Wed·May 8, 2019Wednesday·May 8, 2019

1. 01*

   LHC signals of a heavy doublet Higgs as dark matter portal: cut-based approach and improvement with gradient boosting and neural networks

   Atri Dey🇮🇳 · Jayita Lahiri🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   Though the 125-GeV scalar, as the Higgs boson of the standard model, is disfavoured as a dark matter portal by direct searches and the observations on relic density, a heavier scalar in an extended electroweak sector can fit into that role. We explore this possibility in the context of two Higgs doublet models (2HDM). Taking Type I and Type II 2HDM as illustration, and assuming a scalar gauge singlet dark matter particle, we show that the heavy neutral CP-even scalar ($H$) can (a) serve as dark matter portal consistently with all data, and (b) have a substantial invisible branching ratio, over a wide region of the parameter space. Using this fact, we estimate rates of LHC signals where $H$ is produced via ({\it i}) gluon fusion, in association with a hard jet, and ({\it ii}) vector boson fusion. Invisible decays of the $H$ can then lead to monojet + $\text{slashed}{E}_T$ in ({\it i}), and two forward jets with large rapidity gap + $\text{slashed}{E}_T$ in ({\it ii}). The second kind of signal usually yields better significance for the high-luminosity run. We also supplement our cut-based analyses with those based on gradient boosted decision trees (XGboost) and artificial neural network (ANN) techniques, where the statistical significance distinctly improves, especially for Type II 2HDM.

   hep-phhep-exJHEP(2019)·22 citations
2. 02*

   A 3-3-1 model with low scale seesaw mechanisms

   A. E. Cárcamo Hernández🇨🇱 · Yocelyne Hidalgo Velásquez🇨🇱 · Nicolás A. Pérez-Julve🇨🇱

   We construct a viable 3-3-1 model with two $SU(3{)}_L$ scalar triplets, extended fermion and scalar spectrum, based on the $T^{\prime }$ family symmetry and other auxiliary cyclic symmetries, whose spontaneous breaking yields the observed pattern of SM fermion mass spectrum and fermionic mixing parameters. In our model the SM quarks lighter than the top quark, get their masses from a low scale Universal seesaw mechanism, the SM charged lepton masses are produced by a Froggatt-Nielsen mechanism and the small light active neutrino masses are generated from an inverse seesaw mechanism. The model is consistent with the low energy SM fermion flavor data and successfully accommodates the current Higgs diphoton decay rate and predicts charged lepton flavor violating decays within the reach of the forthcoming experiments.

   hep-phEPJC(2019)·44 citations
3. 03*

   Nucleon strangeness polarization from $\Lambda /\bar{\Lambda }$ hyperon production in polarized proton-proton collision at RHIC

   Xiaonan Liu🇨🇳 · Bo-Qiang Ma🇨🇳

   We calculate the inclusive production of a polarized $\Lambda$ or $\bar{\Lambda }$ hyperon from the single longitudinally polarized proton and proton ($pp$) collision at RHIC. By comparing the data reported by the STAR Collaboration, we find that this process is sensitive to the polarization of strange and antistrange quarks of the proton in the experimental range. By introducing asymmetric coefficients with the minimization of ${\chi }^2$, we further identify the asymmetry of the polarized strange-antistrange quarks in the proton sea and find that the first moment is $\Delta s\approx -0.025\pm 0.019$ for strange quark and $\Delta \bar{s}\approx -0.001\pm 0.012$ for antistrange quark, with central values agreeing with the light-cone meson-baryon fluctuation model prediction, the recent lattice QCD determination of strangeness polarization and results from a global QCD analysis given by the Jefferson Lab Angular Momentum (JAM) Collaboration.

   hep-phhep-exEPJC(2019)·7 citations
4. 04*

   Consistency of Gauged Two Higgs Doublet Model: Gauge Sector

   Cheng-Tse Huang🇹🇼 · Raymundo Ramos🇹🇼 · Van Que Tran🇨🇳 · Yue-Lin Sming Tsai🇹🇼 · Tzu-Chiang Yuan🇹🇼

   We study the constraints on the new parameters in the gauge sector of gauged two Higgs doublet model using the electroweak precision test data collected from the Large Electron Positron Collider (LEP) at and off the Z-pole as well as the current Drell-Yan and high-mass dilepton resonance data from the Large Hadron Collider (LHC). Impacts on the new parameters by the projected sensitivities of various electroweak observables at the Circular Electron Positron Collider (CEPC) proposed to be built in China are also discussed. We also clarify why the Stüeckelberg mass $M_Y$ for the hypercharge $U(1{)}_Y$ is set to be zero in the model by showing that it would otherwise lead to the violation of the standard charge assignments for the elementary quarks and leptons.

   hep-phJHEP(2019)·18 citations
5. 05*

   Spin-isospin Kondo effects for ${\Sigma }_c$ and ${\Sigma }_c^{\ast }$ baryons and $\bar{D}$ and ${\bar{D}}^{\ast }$ mesons

   Shigehiro Yasui🇯🇵 · Tomokazu Miyamoto🇯🇵

   We study the Kondo effect for a ${\Sigma }_c$ (${\Sigma }_c^{\ast }$) baryon in nuclear matter. In terms of the spin and isospin ($\mathrm{SU}(2{)}_{\mathrm{spin}}\times \mathrm{SU}(2{)}_{\mathrm{isospin}}$) symmetry, the heavy-quark spin symmetry and the S-wave interaction, we provide the general form of the Lagrangian for a ${\Sigma }_c$ (${\Sigma }_c^{\ast }$) baryon and a nucleon. We analyze the renormalization equation at the one-loop level, and find that the coexistence of spin exchange and isospin exchange magnifies the Kondo effect in comparison with the case where the spin-exchange interaction and the isospin-exchange interaction exist separately. We demonstrate that the solution exists for the ideal sets of the coupling constants, including the $\mathrm{SU}(4)$ symmetry as an extension of the $\mathrm{SU}(2{)}_{\mathrm{spin}}\times \mathrm{SU}(2{)}_{\mathrm{isospin}}$ symmetry. We also conduct a similar analysis for the Kondo effect of a $\bar{D}$ (${\bar{D}}^{\ast }$) meson in nuclear matter. On the basis of the obtained result, we conjecture that there could exist a "mapping" from the heavy meson (baryon) in vacuum onto the heavy baryon (meson) in nuclear matter.

   hep-phcond-mat.str-elnucl-thPRC(2019)·15 citations
6. 06*

   Improved bounds on heavy quark electric dipole moments

   Hector Gisbert🇪🇸 · Joan Ruiz Vidal🇪🇸

   New bounds on the electric dipole moment (EDM) of charm and bottom quarks are derived using the stringent limits on their chromo-EDMs. The new limits, $|d_c|<1.5\times 10^{-21}e\text{cm}$ and $|d_b|<1.2\times 10^{-20}e\text{cm}$, improve the previous ones by about three orders of magnitude. These indirect bounds have implications for different models of new physics, including two-Higgs-doublet, leptoquarks, and supersymmetry models.

   hep-phhep-exPRD(2020)·33 citations
7. 07*

   $X(3872)$ as a four-quark state in a Dyson-Schwinger/Bethe-Salpeter approach

   Paul C. Wallbott🇩🇪 · Gernot Eichmann🇵🇹 · Christian S. Fischer🇩🇪

   We generalise the framework of Dyson-Schwinger and Bethe-Salpeter equations for four-quark states to accommodate the case of unequal quark masses. As a first application, we consider the quantum numbers $I(J^{PC})=0(1^{++})$ of the $X(3872)$ and study the four-quark states with quark contents $cq\bar{q}\bar{c}$ and $cs\bar{s}\bar{c}$. Their Bethe-Salpeter amplitudes are represented by a basis of heavy-light meson-meson, hadro-charmonium and diquark-antidiquark operators, which allows for a dynamical distinction between different internal configurations. In both cases we find the heavy-light meson-meson component to be dominant. For the putative $X(3872)$ we obtain a mass of $3916(74)$ MeV; the corresponding $cs\bar{s}\bar{c}$ state is predicted at $4068(61)$ MeV.

   hep-phhep-latPRD(2019)·44 citations
8. 08*

   Signal versus Background Interference in $H^{+}\to t\bar{b}$ Signals for MSSM Benchmark Scenarios

   Abdesslam Arhrib🇲🇦 · Duarte Azevedo🇵🇹 · Rachid Benbrik🇲🇦 · Hicham Harouiz🇲🇦 · Stefano Moretti🇬🇧 · Riley Patrick🇦🇺 · Rui Santos🇵🇹

   In this paper, we investigate sizeable interference effects between a heavy charged Higgs boson signal produced via $gg\to t\bar{b}{H}^{-}$ (+ c.c.) followed by the decay $H^{-}\to b\bar{t}$ (+ c.c.) and the irreducible background given by $gg\to t\bar{t}b\bar{b}$ topologies at the Large Hadron Collider (LHC). We show how such effects could spoil current $H^{\pm }$ searches where signal and background are normally treated separately. The reason for this is that a heavy charged Higgs boson can have a large total width, in turn enabling such interferences, altogether leading to very significant alterations, both at the inclusive and exclusive level, of the yield induced by the signal alone. This therefore implies that currently established LHC searches for such wide charged Higgs bosons require modifications. We show such effects quantitatively using two different benchmark configurations of the minimal realisation of Supersymmetry, wherein such $H^{\pm }$ states naturally exist.

   hep-phhep-exJHEP(2020)·8 citations
9. 09*

   Flavour from the Planck scale to the electroweak scale

   S.F.King🇬🇧

   We discuss a theory of flavour in which Higgs Yukawa couplings are related to those of the new scalar triplet leptoquark and/or $Z^{\prime }$ responsible for $R_{K^{(\ast )}}$, with all couplings arising effectively from mixing with a vector-like fourth family, whose mass may be anywhere from the Planck scale to the electroweak scale for the leptoquarks explanation, but is pinned down to the TeV scale if the $Z^{\prime }$ exchange plays a role. However, in this particular model, only leptoquark exchange can contribute significantly to $R_{K^{(\ast )}}$, since $Z^{\prime }$ exchange is too constrained from $B_s$ mixing and $\tau \to 3\mu$, although other Higgs Yukawa matrix structures may allow it.

   hep-ph1 citation
10. 10*

    A sub-GeV dark matter model

    Bhaskar Dutta🇺🇸 · Sumit Ghosh🇺🇸 · Jason Kumar🇺🇸

    We propose an extension of the Standard Model gauge symmetry by the gauge group $U(1{)}_{T3R}$ in order to address the Yukawa coupling hierarchy between the third generation fermions and the first two generation fermions of the SM. We assume that only the right-handed fermions of the first two generations are charged under the $U(1{)}_{T3R}$. In addition to the new dark gauge boson, we have a dark scalar particle whose vacuum expectation value (vev) breaks the $U(1{)}_{T3R}$ symmetry down to $Z_2$ symmetry and also explains the hierarchy problem. A vev of $\mathcal{O}$(GeV) is required to explain the mass parameters of the light flavor sector naturally. The dark matter (DM) particle arising from the model naturally has mass in the $\mathcal{O}$(1-100) MeV range. The model satisfies all the current constraints. We discuss the various prospects of the direct detection of the dark matter. We get both elastic and inelastic spin independent DM-nucleon scattering. The dark matter obtains the correct thermal relic density by annihilation.

    hep-phPRD(2019)·64 citations
11. 11*

    Impacts of radiative corrections on measurements of lepton flavour universality in $B\to D\ell {\nu }_{\ell }$ decays

    Stefano Calí🇮🇹 · Suzanne Klaver🇮🇹 · Marcello Rotondo🇮🇹 · Barbara Sciascia🇮🇹

    Radiative corrections to $B\to D\ell {\nu }_{\ell }$ decays may have an impact on predictions and measurements of the lepton flavour universality observables $\mathcal{R}(D^{+})$ and $\mathcal{R}(D^0)$. In this paper, a comparison between recent calculations of the effect of soft-photon corrections on $\mathcal{R}(D^{+})$ and $\mathcal{R}(D^0)$, and corrections generated by the widely used package PHOTOS is given. The impact of long-distance Coulomb interactions, which are not simulated in PHOTOS, is discussed. Furthermore, the effect of high-energy photon emission is studied through pseudo-experiments in an LHCb-like environment. It is found that over- or underestimating these emissions can cause a bias on $\mathcal{R}(D)$ as high as 7%. However, this bias depends on individual analyses, and future high precision measurements require an accurate evaluation of these QED corrections.

    hep-phhep-exEPJC(2019)·26 citations
12. 12*

    Resolving the tensor structure of the Higgs coupling to $Z$-bosons via Higgs-strahlung

    Shankha Banerjee🇬🇧 · Rick S. Gupta🇬🇧 · Joey Y. Reiness🇬🇧 · Michael Spannowsky🇬🇧

    We propose differential observables for $pp\to Z({\ell }^{+}{\ell }^{-})h(b\bar{b})$ that can be used to completely determine the tensor structure of the $hZ{Z}^{\ast }/hZ\bar{f}f$ couplings relevant to this process in the dimension-6 SMEFT. In particular, we propose a strategy to probe the anomalous $h{Z}_{\mu \nu }{Z}^{\mu \nu }$ and $h{Z}_{\mu \nu }{\tilde{Z}}^{\mu \nu }$ vertices at the percent level. We show that this can be achieved by resurrecting the interference term between the transverse $Zh$ amplitude, which receives contributions from the above couplings, and the dominant SM longitudinal amplitude. These contributions are hard to isolate without a knowledge of the analytical amplitude, as they vanish unless the process is studied differentially in three different angular variables at the level of the $Z$-decay products. By also including the differential distributions with respect to energy variables, we obtain projected bounds for the two other tensor structures of the Higgs coupling to $Z$-bosons.

    hep-phhep-exPRD(2019)·43 citations
13. 13*

    Analysis of the $P_c(4312)$, $P_c(4440)$, $P_c(4457)$ and related hidden-charm pentaquark states with QCD sum rules

    Zhi-Gang Wang🇨🇳

    In this article, we restudy the ground state mass spectrum of the diquark-diquark-antiquark type $uudc\bar{c}$ pentaquark states with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of $13$ in a consistent way. The predicted masses support assigning the $P_c(4312)$ to be the hidden-charm pentaquark state with $J^P={\frac{1}{2}}^{-}$, assigning the $P_c(4440)$ to be the hidden-charm pentaquark state with $J^P={\frac{1}{2}}^{-}$, ${\frac{3}{2}}^{-}$ or ${\frac{5}{2}}^{-}$, assigning the $P_c(4457)$ to be the hidden-charm pentaquark state with $J^P={\frac{1}{2}}^{-}$ or ${\frac{3}{2}}^{-}$.

    hep-phInt.J.Mod.Phys.A(2020)·153 citations
14. 14*

    On-shell renormalization scheme for $\mathcal{N}=1$ SQED and the NSVZ relation

    A.L.Kataev🇷🇺 · A.E.Kazantsev🇷🇺 · K.V.Stepanyantz🇷🇺

    In this paper we investigate the renormalization of $\mathcal{N}=1$ supersymmetric quantum electrodynamics, regularized by higher derivatives, in the on-shell scheme. It is demonstrated that in this scheme the exact Novikov, Shifman, Vainshtein, and Zakharov (NSVZ) equation relating the $\beta$-function to the anomalous dimension of the matter superfields is valid in all orders of the perturbation theory. This implies that the on-shell scheme enters the recently constructed continuous set of NSVZ subtraction schemes. To verify this statement, we compare the anomalous dimension of the matter superfields in the two-loop approximation and the $\beta$-function in the three-loop approximation, which are explicitly calculated in this scheme. The finite renormalizations relating the on-shell scheme to some other NSVZ subtraction schemes formulated previously are obtained.

    ↳ hep-thhep-phEPJC(2019)·26 citations
15. 15*

    Revisiting Ryskin's Model of Cosmic Acceleration

    Zhiqi Huang🇨🇳 · Han Gao🇨🇳 · Haoting Xu🇨🇳

    Cosmic backreaction as an additional source of the expansion of the universe has been a debate topic since the discovery of cosmic acceleration. The major concern is whether the self interaction of small-scale nonlinear structures would source gravity on very large scales. Gregory Ryskin argued against the additional inclusion of gravitational interaction energy of astronomical objects, whose masses are mostly inferred from gravitational effects and hence should already contain all sources with long-range gravity forces. Ryskin proposed that the backreaction contribution to the energy momentum tensor is instead from the rest of the universe beyond the observable patch. Ryskin's model elegantly solves the fine-tuning problem and is in good agreement with the Hubble diagram of Type Ia supernovae. In this article we revisit Ryskin's model and show that it is {\it inconsistent} with at least one of the following statements: (i) the universe is matter-dominated at low redshift ($z\lesssim 2$); (ii) the universe is radiation-dominated at sufficiently high redshift; (iii) matter density fluctuations are tiny ($\lesssim 10^{-4}$) at the recombination epoch.

    ↳ astro-ph.COgr-qchep-phhep-thAstropart.Phys.(2020)·2 citations
16. 16*

    Testing the Swampland: $H_0$ tension

    Eoin Ó Colgáin🇰🇷 · Hossein Yavartanoo🇨🇳

    The de Sitter Swampland conjecture compels us to consider dark energy models where $\lambda (\varphi )\equiv |{\nabla }_{\varphi }V|/V$ is bounded below by a positive constant. Moreover, it has been argued for Quintessence models that the constant $\lambda$ scenario is the least constrained. Here we demonstrate that increasing $\lambda$ only exacerbates existing tension in the Hubble constant $H_0$. The identification of dark energy models that both evade observational bounds and alleviate $H_0$ tension constitutes a robust test for the Swampland program.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2019)·102 citations
17. 17*

    Holographic conformal transition and light scalars

    Alex Pomarol🇪🇸 · Oriol Pujolas🇪🇸 · Lindber Salas🇪🇸

    We present an holographic approach to strongly-coupled theories close to the conformal to non-conformal transition, trying to understand the presence of light scalars as recent lattice simulations seem to suggest. We find that the dilaton is always the lightest resonance, although not parametrically lighter than the others. We provide a simple analytic formula for the dilaton mass that allows us to understand this behavior. The pattern of the meson mass spectrum, as we get close to the conformal transition, is found to be quite similar to that in lattice simulations. We provide further predictions from holography that can be checked in the future.These five-dimensional models can also implement new solutions to the hierarchy problem, having implications for searches at the LHC and cosmology.

    ↳ hep-thhep-lathep-phJHEP(2019)·56 citations
18. 18*

    Constraining the Self-Interacting Neutrino Interpretation of the Hubble Tension

    Nikita Blinov🇺🇸 · Kevin J. Kelly🇺🇸 · Gordan Krnjaic🇺🇸 · Samuel D. McDermott🇺🇸

    Large, non-standard neutrino self-interactions have been shown to resolve the $\sim 4\sigma$ tension in Hubble constant measurements and a milder tension in the amplitude of matter fluctuations. We demonstrate that interactions of the necessary size imply the existence of a force-carrier with a large neutrino coupling ($>10^{-4}$) and mass in the keV -- 100 MeV range. This mediator is subject to stringent cosmological and laboratory bounds, and we find that nearly all realizations of such a particle are excluded by existing data unless it carries spin 0 and couples almost exclusively to $\tau$-flavored neutrinos. Furthermore, we find that the light neutrinos must be Majorana, and that a UV-complete model requires a non-minimal mechanism to simultaneously generate neutrino masses and appreciable self-interactions.

    ↳ astro-ph.COhep-exhep-phPRL(2019)·239 citations
19. 19*

    A Weak Gravity Theorem

    Mehrdad Mirbabayi🇮🇹

    In a gravitational theory with a massless photon the maximum charge-to-mass ratio of black holes approaches the prediction of the Einstein-Maxwell theory as black hole mass increases: $Q_{\mathrm{ext}}/M=1+\alpha /M^2$ for some constant $\alpha$. We will show that $\alpha >0$ if below the quantum gravity scale $\Lambda$ there are many degrees of freedom with a hierarchically small mass gap $\log (\Lambda /m_{\mathrm{gap}})\gg 1$. In this regime one can treat gravity as a non-dynamical background field and derive field-theoretic sum-rules for the coefficients of the leading corrections to the Einstein-Maxwell theory. The positivity of $\alpha$ follows from the sum-rules. As a consequence, gravitational attraction gets weaker than the electric force among maximally charged black holes as they become lighter, and large extremal black holes can decay into smaller black holes.

    ↳ hep-thastro-ph.COgr-qchep-ph7 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.