Wed·Oct 11, 2017Wednesday·October 11, 2017

1. 01*

   Enhanced pair production of heavy Majorana neutrinos at LHC

   Arindam Das🇰🇷 · Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸

   Towards experimental confirmations of the type-I seesaw mechanism, we explore a prospect of discovering the heavy Majorana right-handed neutrinos (RHNs) from a resonant production of a new massive gauge boson ($Z^{\prime }$) and its subsequent decay into a pair of RHNs ($Z^{\prime }\to NN$) at the future LHC. Recent simulation studies have shown that the discovery of the RHNs through this process is promising in the future. However, the current LHC data very severely constrains the production cross section of the $Z^{\prime }$ boson into a dilepton final states, $pp\to Z^{\prime }\to {\ell }^{+}{\ell }^{-}$ ($\ell =e$ or $\mu$). Extrapolating the current bound to the future, we find that a significant enhancement of the branching ratio $\mathrm{BR}(Z^{\prime }\to NN$) over $\mathrm{BR}(Z^{\prime }\to {\ell }^{+}{\ell }^{-}$) is necessary for the future discovery of RHNs. As a well-motivated simple extension of the Standard Model (SM) to incorporate the $Z^{\prime }$ boson and the type-I seesaw mechanism, we consider the minimal U(1)${}_X$ model. We point out that this model can yield a significant enhancement up to $\mathrm{BR}(Z^{\prime }\to NN)/\mathrm{BR}(Z^{\prime }\to {\ell }^{+}{\ell }^{-})\simeq 5$ (per generation). This is in sharp contrast with the minimal $B-L$ model, a benchmark scenario commonly used in simulation studies, which predicts $\mathrm{BR}(Z^{\prime }\to NN)/\mathrm{BR}(Z^{\prime }\to {\ell }^{+}{\ell }^{-})\simeq 0.5$ (per generation). With such an enhancement and a realistic model-parameter choice to reproduce the neutrino oscillation data, we conclude that the possibility of discovering RHNs with a $300{\mathrm{fb}}^{-1}$ luminosity implies that the $Z^{\prime }$ boson will be discovered with a luminosity of $170.5{\mathrm{fb}}^{-1}$ ($125{\mathrm{fb}}^{-1}$) for the normal (inverted) hierarchy of the light neutrino mass pattern.

   hep-phhep-exPRD(2018)·83 citations
2. 02*

   Analysis of the TeV-scale mirage mediation with heavy superparticles

   Junichiro Kawamura🇯🇵 · Yuji Omura🇯🇵

   We discuss effective models derived from a supersymmetric model whose mediation mechanism of supersymmetry (SUSY) breaking is namely mirage mediation. In this model, light higgsino mass, that is required by the natural realization of the electroweak scale, is achieved by the unification of the soft SUSY breaking parameters at the low scale. Besides, we find that extra Higgs fields are also possibly light in some cases. Then, the effective model is a two Higgs doublet model (2HDM) with higgsinos, and it is distinguishable with namely type-II 2HDM which is widely discussed. In this paper, we study the mass spectrum of SUSY particles and the extra Higgs fields, and summarize the phenomenology in the effective model. We survey the current experimental bounds from the LHC and the dark matter experiments as well as the flavor physics. Then, we point out the expected mass scale of the SUSY particles and reveal the future prospects for the direct and indirect searches. We also discuss the difference between our effective model and the 2HDM in the bottom-up approach.

   hep-phhep-exJHEP(2017)·6 citations
3. 03*

   Transport coefficients from QCD Kondo effect

   Shigehiro Yasui🇯🇵 · Sho Ozaki🇯🇵

   We study the transport coefficients from the QCD Kondo effect in quark matter which contains heavy quarks as impurity particles. We estimate the coupling constant of the interaction between a light quark and a heavy quark at finite density and temperature by using the renormalization group equation up to two-loop order. We also estimate the coupling constant at zero temperature by using the mean-field approximation as non-perturbative treatment. To calculate the transport coefficients, we use the relativistic Boltzmann equation and apply the relaxation time approximation. We calculate the electric resistivity from the relativistic kinetic theory, and the viscosities from the relativistic hydrodynamics. We find that the electric resistivity is enhanced and the shear viscosity is suppressed due to the QCD Kondo effect at low temperature.

   hep-phcond-mat.str-elPRD(2017)·24 citations
4. 04*

   Interaction of the SN1987A Neutrino with the Galaxy

   Kenzo Ishikawa🇯🇵 · Terry Sloan🇬🇧 · Yutaka Tobita🇯🇵

   In previous publications we have shown that long-ignored approximations in standard model calculations could have significant implications for very low mass particles such as neutrinos and photons. In particular we showed that, in a dilute plasma such as that in the solar corona, a significant decay probability of ${\nu }^{\prime }\to \nu +\gamma$ will be possible as a consequence of the terms ignored in making the approximations. Here the ${\nu }^{\prime }$ and $\nu$ are high and low mass eigenstates of the neutrino. In this paper, we investigate the effect in the vicinity of an expanding supernovae remnant such as SN1987A. We show that, in the dilute plasma external to the remnant, such decays are possible and significant. We describe a calculation of effects of such decays on the anti-neutrinos from SN1987A. The calculated anti-neutrino energy against arrival time agrees reasonably well with that observed, assuming that the expansion velocity of the remnant is $\approx 0.2c$ and that the plasma density is high within the expanding remnant.

   hep-ph0 citations
5. 05*

   Medium modification of strange hadronic resonances at SIS, RHIC and LHC energies

   Laura Tolos🇩🇪

   The properties of strange pseudoscalar and vectors mesons as well as strange baryon resonances in dense matter are reviewed. Some open questions on the properties of strange hadrons in medium are addressed, such as the experimental signatures of in-medium effects coming from the hadronic phase on the final observables in heavy-ion collisions for the experimental conditions at SIS, RHIC and LHC energies.

   hep-phnucl-thEPJ Web Conf.(2018)·2 citations
6. 06*

   NNLO predictions for dijet production in diffractive DIS

   Radek Žlebčík🇩🇪 · Daniel Britzger🇩🇪 · Jan Niehues🇨🇭 · Thomas Gehrmann🇨🇭 · James Currie🇬🇧 · Alexander Huss🇨🇭

   Cross sections for inclusive dijet production in diffractive deep-inelastic scattering are calculated for the first time in next-to-next-to-leading order (NNLO) accuracy. These cross sections are compared to several HERA measurements published by the H1 and ZEUS collaborations. We computed the total cross sections, 49 single-differential and five double-differential distributions for six HERA measurements. The NNLO corrections are found to be large and positive. The normalization of the resulting predictions typically exceeds the data, while the kinematical shape of the data is described better at NNLO than at next-to-leading order (NLO). Our results use the currently available NLO diffractive parton distributions, and the discrepancy in normalization highlights the need for a consistent determination of these distributions at NNLO accuracy.

   hep-phPoS(2018)·0 citations
7. 07*

   Spontaneous $CP$ breaking and number of fermionic families

   Gauhar Abbas🇮🇳

   We provide a theoretical justification for the existence of fourth family fermions of the Standard Model by showing that in a novel form of spontaneous $CP$ breaking, fourth family is inevitable. This requires that fermions of third and fourth families must be mirror matter conjectured long back by Lee and Yang.

   hep-ph3 citations
8. 08*

   Dark matter and LHC: Complementarities and limitations

   G. Robbins🇫🇷 · F. Mahmoudi🇫🇷 · A. Arbey🇫🇷 · M. Boudaud🇫🇷

   It is well known that dark matter density measurements, indirect and direct detection experiments, importantly complement the LHC in setting strong constraints on new physics scenarios. Yet, dark matter searches are subject to limitations which need to be considered for realistic analyses. For illustration, we explore the parameter space of the phenomenological MSSM and discuss the interplay of the constraints from dark matter searches and the LHC, and analyse the impact of the astrophysical uncertainties in some detail.

   hep-phastro-ph.HEPoS(2017)·3 citations
9. 09*

   Life of \Pi

   Andreas Maier🇬🇧 · Peter Marquard🇩🇪

   The heavy-quark contribution to the polarisation function $\Pi$ at higher perturbative orders is presently only known approximately. We scrutinise the accuracy of state-of-the-art approximations at three- and four-loop order. At three loops, we present for the first time a result with arbitrary numerical precision for general kinematics and compare to the best Padé estimate. At four loops, we calculate the fourth (inverse) moment of the non-singlet heavy-quark vacuum polarisation in order to test the prediction for this moment based on Padé approximation.

   hep-phPRD(2018)·28 citations
10. 10*

    Probing Leptogenesis at Future Colliders

    Stefan Antusch🇨🇭 · Eros Cazzato🇨🇭 · Marco Drewes🇧🇪 · Oliver Fischer🇩🇪 · Bjorn Garbrecht🇩🇪 · Dario Gueter🇩🇪 · Juraj Klaric🇩🇪

    We investigate the question whether leptogenesis, as a mechanism for explaining the baryon asymmetry of the universe, can be tested at future colliders. Focusing on the minimal scenario of two right-handed neutrinos, we identify the allowed parameter space for successful leptogenesis in the heavy neutrino mass range between $5$ and $50$ GeV. Our calculation includes the lepton flavour violating contribution from heavy neutrino oscillations as well as the lepton number violating contribution from Higgs decays to the baryon asymmetry of the universe. We confront this parameter space region with the discovery potential for heavy neutrinos at future lepton colliders, which can be very sensitive in this mass range via displaced vertex searches. Beyond the discovery of heavy neutrinos, we study the precision at which the flavour-dependent active-sterile mixing angles can be measured. The measurement of these mixing angles at future colliders can test whether a minimal type I seesaw mechanism is the origin of the light neutrino masses, and it can be a first step towards probing leptogenesis as the mechanism of baryogenesis. We discuss how a stronger test could be achieved with an additional measurement of the heavy neutrino mass difference.

    hep-phastro-ph.COhep-exJHEP(2018)·118 citations
11. 11*

    Heavy Higgs Searches: Flavour Matters

    Stefania Gori🇺🇸 · Christophe Grojean🇩🇪 · Aurelio Juste🇪🇸 · Ayan Paul🇮🇹

    We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searches for new heavy Higgs bosons. We propose novel LHC searches that could be performed in the coming years to unravel the existence of these new Higgs bosons.

    hep-phhep-exJHEP(2018)·36 citations
12. 12*

    Dark Matter Freeze-out During Matter Domination

    Saleh Hamdan🇺🇸 · James Unwin🇺🇸

    We highlight the general scenario of dark matter freeze-out whilst the energy density of the universe is dominated by a decoupled non-relativistic species. Decoupling during matter domination changes the freeze-out dynamics, since the Hubble rate is parametrically different for matter and radiation domination. Furthermore, for successful Big Bang Nucleosynthesis the state dominating the early universe energy density must decay, this dilutes (or repopulates) the dark matter. As a result, the masses and couplings required to reproduce the observed dark matter relic density can differ significantly from radiation dominated freeze-out.

    hep-phastro-ph.COMod.Phys.Lett.A(2018)·84 citations
13. 13*

    FlexibleSUSY 2.0: Extensions to investigate the phenomenology of SUSY and non-SUSY models

    Peter Athron🇦🇺 · Markus Bach🇩🇪 · Dylan Harries🇦🇺 · Thomas Kwasnitza🇩🇪 · Jae-hyeon Park🇰🇷 · Dominik Stöckinger🇩🇪 · Alexander Voigt🇩🇪 · Jobst Ziebell🇩🇪

    We document major new features and improvements of FlexibleSUSY, a Mathematica and C++ package with a dependency on the external package SARAH, that generates fast and precise spectrum generators. The extensions presented here significantly increase the generality and capabilities of the FlexibleSUSY package, which already works with a wide class of models, while maintaining an elegant structure and easy to use interfaces. The FlexibleBSM extension makes it possible to also create spectrum generators for non-supersymmetric extensions of the Standard Model. The FlexibleCPV extension adds the option of complex parameters to the spectrum generators, allowing the study of many interesting models with new sources of $CP$ violation. FlexibleMW computes the decay of the muon for the generated model and thereby allows FlexibleSUSY to predict the mass of the $W$ boson from the input parameters by using the more precise electroweak input of $\{G_F,M_Z,{\alpha }_{\text{em}}\}$ instead of $\{M_W,M_Z,{\alpha }_{\text{em}}\}$. The FlexibleAMU extension provides a calculator of the anomalous magnetic moment of the muon in any model FlexibleSUSY can generate a spectrum for. FlexibleSAS introduces a new solver for the boundary value problem which makes use of semi-analytic expressions for dimensionful parameters to find solutions in models where the classic two-scale solver will not work such as the constrained E${}_6$SSM. FlexibleEFTHiggs is a hybrid calculation of the Higgs mass which combines the virtues of both effective field theory calculations and fixed-order calculations. All of these extensions are included in FlexibleSUSY 2.0, which is released simultaneously with this manual.

    hep-phComput.Phys.Commun.(2018)·132 citations
14. 14*

    A viable QCD axion in the MeV mass range

    Daniele S. M. Alves🇺🇸 · Neal Weiner🇺🇸

    The QCD axion is one of the most compelling solutions of the strong CP problem. There are major current efforts into searching for an ultralight, invisible axion, which is believed to be the only phenomenologically viable realization of the QCD axion. Visible axions with decay constants at or below the electroweak scale are believed to have been long excluded by laboratory searches. Considering the significance of the axion solution of the strong CP problem, we revisit experimental constraints on QCD axions in the O(10 MeV) mass window. In particular, we find a variant axion model that remains compatible with existing constraints. This model predicts new states at the GeV scale coupled hadronically, and a variety of low-energy axion signatures, such as rare meson decays, nuclear de-excitations via axion emission, production in $e^{+}{e}^{-}$ annihilation and fixed target experiments. This reopens the possibility of solving the strong CP problem at the GeV scale.

    hep-phhep-exJHEP(2018)·158 citations
15. 15*

    Confinement study of an SU(4) gauge theory with fermions in multiple representations

    Venkitesh Ayyar🇺🇸 · Daniel Hackett🇺🇸 · William Jay🇺🇸 · Ethan Neil🇺🇸

    We discuss the phase diagnostics used in our finite-temperature study of an SU(4) gauge theory with dynamical fermions in both the fundamental and two-index antisymmetric representations. Beyond the usual Polyakov loop diagnostics of confinement, we employ several Wilson flow phase diagnostics. The first, what we call the "flow anisotropy", is known in the literature: the deconfinement transition introduces anisotropy between the spatial and temporal directions, to which the flow is extremely sensitive. The second, the "long flow time Polyakov loop," is related but novel. While we do not claim to fully understand this diagnostic, we have empirically found it to be useful as an unusually sharp diagnostic of phase.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·12 citations
16. 16*

    Search for new physics with the SHiP experiment at CERN

    Oliver Lantwin🇬🇧

    SHiP is a new general purpose fixed target experiment at the CERN SPS designed to complement LHC experiments in the search for new physics. In its initial phase, the $400$ GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating $2\times 10^{20}$ pot in 5 years. Shielded by an active muon shield, a dedicated detector, based on a long decay volume followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived exotic particles with masses below $\mathcal{O}(10)\mathrm{GeV}/c^2$. The main focus will be the physics of the so-called Hidden Portals, i.e. search for Dark Photons, Light scalars and pseudo-scalars, and Heavy Neutral Leptons. The sensitivity to Heavy Neutral Leptons will allow for the first time to probe, in the mass range above the kaon mass, a coupling range for which Baryogenesis and active neutrino masses could also be explained. A dedicated emulsion-based detector will allow detection of light dark matter in an unexplored parameter range.

    ↳ hep-exhep-phPoS(2017)·6 citations
17. 17*

    A direct test of the integral Yang-Mills equations through SU(2) monopoles

    C. P. Constantinidis🇧🇷 · L. A. Ferreira🇧🇷 · G. Luchini🇧🇷

    We use the SU(2) 't Hooft-Polyakov monopole configuration, and its BPS version, to test the integral equations of the Yang-Mills theory. Those integral equations involve two (complex) parameters which do not appear in the differential Yang-Mills equations, and if they are considered to be arbitrary it then implies that non-abelian gauge theories (but not abelian ones) possess an infinity of integral equations. For static monopole configurations only one of those parameters is relevant. We expand the integral Yang-Mills equation in a power series of that parameter and show that the 't Hooft-Polyakov monopole and its BPS version satisfy the integral equations obtained in first and second order of that expansion. Our results points to the importance of exploring the physical consequences of such an infinity of integral equations on the global properties of the Yang-Mills theory.

    ↳ hep-thhep-phmath-phmath.MPPRD(2017)·3 citations
18. 18*

    Atiyah-Patodi-Singer index from the domain-wall fermion Dirac operator

    Hidenori Fukaya🇯🇵 · Tetsuya Onogi🇯🇵 · Satoshi Yamaguchi🇯🇵

    The Atiyah-Patodi-Singer(APS) index theorem attracts attention for understanding physics on the surface of materials in topological phases. The mathematical set-up for this theorem is, however, not directly related to the physical fermion system, as it imposes on the fermion fields a non-local boundary condition known as the "APS boundary condition" by hand, which is unlikely to be realized in the materials. In this work, we attempt to reformulate the APS index in a "physicist-friendly" way for a simple set-up with $U(1)$ or $SU(N)$ gauge group on a flat four-dimensional Euclidean space. We find that the same index as APS is obtained from the domain-wall fermion Dirac operator with a local boundary condition, which is naturally given by the kink structure in the mass term. As the boundary condition does not depend on the gauge fields, our new definition of the index is easy to compute with the standard Fujikawa method.

    ↳ hep-thcond-mat.otherhep-lathep-ph+2PRD(2017)·45 citations
19. 19*

    Fermion number of twisted kinks in the NJL${}_2$ model, revisited

    Michael Thies🇩🇪

    As a consequence of axial current conservation, fermions cannot be localized in the massless NJL${}_2$ model. In the case of twisted kinks, this manifests itself in a cancellation between valence fermion density and fermion density induced in the Dirac sea. To attribute the correct fermion number to these bound states requires an infrared regularization. Recently, this has been achieved by introducing a bare fermion mass, at least in the non-relativistic regime of small twist angles and fermion numbers. Here, we propose a simpler regularization by a finite box which preserves integrability and can be applied at any twist angle. A consistent and physically plausible assignment of fermion number to all twisted kinks emerges.

    ↳ hep-thcond-mat.str-elhep-phPRD(2018)·2 citations
20. 20*

    Measuring the Small-Scale Matter Power Spectrum with High-Resolution CMB Lensing

    Ho Nam Nguyen (1)🇺🇸 · Neelima Sehgal (1)🇺🇸 · Mathew Madhavacheril (2) ((1) Stony Brook University, (2) Princeton University)🇺🇸

    We present a method to measure the small-scale matter power spectrum using high-resolution measurements of the gravitational lensing of the Cosmic Microwave Background (CMB). To determine whether small-scale structure today is suppressed on scales below 10 kiloparsecs (corresponding to M < 10^9 M_sun), one needs to probe CMB-lensing modes out to L ~ 35,000, requiring a CMB experiment with about 20 arcsecond resolution or better. We show that a CMB survey covering 4,000 square degrees of sky, with an instrumental sensitivity of 0.5 uK-arcmin at 18 arcsecond resolution, could distinguish between cold dark matter and an alternative, such as 1 keV warm dark matter or 10^(-22) eV fuzzy dark matter with about 4-sigma significance. A survey of the same resolution with 0.1 uK-arcmin noise could distinguish between cold dark matter and these alternatives at better than 20-sigma significance; such high-significance measurements may also allow one to distinguish between a suppression of power due to either baryonic effects or the particle nature of dark matter, since each impacts the shape of the lensing power spectrum differently. CMB temperature maps yield higher signal-to-noise than polarization maps in this small-scale regime; thus, systematic effects, such as from extragalactic astrophysical foregrounds, need to be carefully considered. However, these systematic concerns can likely be mitigated with known techniques. Next-generation CMB lensing may thus provide a robust and powerful method of measuring the small-scale matter power spectrum.

    ↳ astro-ph.COhep-phPRD(2019)·44 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.