Fri·Nov 30, 2018Friday·November 30, 2018

1. 01*

   Determining the strong coupling: status and challenges

   Antonio Pich🇪🇸 · Juan Rojo🇳🇱 · Rainer Sommer🇩🇪 · Antonio Vairo🇩🇪

   The `XIIIth Quark Confinement and the Hadron Spectrum' conference (Confinement 2018) contained a `Round Table Discussion' on the status of the determinations of the strong coupling ${\alpha }_s(m_Z)$ as well as prospects for future improvements. In this contribution, we summarize the different aspects of the discussion. In particular, we cover ${\alpha }_s$ determinations from inclusive observables, such as the hadronic decays of the $Z$ boson and the $\tau$ lepton; from global fits of parton distribution functions (PDFs); from high-energy collider observables, and from event shapes; as well as from various observables computed by lattice QCD, specifically from the QCD static energy. There is overall good agreement between these various determinations, but there are also outliers, differing from the world average by up to $-5\%$. Nevertheless, the general agreement constitutes a beautiful and significant test of the detailed nature of the strong interactions, and provides a crucial input for high-precision calculations in QCD and beyond.

   hep-phhep-exhep-latPoS(2018)·14 citations
2. 02*

   Axion properties in GUTs

   Anne Ernst🇩🇪 · Luca Di Luzio🇮🇹 · Andreas Ringwald🇩🇪 · Carlos Tamarit🇩🇪

   We summarize recent studies of realistic nonsupersymmetric Grand Unified Theories (GUTs) extended with a global $U(1{)}_{\mathrm{PQ}}$ symmetry, so as to accommodate the axion solution to the strong CP problem. Aside from solving the CP problem and unifying the gauge structure of the SM, these models can also yield realistic spectra and mixings, including neutrino masses, and allowing for a consistent cosmological history that accounts for inflation, dark matter and baryogenesis. In our studies of $SO(10)$ and $SU(5)$ theories, we determined the mass and couplings of the axion in terms of the relevant threshold scales, and assessed how the former are constrained from the requirements of gauge coupling unification, proton decay searches and collider bounds. The axion mass ends up being rather constrained for GUT scale axions, particularly in the case of $SU(5)$, and could be probed by upcoming dark matter experiments, such as ABRACADABRA and CASPEr-Electric.

   hep-phhep-exPoS(2019)·17 citations
3. 03*

   Ansatz for baryonic wave function obtained from a mesonic one

   Alfredo Vega🇨🇱

   Based on ideas that relate meson and baryon spectrum considering SUSY QM and light front holography, we propose a procedure to obtain LFWF for baryons starting from mesonic ones. We apply a procedure suggested for Gaussian ansatz used to study mesons.

   hep-phnucl-th0 citations
4. 04*

   Heavy Higgs as a Portal to the Supersymmetric Electroweak Sector

   Stefania Gori🇺🇸 · Zhen Liu🇺🇸 · Bibhushan Shakya🇺🇸

   The electroweak sector of the Minimal Supersymmetric Standard Model (MSSM) - neutralinos, charginos and sleptons - remains relatively weakly constrained at the LHC due in part to the small production cross sections of these particles. In this paper, we study the prospects of searching for decays of heavy Higgs bosons into these superpartners at the high luminosity LHC. In addition to the kinematic handles offered by the presence of a resonant particle in the production chain, heavy Higgs decays can be the dominant production modes of these superpartners, making it possible to extend coverage to otherwise inaccessible regions of the supersymmetry and heavy Higgs parameter space. We illustrate our ideas with detailed collider analyses of two specific topologies: We propose search strategies for heavy Higgs decay to a pair of neutralinos, which can probe heavy Higgs bosons up to 1 TeV in the intermediate tan $\beta (\sim 2-8)$ region, where standard heavy Higgs searches have no reach. Similarly, we show that targeted searches for heavy Higgs decays into staus can probe stau masses up to several hundred GeV. We also provide a general overview of additional decay channels that might be accessible at the high luminosity LHC. This motivates a broader program for LHC heavy Higgs searches.

   hep-phhep-exJHEP(2019)·21 citations
5. 05*

   A natural $Z^{\prime }$-portal Majorana dark matter in alternative U(1) extended Standard Model

   Nobuchika Okada🇺🇸 · Satomi Okada🇺🇸 · Digesh Raut🇺🇸

   We consider a non-exotic gauged U(1)${}_X$ extension of the Standard Model (SM), where the U(1)${}_X$ charge of a SM field is given by a linear combination of its hypercharge and Baryon-minus-Lepton ($B-L$) number. All the gauge and mixed gauge-gravitational anomalies are cancelled in this model with the introduction of three right-handed neutrinos (RHNs). Unlike the conventional minimal U(1)${}_X$ model, where a universal U(1)${}_X$ charge of $-1$ is assigned to three RHNs, we consider an alternative charge assignment, namely, two RHNs ($N_R^{1,2}$) have U(1)${}_X$ charge $-4$ while one RHN ($N_R$) has a $+5$ charge. With a minimal extension of the Higgs sector, the three RHNs acquire their Majorana masses associated with U(1)${}_X$ symmetry breaking. While $N_R^{1,2}$ have Yukawa coupling with the SM lepton doublets and play an essential role for the 'minimal seesaw' mechanism, $N_R$ is isolated from the SM particles due to its U(1)${}_X$ charge and hence it is a natural candidate for the dark matter (DM) without invoking additional symmetries. In this model context, we investigate the $Z^{\prime }$-portal RHN DM scenario, where the RHN DM communicates with the SM particles through the U(1)${}_X$ gauge boson ($Z^{\prime }$ boson). We identify a narrow parameter space by combining the constraints from the observed DM relic abundance, the results of the search for a $Z^{\prime }$ boson resonance at the Large Hadron Collider Run-2, and the gauge coupling perturbativity up to the Planck/Grand Unification scale. For a special choice of U(1)${}_X$ charges for the SM fields allows us to extend the model to SU(5)$\times$U(1)${}_X$ grand unification. In this scenario, the model parameter space is more severely constrained, which will be explored at future high energy collider experiments.

   hep-phastro-ph.COhep-exPRD(2019)·43 citations
6. 06*

   New vistas in charm production

   Antoni Szczurek🇵🇱

   We discuss some new aspects of charm production trigerred by recent observations of the LHCb collaboration. The LHCb collaboration measured small asymmetries in production of $D^{+}{D}^{-}$ mesons as well as $D_s^{+}{D}_s^{-}$ mesons. Is this related to initial quark/antiquark asymmetries in the proton ? Here we discuss a scenario in which unfavored fragmentations $q/\bar{q}\to D$ and $s/\bar{s}\to D_s$ are responsible for the asymmetries. We fix the strength of such fragmentations -- transition probabilities, by adjusting to the size of the LHCb asymmetries. This has consequences for production of $D$ mesons in forward directions (large $x_F$) as well as at low energies. Large asymmetries are predicted then in these regions. We present here some of our predictions. Consequences for high-energy neutrino production in the atmosphere are discussed and quantified. The production of ${\Lambda }_c$ baryon at the LHC is disussed. Large deviations from the independent-parton fragmentation picture are found.

   hep-phastro-ph.HEEPJ Web Conf.(2019)·0 citations
7. 07*

   Existing and expected manifestations of a new fundamental interaction

   L.M. Slad🇷🇺

   A number of characteristics of the new fundamental interaction are described. The interaction is carried by a massless pseudoscalar boson and extends to at least the electron neutrino, proton, and neutron. A substantiation of the existence of such an interaction is supported by an good agreement between the theoretical and experimental rates of all the five observed processes with solar neutrinos. A bright manifestation of the new interaction is expected in the observation that its contribution to the rate of splitting of a number of light stable nuclei by reactor antineutrinos is approximately six orders of magnitude greater than the contribution of electroweak interaction.

   hep-phastro-ph.SRhep-thnucl-thIJMPE(2021)·3 citations
8. 08*

   Probing leptoquark chirality via top polarization at the Colliders

   Joydeep Roy🇨🇳

   Anomalies in recent LHCb, Belle and Babar measurements of $R_{D^{(\ast )}}$, and $R_{K^{(\ast )}}$ in $B$ decays may indicate the new physics beyond the Standard Model (SM). The leptoquarks ($LQ$) that couple to the $3^{\mathrm{rd}}$ generation quarks and leptons have been proposed as a viable new physics (NP) explanation. Such left-handed $LQ$s can couple to both bottom and top quarks. Since top particles decay before the hadronization, it is possible to reconstruct chirality of boosted top quarks and consequently the chirality of top coupling to the $LQ$s. We perform analysis on the top quark's chirality in the pair-production channel of the $LQ$, which can be purely left-handed in comparison to unpolarized $t\bar{t}$ SM background. We study the prospects of distinguishing the chirality of a potential $LQ$ signal for the high luminosity run of the LHC and other future colliders.

   hep-ph11 citations
9. 09*

   WZ production at the LHC: Polarization observables in the Standard Model

   Julien Baglio🇩🇪 · Le Duc Ninh🇻🇳

   WZ production is an important process at the LHC because it probes the non-Abelian structureof electroweak interactions and it is a background process for many new physics searches. In the quest for new physics, polarization observables of the W and Z bosons can play an important role. They can be extracted from measurements and can be calculated using the Standard Model. In this contribution, we define fiducial polarization observables of the W and Z bosons and discuss the effects of next-to-leading order electroweak and QCD corrections in the Standard Model.

   hep-ph0 citations
10. 10*

    Review of quarkonium production: status and prospects

    Hee Sok Chung🇩🇪

    Production cross sections of heavy quarkonia are considered as useful tools to study various aspects of QCD. We have entered a new era of quarkonium production phenomenology, with the help of new measurements from the LHC giving access to more varieties of observables, and recent theoretical developments that provided us a better understanding of the short-distance process in which quarkonia are produced. With a more concrete understanding of perturbative corrections and a prolific collection of data, a satisfactory description of the quarkonium production mechanism might now be within reach. Unfortunately, the exact mechanism of quarkonium production still remains elusive. Even analyses based on the same formalism can lead to different descriptions of the production process and give contradicting predictions of processes involving heavy quarkonia. This implies that there are much more physics yet to be understood and much work yet to be done in quarkonium production phenomenology. In this paper, we review the current status of theoretical approaches and discuss possible strategies that may improve our understanding of heavy quarkonium production.

    hep-phPoS(2018)·23 citations
11. 11*

    Exploring High Multiplicity Amplitudes: The QM Analogue of the Spontaneously Broken Case

    Joerg Jaeckel🇩🇪 · Sebastian Schenk🇩🇪

    Calculations of high multiplicity Higgs amplitudes exhibit a rapid growth that may signal an end of perturbative behavior or even the need for new physics phenomena. As a step towards this problem we consider the quantum mechanical equivalent of $1\to n$ scattering amplitudes in a spontaneously broken ${\varphi }^4$-theory by extending our previous results on the quartic oscillator with a single minimum to transitions $⟨n|\hat{x}|0⟩$ in the symmetric double-well potential with quartic coupling $\lambda$. Using recursive techniques to high order in perturbation theory, we argue that these transitions are of exponential form $⟨n|\hat{x}|0⟩\sim \exp \left(F(\lambda n)/\lambda \right)$ in the limit of large $n$ and $\lambda n$ fixed. We apply the methods of "exact perturbation theory" put forward by Serone et al. to obtain the exponent $F$ and investigate its structure in the regime where tree-level perturbation theory violates unitarity constraints. We find that the resummed exponent is in agreement with unitarity and rigorous bounds derived by Bachas.

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

    Dimension six effective operators in $t$-channel single top production and decay at NLO in QCD

    Marc de Beurs🇳🇱

    I summarize phenomenological LHC13 studies of the effect of dimension six effective operators on the inclusive cross section and differential distributions for the t-channel single top process at NLO in QCD.

    hep-ph0 citations
13. 13*

    Pair production in differently polarized electric fields with frequency chirps

    Obulkasim Olugh🇨🇳 · Zi-Liang Li🇨🇳 · Bai-Song Xie🇨🇳 · Reinhard Alkofer🇦🇹

    Electron-positron pair production in strong electric fields, i.e., the Sauter-Schwinger effect, is studied using the real-time Dirac-Heisenberg-Wigner formalism. Hereby, the electric field is modeled to be a homogeneous, single-pulse field with subcritical peak field strength. Momentum spectra are calculated for four different polarizations - linear, elliptic, near-circular elliptic or circular - as well as a number of linear frequency chirps. With details depending on the chosen polarization the frequency chirps lead to strong interference effects and thus quite substantial changes in the momentum spectra. The resulting produced pairs' number densities depend non-linearly on the parameter characterizing the polarization and are very sensitive to variations of the chirp parameter. For some of the investigated frequency chirps this can provide an enhancement of the number density by three to four orders of magnitude.

    hep-phPRD(2019)·57 citations
14. 14*

    Exotic Baryons in Chiral Soliton Models

    H. Weigel🇿🇦

    We cautiously review the treatment of pentaquark exotic baryons in chiral soliton models. We consider two examples and argue that any consistent and self-contained description must go beyond the mean field approximation that only considers the classical soliton and the canonical quantization of its (would-be) zero modes via collective coordinates.

    hep-phnucl-thUniverse(2018)·2 citations
15. 15*

    The Phillips - Barger model for the elastic cross section and the Odderon

    V.P. Goncalves🇧🇷 · P.V.R.G. Silva🇧🇷

    Inspired by the recent TOTEM data for the elastic proton -- proton ($pp$) scattering at $\sqrt{s}=$ 8 and 13 TeV, we update previous studies of the differential cross sections using the Phillips -- Barger (PB) model, which parametrizes the amplitude in terms of a small number of free parameters. We demonstrate that this model is able to describe the recent $pp$ data on a statistically acceptable way. Additionally, we perform separate fits of the $pp$ data for each center - of - mass energy and propose a parametrization for the energy dependence of the parameters present in the PB model. As a consequence, we are able to present the PB predictions for the elastic proton - proton cross section at $\sqrt{s}=546$ GeV and $1.8$ TeV, which are compared with the existing antiproton -- proton ($\bar{p}p$) data. We show that the PB predictions, constrained by the $pp$ data, are not able to describe the $\bar{p}p$ data. In particular, the PB model predicts a dip in the differential cross section that is not present in the $\bar{p}p$ data. Such result suggests the contribution of the Odderon exchange at high energies.

    hep-phhep-exEPJC(2019)·27 citations
16. 16*

    SMEFT and the Drell-Yan Process at High Energy

    S. Dawson🇺🇸 · P. P. Giardino🇪🇸 · A. Ismail🇺🇸

    The Drell-Yan process is a copious source of lepton pairs at high energy and is measured with great precision at the Large Hadron Collider (LHC). Barring any new light particles, beyond the Standard Model effects can be studied in Drell-Yan production using an effective field theory. At tree level, new 4-fermion interactions dominate, while at one loop operators modifying 3-gauge boson couplings contribute effects that are enhanced at high energy. We study the sensitivity of the neutral Drell-Yan process to these dimension-6 operators and compare the sensitivity to that of $W^{+}{W}^{-}$ pair production at the LHC.

    hep-phPRD(2019)·71 citations
17. 17*

    Jet fragmentation in a dense QCD medium

    Paul Caucal🇫🇷 · Edmond Iancu🇫🇷 · Alfred H. Mueller🇺🇸 · Gregory Soyez🇫🇷

    We study the fragmentation of a jet propagating in a dense quark-gluon plasma. Using a leading, double-logarithmic approximation in perturbative QCD, we compute for the first time the effects of the medium on the vacuum-like emissions. We show that, due to the scatterings off the plasma, the in-medium parton showers differ from the vacuum ones in two crucial aspects: their phase-space is reduced and the first emission outside the medium can violate angular ordering. We compute the jet fragmentation function and find results in qualitative agreement with measurements at the LHC.

    hep-phnucl-thPoS(2019)·1 citation
18. 18*

    Exact summation of leading infrared logarithms in 2D effective field theories

    Jonas Linzen🇩🇪 · Maxim V. Polyakov🇷🇺 · Kirill M. Semenov-Tian-Shansky🇷🇺 · Nika S. Sokolova🇷🇺

    A method of exact all-order summation of leading infrared logarithms in two dimensional massless ${\Phi }^4$-type non-renormalizable effective field theories (EFTs) is developed. The method is applied to the $\mathrm{O}(N)$-symmetric EFT, which is a two-dimensional sibling of the four dimensional $\mathrm{O}(N+1)/\mathrm{O}(N)$ sigma-model. For the first time the exact all-order summation of the ${\left(E^2\ln (1/E)\right)}^n$ contributions (chiral logarithms) for the $2\to 2$ scattering amplitudes is performed in closed analytical form. The cases when the resulting amplitudes turn to be meromorphic functions with an infinite number of poles (Landau poles) are identified. This provides the first explicit example of quasi-renormalizable field theories.

    hep-phhep-thJHEP(2019)·4 citations
19. 19*

    Multi-winding flux tubes in CFL quark matter

    Alexander Haber🇺🇸 · Andreas Schmitt🇬🇧

    Color-flavor locked quark matter can be described as a three-component superconductor and thus shows unconventional behavior in the transition regime from type-I to type-II superconductivity. We discuss this behavior by studying magnetic line defects in a Ginzburg-Landau approach, taking into account all possible values of the three winding numbers. After a brief discussion of the defects that include baryon circulation we focus on pure magnetic flux tubes. We show that at strong coupling, relevant for neutron stars, type-II behavior is conceivable and the most preferred configuration has minimal total winding. Only at weak coupling we find a regime where multi-winding flux tubes are preferred, although this regime most likely requires an unrealistically large superconducting gap.

    hep-phastro-ph.HEnucl-thPoS(2018)·4 citations
20. 20*

    ExtraOrdinary Gauge Mediation Extension of deflected AMSB

    Fei Wang

    Extraordinary gauge mediation extension of deflected AMSB scenarios can be interesting because it can accommodate together the deflection in the Kahler potential and the superpotential. We revisit the EGM scenario and derive the analytical expressions for soft SUSY breaking parameters in EGM and EGM extension of deflected AMSB scenarios with wavefunction renormalization approach, especially the case with vanishing gauge beta-function at an intermediate energy scale. The Landau pole and proton decay constraints are also discussed.

    hep-phhep-thUniverse(2022)·3 citations
21. 21*

    Lepton Mixing Predictions from $S_4$ in the Tri-Direct CP approach to Two Right-handed Neutrino Models

    Gui-Jun Ding🇨🇳 · Stephen F. King🇬🇧 · Cai-Chang Li🇨🇳

    We perform an exhaustive analysis of all possible breaking patterns arising from $S_4⋊H_{CP}$ in a new {\it tri-direct CP approach} to the minimal seesaw model with two right-handed neutrinos, and construct a realistic flavour model along these lines. According to this approach, separate residual flavour and CP symmetries persist in the charged lepton, `atmospheric' and `solar' right-handed neutrino sectors, i.e. we have {\it three} symmetry sectors rather than the usual two of the {\it semi-direct CP approach} (charged leptons and neutrinos). Following the {\it tri-direct CP approach}, we find twenty-six kinds of independent phenomenologically interesting mixing patterns. Eight of them predict a normal ordering (NO) neutrino mass spectrum and the other eighteen predict an inverted ordering (IO) neutrino mass spectrum. For each phenomenologically interesting mixing pattern, the corresponding predictions for the PMNS matrix, the lepton mixing parameters, the neutrino masses and the effective mass in neutrinoless double beta decay are given in a model independent way. One breaking pattern with NO spectrum and two breaking patterns with IO spectrum corresponds to form dominance. We find that the lepton mixing matrices of three kinds of breaking patterns with NO spectrum and one form dominance breaking pattern with IO spectrum preserve the first column of the tri-bimaximal (TB) mixing matrix, i.e. yield a TM1 mixing matrix.

    hep-phPRD(2019)·21 citations
22. 22*

    Radiative corrections in Dalitz decays of ${\pi }^0$, $\eta$ and ${\eta }^{\prime }$ mesons

    Tomáš Husek🇪🇸

    We briefly summarize current experimental and theoretical results on the two important processes of the low-energy hadron physics involving neutral pions, the rare decay ${\pi }^0\to e^{+}{e}^{-}$ and the Dalitz decay of ${\pi }^0$, and provide a new value for the ratio $R=\Gamma ({\pi }^0\to e^{+}{e}^{-}\gamma (\gamma ))/\Gamma ({\pi }^0\to \gamma \gamma )=11.978(6)\times 10^{-3}$, which is by two orders of magnitude more precise than the current PDG average. This value is obtained using the complete set of the next-to-leading-order radiative corrections in the QED sector, and incorporates up-to-date values of the ${\pi }^0$-transition-form-factor slope. The ratio $R$ translates into the branching ratios of the two main ${\pi }^0$ decay modes: $\mathcal{B}({\pi }^0\to \gamma \gamma )=98.8131(6)\%$ and $\mathcal{B}({\pi }^0\to e^{+}{e}^{-}\gamma (\gamma ))=1.1836(6)\%$. Furthermore, we present the complete set of radiative corrections to the Dalitz decays ${\eta }^{(\prime )}\to {\ell }^{+}{\ell }^{-}\gamma$ beyond the soft-photon approximation, i.e. over the whole range of the Dalitz plot and with no restrictions on the energy of a radiative photon. The corrections inevitably depend on the ${\eta }^{(\prime )}\to {\gamma }^{\ast }{\gamma }^{(\ast )}$ transition form factors. For the singly-virtual transition form factor appearing e.g. in the bremsstrahlung correction, recent dispersive calculations are used. For the one-photon-irreducible contribution at the one-loop level (for the doubly-virtual form factor), we use a vector-meson-dominance-inspired model while taking into account the $\eta$-${\eta }^{\prime }$ mixing.

    hep-phEPJ Web Conf.(2019)·2 citations
23. 23*

    Probing the scalar potential via double Higgs boson production at hadron colliders

    Sophia Borowka🇨🇭 · Claude Duhr🇨🇭 · Fabio Maltoni🇧🇪 · Davide Pagani🇩🇪 · Ambresh Shivaji🇧🇪 · Xiaoran Zhao🇧🇪

    We present a sensitivity study on the cubic and quartic self couplings in double Higgs production via gluon fusion at hadron colliders. Considering the relevant operators in the Standard Model Effective Field Theory up to dimension eight, we calculate the dominant contributions up to two-loop level, where the first dependence on the quartic interaction appears. Our approach allows to study the independent variations of the two self couplings and to clearly identify the terms necessary to satisfy gauge invariance and to obtain UV-finite results order by order in perturbation theory. We focus on the $b\bar{b}\gamma \gamma$ signature for simplicity and provide the expected bounds for the cubic and quartic self couplings at the 14 TeV LHC with 3000 fb${}^{-1}$ (HL-LHC) and for a future 100 TeV collider (FCC-100) with 30 ab${}^{-1}$. We find that while the HL-LHC will provide very limited sensitivity on the quartic self coupling, precision measurements of double Higgs production at a FCC-100 will offer the opportunity to set competitive bounds. We show that combining information from double and triple Higgs production leads to significantly improved prospects for the determination of the quartic self coupling.

    hep-phJHEP(2019)·90 citations
24. 24*

    Partially composite supersymmetry

    Yusuf Buyukdag🇺🇸 · Tony Gherghetta🇺🇸 · Andrew S. Miller🇺🇸

    We consider a supersymmetric model that uses partial compositeness to explain the fermion mass hierarchy and predict the sfermion mass spectrum. The Higgs and third-generation matter superfields are elementary, while the first two matter generations are composite. Linear mixing between elementary superfields and supersymmetric operators with large anomalous dimensions is responsible for simultaneously generating the fermion and sfermion mass hierarchies. After supersymmetry is broken by the strong dynamics, partial compositeness causes the first- and second-generation sfermions to be split from the much lighter gauginos and third-generation sfermions. This occurs even though the tree-level soft masses of the elementary fields are subject to large radiative corrections from the composite sector, which we calculate in the gravitational dual theory using the AdS/CFT correspondence. The sfermion mass scale is constrained by the observed 125 GeV Higgs boson, leading to stop masses and gauginos around 10-100 TeV and the first two generation sfermion masses around 100-1000 TeV. This gives rise to a splitlike supersymmetric model that explains the fermion mass hierarchy while simultaneously predicting an inverted sfermion mass spectrum consistent with LHC and flavor constraints. Finally, the lightest supersymmetric particle is a gravitino in the keV to TeV range, which can play the role of dark matter.

    hep-phPRD(2019)·10 citations
25. 25*

    Mass Hierarchy and Vacuum Energy

    Clifford Cheung🇺🇸 · Prashant Saraswat🇺🇸

    A hierarchically small weak scale does not generally coincide with enhanced symmetry, but it may still be exceptional with respect to vacuum energy. By analyzing the classical vacuum energy as a function of parameters such as the Higgs mass, we show how near-criticality, i.e. fine-tuning, corresponds universally to boundaries where the vacuum energy transitions from exactly flat to concave down. In the presence of quantum corrections, these boundary regions can easily be perturbed to become maxima of the vacuum energy. After introducing a dynamical scalar field $\varphi$ which scans the Higgs sector parameters, we propose several possible mechanisms by which this field could be localized to the maximum. One possibility is that the $\varphi$ potential has many vacua, with those near the maximum vacuum energy expanding faster during a long period of cosmic inflation and hence dominating the volume of the Universe. Alternately, we describe scenarios in which vacua near the maximum could be anthropically favored, due to selection of the late-time cosmological constant or dark matter density. Independent of these specific approaches, the physical value of the weak scale in our proposal is generated naturally and dynamically from loops of heavy states coupled to the Higgs. These states are predicted to be a loop factor heavier than in models without this mechanism, avoiding tension with experimental null results.

    hep-ph40 citations
26. 26*

    Models of hypercolor based on symplectic gauge group with three heavy vectorlike hyperquarks

    N. Volchanskiy🇷🇺 · V. Beylin🇷🇺 · V. Kuksa🇷🇺

    We study possibilities to extend the Standard Model (SM) by three flavors of vectorlike heavy quarks in pseudoreal representation of symplectic hypercolor gauge group. This extension of SM predicts a rich spectra of heavy composite hypermesons and hyperbaryons (all of them carry integer spins) including fourteen pseudo-Nambu--Goldstone states emerging in dynamical breaking of the global symmetry group of the H-quarks, SU(6), to its Sp(6) subgroup. The properties of the lightest states depend strongly on the choice of heavy-quark hypercharges. Our focus is placed on the variants of the model with partially composite Higgs boson, i.e. the experimentally observed boson is comprised of the elementary SM Higgs and a mixture of H-hadrons.

    hep-phInt.J.Mod.Phys.D(2019)·6 citations
27. 27*

    Search for neutral Higgs bosons decaying to $b\bar{b}$ in the flipped 2HDM at future $e^{-}{e}^{+}$ linear colliders

    Majid Hashemi🇮🇷 · Gholamhossein Haghighat🇮🇷

    In this study, assuming the Type-Y (flipped) 2HDM at the SM-like scenario as the theoretical framework, observability of the additional heavy neutral Higgs bosons $H$ and $A$ is investigated through the signal process chain $e^{-}{e}^{+}\to AH\to b\bar{b}b\bar{b}$ at a linear collider operating at the center-of-mass energy of 1.5 TeV. The assumed signal process is highly motivated by the enhancements in the $A/H\to b\bar{b}$ decays at relatively high $\text{tb}$ values. Such enhancements result in the dominance of the mentioned decay modes even for Higgs masses above the threshold of the on-shell top quark pair production. Taking advantage of such a unique feature, several benchmark scenarios are studied. Simulating the detector response based on the SiD detector at the ILC, simulated events are analyzed to reconstruct the $H$ and $A$ Higgs bosons. The top quark pair production and $Z/\gamma$ production are the main SM background processes and are well under control. Results indicate that, the $H$ and $A$ Higgs bosons are observable with signals exceeding $5\sigma$ with possibility of mass measurement in all the tested scenarios. Specifically, the parameter space region enclosed with the mass ranges $m_H$=150-500 GeV and $m_A$=230-580 GeV with the $A/H$ mass splitting of 80 GeV is observable at the integrated luminosity of 500 $f{b}^{-1}$.

    hep-phPRD(2019)·7 citations
28. 28*

    Analysis of the mass and width of the $X(4140)$ as axialvector tetraquark state

    Zhi-Gang Wang🇨🇳 · Zun-Yan Di🇨🇳

    In this article, we construct both the $[sc{]}_T[\bar{s}\bar{c}{]}_A+[sc{]}_A[\bar{s}\bar{c}{]}_T$ type and $[sc{]}_T[\bar{s}\bar{c}{]}_V-[sc{]}_V[\bar{s}\bar{c}{]}_T$ type axialvector currents with $J^{PC}=1^{++}$ to study the mass of the $X(4140)$ with the QCD sum rules. The predicted masses support assigning the $X(4140)$ to be the $[sc{]}_T[\bar{s}\bar{c}{]}_V-[sc{]}_V[\bar{s}\bar{c}{]}_T$ type axialvector tetraquark state. Then we study the hadronic coupling constant $g_{XJ/\psi \varphi }$ with the QCD sum rules based on solid quark-hadron duality, and obtain the decay width $\Gamma (X(4140)\to J/\psi \varphi )=86.9\pm 22.6\mathrm{MeV}$, which is in excellent agreement with the experimental data $83\pm 21_{-14}^{+21}\text{mbox}MeV$ from the LHCb collaboration.

    hep-phEPJC(2019)·43 citations
29. 29*

    Reflective scattering, color conductivity, and centrality in hadron reactions

    S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

    The reflective scattering mode is supposed to play a significant role in hadron interactions at the LHC energy region and beyond. We discuss connection of this mode to the color conducting medium formation in hadron collisions and its role in centrality determination. The issues of centrality in view of the measurements at the LHC are relevant for enlightening the asymptotic dynamics.

    hep-phhep-exJ.Phys.G(2019)·10 citations
30. 30*

    $k$-Strings with exact Casimir law and Abelian-like profiles

    L. E. Oxman🇧🇷 · G. M. Simões🇧🇷

    We explore vortex solutions for a class of dual $SU(N)$ Yang-Mills models with $N^2-1$ Higgs fields in the adjoint representation. Initially, we show that there is a collective behavior that can be expressed in terms of a small $N$-independent number of field profiles. Then, we find a region in parameter space where the nontrivial profiles coincide with those of the Nielsen-Olesen vortex, and the energy scales exactly with the quadratic Casimir. Out of this region, we solve the ansatz equations numerically and find very small deviations from the Casimir law. The coexistence of Abelian-like string profiles and non-Abelian scaling features is welcome, as these properties have been approximately observed in pure YM lattice simulations.

    ↳ hep-thhep-phPRD(2019)·12 citations
31. 31*

    Searches for strongly-produced SUSY at CMS

    Ana Ovcharova (on behalf of the CMS Collaboration)🇺🇸

    Searches for the pair-production of colored supersymmetric particles are presented. The results cover different scenarios of gluino and squark production, including models of split supersymmetry that predict long-lived gluinos, compressed supersymmetric mass spectra characterized by soft decay products as well as models with R-parity violation with low or no missing transverse momentum in the final state. The results are based on proton-proton collisions recorded at $\sqrt{s}=$ 13 TeV with the CMS detector.

    ↳ hep-exhep-phPoS(2019)·0 citations
32. 32*

    Axion Search with Ring Cavity Experiment

    Ippei Obata🇯🇵 · Tomohiro Fujita🇯🇵 · Yuta Michimura🇯🇵

    We suggest a novel experimental method to search for axion dark matter with an optical ring cavity. Our cavity measures the difference of the resonant frequencies between two circular-polarizations of the laser beam. Its technical design adopts double-pass configuration to realize a null experiment and reject environmental common-mode noises. We reveal that it can probe the axion-photon coupling constant with a broad range of axion mass $10^{-17}\text{eV}\lesssim m\lesssim 10^{-10}\text{eV}$, up to several orders of magnitude beyond the current limits. We expect that this cavity experiment establishes a new window to develop the axion research.

    ↳ physics.ins-detastro-ph.COhep-ph0 citations
33. 33*

    Jet tomography in high-energy nuclear collisions

    Ben-Wei Zhang🇨🇳 · Guo-Yang Ma🇨🇳 · Wei Dai🇨🇳 · Sa Wang🇨🇳 · Shan-Liang Zhang🇨🇳

    When an energetic parton traversing the QCD medium, it may suffer multiple scatterings and lose energy. This jet quenching phenomenon may lead to the suppression of leading hadron productions as well as medium modifications of full jet observables in heavy-ion collisions. In this talk we discuss the nuclear modification factors and yield ratios of identified meson such as $\eta$, ${\rho }^0$, $\varphi$, $\omega$, and $K_{\mathrm{S}}^0$ as well as $\pi$ meson at large $p_T$ in A+A collisions at the next-to-leading order (NLO) with high-twist approach of parton energy loss. Then we discuss a newly developed formalism of combing NLO matrix elements and parton shower (PS) for initial hard production with parton energy loss in the QGP, and its application in investigating massive gauge boson ($Z^0$/$W^{\pm }$) tagged jet productions and $b\bar{b}$ dijet correlations in Pb+Pb at the LHC.

    ↳ nucl-thhep-phEPJ Web Conf.(2019)·4 citations
34. 34*

    Revisit of constraints on dark energy with Hubble parameter measurements including future redshift drift observations

    Yan Liu🇨🇳 · Rui-Yun Guo🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    We investigate whether the current Hubble parameter $H(z)$ measurements could help improve the constraints on dark energy on the basis of the mainstream cosmological probes including the type Ia supernovae (SN) observation, the cosmic microwave background anisotropies (CMB) observation, and the baryon acoustic oscillations (BAO) observation. For the current $H(z)$ data, we use 30 data points measured by using a differential age method. Furthermore, we also consider the future $H(z)$ measurements based on the Sandage-Loeb (SL) test by means of the E-ELT in construction, and thus we also use 30 simulated $H(z)$ data according to a 10-year SL test observation. In this work, we choose four typical dark energy models as examples, i.e., the $\Lambda$CDM model, the $w$CDM model, the $\alpha$DE model, and the GCG model, to complete the analysis. We find that, when only the current $H(z)$ data are added, the constraints on these models are not improved compared to the cases using the SN+CMB+BAO data; but when further adding the 10-year SL test data, the constraint results are tremendously improved for all the four models. Therefore, we conclude that, although the current $H(z)$ measurements could not provide an evident improvement on the basis of the current mainstream cosmological probes, the future $H(z)$ measurements from the SL test would have enormous potential to change the status of the Hubble parameter measurements in constraining dark energy.

    ↳ astro-ph.COgr-qchep-phJCAP(2019)·12 citations
35. 35*

    MOND in galaxy groups: a superior sample

    Mordehai Milgrom🇮🇱

    Intermediate-richness galaxy groups are an important test ground for MOND. First, they constitute a distinct type of galactic systems, with their own evolution histories and underlying physical processes; secondly, they probe little-chartered regions of parameter space, as they have baryonic masses similar to massive galaxies, and similar velocity dispersions, but much larger sizes -- similar to cluster cores (or even to clusters), but much lower dispersions. Importantly in the context of MOND, they have the lowest internal accelerations reachable inside galactic systems. I analyze a sample of 56 medium-richness groups having a large number ($\ge 15$) of members with measured velocities. The groups obey the deep-MOND, baryonic-mass-velocity-dispersion relation, $M_{M}G{a}_0=(81/4){\sigma }^4$, with individual, MOND $M_M/L_K$ ratios of order $1$ solar unit, with $(M_M/L_K{)}_{median}=0.7$ s.u. compared with the much larger Newtonian $M_d/L_K$ -- several tens s.u., and $(M_d/L_K{)}_{median}=37$ s.u. The same MOND relation describes dwarf spheroidals -- 2-3 orders smaller in size, and 7-8 orders lower in mass. The groups conformation to the MOND relation is equivalent to their lying on the deep-MOND branch of the `acceleration-discrepancy relation', $g\approx (g_N{a}_0{)}^{1/2}$, for $g$ as low as a few percents of $a_0$ ($g_N$ is the baryonic, Newtonian, gravitational acceleration, and $g$ the actual one). This argues against a breakdown of MOND at extremely low accelerations. This conformation also argues against the hypothesis that the remaining MOND conundrum in cluster cores bespeaks a breakdown of MOND on large-distance scales; our groups are as large as cluster cores, but do not show obvious disagreement with MOND. I also discuss the possible presence of the idiosyncratic, MOND external-field effect.

    ↳ astro-ph.GAgr-qchep-phPRD(2019)·28 citations
36. 36*

    Coarse-graining of the Einstein-Hilbert Action rewritten by the Fisher information metric

    Shingo Takeuchi🇻🇳

    In this study, considering the Fisher information metric (Fisher metric) given by a specific form, which is the form of weights in statistical physics, we rewrite the Einstein-Hilbert (EH) action. Then, determining the transformation rules of the Fisher metric, etc under the coarse-graining, we perform the coarse-graining toward that rewritten EH action. We finally show an existence of a trivial fixed-point. Here, the existence of a trivial fixed-point is not trivial for us because we consider the metric given by the Fisher metric, which is not the normal metric and has to satisfy some constraint in the formalism of the the Fisher metric. We use the path-integral in our analysis. At this time we have to accept that a fundamental constraint in the formalism of the Fisher metric is broken at the quantum level. However we consider we can accept this with the thought that some constraints and causal relations held at the classical level usually get broken at the quantum level. We finds some problems of the Fisher metric. The space-time we consider is two-dimensional.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2020)·0 citations
37. 37*

    Symmetron Scalar Fields: Modified Gravity, Dark Matter or Both?

    Clare Burrage🇬🇧 · Edmund J. Copeland🇬🇧 · Christian Käding🇬🇧 · Peter Millington🇬🇧

    Scalar fields coupled to gravity through the Ricci scalar have been considered both as dark matter candidates and as a possible modified gravity explanation for galactic dynamics. It has recently been demonstrated that the dynamics of baryonic matter in disk galaxies may be explained, in the absence of particle dark matter, by a symmetron scalar field that mediates a fifth force. The symmetron provides a concrete and archetypal field theory within which to explore how large a role modifications of gravity can play on galactic scales. In this article, we extend these previous works by asking whether the same symmetron field can explain the difference between the baryonic and lens masses of galaxies through a modification of gravity. We consider the possibilities for minimal modifications of the model and find that this difference cannot be explained entirely by the symmetron fifth force without extending the field content of the model. Instead, we are pushed towards a regime of parameter space where one scalar field both mediates a fifth force and stores enough energy density that it also contributes to the galaxy's gravitational potential as a dark matter component, a regime which remains to be fully explored.

    ↳ astro-ph.COastro-ph.GAhep-phPRD(2019)·72 citations
38. 38*

    Distinguishing Quarks and Gluons in Pion and Kaon PDFs

    Kyle D. Bednar🇺🇸 · Ian C. Cloët🇺🇸 · Peter C. Tandy🇺🇸

    The leading-twist parton distribution functions of the pion and kaon are calculated for the first time using a rainbow-ladder truncation of QCD's Dyson-Schwinger equations (DSEs) that self-consistently sums all planar diagrams. The non-perturbative gluon dressing of the quarks is thereby correctly accounted for, which in practice means solving the inhomogeneous Bethe-Salpeter equation (BSE) for the quark operator that defines the spin-independent quark distribution functions. An immediate consequence of using this dressed vertex is that gluons carry 35% of the pion's and 30% of the kaon's light-cone momentum, with the remaining momentum carried by the quarks. The scale associated with these DSE results is ${\mu }_0=0.78$GeV. The gluon effects generated by the inhomogeneous BSE are inherently non-perturbative and cannot be mimicked by the perturbative QCD evolution equations. A key consequence of this gluon dressing is that the valence quarks have reduced support at low-to-intermediate $x$, where the gluons dominate, and increased support at large $x$. As a result, our DSE calculation of the pion's valence quark distribution is in excellent agreement with the Conway et al. pion-induced Drell-Yan data, but nevertheless exhibits the $q_{\pi }(x)\simeq (1-x{)}^2$ behavior as $x\to 1$ predicted by perturbative QCD.

    ↳ nucl-thhep-phPRL(2020)·72 citations
39. 39*

    Cosmic distance inference from purely geometric BAO methods: Linear Point standard ruler and Correlation Function Model Fitting

    Stefano Anselmi🇫🇷 · Pier-Stefano Corasaniti🇫🇷 · Ariel G. Sanchez🇩🇪 · Glenn D. Starkman🇺🇸 · Ravi K. Sheth🇺🇸 · Idit Zehavi🇺🇸

    Leveraging the Baryon Acoustic Oscillations (BAO) feature present in clustering 2-point statistics, we aim to measure cosmological distances independently of the underlying background cosmological model. However this inference is complicated by late-time non-linearities that introduce model and tracer dependencies in the clustering correlation function and power spectrum, which must be properly accounted for. With this in mind, we introduce the "Purely-Geometric-BAO," which provides a rigorous tool to measure cosmological distances without assuming a specific background cosmology. We focus on the 2-point clustering correlation function monopole, and show how to implement such an inference scheme employing two different methodologies: the Linear Point standard ruler (LP) and correlation-function model-fitting (CF-MF). For the first time we demonstrate how, by means of the CF-MF, we can measure very precisely the sound-horizon/isotropic-volume-distance ratio, $r_d/D_V(\bar{z})$, while correctly propagating all the uncertainties. Using synthetic data, we compare the outcomes of the two methodologies, and find that the LP provides up to $50\%$ more precise measurements than the CF-MF. Finally, we test a procedure widely employed in BAO analyses: fitting the 2-point function while fixing the cosmological and the non-linear-damping parameters at fiducial values. We find that this underestimates the distance errors by nearly a factor of $2$. We thus recommend that this practice be reconsidered, whether for parameter determination or model selection.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·51 citations
40. 40*

    The Quest for $\mu \to e\gamma$ and its Experimental Limiting Factors at Future High Intensity Muon Beams

    Francesco Renga🇮🇹 · Gianluca Cavoto🇮🇹 · Angela Papa🇮🇹 · Emanuele Ripiccini🇨🇭 · Cecilia Voena🇮🇹

    The search for the Lepton Flavor Violating decay $\mu \to e\gamma$ exploits the most intense continuous muon beams, which can currently deliver $\sim 10^8$ muons per second. In the next decade, accelerator upgrades are expected in various facilities, making it feasible to have continuous beams with an intensity of $10^9$ or even $10^{10}$ muons per second. We investigate the experimental limiting factors that will define the ultimate performances, and hence the sensitivity, in the search for $\mu \to e\gamma$ with a continuous beam at these extremely high rates. We then consider some conceptual detector designs and evaluate the corresponding sensitivity as a function of the beam intensity.

    ↳ hep-exhep-phphysics.ins-detUniverse(2019)·2 citations
41. 41*

    Mixed Non-Gaussianity from Axion-Gauge Field Dynamics

    Tomohiro Fujita🇯🇵 · Ryo Namba🇨🇦 · Ippei Obata🇯🇵

    We study scalar-tensor-tensor cross correlation $⟨\zeta hh⟩$ generated by the dynamics of interacting axion and SU(2) gauge fields during inflation. We quantize the quadratic action and solve the linear equations by taking into account mixing terms in a non-perturbative manner. Combining that with the in-in formalism, we compute contributions from cubic interactions to the bispectrum $B_{\zeta hh}$. We find that the bispectrum is peaked at the folded configuration, which is a unique feature encoded by the scalar mixing and localized production of tensor modes. With our parameter choice, the amplitude of the bispectrum is $k^6{B}_{\zeta hh}\sim 10^{-16}$. The unique shape dependence, together with the parity-violating nature, is thus a distinguishing feature to search for in the CMB observables.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·42 citations
42. 42*

    Ultraviolet Complete Quantum Field Theory and Particle Model

    J. W. Moffat🇨🇦

    An ultraviolet complete particle model is constructed for the observed particles of the standard model. The quantum field theory associates infinite derivative entire functions with propagators and vertices, which make quantum loops finite and maintain Poincaré invariance and unitarity of the model. The electroweak model $SU(2)\times U(1)$ group is treated as a broken symmetry group with non-vanishing experimentally determined boson and fermion masses. A spontaneous symmetry breaking of the vacuum by a scalar Higgs field is not invoked to restore boson and fermion masses to the initially massless $SU(2)\times U(1)$ Lagrangian of the standard model. The hierarchy naturalness problem of the Higgs boson mass is resolved and the model contains only experimentally observed masses and coupling constants. The model can predict a stable vacuum evolution. Experimental tests to distinguish the standard model from the alternative model are proposed. The finite quantum field theory can be extended to quantum gravity.

    ↳ physics.gen-phhep-phhep-thEur.Phys.J.Plus(2019)·16 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.