Fri·Apr 22, 2016Friday·April 22, 2016

1. 01*

   Stationary configurations of the Standard Model Higgs potential: electroweak stability and rising inflection point

   Giuseppe Iacobellis🇮🇹 · Isabella Masina🇮🇹

   We study the gauge-independent observables associated with two interesting stationary configurations of the Standard Model Higgs potential (extrapolated to high energy according to the present state of the art, namely the NNLO): i) the value of the top mass ensuring stability of the SM electroweak minimum, and ii) the value of the Higgs potential at a rising inflection point. We examine in detail and reappraise the experimental and theoretical uncertainties which plague their determination, finding that: i) stability of the SM is compatible with the present data at the 1.5 sigma level; ii) despite the large theoretical error plaguing the value of the Higgs potential at a rising inflection point, application of such configuration to models of primordial inflation displays a 3 sigma tension with the recent bounds on the tensor-to-scalar ratio of cosmological perturbations.

   hep-phastro-ph.COPRD(2016)·38 citations
2. 02*

   Angular observables for spin discrimination in boosted diboson final states

   Malte Buschmann🇩🇪 · Felix Yu🇩🇪

   We investigate the prospects for spin determination of a heavy diboson resonance using angular observables. Focusing in particular on boosted fully hadronic final states, we detail both the differences in signal efficiencies and distortions of differential distributions resulting from various jet substructure techniques. We treat the 2 TeV diboson excess as a case study, but our results are generally applicable to any future discovery in the diboson channel. Scrutinizing ATLAS and CMS analyses at 8 TeV and 13 TeV, we find that the specific cuts employed in these analyses have a tremendous impact on the discrimination power between different signal hypotheses. We discuss modified cuts that can offer a significant boost to spin sensitivity in a post-discovery era. Even without altered cuts, we show that CMS, and partly also ATLAS, will be able to distinguish between spin 0, 1, or 2 new physics diboson resonances at the $2\sigma$ level with 30 fb${}^{-1}$ of 13 TeV data, for our 2 TeV case study.

   hep-phJHEP(2016)·3 citations
3. 03*

   Shedding Light on Neutrino Masses with Dark Forces

   Brian Batell🇺🇸 · Maxim Pospelov🇨🇦 · Brian Shuve🇺🇸

   Heavy right-handed neutrinos (RHNs) provide the simplest explanation for the origin of light neutrino masses and mixings. If the RHN masses are at or below the weak scale, direct experimental discovery of these states is possible at accelerator experiments such as the LHC or new dedicated beam dump experiments; in such experiments, the RHN decays after traversing a macroscopic distance from the collision point. The experimental sensitivity to RHNs is significantly enhanced if there is a new "dark" gauge force connecting them to the Standard Model (SM), and detection of RHNs can be the primary discovery mode for the new dark force itself. We take the well-motivated example of a B-L gauge symmetry and analyze the sensitivity to displaced decays of the RHNs produced via the new gauge interaction in two experiments: the LHC and the proposed SHiP beam dump experiment. In the most favorable case in which the mediator can be produced on-shell and decays to RHNs, the sensitivity reach is controlled by the square of the B-L gauge coupling. We demonstrate that these experiments could access neutrino parameters responsible for the observed SM neutrino masses and mixings in the most straightforward implementation of the see-saw mechanism.

   hep-phhep-exJHEP(2016)·104 citations
4. 04*

   Mixed Dark Matter in Left-Right Symmetric Models

   Asher Berlin🇺🇸 · Patrick J. Fox🇺🇸 · Dan Hooper🇺🇸 · Gopolang Mohlabeng🇺🇸

   Motivated by the recently reported diboson and dijet excesses in Run 1 data at ATLAS and CMS, we explore models of mixed dark matter in left-right symmetric theories. In this study, we calculate the relic abundance and the elastic scattering cross section with nuclei for a number of dark matter candidates that appear within the fermionic multiplets of left-right symmetric models. In contrast to the case of pure multiplets, WIMP-nucleon scattering proceeds at tree-level, and hence the projected reach of future direct detection experiments such as LUX-ZEPLIN and XENON1T will cover large regions of parameter space for TeV-scale thermal dark matter. Decays of the heavy charged W' boson to particles in the dark sector can potentially shift the right-handed gauge coupling to larger values when fixed to the rate of the Run 1 excesses, moving towards the theoretically attractive scenario, gR = gL. This region of parameter space may be probed by future collider searches for new Higgs bosons or electroweak fermions.

   hep-phastro-ph.COJCAP(2016)·26 citations
5. 05*

   Production of Neutral and Doubly Charged Partners of D_{s0}^+(2317) Revisited

   Kunihiko Terasaki🇯🇵

   Rates for productions of neutral and doubly charged partners of D_{s0}^+(2317) in B meson decays are studied by using a hard D meson approximation in the infinite momentum frame, and the results are of the same order of magnitude as that of D_{s0}^+(2317). Because the bottom-strange X^{+-}(5568) which can be interpreted as iso-triplet bottom partners of D_{s0}^+(2317) have recently been discovered, observations of neutral and doubly charged partners of D_{s0}^+(2317) are strongly desired.

   hep-ph6 citations
6. 06*

   Explaining the 750 GeV diphoton excess with a colored scalar charged under a new confining gauge interaction

   Robert Foot🇦🇺 · John Gargalionis🇦🇺

   We consider a charged scalar particle $\chi$ of mass around 375 GeV charged under both $SU(3{)}_c$ and a new confining non-abelian gauge interaction. After pair production, these interactions confine the exotic scalar into non-relativistic bound states whose decays into photons can explain the 750 GeV diphoton excess observed at the LHC. Taking the new confining group to be $\mathrm{SU}(2)$, we find $\chi$ must carry an electric charge of $Q\sim [\frac{1}{2},1]$ to fit the data. Interestingly, we find that pair production of the scalars and the subsequent formation of the bound state dominates over direct bound state resonance production. This explanation is quite weakly constrained by current searches and data from the forthcoming run at the LHC will be able to probe our scenario more fully. In particular dijet, mono-jet, di-Higgs and jet + photon searches may be the most promising discovery channels.

   hep-phPRD(2016)·10 citations
7. 07*

   The Dual Standard Model and the 750 GeV Events at the LHC

   Xavier Calmet🇬🇧

   The aim of this short paper is to discuss the recently observed excess at 750 GeV by both CMS and ATLAS in the light of the dual standard model. Within this framework it is natural to introduce neutral spin 0 and/or spin 2 $SU(2)$ glue mesons which could easily account for this observation if it is confirmed. The model predicts that these glue mesons would be part of $SU(2)$ triplets and that there must thus be charged counterparts of these glue mesons carrying a QED charge of $\pm 1$ with a spin 0 and/or 2 as well.

   hep-phEPL(2016)·4 citations
8. 08*

   Determination of the QCD $\Lambda$-parameter and the accuracy of perturbation theory at high energies

   Mattia Dalla Brida🇩🇪 · Patrick Fritzsch🇪🇸 · Tomasz Korzec🇩🇪 · Alberto Ramos🇨🇭 · Stefan Sint🇮🇪 · Rainer Sommer🇩🇪

   We discuss the determination of the strong coupling ${\alpha }_{\overline{\mathrm{MS}}}^{}(m_{\mathrm{Z}})$ or equivalently the QCD $\Lambda$-parameter. Its determination requires the use of perturbation theory in ${\alpha }_s(\mu )$ in some scheme, $s$, and at some energy scale $\mu$. The higher the scale $\mu$ the more accurate perturbation theory becomes, owing to asymptotic freedom. As one step in our computation of the $\Lambda$-parameter in three-flavor QCD, we perform lattice computations in a scheme which allows us to non-perturbatively reach very high energies, corresponding to ${\alpha }_s=0.1$ and below. We find that (continuum) perturbation theory is very accurate there, yielding a three percent error in the $\Lambda$-parameter, while data around ${\alpha }_s\approx 0.2$ is clearly insufficient to quote such a precision. It is important to realize that these findings are expected to be generic, as our scheme has advantageous properties regarding the applicability of perturbation theory.

   hep-phhep-latPRL(2016)·74 citations
9. 09*

   Evidence for creation of strong electromagnetic fields in relativistic heavy-ion collisions

   V. Toneev🇷🇺 · O. Rogachevsky🇷🇺 · V. Voronyuk🇷🇺

   It is proposed to identify a strong electric field created during relativistic collisions of asymmetric nuclei via observation of pseudorapidity and transverse momentum distributions of hadrons with the same mass but opposite charges. The detailed calculation results for the directed flow within the Parton-Hadron String Dynamics model are given for Cu-Au interactions at the NICA collision energies of $\sqrt{s_{NN}}=9$ and $5$ GeV. The separation effect is observable at 9 GeV as clearly as at 200 GeV

   hep-phnucl-thEPJA(2016)·23 citations
10. 10*

    Updated galactic radio constraints on Dark Matter

    Marco Cirelli🇫🇷 · Marco Taoso🇪🇸

    We perform a detailed analysis of the synchrotron signals produced by Dark Matter annihilations and decays. We consider different set-ups for the propagation of electrons and positrons, the galactic magnetic field and Dark Matter properties. We then confront these signals with radio and microwave maps, including Planck measurements, from a frequency of 22 MHz up to 70 GHz. We derive two sets of constraints: conservative and progressive, the latter based on a modeling of the astrophysical emission. Radio and microwave constraints are complementary to those obtained with other indirect detection methods, especially for dark matter annihilating into leptonic channels.

    hep-phastro-ph.COJCAP(2016)·24 citations
11. 11*

    Inverse Magnetic Catalysis in Bottom-Up Holographic QCD

    Nick Evans🇬🇧 · Carlisson Miller🇧🇷 · Marc Scott🇬🇧

    We explore the effect of magnetic field on chiral condensation in QCD via a simple bottom up holographic model which inputs QCD dynamics through the running of the anomalous dimension of the quark bilinear. Bottom up holography is a form of effective field theory and we use it to explore the dependence on the coefficients of the two lowest order terms linking the magnetic field and the quark condensate. In the massless theory, we identify a region of parameter space where magnetic catalysis occurs at zero temperature but inverse magnetic catalysis at temperatures of order the thermal phase transition. The model shows similar non-monotonic behaviour in the condensate with B at intermediate T as the lattice data. This behaviour is due to the separation of the meson melting and chiral transitions in the holographic framework. The introduction of quark mass raises the scale of B where inverse catalysis takes over from catalysis until the inverse catalysis lies outside the regime of validity of the effective description leaving just catalysis.

    hep-phPRD(2016)·53 citations
12. 12*

    Probing Non-holomorphic MSSM via precision constraints, dark matter and LHC data

    Utpal Chattopadhyay (IACS, Kolkata)🇮🇳 · Abhishek Dey (Maulana Azad College, Kolkata)🇮🇳

    In this analysis we explore the phenomenological constraints of models with non-holomorphic soft SUSY breaking terms in a beyond the MSSM scenario having identical particle content. The model referred as NHSSM shows various promising features like the possibility of a strong reduction in electroweak fine-tuning even for a scenario of a heavy higgsino type of LSP, a fact that is unavailable in pMSSM models. The other important aspect is satisfying the muon $g-2$ data even for a small $\tan \beta$ via a small value of coupling $A_{\mu }^{\prime }$ associated with the tri-linear non-holomorphic soft term. Thus, a large SUSY contribution to muon $g-2$ is possible even for a significantly large smuon mass $m_{\widetilde{{\mu }_1}}$. The Higgs mass radiative corrections are contributed by both the holomorphic and non-holomorphic trilinear soft parameters $A_t$ and $A_t^{\prime }$, thus diluting the requirement to have a larger $A_t$ to satisfy the Higgs mass data. The model also provides with valid parameter space satisfying the constraint of $B\to X_s+\gamma$ for large values of $\tan \beta$, a scenario unfavourable in pMSSM.

    hep-phJHEP(2016)·25 citations
13. 13*

    Systematic estimation of theoretical uncertainties in the calculation of the pion-photon transition form factor using light-cone sum rules

    S. V. Mikhailov🇷🇺 · A. V. Pimikov🇨🇳 · N. G. Stefanis🇩🇪

    We consider the calculation of the pion-photon transition form factor $F^{{\gamma }^{\ast }\gamma {\pi }^0}(Q^2)$ within light-cone sum rules focusing attention to the low-mid region of momenta. The central aim is to estimate the theoretical uncertainties which originate from a wide variety of sources related to (i) the relevance of next-to-next-to-leading order radiative corrections (ii) the influence of the twist-four and the twist-six term (iii) the sensitivity of the results on auxiliary parameters, like the Borel scale $M^2$, (iv) the role of the phenomenological description of resonances, and (v) the significance of a small but finite virtuality of the quasireal photon. Predictions for $F^{{\gamma }^{\ast }\gamma {\pi }^0}(Q^2)$ are presented which include all these uncertainties and found to comply within the margin of experimental error with the existing data in the $Q^2$ range between 1 and 5 GeV${}^2$, thus justifying the reliability of the applied calculational scheme. This provides a solid basis for confronting theoretical predictions with forthcoming data bearing small statistical errors.

    hep-phPRD(2016)·49 citations
14. 14*

    Is the observability of sterile neutrino masses consistent with $\nu -$oscillations?

    R. Ehrlich🇺🇸

    It is shown that a 1980 proposal to search for heavy sterile neutrinos by observing the energy of the associated lepton in weak decays rests on an questionable assumption, and that the possibility of such a detection might be inconsistent with the observability of neutrino oscillations.

    hep-ph0 citations
15. 15*

    Magnon Inflation: Slow Roll with Steep Potentials

    Peter Adshead🇺🇸 · Diego Blas🇨🇭 · C.P. Burgess🇨🇦 · Peter Hayman🇨🇦 · Subodh P Patil🇨🇭

    We find multi-scalar effective field theories (EFTs) that can achieve a slow inflationary roll despite having a scalar potential that does not satisfy the usual slow-roll condition (d V)^2 << V^2/Mp^2. They evade the usual slow-roll conditions on $V$ because their kinetic energies are dominated by single-derivative terms rather than the usual two-derivative terms. Single derivatives dominate during slow roll and so do not require a breakdown of the usual derivative expansion that underpins calculational control in much of cosmology. The presence of such terms requires some sort of UV Lorentz-symmetry breaking during inflation (besides the usual cosmological breaking). Chromo-natural inflation provides an example of a UV theory that can generate the multi-field single-derivative terms we consider, and we argue that the EFT we find indeed captures the slow-roll conditions for the background evolution for Chromo-natural inflation. We also show that our EFT can be understood as a multi-field generalization of the single-field Cuscuton models. The multi-field case introduces a new feature, however: the scalar kinetic terms define a target-space 2-form, F_{ab}, whose antisymmetry gives new ways for slow roll to be achieved.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2016)·17 citations
16. 16*

    Radiative Screening of Fifth Forces

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

    We describe a symmetron model in which the screening of fifth forces arises at the one-loop level through the Coleman-Weinberg mechanism of spontaneous symmetry breaking. We show that such a theory can avoid current constraints on the existence of fifth forces but still has the potential to give rise to observable deviations from general relativity, which could be seen in cold atom experiments.

    ↳ gr-qcastro-ph.COhep-phhep-thPRL(2016)·36 citations
17. 17*

    Precision decay rate calculations in quantum field theory

    Anders Andreassen🇺🇸 · David Farhi🇺🇸 · William Frost🇺🇸 · Matthew D. Schwartz🇺🇸

    Tunneling in quantum field theory is worth understanding properly, not least because it controls the long term fate of our universe. There are however, a number of features of tunneling rate calculations which lack a desirable transparency, such as the necessity of analytic continuation, the appropriateness of using an effective instead of classical potential, and the sensitivity to short-distance physics. This paper attempts to review in pedagogical detail the physical origin of tunneling and its connection to the path integral. Both the traditional potential-deformation method and a recent more direct propagator-based method are discussed. Some new insights from using approximate semi-classical solutions are presented. In addition, we explore the sensitivity of the lifetime of our universe to short distance physics, such as quantum gravity, emphasizing a number of important subtleties.

    ↳ hep-thhep-phPRD(2017)·152 citations
18. 18*

    Chiral Lagrangian from Duality and Monopole Operators in Compactified QCD

    Aleksey Cherman🇺🇸 · Thomas Schaefer🇺🇸 · Mithat Unsal🇺🇸

    We show that there exists a special compactification of QCD on ${\mathbb{R}}^3\times S^1$ in which the theory has a domain where continuous chiral symmetry breaking is analytically calculable. We give a microscopic derivation of the chiral lagrangian, the chiral condensate, and the Gell-Mann-Oakes-Renner relation $m_{\pi }^2{f}_{\pi }^2=m_q⟨\bar{q}q⟩$. Abelian duality, monopole operators, and flavor-twisted boundary conditions, or a background flavor holonomy, play the main roles. The flavor twisting leads to the new effect of fractional jumping of fermion zero modes among monopole-instantons. Chiral symmetry breaking is induced by monopole-instanton operators, and the Nambu-Goldstone pions arise by color-flavor transmutation from gapless "dual photons". We also give a microscopic picture of the "constituent quark" masses. Our results are consistent with expectations from chiral perturbation theory at large $S^1$, and yield strong support for adiabatic continuity between the small-$S^1$ and large-$S^1$ regimes. We also find concrete microscopic connections between $\mathcal{N}=1$ and $\mathcal{N}=2$ supersymmetric gauge theory dynamics and non-supersymmetric QCD dynamics.

    ↳ hep-thhep-lathep-phPRL(2016)·53 citations
19. 19*

    Hunt for Sterile Neutrinos: Decay at Rest Experiments

    Fumihiko Suekane🇯🇵

    In the standard model of the elementary particles, the number of neutrino flavor is three. However, there have been indications of existence of 4th neutrino, called sterile neutrino, in some neutrino oscillation related experiments. A number of experiments are planned to test whether such indications are true or not. Among them, experiments which use neutrinos from pi+, K+, mu+ decay at rest (DAR) are promising because the energy spectra of neutrinos are very well known and clean oscillation measurements are possible. In this proceedings, properties of such DAR neutrinos and LSND, JSNS2, OscSNS and KPipe experiments are briefly introduced.

    ↳ hep-exhep-phphysics.ins-det2 citations
20. 20*

    Electromagnetic probes of a pure-glue initial state in nucleus-nucleus collisions at energies available at the CERN Large Hadron Collider

    V. Vovchenko🇩🇪 · Iu. A. Karpenko🇺🇦 · M. I. Gorenstein🇺🇦 · L. M. Satarov🇩🇪 · I. N. Mishustin🇩🇪 · B. Kämpfer🇩🇪 · H. Stoecker🇩🇪

    Partonic matter produced in the early stage of ultrarelativistic nucleus-nucleus collisions is assumed to be composed mainly of gluons, and quarks and antiquarks are produced at later times. To study the implications of such a scenario, the dynamical evolution of a chemically nonequilibrated system is described by the ideal (2+1)-dimensional hydrodynamics with a time dependent (anti)quark fugacity. The equation of state interpolates linearly between the lattice data for the pure gluonic matter and the lattice data for the chemically equilibrated quark-gluon plasma. The spectra and elliptic flows of thermal dileptons and photons are calculated for central Pb+Pb collisions at the CERN Large Hadron Collider energy of $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV. We test the sensitivity of the results to the choice of equilibration times, including also the case where the complete chemical equilibrium of partons is reached already at the initial stage. It is shown that a suppression of quarks at early times leads to a significant reduction of the yield of the thermal dileptons, but only to a rather modest suppression of the $p_T$-distribution of direct photons. It is demonstrated that an enhancement of photon and dilepton elliptic flows might serve as a promising signature of the pure-glue initial state.

    ↳ nucl-thhep-phPRC(2016)·34 citations
21. 21*

    The SSM with Suppressed SUSY Charge

    John Dixon

    An earlier paper showed that it is possible to write down new SUSY Actions in which it is not possible to define a Supersymmetry Charge. SUSY is defined in these new Actions by the fact that they satisfy Master Equations. The new SUSY Actions are very easy to write down. One simply takes a Chiral SUSY Action, coupled to Gauge and other Chiral Multiplets, and even SuperGravity, if desired. Then one creates a new Action from this by exchanging all or part of the Scalar Field $S$ for a new Zinn Source $J$, and the corresponding part of the Zinn Source $\Gamma$ for a new Antighost Field $\eta$. Since the original Action satisfies a Master Equation, this exchange guarantees that the new Action will satisfy the new Master Equation. As was shown in the earlier paper, the new multiplets have fewer bosonic degrees of freedom than fermionic degrees of freedom. This is possible because they do not have a Supercharge. The resulting new SSM has no need for Squarks or Sleptons. It does not need spontaneous breaking of SUSY, so that the cosmological constant problem does not arise (at least at tree level). It mimics the usual non-supersymmetric Standard Model very well, and the absence of large flavour changing neutral currents is natural. There is no need for a hidden sector, or a messenger sector, or explicit `soft' breaking of SUSY. Spontaneous Gauge Symmetry Breaking implies the existence of two new very heavy Higgs Bosons with mass 13.4 TeV, slightly smaller than the energy of the LHC at 14 TeV. There is also a curious set of Gauginos and Higgsinos which have exactly the same masses as the Higgs and Gauge Bosons. These do not couple to the Quarks and Leptons, except through the Higgs and Gauge Bosons.

    ↳ hep-thhep-phPLB(2016)·4 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.