Wed·Oct 24, 2018Wednesday·October 24, 2018

1. 01*

   The $\tau$ Magnetic Dipole Moment at Future Lepton Colliders

   Jessica N. Howard🇺🇸 · Arvind Rajaraman🇺🇸 · Rebecca Riley🇺🇸 · Tim M. P. Tait🇺🇸

   The magnetic moment of the $\tau$ lepton is an interesting quantity that is potentially sensitive to physics beyond the Standard Model. Electroweak gauge invariance implies that a heavy new physics contribution to it takes the form of an operator which involves the Higgs boson, implying that rare Higgs decays are able to probe the same physics as $a_{\tau }$. We examine the prospects for rare Higgs decays at future high energy lepton (electron or muon) colliders, and find that such a project collecting a few ab${}^{-1}$ would be able to advance our understanding of this physics by roughly a factor of 10 compared to the expected reach of the high luminosity LHC.

   hep-phLHEP(2019)·11 citations
2. 02*

   Hadronic electroweak current and $\pi -a_1$ mixing

   A.A. Osipov🇷🇺 · B. Hiller🇵🇹 · P.M. Zhang🇨🇳

   It is found that in presence of electroweak interactions the gauge covariant diagonalization of the axial-vector -- pseudoscalar mixing in the effective meson Lagrangian leads to a deviation from the vector meson and the axial-vector meson dominance of the entire hadronic electroweak current. The essential features of such a modification of the theory are investigated in the framework of the extended Nambu-Jona-Lasinio model with explicit breaking of chiral $U(2)\times U(2)$ symmetry. The Schwinger-DeWitt method is used as a major tool in our study of the real part of the relevant effective action. Some straightforward applications are considered.

   hep-phPRD(2018)·5 citations
3. 03*

   Proton-philic spin-dependent inelastic Dark Matter (pSIDM) as a viable explanation of DAMA/LIBRA-phase2

   Sunghyun Kang🇰🇷 · Stefano Scopel🇰🇷 · Gaurav Tomar🇰🇷 · Jong-Hyun Yoon (Sogang U.)🇰🇷

   We show that the Weakly Interacting Massive Particle scenario of proton-philic spin-dependent inelastic Dark Matter (pSIDM) can still provide a viable explanation of the observed DAMA modulation amplitude in compliance with the constraints from other experiments after the release of the DAMA/LIBRA-phase2 data and including the recent bound from COSINE-100, that uses the same $NaI$ target of DAMA. The pSIDM scenario provided a viable explanation of DAMA/LIBRA--phase1 both for a Maxwellian WIMP velocity distribution and in a halo-independent approach. At variance with DAMA/LIBRA-phase1, for which the modulation amplitudes showed an isolated maximum at low energy, the DAMA/LIBRA-phase2 spectrum is compatible to a monotonically decreasing one. Moreover, due to its lower threshold, it is sensitive to WIMP-iodine interactions at low WIMP masses. Due to the combination of these two effects pSIDM can now explain the yearly modulation observed by DAMA/LIBRA only when the WIMP velocity distribution departs from a standard Maxwellian. In this case the WIMP mass $m_{\chi }$ and mass splitting $\delta$ fall in the approximate ranges 7 GeV $\lesssim m_{\chi }\lesssim$ 17 GeV and 18 keV$\lesssim \delta \lesssim$29 keV. The recent COSINE-100 bound is naturally evaded in the pSDIM scenario due to its large expected modulation fractions.

   hep-phastro-ph.COPRD(2019)·15 citations
4. 04*

   Production of the $Z_b^{(\prime )}$ states from the ${\rm Y}(5S,6S)$ decays

   Qi Wu🇨🇳 · Dian-Yong Chen🇨🇳 · Feng-Kun Guo🇨🇳

   In the present work, we investigate the production mechanism of the $Z_b(10610)$ and $Z_b(10650)$ states from the ${\rm Y}(5S,6S)$ decays. Two types of bottom-meson loops are discussed. We show that the loop contributions with all intermediate states being the $S$-wave ground state bottom mesons are negligible, while the loops with one bottom meson being the broad $B_0^{\ast }$ or $B_1^{\prime }$ resonance could provide the dominant contributions to the ${\rm Y}(5S)\to Z_b^{(\prime )}\pi$. It is found that such a mechanism is not suppressed by the large width of the $B_0/B_1^{\prime }$ resonance. In addition, we also estimate the branching ratios for the ${\rm Y}(6S)\to Z_b^{(\prime )}\pi$ which could be tested by future precise measurements at Belle-II.

   hep-phPRD(2019)·20 citations
5. 05*

   Revisiting the mechanical properties of the nucleon

   Cédric Lorcé🇫🇷 · Hervé Moutarde🇫🇷 · Arkadiusz P. Trawiński🇫🇷

   We discuss in detail the distributions of energy, radial pressure and tangential pressure inside the nucleon. In particular, this discussion is carried on in both the instant form and the front form of dynamics. Moreover we show for the first time how these mechanical concepts can be defined when the average nucleon momentum does not vanish. We express the conditions of hydrostatic equilibrium and stability in terms of these two and three-dimensional energy and pressure distributions. We briefly discuss the phenomenological relevance of our findings with a simple yet realistic model. In the light of this exhaustive mechanical description of the nucleon, we also present several possible connections between hadronic physics and compact stars, like e.g. the study of the equation of state for matter under extreme conditions and stability constraints.

   hep-phEPJC(2019)·271 citations
6. 06*

   Chiralspin symmetry and its implications for QCD

   L. Ya. Glozman🇦🇹

   In a local gauge-invariant theory with massless Dirac fermions a symmetry of the Lorentz-invariant fermion charge is larger than a symmetry of the Lagrangian as a whole. While the Dirac Lagrangian exhibits only a chiral symmetry, the fermion charge operator is invariant under a larger symmetry group, SU(2N_F), that includes chiral transformations as well as SU(2)_{CS} chiralspin transformations that mix the right- and left-handed components of fermions. Consequently a symmetry of the electric interaction, that is driven by the charge density, is larger than a symmetry of the magnetic interaction and of the kinetic term. This allows to separate in some situations electric and magnetic contributions. In particutar, in QCD the chromo-magnetic interaction contributes only to the near-zero modes of the Dirac operator, while confining chromo-electric interaction contributes to all modes. At high temperatures, above the chiral restoration crossover, QCD exhibits approximate SU(2)_{CS} and SU(2N_F) symmetries that are incompatible with free deconfined quarks. Consequently elementary objects in QCD in this regime are quarks with a definite chirality bound by the chromo-electric field, without the chromo-magnetic effects. In this regime QCD can be described as a stringy fluid.

   hep-phhep-lathep-thnucl-thUniverse(2019)·6 citations
7. 07*

   Production of strange particles in hadronic interactions

   A. Galoyan🇷🇺 · A. Ribon🇨🇭 · V. Uzhinsky🇷🇺

   The NA61/SHINE collaboration has recently published high precision data on production of ${\pi }^{\pm }$ and $K^{\pm }$ mesons, protons, antiprotons and $\Lambda$ hyperons in $\mathrm{pp}$ interactions at 20, 31, 40, 80 and 158 GeV/c, and in $\mathrm{pC}$ interactions at 31 GeV/c. The collaboration also presented experimental data on production of particles - ${\pi }^{\pm }$, $K^{\pm }$, $p^{\pm }$, ${\rho }^0$, $\omega$ and $K^{\ast 0}$ in ${\pi }^{-}\mathrm{C}$ collisions at 158 and 350 GeV/c. The collaboration has compared these data with various Monte Carlo model calculations: UrQMD, EPOS, GiBUU, and others. All of the models have various problems. The latest version of the FTF (Fritiof) model of Geant4 solves most of these problems. In the FTF model, we have improved the fragmentation of quark-gluon strings with small masses and introduced dependencies of probabilities of strange mesons and baryon-antibaryon pair's creation on string masses. Due to these changes, we describe the data of the NA61/SHINE collaboration on particle production in $\mathrm{pp},\mathrm{pC}$, and ${\pi }^{-}\mathrm{C}$ interactions. The improved Geant4 FTF model also well reproduces experimental data on inclusive cross sections of $\Lambda ,\bar{\Lambda }$ and $K^0$ production in antiproton-proton interactions at various energies. The modified FTF model allows one to simulate realistic processes with two particle productions - $\bar{p}p\to \Lambda \bar{\Lambda }$, $\bar{p}p\to K^{+}{K}^{-}$, $\bar{p}p\to \Lambda \bar{\Sigma }$, and $\bar{p}p\to \Sigma \bar{\Sigma }$, which will be studied in the future by the PANDA experiment at FAIR (GSI, Germany).

   hep-phnucl-thNucl.Theor.(2018)·1 citation
8. 08*

   Are there narrow flavor-exotic tetraquarks in large-$N_c$ QCD?

   Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇦🇹 · Hagop Sazdjian🇫🇷

   A salient feature shared by all tetraquark candidates observed in experiment is the absence of flavor-exotic states of the type $\bar{a}b\bar{c}d$, with four different quark flavors. This phenomenon may be understood from the properties of large-$N_c$ QCD: On the one hand, consistency conditions for flavor-exotic Green functions, potentially containing these tetraquark poles, require the existence of two tetraquarks $T_A$ and $T_B$: each of them should decay dominantly via a single two-meson channel, $T_A\to M_{\bar{a}b}{M}_{\bar{c}d}$ and $T_B\to M_{\bar{a}d}{M}_{\bar{c}b}$, with suppressed rates $T_A\to M_{\bar{a}d}{M}_{\bar{c}b}$ and $T_B\to M_{\bar{a}b}{M}_{\bar{c}d}$. On the other hand, we have at hand only one diquark-antidiquark flavor structure $(\bar{a}\bar{c})(bd)$ that might produce a compact tetraquark bound state. Taking into account that the diquark-antidiquark structure is the only viable candidate for a compact tetraquark state, one concludes that it is impossible to have two different narrow tetraquarks decaying dominantly into different two-meson channels. This contradiction suggests that large-$N_c$ QCD does not support the existence of narrow flavor-exotic tetraquarks. This argument does not rule out the possible existence of broad molecular-type flavor-exotic states, or of molecular-type bound states lying very close to the two-meson thresholds.

   hep-phPRD(2018)·21 citations
9. 09*

   Hyperon resonances coupled to pseudoscalar- and vector-baryon channels

   K. P. Khemchandani🇧🇷 · A. Martínez Torres🇧🇷 · J. A. Oller🇪🇸

   We study hyperon resonances by solving coupled channel scattering equations. The coupled systems include pseudoscalar- and vector-baryon channels. The parameters of the model are restricted by making a ${\chi }^2$-fit to the cross section data on processes: $K^{-}p\to K^{-}p$, $K^{-}p\to {\bar{K}}^{0}n$, $K^{-}p\to \eta \Lambda$, $K^{-}p\to {\pi }^0\Lambda$, $K^{-}p\to {\pi }^0{\Sigma }^0$, $K^{-}p\to {\pi }^{\pm }{\Sigma }^{\mp }$. Data on the energy level shift and width of the $1s$ state of the kaonic hydrogen, as well as some cross-section ratios near the threshold are also considered in the fit. Two types of fits are found as a result. In both cases, the properties of $\Lambda (1405)$ are well reproduced. In addition to this, a $\Sigma$ state is also found with mass around 1400 MeV. Cross sections, obtained with one of the two fits, are found to stay close to the data at energies away from the thresholds too, and as a result resonances with higher masses have also been studied.

   hep-phnucl-thPRC(2019)·40 citations
10. 10*

    Z boson production via p-p and Pb-Pb collisions at $\sqrt{s_{pp}}$=5.02 TeV

    Leonard S. Kisslinger🇺🇸 · Debasish Das🇮🇳

    We estimate the production of $Z^a$ bosons via p-p collisions using previous work on $J/\Psi$, $\Psi (2S)$ production in p-p collisions, with the new aspect being the creation of $Z^a$ bosons via quark interactions, with $a$ the component of a $Z$ vector boson. We then estimate the production of $Z^a$ bosons via Pb-Pb collisions using modification factors from previous publications.

    hep-phAdv.High Energy Phys.(2020)·0 citations
11. 11*

    Light and heavy flavor dijet production and dijet mass modification in heavy ion collisions

    Zhong-Bo Kang🇺🇸 · Jared Reiten🇺🇸 · Ivan Vitev🇺🇸 · Boram Yoon🇺🇸

    Back-to-back light and heavy flavor dijet measurements are promising experimental channels to accurately study the physics of jet production and propagation in a dense QCD medium. They can provide new insights into the path length, color charge, and mass dependence of quark and gluon energy loss in the quark-gluon plasma produced in reactions of ultra-relativistic nuclei. To this end, we perform a comprehensive study of both light and heavy flavor dijet production in heavy ion collisions. We propose the modification of dijet invariant mass distributions in such reactions as a novel observable that shows enhanced sensitivity to the QGP transport properties and heavy quark mass effects on in-medium parton showers. This is achieved through the addition of the jet quenching effects on the individual jets as opposed to their subtraction. The latter drives the subtle effects on more conventional observables, such as the dijet momentum imbalance shifts, which we also calculate here. Results are presented in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV for comparison to data at the Large Hadron Collider and in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV to guide the future sPHENIX program at the Relativistic Heavy Ion Collider.

    hep-phhep-exnucl-exnucl-thPRD(2019)·28 citations
12. 12*

    The Leptoquark Hunter's Guide: Large Coupling

    Martin Schmaltz🇺🇸 · Yi-Ming Zhong🇺🇸

    Leptoquarks have recently received much attention especially because they may provide an explanation to the $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies in rare $B$ meson decays. In a previous paper we proposed a systematic search strategy for all possible leptoquark flavors by focusing on leptoquark pair production. In this paper, we extend this strategy to large (order unity) leptoquark couplings which offer new search opportunities: single leptoquark production and $t$-channel leptoquark exchange with dilepton final states. We discuss the unique features of the different search channels and show that they cover complementary regions of parameter space. We collect and update all currently available bounds for the different flavor final states from LHC searches and from atomic parity violation measurements. As an application of our analysis, we find that current limits do not exclude the leptoquark explanation of the $B$ physics anomalies but that the high luminosity run of the LHC will reach the most interesting parameter space.

    hep-phhep-exJHEP(2019)·137 citations
13. 13*

    Infrared Finiteness and Forward Scattering

    Christopher Frye🇺🇸 · Holmfridur Hannesdottir🇺🇸 · Nisarga Paul🇺🇸 · Matthew D. Schwartz🇺🇸 · Kai Yan🇺🇸

    Infrared divergences have long been heralded to cancel in sufficiently inclusive cross-sections, according to the famous Kinoshita-Lee-Nauenberg theorem which mandates an initial and final state sum. While well-motivated, this theorem is much weaker than necessary: for finiteness, one need only sum over initial $\text{or}$ final states. Moreover, the cancellation generically requires the inclusion of the forward scattering process. We provide a number of examples showing the importance of this revised understanding: in $e^{+}{e}^{-}\to Z$ at next-to-leading order, one can sum over certain initial and final states with an arbitrary number of extra photons, or only over final states with a finite number of photons, if forward scattering is included. For Compton scattering, infrared finiteness requires the indistinguishability of hard forward-scattered electrons and photons. This implies that in addition to experimental limits on the energy and angular resolution, there must also be an experimental limit on the momentum at which electric charge can be observed. Similar considerations are required to explain why the rate for $\gamma \gamma$ to scatter into photons alone is infrared divergent but the rate for $\gamma \gamma$ to scatter into photons or charged particles is finite. This new understanding sheds light on the importance of including degenerate initial states in physical predictions, the relevance of disconnected Feynman diagrams, the importance of dressing initial or final-state charged particles, and the quest to properly define the $S$ matrix.

    hep-phPRD(2019)·60 citations
14. 14*

    $⟨x⟩$ and $⟨x^2⟩$ of the pion PDF from Lattice QCD with $N_f=2+1+1$ dynamical quark flavours

    M. Oehm🇩🇪 · C. Alexandrou🇨🇾 · M. Constantinou🇺🇸 · K. Jansen🇩🇪 · G. Koutsou🇨🇾 · B. Kostrzewa🇩🇪 · F. Steffens🇩🇪 · C. Urbach🇩🇪 · S. Zafeiropoulos🇩🇪

    Using Nf=2+1+1 lattice QCD, we determine the fermionic connected contributions to the second and third moment of the pion PDF. Based on gauge configurations from the European Twisted Mass Collaboration, chiral and continuum extrapolations are performed using pion masses in the range of 230 to 500 MeV and three values of the lattice spacing. Finite volume effects are investigated using different volumes. In order to avoid mixing under renormalisation for the third moment, we use an operator with two non-zero spatial components of momentum. Momenta are injected using twisted boundary conditions. Our final values read $⟨x⟩=0.2075(106)$ and $⟨x^2⟩=0.163(33)$, determined at 2 GeV in the $\overline{MS}$-scheme and with systematic and statistical uncertainties summend in quadrature.

    ↳ hep-lathep-exhep-phPRD(2019)·51 citations
15. 15*

    Simulation studies of ${\mathrm{R}}_2(\mathrm{\Delta }\eta ,\mathrm{\Delta }\phi )$ and ${\mathrm{P}}_2(\mathrm{\Delta }\eta ,\mathrm{\Delta }\phi )$ correlation functions in pp collisions with the PYTHIA and HERWIG models

    Baidyanath Sahoo🇮🇳 · Basanta Kumar Nandi🇮🇳 · Prabhat Pujahari🇮🇳 · Sumit Basu🇺🇸 · Claude Pruneau🇺🇸

    We report studies of charge-independent (CI) and charge-dependent (CD) two-particle differential-number correlation functions, ${\mathrm{R}}_2(\mathrm{\Delta }\eta ,\mathrm{\Delta }\phi )$, and transverse momentum ($p_{\mathrm{T}}$) correlation functions, ${\mathrm{P}}_2(\mathrm{\Delta }\eta ,\mathrm{\Delta }\phi )$, of charged particles in $\sqrt{\text{s}}$ = 2.76 TeV pp collisions with the PYTHIA and HERWIG models. Model predictions are presented for inclusive charged hadrons ($h^{\pm }$), as well as pions (${\pi }^{\pm }$), kaons (K${}^{\pm }$), and (anti-)protons ($\bar{\mathrm{p}}$/p) in the ranges $0.2<{\text{p}}_{\mathrm{T}}\le 2.0\mathrm{GeV}/\text{c}$, $2.0<{\text{p}}_{\mathrm{T}}\le 5.0\mathrm{GeV}/\text{c}$, and $5.0<{\text{p}}_{\mathrm{T}}\le 30.0\mathrm{GeV}/\text{c}$, with full azimuthal coverage in the range $|\eta |<1.0$. We compare the model predictions for the strength and shape of the ${\mathrm{R}}_2$ and ${\mathrm{P}}_2$ correlators as these pertain to recent measurements by the ALICE collaboration. The ${\mathrm{R}}_2$ and ${\mathrm{P}}_2$ correlation functions estimated with PYTHIA and HERWIG exhibit qualitatively similar near-side and away-side correlation structures but feature important differences. Our analysis indicates that comparative studies of ${\mathrm{R}}_2$ and ${\mathrm{P}}_2$ correlation functions would provide valuable insight towards the understanding of particle production in pp collisions, and by extension, should also be useful in studies of heavy-ion collisions. Comparison of the $\Delta \eta$ dependence of ${\mathrm{R}}_2$ and ${\mathrm{P}}_2$ could contribute, in particular, to a better understanding and modeling of the angular ordering of particles produced by hadronization in jets, as well as a better description of jet fragmentation functions of identified species at low momentum fraction $(z)$.

    ↳ nucl-exhep-exhep-phnucl-thPRC(2019)·13 citations
16. 16*

    2018 Update on ${\epsilon }_K$ with lattice QCD inputs

    Jon A. Bailey🇰🇷 · Sunkyu Lee🇰🇷 · Weonjong Lee · Yong-Chull Jang🇺🇸 · Jaehoon Leem🇰🇷 · Sungwoo Park🇺🇸

    We present updated results for ${\epsilon }_K$ determined directly from the standard model (SM) with lattice QCD inputs such as ${\hat{B}}_K$, $|V_{cb}|$, $|V_{us}|$, ${\xi }_0$, ${\xi }_2$, ${\xi }_{\text{LD}}$, $F_K$, and $m_c$. We find that the standard model with exclusive $|V_{cb}|$ and other lattice QCD inputs describes only 70% of the experimental value of $|{\epsilon }_K|$ and does not explain its remaining 30%, which leads to a strong tension in $|{\epsilon }_K|$ at the $4\sigma$ level between the SM theory and experiment. We also find that this tension disappears when we use the inclusive value of $|V_{cb}|$ obtained using the heavy quark expansion based on QCD sum rules.

    ↳ hep-lathep-phPoS(2018)·8 citations
17. 17*

    Neutrino recoil force in electron-capture decay of polarized nuclei: measurement prospects and potential applications

    A.L. Barabanov🇷🇺 · O.A. Titov🇷🇺

    Due to a directional asymmetry of neutrino emission caused by parity violation, a sample of radioactive atoms experiences a small recoil force from neutrino radiation accompanying electron capture by polarized nuclei. An expression for this force is obtained for the case of allowed nuclear transitions. Prospects to measure this force by the use of modern micromechanical devices are considered. Numerical estimates for the force are presented for a number of most suitable radioactive isotopes. Potential applications for the weak interaction studies are discussed including the possibility to search for hypothetical Lorentz invariance violation.

    ↳ nucl-thhep-phnucl-exPRC(2019)·3 citations
18. 18*

    Dwarf spheroidal $J$-factor likelihoods for generalized NFW profiles

    A. Chiappo🇸🇪 · J. Cohen-Tanugi🇫🇷 · J. Conrad🇸🇪 · L. E. Strigari🇺🇸

    Indirect detection strategies of particle Dark Matter (DM) in Dwarf spheroidal satellite galaxies (dSphs) typically entail searching for annihilation signals above the astrophysical background. To robustly compare model predictions with the observed fluxes of product particles, most analyses of astrophysical data -- which are generally frequentist -- rely on estimating the abundance of DM by calculating the so-called $\text{J-factor}$. This quantity is usually inferred from the kinematic properties of the stellar population of a dSph using Jeans equation, commonly by means of Bayesian techniques which entail the presence (and additional systematic uncertainty) of prior choice. Here, extending earlier work, we develop a scheme to derive the profile likelihood for $J$-factors of dwarf spheroidals for models with five or more free parameters. We validate our method on a publicly available simulation suite, released by the Gaia Challenge, finding satisfactory statistical properties for coverage and bias. We present the profile likelihood function and maximum likelihood estimates for the $J$-factor of ten dSphs . As an illustration, we apply these profiles likelihood to recently published analyses of gamma-ray data with the Fermi Large Area Telescope to derive new, consistent upper limits on the DM annihilation cross-section. We do this for a subset of systems, generally referred to as $\text{classical dwarfs}$. The implications of these findings for DM searches are discussed, together with future improvements and extensions of this technique.

    ↳ astro-ph.GAastro-ph.COastro-ph.HEhep-phMNRAS(2019)·14 citations
19. 19*

    Machine Learning Accelerated Likelihood-Free Event Reconstruction in Dark Matter Direct Detection

    U. Simola🇫🇮 · B. Pelssers🇸🇪 · D. Barge🇸🇪 · J. Conrad🇸🇪 · J. Corander🇫🇮

    Reconstructing the position of an interaction for any dual-phase time projection chamber (TPC) with the best precision is key to directly detecting Dark Matter. Using the likelihood-free framework, a new algorithm to reconstruct the 2-D (x; y) position and the size of the charge signal (e) of an interaction is presented. The algorithm uses the charge signal (S2) light distribution obtained by simulating events using a waveform generator. To deal with the computational effort required by the likelihood-free approach, we employ the Bayesian Optimization for Likelihood-Free Inference (BOLFI) algorithm. Together with BOLFI, prior distributions for the parameters of interest (x; y; e) and highly informative discrepancy measures to perform the analyses are introduced. We evaluate the quality of the proposed algorithm by a comparison against the currently existing alternative methods using a large-scale simulation study. BOLFI provides a natural probabilistic uncertainty measure for the reconstruction and it improved the accuracy of the reconstruction over the next best algorithm by up to 15% when focusing on events over a large radii (R > 30 cm, the outer 37% of the detector). In addition, BOLFI provides the smallest uncertainties among all the tested methods.

    ↳ astro-ph.IMhep-exhep-phphysics.data-an+1JINST(2019)·10 citations
20. 20*

    Splittings of low-lying charmonium masses at the physical point

    Carleton DeTar🇺🇸 · Andreas S. Kronfeld🇺🇸 · Song-haeng Lee🇺🇸 · Daniel Mohler🇩🇪 · James N. Simone🇺🇸

    We present high-precision results from lattice QCD for the mass splittings of the low-lying charmonium states. For the valence charm quark, the calculation uses Wilson-clover quarks in the Fermilab interpretation. The gauge-field ensembles are generated in the presence of up, down, and strange sea quarks, based on the improved staggered (asqtad) action, and gluon fields, based on the one-loop, tadpole-improved gauge action. We use five lattice spacings and two values of the light sea quark mass to extrapolate the results to the physical point. An enlarged set of interpolating operators is used for a variational analysis to improve the determination of the energies of the ground states in each channel. We present and implement a continuum extrapolation within the Fermilab interpretation, based on power-counting arguments, and thoroughly discuss all sources of systematic uncertainty. We compare our results for various mass splittings with their experimental values, namely, the 1S hyperfine splitting, the 1P-1S splitting and the P-wave spin-orbit and tensor splittings. Given the uncertainty related to the width of the resonances, we find excellent agreement.

    ↳ hep-lathep-phPRD(2019)·20 citations
21. 21*

    Controlling Excited-State Contributions with Distillation in Lattice QCD Calculations of Nucleon Isovector Charges $g_S^{u-d}$, $g_A^{u-d}$, $g_T^{u-d}$

    Colin Egerer🇺🇸 · David Richards🇺🇸 · Frank Winter🇺🇸

    We investigate the application of the distillation smearing approach, and the use of the variational method with an extended basis of operators facilitated by this approach, on the calculation of the nucleon isovector charges $g_S^{u-d}$, $g_A^{u-d}$, and $g_T^{u-d}$. We find that the better sampling of the lattice enabled through the use of distillation yields a substantial reduction in the statistical uncertainty in comparison with the use of alternative smearing methods, and furthermore, appears to offer better control over the contribution of excited-states compared to use of a single, local interpolating operator. The additional benefit arising through the use of the variational method in the distillation approach is less dramatic, but nevertheless significant given that it requires no additional Dirac inversions.

    ↳ hep-lathep-phnucl-thPRD(2019)·27 citations
22. 22*

    The Giant Radio Array for Neutrino Detection (GRAND): Science and Design

    GRAND Collaboration: Jaime Alvarez-Muniz (1)🇪🇸 · Rafael Alves Batista (2 and 3 and 4)🇧🇷 · Aswathi Balagopal V. (5)🇩🇪 · Julien Bolmont (6)🇫🇷 · Mauricio Bustamante (7 and 8 and 9 and 10)🇩🇰 · Washington R. Carvalho (2 and 1)🇪🇸 · Didier Charrier (11)🇫🇷 · Ismael Cognard (12 and 13)🇫🇷 · Valentin Decoene (14)🇫🇷 · Peter B. Denton (7 and 8)🇩🇰 · Sijbrand J. De Jong (15 and 16)🇳🇱 · Krijn D. De Vries (17)🇧🇪 and 38 other authors

    The Giant Radio Array for Neutrino Detection (GRAND) is a planned large-scale observatory of ultra-high-energy (UHE) cosmic particles, with energies exceeding 10^8 GeV. Its goal is to solve the long-standing mystery of the origin of UHE cosmic rays. To do this, GRAND will detect an unprecedented number of UHE cosmic rays and search for the undiscovered UHE neutrinos and gamma rays associated to them with unmatched sensitivity. GRAND will use large arrays of antennas to detect the radio emission coming from extensive air showers initiated by UHE particles in the atmosphere. Its design is modular: 20 separate, independent sub-arrays, each of 10 000 radio antennas deployed over 10 000 km^2. A staged construction plan will validate key detection techniques while achieving important science goals early. Here we present the science goals, detection strategy, preliminary design, performance goals, and construction plans for GRAND.

    ↳ astro-ph.HEhep-exhep-phSCPMA(2020)·468 citations
23. 23*

    The nature of core formation in dark matter haloes: adiabatic or impulsive?

    Jan D. Burger🇮🇸 · Jesús Zavala (University of Iceland)🇮🇸

    It is well established that the central deficit of dark matter (DM) observed in many dwarf galaxies disagrees with the cuspy DM haloes predicted in the collision-less and cold DM (CDM) model. Plausible solutions to this problem are based on an effective energy deposition into the central halo with an origin that is either based on baryonic physics (e.g. supernova-driven gas blowouts; SNF) or on new DM physics (e.g. self-interacting DM, SIDM). We argue that the fundamental difference between the two is whether the process is impulsive or adiabatic, and explore novel ways to distinguishing them by looking at the response of stellar orbits. We perform idealised simulations of tracers embedded in a $1.48\times 10^{10}{\mathrm{M}}_{\odot }$ spherical halo, and model the creation of a $\sim 1$kpc DM matter core in SIDM with ${\sigma }_T/m_{\chi }=2{\mathrm{cm}}^2{\mathrm{g}}^{-1}$ and through SNF by impulsively removing a mass equivalent to $\mathcal{O}(10\%)$ of the halo's potential energy. Choosing idealised initial orbital configurations for the tracers, we find that radial actions are conserved (changed) in the SIDM (impulsive) case. The adiabaticity of the SIDM case prevents tracers from changing their orbital family during core formation whereas SNF separates tracers of initially the same family to a variety of orbits. We show that these key features remain in a cosmological halo, albeit for a few dynamical timescales. The number density and velocity dispersion profile of a Plummer sphere with $r_{1/2}=500$ pc change only marginally under adiabatic core formation, whereas SNF causes a substantial expansion of the sphere driving it out of Jeans equilibrium. Our results point towards promising ways of differentiating adiabatic from impulsive core formation.

    ↳ astro-ph.GAhep-phMNRAS(2019)·22 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.