Search results for "MBD"
showing 10 items of 646 documents
Global Monopole in Palatini f(R) gravity
2018
We consider the space-time metric generated by a global monopole in an extension of General Relativity (GR) of the form $f(\mathcal{R})=\mathcal{R}-\lambda \mathcal{R}^2$. The theory is formulated in the metric-affine (or Palatini) formalism and exact analytical solutions are obtained. For $\lambda0$, instead, the metric is more closely related to the Reissner-Nordstr\"{o}m metric with a monopole charge and, in addition, it possesses a wormhole-like structure that allows for the geodesic completeness of the space-time. Our solution recovers the expected limits when $\lambda=0$ and also at the asymptotic far limit. The angular deflection of light in this spacetime in the weak field regime is…
New results on mesonic weak decay of p-shell Lambda-hypernuclei
2009
The FINUDA experiment performed a systematic study of the charged mesonic weak decay channel of $p$-shell $\Lambda$-hypernuclei. Negatively charged pion spectra from mesonic decay were measured with magnetic analysis for the first time for ${^{7}_{\Lambda}Li}$, ${^{9}_{\Lambda}Be}$, ${^{11}_{\Lambda}B}$ and ${^{15}_{\Lambda}N}$. The shape of the $\pi^{-}$ spectra was interpreted through a comparison with pion distorted wave calculations that take into account the structure of both hypernucleus and daughter nucleus. Branching ratios $\Gamma_{\pi^{-}}/\Gamma_{tot}$ were derived from the measured spectra and converted to $\pi^{-}$ decay rates $\Gamma_{\pi^{-}}$ by means of known or extrapolate…
Selected topics on Hadrons in Nuclei
2011
In this talk we report on selected topics on hadrons in nuclei. The first topic is the renormalization of the width of the $\Lambda(1520)$ in a nuclear medium. This is followed by a short update of the situation of the $\omega$ in the medium. The investigation of the properties of $\bar{K}$ in the nuclear medium from the study of the $(K_{flight},p)$ reaction is also addressed, as well as properties of X,Y,Z charmed and hidden charm resonances in a nuclear medium. Finally we address the novel issue of multimeson states.
Spiral Inflation with Coleman-Weinberg Potential
2015
We apply the idea of spiral inflation to Coleman-Weinberg potential, and show that inflation matching well observations is allowed for a symmetry-breaking scale ranging from an intermediate scale to GUT scale even if the quartic coupling $\lambda$ is of $\mathcal{O}(0.1)$. The tensor-to-scalar ratio can be of $\mathcal{O}(0.01)$ in case of GUT scale symmetry-breaking.
On quantum effects near the liquid-vapor transition in helium
2001
The liquid-vapor transition in He-3 and He-4 is investigated by means of path-integral molecular dynamics and the quantum virial expansion. Both methods are applied to the critical isobar and the critical isochore. While previous path-integral simulations have mainly considered the lambda transition and superfluid regime in He-4, we focus on the vicinity of the critical point and obtain good agreement with experimental results for the molar volume and the internal energy down to subcritical temperatures. We find that an effective classical potential that properly describes the two-particle radial distribution function exhibits a strong temperature dependence near the critical temperature. T…
Non-perturbative chiral approach to S-wave interactions
1998
The s-wave meson-nucleon interaction in the $S = -1$ sector is studied by means of coupled-channel Lippmann Schwinger equations, using the lowest order chiral Lagrangian and a cut off to regularize the loop integrals. The method reproduces succesfully the $\Lambda (1405)$ resonance and the $K^- p \to K^- p, \bar{K}^0 n, \pi^0 \Lambda, \pi^0 \Sigma, \pi^+ \Sigma^-, \pi^- \Sigma^+$ cross sections at low energies. The inclusion of the $\eta \Lambda, \eta \Sigma^0$ channels in the coupled system is found very important and allows a solution in terms of only the lowest order Lagrangian.
Model-Independent Evidence forJ/ψpContributions toΛb0→J/ψpK−Decays
2016
The data sample of Lambda(0)(b) -> J/psi pK(-) decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb(-1), is inspected for the presence of J/psi p or J/psi K- contributions with minimal assumptions about K(-)p contributions. It is demonstrated at more than nine standard deviations that Lambda(0)(b) -> J/psi pK(-) decays cannot be described with K- p contributions alone, and that J/psi K- contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P-c(+)-> J/psi p charmonium-pentaquark states in the same data sample.
Two-electron systems in strong laser fields
2009
In this paper we investigate the single and double ionization signals of ${\text{H}}_{2}$ molecules, with fixed and moving nuclei, as a function of laser intensity, for two different values of laser wavelength ($\ensuremath{\lambda}=390\text{ }\text{nm}$ and $\ensuremath{\lambda}=780\text{ }\text{nm}$), using an approach for evaluating the ionization signals which allows the investigation of relatively long-lasting pulses. The He system is first investigated to benchmark our calculation against already known results. We confirm the evidence of nonsequentiality in the ionization processes of all the systems investigated. Furthermore, we show that the nuclei motion enhances the double ionizat…
Multichannel0→2and1→2transition amplitudes for arbitrary spin particles in a finite volume
2015
We present a model-independent, nonperturbative relation between finite-volume matrix elements and infinite-volume $\mathbf{0}\ensuremath{\rightarrow}\mathbf{2}$ and $\mathbf{1}\ensuremath{\rightarrow}\mathbf{2}$ transition amplitudes. Our result accommodates theories in which the final two-particle state is coupled to any number of other two-body channels, with all angular momentum states included. The derivation uses generic, fully relativistic field theory and is exact up to exponentially suppressed corrections in the lightest particle mass times the box size. This work distinguishes itself from previous studies by accommodating particles with any intrinsic spin. To illustrate the utilit…
Measurements ofψ(3686)→K−ΛΞ¯++c.c.andψ(3686)→γK−ΛΞ¯++c.c.
2015
Using a sample of 1.06 x 10(8) psi(3686) events produced in e(+)e(-) collisions at root s = 3.686 GeV and collected with the BESIII detector at the BEPCII collider, we present studies of the decays psi(3686) -> K-Lambda(Xi) over bar (+) + c.c. and psi(3686) -> gamma K-Lambda(Xi) over bar (+) + c.c. We observe two hyperons, Xi(1690)(-) and Xi(1820)(-), in the K-Lambda invariant mass distribution in the decay psi(3686) -> K-Lambda(Xi) over bar (+) + c.c. with significances of 4.9 sigma and 6.2 sigma, respectively. The branching fractions of psi(3686) -> K-Lambda(Xi) over bar (+) + c.c., psi(3686) -> K-Sigma(0)(Xi) over bar (+) + c.c, psi(3686) -> gamma chi cJ -> gamma K-Lambda(Xi) over bar (+…