Tue·Apr 23, 2019Tuesday·April 23, 2019

1. 01*

   Global fit to $b\to c\tau \nu$ transitions

   Clara Murgui🇪🇸 · Ana Peñuelas🇪🇸 · Martin Jung🇩🇪 · Antonio Pich🇪🇸

   We perform a general model-independent analysis of $b\to c\tau {\bar{\nu }}_{\tau }$ transitions, including measurements of ${\mathcal{R}}_D$, ${\mathcal{R}}_{D^{\ast }}$, their $q^2$ differential distributions, the recently measured longitudinal $D^{\ast }$ polarization $F_L^{D^{\ast }}$, and constraints from the $B_c\to \tau {\bar{\nu }}_{\tau }$ lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected $b\to c\tau {\bar{\nu }}_{\tau }$ observables, such as the baryonic transition ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$, the ratio ${\mathcal{R}}_{J/\psi }$, the forward-backward asymmetries ${\mathcal{A}}_{\text{FB}}^{D^{(\ast )}}$, the $\tau$ polarization asymmetries ${\mathcal{P}}_{\tau }^{D^{(\ast )}}$, and the longitudinal $D^{\ast }$ polarization fraction $F_L^{D^{\ast }}$. The latter shows presently a slight tension with any new-physics model, such that an improved measurement could have an important impact. We also discuss the potential change due the very recently announced preliminary ${\mathcal{R}}_{D^{(\ast )}}$ measurement by the Belle collaboration.

   hep-phJHEP(2019)·184 citations
2. 02*

   Multi-jet merging in a variable flavor number scheme

   Stefan Höche🇺🇸 · Johannes Krause🇩🇪 · Frank Siegert🇩🇪

   We propose a novel technique for the combination of multi-jet merged simulations in the five-flavor scheme with calculations for the production of b-quark associated final states in the four-flavor scheme. We show the equivalence of our algorithm to the FONLL method at the fixed-order and logarithmic accuracy inherent to the matrix-element and parton-shower simulation employed in the multi-jet merging. As a first application we discuss Zbb production at the Large Hadron Collider.

   hep-phPRD(2019)·27 citations
3. 03*

   Phenomenology of Higgs bosons in inverse seesaw model with Type-X two Higgs doublet at the LHC

   Priyotosh Bandyopadhyay🇮🇳 · Eung Jin Chun🇰🇷 · Rusa Mandal🇪🇸

   Type-X two Higgs doublet model is known to explain the muon $g-2$ anomaly with a relatively light charged Higgs boson at large $\tan \beta$. The light charged Higgs boson has been searched in the main $\tau \nu$ mode at the colliders. Invoking a scenario of inverse seesaw as the origin of neutrino masses and mixing, the charged Higgs boson can decay additionally to right-handed neutrinos which leads to interesting phenomenology. Considering generic lepton flavour violating signatures at the final states, a $5\sigma$ discovery can be achieved with the early data of LHC, at 14 TeV, for relatively large inverse seesaw Yukawa coupling $Y_N$. The very light pseudoscalar and charged Higgs boson mass reconstruction are performed using the new modes and the results look promising. The inverse seesaw Yukawa coupling is shown to be probed down to $Y_N\sim 0.2$ at HL LHC with 3000 fb${}^{-1}$.

   hep-phJHEP(2019)·8 citations
4. 04*

   Interference effects for the top quark decays $t\to b+W^{+}/H^{+}(\to {\tau }^{+}{\nu }_{\tau })$

   S. Mohammad Moosavi Nejad🇮🇷 · S. Abbaspour🇮🇷 · R. Farashahian🇮🇷

   Applying the narrow-width approximation (NWA), we first review the NLO QCD predictions for the total decay rate of top quark considering two unstable intermediate particles: the $W^{+}$-boson in the standard model (SM) of particle physics and the charged Higgs boson $H^{+}$ in the generic type-I and II two-Higgs-doublet models, i.e. $t\to b+W^{+}/H^{+}(\to {\tau }^{+}{\nu }_{\tau })$. We then estimate the errors arised from this approximation at leading-order perturbation theory. Finally, we shall investigate the interference effects in the factorization of production and decay parts of intermediate particles. We will show that for nearly mass-degenerate states ($m_{H^{+}}\approx m_{W^{+}}$), the correction due to the interference effect is considerable.

   hep-phPRD(2019)·7 citations
5. 05*

   Neural Network Study of Hidden-Charm Pentaquark Resonances

   Halil Mutuk🇹🇷

   Very recently, LHCb experiment announced the observation of hidden-charm pentaquark states $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$ near the ${\Sigma }_c\bar{D}$ and ${\Sigma }_c{\bar{D}}^{\ast }$ thresholds, respectively. In this present work, we studied thesepentaquarks in the framework of the nonrelativistic quark model with four types of potential. We solved 5-body Schrödinger equation by using artificial neural network method and made predictions of parities for these states which are not determined in the experiment yet. The mass of another possible pentaquark state near the ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ with $J^P=5/2^{-}$ is also calculated.

   hep-phCPC(2019)·40 citations
6. 06*

   Direct detections of Majorana dark matter in vector portal

   Wei Chao🇨🇳

   In this paper we investigate the direct detections of Majorana dark matter (MDM) in vector portal. Taking into account that the tree-level scattering cross sections in these models are either dark matter velocity suppressed or spin-dependent, we calculate radiative corrections to the spin-independent cross section in effective field theory approach. Wilson coefficients of effective MDM-quark interactions are calculated at the one-loop level, and the Wilson coefficient of the effective MDM-gluon interaction is derived at the two-loop level. Numerical results show that current constraints can rule out a narrow mass range of MDM when tree-level contributions are considered, and the spin-independent cross section from radiative corrections is reachable by the current direct detection technique for light MDM.

   hep-phJHEP(2019)·21 citations
7. 07*

   Capture of Leptophilic Dark Matter in Neutron Stars

   Nicole F. Bell🇦🇺 · Giorgio Busoni🇩🇪 · Sandra Robles🇦🇺

   Dark matter particles will be captured in neutron stars if they undergo scattering interactions with nucleons or leptons. These collisions transfer the dark matter kinetic energy to the star, resulting in appreciable heating that is potentially observable by forthcoming infrared telescopes. While previous work considered scattering only on nucleons, neutron stars contain small abundances of other particle species, including electrons and muons. We perform a detailed analysis of the neutron star kinetic heating constraints on leptophilic dark matter. We also estimate the size of loop induced couplings to quarks, arising from the exchange of photons and Z bosons. Despite having relatively small lepton abundances, we find that an observation of an old, cold, neutron star would provide very strong limits on dark matter interactions with leptons, with the greatest reach arising from scattering off muons. The projected sensitivity is orders of magnitude more powerful than current dark matter-electron scattering bounds from terrestrial direct detection experiments.

   hep-phastro-ph.COastro-ph.HEJCAP(2019)·135 citations
8. 08*

   NNLO charmed-meson fragmentation functions and their uncertainties in the presence of meson mass corrections

   Maral Salajegheh🇮🇷 · S. Mohammad Moosavi Nejad🇮🇷 · Maryam Soleymaninia🇮🇷 · Hamzeh Khanpour🇮🇷 · S. Atashbar Tehrani🇮🇷

   The main aim of this paper is to present new sets of non-perturbative fragmentation functions (FFs) for $D^0$ and $D^{+}$ mesons at next-to-leading (NLO) and, for the first time, at next-to-next-to-leading order (NNLO) in the $\overline{\mathrm{MS}}$ factorization scheme with five massless quark flavors. This new determination of FFs is based on the QCD fit to the {\tt OPAL} experimental data for hadron production in the electron-positron single-inclusive annihilation (SIA). We discuss in detail the novel aspects of the methodology used in our analysis and the validity of obtained FFs by comparing with previous works in literature which have been carried out up to NLO accuracy. We will also incorporate the effect of charmed meson mass corrections into our QCD analysis and discuss the improvements upon inclusion of these effects. The uncertainties in the extracted FFs as well as in the corresponding observables are estimated using the "Hessian" approach. For a typical application, we use our new FFs to make theoretical predictions for the energy distributions of charmed mesons inclusively produced through the decay of unpolarized top quarks, to be measured at the CERN LHC. As a result of this analysis, suggestions are discussed for possible future studies on the current topic to consider any theory improvements and other available experimental observables.

   hep-phhep-exEPJC(2019)·35 citations
9. 09*

   SU(3) Polyakov Linear-Sigma Model With Finite Isospin Asymmetry: QCD Phase Diagram

   Abdel Nasser Tawfik (Nile U., ECTP and WLCAPP, Cairo)🇪🇬 · Abdel Magied Diab (MUTI and WLCAPP, Cairo)🇪🇬 · M.T. Ghoneim🇪🇬 · H. Anwer (Cairo U.)🇪🇬

   The SU($3$) Polyakov linear-sigma model (PLSM) in mean-field approximation is utilized in analyzing the chiral condensates ${\sigma }_u$, ${\sigma }_d$, ${\sigma }_s$ and the deconfinement order parameters $\varphi$, $\bar{\varphi }$, at finite isospin asymmetry. The bulk thermodynamics including pressure density, interaction measure, susceptibility, and second-order correlations with baryon, strange and electric charge quantum numbers are studied in thermal and dense medium. The PLSM results are confronted to the available lattice QCD calculations. The excellent agreement obtained strengthens the reliability of fixing the PLSM parameters and therefore supports further predictions even beyond the scope of the lattice QCD numerical applicability. From the QCD phase structure at finite isospin chemical potential (${\mu }_I$), a novel expression for the explicit symmetry breaking term $h_3$ is introduced, we find that the pseudo-critical temperatures decrease with the increase in ${\mu }_I$. We conclude that the QCD phase structure in ($T_{\chi }$-${\mu }_I$) plane seems to extend the one in ($T_{\chi }$-${\mu }_B$) plane.

   hep-phInt.J.Mod.Phys.A(2019)·22 citations
10. 10*

    Hidden-charm pentaquarks and $P_c$ states

    Xin-Zhen Weng🇨🇳 · Xiao-Lin Chen🇨🇳 · Wei-Zhen Deng🇨🇳 · Shi-Lin Zhu🇨🇳

    Recently, the LHCb Collaboration reported three $P_c$ states in the $J/\psi p$ channel. We systematically study the mass spectrum of the hidden charm pentaquark in the framework of an extended chromomagnetic model. For the $nnnc\bar{c}$ pentaquark with $I=1/2$, we find that (i) the lowest state is $P_c(4327.0,1/2,1/2^{-})$ [We use $P_c(m,I,J^P)$ to denote the $nnnc\bar{c}$ pentaquark], which corresponds to the $P_c(4312)$. Its dominant decay mode is ${\Lambda }_c{\bar{D}}^{\ast }$. (ii) We find two states in the vicinity of $P_c(4380)$. The first one is $P_c(4367.4,1/2,3/2^{-})$ and decays dominantly to $NJ/\psi$ and ${\Lambda }_c{\bar{D}}^{\ast }$. The other one is $P_c(4372.4,1/2,1/2^{-})$. Its dominant decay mode is ${\Lambda }_c\bar{D}$, and its partial decay width of $N{\eta }_c$ channel is comparable to that of $NJ/\psi$. (iii) In higher mass region, we find $P_c(4476.3,1/2,3/2^{-})$ and $P_c(4480.9,1/2,1/2^{-})$, which correspond to $P_c(4440)$ and $P_c(4457)$. In the open charm channels, both of them decay dominantly to the ${\Lambda }_c{\bar{D}}^{\ast }$. (iv) We predict two states above $4.5\text{GeV}$, namely $P_c(4524.5,1/2,3/2^{-})$ and $P_c(4546.0,1/2,5/2^{-})$. The masses of the $nnnc\bar{c}$ state with $I=3/2$ are all over $4.6\text{GeV}$. Moreover, we use the model to explore the $nnsc\bar{c}$, $ssnc\bar{c}$ and $sssc\bar{c}$ pentaquark states.

    hep-phhep-exhep-latnucl-thPRD(2019)·119 citations
11. 11*

    Determining the space-time structure of bottom-quark couplings to spin-zero particles

    Tathagata Ghosh🇺🇸 · Rohini Godbole🇮🇳 · Xerxes Tata🇺🇸

    We present a general argument that highlights the difficulty of determining the space-time structure of the renormalizable bottom quark Yukawa interactions of the Standard Model Higgs boson, or for that matter of any hypothetical spin-zero particle, at high energy colliders. The essence of the argument is that, it is always possible, by chiral rotations, to transform between scalar and pseudoscalar Yukawa interactions without affecting the interactions of bottom quarks with SM gauge bosons. Since these rotations affect only the $b$-quark mass terms in the Standard Model Lagrangian, any differences in observables for scalar versus pseudoscalar couplings vanish when $m_b\to 0$, and are strongly suppressed in high energy processes involving the heavy spin-zero particle where the $b$-quarks are typically relativistic. We show, however, that the energy dependence of, for instance, $e^{+}{e}^{-}\to b\bar{b}X$ (here $X$ denotes the spin-zero particle) close to the reaction threshold may serve to provide a distinction between the scalar versus pseudoscalar coupling at electron-positron colliders that are being proposed, provided that the $Xb\bar{b}$ coupling is sizeable. We also note that while various kinematic distributions for $t\bar{t}h$ are indeed sensitive to the space-time structure of the top Yukawa coupling, for a spin-0 particle $X$ of an arbitrary mass, the said sensitivity is lost if $m_X>>m_t$.

    hep-phhep-exPRD(2019)·11 citations
12. 12*

    The Scalar Hexaquark $uuddss$: a Candidate to Dark Matter?

    K. Azizi🇹🇷 · S. S. Agaev🇦🇿 · H. Sundu🇹🇷

    It is conventionally argued that Dark Matter (DM) has a non-baryonic nature, but if we assume that DM was frozen out before primordial nucleosynthesis and could not significantly impact primordial abundances this argument may be evaded. Then a hypothetical $SU(3)$ flavor-singlet, highly symmetric, deeply bound neutral scalar hexaquark $\mathrm{S}=uuddss$, which due to its features has escaped from experimental detection so far, may be considered as a candidate for a baryonic DM. In the present work we calculate the mass and coupling constant of the scalar six-quark particle $\mathrm{S}$ by means of the QCD sum rule method. Our predictions for its mass are $m_S=1180_{-26}^{+40}\mathrm{MeV}$ ($m_s=95\mathrm{MeV}$) and ${\tilde{m}}_S=1239_{-28}^{+42}\mathrm{MeV}$ ($m_s=128\mathrm{MeV}$). Although these values of mass would produce thermally the cosmological DM abundance, existence of this state may contradict to stability of the oxygen nuclei, which requires further thorough analysis.

    hep-phastro-ph.GAhep-exhep-latJ.Phys.G(2020)·34 citations
13. 13*

    Nuclear gluons at RHIC in a multi-observable approach

    Ilkka Helenius🇫🇮 · John Lajoie🇺🇸 · Joseph D. Osborn🇺🇸 · Petja Paakkinen🇫🇮 · Hannu Paukkunen🇫🇮

    We explore the possibility of measuring nuclear gluon distributions at the Relativistic Heavy-Ion Collider (RHIC) with $\sqrt{s}=200\mathrm{GeV}$ proton-nucleus collisions. In addition to measurements at central rapidity, we consider also observables at forward rapidity, consistent with proposed upgrades to the experimental capabilities of STAR and sPHENIX. The processes we consider consist of Drell-Yan dilepton, dijet, and direct photon-jet production. The Drell-Yan process is found to be an efficient probe of gluons at small momentum fractions. In order to fully utilize the potential of Drell-Yan measurements we demonstrate how the overall normalization uncertainty present in the experimental data can be fixed using other experimental observables. An asset of the RHIC collider is its flexibility to run with different ion beams, and we outline how this ability could be taken advantage of to measure the $A$ dependence of gluon distributions for which the current constraints are scarce.

    hep-phhep-exnucl-exPRD(2019)·7 citations
14. 14*

    Freeze-in and Freeze-out of Dark Matter with Charged Long-lived Partners

    Sreemanti Chakraborti🇮🇳 · Victoria Martin🇬🇧 · Poulose Poulose🇮🇳

    We present a novel framework capable of addressing the dark matter problem through freeze-in and freeze-out mechanisms, separately or together, depending on the region of the parameter space considered. In the dark matter dynamics, the model features an interplay of thermal production along with sizeable contribution through feeble decay of associated dark fermionic partner, which finally freezes out to the right relic density for a wide range of masses and couplings. Apart from the fermionic dark matter candidate, the model introduces two charged partners, one fermionic and another scalar, which often have delayed decays leading to distinct characteristics of such long-lived particles (LLP) in the colliders like the LHC. Our analysis shows that within the present scenario, LLP of decay length that could be probed at the LHC experiments are compatible with dark matter masses ranging from a few GeV to close to a TeV, as opposed to the requirement of keV-MeV dark matter in simple FIMP scenarios with LLP. In addition, the model presents hitherto unexplored interesting possibilities in the LLP searches, like (i) LLP to LLP to SM cascade decays, which could be searched for within the LHC detectors and (ii) heavy neutral particle decaying within MATHUSLA with two jets and large missing energy. A supplementary aspect of the model is the presence of a heavy neutrino facilitating Type-I seesaw mechanism without disturbing the dark matter side.

    hep-phJCAP(2020)·12 citations
15. 15*

    Relativistic and spectator effects in leptogenesis with heavy sterile neutrinos

    Björn Garbrecht🇩🇪 · Philipp Klose🇧🇪 · Carlos Tamarit🇩🇪

    For leptogenesis with heavy sterile neutrinos above the electroweak scale, asymmetries produced at early times (in the relativistic regime) are relevant, if they are protected from washout. This can occur for weak washout or when the asymmetry is partly protected by being transferred to spectator fields. We thus study the relevance of relativistic effects for leptogenesis in a minimal seesaw model with two sterile neutrinos in the strongly hierarchical limit. Starting from first principles, we derive a set of momentum-averaged fluid equations to calculate the final $B-L$ asymmetry as a function of the washout strength and for different initial conditions at order one accuracy. For this, we take the leading fluid approximation for the relativistic $CP$-even and odd rates. Assuming that spectator fields remain in chemical equilibrium, we find that for weak washout, relativistic corrections lead to a sign flip and an enhancement of the asymmetry for a vanishing initial abundance of sterile neutrinos. As an example for the effect of partially equilibrated spectators, we consider bottom-Yukawa and weak-sphaleron interactions in leptogenesis driven by sterile neutrinos with masses $\gtrsim 5\times 10^{12}$ GeV. For a vanishing initial abundance of sterile neutrinos, this can give rise to another flip and an absolute enhancement of the final asymmetry in the strong washout regime by up to two orders of magnitude relative to the cases either without spectators or with fully equilibrated ones. These effects are less pronounced for thermal initial conditions for the sterile neutrinos. The $CP$-violating source in the relativistic regime at early times is important as it is proportional to the product of lepton-number violating and lepton-number conserving rates, and therefore less suppressed than an extrapolation of the nonrelativistic approximations may suggest.

    hep-phJHEP(2020)·33 citations
16. 16*

    Higgs production in bottom-quark fusion to third order in the strong coupling

    Claude Duhr🇨🇭 · Falko Dulat🇺🇸 · Bernhard Mistlberger🇺🇸

    We present the inclusive cross section at next-to-next-to-next-to-leading order (N${}^3$LO) in perturbative QCD for the production of a Higgs boson via bottom-quark fusion. We employ the five-flavour scheme, treating the bottom quark as a massless parton while retaining a non-vanishing Yukawa coupling to the Higgs boson. We find that the dependence of the hadronic cross section on the renormalisation and factorisation scales is substantially reduced. For judicious choices of the scales the perturbative expansion of the cross section shows a convergent behaviour. We present results for the N${}^3$LO cross section at various collider energies. In comparison to the cross section obtained from the Santander-matching of the four and five-flavour schemes we predict a slightly higher cross section, though the two predictions are consistent within theoretical uncertainties.

    hep-phPRL(2020)·121 citations
17. 17*

    Viable low-scale model with Universal and Inverse Seesaw Mechanisms

    A. E. Cárcamo Hernández🇨🇱 · Juan Marchant González🇨🇱 · U. J. Saldaña-Salazar🇩🇪

    We formulate a viable low-scale seesaw model, where the masses for the standard model (SM) charged fermions lighter than the top quark emerge from a universal seesaw mechanism mediated by charged vectorlike fermions. The small light active neutrino masses are produced from an inverse seesaw mechanism mediated by right-handed Majorana neutrinos. Our model is based on the $A_4$ family symmetry, supplemented by cyclic symmetries, whose spontaneous breaking produces the observed pattern of SM fermion masses and mixings. The model can accommodate the muon and electron anomalous magnetic dipole moments and predicts strongly suppressed $\mu \to e\gamma$ and $\tau \to \mu \gamma$ decay rates, but allows a $\tau \to e\gamma$ decay within the reach of the forthcoming experiments.

    hep-phPRD(2019)·35 citations
18. 18*

    Luminous Signals of Inelastic Dark Matter in Large Detectors

    Joshua Eby🇮🇱 · Patrick J. Fox🇺🇸 · Roni Harnik🇺🇸 · Graham D. Kribs🇺🇸

    We study luminous dark matter signals in models with inelastic scattering. Dark matter ${\chi }_1$ that scatters inelastically off elements in the Earth is kicked into an excited state ${\chi }_2$ that can subsequently decay into a monoenergetic photon inside a detector. The photon signal exhibits large sidereal-daily modulation due to the daily rotation of the Earth and anisotropies in the problem: the dark matter wind comes from the direction of Cygnus due to the Sun's motion relative to the galaxy, and the rock overburden is anisotropic, as is the dark matter scattering angle. This allows outstanding separation of signal from backgrounds. We investigate the sensitivity of two classes of large underground detectors to this modulating photon line signal: large liquid scintillator neutrino experiments, including Borexino and JUNO, and the proposed large gaseous scintillator directional detection experiment CYGNUS. Borexino's (JUNO's) sensitivity exceeds the bounds from xenon experiments on inelastic nuclear recoil for mass splittings $\delta \gtrsim 240(180)$ keV, and is the only probe of inelastic dark matter for $350\text{ keV}\lesssim \delta \lesssim 600\text{ keV}$. CYGNUS's sensitivity is at least comparable to xenon experiments with $\sim 10{\mathrm{m}}^3$ volume detector for $\delta \lesssim 150$ keV, and could be substantially better with larger volumes and improved background rejection. Such improvements lead to the unusual situation that the inelastic signal becomes the superior way to search for dark matter even if the elastic and inelastic scattering cross sections are comparable.

    hep-phJHEP(2019)·37 citations
19. 19*

    Deep-Learning Jets with Uncertainties and More

    Sven Bollweg🇩🇪 · Manuel Haussmann🇩🇪 · Gregor Kasieczka🇩🇪 · Michel Luchmann🇩🇪 · Tilman Plehn🇩🇪 · Jennifer Thompson🇩🇪

    Bayesian neural networks allow us to keep track of uncertainties, for example in top tagging, by learning a tagger output together with an error band. We illustrate the main features of Bayesian versions of established deep-learning taggers. We show how they capture statistical uncertainties from finite training samples, systematics related to the jet energy scale, and stability issues through pile-up. Altogether, Bayesian networks offer many new handles to understand and control deep learning at the LHC without introducing a visible prior effect and without compromising the network performance.

    hep-phSciPost Phys.(2020)·95 citations
20. 20*

    Fermion Mass Hierarchy and Phenomenology in the 5D Domain Wall Standard Model

    Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸 · Desmond Villalba🇺🇸

    We have recently proposed a setup of the "Domain-Wall Standard Model" in 5D spacetime, where all the Standard Model (SM) fields are localized in certain domains of the extra 5th dimension. Utilizing this setup, we attempt to solve the fermion mass hierarchy problem of the SM. The mass hierarchy can be naturally explained by suitably distributing the fermions in different positions along the extra dimension. Due to these different localization points, the effective 4D gauge couplings of Kaluza-Klein (KK) mode gauge bosons to the SM fermions become non-universal. As a result, our model is severely constrained by the Flavor Changing Neutral Current (FCNC) measurements. We find two interesting cases in which our model is phenomenologically viable: (1) the KK-mode of the SM gauge bosons are extremely heavy and unlikely to be produced at the Large Hadron Collider (LHC), while future FCNC measurements can reveal the existence of these heavy modes. (2) the width of the localized SM fermions is very narrow, leading to almost universal 4D KK-mode gauge couplings. In this case, the FCNC constraints can be easily avoided even if a KK gauge boson mass lies at the TeV scale. Such a light KK gauge boson can be searched at the LHC in the near future.

    hep-phhep-thJHEP(2019)·7 citations
21. 21*

    Hints of Modified Gravity in Cosmos and in the Lab?

    Leandros Perivolaropoulos🇬🇷 · Lavrentios Kazantzidis🇬🇷

    General Relativity (GR) is consistent with a wide range of experiments/observations from millimeter scales up to galactic scales and beyond. However, there are reasons to believe that GR may need to be modified because it includes singularities (it is an incomplete theory) and also it requires fine-tuning to explain the accelerating expansion of the universe through the cosmological constant. Thus, it is important to check various experiments and observations beyond the above range of scales for possible hints of deviations from the predictions of GR. If such hints are found it is important to understand which classes of modified gravity theories are consistent with them. The goal of this review is to summarize recent progress on these issues. On sub millimeter scales we show an analysis of the data of the Washington experiment (Kapner et al. (2007)) searching for modifications of Newton's Law on sub-millimeter scales and demonstrate that a spatially oscillating signal is hidden in this dataset. We show that even though this signal cannot be explained in the context of standard modified theories (viable scalar tensor and $f(R)$ theories), it is a rather generic prediction of nonlocal gravity theories. On cosmological scales we review recent analyses of Redshift Space Distortion data which measure the growth rate of cosmological perturbations at various redshifts and show that these data are in some tension with the $\Lambda$CDM parameter values indicated by Planck/2015 CMB data at about 3$\sigma$ level. This tension can be reduced by allowing for an evolution of the effective Newton constant that determines the growth rate of cosmological perturbations. We conclude that even though this tension between the data and the predictions of GR could be due to systematic/statistical uncertainties of the data, it could also constitute early hints of a new gravitational theory.

    ↳ gr-qcastro-ph.COhep-phInt.J.Mod.Phys.D(2019)·49 citations
22. 22*

    Opportunities for lattice QCD in quark and lepton flavor physics

    Christoph Lehner🇺🇸 · Stefan Meinel🇺🇸 · Tom Blum🇺🇸 · Norman H. Christ🇺🇸 · Aida X. El-Khadra🇺🇸 · Maxwell T. Hansen🇨🇭 · Andreas S. Kronfeld🇺🇸 · Jack Laiho🇺🇸 · Ethan T. Neil🇺🇸 · Stephen R. Sharpe🇺🇸 · Ruth S. Van de Water🇺🇸

    This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD in quark and lepton flavor physics. New data generated at Belle II, LHCb, BES III, NA62, KOTO, and Fermilab E989, combined with precise calculations of the relevant hadronic physics, may reveal what lies beyond the Standard Model. We outline a path toward improvements of the precision of existing lattice-QCD calculations and discuss groundbreaking new methods that allow lattice QCD to access new observables.

    ↳ hep-lathep-exhep-phEPJA(2019)·57 citations
23. 23*

    Hadrons and Nuclei

    William Detmold🇺🇸 · Robert G. Edwards🇺🇸 · Jozef J. Dudek🇺🇸 · Michael Engelhardt🇺🇸 · Huey-Wen Lin🇺🇸 · Stefan Meinel🇺🇸 · Kostas Orginos🇺🇸 · Phiala Shanahan🇺🇸

    This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD calculations related to the structure and spectroscopy of hadrons and nuclei. An overview of recent lattice calculations of the structure of the proton and other hadrons is presented along with prospects for future extensions. Progress and prospects of hadronic spectroscopy and the study of resonances in the light, strange and heavy quark sectors is summarized. Finally, recent advances in the study of light nuclei from lattice QCD are addressed, and the scope of future investigations that are currently envisioned is outlined.

    ↳ hep-lathep-phnucl-thEPJA(2019)·104 citations
24. 24*

    A counterexample to the Nelson-Seiberg theorem

    Zheng Sun🇨🇳 · Zipeng Tan🇨🇳 · Lu Yang🇨🇳

    We present a counterexample to the Nelson-Seiberg theorem and its extensions. The model has 4 chiral fields, including one R-charge 2 field and no R-charge 0 filed. Giving generic values of coefficients in the renormalizable superpotential, there is a supersymmetric vacuum with one complex dimensional degeneracy. The superpotential equals zero and the R-symmetry is broken everywhere on the degenerated vacuum. The existence of such a vacuum disagrees with both the original Nelson-Seiberg theorem and its extensions, and can be viewed as the consequence of a non-generic R-charge assignment. Such counterexamples may introduce error to the field counting method for surveying the string landscape, and are worth further investigations.

    ↳ hep-thhep-phJHEP(2020)·12 citations
25. 25*

    Detecting the neutrino mass and mass hierarchy from global data

    Wenxue Zhang🇨🇳 · En-Kun li🇨🇳 · Minghui Du🇨🇳 · Yuhao Mu🇨🇳 · Shouli Ning🇨🇳 · Baorong Chang🇨🇳 · Lixin Xu🇨🇳

    In this paper, we have constrained the neutrino mass and mass hierarchy in the $\Lambda$CDM cosmology with the neutrino mass hierarchy parameter $\Delta$, which represents different mass orderings, by using the {\it Planck} 2015 + BAO + SN + $H_0$ data set, together with the neutrino oscillation and neutrinoless double beta decay data. We find that the mass of the lightest neutrinos and the total neutrino mass are no more than $0.035$eV and $0.133$ eV at $95\%$ confidence level, respectively. Comparing the result of our joint analysis with that obtained using cosmological data alone, we find that, by adding the neutrino oscillation and neutrinoless double beta decay data, the tendency for normal hierarchy has increased a lot. By means of importance sampling, three other priors are taken into account, i.e., the flat logarithmic prior on the absolute value of the neutrino hierarchy parameter $\Delta$, the flat linear prior on the total neutrino mass $\Sigma m_{\nu }$, and the flat logarithmic prior on $\Sigma m_{\nu }$. We find that the preference for the normal hierarchy is in agreement whatever what kinds of priors we choose. Finally, we make a Bayesian model analysis about four priors and we find that flat-linear and the flat logarithmic priors on $\Sigma m_{\nu }$ are the most favored priors.

    ↳ astro-ph.COhep-ph1 citation
26. 26*

    The Role of Lattice QCD in Searches for Violations of Fundamental Symmetries and Signals for New Physics

    Vincenzo Cirigliano🇺🇸 · Zohreh Davoudi🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Taku Izubuchi🇺🇸 · Phiala E. Shanahan🇺🇸 · Sergey Syritsyn🇺🇸 · Michael L. Wagman🇺🇸

    This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for Lattice Quantum Chromodynamics (LQCD) in the research frontier in fundamental symmetries and signals for new physics. LQCD, in synergy with effective field theories and nuclear many-body studies, provides theoretical support to ongoing and planned experimental programs in searches for electric dipole moments of the nucleon, nuclei and atoms, decay of the proton, $n$-$\overline{n}$ oscillations, neutrinoless double-$\beta$ decay of a nucleus, conversion of muon to electron, precision measurements of weak decays of the nucleon and of nuclei, precision isotope-shift spectroscopy, as well as direct dark matter detection experiments using nuclear targets. This whitepaper details the objectives of the LQCD program in the area of Fundamental Symmetries within the USQCD collaboration, identifies priorities that can be addressed within the next five years, and elaborates on the areas that will likely demand a high degree of innovation in both numerical and analytical frontiers of the LQCD research.

    ↳ hep-lathep-exhep-phnucl-ex+1EPJA(2019)·66 citations
27. 27*

    Equivalence between the phase-integral and worldline-instanton methods

    Sang Pyo Kim🇨🇳 · Don N. Page🇨🇦

    The phase-integral and worldline-instanton methods are two widely used methods to calculate Schwinger pair-production densities in electric fields of fixed direction that depend on just one time or space coordinate in the same fixed plane of the electromagnetic field tensor. We show that for charged spinless bosons the leading results of the phase-integral method integrated up through quadratic momenta are equivalent to those of the worldline-instanton method including prefactors. We further apply the phase-integral method to fermion production and time-dependent electric fields parallel to a constant magnetic field.

    ↳ hep-thgr-qchep-ph8 citations
28. 28*

    Reduced Chandrasekhar mass limit due to the fine-structure constant

    Golam Mortuza Hossain🇮🇳 · Susobhan Mandal🇮🇳

    The electromagnetic interaction alters the Chandrasekhar mass limit by a factor which depends, as computed in the literature, on the atomic number of the positively charged nuclei present within the degenerate matter. Unfortunately, the methods employed for such computations break Lorentz invariance ab initio. By employing the methods of finite temperature relativistic quantum field theory, we show that in the leading order, the effect of electromagnetic interaction reduces the Chandrasekhar mass limit for non-general-relativistic, spherically symmetric white dwarfs by a universal factor of $(1-3\alpha /4\pi )$, $\alpha$ being the fine-structure constant.

    ↳ astro-ph.SRgr-qchep-ph2 citations
29. 29*

    Structure of the nucleon and its first radial excitation

    Jorge Segovia🇪🇸

    A Poincaré-covariant continuum approach to the three valence-quark bound-state problem in quantum field theory is used to perform a detailed analysis of the nucleon's ground and first excited states: the so-called $N(940){\frac{1}{2}}^{+}$ and $N(1440){\frac{1}{2}}^{+}$. Such analysis predicts the presence of nonpointlike, fully-interacting quark-quark (diquark) correlations within them, being the isoscalar-scalar and isovector-pseudovector diquarks overwhelmingly dominant with similar relative strengths in both states. Moreover, the rest-frame wave functions of both states are largely $S$-wave in nature and the first excited state in this $1/2^{+}$ channel has the appearance of a radial excitation of the ground state. All these features have numerous observable consequences, we show herein those related with the nucleon's elastic, Roper's elastic and nucleon-to-Roper transition electromagnetic form factors, for both charged and neutral channels.

    ↳ nucl-thhep-exhep-lathep-ph+1Few Body Syst.(2019)·5 citations
30. 30*

    Lattice QCD and Neutrino-Nucleus Scattering

    Andreas S. Kronfeld🇺🇸 · David G. Richards🇺🇸 · William Detmold🇺🇸 · Rajan Gupta🇺🇸 · Huey-Wen Lin🇺🇸 · Keh-Fei Liu🇺🇸 · Aaron S. Meyer🇺🇸 · Raza Sufian🇺🇸 · Sergey Syritsin🇺🇸

    This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD in neutrino-oscillation physics, which inevitably entails nucleon and nuclear structure. In addition to discussing pertinent lattice-QCD calculations of nucleon and nuclear matrix elements, the interplay with models of nuclei is discussed. This program of lattice- QCD calculations is relevant to current and upcoming neutrino experiments, becoming increasingly important on the timescale of LBNF/DUNE and HyperK.

    ↳ hep-lathep-exhep-phnucl-ex+1EPJA(2019)·94 citations
31. 31*

    Lattice Gauge Theory for Physics Beyond the Standard Model

    Richard C. Brower🇺🇸 · Anna Hasenfratz🇺🇸 · Ethan T. Neil🇺🇸 · Simon Catterall🇺🇸 · George Fleming🇺🇸 · Joel Giedt🇺🇸 · Enrico Rinaldi🇺🇸 · David Schaich🇬🇧 · Evan Weinberg🇺🇸 · Oliver Witzel (USQCD Collaboration)🇺🇸

    This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice field theory research to make an impact on models of new physics beyond the Standard Model, including composite Higgs, composite dark matter, and supersymmetric theories.

    ↳ hep-lathep-phhep-thEPJA(2019)·43 citations
32. 32*

    Finite temperature CFT results for all couplings: O(N) model in 2+1 dimensions

    Paul Romatschke🇺🇸

    A famous example of gauge/gravity duality is the result that the entropy density of strongly coupled $\mathcal{N}=4$ SYM in four dimensions for large N is exactly 3/4 of the Stefan-Boltzmann limit. In this work, I revisit the massless O(N) model in 2+1 dimensions, which is analytically solvable at finite temperature $T$ for all couplings $\lambda$ in the large N limit. I find that the entropy density monotonically decreases from the Stefan-Boltzmann limit at $\lambda =0$ to exactly 4/5 of the Stefan-Boltzmann limit at $\lambda =\infty$. Calculating the retarded energy-momentum tensor correlator in the scalar channel at $\lambda =\infty$, I find that it has two logarithmic branch cuts originating at $\omega =\pm 4T\ln \frac{1+\sqrt{5}}{2}$, but no singularities in the whole complex frequency plane. I show that the ratio 4/5 and the location of the branch points both are universal within a large class of bosonic CFTs in 2+1 dimensions.

    ↳ hep-thcond-mat.str-elhep-phnucl-thPRL(2019)·36 citations
33. 33*

    Observing Supernova Neutrino Light Curves with Super-Kamiokande: Expected Event Number over 10 s

    Yudai Suwa (Kyoto Sangyo Univ. & YITP, Kyoto Univ.)🇯🇵 · Kohsuke Sumiyoshi (NIT, Numazu College)🇯🇵 · Ken'ichiro Nakazato (Kyushu Univ.)🇯🇵 · Yasufumi Takahira🇯🇵 · Yusuke Koshio (Okayama Univ.)🇯🇵 · Masamitsu Mori🇯🇵 · Roger A. Wendell (Kyoto Univ.)🇯🇵

    Supernova neutrinos are crucially important to probe the final phases of massive star evolution. As is well known from observations of SN1987A, neutrinos provide information on the physical conditions responsible for neutron star formation and on the supernova explosion mechanism. However, there is still no complete understanding of the long-term evolution of neutrino emission in supernova explosions, although there are a number of modern simulations of neutrino radiation hydrodynamics, which study neutrino emission at times less than one second after the bounce. In the present work we systematically calculate the number of neutrinos that can be observed in Super-Kamiokande over periods longer than ten seconds using the database of Nakazato et al. (2013) anticipating that neutrinos from a Galactic supernova can be detected for several tens of seconds. We find that for a supernova at a distance of 10 kpc, neutrinos remain observable for longer than 30 s for a low-mass neutron star ($1.20M_{\odot }$ gravitational mass) and even longer than 100 s for a high-mass neutron star ($2.05M_{\odot }$). These scenarios are much longer than the observations of SN1987A and longer than the duration of existing numerical simulations. We propose a new analysis method based on the cumulative neutrino event distribution as a function of reverse time from the last observed event, as a useful probe of the neutron star mass. Our result demonstrates the importance of complete modeling of neutrino light curves in order to extract physical quantities essential for understanding supernova explosion mechanisms, such as the mass and radius of the resulting neutron star.

    ↳ astro-ph.HEastro-ph.SRhep-phApJ(2019)·65 citations
34. 34*

    The diverse dark matter density at sub-kiloparsec scales in Milky Way satellites:implications for the nature of dark matter

    Jesús Zavala (1)🇮🇸 · Mark R. Lovell (1,2)🇮🇸 · Mark Vogelsberger (3)🇺🇸 · Jan D. Burger (1) ((1) University of Iceland, (2) Durham, (3) MIT)🇮🇸

    Milky Way (MW) satellites reside within dark matter (DM) subhalos with a broad distribution of circular velocity profiles. This diversity is enhanced with the inclusion of ultra-faint satellites, which seemingly have very high DM densities, albeit with large systematic uncertainties. We argue that if confirmed, this large diversity in the MW satellite population poses a serious test for the structure formation theory with possible implications for the DM nature. For the Cold Dark Matter model, the diversity might be a signature of the combined effects of subhalo tidal disruption by the MW disk and strong supernova feedback. For models with a dwarf-scale cutoff in the power spectrum, the diversity is a consequence of the lower abundance of dwarf-scale halos. This diversity is most challenging for Self-Interacting Dark Matter (SIDM) models with cross sections $\sigma /m_{\chi }\gtrsim 1$cm${}^2$g${}^{-1}$ where subhalos have too low densities to explain the ultra-faint galaxies. We propose a novel solution to explain the diversity of MW satellites based on the gravothermal collapse of SIDM haloes. This solution requires a velocity-dependent cross section that predicts a bimodal distribution of cuspy dense (collapsed) subhaloes consistent with the ultra-faint satellites, and cored lower density subhaloes consistent with the brighter satellites.

    ↳ astro-ph.GAastro-ph.COhep-phPRD(2019)·96 citations
35. 35*

    Constraints on Dark Matter Microphysics from the Milky Way Satellite Population

    Ethan O. Nadler🇺🇸 · Vera Gluscevic🇺🇸 · Kimberly K. Boddy🇺🇸 · Risa H. Wechsler🇺🇸

    Alternatives to the cold, collisionless dark matter (DM) paradigm in which DM behaves as a collisional fluid generically suppress small-scale structure. Herein we use the observed population of Milky Way (MW) satellite galaxies to constrain the collisional nature of DM, focusing on DM-baryon scattering. We first derive analytic upper limits on the velocity-independent DM-baryon scattering cross section by translating the upper bound on the lowest mass of halos inferred to host satellites into a characteristic cutoff scale in the linear matter power spectrum. We then confirm and improve these results through a detailed probabilistic inference of the MW satellite population that marginalizes over relevant astrophysical uncertainties. This yields $95\%$ confidence upper limits on the DM-baryon scattering cross section of $2\times 10^{-29}{\mathrm{cm}}^2$ ($6\times 10^{-27}{\mathrm{cm}}^2$) for DM particle masses $m_{\chi }$ of~$10\mathrm{keV}$ ($10\mathrm{GeV}$); these limits scale as $m_{\chi }^{1/4}$ for $m_{\chi }\ll 1\mathrm{GeV}$ and $m_{\chi }$ for~$m_{\chi }\gg 1\mathrm{GeV}$. This analysis improves upon cosmological bounds derived from cosmic-microwave-background anisotropy measurements by multiple orders of magnitude over a wide range of DM masses, excluding regions of parameter space previously unexplored by other methods, including direct-detection experiments. Our work reveals a mapping between DM-baryon scattering and other alternative DM models, and we discuss the implications of our results for warm and fuzzy DM scenarios.

    ↳ astro-ph.COhep-phApJL(2019)·205 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.