Mon·Jun 19, 2017Monday·June 19, 2017

1. 01*

   The Leptoquark Hunter's Guide: Pair Production

   Bastian Diaz🇨🇱 · Martin Schmaltz🇺🇸 · Yi-Ming Zhong🇺🇸

   Leptoquarks occur in many new physics scenarios and could be the next big discovery at the LHC. The purpose of this paper is to point out that a model-independent search strategy covering all possible leptoquarks is possible and has not yet been fully exploited. To be systematic we organize the possible leptoquark final states according to a leptoquark matrix with entries corresponding to nine experimentally distinguishable leptoquark decays: any of {light-jet, b-jet, top} with any of {neutrino, $e/\mu$, $\tau$}. The 9 possibilities can be explored in a largely model-independent fashion with pair-production of leptoquarks at the LHC. We review the status of experimental searches for the 9 components of the leptoquark matrix, pointing out which 3 have not been adequately covered. We plead that experimenters publish bounds on leptoquark cross sections as functions of mass for as wide a range of leptoquark masses as possible. Such bounds are essential for reliable recasts to general leptoquark models. To demonstrate the utility of the leptoquark matrix approach we collect and summarize searches with the same final states as leptoquark pair production and use them to derive bounds on a complete set of Minimal Leptoquark models which span all possible flavor and gauge representations for scalar and vector leptoquarks.

   hep-phhep-exJHEP(2017)·186 citations
2. 02*

   A New Viable Region of Inert Higgs Doublet Dark Matter Model with Scotogenic Extension

   Debasish Borah🇮🇳 · Aritra Gupta🇮🇳

   We explore the intermediate dark matter mass regime of the inert Higgs doublet model (IHDM) by extending the model with three copies of right handed singlet neutrinos. The in built discrete $Z_2$ symmetry of the model allows these right handed neutrinos to couple to the usual lepton doublets through the inert Higgs doublet allowing the possibility of radiative neutrino mass in the scotogenic fashion. Apart from generating non-zero neutrino mass, such an extension can also revive the intermediate dark matter mass regime, between $W$ boson mass to a few hundred GeV's where pure IHDM can not give rise to correct dark matter relic abundance. The late decay of the lightest right handed neutrino to dark matter makes it possible for the usual thermally under-abundant dark matter in this intermediate mass regime to satisfy the correct relic abundance limit. The revival of this wide intermediate mass range can not only have relevance for direct search experiments but also for neutrino experiments as the long lifetime of the lightest right handed neutrino also results in almost vanishing lightest neutrino mass.

   hep-phPRD(2017)·61 citations
3. 03*

   Two-photon interactions with Majorana fermions

   David C. Latimer🇺🇸

   Because Majorana fermions are their own antiparticles, their electric and magnetic dipole moments must vanish, leaving the anapole moment as their only static electromagnetic property. But the existence of induced dipole moments is not necessarily prohibited. Through a study real Compton scattering, we explore the constraints that the Majorana fermion's self-conjugate nature has on induced moments. In terms of the Compton amplitude, we find no constraints if the interactions are separately invariant under charge conjugation, parity, and time reversal. However, if the interactions are odd under parity and even under time reversal, then these contributions to the Compton amplitude must vanish. We employ a simple model to confirm these general findings via explicit calculation of the Majorana fermion's polarizabilities. We then use these polarizabilities to estimate the cross-section for $s$-wave annihilation of two Majorana fermions into photons. The cross-section is larger than a naïve estimate might suggest.

   hep-phhep-thPRD(2016)·14 citations
4. 04*

   Light-Cone Distribution Amplitudes of Light $J^{PC}=2^{--}$ Tensor Mesons in QCD

   T.M.Aliev🇹🇷 · S.Bilmis🇹🇷 · Kwei-Chou Yang🇹🇼

   We present a study for two-quark light-cone distribution amplitudes for the $1^3{D}_2$ light tensor meson states with quantum number $J^{PC}=2^{--}$. Because of the G-parity, the chiral-even two-quark light-cone distribution amplitudes of this tensor meson are antisymmetric under the interchange of momentum fractions of the quark and antiquark in the SU(3) limit, while the chiral-odd ones are symmetric. The asymptotic leading-twist LCDAs with the strange quark mass correction are shown. We estimate the relevant parameters, the decay constants $f_T$ and $f_T^{\perp }$, and first Gegenbauer moment $a_1^{\perp }$, by using the QCD sum rule method. These parameters play a central role in the investigation of $B$ meson decaying into the $2^{--}$ tensor mesons.

   hep-phNPB(2018)·7 citations
5. 05*

   Investigation of pion-induced $f_1(1285)$ production off a nucleon target within an interpolating Reggeized approach

   Xiao-Yun Wang🇨🇳 · Jun He🇨🇳

   In this work, the pion-induced $f_1(1285)$ production off a nucleon target is investigated in an effective Lagrangian approach with an interpolating Reggeized treatment in a large range of the pion-beam momentum from threshold up to several tens of GeV. The $s$-channel, $u$-channel, and $t$-channel Born terms are included to calculate production cross sections. An interpolating Reggeized treatment is applied to the $t$ channel, which is found to be important to reproduce the behavior of the existent experimental total cross sections at both low ($\lesssim$ 8 GeV) and high pion-beam momenta ($\gtrsim$ 8 GeV). It is found that the $t$-channel contribution is dominant in the pion-induced $f_1(1285)$ production at low beam momentum and still dominant at very forward angles at high momentum. The interpolated Reggeized treatment of the $u$ channel is also discussed. The $u$-channel contribution is small and negligible at low momentum, and it becomes dominant at backward angles at momenta higher than 10 GeV. The differential cross sections are predicted with the model fixed by the fitting existent experimental data. The results are helpful to the possible experiments at J-PARC and COMPASS.

   hep-phhep-exnucl-exPRD(2017)·14 citations
6. 06*

   Importance of thermodynamic fluctuations in the Gazdzicki Gorenstein model

   Kacper Zalewski🇵🇱

   Effects of the standard thermodynamic fluctuations on the predictions of the Gazdzicki Gorenstein model of particle production in high-energy heavy ion collisins are evaluated. At low numbers of participating nucleons the corrections due to these fluctuations are found to be very significant.

   hep-phActa Phys.Polon.B(2017)·0 citations
7. 07*

   Generalized Clockwork Theory

   Ido Ben-Dayan🇮🇱

   We generalize the clockwork theory in several directions. First, we consider beyond nearest neighbors interactions. Considering such interactions keeps a larger subgroup of the original $U(1{)}^{N+1}$ unbroken and can allow for different symmetry breaking patterns. We recover the original clockwork scenario in the presence of these additional interactions. In such case, the masses of the massive modes change, but a single massless mode remains intact. Such interactions are naturally interpreted as higher derivative terms from the point of view of extra dimensions. Second, we generalize the clockwork shift symmetry to non-abelian global groups. Third, trivial embedding of the clockwork scenario in supergravity, yields an AdS minimum as big as the clockwork interaction. Specifically, the clockwork is connected to the cosmological constant. We analyze the different ways in which a Minkowski supersymmetric minimum can be constructed, and demonstrate simple SUSY breaking mechanisms that preserve or break the clockwork symmetry. We show that the clockwork direction is actually a special SUSY breaking direction, that does not require the inclusion of additional fields or parameters. Fourth, we review the extra-dimensional origin of the mechanism and interpretation, in the case of conformal coupling to gravity.

   hep-phhep-thPRD(2019)·25 citations
8. 08*

   Probing Squeezed Bino-Slepton Spectra with the Large Hadron Collider

   Bhaskar Dutta🇺🇸 · Kebur Fantahun🇺🇸 · Ashen Fernando🇺🇸 · Tathagata Ghosh🇺🇸 · Jason Kumar🇺🇸 · Pearl Sandick🇺🇸 · Patrick Stengel🇺🇸 · Joel W. Walker🇺🇸

   We consider a Minimal Supersymmetric Standard Model scenario in which the only light superparticles are a bino-like dark matter candidate and a nearly-degenerate slepton. It is notoriously difficult to probe this scenario at the Large Hadron Collider, because the slepton pair-production process yields a final state with soft leptons and small missing transverse energy. We study this scenario in the region of parameter space where the mass difference between the lightest neutralino and the lightest slepton ($\Delta m$) is $\lesssim 60\mathrm{GeV}$, focusing on the process in which an additional radiated jet provides a transverse boost to the slepton pair. We then utilize the angular separation of the leptons from each other and from the missing transverse energy, as well as the angular separation between the jet and the missing transverse energy, to distinguish signal from background events. We also use the reconstructed ditau mass, the $\cos {\theta }_{{\ell }^{+}{\ell }^{-}}^{\ast }$ variable, and for larger $\Delta m$, a lower bound on the lepton $p_T$. These cuts can dramatically improve both signal sensitivity and the signal-to-background ratio, permitting discovery at the Large Hadron Collider with reasonable integrated luminosity over the interesting region of parameter space. Using our search strategy the LHC will be able to exclude $m_{\tilde{\mu }}\approx 200$ GeV for $\Delta m\lesssim 60$ GeV at $1.5-3\sigma$ with 1000 fb${}^{-1}$ of integrated luminosity. Although we focus on a particular model, the results generalize to a variety of scenarios in which the dark matter and a leptonic partner are nearly degenerate in mass, and especially to scenarios featuring a scalar mediator.

   hep-phPRD(2017)·16 citations
9. 09*

   Supersymmetric and non-supersymmetric models without catastrophic Goldstone bosons

   Johannes Braathen🇫🇷 · Mark D. Goodsell🇫🇷 · Florian Staub🇩🇪

   The calculation of the Higgs mass in general renormalisable field theories has been plagued by the so-called "Goldstone Boson Catastrophe", where light (would-be) Goldstone bosons give infra-red divergent loop integrals. In supersymmetric models, previous approaches included a workaround that ameliorated the problem for most, but not all, parameter space regions; while giving divergent results everywhere for non-supersymmetric models! We present an implementation of a general solution to the problem in the public code SARAH, along with new calculations of some necessary loop integrals and generic expressions. We discuss the validation of our code in the Standard Model, where we find remarkable agreement with the known results. We then show new applications in Split SUSY, the NMSSM, the Two-Higgs-Doublet Model, and the Georgi-Machacek model. In particular, we take some first steps to exploring where the habit of using tree-level mass relations in non-supersymmetric models breaks down, and show that the loop corrections usually become very large well before naive perturbativity bounds are reached.

   hep-phEPJC(2017)·78 citations
10. 10*

    Lattice QCD exploration of pseudo-PDFs

    Kostas Orginos🇺🇸 · Anatoly Radyushkin🇺🇸 · Joseph Karpie🇺🇸 · Savvas Zafeiropoulos🇺🇸

    We demonstrate a new method of extracting parton distributions from lattice calculations. The starting idea is to treat the generic equal-time matrix element $\mathcal{M}(P{z}_3,z_3^2)$ as a function of the Ioffe time $\nu =P{z}_3$ and the distance $z_3$. The next step is to divide $\mathcal{M}(P{z}_3,z_3^2)$ by the rest-frame density $\mathcal{M}(0,z_3^2)$. Our lattice calculation shows a linear exponential $z_3$-dependence in the rest-frame function, expected from the $Z(z_3^2)$ factor generated by the gauge link. Still, we observe that the ratio $\mathcal{M}(P{z}_3,z_3^2)/\mathcal{M}(0,z_3^2)$ has a Gaussian-type behavior with respect to $z_3$ for 6 values of $P$ used in the calculation. This means that $Z(z_3^2)$ factor was canceled in the ratio. When plotted as a function of $\nu$ and $z_3$, the data are very close to $z_3$-independent functions. This phenomenon corresponds to factorization of the $x$- and $k_{\perp }$-dependence for the TMD $\mathcal{F}(x,k_{\perp }^2)$. For small $z_3\le 4a$, the residual $z_3$-dependence is explained by perturbative evolution, with ${\alpha }_s/\pi =0.1$.

    hep-phhep-latPRD(2017)·314 citations
11. 11*

    Phenomenology of ELDER Dark Matter

    Eric Kuflik🇺🇸 · Maxim Perelstein🇺🇸 · Nicolas Rey-Le Lorier🇺🇸 · Yu-Dai Tsai🇺🇸

    We explore the phenomenology of Elastically Decoupling Relic (ELDER) dark matter. ELDER is a thermal relic whose present density is determined primarily by the cross-section of its elastic scattering off Standard Model (SM) particles. Assuming that this scattering is mediated by a kinetically mixed dark photon, we argue that the ELDER scenario makes robust predictions for electron-recoil direct-detection experiments, as well as for dark photon searches. These predictions are independent of the details of interactions within the dark sector. Together with the closely related Strongly-Interacting Massive Particle (SIMP) scenario, the ELDER predictions provide a physically motivated, well-defined target region, which will be almost entirely accessible to the next generation of searches for sub-GeV dark matter and dark photons. We provide useful analytic approximations for various quantities of interest in the ELDER scenario, and discuss two simple renormalizable toy models which incorporate the required strong number-changing interactions among the ELDERs, as well as explicitly implement the coupling to electrons via the dark photon portal.

    hep-phJHEP(2017)·108 citations
12. 12*

    Stochastic and resolvable gravitational waves from ultralight bosons

    Richard Brito🇩🇪 · Shrobana Ghosh🇺🇸 · Enrico Barausse🇫🇷 · Emanuele Berti🇺🇸 · Vitor Cardoso🇵🇹 · Irina Dvorkin🇫🇷 · Antoine Klein🇫🇷 · Paolo Pani🇮🇹

    Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models of massive and stellar-mass black hole populations to compute, for the first time, the stochastic gravitational-wave background from these sources. In optimistic scenarios the background is observable by Advanced LIGO and LISA for field masses $m_s$ in the range $\sim [2\times 10^{-13},10^{-12}]\mathrm{eV}$ and $\sim 5\times [10^{-19},10^{-16}]\mathrm{eV}$, respectively, and it can affect the detectability of resolvable sources. Our estimates suggest that an analysis of the stochastic background limits from LIGO O1 might already be used to marginally exclude axions with mass $\sim 10^{-12.5}\mathrm{eV}$. Semicoherent searches with Advanced LIGO (LISA) should detect $\sim 15(5)$ to $200(40)$ resolvable sources for scalar field masses $3\times 10^{-13}$ ($10^{-17}$) eV. LISA measurements of massive BH spins could either rule out bosons in the range $\sim [10^{-18},2\times 10^{-13}]$ eV, or measure $m_s$ with ten percent accuracy in the range $\sim [10^{-17},10^{-13}]$ eV.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRL(2017)·277 citations
13. 13*

    Black holes in vector-tensor theories

    Lavinia Heisenberg🇨🇭 · Ryotaro Kase🇯🇵 · Masato Minamitsuji🇵🇹 · Shinji Tsujikawa🇯🇵

    We study static and spherically symmetric black hole (BH) solutions in second-order generalized Proca theories with nonminimal vector field derivative couplings to the Ricci scalar, the Einstein tensor, and the double dual Riemann tensor. We find concrete Lagrangians which give rise to exact BH solutions by imposing two conditions of the two identical metric components and the constant norm of the vector field. These exact solutions are described by either Reissner-Nordström (RN), stealth Schwarzschild, or extremal RN solutions with a non-trivial longitudinal mode of the vector field. We then numerically construct BH solutions without imposing these conditions. For cubic and quartic Lagrangians with power-law couplings which encompass vector Galileons as the specific cases, we show the existence of BH solutions with the difference between two non-trivial metric components. The quintic-order power-law couplings do not give rise to non-trivial BH solutions regular throughout the horizon exterior. The sixth-order and intrinsic vector-mode couplings can lead to BH solutions with a secondary hair. For all the solutions, the vector field is regular at least at the future or past horizon. The deviation from General Relativity induced by the Proca hair can be potentially tested by future measurements of gravitational waves in the nonlinear regime of gravity.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2017)·108 citations
14. 14*

    Supersymmetry Breaking in Spatially Modulated Vacua

    Muneto Nitta🇯🇵 · Shin Sasaki🇯🇵 · Ryo Yokokura🇯🇵

    We study spontaneous supersymmetry breaking in spatially modulated stable or meta-stable vacua in supersymmetric field theories. Such spatial modulation can be realized in a higher derivative chiral model for which vacuum energies are either positive, negative or zero, depending on the model parameters. There appears a Nambu-Goldstone boson associated with the spontaneously breaking of the translational and $U(1)$ symmetries without the quadratic kinetic term and with a quartic derivative term in the modulated direction, and a gapless Higgs mode. We show that there appears a Goldstino associated with the supersymmetry breaking at a meta-stable vacuum, where energy is positive, while it becomes a fermionic ghost in the negative energy vacuum, and zero norm state and disappears from the physical sector in the zero energy vacuum.

    ↳ hep-thhep-phPRD(2017)·15 citations
15. 15*

    Order parameters and color-flavor center symmetry in QCD

    Aleksey Cherman🇺🇸 · Srimoyee Sen🇺🇸 · Mithat Unsal🇺🇸 · Michael L. Wagman🇺🇸 · Laurence G. Yaffe🇺🇸

    Common lore suggests that $N$-color QCD with massive quarks has no useful order parameters which can be non-trivial at zero baryon density. However, such order parameters do exist when there are $n_f$ quark flavors with a common mass and $d\equiv \gcd (n_f,N)>1$. These theories have a ${\mathbb{Z}}_d$ color-flavor center symmetry arising from intertwined color center transformations and cyclic flavor permutations. The symmetry realization depends on the temperature, baryon chemical potential and value of $n_f/N$, with implications for conformal window studies and dense quark matter.

    ↳ hep-thhep-lathep-phPRL(2017)·56 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.