Search

Recently, several LQCD simulations have proven that the interaction in the isoscalar channel in $DD^*$ scattering is attractive. This channel is naturally connected to the $T_{cc}(3875)^+$ which is observed in the $D^0D^0\pi^+$ invariant mass distribution. However, it remains an open question whether the virtual bound state found in the several LQCD simulations is actually linked to the LHCb experimental observation. In this article we perform an EFT-based analysis of the LQCD data and demostrate that a proper chiral extrapolation leads to a $T_{cc}$ pole compatible with experiment. At the physical pion mass, we find a virtual bound state with a binding energy $\Delta E=-0.06 \left(^{+1.30}_{-2.20}\right) \left(^{+0.50}_{-1.11}\right)$. Moreover, we extract from a global analysis both, the light and heavy quark mass dependence of the $T_{cc}$ pole, and study the role of the $\rho$ and $\pi$ meson exchanges.

By solving the Lippmann-Schwinger equation, possible hadronic molecules in the $D^*\bar K$-$D\bar K^*$ coupled-channel system are investigated with the one-meson exchange potentials, where both vector and pseudoscalar mesons are considered as exchange particles. We find an S-wave virtual state with mass $M=2487$ MeV, and a resonance with $M=2759$ and width $\Gamma=18$ MeV. In the $D^* \bar K$ invariant mass distribution, the virtual state appears as a cusp at the $D^*\bar K$ threshold, while the resonance potentially manifests as a dip. In particular, we take into account the $D\bar K \pi$ three-body dynamics due to the on-shell pion exchange and the finite decay width for $\bar K^*$. Additionally, the SU(4) breaking effect in the coupling between charmed and light mesons is investigated in our work. Our results also indicate that the accurate measurement for the decay width of the $D\bar K^*$ resonance can help us to evaluate this effect in the future., Comment: 22 pages, 3 figures

Valley chiral kagom\'e networks can arise in various situations, like for example, in double-aligned graphene-hexagonal boron nitride and periodically strained graphene. Here, we construct a phenomenological scattering model based on the symmetries of the network to investigate the energy spectrum and magnetotransport in this system. Additionally, we consider the effects of a finite Rashba spin-orbit coupling on the transport properties of the kagom\'e network. We identify conditions where the interplay of the Rashba spin-orbit coupling and the geometry of the lattice results in a reduction of the periodicity of the magnetoconductance and characteristic sharp resonances. Moreover, we find a finite spin-polarization of the conductance, which could be exploited in spintronic devices., Comment: 15 pages, 13 figures, comments are welcome

Baryogenesis at the TeV scale from CP-violating decays of a massive particle requires some way to avoid the washouts from processes closely related to the existence of CP violation. It has been proposed that one way can be baryogenesis from three-body decays (instead of two-body decays). In this work we revisit this statement and show that, similarly to two-body-decay models, successful baryogenesis from three-body decays requires that the mass of the decaying particle be well above 10-100 TeV unless some other mechanism to avoid washouts is implemented., Comment: 5 pages, 2 figures

We determine the quark mass dependence - light and heavy - of the $D_{s0}^*(2317)$ and $D_{s1}(2460)$ properties, such as, mass, coupling to $DK$, scattering lengths and compositeness, from a global analysis of $DK$ energy levels from LQCD. In particular, we analyze the HSC energy levels for $DK$ scattering in $I=0$ for different boosts and two pion masses. The formalism is based in the local hidden-gauge interaction of Weinberg-Tomozawa type which respects chiral and heavy quark spin symmetries, supplemented by a term that takes into account the $D^{(*)}K$ coupling to a bare $c\bar{s}$ component. The isospin violating decay of the $D_{s0}^*(2317)\to D_{s}^+\pi^0$ is also evaluated.

The MUSE experiment at Paul Scherrer Institute will perform the first measurement of low-energy muon-proton elastic scattering (muon lab momenta 115-210 MeV) with the aim of determining the proton charge radius. We study the prospects for the proton radius extraction using the theoretical framework of Dispersively Improved Chiral Effective Field Theory (DI$\chi$EFT). It connects the proton radii with the finite-$Q^2$ behavior of the form factors through complex analyticity and enables the use of data up to $Q^2 \sim$ 0.1 GeV$^2$ for radius extraction. We quantify the sensitivity of the $\mu p$ cross section to the proton charge radius, the theoretical uncertainty of the cross section predictions, and the size of two-photon exchange corrections. We find that the optimal kinematics for radius extraction at MUSE is at momenta 210 MeV and $Q^2 \sim$ 0.05-0.08 GeV$^2$. We compare the performance of electron and muon scattering in the same kinematics. As a byproduct, we obtain explicit predictions for the $\mu p$ and $ep$ cross sections at MUSE as functions of the assumed value of the proton radius., Comment: 12 pages, 12 figures

Minimally twisted bilayer graphene in the presence of an interlayer bias develops a triangular network of valley chiral modes that propagate along the $AB/BA$ interfaces and scatter at the $AA$ regions. The low energy physics of the resulting network can be captured by means of a phenomenological scattering network model, allowing to calculate the energy spectrum and the magnetoconductance in a straightforward way. Although there is in general a good agreement between microscopic and phenomenological models, there are some aspects that have not been captured so far with the latter. In particular, the appearance of flatbands in the energy spectrum associated to a localized density of states at the $AA$ regions. To bring both approaches closer together, we modify the previous energy independent phenomenological model and add the possibility to scatter to a set of discrete energy levels at the $AA$ regions, yielding a $S$ matrix with energy dependent parameters. Furthermore, we investigate the impact of Coulomb repulsion in these regions on a mean-field level and discuss possible effects of decoherence due to elastic and inelastic cotunneling events., Comment: 15 pages, 7+2 figures, comments are welcome

We study the light and heavy quark mass dependence of the low-lying charmed mesons in the framework of one-loop HH$\chi$PT. The low energy constants are determined by analyzing the available lattice data from different LQCD simulations. Model selection tools are implemented to determine the relevant parameters as required by data with a higher precision. Discretization and other effects due to the charm quark mass setting are discussed.

We study the dependence of the $D_{s0}(2317)$ mass on the light quark mass through the analysis of data from QCD lattice simulations. Combining HH$\chi$PT and model selection tools as the LASSO method we fit the lattice data of the low-lying charmed mesons masses, obtaining their extrapolation to the physical point and extracting results for the quark mass dependence of the exotic resonances $D_{s0}(2317)$ and $D_{s1}(2460)$, taking as input the energy levels from a lattice simulation., Comment: The 39th International Symposium on Lattice Field Theory, August 2022

We propose a new platform to detect signatures of the presence of Majorana bound states (MBSs) in the Fraunhofer pattern of Josephson junctions featuring quantum spin Hall edge states on the normal part and Majorana bound states at the NS interfaces. We use a tight-binding model to demonstrate a drastic change in the periodicity of the Fraunhofer pattern when comparing trivial and non-trivial regimes. We explain these results in terms of the presence of additional parallel-spin electron-hole reflections, which due to the spin-momentum locking, occur as cross Andreev reflections, accumulating a different magnetic flux and yielding a change in the Fraunhofer periodicity. We show that this detection scheme exhibits some advantages compared to previous ones as it is robust against disorder, finite temperature and works in equilibrium. Furthermore, we introduce a scattering model that captures the main results of the microscopic calculations with MBSs and extend our discussion to the main differences found using accidental zero energy ABSs., Comment: 17 pages, 15 figures. Comments are welcome

We investigate transport in the network of valley Hall states that emerges in minimally twisted bilayer graphene under interlayer bias. To this aim, we construct a scattering theory that captures the network physics. In the absence of forward scattering, symmetries constrain the network model to a single parameter that interpolates between one-dimensional chiral zigzag modes and pseudo-Landau levels. Moreover, we show how the coupling of zigzag modes affects magnetotransport. In particular, we find that scattering between parallel zigzag channels gives rise to Aharonov-Bohm oscillations that are robust against temperature, while coupling between zigzag modes propagating in different directions leads to Shubnikov-de Haas oscillations that are smeared out at finite temperature., Comment: 5 + 9 pages, 5 + 8 figures. arXiv admin note: text overlap with arXiv:2003.08987

We construct a phenomenological scattering theory for the triangular network of valley Hall states that arises in twisted bilayer graphene under interlayer bias. Crucially, our network model includes scattering between different valley Hall states within the same valley and spin. We show that in the absence of forward scattering, symmetries reduce the network model to a single parameter that interpolates between a nested Fermi surface and flatbands, which can be understood in terms of one-dimensional chiral zigzag modes and closed triangular orbits, respectively. We demonstrate how unitarity and symmetry constrain the couplings between zigzag modes, which has important implications on the nature of interference oscillations observed in experiments., Comment: 5 + 4 pages, 6 + 4 figures

Motivated by recent experiments, we investigate the excitation energy of a proximitized Rashba wire in the presence of a position dependent pairing. In particular, we focus on the spectroscopic pattern produced by the overlap between two Majorana bound states that appear for values of the Zeeman field smaller than the value necessary for reaching the bulk topological superconducting phase. The two Majorana bound states can arise because locally the wire is in the topological regime. We find three parameter ranges with different spectral properties: crossings, anticrossings and asymptotic reduction of the energy as a function of the applied Zeeman field. Interestingly, all these cases have already been observed experimentally. Moreover, since an increment of the magnetic field implies the increase of the distance between the Majorana bound states, the amplitude of the energy oscillations, when present, gets reduced. The existence of the different Majorana scenarios crucially relies on the fact that the two Majorana bound states have distinct $k$-space structures. We develop analytical models that clearly explain the microscopic origin of the predicted behavior., Comment: 9 pages, 8 figures

We investigate theoretically the dynamics of a Josephson junction in the framework of the RSJ model. We consider a junction that hosts two supercurrrent contributions: a $2\pi$- and a $4\pi$-periodic in phase, with intensities $I_{2\pi}$ and $I_{4\pi}$ respectively. We study the size of the Shapiro steps as a function of the ratio of the intensity of the mentioned contributions, i.e. $I_{4\pi}/I_{2\pi}$. We provide detailed explanations where to expect clear signatures of the presence of the $4\pi$-periodic contribution as a function of the external parameters: the intensity AC-bias $I_\text{ac}$ and frequency $\omega_\text{ac}$. On the one hand, in the low AC-intensity regime (where $I_\text{ac}$ is much smaller than the critical current, $I_\text{c}$), we find that the non-linear dynamics of the junction allows the observation of only even Shapiro steps even in the unfavorable situation where $I_{4\pi}/I_{2\pi}\ll 1$. On the other hand, in the opposite limit ($I_\text{ac}\gg I_\text{c}$), even and odd Shapiro steps are present. Nevertheless, even in this regime, we find signatures of the $4\pi$-supercurrent in the beating pattern of the even step sizes as a function of $I_\text{ac}$., Comment: 10 pages, 9 figures; comments are welcome

We study the critical Josephson current flowing through a double quantum dot weakly coupled to two superconducting leads. We use analytical as well as numerical methods to investigate this setup in the limit of small and large bandwidth leads in all possible charging states, where we account for on-site interactions exactly. Our results provide clear signatures of nonlocal spin-entangled pairs, which support interpretations of recent experiments [Deacon, R. S. et al., Nat. Commun. 6, 7446 (2015)]. In addition, we find that the ground state with one electron on each quantum dot can undergo a tunable singlet-triplet phase transition in the regime where the superconducting gap in the leads is not too large, which gives rise to an additional new signature of nonlocal Cooper pair transport., Comment: 13 pages, 9 figures

Cooper pair splitting (CPS) is a process in which the electrons of naturally occurring spin-singlet pairs in a superconductor are spatially separated using two quantum dots. Here we investigate the evolution of the conductance correlations in an InAs CPS device in the presence of an external magnetic field. In our experiments the gate dependence of the signal that depends on both quantum dots continuously evolves from a slightly asymmetric Lorentzian to a strongly asymmetric Fano-type resonance with increasing field. These experiments can be understood in a simple three - site model, which shows that the nonlocal CPS leads to symmetric line shapes, while the local transport processes can exhibit an asymmetric shape due to quantum interference. These findings demonstrate that the electrons from a Cooper pair splitter can propagate coherently after their emission from the superconductor and how a magnetic field can be used to optimize the performance of a CPS device. In addition, the model calculations suggest that the estimate of the CPS efficiency in the experiments is a lower bound for the actual efficiency., Comment: 5 pages + 4 pages supplementary information

We report a first-principle theoretical study of the adiabatic decoherence undergone by a nuclear spin system in a solid, coupled to the phonon field through the dipolar interaction. The calculations are performed for a chain of weakly interacting 1/2-spin pairs, considered as an open quantum system in contact with a bosonic heat bath. By incorporating to the whole system Hamiltonian the fluctuations of the local dipolar energy produced by low frequency phonons, and assuming that this low energy fluctuations are adiabatic, we find that the spin dynamics can be described in closed form through a spin-boson model. The obtained results show that the coupling with the phonons destroy the spin coherence, and the efficiency of the process significantly depends on the complexity of the involved spin states. By using realistic values for the various parameters of the model, we conclude that this mechanism can be particularly efficient to degrade multi-spin coherences, when the number of `active' spins involved in a given coherence is high. In this way, we show that the spin coherence in the adiabatic regime can be noticeably affected by this mechanism., Comment: 15 pages, 2 figures

We derive the formulae for the cross section of J/Psi production in high energy pA and AA collisions taking into account the gluon saturation/color glass condensate effects. We then perform the numerical calculations of the corresponding nuclear modification factors and find a good agreement between our calculations and the experimental data on J/Psi production in dA collisions. We also observe that cold nuclear modification effects alone cannot describe the data on J/Psi production in AA collisions. Additional final state suppression (at RHIC) and enhancement (at LHC) mechanisms are required to explain the experimental observations., Comment: 11 pages, 6 figures

This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC., Comment: 547 pages, A report on the joint BNL/INT/Jlab program on the science case for an Electron-Ion Collider, September 13 to November 19, 2010, Institute for Nuclear Theory, Seattle; v2 with minor changes, matches printed version

We study the Richardson equations close to the critical values of the paring strength g_c where the occurrence of divergencies preclude numerical solutions. We derive a set of equations for determining the critical g values and the non-collapsing pair energies. Studying the behavior of the solutions close to the critical points, we develop a procedure to solve numerically the Richardson equations for arbitrary coupling strength., Comment: 10 pages, 2 figures

We have obtained optical (BVR, [OIII]5007 and Halpha), near infrared (JHK) imaging and long-slit optical spectroscopy for the Blue Compact Dwarf galaxy Mrk86 (NGC2537). In this paper, the first of two, we present optical-near- infrared colors and emission-line fluxes for the currently star-forming regions, intemediate aged starburst and underlying stellar population. We also describe the evolutionary synthesis models used in Paper II. The R and Halpha luminosity distributions of the galaxy star-forming regions show maxima at M_R=-9.5 and L_Halpha=10^37.3 erg s^-1. The underlying stellar population shows an exponential surface brigthness profile with central value, mu_E,0=21.5 mag arcsec^-2, and scale, alpha=0.88 kpc, both measured in the R-band image. In the galaxy outer regions, dominated by this component, no significant color gradients are observed. Finally, a set of evolutionary synthesis models have been developed, covering a wide range in metallicity and burst strength., Comment: 21 pages, 14 figures, 2 landscape tables, accepted for publication in Astronomy & Astrophysics Supplement Series, for higher resolution images see ftp://cutrex.fis.ucm.es/pub/OUT/gil/PAPERS/aa00_I.ps.gz