L. M. Garcia Martin
A5100633066- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Magnetic properties of thin films
- Dark Matter and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Computational Physics and Python Applications
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Magnetic Properties of Alloys
- Rare-earth and actinide compounds
- Medical Imaging Techniques and Applications
- Magnetic and transport properties of perovskites and related materials
- Theoretical and Computational Physics
- Superconducting Materials and Applications
- Nuclear physics research studies
- Stochastic processes and statistical mechanics
- Magnetic Properties and Applications
- Magnetic Properties and Synthesis of Ferrites
- Physics of Superconductivity and Magnetism
- Radiation Detection and Scintillator Technologies
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
École Polytechnique Fédérale de Lausanne
2023-2025
Czech Academy of Sciences, Institute of Physics
2025
University of Warwick
2020-2024
Rutherford Appleton Laboratory
2023
Universitat de València
2016-2021
Instituto de Física Corpuscular
2016-2021
University of Oxford
2008-2020
Instituto de Nanociencia y Materiales de Aragón
2008-2020
Universidad de Zaragoza
2009-2020
Universitat de Barcelona
2016-2020
A universal curve for the change in magnetic entropy has been recently proposed materials with second-order phase transitions. In this work we have studied behavior of magnetocaloric effect family cobalt Laves phases, $R{\text{Co}}_{2}$, and mixed manganites, ${\text{La}}_{2/3}{({\text{Ca}}_{x}{\text{Sr}}_{(1\ensuremath{-}x)})}_{1/3}{\text{MnO}}_{3}$, which exhibit first- The rescaled curves different applied fields collapse onto a single transition as opposed to first-order compounds, does...
We report the first determination of relative strong-phase difference between D^0 -> K^0_S,L K^+ K^- and D^0-bar K^-. In addition, we present updated measurements pi^+ pi^- pi^-. Both exploit quantum coherence a pair mesons produced from psi(3770) decays. The differences measured are important for determining Cabibbo-Kobayashi-Maskawa angle gamma/phi_3 in B^- D^0-tilde decays, where is or meson decaying to K^0_S h^+ h^- (h=pi,K), manner independent model assumed describe decay. Using our...
We study the magnetic properties of spherical Co clusters with diameters between 0.8 nm and 5.4 (25 to 7500$ atoms) prepared by sequential sputtering Al2O3. The particle size distribution has been determined from equilibrium susceptibility magnetization data it is compared previous structural characterizations. activation energies was independently obtained a scaling plot ac susceptibility. Combining these two distributions we have accurately effective anisotropy constant Keff. find that...
Using the entire CLEO-c \psi(3770)-> D\bar{D} event sample, corresponding to an integrated luminosity of $818 pb^-1 and approximately 5.4 million events, we present a study decays D^0 -> \pi^- e^+ \nu_e, K^- D^+ \pi^0 \bar{K}^0 \nu_e. Via tagged analysis technique, in which one D is fully reconstructed hadronic mode, partial rates for semileptonic by other are measured several q^2 bins. We fit these using form factor parameterizations report results, including shape parameters branching...
X-ray magnetic circular dichroism (XMCD) measured at $T=6\text{ }\text{K}$ and ${\ensuremath{\mu}}_{0}H=5\text{ }\text{T}$ on the $\ensuremath{\alpha}$-phase Fe-phthalocyanine (FePc) textured thin films shows that ${\text{Fe}}^{2+}$ ions present an unusually large, highly unquenched ${m}_{L}=0.53\ifmmode\pm\else\textpm\fi{}0.04\text{ }{\ensuremath{\mu}}_{B}$ orbital component, with planar anisotropy. The spin ${m}_{S}=0.64\ifmmode\pm\else\textpm\fi{}0.05\text{ intra-atomic dipolar ${m}_{T}$...
We measure the branching ratio of purely leptonic decay D+ meson with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 0.09)x10^(-4), using 818/pb data taken on psi(3770) resonance CLEO-c detector at CESR collider. use this determination to derive a value for pseudoscalar constant fD+, combining measurements lifetime and assuming |Vcd| |Vus|. find fD+ (205.8 8.5 2.5) MeV. The rate asymmetry [B(D+ nu)-B(D- mu- nu)]/[B(D+ nu)+B(D- nu)] 0.08 0.08, consistent no CP violation. also set...
The influence that dipole-dipole interactions exert on the dynamics of magnetization nanometer-sized Co clusters has been studied by means ac and dc susceptibility experiments. These grow in a quasiordered layered structure, where all relevant parameters can be tailored measured independently. Our data show without ambiguity magnetic relaxation becomes slower as degree interaction increases. effective activation energy increases linearly with number nearest neighbor clusters, evolving from...
The decays of $\ensuremath{\psi}(2S)$ into $\ensuremath{\gamma}p\overline{p}$, ${\ensuremath{\pi}}^{0}p\overline{p}$, and $\ensuremath{\eta}p\overline{p}$ have been studied with the CLEO-c detector using a sample $24.5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ events obtained from ${e}^{+}{e}^{\ensuremath{-}}$ annihilations at $\sqrt{s}=3686\text{ }\text{ }\mathrm{MeV}$. data show evidence for excitation several ${N}^{*}$ resonances in $p{\ensuremath{\pi}}^{0}$ $p\ensuremath{\eta}$ channels...
We examine e+e−→Ds−Ds*+ and Ds*−Ds+ interactions at 4170 MeV using the CLEO-c detector in order to measure decay constant fDs+ with good precision. Previously our measurements were substantially higher than most precise lattice based QCD calculation of (241±3) MeV. Here we use Ds+→ℓ+ν channel, where ℓ+ designates either a μ+ or τ+, when τ+→π+ν¯. Analyzing both modes independently, determine B(Ds+→μ+ν)=(0.565±0.045±0.017)%, B(Ds+→τ+ν)=(6.42±0.81±0.18)%. also analyze them simultaneously find...
A universal curve for the magnetic entropy change has been found to exist a variety of materials with second order phase transitions. We have studied whether this behavior magnetocaloric effect is maintained in first transition, including RCo2 Laves phases and mixed La2/3(CaxSr1−x)1/3MnO3 manganites, which present both ordering The rescaled curves different applied fields collapse onto single only transition. This may be used as criterion determining transitions from purely measurements.
Using e+e−→D−sD*+s and D*−sD+s interactions at 4170 MeV collected with the CLEO-c detector, we investigate semileptonic decays D+s→f0(980)e+ν D+s→ϕe+ν. By examining decay rates as functions of four-momentum transfer squared q2, measure ratio [dBdq2(D+s→f0(980)e+ν)B(f0→π+π−)]/[dBdq2(D+s→ϕe+ν)B(ϕ→K+K−)] q2 zero to be (42±11)%. This has been predicted equal rate [B(Bs→J/ψf0)B(f0→π+π−)]/[B(Bs→J/ψϕ)B(ϕ→K+K−)], thus indicating that CP eigenstate J/ψf0 could useful for measuring violation via Bs...
We report evidence for the ground state of bottomonium, eta_b(1S), in radiative decay Upsilon(3S) --> gamma eta_b e^+e^- annihilation data taken with CLEO III detector. Using 6 million decays, and assuming Gamma(eta_b) = 10 MeV/c^2, we obtain B(Upsilon(3S) eta_b) (7.1 +- 1.8 1.1) X 10^{-4}, where first error is statistical second systematic. The significance about 4 sigma. mass determined to be M(eta_b) 9391.8 6.6 2.0 which corresponds hyperfine splitting Delta M_{hf}(1S)_b 68.5 MeV/c^2. 9...
The magnetic anisotropy of Co clusters with diameters ranging from 1.1 nm to 4.5 turns out be significantly larger than in bulk and strongly increasing decreasing cluster size. dominating role the surface can used modify by changing electronic properties matrix surrounding clusters. We find that capping a metallic (Cu Au) layer enhances anisotropy, thus also stabilizing magnetization against thermal fluctuations. observed enhancement is attributed bonding 3d electrons conduction band layer,...
Differential scanning calorimetry experiments have been performed under magnetic field in $R{\mathrm{Co}}_{2}$ Laves phases compounds ($R=\mathrm{Pr}$, Nd, Tb, Dy, Ho, and Er). The thermodynamical nature of the ferromagnetic transitions $\mathrm{Pr}{\mathrm{Co}}_{2}$ $\mathrm{Nd}{\mathrm{Co}}_{2}$ is clarified, after controversy present literature about character their ordering transitions. magnetocaloric effect showing a first-order magnetostructural transition ($R=\mathrm{Dy}$, Er)...
Analyzing 600/pb of e+e- collisions at 4170 MeV center-of-mass energy with the CLEO-c detector, we measure branching fraction B(Ds+ -> tau+ nu)=(5.52\pm 0.57\pm 0.21)% using rho^+ anti-nu decay mode. Combining other CLEO measurements nu) determine pseudoscalar constant fDs = (259.7\pm 7.8\pm 3.4) consistent value obtained from our Ds+ mu+ nu measurement (257.6\pm 10.3\pm 4.3) MeV. these find a fDs=(259.0 \pm 6.2\pm 3.0) MeV, that differs most accurate prediction based on unquenched lattice...
We have studied the leptonic decay ${D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\nu}}_{\ensuremath{\tau}}$, via channel ${\ensuremath{\tau}}^{+}\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\nu}}_{e}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$, using a sample of tagged ${D}_{s}^{+}$ decays collected near ${D}_{s}^{*\ifmmode\pm\else\textpm\fi{}}{D}_{s}^{\ensuremath{\mp}}$ peak production energy in ${e}^{+}{e}^{\ensuremath{-}}$ collisions with CLEO-c detector....
Using data collected on the $\ensuremath{\psi}(3770)$ resonance and near ${D}_{s}^{*\ifmmode\pm\else\textpm\fi{}}{D}_{s}^{\ensuremath{\mp}}$ peak production energy by CLEO-c detector, we study decays of possible $D\ensuremath{\rightarrow}PP$ modes report measurements or upper limits all branching fractions for Cabibbo-favored, singly Cabibbo-suppressed, doubly Cabibbo-suppressed except involving ${K}_{L}^{0}$ (and ${D}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$)....
X-ray magnetic circular dichroism spectra have been recorded at the ${L}_{2,3}$ edges of Co, Cu, Ag, and Au, $K$ Co Cu for a series multilayer systems partially self-assembled nanoparticles, both capped with alumina different metals (Cu, Au). The orbital spin moments ${m}_{L}$ ${m}_{S}$ their ratio ${m}_{L}/{m}_{S}$, determined from those measurements. trend increasing ${m}_{L}/{m}_{S}$ is same as found effective anisotropy ${K}_{\text{eff}}$ $<\text{Cu}<\text{Ag}<\text{Au}$ capped. It shown...
X-ray absorption and x-ray magnetic circular dichroism (XMCD) spectra have been recorded at the Pt ${L}_{2,3}$ edges of ${\text{Pt}}_{13}$ hydrogenated ${\text{Pt}}_{13}{\text{H}}_{m}$ clusters dispersed in NaY zeolite. A foil was also measured as reference for comparison with bulk Pt. From near edge structure measurements average number holes ${n}_{h}$ $5d$ band these systems is found. In sample Pt-H antibonding state increases respect to sample. It gives rise a shape resonance energy...
Using 586pb^-1 of e^+e^- collision data at E_CM = 4170MeV, produced the CESR collider and collected with CLEO-c detector, we observe process --> pi^+ pi^- h_c(1P). We measure its cross section to be 15.6+-2.3+-1.9+-3.0pb, where third error is due external uncertainty on branching fraction psi(2S) pi^0 h_c(1P), which use for normalization. also find evidence eta h_c(1P) 4170MeV 3sigma level, see hints a rise in 4260MeV.
We exploit the quantum coherence between pair-produced D0 and D0B in psi(3770) decays to make a first determination of relative strong phase differences D0--> K0Spi+pi- D0B--> K0Spi+pi-, which are great importance determining CKM angle gamma/phi3 B- --> (D0B) K- decays. Using 818 1/pb e+e- collision data collected with CLEO-c detector at Ecm = 3.77 GeV, we employ binned Dalitz-plot analysis K0S pi+pi- K0Lpi+pi- recoiling against flavor-tagged, CP-tagged tagged events determine these differences.
The crossover from antidot to dot magnetic behavior on arrays patterned in a ferromagnetic thin film has been achieved by modifying only the geometry. A series of fabricated cobalt with fixed diameter $d$ and reducing period array $p$ $p\ensuremath{\gg}\phantom{\rule{4pt}{0ex}}d$ $p<d$. dramatic change coercivity dependence $p$, correlated significant modification domain structure observed x-ray photoemission electron microscopy, evidences crossover. An intermediate regime found between...
Permanent electric dipole moments (EDMs) of fundamental particles provide powerful probes for physics beyond the Standard Model. We propose to search EDM strange and charm baryons at LHC, extending ongoing experimental program on neutron, muon, atoms, molecules light nuclei. The $$\varLambda $$ baryons, selected from weak decays produced in $$p collisions can be determined by studying spin precession magnetic field detector tracking system. A test $$C\!PT$$ symmetry performed measuring...
Using data acquired with the CLEO-c detector at CESR e+e− collider, we measure branching fractions for J/ψ, ψ(2S), and ψ(3770) decays to γπ0, γη, γη′. Defining Rn≡B[ψ(nS)→γη]/B[ψ(nS)→γη′], obtain R1=(21.1±0.9)% and, unexpectedly, an order of magnitude smaller limit, R2<1.8% 90% C.L. We also use J/ψ→γη′ events determine improved precision five most copious η′ decay modes.Received 8 April 2009DOI:https://doi.org/10.1103/PhysRevD.79.111101©2009 American Physical Society