Fri·Dec 15, 2017Friday·December 15, 2017

1. 01*

   Gluino-mediated electroweak penguin with flavor-violating trilinear couplings

   Motoi Endo🇯🇵 · Toru Goto🇯🇵 · Teppei Kitahara🇩🇪 · Satoshi Mishima🇯🇵 · Daiki Ueda🇯🇵 · Kei Yamamoto🇯🇵

   In light of a discrepancy of the direct $CP$ violation in $K\to \pi \pi$ decays, ${\epsilon }^{\prime }/{\epsilon }_K$, we investigate gluino contributions to the electroweak penguin, where flavor violations are induced by squark trilinear couplings. Top-Yukawa contributions to $\Delta S=2$ observables are taken into account, and vacuum stability conditions are evaluated in detail. It is found that this scenario can explain the discrepancy of ${\epsilon }^{\prime }/{\epsilon }_K$ for the squark mass smaller than 5.6 TeV. We also show that the gluino contributions can amplify $\mathcal{B}(K\to \pi \nu \overline{\nu })$, $\mathcal{B}(K_S\to {\mu }^{+}{\mu }^{-}{)}_{\mathrm{eff}}$ and $\Delta A_{\mathrm{CP}}(b\to s\gamma )$. Such large effects could be measured in future experiments.

   hep-phhep-exJHEP(2018)·54 citations
2. 02*

   The bulk Higgs in the Deformed RS Model

   F. Mahmoudi🇫🇷 · N. Manglani🇮🇳 · K. Sridhar🇮🇳

   The Randall-Sundrum model with a deformed metric can generate light Kaluza-Klein (KK) Higgs modes consistent with the electroweak precision analysis for a certain range of parameters. The first KK mode of the Higgs ($h_1$) in such a model could lie in the mass range varying from 800 GeV to 1.3 TeV. We find that the $h_1$ is gaugephobic and decays dominantly into a $t\bar{t}$ pair. The search strategy for $h_1$ decaying to $t\bar{t}$ at the Large Hadron Collider (LHC) in this low mass range has been studies. We have used substructure tools to suppress the large QCD background associated with this channel. We find that $h_1$ can be probed at the LHC.

   hep-phPLB(2018)·3 citations
3. 03*

   Relations between Heavy-light Meson and Quark Masses

   N. Brambilla🇩🇪 · J. Komijani🇩🇪 · A.S. Kronfeld🇺🇸 · A. Vairo🇩🇪

   The study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a merger of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory ($\chi$PT). For practical implementations of this merger, we extend the one-loop $\chi$PT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.

   hep-phhep-lathep-thPRD(2018)·55 citations
4. 04*

   Signal to background interference in $pp\to t{H}^{-}\to t{W}^{-}b\bar{b}$ at the LHC Run-II

   Abdesslam Arhrib🇲🇦 · Rachid Benbrik🇨🇳 · Stefano Moretti🇬🇧 · Rui Santos🇵🇹 · Pankaj Sharma🇦🇺

   We investigate in the Large Hadron Collider (LHC) environment the possibility that sizeable interference effects between a {\sl heavy} charged Higgs boson signal produced via $bg\to t{H}^{-}$ (+ c.c.) scattering and decaying via $H^{-}\to W^{-}A\to W^{-}b\bar{b}$ (+ c.c.) and the irreducible background given by $bg\to t{W}^{-}b\bar{b}$ topologies could spoil current search approaches where the former and latter channels are treated separately. The rationale for this comes from the fact that a heavy charged Higgs state can have a large width, and so can happen for the CP-odd neutral Higgs state emerging in the ensuing decays well, which in turn enables such interferences. We conclude that effects are very significant, both at the inclusive and exclusive level (i.e., both before and after $H^{\pm }$ selection cuts are enforced, respectively) and typically of a destructive nature. This therefore implies that currently established LHC reaches for heavy charged Higgs bosons require some level of rescaling. However, this is possible a posteriori, as the aforementioned $H^{\pm }$ selection cuts shape the interference contributions at the differential level in a way similar to that of the isolated $H^{\pm }$ signal, so there is no need to reassess the efficiency of the individual cuts. We show such effects quantitatively by borrowing benchmarks points from different Yukawa types of a 2-Higgs Doublet Model parameter space for $H^{\pm }$ values starting from around 200 GeV.

   hep-phhep-exPRD(2018)·10 citations
5. 05*

   DAMPE squib? Significance of the 1.4 TeV DAMPE excess

   Andrew Fowlie🇦🇺

   We present a Bayesian and frequentist analysis of the DAMPE charged cosmic ray spectrum. The spectrum, by eye, contained a spectral break at about 1 TeV and a monochromatic excess at about 1.4 TeV. The break was supported by a Bayes factor of about $10^{10}$ and we argue that the statistical significance was resounding. We investigated whether we should attribute the excess to dark matter annihilation into electrons in a nearby subhalo. We found a local significance of about $3.6\sigma$ and a global significance of about $2.3\sigma$, including a two-dimensional look-elsewhere effect by simulating 1000 pseudo-experiments. The Bayes factor was sensitive to our choices of priors, but favoured the excess by about 2 for our choices. Thus, whilst intriguing, the evidence for a signal is not currently compelling.

   hep-phphysics.data-anPLB(2018)·34 citations
6. 06*

   The jet mass distribution after Soft Drop

   Simone Marzani🇮🇹 · Lais Schunk🇫🇷 · Gregory Soyez🇫🇷

   We present a first-principle computation of the mass distribution of jets which have undergone the grooming procedure known as Soft Drop. This calculation includes the resummation of the large logarithms of the jet mass over its transverse momentum, up to next-to-logarithmic accuracy, matched to exact fixed-order results at next-to-leading order. We also include non-perturbative corrections obtained from Monte-Carlo simulations and discuss analytic expressions for hadronisation and Underlying Event effects.

   hep-phEPJC(2018)·78 citations
7. 07*

   Spontaneous SUSY breaking without R-symmetry in supergravity

   Nobuhiro Maekawa🇯🇵 · Yuji Omura🇯🇵 · Yoshihiro Shigekami🇯🇵 · Manabu Yoshida🇯🇵

   We discuss spontaneous supersymmetry (SUSY) breaking in a model with an anomalous $U(1{)}_A$ symmetry. In this model, the size of the each term in the superpotential is controlled by the $U(1{)}_A$ charge assignment and SUSY is spontaneously broken via the Fayet-Iliopoulos of $U(1{)}_A$ at the meta-stable vacuum. In the global SUSY analysis, the gaugino masses become much smaller than the sfermion masses, because an approximate R-symmetry appears at the SUSY breaking vacuum. In this paper, we show that gaugino masses can be as large as gravitino mass, taking the supergravity effect into consideration. This is because the R-symmetry is not imposed so that the constant term in the superpotential, which is irrelevant to the global SUSY analysis, largely contributes to the soft SUSY breaking terms in the supergravity. As the mediation mechanism, we introduce the contributions of the field not charged under $U(1{)}_A$ and the moduli field to cancel the anomaly of $U(1{)}_A$. We comment on the application of our SUSY breaking scenario to the GUT models.

   hep-phPRD(2018)·2 citations
8. 08*

   Prospects for discovery and spin discrimination of dark matter in Higgs portal DM models and their extensions at 100 TeV $pp$ collider

   Bhaskar Dutta🇺🇸 · Teruki Kamon🇺🇸 · P. Ko🇰🇷 · Jinmian Li🇰🇷

   We study the discovery and discriminating prospects of the Higgs portal dark matter (DM) models for scalar, fermion and vector DM and their extensions in proton-proton ($pp$) collisions. The $t\bar{t}+$DM associated production in dileptonic final states is considered, in which the stransverse mass of two leptons is found to be effective in suppressing the Standard Model backgrounds along with the missing transverse energy and the angle between two leptons. The distributions of missing transverse energy and polar angle between two leptons are used for a discrimination of the spin nature of DM. For the proposed benchmark points, the discovery/exclusion can be made with an integrated luminosity less than 1 ab${}^{-1}$ given a 1\% systematic uncertainty, while the spin discrimination require integrated luminosity of a few O(10) ab${}^{-1}$ given a 0.5\% systematic uncertainty. The DM phenomenology is also discussed. A consistent DM candidate can be obtained either by extending our model where the Higgs portal couples to excited dark states that decay into DM, or modifying the coupling form into pseudoscalar.

   hep-phhep-exEPJC(2018)·20 citations
9. 09*

   The strong coupling: a theoretical perspective

   Gavin P. Salam🇨🇭

   This contribution to the volume "From My Vast Repertoire - The Legacy of Guido Altarelli" discusses the state of our knowledge of the strong coupling.

   hep-ph44 citations
10. 10*

    Meromorphic solutions of recurrence relations and DRA method for multicomponent master integrals

    Roman N. Lee🇷🇺 · Kirill T. Mingulov🇷🇺

    We formulate a method to find the meromorphic solutions of higher-order recurrence relations in the form of the sum over poles with coefficients defined recursively. Several explicit examples of the application of this technique are given. The main advantage of the described approach is that the analytical properties of the solutions are very clear (the position of poles is explicit, the behavior at infinity can be easily determined). These are exactly the properties that are required for the application of the multiloop calculation method based on dimensional recurrence relations and analyticity (the DRA method).

    hep-phJHEP(2018)·8 citations
11. 11*

    Chiralspin symmetry and QCD at high temperature

    L. Ya. Glozman🇦🇹

    It has been found very recently on the lattice that at high temperature at vanishing chemical potential QCD is increasingly SU(2)_CS and SU(2N_F) symmetric. We demonstrate that the chemical potential term in the QCD Lagrangian has precisely the same symmetry. Consequently the QCD matter beyond the chiral restoration line on the T - \mu plane is at least approximately SU(2)_CS and SU(2N_F) symmetric.

    hep-phhep-lathep-thnucl-thEPJA(2018)·25 citations
12. 12*

    Mechanism for dark matter depopulation

    Archil Kobakhidze🇦🇺 · Michael A. Schmidt🇦🇺 · Matthew Talia🇦🇺

    Early decoupling of thermally produced dark matter particles due to feeble interactions with the surrounding plasma typically results in their excessive abundance. In this work we propose a simple mechanism for dark matter depopulation. It relies on a specific cosmological evolution under which dark matter particles become temporarily unstable and hence decay away reducing the overall abundance. The instability phase may be followed by an incomplete regeneration phase until the final abundance is established. We explicitly demonstrate this mechanism within a simple toy model of fermionic dark matter and discuss how it can be implemented in theoretically well motivated theories, such as the minimal supersymmetric standard model (MSSM) and for fermionic dark matter in the scotogenic model.

    hep-phPRD(2018)·10 citations
13. 13*

    DREAM, a program for arbitrary-precision computation of dimensional recurrence relations solutions, and its applications

    Roman N. Lee🇷🇺 · Kirill T. Mingulov🇷🇺

    We present the Mathematica package DREAM for arbitrarily high precision computation of multiloop integrals within the DRA (Dimensional Recurrence & Analyticity) method as solutions of dimensional recurrence relations. Starting from these relations, the package automatically constructs the inhomogeneous solutions and reduces the manual efforts to setting proper homogeneous solutions. DREAM also provides means to define the homogeneous solutions of the higher-order recurrence relations (and can construct those of the first-order recurrence relations automatically). Therefore, this package can be used to apply the DRA method to the topologies with sectors having more than one master integral. Two nontrivial examples are presented: four-loop fully massive tadpole diagrams of cat-eye topology and three-loop cut diagrams which are necessary for computation of the width of the para-positronium decay into four photons. The analytical form of this width is obtained here for the first time to the best of our knowledge.

    hep-ph22 citations
14. 14*

    Constraining Elko Dark Matter at the LHC with Monophoton Events

    Alexandre Alves🇧🇷 · M. Dias🇧🇷 · F. de Campos🇧🇷 · L. Duarte🇧🇷 · J. M. Hoff da Silva🇧🇷

    A mass dimension one fermion, also known as Elko, constitutes a dark matter candidate which might interact with photons at the tree level in a specific fashion. In this work, we investigate the constraints imposed by unitarity and LHC data on this type of interactions using the search for new physics in monophoton events. We found that Elkos which can explain the dark matter relic abundance mainly through electromagnetic interactions are excluded at the 95\%CL by the 8 TeV LHC data for masses up to 1 TeV.

    hep-phEPL(2018)·23 citations
15. 15*

    Sneutrino Dark Matter in the BLSSM

    Luigi Delle Rose🇬🇧 · Shaaban Khalil🇪🇬 · Simon J.D. King🇬🇧 · Suchita Kulkarni🇦🇹 · Carlo Marzo🇪🇪 · Stefano Moretti🇬🇧 · Cem S. Un🇹🇷

    In the framework of the $(B-L)$ Supersymmetric Standard Model (BLSSM), we assess the ability of ground and space based experiments to establish the nature of its prevalent Dark Matter (DM) candidate, the sneutrino, which could either be CP-even or -odd. Firstly, by benchmarking this theory construct against the results obtained by the Planck spacecraft, we extract the portions of the BLSSM parameter space compliant with relic density data. Secondly, we show that, based on current sensitivities of the Fermi Large Area Telescope (FermiLAT) and their future projections, the study of high-energy $\gamma$-ray spectra will eventually enable us to extract evidence of this DM candidate through its annihilations into $W^{+}{W}^{-}$ pairs (in turn emitting photons), in the form of both an integrated flux and a differential energy spectrum which cannot be reconciled with the assumption of DM being fermionic (like, e.g., a neutralino), although it should not be possible to distinguish between the scalar and pseudoscalar hypotheses. Thirdly, we show that, while underground direct detection experiments will have little scope in testing sneutrino DM, the Large Hadron Collider (LHC) may be able to do so in a variety of multi-lepton signatures, with and without accompanying jets (plus missing transverse energy), following data collection during Run 2 and 3.

    hep-phJHEP(2018)·42 citations
16. 16*

    General one-loop formulas for decay $h\to Z\gamma$

    L.T. Hue🇻🇳 · A.B. Arbuzov🇷🇺 · T.T. Hong🇻🇳 · T.Phong Nguyen🇻🇳 · D.T. Si🇻🇳 · H.N. Long🇻🇳

    Radiative corrections to the $h\to Z\gamma$ are evaluated in the one-loop approximation. The unitary gauge gauge is used. The analytic result is expressed in terms of the Passarino-Veltman functions. The calculations are applicable for the Standard Model as well for a wide class of its gauge extensions. In particular, the decay width of a charged Higgs boson $H^{\pm }\to W^{\pm }\gamma$ can be derived. The consistence of our formulas and several specific earlier results is shown.

    hep-phEPJC(2018)·24 citations
17. 17*

    Renormalizable SU(5) Completions of a Zee-type Neutrino Mass Model

    Kresimir Kumericki🇭🇷 · Timon Mede🇭🇷 · Ivica Picek🇭🇷

    We explore the potential of a selected model of radiative neutrino masses to be implemented in a renormalizable SU(5) unification framework. The Zee-type model under consideration uncovers the SU(5) representations in which the new fields are embedded and which may contain also other light states leading to the unification of gauge couplings. We perform an exhaustive search which reveals specific patterns of new states and demonstrate that such patterns are consistent with a general choice of relevant scalar potential. It turns out that all of the specific scenarios which lead to successful unification include the colored scalars testable at the LHC.

    hep-phPRD(2018)·18 citations
18. 18*

    A Theory of X and Z Multiquark Resonances

    L. Maiani🇨🇭 · A.D. Polosa🇮🇹 · V. Riquer🇨🇭

    We introduce the hypothesis that diquarks and antidiquarks in tetraquarks are separated by a potential barrier. We show that this notion can answer satisfactorily long standing questions challenging the diquark-antidiquark model of exotic resonances. The tetraquark description of X and Z resonances is shown to be compatible with present limits on the non-observation of charged partners X^+-, of the X(3872) and the absence of a hyperfine splitting between two different neutral states. In the same picture, Z_c and Z_b particles are expected to form complete isospin triplets plus singlets. It is also explained why the decay rate into final states including quarkonia are suppressed with respect to those having open charm/beauty states.

    hep-phPLB(2018)·95 citations
19. 19*

    WCxf: an exchange format for Wilson coefficients beyond the Standard Model

    Jason Aebischer🇩🇪 · Ilaria Brivio🇩🇰 · Alejandro Celis🇩🇪 · Jared A. Evans🇺🇸 · Yun Jiang🇩🇰 · Jacky Kumar🇮🇳 · Xuanyou Pan🇩🇪 · Werner Porod🇩🇪 · Janusz Rosiek🇵🇱 · David Shih🇺🇸 · Florian Staub🇩🇪 · David M. Straub🇩🇪 · Danny van Dyk🇩🇪 · Avelino Vicente🇪🇸

    We define a data exchange format for numerical values of Wilson coefficients of local operators parameterising low-energy effects of physics beyond the Standard Model. The format facilitates interfacing model-specific Wilson coefficient calculators, renormalisation group (RG) runners, and observable calculators. It is designed to be unambiguous (defining a non-redundant set of operators with fixed normalisation in each basis), extensible (allowing the addition of new EFTs or bases by the user), and robust (being based on industry standard file formats with parsers implemented in many programming languages). We have implemented the format for the Standard Model EFT (SMEFT) and for the weak effective theory (WET) below the electroweak scale and have added interfaces to a number of public codes dealing with SMEFT or WET. We also provide command-line utilities and a Python module for convenient manipulation of WCxf files, including translation between different bases and matching from SMEFT to WET.

    hep-phComput.Phys.Commun.(2018)·140 citations
20. 20*

    Analytic results for two-loop Yang-Mills

    David C. Dunbar🇬🇧 · John H Godwin🇬🇧 · Guy R. Jehu🇬🇧 · Warren B. Perkins🇬🇧

    Recent Developments in computing very specific helicity amplitudes in two loop QCD are presented. The techniques focus upon the singular structure of the amplitude rather than on a diagramatic and integration approach

    hep-phPoS(2017)·2 citations
21. 21*

    D-term and structure of point-like and composed spin-0 particles

    Jonathan Hudson🇺🇸 · Peter Schweitzer🇺🇸

    This work deals with form factors of the energy-momentum tensor (EMT) of spin-0 particles and the unknown particle property D-term related to the EMT, and is divided into three parts. The first part explores free, weakly and strongly interacting theories to study EMT form factors with the following findings. (i) The free Klein-Gordon theory predicts for the D-term D = -1. (ii) Even infinitesimally small interactions can drastically impact D. (iii) In strongly interacting theories one can encounter large negative D though notable exceptions exist, which includes Goldstone bosons of chiral symmetry breaking. (iv) Contrary to common belief one cannot arbitrarily add "total derivatives" to the EMT. Rather the EMT must be defined in an unambiguous way. The second part deals with the interpretation of EMT form factors in terms of 3D-densities with following results. (i) The 3D-density formalism is internally consistent. (ii) The description is subject to relativistic corrections which are acceptably small in phenomenologically relevant situations including nucleon and nuclei. (iii) The free field result D=-1 persists when a spin-0 boson is not point-like but "heuristically given some internal structure." The third part investigates the question, whether such "giving of an extended structure" can be implemented dynamically, and has the following insights. (i) We construct a consistent microscopic theory which, in a certain parametric limit, interpolates between extended and point-like solutions. (ii) This theory is exactly solvable which is rare in 3+1 dimensions, admits non-topological solitons of Q-ball-type, and has a Gaussian field amplitude. (iii) The interaction of this theory belongs to a class of logarithmic potentials which were discussed in literature, albeit in different contexts including beyond standard model phenomenology, cosmology, and Higgs physics.

    hep-phPRD(2017)·65 citations
22. 22*

    The dynamic origins of fermionic D-terms

    Jonathan Hudson🇺🇸 · Peter Schweitzer🇺🇸

    The D-term is a particle property defined, similarly to the mass and spin, through matrix elements of the energy-momentum tensor. It is currently not known experimentally for any particle, but the D-term of the nucleon can be inferred from studies of hard-exclusive reactions. In this work we show that the D-term of a spin-1/2 fermion is of dynamical origin: it vanishes for a free fermion. This is in pronounced contrast to the bosonic case where already a free spin-0 boson has a non-zero intrinsic D-term as shown in an accompanying work. We illustrate in two simple models how interactions generate the D-term of a fermion with an internal structure, the nucleon. All known matter is composed of elementary fermions. This indicates the importance to study this interesting particle property in more detail, which will provide novel insights especially on the structure of the nucleon.

    hep-phPRD(2018)·43 citations
23. 23*

    Multi-photon production in the Type-I 2HDM

    Abdesslam Arhrib🇲🇦 · Rachid Benbrik🇲🇦 · Stefano Moretti🇬🇧 · Abdessamad Rouchad🇲🇦 · Qi-Shu Yan🇨🇳 · Xianhui Zhang🇨🇳

    This paper presents a study of a possible contribution to a Higgs boson signal in the $hh\to \gamma \gamma \gamma \gamma$ channel due to $H\to hh$ decays, in the framework of the CP-conserving 2-Higgs Doublet Model Type-I (2HDM-I), where the heavier of the two CP-even Higgs bosons defined herein, $H$, is the SM-like Higgs state observed with a mass of 125 GeV at the Large Hadron Collider (LHC). We perform a broad scan of the 2HDM-I parameter space, in presence of both up-to-date theoretical and experimental constraints, in order to extract the interesting regions yielding such a signal. Then, after validating our numerical framework against public experimental analyses carried out at the LHC, we proceed to assess its scope in constraining and/or extracting the $gg\to H\to hh\to \gamma \gamma \gamma \gamma$ signal in presence of a sophisticated Monte Carlo (MC) simulation. We find that, over a substantial region of the 2HDM-I parameter space presently un-accessible, the LHC will be able to establish such a potential signature in the next 2--3 years.

    hep-phJHEP(2018)·14 citations
24. 24*

    WG1: Structure Functions and Parton Densities

    Lucian Harland-Lang🇬🇧 · Philip Ilten🇺🇸 · Jan Kretzschmar🇬🇧

    This paper gives a summary of selected highlights discussed in the working group on "Structure Functions and Parton Densities" (WG1) at the DIS 2017 conference. From the many talks presented we extract some general themes discussed with respect to global PDF fits, new PDF-sensitive measurements from the LHC experiments and elsewhere, exploitation of new ideas, tools to perform PDF fits, PDFs of heavy nuclei, and finally progress in basic theory calculations.

    hep-phhep-exPoS(2018)·0 citations
25. 25*

    Line-shape analysis of charmonium resonances

    Susana Coito🇵🇱

    We discuss weather the new enhancements found by BES, alias the $Y(4220)$, $Y(4260)$, $Y(4360)$, and $Y(4390)$ are true resonances. We argue that the nearby thresholds $D_s^{\ast }{\bar{D}}_s^{\ast }$, $D{\bar{D}}_1+\bar{D}{D}_1$, $D_s{\bar{D}}_{s1}+\overline{D_s}{D}_{s1}$ and $D^{\ast }{\bar{D}}_1+{\bar{D}}^{\ast }{D}_1$, as well as the $\psi (4160)$ and $\psi (4415)$ states have a strong influence over the observed $J/\psi {\pi }^{+}{\pi }^{-}$ and $h_c{\pi }^{+}{\pi }^{-}$ line-shapes. We propose an unitarized effective Lagrangian model to study the dynamical effect of the interaction between each known $\psi$ state and its closest thresholds. In addition, we present some of our recent motivating results, using the same model, for the $\psi (3770)$ resonance, where the distortion from a Breit-Wigner line-shape is shown to result not only from the kinematic interference, but also from the influence of the $D^0{\bar{D}}^0+D^{+}{D}^{-}$ one-loops. Moreover, two poles were found, at about 3.78 GeV and at 3.74 GeV, the second one generated dynamically, yet contributing to the distortion of the line-shape.

    hep-phPoS(2018)·1 citation
26. 26*

    Revisiting the non-resonant Higgs pair production at the HL-LHC

    Amit Adhikary🇮🇳 · Shankha Banerjee🇬🇧 · Rahool Kumar Barman🇮🇳 · Biplob Bhattacherjee🇮🇳 · Saurabh Niyogi🇮🇳

    We study the prospects of observing the non-resonant di-Higgs pair production in the Standard Model (SM) at the high luminosity run of the 14 TeV LHC (HL-LHC), upon combining multiple final states chosen on the basis of their yield and cleanliness. In particular, we consider the $b\bar{b}\gamma \gamma ,b\bar{b}{\tau }^{+}{\tau }^{-},b\bar{b}W{W}^{\ast },W{W}^{\ast }\gamma \gamma$ and $4W$ channels mostly focusing on final states with photons and/or leptons and study 11 final states. We employ multivariate analyses to optimise the discrimination between signal and backgrounds and find it performing better than simple cut-based analyses. The various differential distributions for the Higgs pair production have non-trivial dependencies on the Higgs self-coupling (${\lambda }_{hhh}$). We thus explore the implications of varying ${\lambda }_{hhh}$ for the most sensitive search channel for the double Higgs production, \textit{viz.}, $b\bar{b}\gamma \gamma$. The number of signal events originating from SM di-Higgs production in each final state is small and for this reason measurement of differential distributions may not be possible. Furthermore, we consider various physics beyond the standard model scenarios to quantify the effects of contamination while trying to measure the SM di-Higgs signals in detail. In particular, we study generic resonant heavy Higgs decays to a pair of SM-like Higgs bosons or to a pair of top quarks, heavy pseudoscalar decaying to an SM-like Higgs and a $Z$-boson, charged Higgs production in association with a top and a bottom quark and also various well-motivated supersymmetric channels. We set limits on the cross-sections for the aforementioned new physics scenarios, above which these can be seen as excesses over the SM background and affect the measurement of Higgs quartic coupling. We also discuss the correlations among various channels which can be useful to identify the new physics model.

    hep-phhep-exJHEP(2018)·67 citations
27. 27*

    Scalar dark matter explanation of the DAMPE data in the minimal Left-Right symmetric model

    Junjie Cao🇨🇳 · Xiaofei Guo🇨🇳 · Liangliang Shang🇨🇳 · Fei Wang🇨🇳 · Peiwen Wu🇰🇷 · Lei Zu🇨🇳

    Left-Right symmetric model (LRSM) has been an attractive extension of the Standard Model (SM) which can address the origin of parity violation in the SM electroweak (EW) interactions, generate tiny neutrino masses, accommodate dark matter (DM) candidates and provide a natural framework for baryogenesis through leptogenesis. In this work we utilize the minimal LRSM to study the recently reported DAMPE results of cosmic $e^{+}{e}^{-}$ spectrum which exhibits a tentative peak around 1.4 TeV, while satisfying the current neutrino data. We propose to explain the DAMPE peak with a complex scalar DM $\chi$ in two scenarios: 1) $\chi {\chi }^{\ast }\to H_1^{++}{H}_1^{--}\to {\ell }_i^{+}{\ell }_i^{+}{\ell }_j^{-}{\ell }_j^{-}$; 2) $\chi {\chi }^{\ast }\to H_k^{++}{H}_k^{--}\to {\ell }_i^{+}{\ell }_i^{+}{\ell }_j^{-}{\ell }_j^{-}$ accompanied by $\chi {\chi }^{\ast }\to H_1^{+}{H}_1^{-}\to {\ell }_i^{+}{\nu }_{{\ell }_i}{\ell }_j^{-}{\nu }_{{\ell }_j}$ with ${\ell }_{i,j}=e,\mu ,\tau$ and $k=1,2$. We fit the theoretical prediction on $e^{+}{e}^{-}$ spectrum to relevant experimental data to determine the scalar mass spectrum favored by the DAMPE excess. We also consider various constraints from theoretical principles, collider experiments as well as DM relic density and direct search experiments. We find that there are ample parameter space which can interpret the DAMPE data while passing the constraints. Our explanations, on the other hand, usually imply the existence of other new physics at the energy scale ranging from $10^7\mathrm{GeV}$ to $10^{11}\mathrm{GeV}$. Collider tests of our explanations are also discussed.

    hep-phastro-ph.HEPRD(2018)·20 citations
28. 28*

    Possible search for dark matter connected to massive standard particles in $e^{+}{e}^{-}$ collisions

    Fernand M. Renard🇫🇷

    We assume that the mass of the heavy standard particles ($Z,W,t,...$) arises from a special coupling with dark matter and that this implies a corresponding peculiar connection of these particles to the dark sector. We give examples of possible tests of this assumption in $e^{+}{e}^{-}\to Z+X,W^{+}{W}^{-}+X,t\bar{t}+X$ and we mention other possible studies.

    hep-ph8 citations
29. 29*

    Non-universal Z' from SO(10) GUTs with vector-like family and the origin of neutrino masses

    Stefan Antusch🇨🇭 · Christian Hohl🇨🇭 · Steve F. King🇬🇧 · Vasja Susic🇨🇭

    A $Z^{\prime }$ gauge boson with mass around the (few) TeV scale is a popular example of physics beyond the Standard Model (SM) and can be a fascinating remnant of a Grand Unified Theory (GUT). Recently, $Z^{\prime }$ models with non-universal couplings to the SM fermions due to extra vector-like states have received attention as potential explanations of the present $R_K$, $R_{K^{\ast }}$ anomalies; this includes GUT model proposals based on the $\mathrm{SO}(10)$ group. In this paper we further develop GUT models with a flavour non-universal low scale $Z^{\prime }$ and clarify several outstanding issues within them. First, we successfully incorporate a realistic neutrino sector (with linear and/or inverse low scale seesaw mechanism), which was so far a missing ingredient. Second, we investigate in detail their compatibility with the $R_K$, $R_{K^{\ast }}$ anomalies; we find that the anomalies do not have a consistent explanation within such models. Third, we demonstrate that these models have other compelling phenomenological features; we study the correlations between the flavour violating processes of $\mu \to 3e$ and $\mu$-$e$ conversion in a muonic atom, showing how a GUT imprint could manifest itself in experiments.

    hep-phNPB(2018)·27 citations
30. 30*

    Texture zeros and hierarchical masses from flavour (mis)alignment

    Wolfgang G. Hollik🇩🇪 · Ulises J. Saldana-Salazar🇩🇪

    We introduce an unconventional interpretation of the fermion mass matrix elements. As the full rotational freedom of the gauge-kinetic terms renders a set of infinite bases called weak bases, basis-dependent structures as mass matrices are unphysical. Matrix invariants, on the other hand, provide a set of basis-independent objects which are of more relevance. We employ one of these invariants to give a new parametrization of the mass matrices. By virtue of it, one gains control over its implicit implications on several mass matrix structures. The key element is the trace invariant which resembles the equation of a hypersphere with a radius equal to the Frobenius norm of the mass matrix. With the concepts of alignment or misalignment we can identify texture zeros with certain alignments whereas Froggatt-Nielsen structures in the matrix elements are governed by misalignment. This method allows further insights of traditional approaches to the underlying flavour geometry.

    hep-phNPB(2018)·6 citations
31. 31*

    swordfish: Efficient Forecasting of New Physics Searches without Monte Carlo

    Thomas D. P. Edwards🇳🇱 · Christoph Weniger🇳🇱

    We introduce swordfish, a Monte-Carlo-free Python package to predict expected exclusion limits, the discovery reach and expected confidence contours for a large class of experiments relevant for particle- and astrophysics. The tool is applicable to any counting experiment, supports general correlated background uncertainties, and gives exact results in both the signal- and systematics-limited regimes. Instead of time-intensive Monte Carlo simulations and likelihood maximization, it internally utilizes new approximation methods that are built on information geometry. Out of the box, swordfish provides straightforward methods for accurately deriving many of the common sensitivity measures. In addition, it allows one to examine experimental abilities in great detail by employing the notion of information flux. This new concept generalizes signal-to-noise ratios to situations where background uncertainties and component mixing cannot be neglected. The user interface of swordfish is designed with ease-of-use in mind, which we demonstrate by providing typical examples from indirect and direct dark matter searches as jupyter notebooks.

    hep-phphysics.data-an24 citations
32. 32*

    $Z$ Boson Decay into Light and Darkness

    M. Fabbrichesi🇮🇹 · E. Gabrielli🇮🇹 · B. Mele🇮🇹

    We study the $Z\to \gamma \bar{\gamma }$ process in which the $Z$ boson decays into a photon $\gamma$ and a massless dark photon $\bar{\gamma }$, when the latter couples to standard-model fermions via dipole moments. This is a simple yet nontrivial example of how the Landau-Yang theorem---ruling out the decay of a massive spin-1 particle into two photons---is evaded if the final particles can be distinguished. The striking signature of this process is a resonant monochromatic single photon in the $Z$-boson center of mass together with missing momentum. LEP experimental bounds allow a branching ratio up to about 10${}^{-6}$ for such a decay. In a simplified model of the dark sector, the dark-photon dipole moments arise from one-loop exchange of heavy dark fermions and scalar messengers. The corresponding prediction for the rare $Z\to \gamma \bar{\gamma }$ decay width can be explored with the large samples of $Z$ bosons foreseen at future colliders.

    hep-phhep-exPRL(2018)·20 citations
33. 33*

    Effects of a neutrino-dark energy coupling on oscillations of high-energy neutrinos

    Niki Klop🇳🇱 · Shin'ichiro Ando🇳🇱

    If dark energy (DE) is a dynamical field rather than a cosmological constant, an interaction between DE and the neutrino sector could exist, modifying the neutrino oscillation phenomenology and causing CP and apparent Lorentz violating effects. The terms in the Hamiltonian for flavor propagation induced by the DE-neutrino coupling do not depend on the neutrino energy, while the ordinary components decrease as $\Delta m^2/E_{\nu }$. Therefore, the DE-induced effects are absent at lower neutrino energies, but become significant at higher energies, allowing to be searched for by neutrino observatories. We explore the impact of the DE-neutrino coupling on the oscillation probability and the flavor transition in the three-flavor framework, and investigate the CP-violating and apparent Lorentz violating effects. We find that DE-induced effects become observable for $E_{\nu }{m}_{\text{eff}}\sim 10^{-20}{\text{GeV}}^2$, where $m_{\mathrm{eff}}$ is the effective mass parameter in the DE-induced oscillation probability, and CP is violated over a wide energy range. We also show that current and future experiments have the sensitivity to detect anomalous effects induced by a DE-neutrino coupling and probe the new mixing parameters. The DE-induced effects on neutrino oscillation can be distinguished from other new physics possibilities with similar effects, through the detection of the directional dependence of the interaction, which is specific to this interaction with DE. However, current experiments will not yet be able to measure the small changes of $\sim 0.03\%$ in the flavor composition due to this directional effect.

    hep-phastro-ph.COPRD(2018)·42 citations
34. 34*

    Higgs-Dilaton Cosmology: An inflation - dark energy connection and forecasts for future galaxy surveys

    Santiago Casas🇩🇪 · Martin Pauly🇩🇪 · Javier Rubio🇩🇪

    The Higgs-Dilaton model is a scale-invariant extension of the Standard Model non-minimally coupled to gravity and containing just one additional degree of freedom on top of the Standard Model particle content. This minimalistic scenario predicts a set of measurable consistency relations between the inflationary observables and the dark-energy equation-of-state parameter. We present an alternative derivation of these consistency relations that highlights the connections and differences with the $\alpha$-attractor scenario. We study in how far these constraints allow to distinguish the Higgs-Dilaton model from $\Lambda$CDM and $w$CDM cosmologies. To this end we first analyze existing data sets using a Markov Chain Monte Carlo approach. Second, we perform forecasts for future galaxy surveys using a Fisher matrix approach, both for galaxy clustering and weak lensing probes. Assuming that the best fit values in the different models remain comparable to the present ones, we show that both Euclid- and SKA2-like missions will be able to discriminate a Higgs-Dilaton cosmology from $\Lambda$CDM and $w$CDM.

    ↳ astro-ph.COgr-qchep-phPRD(2018)·62 citations
35. 35*

    Flavor and energy inference for the high-energy IceCube neutrinos

    Giacomo D'Amico🇮🇹

    We present a flavor and energy inference analysis for each high-energy neutrino event observed by the IceCube observatory during six years of data taking. Our goal is to obtain, for the first time, an estimate of the posterior probability distribution for the most relevant properties, such as the neutrino energy and flavor, of the neutrino-nucleon interactions producing shower and track events in the IceCube detector. For each event the main observables in the IceCube detector are the deposited energy and the event topology (showers or tracks) produced by the Cherenkov light by the transit through a medium of charged particles created in neutrino interactions. It is crucial to reconstruct from these observables the properties of the neutrino which generated such event. Here we describe how to achieve this goal using Bayesian inference and Markov chain Monte Carlo methods.

    ↳ astro-ph.HEhep-phAstropart.Phys.(2018)·8 citations
36. 36*

    Quantum Equivalence of $f(R)$ Gravity and Scalar-tensor Theories in the Jordan and Einstein Frames

    Nobuyoshi Ohta🇯🇵

    The $f(R)$ gravity and scalar-tensor theory are known to be equivalent at the classical level. We study if this equivalence is valid at the quantum level. There are two descriptions of the scalar-tensor theory in the Jordan and Einstein frames. It is shown that these three formulations of the theories give the same determinant or effective action on shell, and thus they are equivalent at the quantum one-loop level on shell in arbitrary dimensions. We also compute the one-loop divergence in $f(R)$ gravity.

    ↳ hep-thastro-ph.COgr-qchep-phPTEP(2018)·51 citations
37. 37*

    Search for time-reversal-invariance violation in double polarized antiproton-deuteron scattering

    Yuriy Uzikov🇷🇺 · Johann Haidenbauer🇩🇪

    Apart from the $pd$ reaction also the scattering of antiprotons with transversal polarization $p_y^p$ on deuterons with tensor polarization $P_{xz}$ provides a null-test signal for time-reversal-invariance violating but parity conserving effects. Assuming that the time-reversal-invariance violating $\bar{N}N$ interaction contains the same operator structure as the $NN$ interaction, we discuss the energy dependence of the null-test signal in $\bar{p}d$ scattering on the basis of a calculation within the spin-dependent Glauber theory at beam energies of 50-300 MeV.

    ↳ nucl-thhep-phEPJ Web Conf.(2018)·0 citations
38. 38*

    Monte-Carlo statistical hadronization in relativistic heavy-ion collisions

    Radoslaw Ryblewski🇵🇱

    A brief introduction to the statistical hadronization approach to particle production in relativistic heavy-ion collisions is given. In the context of fluid dynamics modeling various aspects of hadron emission at the freeze-out are discussed. Practical applications of the presented concepts are presented within the THERMINATOR Monte-Carlo hadron generator.

    ↳ nucl-thhep-phLect.Notes Phys.(2022)·2 citations
39. 39*

    Partial-wave analysis of proton Compton scattering data below the pion-production threshold

    Nadiia Krupina🇩🇪 · Vadim Lensky🇩🇪 · Vladimir Pascalutsa🇩🇪

    Low-energy Compton scattering off the proton is used for determination of the proton polarizabilities. However, the present empirical determinations rely heavily on the theoretical description(s) of the experimental cross sections in terms of polarizabilities. The most recent determinations are based on either the fixed-$t$ dispersion relations (DR) or chiral perturbation theory in the single-baryon sector ($\chi$PT). The two approaches obtain rather different results for proton polarizabilities, most notably for ${\beta }_{M1}$ (magnetic dipole polarizability). We attempt to resolve this discrepancy by performing a partial-wave analysis of the world data on proton Compton scattering below threshold. We find a large sensitivity of the extraction to a few "outliers", leading us to conclude that the difference between DR and $\chi$PT extraction is a problem of the experimental database rather than of "model-dependence". We have specific suggestions for new experiments needed for an efficient improvement of the database. With the present database, the difference of proton scalar polarizabilities is constrainedto a rather broad interval: ${\alpha }_{E1}-{\beta }_{M1}=(6.8\dots 10.9)\times 10^{-4}$ fm${}^3$, with their sum fixed much more precisely [to $14.0(2)$] by the Baldin sum rule.

    ↳ nucl-thhep-phnucl-exPLB(2018)·22 citations
40. 40*

    Super Gaussian enhancers in the Schwinger mechanism

    Ibrahim Akal🇩🇪

    We study the Schwinger mechanism in the presence of an additional uniformly oriented, weak super Gaussian of integer order $4N+2$. Using the worldline approach, we determine the relevant critical points to compute the leading order exponential factor analytically. We show that increasing the parameter $N$ gives rise to a strong dynamical enhancement. For $N=2$, this effect turns out to be larger compared to a weak contribution of Sauter type. For higher orders, specifically, for the rectangular barrier limit, i.e. $N\to \infty$, we approach the Lorentzian case as an upper bound. Although the mentioned backgrounds significantly differ in Minkowski spacetime, we show that the found coincidence applies due to identical reflection points in the Euclidean instanton plane. In addition, we also treat the background in perturbation theory following recent ideas. By doing so, we show that the parameter $N$ determines whether the weak contribution behaves perturbatively or nonperturbatively with respect to the field strength ratio and, hence, reveals an interesting dependence on the background shape. In particular, we show that for backgrounds, for which higher orders in the field strength ratio turn out to be relevant, a proposed integral condition is not fulfilled. In view of these findings, the latter may serve as an indicator for the necessity of higher order contributions.

    ↳ quant-phhep-phhep-thCommun.Theor.Phys.(2020)·2 citations
41. 41*

    Conformal Data of Fundamental Gauge-Yukawa Theories

    Nicola Andrea Dondi🇩🇰 · Vladimir Prochazka🇸🇪 · Francesco Sannino🇩🇰

    We determine central charges, critical exponents and appropriate gradient flow relations for nonsupersymmetric vector-like and chiral Gauge-Yukawa theories that are fundamental according to Wilson and that feature calculable UV or IR interacting fixed points. We further uncover relations and identities among the various local and global conformal data. This information is used to provide the first extensive characterisation of general classes of free and safe quantum field theories of either chiral or vector-like nature via their conformal data. Using large $N_f$ techniques we also provide examples in which the safe fixed point is nonperturbative but for which conformal perturbation theory can be used to determine the global variation of the $a$ central charge.

    ↳ hep-thhep-phPRD(2018)·10 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.