Wed·May 3, 2017Wednesday·May 3, 2017

1. 01*

   Non-standard interactions of solar neutrinos in dark matter experiments

   Bhaskar Dutta🇺🇸 · Shu Liao🇺🇸 · Louis E. Strigari🇺🇸 · Joel W. Walker🇺🇸

   Non-standard neutrino interactions (NSI) affect both their propagation through matter and their detection, with bounds on NSI parameters coming from various astrophysical and terrestrial neutrino experiments. In this paper, we show that NSI can be probed in future direct dark matter detection experiments through both elastic neutrino-electron scattering and coherent neutrino-nucleus scattering, and that these channels provide complementary probes of NSI. We show NSI can increase the event rate due to solar neutrinos, with a sharp increase for lower nuclear recoil energy thresholds that are within reach for upcoming detectors. We also identify an interference range of NSI parameters for which the rate is reduced by approximately 40\%. Finally, we show that the "dark side" solution for the solar neutrino mixing angle may be discovered at forthcoming direct detection experiments.

   hep-phastro-ph.HEPLB(2017)·77 citations
2. 02*

   Axions, Instantons, and the Lattice

   Michael Dine🇺🇸 · Patrick Draper🇺🇸 · Laurel Stephenson-Haskins🇺🇸 · Di Xu🇺🇸

   If the QCD axion is a significant component of dark matter, and if the universe was once hotter than a few hundred MeV, the axion relic abundance depends on the function $\chi (T)$, the temperature-dependent topological susceptibility. Uncertainties in this quantity induce uncertainties in the axion mass as a function of the relic density, or vice versa. At high temperatures, theoretical uncertainties enter through the dilute instanton gas computation, while in the intermediate and strong coupling regime, only lattice QCD can determine $\chi (T)$ precisely. We reassess the uncertainty on the instanton contribution, arguing that it amounts to less than $20\%$ in the effective action, or a factor of 20 in $\chi$ at $T=1.5$ GeV. We then combine the instanton uncertainty with a range of models for $\chi (T)$ at intermediate temperatures and determine the impact on the axion relic density. We find that for a given relic density and initial misalignment angle, the combined uncertainty amounts to a factor of 2-3 in the zero-temperature axion mass.

   hep-phastro-ph.COhep-exhep-latPRD(2017)·78 citations
3. 03*

   Theories of Leptonic Flavor

   Claudia Hagedorn🇩🇰

   I discuss different theories of leptonic flavor and their capability of describing the features of the lepton sector, namely charged lepton masses, neutrino masses, lepton mixing angles and leptonic (low and high energy) CP phases. In particular, I show examples of theories with an abelian flavor symmetry G_f, with a non-abelian G_f as well as theories with non-abelian G_f and CP.

   hep-ph8 citations
4. 04*

   Polyakov loop modeling for hot QCD

   Kenji Fukushima🇯🇵 · Vladimir Skokov🇺🇸

   We review theoretical aspects of quantum chromodynamics (QCD) at finite temperature. The most important physical variable to characterize hot QCD is the Polyakov loop, which is an approximate order parameter for quark deconfinement in a hot gluonic medium. Additionally to its role as an order parameter, the Polyakov loop has rich physical contents in both perturbative and non-perturbative sectors. This review covers a wide range of subjects associated with the Polyakov loop from topological defects in hot QCD to model building with coupling to the Polyakov loop.

   hep-phhep-lathep-thnucl-thPPNP(2017)·167 citations
5. 05*

   Measuring the Higgsplosion Yield: Counting Large Higgs Multiplicities at Colliders

   James S. Gainer🇺🇸

   Recent work has brought renewed attention to the possibility that the cross section for producing $n$ Higgs bosons grows large with $n$ at a sufficiently energetic hadron collider. In particular, this "Higgsplosion'" mechanism has been suggested as a solution to the hierarchy problem. We investigate the phenomenology of this scenario. Discovery is trivial, so we consider several variables for use in measuring large Higgs multiplicities and evaluate their effectiveness. We find that a $10$% level measurement of the number of Higgs bosons is possible with a handful of events, using the scalar sum of jet transverse momenta, but determining the exact multiplicity may take a few thousand events, depending on the degree of statistical significance desired for the measurement. While this situation may be acceptable given the potentially large cross sections in this scenario, future research to improve the measurement is warranted.

   hep-phhep-ex9 citations
6. 06*

   Triple collinear emissions in parton showers

   Stefan Höche🇺🇸 · Stefan Prestel🇺🇸

   A framework to include triple collinear splitting functions into parton showers is presented, and the implementation of flavor-changing NLO splitting kernels is discussed as a first application. The correspondence between the Monte-Carlo integration and the analytic computation of NLO DGLAP evolution kernels is made explicit for both timelike and spacelike parton evolution. Numerical simulation results are obtained with two independent implementations of the new algorithm, using the two independent event generation frameworks Pythia and Sherpa.

   hep-phPRD(2017)·110 citations
7. 07*

   Multiparticle collectivity from initial state correlations in high energy proton-nucleus collisions

   Kevin Dusling🇺🇸 · Mark Mace🇺🇸 · Raju Venugopalan🇺🇸

   Qualitative features of multiparticle correlations in light-heavy ion ($p+A$) collisions at RHIC and LHC are reproduced in a simple initial state model of partons in the projectile coherently scattering off localized domains of color charge in the heavy nuclear target. These include i) the ordering of the magnitudes of the azimuthal angle $n$th Fourier harmonics of two-particle correlations $v_n\{2\}$, ii) the energy and transverse momentum dependence of the four-particle Fourier harmonic $v_2\{4\}$, and iii) the energy dependence of four-particle symmetric cumulants measuring correlations between different Fourier harmonics. Similar patterns are seen in an Abelian version of the model, where we observe $v_2\{2\}>v_2\{4\}\approx v_2\{6\}\approx v_2\{8\}$ of two, four, six, and eight particle correlations. While such patterns are often interpreted as signatures of collectivity arising from hydrodynamic flow, our results provide an alternative description of the multiparticle correlations seen in $p+A$ collisions.

   hep-phnucl-exnucl-thPRL(2018)·100 citations
8. 08*

   Asymptotic freedom in certain $SO(N)$ and $SU(N)$ models

   Martin B Einhorn🇺🇸 · D R Timothy Jones🇺🇸

   We calculate the $\beta$-functions for $SO(N)$ and $SU(N)$ gauge theories coupled to adjoint and fundamental scalar representations, correcting long-standing, previous results. We explore the constraints on $N$ resulting from requiring asymptotic freedom for all couplings. When we take into account the actual allowed behavior of the gauge coupling, the minimum value of $N$ in both cases turns out to be larger than realized in earlier treatments. We also show that in the large $N$ limit, both models have large regions of parameter space corresponding to total asymptotic freedom.

   hep-phhep-thPRD(2017)·14 citations
9. 09*

   Realization of a spontaneous gauge and supersymmetry breaking vacuum

   Tatsuo Kobayashi🇯🇵 · Yuji Omura🇯🇵 · Osamu Seto🇯🇵 · Kazuki Ueda🇯🇵

   It is one of the major issues to realize a vacuum which breaks supersymmetry (SUSY) and R-symmetry, in a supersymmetric model. We study the model, where the same sector breaks the gauge symmetry and SUSY. In general, the SUSY breaking model without gauge symmetry has a flat direction at the minimum of F-term scalar potential. When we introduce U(1) gauge symmetry to such a SUSY breaking model, there can appear a runaway direction. Such a runway direction can be lifted by loop effects, and the gauge symmetry breaking and SUSY breaking are realized. The R-symmetry, that is assigned to break SUSY, is also spontaneously broken at the vacuum. This scenario can be extended to non-Abelian gauge theories. We also discuss application to the Pati-Salam model and the SU(5) grand unified theory. We see that non-vanishing gaugino masses are radiatively generated by the R-symmetry breaking and the gauge messenger contribution.

   hep-phhep-thJHEP(2017)·9 citations
10. 10*

    Neutrino physics from A to Z : two lectures at Corfu

    J. W. F. Valle🇪🇸

    Assuming basic familiarity with neutrino physics, I give a telegraphic and panoramic view of the current status and the main open challenges in the field. I also illustrate how the mechanism responsible for neutrino mass generation may shed light upon some of the current puzzles in particle physics as well as cosmology

    hep-phPoS(2017)·5 citations
11. 11*

    Can a spontaneous collapse in flavour oscillations be tested at KLOE?

    K. Simonov🇦🇹 · B.C. Hiesmayr🇦🇹

    Why do we never see a table in a superposition of here and there? This problem gets a solution by so called collapse models assuming the collapse as a genuinely physical process. Here we consider two specific collapse models and apply them to systems at high energies, i.e. flavour oscillating neutral meson systems. We find on one hand a potentially new interpretation of the decay rates introduced by hand in the standard formalism and on the other hand that these systems at high energies constrain by experimental data the possible collapse scenarios.

    hep-phquant-phEPJ Web Conf.(2018)·6 citations
12. 12*

    $U(1{)}_{B_3-3L_{\mu }}$ gauge symmetry as a simple description of $b\to s$ anomalies

    Cesar Bonilla🇪🇸 · Tanmoy Modak🇹🇼 · Rahul Srivastava🇪🇸 · Jose W.F. Valle🇪🇸

    We present a simple $U(1{)}_{B_3-3L_{\mu }}$ gauge Standard Model extension that can easily account for the anomalies in $R(K)$ and $R(K^{\ast })$ reported by LHCb. The model is economical in its setup and particle content. Among the Standard Model fermions, only the third generation quark family and the second generation leptons transform non-trivially under the new $U(1{)}_{B_3-3L_{\mu }}$ symmetry. This leads to lepton non-universality and flavor changing neutral currents involving the second and third quark families. We discuss the relevant experimental constraints and some implications.

    hep-phhep-exPRD(2018)·126 citations
13. 13*

    Neutrinoless double beta decay and lepton flavour violation in broken $\mu -\tau$ symmetric neutrino mass models

    Happy Borgohain🇮🇳 · Mrinal Kumar Das🇮🇳

    We have studied neutrinoless double beta decay and charged lepton flavour violation in broken $\mu -\tau$ symmetric neutrino masses in a generic left-right symmetric model (LRSM). The leading order $\mu -\tau$ symmetric mass matrix originates from the type I (II) seesaw mechanism, whereas the perturbations to $\mu -\tau$ symmetry in order for generation of non-zero reactor mixing angle ${\theta }_{13}$, as required by latest neutrino oscillation data, originates from the type II (I) seesaw mechanism. In our work, we considered four different realizations of $\mu -\tau$ symmetry, viz. Tribimaximal Mixing (TBM), Bimaximal Mixing (BM), Hexagonal Mixing (HM) and Golden Ratio Mixing (GRM). We then studied the new physics contributions to neutrinoless double beta decay (NDBD) ignoring the left-right gauge boson mixing and the heavy-light neutrino mixing within the framework of LRSM. We have considered the mass of the gauge bosons and scalars to be around TeV and studied the effects of the new physics contributions on the effective mass and the NDBD half life and compared with the current experimental limit imposed by KamLAND-Zen. We further extended our analysis by correlating the lepton flavour violation of the decay processes, $\left(\mu \to 3e\right)$ and $\left(\mu \to e\gamma \right)$ with the lightest neutrino mass and atmospheric mixing angle ${\theta }_{23}$ respectively.

    hep-phInt.J.Theor.Phys.(2017)·18 citations
14. 14*

    On the Importance of Electroweak Corrections for B Anomalies

    Ferruccio Feruglio🇮🇹 · Paride Paradisi🇮🇹 · Andrea Pattori🇮🇹

    The growing experimental indication of Lepton Flavour Universality Violation (LFUV) both in charged- and neutral-current semileptonic B-decays, has triggered many theoretical interpretations of such non-standard phenomena. Focusing on popular scenarios where the explanation of these anomalies requires New Physics at the TeV scale, we emphasise the importance of including electroweak corrections to obtain trustable predictions for the models in question. We find that the most important quantum effects are the modifications of the leptonic couplings of the W and Z vector bosons and the generation of a purely leptonic effective Lagrangian. As a result, the tight experimental bounds on Z-pole observables and tau decays challenge an explanation of the current non-standard data. We illustrate how these effects arise, by providing a detailed discussion of the running and matching procedure which is necessary to derive the low-energy effective Lagrangian.

    hep-phhep-exJHEP(2017)·176 citations
15. 15*

    Determinations of $|V_{cb}|$ and $|V_{ub}|$ from baryonic ${\Lambda }_b$ decays

    Y.K. Hsiao🇨🇳 · C.Q. Geng🇨🇳

    We extract the Cabibbo-Kobayashi-Maskawa matrix element $V_{cb}$ from the exclusive decays of ${\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell }$ and ${\Lambda }_b\to {\Lambda }_c{M}_{(c)}$ with $M=({\pi }^{-},K^{-})$ and $M_c=(D^{-},D_s^{-})$, where the branching ratios of ${\Lambda }_b\to \Lambda M_{(c)}$ measured with high precisions have not been used in the previous studies. Explicitly, we find $|V_{cb}|=(44.0\pm 3.5)\times 10^{-3}$, which agrees with the value of $(42.11\pm 0.74)\times 10^{-3}$ from the inclusive $B\to X_c\ell {\bar{\nu }}_{\ell }$ decays. Furthermore, based on the most recent ratio of $|V_{ub}|/|V_{cb}|$ from the exclusive ${\Lambda }_b$ decays, we obtain $|V_{ub}|=(4.2\pm 0.4)\times 10^{-3}$, which is close to the value of $(4.49\pm 0.24)\times 10^{-3}$ from the inclusive $B\to X_u\ell {\bar{\nu }}_{\ell }$ decays. We conclude that our determinations of $|V_{cb}|$ and $|V_{ub}|$ from the exclusive ${\Lambda }_b$ decays favor the inclusive extractions in the $B$ decays.

    hep-phhep-exEPJC(2017)·7 citations
16. 16*

    Fermion stabilisation of extra dimensions and natural mass hierarchies

    Ian G. Moss🇬🇧

    Casimir forces from fermions in an extra dimension can stabilise Randall-Sundrum models. Contrary to previous expectations, the stabilisation can produce large electroweak hierarchies without fine tuning. The Casimir stabilisation occurs in the same five-dimensional fermion models which have been found to give the observed fermion mass hierarchies. This is shown for masses generated by the Higgs mechanism and by a Higgsless symmetry breaking mechanism, where new light Kaluza-Klein states are presented

    hep-phhep-th0 citations
17. 17*

    Implementing NLO DGLAP evolution in Parton Showers

    Stefan Höche🇺🇸 · Frank Krauss🇬🇧 · Stefan Prestel🇺🇸

    We present a parton shower which implements the DGLAP evolution of parton densities and fragmentation functions at next-to-leading order precision up to effects stemming from local four-momentum conservation. The Monte-Carlo simulation is based on including next-to-leading order collinear splitting functions in an existing parton shower and combining their soft enhanced contributions with the corresponding terms at leading order. Soft double counting is avoided by matching to the soft eikonal. Example results from two independent realizations of the algorithm, implemented in the two event generation frameworks Pythia and Sherpa, illustrate the improved precision of the new formalism.

    hep-phJHEP(2017)·108 citations
18. 18*

    Scotogenic model with $B-L$ symmetry and exotic neutrinos

    A. C. B. Machado🇧🇷 · J. Montano🇧🇷 · V. Pleite🇧🇷 · M. C. Rodriguez🇧🇷

    We consider a model with three Higgs doublet in a discrete $B-L\times {\mathbb{Z}}_3$ discrete symmetries. Two of the scalar doublets are inert due to the ${\mathbb{Z}}_3$ symmetry. We calculated all the mass spectra in the scalar and lepton sectors and accommodate the leptonic mixing matrix as well.

    hep-ph1 citation
19. 19*

    Higgs mediated CLFV processes $\mu N(eN)\to \tau X$ via gluon operators

    Michihisa Takeuchi🇯🇵 · Yuichi Uesaka🇯🇵 · Masato Yamanaka🇯🇵

    We revisit charged lepton flavor violating (CLFV) scattering processes ${\ell }_{i}N\to \tau X({\ell }_i\ni e,\mu )$ mediated by Higgs. We point out that a new subprocess ${\ell }_{i}g\to \tau g$ via the effective interactions of Higgs and gluon gives the dominant contribution to ${\ell }_{i}N\to \tau X$ for an incident beam energy of $E_{\ell }\lesssim 1\text{TeV}$ in fixed target experiments. Furthermore, in the light of quark number conservation, we consider quark pair-production processes ${\ell }_{i}g\to \tau q\bar{q}$ ($q$ denotes quarks) instead of ${\ell }_{i}q\to \tau q$. This corrects the threshold energy of each subprocess contributing to $\sigma ({\ell }_{i}N\to \tau X)$. Reevaluation of $\sigma ({\ell }_{i}N\to \tau X)$ including all of relevant subprocesses shows that the search for ${\ell }_{i}N\to \tau X$ could serve a complementary opportunity with other relevant processes to shed light on the Higgs CLFV.

    hep-phhep-exPLB(2017)·20 citations
20. 20*

    Differentiating $U(1{)}^{\prime }$ supersymmetric models with right sneutrino and neutralino dark matter

    Jack Y. Araz🇨🇦 · Mariana Frank🇨🇦 · Benjamin Fuks🇫🇷

    We perform a detailed analysis of dark matter signals of supersymmetric models containing an extra $U(1{)}^{\prime }$ gauge group. We investigate scenarios in which either the right sneutrino or the lightest neutralino are phenomenologically acceptable dark matter candidates and we explore the parameter spaces of different supersymmetric realisations featuring an extra $U(1{)}^{\prime }$. We impose consistency with low energy observables, with known mass limits for the superpartners and $Z^{\prime }$ bosons, as well as with Higgs boson signal strengths, and we moreover verify that predictions for the anomalous magnetic moment of the muon agree with the experimental value and require that the dark matter candidate satisfies the observed relic density and direct and indirect dark matter detection constraints. For the case where the sneutrino is the dark matter candidate, we find distinguishing characteristics among different $U(1{)}^{\prime }$ mixing angles. If the neutralino is the lightest supersymmetric particle, its mass is heavier than that of the light sneutrino in scenarios where the latter is a dark matter candidate, the parameter space is less restricted and differentiation between models is more difficult. We finally comment on the possible collider tests of these models.

    hep-phPRD(2017)·14 citations
21. 21*

    Enhancing Dark Matter Annihilation Rates with Dark Bremsstrahlung

    Nicole F. Bell🇦🇺 · Yi Cai🇦🇺 · James B. Dent🇺🇸 · Rebecca K. Leane🇦🇺 · Thomas J. Weiler🇺🇸

    Many dark matter interaction types lead to annihilation processes which suffer from p-wave suppression or helicity suppression, rendering them subdominant to unsuppressed s-wave processes. We demonstrate that the natural inclusion of dark initial state radiation can open an unsuppressed s-wave annihilation channel, and thus provide the dominant dark matter annihilation process for particular interaction types. We illustrate this effect with the bremsstrahlung of a dark spin-0 or dark spin-1 particle from fermionic dark matter, $\overline{\chi }\chi \to \overline{f}f\varphi$ or $\overline{f}f{Z}^{\prime }$. The dark initial state radiation process, despite having a 3-body final state, proceeds at the same order in the new physics scale $\Lambda$ as the annihilation to the 2-body final state $\overline{\chi }\chi \to \overline{f}f$. This is lower order in $\Lambda$ than the well-studied lifting of helicity suppression via Standard Model final state radiation, or virtual internal bremsstrahlung. This dark bremsstrahlung process should influence LHC and indirect detection searches for dark matter.

    hep-phastro-ph.COPRD(2017)·44 citations
22. 22*

    Bounding milli-magnetically charged particles with magnetars

    Anson Hook🇺🇸 · Junwu Huang🇺🇸

    Milli-magnetically charged particles generically appear in scenarios with kinetic mixing. We present model independent bounds on these particles coming from magnetars. Schwinger pair production discharges the magnetic field of the magnetar. Thus the existence of large magnetic fields at magnetars place strong bounds on the milli-magnetic charge to be smaller than $10^{-18}$ over a large mass range.

    hep-phastro-ph.HEhep-thPRD(2017)·44 citations
23. 23*

    Supernovae in SuperK-Gd and other experiments

    Lluis Marti-Magro🇯🇵

    Core-collapse supernovae are one of the most energetic events in the universe ($10^{46}J$). When a massive star (M $>$ 8 M${}_{\odot }$) ignites its last fusion stage where silicon fusion makes iron, its end is then very close. Basically, the core of the star falls inwardly and the gravitational energy is then released in a supernova explosion. The basic picture of this explosion was confirmed by the few neutrinos detected from the SN1987a supernova at Kamiokande, IMB and Baksan detectors. However, there are many details that are still unknown. Since then, a large detector network has grown with better capabilities. Nowadays, in the case of a supernova explosion in our galaxy, the information that we would acquire would allow us to learn much more about these energetic events and constrain our models. Here, I present a brief summary of this network with special emphasis in SuperK-Gd (the upgraded Super-Kamiokande detector with efficient neutron tagging).

    ↳ hep-exastro-ph.HEhep-phphysics.ins-det0 citations
24. 24*

    Photon production spectrum above $T_c$ with a lattice quark propagator

    Taekwang Kim🇯🇵 · Masayuki Asakawa🇯🇵 · Masakiyo Kitazawa🇯🇵

    The photon production rate from the deconfined medium is analyzed with the photon self-energy constructed from the quark propagator obtained by the numerical simulation on the quenched lattice for two values of temperature, $T=1.5T_{\mathrm{c}}$ and $3T_{\mathrm{c}}$, above the critical temperature $T_{\mathrm{c}}$. The photon self-energy is calculated by the Schwinger-Dyson equation with the lattice quark propagator and a vertex function determined so as to satisfy the Ward-Takahashi identity. The obtained photon production rate exhibits a similar behavior as the perturbative results at the energy of photons larger than $0.5$~GeV.

    ↳ nucl-thhep-phPTEP(2018)·0 citations
25. 25*

    Prospects for indirect MeV Dark Matter detection with Gamma Rays in light of Cosmic Microwave Background Constraints

    Alma X. Gonzalez-Morales🇲🇽 · Stefano Profumo🇺🇸 · Javier Reynoso-Córdova🇲🇽

    The self-annihilation of dark matter particles with mass in the MeV range can produce gamma rays via prompt or secondary radiation. The annihilation rate for such light dark matter particles is however tightly constrained by cosmic microwave background (CMB) data. Here we explore the possibility of discovering MeV dark matter annihilation with future MeV gamma-ray telescopes taking into account the latest and future CMB constraints. We study the optimal energy window as a function of the dominant annihilation final state. We consider both the (conservative) case of the dwarf spheroidal galaxy Draco and the (more optimistic) case of the Galactic center. We find that for certain channels, including those with one or two monochromatic photon(s) and one or two neutral pion(s), a detectable gamma-ray signal is possible for both targets under consideration, and compatible with CMB constraints. For other annihilation channels, however, including all leptonic annihilation channels and two charged pions, CMB data rule out any significant signal of dark matter annihilation at future MeV gamma-ray telescopes from dwarf galaxies, but possibly not for the Galactic center.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2017)·24 citations
26. 26*

    Possibility to probe negative values of a Wigner function in scattering of a coherent superposition of electronic wave packets by atoms

    Dmitry V. Karlovets🇷🇺 · Valeriy G. Serbo🇷🇺

    Within a plane-wave approximation in scattering, an incoming wave packet's Wigner function stays everywhere positive, which obscures such purely quantum phenomena as non-locality and entanglement. With the advent of the electron microscopes with subnanometer-sized beams one can enter a genuinely quantum regime where the latter effects become only moderately attenuated. Here we show how to probe negative values of the Wigner function in scattering of a coherent superposition of two Gaussian packets with a non-vanishing impact-parameter between them (a Schrödinger's cat state) by atomic targets. For hydrogen in the ground $1s$ state, a small parameter of the problem, a ratio $a/{\sigma }_{\perp }$ of the Bohr radius $a$ to the beam width ${\sigma }_{\perp }$, is no longer vanishing. We predict an azimuthal asymmetry of the scattered electrons, which is found to be up to $10\%$ and argue that it can be reliably detected. Production of beams with the not-everywhere positive Wigner functions and probing such quantum effects can open new perspectives for non-invasive electron microscopy, quantum tomography, particle physics, etc.

    ↳ quant-phhep-phphysics.atom-phPRL(2017)·15 citations
27. 27*

    Chiral behavior of $K\to \pi l\nu$ decay form factors in lattice QCD with exact chiral symmetry

    JLQCD Collaboration: S. Aoki🇯🇵 · G. Cossu🇬🇧 · X. Feng🇨🇳 · H. Fukaya🇯🇵 · S. Hashimoto🇯🇵 · T. Kaneko🇯🇵 · J. Noaki🇯🇵 · T. Onogi🇯🇵

    We calculate the form factors of the $K\to \pi l\nu$ semileptonic decays in three-flavor lattice QCD, and study their chiral behavior as a function of the momentum transfer and the Nambu-Goldstone boson masses. Chiral symmetry is exactly preserved by using the overlap quark action, which enables us to directly compare the lattice data with chiral perturbation theory (ChPT). We generate gauge ensembles at a lattice spacing of 0.11fm with four pion masses covering 290-540 MeV and a strange quark mass m_s close to its physical value. By using the all-to-all quark propagator, we calculate the vector and scalar form factors with high precision. Their dependence on m_s and the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields. We compare the results for the semileptonic form factors with ChPT at next-to-next-to leading order in detail. While many low-energy constants appear at this order, we make use of our data of the light meson electromagnetic form factors in order to control the chiral extrapolation. We determine the normalization of the form factors as f_+(0) = 0.9636(36)(+57/-35), and observe reasonable agreement of their shape with experiment.

    ↳ hep-lathep-phPRD(2017)·24 citations
28. 28*

    Coherent J/$\psi$ photoproduction in hadronic heavy-ion collisions

    W. Zha🇨🇳 · S.R. Klein🇺🇸 · R. Ma🇺🇸 · L. Ruan🇺🇸 · T. Todoroki🇺🇸 · Z. Tang🇨🇳 · Z. Xu🇨🇳 · C. Yang🇨🇳 · Q. Yang🇨🇳 · S. Yang🇺🇸

    A significant excess of J/$\psi$ yield at very low transverse momentum ($p_T<0.3$ GeV/c) was observed by the ALICE and STAR collaborations in peripheral A+A collisions, which points to evidence of coherent photoproduction of J/$\psi$ in violent hadronic interactions. Theoretically, the photoproduction of J$/\psi$ in hadronic collisions raises questions about how spectator and non-spectator nucleons participate in the coherent reaction. For the first time, we argue that the strong interactions in the overlapping region of incoming nuclei may disturb the coherent production, leaving room for different coupling assumptions. Furthermore, first considerations of the destructive interference between photoproduction on ions moving in opposite directions in hadronic heavy-ion collisions are included. This letter presents calculations of J$/\psi$ production from coherent photon-nucleus ($\gamma +A\to \text{J}/\psi +A$) interactions in hadronic A+A collisions at RHIC and LHC energies with both nucleus and spectator coupling hypotheses. The coherent J/$\psi$ yield as a function of centrality and differential distributions as a function of transverse momentum, azimuthal angle and rapidity in different centrality bins are shown and found to be significantly different for different coupling scenarios, calling for future experimental measurements.

    ↳ nucl-thhep-phnucl-exPRC(2018)·80 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.