the same time, the study of the impacts of the HL extension to other field theories is a very interesting problem. Some aspects of the HL generalizations for the gauge field theories were presented in [5]. Renormalizability of the scalar field theory models with space-time anisotropy has been discussed in details in [6]. The four-fermion HL-like theory has been studied in [7]. The Casimir effect for the HL-like scalar field theory has been considered in [8]. In [9], the HL modifications of the CP were studied. The possibility of restoration of the Lorentz symmetry in the theories with the space-time anisotropy is discussed in [5, 10]. It is well known that the effective potential is a key object in the quantum field theory useful for studying many of its aspects. Some interesting results for the HL-like theories have been obtained in the papers [11, 12] where the effective potential for the φ and the Liouville-
18464471
Aharonov-Bohm effect on noncommutative plane: A Coherent state approach
Abstract We formulate in a systematic manner the coherent state approach and apply it to study Aharonov–Bohm effect in the field theory context. Within this approach, we verify that the scattering amplitude is ultraviolet finite. Also, we prove that introduction of a quartic self-interaction for the scalar field allows to obtain a smooth commutative limit.
125450100
A Coherent State Formulation for the Relativistic Field Theories
118831899
Effective potential, Horava-Lifshitz-like theories, and finite temperature
We calculate the one-loop effective potential at finite temperature for the Horava-Lifshitz-like QED and Yukawa-like theories for arbitrary values of the critical exponent and the space-time dimension. Additional remarks on the zero temperature situation are also presented.