3D printing of optical materials: an investigation of the microscopic properties

3D printing technologies are currently enabling the fabrication of objects with complex architectures and tailored properties. In such framework, the production of 3D optical structures, which are typically based on optical transparent matrices, optionally doped with active molecular compounds and nanoparticles, is still limited by the poor uniformity of the printed structures. Both bulk inhomogeneities and surface roughness of the printed structures can negatively affect the propagation of light in 3D printed optical components. Here we investigate photopolymerization-based printing processes by laser confocal microscopy. The experimental method we developed allows the printing process to be investigated in-situ, with microscale spatial resolution, and in real-time. The modelling of the photo-polymerization kinetics allows the different polymerization regimes to be investigated and the influence of process variables to be rationalized. In addition, the origin of the factors limiting light propagation in printed materials are rationalized, with the aim of envisaging effective experimental strategies to improve optical properties of printed materials.Comment: 8 pages, 3 figure

Realization of Haldane's Exclusion Statistics in a Model of Electron-Phonon Interactions

We discuss an integrable model describing one-dimensional electrons interacting with two-dimensional anharmonic phonons. In the low temperature limit it is possible to decouple phonons and consider one-dimensional excitations separately. They have a trivial two-body scattering matrix and obey fractional statistics. As far as we know the original model presents the first example of a model with local bare interactions generating purely statistical interactions between renormalized particles. As a by-product we obtain non-trivial thermodynamic equations for the interacting system of two-dimensional phonons.Comment: 4 page

Evidence for CP Violation in B0 -> D+D- Decays

We report measurements of the branching fraction and CP violation parameters in B0 -> D+D- decays. The results are based on a data sample that contains 535 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20 (stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09, A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma confidence level. While the value of S is consistent with expectations from other measurements, the value of the parameter A favors large direct CP violation at the 3.2 sigma confidence level, in contradiction to Standard Model expectations.Comment: 12 pages, 3 figures, submitted to PR

Measurement of the near-threshold e+e−→DDˉe^+e^- \to D \bar D cross section using initial-state radiation

We report measurements of the exclusive cross section for $e^+e^- \to D \bar D$, where $D=D^0$ or $D^+$, in the center-of-mass energy range from the $D \bar D$ threshold to $5\mathrm{GeV}/c^2$ with initial-state radiation. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 $\mathrm{fb}^{-1}$.Comment: Presented at EPS07 and LP07 conferences, published in PRD(RC

Search for the X(1812) in B±→K±ωϕB^{\pm} \to K^{\pm} \omega \phi

We report on a search for the X(1812) state in the decay $B^{\pm} \to K^{\pm} \omega \phi$ with a data sample of $657\times10^6$ $B\bar{B}$ pairs collected with the Belle detector at the KEKB $e^+e^-$ collider. No significant signal is observed. An upper limit ${\cal B}(B^{\pm} \to K^{\pm} X(1812),X(1812) \to \omega \phi)<3.2\times 10^{-7}$ (90% C.L.) is determined. We also constrain the three-body decay branching fraction to be ${\cal B}(B^{\pm} \to K^{\pm} \omega \phi)$ $<$ 1.9 $\times 10^{-6}$ (90% C.L.).Comment: 5pages,2 figures(3 figure files). submitted to PRD(RC

Search for CP Violation in the Decays D0→KS0P0D^0\rightarrow K^0_S P^0

We have searched for CP violation in the decays $D^0\rightarrow K^0_S P^0$ where $P^0$ denotes a neutral pseudo-scalar meson which is either a $\pi^0$, $\eta$, or $\eta'$ using KEKB asymmetric-energy $e^+e^-$ collision data corresponding to an integrated luminosity of 791 fb$^{-1}$ collected with the Belle detector. No evidence of significant CP violation is observed. We report the most precise CP asymmetry measurement in the decay $D^0\rightarrow K^0_S\pi^0$ to date: $A_{CP}^{D^0\rightarrow K^0_S\pi^0}=(-0.28\pm0.19\pm0.10)$. We also report the first measurements of CP asymmetries in the decays $D^0\rightarrow K^0_S\eta$ and $D^0\rightarrow K^0_S\eta'$: $A_{CP}^{D^0\rightarrow K^0_S\eta}=(+0.54\pm0.51\pm0.16)$ and $A_{CP}^{D^0\rightarrow K^0_S\eta'}=(+0.98\pm0.67\pm0.14)$, respectively

Measurements of CP Violation in B0→D∗−π+B^0 \to D^{*-}\pi^+ and B0→D−π+B^0 \to D^- \pi^+ Decays

We report measurements of time dependent decay rates for $B^0 \to D^{(*)-}\pi^+$ decays and extraction of CP violation parameters that depend on $\phi_3$. Using fully reconstructed $D^{(*)}\pi$ events and partially reconstructed $D^{*}\pi$ events from a data sample that contains 386 million $B\bar{B}$ pairs that was collected near the $\Upsilon(4S)$ resonance, with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider, we obtain the CP violation parameters $S^+ (D^{(*)}\pi)$ and $S^- (D^{(*)}\pi)$. We obtain $S^+ (D^* \pi) = 0.049 \pm 0.020(\mathrm{stat}) \pm 0.011(\mathrm{sys})$, $S^- (D^* \pi) = 0.031 \pm 0.019(\mathrm{stat}) \pm 0.011(\mathrm{sys})$, and $S^+ (D \pi) = 0.031 \pm 0.030(\mathrm{stat}) \pm 0.012(\mathrm{sys})$, $S^- (D \pi) = 0.068 \pm 0.029(\mathrm{stat}) \pm 0.012(\mathrm{sys})$. These results are an indication of CP violation in $B^0 \to D^{*-}\pi^+$ and $B^0 \to D^- \pi^+$ decays at the $2.5 \sigma$ and $2.2 \sigma$ levels, respectively. If we use the values of $R_{D^{(*)}\pi}$ that are derived using assumptions of factorization and SU(3) symmetry, the branching fraction measurements for the $D_s^{(*)} \pi$ modes, and lattice QCD calculations, we can restrict the allowed region of $|\sin (2\phi_1 + \phi_3)|$ to be above 0.44 and 0.52 at 68% confidence level from the $D^* \pi$ and $D \pi$ modes, respectively.Comment: 14 pages, 12 figures, submitted to Physical Review

Bounds on the width, mass difference and other properties of X(3872) --> pi+pi-J/psi decays

We present results from a study of X(3872) --> pi+pi- J/psi decays produced via exclusive B--> K X(3872) decays. We determine the mass to be M_X(3872)= (3871.84\pm 0.27 (stat)\pm 0.19 (syst)) MeV, a 90% CL upper limit on the natural width of Gamma_X(3872) K+X(3872))xBf(X(3872)-->pi+pi-J/psi)=(8.61 \pm 0.82(stat) \pm 0.52 (syst)) x10^{-6}, and a ratio of branching fractions Bf(B0--> K0 X(3872))/BF(B+--> K+ X(3872))=0.50\pm 0.14(stat)\pm0.04(syst). The difference in mass between the X(3872)-->pi+pi-J/psi signals in B+ and B0 decays is Delta M_{X(3872)= (-0.69 \pm 0.97 (stat)} \pm 0.19 (syst)) MeV. A search for a charged partner of the X(3872) in the decays Bbar0-->K- X+ or B+-->K0X+, X+-->pi+pi0 J/psi resulted in upper limits on the product branching fractions for these processes that are well below expectations for the case that the X(3872) is the neutral member of an isospin triplet. In addition, we examine possible J^{PC} quantum number assignments for the X(3872) based on comparisons of angular correlations between final state particles in X(3872)-->pi+pi-J/psi decays with simulated data for J^{PC} values of 1^{++} and 2^{-+}. We examine the influence of rho-omega interference in the M(pi+pi-) spectrum. The analysis is based on a 711fb^{-1} data sample that contains 772 million BBbar meson pairs collected at the Upsilon(4S) resonance in the Belle detector at the KEKB e+e- collider.Comment: 15 pages, 10 figures and 6 tables. Submitted to Physical Review

Time-Dependent CP Asymmetries in B0 -> Ks pi0 gamma transitions

We report measurements of CP violation parameters in B0->Ks pi0 gamma transitions based on a data sample of 535x10^6 BB pairs collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. One neutral B meson is fully reconstructed in the B0->Ks pi0 gamma mode. The flavor of the accompanying B meson is identified from its decay products. For a Ks pi0 invariant mass up to 1.8 GeV/c^2, we obtain S = -0.10 +- 0.31 +- 0.07 and A = -0.20 +- 0.20 +- 0.06. For a Ks pi0 invariant mass near the K*0(892) resonance, we obtain S = -0.32 +0.36-0.33 +-0.05 and A=-0.20 +-0.24 +-0.05.Comment: 6 pages, 3 figures, accepted by PR

Measurement of Inclusive Radiative B-meson Decays with a Photon Energy Threshold of 1.7 GeV

Using 605/fb of data collected at the Upsilon(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B to X_s gamma. For the lower photon energy thresholds of 1.7, 1.8, 1.9 and 2.0GeV, as defined in the rest frame of the B-meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7GeV threshold we obtain the partial branching fraction BF(B to X_s gamma) = (3.45 +/- 0.15 +/- 0.40) x 10^-4, where the errors are statistical and systematic.Comment: 9 pages, 3 figures, 2 table