Thu·Jun 7, 2018Thursday·June 7, 2018

1. 01*

   When Freeze-out Precedes Freeze-in: Sub-TeV Fermion Triplet Dark Matter with Radiative Neutrino Mass

   Anirban Biswas🇮🇳 · Debasish Borah🇮🇳 · Dibyendu Nanda🇮🇳

   We propose a minimal predictive scenario for dark matter and radiative neutrino mass where the relic abundance of dark matter is generated from a hybrid setup comprising of both thermal freeze-out as well as non-thermal freeze-in mechanisms. Considering three copies of fermion triplets and one scalar doublet, odd under an unbroken ${\mathbb{Z}}_2$ symmetry, to be responsible for radiative origin of neutrino mass, we consider the lightest fermion triplet as a dark matter candidate which remains under-abundant in the sub-TeV regime from usual thermal freeze-out. Late decay of the ${\mathbb{Z}}_2$-odd scalar doublet into dark matter serves as the non-thermal (freeze-in) contribution which not only fills the thermal dark matter deficit, but also constrains the mother particle's parameter space so that the correct relic abundance of dark matter is generated. Apart from showing interesting differences from the purely freeze-out and purely freeze-in dark matter scenarios, the model remains testable through disappearing charge track signatures at colliders, observable direct and indirect detection rates for dark matter and prediction of almost vanishing lightest neutrino mass.

   hep-phastro-ph.COJCAP(2018)·16 citations
2. 02*

   Global analysis of charge exchange meson production at high energies

   JPAC Collaboration: J. Nys🇧🇪 · A. N. Hiller Blin🇩🇪 · V. Mathieu🇺🇸 · C. Fernández-Ramírez🇲🇽 · A. Jackura🇺🇸 · A. Pilloni🇺🇸 · J. Ryckebusch🇧🇪 · A. P. Szczepaniak🇺🇸 · G. Fox🇺🇸

   Many experiments that are conducted to study the hadron spectrum rely on peripheral resonance production. Hereby, the rapidity gap allows the process to be viewed as an independent fragmen- tation of the beam and the target, with the beam fragmentation dominated by production and decays of meson resonances. We test this separation by determining the kinematic regimes that are dominated by factorizable contributions, indicating the most favorable regions to perform this kind of experiments. In doing so, we use a Regge model to analyze the available world data of charge exchange meson production with beam momentum above 5 GeV in the laboratory frame, that are not dominated by either pion or Pomeron exchanges. We determine the Regge residues and point out the kinematic regimes which are dominated by factorizable contributions.

   hep-phPRD(2018)·16 citations
3. 03*

   Classical Nonrelativistic Effective Field Theories for a Real Scalar Field

   Eric Braaten🇺🇸 · Abhishek Mohapatra🇺🇸 · Hong Zhang🇩🇪

   A classical nonrelativistic effective field theory for a real Lorentz-scalar field $\varphi$ is most conveniently formulated in terms of a complex scalar field $\psi$. There have been two derivations of effective Lagrangians for the complex field $\psi$ in which terms in the effective potential were determined to order $({\psi }^{\ast }\psi {)}^4$. We point out an error in each of the effective Lagrangians. After correcting the errors, we demonstrate the equivalence of the two effective Lagrangians by verifying that they both reproduce $T$-matrix elements of the relativistic real scalar field theory and by also constructing a redefinition of the complex field $\psi$ that transforms terms in one effective Lagrangian into the corresponding terms of the other.

   hep-phPRD(2018)·38 citations
4. 04*

   Heavy Flavor Azimuthal Correlations in Cold Nuclear Matter

   R. Vogt🇺🇸

   Background: It has been proposed that the azimuthal distributions of heavy flavor quark-antiquark pairs may be modified in the medium of a heavy-ion collision. Purpose: This work tests this proposition through next-to-leading order (NLO) calculations of the azimuthal distribution, $d\sigma /d\varphi$, including transverse momentum broadening, employing $<k_T^2>$ and fragmentation in exclusive $Q\bar{Q}$ pair production. While these studies were done for $p+p$, $p+\bar{p}$ and $p+$Pb collisions, understanding azimuthal angle correlations between heavy quarks in these smaller, colder systems is important for their interpretation in heavy-ion collisions. Methods: First, single inclusive $p_T$ distributions calculated with the exclusive HVQMNR code are compared to those calculated in the fixed-order next-to-leading logarithm approach. Next the azimuthal distributions are calculated and sensitivities to $<k_T^2>$, $p_T$ cut, and rapidity are studied at $\sqrt{s}=7$ TeV. Finally, calculations are compared to $Q\bar{Q}$ data in elementary $p+p$ and $p+\bar{p}$ collisions at $\sqrt{s}=7$ TeV and 1.96 TeV as well as to the nuclear modification factor $R_{p\mathrm{Pb}}(p_T)$ in $p+$Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV measured by ALICE. Results: The low $p_T$ ($p_T<10$ GeV) azimuthal distributions are very sensitive to the $k_T$ broadening and rather insensitive to the fragmentation function. The NLO contributions can result in an enhancement at $\varphi \sim 0$ absent any other effects. Agreement with the data was found to be good. Conclusions: The NLO calculations, assuming collinear factorization and introducing $k_T$ broadening, result in significant modifications of the azimuthal distribution at low $p_T$ which must be taken into account in calculations of these distributions in heavy-ion collisions.

   hep-phnucl-thPRC(2018)·27 citations
5. 05*

   $K^0\Lambda$ photoproduction off the neutron with nucleon resonances

   Sang-Ho Kim🇰🇷 · Hyun-Chul Kim🇰🇷

   We investigate kaon photoproduction off the neutron target, i.e., $\gamma n\to K^0\Lambda$, focusing on the role of nucleon resonances given in the Review of Particle Data Group in the range of $\sqrt{s}\approx 1600-2200$ MeV. We employ an effective Lagrangian method and a Regge approach. The strong couplings of nucleon resonances with $K\Lambda$ vertices are constrained by quark model predictions. The numerical results of the total and differential cross sections are found to be in qualitative agreement with the recent CLAS and FOREST experimental data. We discuss the effects of the narrow nucleon resonance $N(1685,1/2^{+})$ on both the total and differential cross sections near the threshold energy. In addition, we present the results of the beam asymmetry as a prediction.

   hep-phhep-exnucl-exnucl-thPLB(2018)·14 citations
6. 06*

   Single production of the excited electrons at the future FCC-based lepton-hadron colliders

   Abdullatif Caliskan🇹🇷 · Seyit Okan Kara🇹🇷

   We study composite electron production at the FCC-based three electron-proton colliders with the center-of-mass energies of $3.46$, $10$ and $31.6$ TeV. For the signal process of $ep\to e^{\star }X\to e\gamma X$ , the production cross-sections and decay widhts of the excited electrons have been calculated. The differences of some kinematical quantities of the final state particles between the signal and background have been analyzed. For this purpose, transverse momentum and pseudorapidity distributions of electron and photon have been obtained and the kinematical cuts for discovery of the excited electrons have been assigned. We have finally determined the mass limits of excited electrons for observation and discovery by applying these cuts. It is shown that the mass limit for discovery obtained from the collider with $\sqrt{s}=31.6$ TeV (called PWFA-LC$\otimes$FCC) is $22.3$ TeV for the integrated luminosity $L_{int}=10$ $f{b}^{-1}$.

   hep-phInt.J.Mod.Phys.A(2018)·11 citations
7. 07*

   Study of $B_c$$\to$$J/\psi V$ and $B_c^{\ast }$$\to$${\eta }_{c}V$ decays within the QCD factorization

   Qin Chang🇨🇳 · Li-Li Chen🇨🇳 · Shuai Xu🇨🇳

   In this paper, we study the non-leptonic $B_c\to J/\psi V$ and $B_c^{\ast }\to {\eta }_{c}V$~$(V=\rho ,K^{\ast })$ weak decays in the framework of QCD factorization. In the evaluation, the form factors are calculated by using the Bauer-Stech-Wirbel model and the light-front quark model, respectively. Besides the longitudinal amplitude, the power-suppressed transverse contributions are also evaluated at next-to-leading order. The predictions for the observables of $B_c\to J/\psi V$ and $B_c^{\ast }\to {\eta }_{c}V$ decays are presented. We find that the NLO QCD contribution presents about $8\%$ correction to the branching ratios, and the longitudinal polarization fractions of these decays are at the level of $(80\sim 90)\%$. In addition, we suggest direct measurements on some useful ratios, $R_{K^{\ast }/\rho }^{(\lambda =0)}$ and ${\tilde{R}}_{K^{\ast }/\rho }^{(\lambda =0)}$, which are very suitable for test the consistence between theoretical prediction and data because their theoretical uncertainties can be well-controlled.

   hep-phhep-exJ.Phys.G(2018)·14 citations
8. 08*

   Thermodynamics of a gas of hadrons with attractive and repulsive interaction within S-matrix formalism

   Ashutosh Dash🇮🇳 · Subhasis Samanta🇮🇳 · Bedangadas Mohanty🇮🇳

   We report the effect of including repulsive interactions on various thermodynamic observables calculated using a S-matrix based Hadron Resonance Gas (HRG) model to already available corresponding results with only attractive interactions [A. Dash, S. Samanta, and B. Mohanty, Phys. Rev. C 97, 055208 (2018)]. The attractive part of the interaction is calculated by parameterizing the two body phase shifts using K-matrix formalism while the repulsive part is included by fitting to the experimental phase shifts which carry the information about the nature of the interaction. We find that the bulk thermodynamic variables for a gas of hadrons such as energy density, pressure, entropy density, speed of sound and specific heat are suppressed by the inclusion of repulsive interactions and are more pronounced for second and higher order correlations and fluctuations, particularly for the observables ${\chi }_Q^2$, ${\chi }_B^2-{\chi }_B^4$ and $C_{BS}$ in the present model. We find a good agreement between lattice QCD simulations and the present model for $C_{BS}$. We have also computed two leading order Fourier coefficients of the imaginary part of the first order baryonic susceptibility at imaginary baryon chemical potential within this model and compared them with the corresponding results from lattice. Additionally, assuming that the value of interacting pressure versus temperature for a gas of hadrons calculated in S-matrix formalism is same as that from a van der Waals HRG (VDWHRG) model, we have quantified the attractive and repulsive interactions in our model in terms of attractive and repulsive parameters used in the VDWHRG model. The values of parameters thus obtained are $a=1.54\pm 0.064$ GeV ${\text{fm}}^3$ and $r=0.81\pm 0.014$ fm.

   hep-phnucl-thPRC(2019)·31 citations
9. 09*

   Heavy baryon decay widths in the large $N_c$ limit in chiral theory

   Michal Praszalowicz🇵🇱

   We propose large $N_c$ generalizations for the "diquark" representations of SU(3)${}_{\mathrm{flav}}$ relevant for positive parity heavy baryons, including putative exotic states. Next, within the framework of the Chiral Quark Soliton Model, we calculate heavy baryon masses and decay widths. We show that in the limit of $N_c\to \infty$ {\em all} decay widths vanish, including the widths of exotica. This result is in fact more general than the model itself, as it relies only on the underlying symmetries: i.e. SU(3)${}_{\mathrm{flav}}$ and hedgehog symmetry. Furthermore, using explicit model formulae for the decay constants in the non-realtivistic limit, we show that there is a hierarchy of the decay couplings, which may explain observed pattern of experimental widths.

   hep-phEPJC(2018)·6 citations
10. 10*

    Thermodynamics of strange baryon system from coupled-channel analysis and missing states

    César Fernández-Ramírez🇲🇽 · Pok Man Lo🇵🇱 · Peter Petreczky🇺🇸

    We study the thermodynamics of the strange baryon system using an S-matrix formulation of statistical mechanics. For this purpose, we employ an existing coupled-channel study involving $\bar{K}N$, $\pi \Lambda$, and $\pi \Sigma$ interactions in the $S=-1$ sector. A novel method is proposed to extract an effective phase shift due to the interaction, which can subsequently be used to compute various thermal observables via a relativistic virial expansion. As an application of the calculation scheme, we compute the correlation of the net baryon number with strangeness (${\chi }_{BS}$) for an interacting hadron gas. We show that the S-matrix approach, which entails a consistent treatment of resonances and naturally incorporates the additional hyperon states which are not listed by the Particle Data Group, leads to an improved description of the lattice data over the Hadron Resonance Gas model.

    hep-phhep-latPRC(2018)·31 citations
11. 11*

    Quark and Lepton Mixing Patterns from a Common Discrete Flavor Symmetry with Generalized CP

    Jun-Nan Lu🇨🇳 · Gui-Jun Ding🇨🇳

    We have studied two approaches to predict quark and lepton mixing patterns from the same flavor symmetry group in combination with CP symmetry. The first approach is based on the residual symmetry $Z_2$ in the charged lepton sector and $Z_2\times CP$ in the neutrino sector. All lepton mixing angles and CP violation phases depend on three real parameters ${\theta }_l$, ${\delta }_l$ and ${\theta }_{\nu }$. This approach is extended to the quark sector, the up and down quark mass matrices are assumed to be invariant under a $Z_2$ subgroup and $Z_2\times CP$. The necessary and sufficient conditions for the equivalence of two mixing patterns are derived. The second approach has an abelian subgroup and a single CP transformation as residual symmetries of the charged lepton and neutrino sectors respectively. The lepton mixing would be determined up to a real orthogonal matrix multiplied from the right hand side. Analogously we assume that a single CP transformation is preserved by the down (or up) quark mass matrix, and the residual symmetry of the up (or down) quark sector is be an abelian subgroup. As an example, we analyze the possible mixing patterns which can be obtained from the breaking of $\Delta (6n^2)$ and CP symmetries. We find $\Delta (294)$ combined with CP is the smallest flavor group which can give a good fit to the experimental data of quark and lepton mixing in both approaches.

    hep-phPRD(2018)·33 citations
12. 12*

    Simultaneous interpretation of $K$ and $B$ anomalies in terms of chiral-flavorful vectors

    Shinya Matsuzaki🇨🇳 · Kenji Nishiwaki🇰🇷 · Kei Yamamoto🇯🇵

    We address the presently reported significant flavor anomalies in the Kaon and $B$ meson systems such as the CP violating Kaon decay (${ϵ}^{\prime }/ϵ$) and lepton-flavor universality violation in $B$ meson decays ($R_{K^{(\ast )}},R_{D^{(\ast )}}$), by proposing flavorful and chiral vector bosons as the new physics constitution at around TeV scale. The chiral-flavorful vectors (CFVs) are introduced as a 63-plet of the global $SU(8)$ symmetry, identified as the one-family symmetry for left-handed quarks and leptons in the standard model (SM) forming the 8-dimensional vector. Thus the CFVs include massive gluons, vector leptoquarks, and $W^{\prime },Z^{\prime }$-type bosons, which are allowed to have flavorful couplings with left-handed quarks and leptons, and flavor-universal couplings to right-handed ones, where the latter arises from mixing with the SM gauge bosons. The flavor texture is assumed to possess a "minimal" structure to be consistent with the current flavor measurements on the $K$ and $B$ systems. Among the presently reported significant flavor anomalies in the Kaon and $B$ meson systems (${ϵ}^{\prime }/ϵ$, $R_{K^{(\ast )}},R_{D^{(\ast )}}$), the first two ${ϵ}^{\prime }/ϵ$ and $R_{K^{(\ast )}}$ anomalies can simultaneously be interpreted by the presence of CFVs, the $R_{D^{(\ast )}}$ anomaly is predicted not to survive, due to the approximate $SU(8)$ flavor symmetry. Remarkably, we find that as long as both of the ${ϵ}^{\prime }/ϵ$ and $R_{K^{(\ast )}}$ anomalies persist beyond the SM, the CFVs predict the enhanced $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ and $K_L\to {\pi }^0\nu \bar{\nu }$ decay rates compared to the SM values, which will readily be explored by the NA62 and KOTO experiments, and they will also be explored in new resonance searches at the Large Hadron Collider.

    hep-phhep-exJHEP(2018)·42 citations
13. 13*

    Model Discrimination in Gravitational Wave spectra from Dark Phase Transitions

    Djuna Croon🇺🇸 · Veronica Sanz🇬🇧 · Graham White🇨🇦

    In anticipation of upcoming gravitational wave experiments, we provide a comprehensive overview of the spectra predicted by phase transitions triggered by states from a large variety of dark sector models. Such spectra are functions of the quantum numbers and (self-) couplings of the scalar that triggers the dark phase transition. We classify dark sectors that give rise to a first order phase transition and perform a numerical scan over the thermal parameter space. We then characterize scenarios in which a measurement of a new source of gravitational waves could allow us to discriminate between models with differing particle content.

    hep-phastro-ph.COJHEP(2018)·165 citations
14. 14*

    ALPs at FASER: The LHC as a Photon Beam Dump

    Jonathan L. Feng🇺🇸 · Iftah Galon🇺🇸 · Felix Kling🇺🇸 · Sebastian Trojanowski🇺🇸

    The goal of FASER, ForwArd Search ExpeRiment at the LHC, is to discover light, weakly-interacting particles with a small and inexpensive detector placed in the far-forward region of ATLAS or CMS. A promising location in an unused service tunnel 480 m downstream of the ATLAS interaction point (IP) has been identified. Previous studies have found that FASER has significant discovery potential for new particles produced at the IP, including dark photons, dark Higgs bosons, and heavy neutral leptons. In this study, we explore a qualitatively different, `beam dump' capability of FASER, in which the new particles are produced not at the IP, but through collisions in detector elements further downstream. In particular, we consider the discovery prospects for axion-like particles (ALPs) that couple to the standard model through the $a\gamma \gamma$ interaction. TeV-scale photons produced at the IP collide with the TAN neutral particle absorber 130 m downstream, producing ALPs through the Primakoff process, and the ALPs then decay to two photons in FASER. We show that FASER can discover ALPs with masses $m_a\sim 30-400\text{MeV}$ and couplings $g_{a\gamma \gamma }\sim 10^{-6}-10^{-3}{\text{GeV}}^{-1}$, and we discuss the ALP signal characteristics and detector requirements.

    hep-phPRD(2018)·158 citations
15. 15*

    Learning New Physics from a Machine

    Raffaele Tito D'Agnolo🇺🇸 · Andrea Wulzer🇨🇭

    We propose using neural networks to detect data departures from a given reference model, with no prior bias on the nature of the new physics responsible for the discrepancy. The virtues of neural networks as unbiased function approximants make them particularly suited for this task. An algorithm that implements this idea is constructed, as a straightforward application of the likelihood-ratio hypothesis test. The algorithm compares observations with an auxiliary set of reference-distributed events, possibly obtained with a Monte Carlo event generator. It returns a p-value, which measures the compatibility of the reference model with the data. It also identifies the most discrepant phase-space region of the data set, to be selected for further investigation. The most interesting potential applications are model-independent new physics searches, although our approach could also be used to compare the theoretical predictions of different Monte Carlo event generators, or for data validation algorithms. In this work we study the performance of our algorithm on a few simple examples. The results confirm the model-independence of the approach, namely that it displays good sensitivity to a variety of putative signals. Furthermore, we show that the reach does not depend much on whether a favorable signal region is selected based on prior expectations. We identify directions for improvement towards applications to real experimental data sets.

    hep-phhep-exphysics.comp-phPRD(2019)·201 citations
16. 16*

    Post-inflationary thermal histories and the refractive index of relic gravitons

    Massimo Giovannini🇨🇭

    We investigate the impact of the post-inflationary thermal histories on the cosmic graviton spectrum caused by the inflationary variation of their refractive index. Depending on the frequency band, the spectral energy distribution can be mildly red, blue or even violet. Wide portions of the parameter space lead to potentially relevant signals both in the audio range (probed by the advanced generation of terrestrial interferometers) and in the mHz band (where space-borne detectors could be operational within the incoming score year). The description of the refractive index in conformally related frames is clarified.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·16 citations
17. 17*

    Superconducting vortex in a deconstructed holographic model

    Zainul Abidin🇮🇩 · Herry J. Kwee🇮🇩 · Jong Anly Tan🇰🇷

    A deconstructed holographic model for an $s$-wave superconductor in $2+1$ dimensions has been proposed in the literature. Here, we consider solutions in the presence of perpendicular magnetic fields, where vortex formed. We calculate the expectation value of the Cooper pair condensate as a function of radial distance from the center of the vortex for different numbers of lattice points.

    ↳ hep-thhep-ph0 citations
18. 18*

    Fast Radio Bursts and the Axion Quark Nugget Dark Matter Model

    Ludovic van Waerbeke🇨🇦 · Ariel Zhitnitsky🇨🇦

    We explore the possibility that the Fast Radio Bursts (FRBs) are powered by magnetic reconnection in magnetars, triggered by Axion Quark Nugget (AQN) dark matter. In this model, the magnetic reconnection is ignited by the shock wave which develops when the nuggets' Mach number $M\gg 1$. These shock waves generate very strong and very short impulses expressed in terms of pressure $\Delta p/p\sim M^2$ and temperature $\Delta T/T\sim M^2$ in the vicinity of (would be) magnetic reconnection area. We find that the proposed mechanism produces a coherent emission which is consistent with current data, in particular the FRB energy requirements, the observed energy distribution, the frequency range and the burst duration. Our model allows us to propose additional tests which future data will be able to challenge.

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2019)·27 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.