Mon·May 28, 2018Monday·May 28, 2018

1. 01*

   Neutrino and Collider Implications of a Left-Right Extended Zee Model

   Sarif Khan🇮🇳 · Manimala Mitra🇮🇳 · Ayon Patra🇮🇳

   We study a simple left-right symmetric (LRS) extension of the Zee model for neutrino mass generation. An extra $SU(2{)}_{L/R}$ singlet charged scalar helps in generating a loop-induced Majorana mass for neutrinos in this model. The right-handed neutrinos in this case are very light of the order of a few eV to a few MeV which makes this scenario quite different from other LRS models. We have analyzed the scalar potential and Higgs spectrum in detail, which also play an important role for the neutrino phenomenology. We identified the parameter regions in the model which satisfy the experimentally observed neutrino masses and mixings along with other experimental constraints. We have then studied the collider signatures of the charged scalar at $e^{+}{e}^{-}$ colliders with different benchmark points. It is possible to get a huge enhancement in the production cross-section of the charged scalar at lepton collider compared to the hadron colliders, resulting in a much stronger signal which can be easily observed at the upcoming ILC or CLIC experiments.

   hep-phPRD(2018)·4 citations
2. 02*

   MINLO t-channel single-top plus jet

   Stefano Carrazza🇨🇭 · Rikkert Frederix🇩🇪 · Keith Hamilton🇬🇧 · Giulia Zanderighi🇨🇭

   We present a next-to-leading order accurate simulation of t-channel single-top plus jet production matched to parton showers via the POWHEG method. The calculation underlying the simulation is enhanced with a process-specific implementation of the multi-scale improved NLO (MINLO) method, such that it gives physical predictions all through phase space, including regions where the jet additional to the t-channel single-top process is unresolved. We further describe a tuning procedure for the MINLO Sudakov form factor, fitting the coefficient of the first subleading term in its exponent using an artificial neural-network. The latter tuning, implemented as a straightforward event-by-event reweighting, renders the MINLO simulation NLO accurate for t-channel single-top observables, in addition to those of the analogous single-top plus jet process.

   hep-phJHEP(2018)·18 citations
3. 03*

   NNLOPS accurate predictions for $W^{+}{W}^{-}$ production

   Emanuele Re🇨🇭 · Marius Wiesemann🇨🇭 · Giulia Zanderighi🇨🇭

   We present novel predictions for the production of $W^{+}{W}^{-}$ pairs in hadron collisions that are next-to-next-to-leading order accurate and consistently matched to a parton shower (NNLOPS). All diagrams that lead to the process $pp\to e^{-}{\bar{\nu }}_e{\mu }^{+}{\nu }_{\mu }+X$ are taken into account, thereby including spin correlations and off-shell effects. For the first time full NNLOPS accuracy is achieved for a $2\to 4$ process. We find good agreement, at the 1$\sigma$ level, with the $W^{+}{W}^{-}$ rates measured by ATLAS and CMS. The importance of NNLOPS predictions is evident from differential distributions sensitive to soft-gluon effects and from the large impact ($10$% and more) of including next-to-next-to-leading order corrections on top of MiNLO. We define a charge asymmetry for the $W$ bosons and the leptons in $W^{+}{W}^{-}$ production at the LHC, which is sensitive to the $W$ polarizations and hence can be used as a probe of new physics.

   hep-phhep-exJHEP(2018)·78 citations
4. 04*

   $B-L$ as a Gauged Peccei-Quinn Symmetry

   Masahiro Ibe🇯🇵 · Motoo Suzuki🇯🇵 · Tsutomu T. Yanagida🇯🇵

   The gauged Peccei-Quinn (PQ) mechanism provides a simple prescription to embed the global PQ symmetry into a gauged $U(1)$ symmetry. As it originates from the gauged PQ symmetry, the global PQ symmetry can be protected from explicit breaking by quantum gravitational effects once appropriate charge assignment is given. In this paper, we identify the gauged PQ symmetry with the $B-L$ symmetry, which is obviously attractive as the $B-L$ gauge symmetry is the most authentic extension of the Standard Model. As we will show, a natural $B-L$ charge assignment can be found in a model motivated by the seesaw mechanism in the $SU(5)$ Grand Unified Theory. As a notable feature of this model, it does not require extra $SU(5)$ singlet matter fields other than the right-handed neutrinos to cancel the self and the gravitational anomalies.

   hep-phJHEP(2018)·30 citations
5. 05*

   Importance of generalized $\mu \tau$ symmetry and its CP extension on neutrino mixing and leptogenesis

   Rome Samanta🇬🇧 · Roopam Sinha🇮🇳 · Ambar Ghosal🇮🇳

   Within the framework of residual symmetry, two ${\mathbb{Z}}_2$ type associate $\mu \tau$ interchange symmetries robustly constrain the Dirac CP phase $\delta$ in a model independent way. Both of them predict simultaneous maximality of $\delta$ and the atmospheric mixing angle ${\theta }_{23}$. We show how these well known correlations will be changed if we generalize the $\mu \tau$ interchange symmetry to a $\mu \tau$ mixing symmetry. In particular, we show that the stringent condition of simultaneous maximality could be relaxed even with a very small departure from the exact $\mu \tau$ interchange. In addition, the present neutrino data on $\delta$ and ${\theta }_{23}$ can be explained better by the mixing symmetry. After discussing the impact of the $\mu \tau$ mixing in some realistic neutrino mass models, we show how the proposed mixing could be realized with two simultaneous CP transformations which also lead to novel and testable correlations between $\delta$ and the mixing angles ${\theta }_{ij}$. Next we discuss in particular, the `three flavour regime' of leptogenesis within the CP extended framework and show, unlike the ordinary CP extended $\mu \tau$ interchange symmetry, a resonant leptogenesis is possible due the generalization of $\mu \tau$ interchange to the $\mu \tau$ mixing and the resulting baryon asymmetry always requires a nonmaximal ${\theta }_{23}$ owing to the fact that the baryon to photon ratio ${\eta }_B$ vanishes in the exact limit of ${\theta }_{23}=\pi /4$. This is one of the robust predictions of this framework. The CP extended $\mu \tau$ mixing is also a novel example of a low energy effective model that provides an important insight to the off-diagonal terms of the flavour coupling matrix which have usually been neglected in literature to compute the final baryon asymmetry, in particular in the models with flavour symmetries.

   hep-phJHEP(2019)·15 citations
6. 06*

   Probing the Higgs boson-gluon coupling via the jet energy profile at $e^{+}{e}^{-}$ colliders

   Gexing Li🇨🇳 · Zhao Li🇨🇳 · Yandong Liu🇨🇳 · Yan Wang🇨🇳 · Xiaoran Zhao🇧🇪

   The effective coupling of the Higgs boson to a gluon pair is one of the most important parameters to test the Standard Model and search for the new physics beyond. In this paper, we propose several new observables based on the jet energy profile to extract the effective coupling. The statistical uncertainties of the effective coupling extracted by using new observables are derived and estimated based on the simulation at the future $e^{+}{e}^{-}$ collider for $250$ GeV center-of-mass energy and 5 ab${}^{-1}$ integrated luminosity. We found that the statistical uncertainties of effective coupling via the optimized observable can reach about $1.6\%$ in the channels of a $Z$ boson decaying to lepton pairs and is reduced by $52\%$ compared to the relevant uncertainties in the conventional approach. These new observables potentially can be helpful for the measurement of effective coupling at future $e^{+}{e}^{-}$ colliders.

   hep-phPRD(2018)·6 citations
7. 07*

   Radiative corrections to vectorlike portal dark matter

   Stefano Colucci🇩🇪 · Federica Giacchino🇧🇪 · Michel H.G. Tytgat🇧🇪 · Jérôme Vandecasteele🇧🇪

   A massive real scalar dark matter particle $S$ can couple to Standard Model leptons or quarks through a vector-like fermionic mediator $\psi$, a scenario known as the Vector-like portal. Due to helicity suppression of the annihilation cross section into a pair of SM fermions, it has been shown in previous works that radiative corrections, either at one-loop or through radiation of gauge bosons, may play a significant role both in determining the relic abundance and for indirect detection. All previous works considered the limit of massless final state quarks or leptons. In this work, we focus on a technical issue, which is to reliably determine the annihilation cross sections taking into account finite fermion masses. Following previous works in the framework of simplified supersymmetric dark matter scenarios, and building on an analogy with Higgs decay into fermions, we address the issue of infrared and collinear divergences that plagues the cross section by adopting an effective operator description, which captures most of the relevant physics and give explicit expressions for the annihilation cross sections. We then develop several approximations for the differential and total cross sections, which simplify greatly their expressions, and which can then be used in various phenomenological studies of similar models. Finally, we describe our method to compute the final gamma-ray spectrum, including hadronisation of the heavy fermions, and provide some illustrative spectra for specific dark matter candidates.

   hep-phPRD(2018)·20 citations
8. 08*

   Understanding the degeneracies in NO$\nu$A data

   Suman Bharti🇮🇳 · Suprabh Prakash🇧🇷 · Ushak Rahaman🇮🇳 · S. Uma Sankar🇮🇳

   The combined analysis of ${\nu }_{\mu }$ disappearance and ${\nu }_e$ appearance data of NO$\nu$A experiment leads to three nearly degenerate solutions. This degeneracy can be understood in terms of deviations in ${\nu }_e$ appearance signal, caused by unknown effects, with respect to the signal expected for a reference set of oscillations parameters. We define the reference set to be vacuum oscillations in the limit of maximal ${\theta }_{23}$ and no CP-violation. We then calculate the deviations induced in the ${\nu }_e$ appearance signal event rate by three unknown effects: (a) matter effects, due to normal or inverted hierarchy (b) octant effects, due to ${\theta }_{23}$ being in higher or lower octant and (c) CP-violation, whether ${\delta }_{CP}\sim -\pi /2$ or ${\delta }_{CP}\sim \pi /2$. We find that the deviation caused by each of these effects is the same for NO$\nu$A. The observed number of ${\nu }_e$ events in NO$\nu$A is equivalent to the increase caused by one of the effects. Therefore, the observed number of ${\nu }_e$ appearance events of NO$\nu$A is the net result of the increase caused by two of the unknown effects and the decrease caused by the third. Thus we get the three degenerate solutions. We also find that further data by NO$\nu$A can not distinguish between these degenerate solutions but addition of one year of neutrino run of DUNE can make a distinction between all three solutions. The distinction between the two NH solutions and the IH solution becomes possible because of the larger matter effect in DUNE. The distinction between the two NH solutions with different octants is a result of the synergy between the anti-neutrino data of NO$\nu$A and the neutrino data of DUNE.

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

   Shining Light on the Mass Scale and Nature of Neutrinos with $e\gamma \to e\nu \overline{\nu }$

   Jeffrey M. Berryman🇺🇸 · André de Gouvêa🇺🇸 · Kevin J. Kelly🇺🇸 · Michael Schmitt🇺🇸

   The discovery of neutrino oscillations invites many fundamental physics questions that have yet to be answered. Two of these questions are simple, easy to state, and essential: What are the values of the neutrino masses? Are neutrinos Majorana fermions? The reason we don't know the answer to those questions is that it is difficult to measure neutrino properties outside of the ultrarelativistic regime. We discuss the physics of $e\gamma \to e\nu \bar{\nu }$ near threshold, where one has access to nonrelativistic neutrinos and only nonrelativistic neutrinos. Near threshold, $e\gamma \to e\nu \bar{\nu }$ is a rich phenomenon and its cross section is sensitive to the individual values of the neutrino masses and the nature of the neutrinos. We show that if one could scan the threshold region, it would be simple to identify the mass of the lightest neutrino, the neutrino mass ordering, and whether the neutrinos are Majorana fermions. In practice, however, event rates are tiny and backgrounds are huge; the observation of $e\gamma \to e\nu \bar{\nu }$ in the sub-eV regime appears to be utterly inaccessible in the laboratory. Our results, nonetheless, effectively illustrate the discriminatory power of nonrelativistic neutrino observables.

   hep-phPRD(2018)·16 citations
10. 10*

    Digital quantum computation of fermion-boson interacting systems

    Alexandru Macridin🇺🇸 · Panagiotis Spentzouris🇺🇸 · James Amundson🇺🇸 · Roni Harnik🇺🇸

    We introduce a new method for representing the low energy subspace of a bosonic field theory on the qubit space of digital quantum computers. This discretization leads to an exponentially precise description of the subspace of the continuous theory thanks to the Nyquist-Shannon sampling theorem. The method makes the implementation of quantum algorithms for purely bosonic systems as well as fermion-boson interacting systems feasible. We present algorithmic circuits for computing the time evolution of these systems. The complexity of the algorithms scales polynomially with the system size. The algorithm is a natural extension of the existing quantum algorithms for simulating fermion systems in quantum chemistry and condensed matter physics to systems involving bosons and fermion-boson interactions and has a broad variety of potential applications in particle physics, condensed matter, etc. Due to the relatively small amount of additional resources required by the inclusion of bosons in our algorithm, the simulation of electron-phonon and similar systems can be placed in the same near-future reach as the simulation of interacting electron systems. We benchmark our algorithm by implementing it for a $2$-site Holstein polaron problem on an Atos Quantum Learning Machine (QLM) quantum simulator. The polaron quantum simulations are in excellent agreement with the results obtained by exact diagonalization.

    ↳ quant-phcond-mat.str-elhep-phPRA(2018)·119 citations
11. 11*

    Universal aspects of the phase diagram of QCD with heavy quarks

    Jan Maelger🇫🇷 · Urko Reinosa🇫🇷 · Julien Serreau🇫🇷

    The flavor dependence of the QCD phase diagram presents universal properties in the heavy quark limit. For the wide class of models where the quarks are treated at the one-loop level, we show, for arbitrary chemical potential, that the flavor dependence of the critical quark masses-for which the confinement-deconfinement transition is second order-is insensitive to the details of the (confining) gluon dynamics and that the critical temperature is constant along the corresponding critical line. We illustrate this with explicit results in various such one-loop models studied in the literature: effective matrix models for the Polyakov loop, the Curci-Ferrari model, and a recently proposed Gribov-Zwanziger-type model. We further observe that the predictions which follow from this one-loop universality property are well satisfied by different calculations beyond one-loop order, including lattice simulations. For degenerate quarks, we propose a simple universal law for the flavor dependence of the critical mass, satisfied by all approaches.

    ↳ hep-thhep-phnucl-thPRD(2018)·35 citations
12. 12*

    On the Baker-Campbell-Hausdorff Theorem: non-convergence and prolongation issues

    Stefano Biagi🇮🇹 · Andrea Bonfiglioli🇮🇹 · Marco Matone🇮🇹

    We investigate some topics related to the celebrated Baker-Campbell-Hausdorff Theorem: a non-convergence result and prolongation issues. Given a Banach algebra $\mathcal{A}$ with identity $I$, and given $X,Y\in \mathcal{A}$, we study the relationship of different issues: the convergence of the BCH series ${\sum }_n{Z}_n(X,Y)$, the existence of a logarithm of $e^X{e}^Y$, and the convergence of the Mercator-type series ${\sum }_n(-1{)}^{n+1}(e^X{e}^Y-I{)}^n/n$ which provides a selected logarithm of $e^X{e}^Y$. We fix general results and, by suitable matrix counterexamples, we show that various pathologies can occur, among which we provide a non-convergence result for the BCH series. This problem is related to some recent results, of interest in physics, on closed formulas for the BCH series: while the sum of the BCH series presents several non-convergence issues, these closed formulas can provide a prolongation for the BCH series when it is not convergent. On the other hand, we show by suitable counterexamples that an analytic prolongation of the BCH series can be singular even if the BCH series itself is convergent.

    ↳ math-phcond-mat.stat-mechhep-phhep-th+2Linear Multilinear Alg.(2018)·17 citations
13. 13*

    Constraints on long-lived, higher-spin particles from galaxy bispectrum

    Azadeh Moradinezhad Dizgah🇺🇸 · Gabriele Franciolini🇨🇭 · Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭

    The presence of massive particles with spin during inflation induces distinct signatures on correlation functions of primordial curvature fluctuations. In particular, the bispectrum of primordial perturbations obtains an angular dependence determined by the spin of the particle, which can be used to set constraints on the presence of such particles. If these particles are long-lived on super-Hubble scales, as is the case for example for partially massless particles, their imprint on correlation functions of curvature perturbations would be unsuppressed. In this paper, we make a forecast for how well such angular dependence can be constrained by the upcoming EUCLID spectroscopic survey via the measurement of galaxy bispectrum.

    ↳ astro-ph.COhep-phhep-thPRD(2018)·29 citations
14. 14*

    Hunting for Axionlike Dark Matter by Searching for an Oscillating Neutron Electric Dipole Moment

    N. J. Ayres🇬🇧

    We report on a search for ultra-low-mass axion-like dark matter by analysing the ratio of the spin-precession frequencies of stored ultracold neutrons and ${}^{199}$Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range $10^{-24}\text{eV}\le m_a\le 10^{-17}\text{eV}$. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40. The results were initially presented in Phys. Rev. X 7, 041034, of which this proceeding is largely a summary.

    ↳ hep-exhep-ph2 citations
15. 15*

    Rationalizing Loop Integration

    Jacob L. Bourjaily🇩🇰 · Andrew J. McLeod🇩🇰 · Matt von Hippel🇩🇰 · Matthias Wilhelm🇩🇰

    We show that direct Feynman-parametric loop integration is possible for a large class of planar multi-loop integrals. Much of this follows from the existence of manifestly dual-conformal Feynman-parametric representations of planar loop integrals, and the fact that many of the algebraic roots associated with (e.g. Landau) leading singularities are automatically rationalized in momentum-twistor space---facilitating direct integration via partial fractioning. We describe how momentum twistors may be chosen non-redundantly to parameterize particular integrals, and how strategic choices of coordinates can be used to expose kinematic limits of interest. We illustrate the power of these ideas with many concrete cases studied through four loops and involving as many as eight particles. Detailed examples are included as ancillary files to this work's submission to the arXiv.

    ↳ hep-thhep-phJHEP(2018)·71 citations
16. 16*

    Kinetic freeze out conditions in nuclear collisions with $2A$ - $158A$ GeV beam energy within a non-boost-invariant blast-wave model

    Sudhir Pandurang Rode🇮🇳 · Partha Pratim Bhaduri🇮🇳 · Amaresh Jaiswal🇮🇳 · Ankhi Roy🇮🇳

    We study the kinetic freeze out conditions of bulk hadrons in nuclear collisions. The transverse and longitudinal momentum spectra of the identified hadrons produced in central Au+Au and Pb+Pb collisions, in the beam energy range of $E_b=2A-158A$ GeV are analysed for this purpose, within a generalised non boost-invariant blast wave model. The kinetic freeze out temperature is found to vary in the range of 55 - 90 MeV, whereas the average transverse velocity of collective expansion is found to be around $0.5c$ to $0.6c$. The mean longitudinal velocity of the fireball is seen to increase monotonically with increasing longitudinal boost. The results would be useful to understand the gross collision dynamics for the upcoming experiments at the FAIR and NICA accelerator facilities.

    ↳ nucl-thhep-phPRC(2018)·17 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.