Short Distance Scale Research Articles

Final state interactions in Krightarrow pi pi decays: Delta I=1/2 rule vs. varepsilon '/varepsilon

Dispersive effects from strong pi pi rescattering in the final state interaction (FSI) of weak Krightarrow pi pi decays are revisited with the goal to have a global view on their relative importance for the Delta I=1/2 rule and the ratio varepsilon '/varepsilon in the standard model (SM). We point out that this goal cannot be reached within a pure effective (meson) field approach like chiral perturbation theory in which the dominant current–current operators governing the Delta I=1/2 rule and the dominant density–density (four-quark) operators governing varepsilon '/varepsilon cannot be disentangled from each other. But in the context of a dual QCD approach, which includes both long-distance dynamics and the UV completion, that is, QCD at short-distance scales, such a distinction is possible. We find then that beyond the strict large N limit, N being the number of colours, FSIs are likely to be important for the Delta I=1/2 rule but much less relevant for varepsilon '/varepsilon . The latter finding diminishes significantly hopes that improved calculations of varepsilon '/varepsilon would bring its SM prediction to agree with the experimental data, opening thereby an arena for important new physics contributions to this ratio.

MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE

ABSTRACT On 2015 June 16, Fermi-LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak >100 MeV flux of ∼3.6 × 10−5 photons cm−2 s−1, averaged over orbital period intervals. It is historically the highest γ-ray flux observed from the source, including past EGRET observations, with the γ-ray isotropic luminosity reaching ∼1049 erg s−1. During the outburst, the Fermi spacecraft, which has an orbital period of 95.4 minutes, was operated in a special pointing mode to optimize the exposure for 3C 279. For the first time, significant flux variability at sub-orbital timescales was found in blazar observations by Fermi-LAT. The source flux variability was resolved down to 2-minute binned timescales, with flux doubling times of less than 5 minutes. The observed minute-scale variability suggests a very compact emission region at hundreds of Schwarzschild radii from the central engine in conical jet models. A minimum bulk jet Lorentz factor (Γ) of 35 is necessary to avoid both internal γ-ray absorption and super-Eddington jet power. In the standard external radiation Comptonization scenario, Γ should be at least 50 to avoid overproducing the synchrotron self-Compton component. However, this predicts extremely low magnetization (∼5 × 10−4). Equipartition requires Γ as high as 120, unless the emitting region is a small fraction of the dissipation region. Alternatively, we consider γ rays originating as synchrotron radiation of γ e ∼ 1.6 × 106 electrons, in a magnetic field B ∼ 1.3 kG, accelerated by strong electric fields E ∼ B in the process of magnetoluminescence. At such short distance scales, one cannot immediately exclude the production of γ-rays in hadronic processes.

What do correlations tell us about anthropogenic–biogenic interactions and SOA formation in the Sacramento plume during CARES?

Abstract. During the Carbonaceous Aerosols and Radiative Effects Study (CARES) the US Department of Energy (DOE) G-1 aircraft was used to sample aerosol and gas phase compounds in the Sacramento, CA, plume and surrounding region. We present data from 66 plume transects obtained during 13 flights in which southwesterly winds transported the plume towards the foothills of the Sierra Nevada. Plume transport occurred partly over land with high isoprene emission rates. Our objective is to empirically determine whether organic aerosol (OA) can be attributed to anthropogenic or biogenic sources, and to determine whether there is a synergistic effect whereby OA concentrations are enhanced by the simultaneous presence of high concentrations of carbon monoxide (CO) and either isoprene, MVK + MACR (sum of methyl vinyl ketone and methacrolein), or methanol, which are taken as tracers of anthropogenic and biogenic emissions, respectively. Linear and bilinear correlations between OA, CO, and each of three biogenic tracers, “Bio”, for individual plume transects indicate that most of the variance in OA over short timescales and distance scales can be explained by CO. For each transect and species a plume perturbation, (i.e., ΔOA, defined as the difference between 90th and 10th percentiles) was defined and regressions done amongst Δ values in order to probe day-to-day and location-dependent variability. Species that predicted the largest fraction of the variance in ΔOA were ΔO3 and ΔCO. Background OA was highly correlated with background methanol and poorly correlated with other tracers. Because background OA was ∼ 60 % of peak OA in the urban plume, peak OA should be primarily biogenic and therefore non-fossil, even though the day-to-day and spatial variability of plume OA is best described by an anthropogenic tracer, CO. Transects were split into subsets according to the percentile rankings of ΔCO and ΔBio, similar to an approach used by Setyan et al. (2012) and Shilling et al. (2013) to determine if anthropogenic–biogenic (A–B) interactions enhance OA production. As found earlier, ΔOA in the data subset having high ΔCO and high ΔBio was several-fold greater than in other subsets. Part of this difference is consistent with a synergistic interaction between anthropogenic and biogenic precursors and part to an independent linear dependence of ΔOA on precursors. The highest values of ΔO3, along with high temperatures, clear skies, and poor ventilation, also occurred in the high ΔCO–high ΔBio data set. A complicated mix of A–B interactions can result. After taking into account linear effects as predicted from low concentration data, an A–B enhancement of OA by a factor of 1.2 to 1.5 is estimated.

Probing superfast quarks in nuclei through dijet production at the LHC

We investigate dijet production from proton-nucleus collisions at the Large Hadron Collider (LHC) as a means for observing superfast quarks in nuclei with Bjorken $x>1$. Kinematically, superfast quarks can be identified through directly measurable jet kinematics. Dynamically, their description requires understanding several elusive properties of nuclear QCD, such as nuclear forces at very short distances, as well as medium modification of parton distributions in nuclei. In the present work, we develop a model for nuclear parton distributions at large $x$ in which the nuclear dynamics at short distance scales are described by two- and three-nucleon short range correlations (SRCs). Nuclear modifications are accounted for using the color screening model, and an improved description of the EMC effect is reached by using a structure function parametrization that includes higher-twist contributions. We apply QCD evolution at the leading order to obtain nuclear parton distributions in the kinematic regime of the LHC, and based on the obtained distributions calculate the cross section for dijet production. We find not only that superfast quarks can be observed at the LHC, but also that they provide sensitivity to the practically unexplored three-nucleon SRCs in nuclei. Additionally, the LHC can extend our knowledge of the EMC effect to large $Q^2$ where higher-twist effects are negligible.

Flavour physics: Status and perspectives

The pattern of quark flavour violation predicted by the Standard Model agrees within theoretical and experimental uncertainties with the available data except for a number of intriguing anomalies that require further investigation. In the coming flavour precision era a multitude of new observables will be measured and the accuracy of the measurements of quark flavour violating rare processes and of the relevant lattice QCD calculations will be significantly improved. This will allow us not only to clarify these anomalies but also hopefully to discover new physics (NP). On the other hand a discovery of charged lepton flavour violation and of non‐vanishing electric dipole moments (EDMs) of particles would be a clear signal of NP. Most importantly the unique role of quark and lepton flavour physics and of EDMs in the coming years will be to allow us to get insight into the dynamics well beyond the reach of high energy processes at the LHC. In fact scales as short as 10−21 m (Zeptouniverse) corresponding to energy scale of 200 TeV or even shorter distance scales can be explored in this manner. We discuss the requirements that have to be met for such a flavour expedition to the Zeptouniverse to be successful. In particular we emphasize the power of correlations between flavour observables in the search for NP. In this context the proposed DNA charts allow for a clear distinction between various alternatives for the new dynamics at the LHC scales and at much shorter distance scales. image

Covariant non-commutative space–time

We introduce a covariant non-commutative deformation of 3+1-dimensional conformal field theory. The deformation introduces a short-distance scale ℓp, and thus breaks scale invariance, but preserves all space–time isometries. The non-commutative algebra is defined on space–times with non-zero constant curvature, i.e. dS4 or AdS4. The construction makes essential use of the representation of CFT tensor operators as polynomials in an auxiliary polarization tensor. The polarization tensor takes active part in the non-commutative algebra, which for dS4 takes the form of so(5,1), while for AdS4 it assembles into so(4,2). The structure of the non-commutative correlation functions hints that the deformed theory contains gravitational interactions and a Regge-like trajectory of higher spin excitations.

Can we reach the Zeptouniverse with rare K and B s,d decays?

The Large Hadron Collider (LHC) will directly probe distance scales as short as 10−19 m, corresponding to energy scales at the level of a few TeV. In order to reach even higher resolutions before the advent of future high-energy colliders, it is necessary to consider indirect probes of New Physics (NP), a prime example being ΔF = 2 neutral meson mixing processes, which are sensitive to much shorter distance scales. However ΔF = 2 processes alone cannot tell us much about the structure of NP beyond the LHC scales. To identify for instance the presence of new quark flavour-changing dynamics of a left-handed (LH) or right-handed (RH) nature, complementary results from ΔF = 1 rare decay processes are vital. We therefore address the important question of whether NP could be seen up to energy scales as high as 200 TeV, corresponding to distances as small as $$ \mathcal{O}\left(1{0}^{-21}\right)\mathrm{m} $$ — the Zeptouniverse — in rare K and B s,d decays, subject to present ΔF = 2 constraints and perturbativity. We focus in particular on a heavy Z ′ gauge boson. If restricted to purely LH or RH Z ′ couplings to quarks, we find that rare K decays, in particular $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ and $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ , allow us to probe the Zeptouniverse. On the other hand rare B s and B d decays, which receive stronger ΔF = 2 constraints, allow us to reach about 15 TeV. Allowing for both LH and RH couplings a loosening of the ΔF = 2 constraints is possible, and we find that the maximal values of M Z′ at which NP effects could be found that are consistent with perturbative couplings are approximately 2000 TeV for K decays and 160 TeV for rare B s,d decays. Because Z ′ exchanges in the B s,d → μ + μ − rare decays are helicity suppressed, we also consider tree-level scalar exchanges for these decays, for which we find that scales close to 1000 TeV can be probed for the analogous pure and combined LH and RH scenarios. We further present a simple idea for an indirect determination of M Z′ that could be realised at the next linear e + e − or μ + μ − collider and with future precise flavour data.

Phylogeography of Hepialus humuli (L.) (Lepidoptera: Hepialidae) in Europe: short distance vs. large scale postglacial expansions from multiple Alpine refugia and taxonomic implications

We explore the phylogeography of the common ghost moth, Hepialus humuli (Linnaeus) in Europe based on 1451 bp Cytochromeoxydase Subunit 1 (COI) mtDNA and 617 bp Ribosomal protein Subunit 5 (RpS5) ntDNA with special focus on populations in the Alps and surrounding regions, as well as northern Europe. While RpS5 fails to recover any phylogeographic signal, COI reveals a remarkable pattern with central European populations separated in four well-defined groups. The most divergent group is restricted to northern Italy and southern Austria and geographically isolated from the others; one group is found only in the central-northern region south of Lake Constance (Liechtenstein, western Austria) and co-occurs with the two other groups, from north-eastern Alps and north-western Alps respectively. We conclude that the southern and central groups are relicts from a previous Pleistocene glacial maximum, whereas the two latter groups were isolated during the last glacial maximum in a western and an eastern refugium respectively, the exact extends of these refugia are uncertain. The central group has subsequently interbred with the two other northern groups and probably only exists today as ancient mtDNA haplotypes. The north-western and north-eastern groups have spread considerably and overlap over a large part of their range in the Alps and surrounding areas. Following the last glacial maximum, the north-western group spread into western Europe as far as Normandy, but the English Channel has apparently acted as a dispersal barrier. The north-eastern group spread into eastern and northern Europe, including Scandinavia, and possibly into the Balkans as well. The British Isles as well as the North Atlantic islands groups, the Faroese and Shetlands were colonised from southern Scandinavia or northern Germany, likely via Doggerland. Despite the deep divergence in mtDNA between the populations in Italy and southern Austria, and the remaining populations, there are no consistent morphological differences, and we conclude that there is no evidence that the southern populations should be considered a separate species. Although the populations in the Shetland and Faroese islands are phenotypically distinct from most other populations, we find no genetic or genitalia morphological differences between these populations and the rest. We therefore conclude that they display what can be termed cryptic genetic homogeneity. As the phenotypic variation is not unique to these populations either, we synonymise the North Atlantic subspecies H. humuli thulensis Newman syn.n. with H. humuli humuli.

The reproductive ecology of Ulmus laevis Pallas in a transformed habitat

From a life-cycle perspective seed dispersal is a key factor for population dynamics. However, little is known on seed dispersal mechanisms in riparian hydrochorous and anemochorous canopy tree species. We studied Ulmus laevis Pallas reproductive biology in a human transformed population with lack of recruitment, during three consecutive years, in order to evaluate the species’ recovery capabilities. We investigated fruit release timing and rates, and how these are affected by meteorological variables with generalized linear models. Seed production, dispersal distances, dispersal patterns and predation rates were evaluated with inverse modeling. Results show that the stand did not suffer from source limitation, in the fecundity sense. Despite samaras being winged nuts, wind did not disperse these long distances, as 95% of full samaras land at less than 30m from the mother tree. We did not observe secondary dispersal in this stand. Therefore, we hypothesize that for this species water may be responsible for long distance dispersal, and wind would be effective in short distance dispersal. This coupled system would increase efficiency in seed arrival at appropriate habitats for colonization, at both short and long distance scale. Empty samara production and the proportion of these in relation to full samaras are important for diminishing pre- and post-dispersal predation rates. Our results also shed light on how human-induced changes in water-table and river regulation may affect seed dispersal and recruitment in riparian forests. Finally, U. laevis short-term conservation measures are discussed, while long term conservation requires natural hydrological regimes restoration so as to facilitate seed transport and deposition in adequate microsites.

THREE-DIMENSIONAL MAPS OF THE MAGELLANIC CLOUDS USING RR LYRAE STARS AND CEPHEIDS. I. THE LARGE MAGELLANIC CLOUD

The new data for Cepheids and RR Lyrae stars of the Optical Gravitational Lensing Experiment (OGLE-III) survey allow us to study the three-dimensional distribution of stars corresponding to young (a few tens to a few hundreds of millions of years) and old (typically older than ~9 Gyr) populations of the Large Magellanic Cloud (LMC) traced by these variable stars. We estimate the distance to 16949 RR Lyrae stars by using their photometrically estimated metallicities. Furthermore the periods of 1849 Cepheids are used to determine their distances. Three-dimensional maps are obtained by using individual reddening estimates derived from the intrinsic color of these stars. The resulting median distances of the RR Lyrae stars and Cepheids appear to resolve the long and short distance scale problem for our sample. With median distances of 53.1 \pm 3.2 kpc for the RR Lyrae stars and 53.9 \pm 1.8 kpc for the Cepheids, these two distance indicators are in very good agreement with each other in contrast to a number of earlier studies. Individual reddening estimates allow us to resolve the distance discrepancies often observed while comparing Cepheids and RR Lyrae stars. For both stellar populations we find the inclination angle of the LMC to be 32{\deg} \pm 4{\deg} and the mean position angle to be 115{\deg} \pm 15{\deg}. The position angle increases with galactocentric radius, indicative of mild twisting. Within the innermost 7 degrees of the LMC covered by OGLE III the change in position angle amounts to more than 10 degrees. The depth of the Cepheids is found to be 1.7 \pm 0.2 kpc. The bar stands out as an overdensity both in RR Lyrae stars and in Cepheids. In RR Lyrae stars the bar can be traced as a protruding overdensity with a line-of-sight depth of almost 5 kpc in front of the main body of the disk.

Open flavour charmed mesons in a quantum chromodynamics potential model

We modify the mesonic wave function by using a short distance scale r0 in analogy with hydrogen atom and estimate the values of masses and decay constants of the open flavour charm mesons D, Ds and Bc within the framework of a QCD potential model. We also calculate leptonic decay widths of these mesons to study branching ratios and lifetime. The results are in good agreement with experimental and other theoretical values.

Entropy bound with generalized uncertainty principle in general dimensions

In this letter, the entropy bound for local quantum field theories (LQFT) is studied in a class of models of the generalized uncertainty principle (GUP) which predicts a minimal length as a reflection of the quantum gravity effects. Both bosonic and fermionic fields confined in an arbitrary spatial dimension d ⩾ 4 ball are investigated. It is found that the GUP leads to the same scaling A(d−3)/(d−2)d−2 correction to the entropy bound for bosons and fermions, although the coefficients of this correction are different for each case. Based on our calculation, we conclude that the GUP effects can become manifest at the short distance scale. Some further implications and speculations of our results are also discussed.

Spatial and temporal variability of aerosol particles in Arctic spring

AbstractThe objective of this work is to investigate the variability in the aerosol particle number concentration in Arctic spring. The Indirect and Semi‐Direct Aerosol Campaign (ISDAC) was conducted during April 2008 in the vicinities of Fairbanks and Barrow, Alaska. Aircraft‐based measurements of total aerosol particle number concentration (Na) in the size range of 0.12–3 µm diameter were obtained using a passive cavity aerosol spectrometer probe (PCASP‐100X). The analysis considers Na during cloud‐free periods in biomass burning (BB) and non‐BB aerosol loading scenarios, the latter including background cases and cases with elevated concentration in layers. The BB cases had air masses originating mainly from Russian and Asian forest and crop fires, whereas the non‐BB cases originated predominantly from Arctic or oceanic regions. The average Na for all non‐BB cases was 127 cm−3, while that for all BB cases was Na = 720 cm−3. These estimates do not, however, capture the details of aerosol particle layers encountered during most flights. Variability in Na was considered for constant altitude (horizontal) flight legs ranging from 50 to 650 km in length, as well as for vertical flight profiles up to 7 km above sea level. When aerosol particle layers were encountered, Na rapidly increased from 20 to 550 cm−3, and reached up to 2200 cm−3 within air masses dominated by BB plumes. The observed variability in Na may have important implications for estimating cloud microphysical properties as well as estimates of particle properties used in global climate model simulations, because averaging over large space‐ or time‐scales may not represent real atmospheric conditions. The analysis demonstrates the difficulty in interpreting average aerosol particle characteristics along longer flight legs, particularly during cases with higher particle loading that varies over shorter distance scales and time periods. Copyright © 2012 Royal Meteorological Society and Crown in the right of Canada.

Detecting Intramolecular Conformational Dynamics of Single Molecules in Short Distance Range with Subnanometer Sensitivity

Single molecule detection is useful for characterizing nanoscale objects such as biological macromolecules, nanoparticles and nanodevices with nanometer spatial resolution. Fluorescence resonance energy transfer (FRET) is widely used as a single-molecule assay to monitor intramolecular dynamics in the distance range of 3-8 nm. Here we demonstrate that self-quenching of two rhodamine derivatives can be used to detect small conformational dynamics corresponding to subnanometer distance changes in a FRET-insensitive short-range at the single molecule level. A ParM protein mutant labeled with two rhodamines works as a single molecule adenosine 5'-diphosphate (ADP) sensor that has 20 times brighter fluorescence signal in the ADP bound state than the unbound state. Single molecule time trajectories show discrete transitions between fluorescence on and off states that can be directly ascribed to ADP binding and dissociation events. The conformational changes observed with 20:1 contrast are only 0.5 nm in magnitude and are between crystallographic distances of 1.6 and 2.1 nm, demonstrating exquisite sensitivity to short distance scale changes. The systems also allowed us to gain information on the photophysics of self-quenching induced by rhodamine stacking: (1) photobleaching of either of the two rhodamines eliminates quenching of the other rhodamine fluorophore and (2) photobleaching from the highly quenched, stacked state is only 2-fold slower than from the unstacked state.

The Oscillation Frequency of B and B̄ Mesons in a QCD Potential Model with Relativistic Effects

Wavefunction at the origin, with the incorporation of a relativistic effect, leads to singularity in a specific potential model. To regularize the wavefunction, we introduced a short distance scale and used it to estimate the mass and decay constants of Bd and Bs mesons within the QCD potential model. These values were then used to compute the oscillation frequency, ΔmB, of Bd and Bs mesons. The values were found to be in good agreement with experimental and other theoretical values.

Potential for Establishing Nonvertical Flow within the Vadose Zone

Laboratory experiments and numerical studies are used to study the potential to induce water flux in the vadose zone, which is characterized by significant horizontal components of the water velocity. Specifically, a question is addressed as to whether water can be injected or withdrawn from lenses or layers of fine sediments (bordered by coarse sediments), thus establishing flow in those portions of the vadose zone commonly associated with higher moisture contents and a higher mass of dissolved contaminants. Laboratory experiments provided the base‐line proof of concept of the ability to induce horizontal components to flow in unsaturated sediments through use of suction‐cup lysimeters, but were limited to ideal media and short distance scales (<0.5 m). A numerical model was used in combination with published moisture retention and relative permeability parameters for a variety of sediment types to study conditions under which such horizontal flow components might be induced over substantially greater distances (e.g., 10 m). While these numerical results support arguments that flow induction is theoretically possible, induced flow will generally result in slow transport velocities such that application will likely be limited either to short flow distances (e.g., less than a meter) or long‐term (>50 years) time scales, and only with thorough knowledge of subsurface heterogeneity. Implications of this work beyond the present study may include continuing discussions of constructed capillary barriers and development of improved technologies for removal of water from the vadose zone.

BPS solitons in Lifshitz field theories

Lorentz-invariant scalar field theories in d+1 dimensions with second-order derivative terms are unable to support static soliton solutions that are both finite in energy and stable for d>2, a result known as Derrick's theorem. Lifshitz theories, which introduce higher-order spatial derivatives, need not obey Derrick's theorem. We construct stable, finite-energy, static soliton solutions in Lifshitz scalar field theories in 3+1 dimensions with dynamical critical exponent z=2. We exhibit three generic types: non-topological point defects, topological point defects, and topological strings. We focus mainly on Lifshitz theories that are defined through a superpotential and admit BPS solutions. These kinds of theories are the bosonic sectors of supersymmetric theories derived from the stochastic dynamics of a scalar field theory in one higher dimension. If nature obeys a Lifshitz field theory in the ultraviolet, then the novel topological defects discussed here may exist as relics from the early universe. Their discovery would prove that standard field theory breaks down at short distance scales.

Influence of cell cycle phase on apparent diffusion coefficient in synchronized cells detected using temporal diffusion spectroscopy

The relationship between the apparent diffusion coefficient of tissue water measured by MR methods and the physiological status of cells is of particular relevance for better understanding and interpretation of diffusion-weighted MRI. In addition, there is considerable interest in developing diffusion-dependent imaging methods capable of providing novel information on tissue microstructure, including intracellular changes. To this end, both the conventional pulsed gradient spin-echo methods and the oscillating gradient spin-echo method, which probes diffusion over very short distance (<<cell size) and time scales, were used to measure apparent diffusion coefficient of synchronized packed HL-60 cells at 7 T. The results show that the pulsed gradient spin-echo method with relatively long diffusion times does not detect changes in apparent diffusion coefficient when structural variations arise during cell division. On the contrary, the oscillating gradient spin-echo method can detect and quantify major changes in intracellular organization that occur during mitosis by appropriate choice of gradient frequency. Cell structural parameters, including cell size, intracellular diffusion coefficient, and surface-to-volume ratio were also obtained by fitting the oscillating gradient spin-echo data to simple analytical models. These oscillating gradient spin-echo features may be used in diffusion-weighted MRI to create parametric maps that may be useful for detecting cancer or changes caused by treatment.

NEUTRINO MASS AND GRAND UNIFICATION OF FLAVOR

The problem of understanding quark mass and mixing hierarchies has been an outstanding problem of particle physics for a long time. The discovery of neutrino masses in the past decade, exhibiting mixing and mass patterns so very different from the quark sector has added an extra dimension to this puzzle. This is specially difficult to understand within the framework of conventional grand unified theories which are supposed to unify the quarks and leptons at short distance scales. In the paper, I discuss a recent proposal by Dutta, Mimura and this author that appears to provide a promising way to resolve this puzzle. After stating the ansatz, we show how it can be realized within a SO(10) grand unification framework. Just as Gell-Mann's suggestion of SU(3) symmetry as a way to understand the hadronic flavor puzzle of the sixties led to the foundation of modern particle physics, one could hope that a satisfactory resolution of the current quark-lepton flavor problem would provide fundamental insight into the nature of physics beyond the standard model.

Narrow resonances and short-range interactions

Narrow resonances in systems with short-range interactions are discussed in an effective field theory (EFT) framework. An effective Lagrangian is formulated in the form of a combined expansion in powers of a momentum $Q\ensuremath{\ll}\ensuremath{\Lambda}$---a short-distance scale---and an energy difference $\ensuremath{\delta}\ensuremath{\epsilon}=|E\ensuremath{-}{\ensuremath{\epsilon}}_{0}|\ensuremath{\ll}{\ensuremath{\epsilon}}_{0}$---a resonance peak energy. At leading order in the combined expansion, a two-body scattering amplitude is the sum of a smooth background term of order ${Q}^{0}$ and a Breit-Wigner term of order ${Q}^{2}(\ensuremath{\delta}\ensuremath{\epsilon}){}^{\ensuremath{-}1}$ which becomes dominant for $\ensuremath{\delta}\ensuremath{\epsilon}\ensuremath{\lesssim}{Q}^{3}$. Such an EFT is applicable to systems in which short-distance dynamics generates a low-lying quasistationary state. The EFT is generalized to describe a narrow low-lying resonance in a system of charged particles. It is shown that in the case of Coulomb repulsion, a two-body scattering amplitude at leading order in a combined expansion is the sum of a Coulomb-modified background term and a Breit-Wigner amplitude with parameters renormalized by Coulomb interactions.