Mon·Aug 1, 2016Monday·August 1, 2016

1. 01*

   Critical number of fermions in three-dimensional QED

   V.P. Gusynin🇺🇦 · P.K. Pyatkovskiy🇨🇦

   Previous analytical studies of quantum electrodynamics in $2+1$ dimensions (QED3) have shown the existence of a critical number of fermions for onset of chiral symmetry breaking, the most known being the value $N_c\approx 3.28$ obtained by Nash to $1/N^2$ order in the $1/N$ expansion [16]. This analysis is reconsidered by solving the Dyson-Schwinger equations for the fermion propagator and the vertex to show that the more accurate gauge independent value is $N_c\approx 2.85$, and for $N<N_c$ the chiral symmetry is dynamically broken. An estimate for the value of chiral condensate $⟨\bar{\psi }\psi ⟩$ is given for $N=2$. Knowing precise $N_c$ would be important for comparison between continuum studies and lattice simulations of QED3.

   hep-phcond-mat.str-elhep-thPRD(2016)·57 citations
2. 02*

   Boosting to identify: pseudoscalar searches with di-leptonic tops

   Dorival Goncalves🇬🇧 · David Lopez-Val🇧🇪

   The quest for new heavy states is a critical component of the LHC physics program. In this letter, we study the search for pseudoscalar bosons produced in association with a $t\bar{t}$ pair. We consider the final state $t\bar{t}A\to t\bar{t}b\bar{b}$ with di-leptonic top pair signature, and reconstruct the boosted $A\to b\bar{b}$ candidate with jet substructure techniques, achieving a remarkable sensitivity over a broad range of pseudoscalar masses and Yukawa couplings. We apply this strategy to a Type-I Two-Higgs-Doublet Model, demonstrating its ability to probe a realistic, UV-complete extended Higgs sector. In particular, we find that the $13TeV$ LHC with $300f{b}^{-1}$ of data can constrain the region $\tan \beta >1.5$ at 95$\%$ CL for a light pseudoscalar with $m_A=50$ GeV. Moreover, the whole mass range $20GeV<m_A<210GeV$ can be ruled out for $\tan \beta \le 1$. Finally, we show that it is also possible to directly probe the CP-structure of the heavy scalar, and hence to distinguish a CP-odd (A) from a CP-even (H) 2HDM resonance.

   hep-phhep-exPRD(2016)·33 citations
3. 03*

   Unified Maximally Natural Supersymmetry

   Junwu Huang🇺🇸 · John March-Russell🇬🇧

   Maximally Natural Supersymmetry, an unusual weak-scale supersymmetric extension of the Standard Model based upon the inherently higher-dimensional mechanism of Scherk-Schwarz supersymmetry breaking (SSSB), possesses remarkably good fine tuning given present LHC limits. Here we construct a version with precision $SU(2{)}_{\mathrm{L}}\times U(1{)}_{\mathrm{Y}}$ unification: ${\sin }^2{\theta }_W(M_Z)\simeq 0.231$ is predicted to $\pm 2\%$ by unifying $SU(2{)}_{\mathrm{L}}\times U(1{)}_{\mathrm{Y}}$ into a 5D $SU(3{)}_{\mathrm{EW}}$ theory at a Kaluza-Klein scale of $1/R_5\sim 4.4\mathrm{TeV}$, where SSSB is simultaneously realised. Full unification with $SU(3{)}_{\mathrm{C}}$ is accommodated by extending the 5D theory to a $N=4$ supersymmetric $SU(6)$ gauge theory on a 6D rectangular orbifold at $1/R_6\sim 40\mathrm{TeV}$. TeV-scale states beyond the SM include exotic charged fermions implied by $SU(3{)}_{\mathrm{EW}}$ with masses lighter than $\sim 1.2\mathrm{TeV}$, and squarks in the mass range $1.4\mathrm{TeV}-2.3\mathrm{TeV}$, providing distinct signatures and discovery opportunities for LHC run II.

   hep-phhep-th3 citations
4. 04*

   Brief description of the flavor-changing neutral scalar interactions at two-loop level

   R. Gaitán🇲🇽 · J. A. Orduz-Ducuara🇲🇽

   In this letter we show a general description about flavor-changing neutral currents (FCNC) mediated by scalars. The analysis is extended at two-loop level for the Two-Higgs Doublet Model type-III because others models have strong constraints on its parameters, even at high orders of the perturbation. For this letter we focus on the standard model, calculating the amplitude for the $h\to \gamma \gamma$ process and discussing the results briefly.

   hep-phJ.Phys.Conf.Ser.(2016)·2 citations
5. 05*

   Search for a lighter Higgs in Two Higgs Doublet Models

   Giacomo Cacciapaglia🇫🇷 · Aldo Deandrea🇫🇷 · Suzanne Gascon🇫🇷 · Solene Le Corre🇫🇷 · Morgan Lethuillier🇫🇷 · Junquan Tao🇨🇳

   We consider present constraints on Two Higgs Doublet Models, both from the LHC at Run 1 and from other sources in order to explore the possibility of constraining a neutral scalar or pseudo-scalar particle lighter than the 125 GeV Higgs boson. Such a lighter particle is not yet completely excluded by present data. We show with a simplified analysis that some new constraints could be obtained at the LHC if such a search is performed by the experimental collaborations, which we therefore encourage to continue carrying out light diphoton resonance searches at $\sqrt{s}=$ 13 TeV in the context of Two Higgs Doublet Models.

   hep-phJHEP(2016)·48 citations
6. 06*

   One-Loop Corrections of Single Spin Asymmetries at Twist-3 in Drell-Yan Processes

   A.P. Chen🇨🇳 · J.P. Ma🇨🇳 · G.P. Zhang🇨🇳

   We study single spin asymmetries at one-loop accuracy in Drell-Yan processes in which one of the initial hadrons is transversely polarized. The spin-dependent part of differential cross-sections can be factorized with various hadronic matrix elements of twist-2 and twist-3 operators. These operators can be of even- and odd-chirality. In this work, the studied observables of asymmetries are differential cross-sections with different weights. These weights are selected so that the observables are spin-dependent and their virtual corrections are completely determined by quark form factor. In the calculations of one-loop corrections we meet collinear divergences in the contributions involving chirality-odd and chirality-even operators. We find that all of the divergences can be correctly subtracted. Therefore, our results give an explicit example of QCD factorization with twist-3 operators, especially, QCD factorization with chirality-odd twist-3 operators.

   hep-phPRD(2017)·14 citations
7. 07*

   Multiplicity distributions for $e^{+}{e}^{-}$ collisions using Weibull distribution

   Sadhana Dash🇮🇳 · Basanta. K. Nandi🇮🇳 · Priyanka Sett🇮🇳

   The two parameters Weibull function is used to describe the charged particle multiplicity distribution in $e^{+}{e}^{-}$ collisions at the highest available energy measured by TASSO and ALEPH experiments. The Weibull distribution has wide applications in naturally evolving processes based on fragmentation and sequential branching. The Weibull model describes the multiplicity distribution very well, as particle production processes involve QCD parton fragmentation. The effective energy model of particle production was verified using Weibull parameters and the same was used to predict the multiplicity distribution in $e^{+}{e}^{-}$ collisions at future collider energies.

   hep-phPRD(2016)·20 citations
8. 08*

   Renormalization group equation improved analysis of $B\to \pi$ form factors from Light-Cone Sum Rules

   Yue-Long Shen🇨🇳 · Yan-Bing Wei🇨🇳 · Cai-Dian Lü🇨🇳

   Within the framework of $B$-meson light-cone sum rules, we compute the one-loop level QCD corrections to $B\to \pi$ transition form factors at small $q^2$ region, in implement of a complete renormalization group equation evolution. To solve the renormalization group equations, we work at the "dual" space where the anomalous dimensions of the jet function and the light-cone distribution amplitudes are diagonal. With the complete renormalization group equation evolution, the form factors are almost independent of the factorization scale, which is shown numerically. We also extrapolate the results of the form factors to the whole $q^2$ region, and compare their behavior with other studies.

   hep-phPRD(2018)·22 citations
9. 09*

   Vacuum particle-antiparticle creation in strong fields as a field induced phase transition

   S. A. Smolyansky🇷🇺 · A. D. Panferov🇷🇺 · D. B. Blaschke🇷🇺 · L. Juchnowski🇵🇱 · B. Kaempfer🇩🇪 · A. Otto🇩🇪

   The features of vacuum particle creation in an external classical field are studied for simplest external field models in $3+1$ dimensional QED. The investigation is based on a kinetic equation that is a nonperturbative consequence of the fundamental equations of motion of QED. The observed features of the evolution of the system apply on the qualitative level also for systems of other nature and therefore are rather general. Examples from cosmology and condensed matter physics illustrate this statement. The common basis for the description of these systems are kinetic equations for vacuum particle creation belonging to the class of integro-differential equations of non-Markovian type with fastly oscillating kernel. This allows to characterize processes of this type as belonging to the class of field induced phase transitions.

   hep-phphysics.plasm-phRuss.Phys.J.(2017)·9 citations
10. 10*

    Massive photons from Super and Lorentz symmetry breaking

    Luca Bonetti🇫🇷 · Luís R. dos Santos Filho🇧🇷 · José A. Helayël-Neto🇧🇷 · Alessandro D.A.M. Spallicci🇫🇷

    In the context of Standard Model Extensions (SMEs), we analyse four general classes of Super Symmetry (SuSy) and Lorentz Symmetry (LoSy) breaking, leading to {observable} imprints at our energy scales. The photon dispersion relations show a non-Maxwellian behaviour for the CPT (Charge-Parity-Time reversal symmetry) odd and even sectors. The group velocities exhibit also a directional dependence with respect to the breaking background vector (odd CPT) or tensor (even CPT). In the former sector, the group velocity may decay following an inverse squared frequency behaviour. Thus, we extract a massive and gauge invariant Carroll-Field-Jackiw photon term in the Lagrangian and show that the mass is proportional to the breaking vector. The latter is estimated by ground measurements and leads to a photon mass upper limit of $10^{-19}$ eV or $2\times 10^{-55}$ kg and thereby to a potentially measurable delay at low radio frequencies.

    hep-phastro-ph.COgr-qcPLB(2017)·40 citations
11. 11*

    NNLO QCD corrections to Higgs boson production at large transverse momentum

    X. Chen🇨🇳 · J. Cruz-Martinez🇬🇧 · T. Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · M. Jaquier🇩🇪

    We derive the second-order QCD corrections to the production of a Higgs boson recoiling against a parton with finite transverse momentum, working in the effective field theory in which the top quark contributions are integrated out. To account for quark mass effects, we supplement the effective field theory result by the full quark mass dependence at leading order. Our calculation is fully differential in the final state kinematics and includes the decay of the Higgs boson to a photon pair. It allows one to make next-to-next-to- leading order (NNLO)-accurate theory predictions for Higgs-plus-jet final states and for the transverse momentum distribution of the Higgs boson, accounting for the experimental definition of the fiducial cross sections. The NNLO QCD corrections are found to be moderate and positive, they lead to a substantial reduction of the theory uncertainty on the predictions. We compare our results to 8 TeV LHC data from ATLAS and CMS. While the shape of the data is well-described for both experiments, we agree on the normalization only for CMS. By normalizing data and theory to the inclusive fiducial cross section for Higgs production, good agreement is found for both experiments, however at the expense of an increased theory uncertainty. We make predictions for Higgs production observables at the 13 TeV LHC, which are in good agreement with recent ATLAS data. At this energy, the leading order mass corrections to the effective field theory prediction become significant at large transverse momenta, and we discuss the resulting uncertainties on the predictions.

    hep-phhep-exJHEP(2016)·190 citations
12. 12*

    Gravitationally bound BCS state as dark matter

    Stephon Alexander🇺🇸 · Sam Cormack🇺🇸

    We explore the possibility that fermionic dark matter undergoes a BCS transition to form a superfluid. This requires an attractive interaction between fermions and we describe a possible source of this interaction induced by torsion. We describe the gravitating fermion system with the Bogoliubov-de Gennes formalism in the local density approximation. We solve the Poisson equation along with the equations for the density and gap energy of the fermions to find a self-gravitating, superfluid solution for dark matter halos. In order to produce halos the size of dwarf galaxies, we require a particle mass of $\sim 200\mathrm{eV}$. We find a maximum attractive coupling strength before the halo becomes unstable. If dark matter halos do have a superfluid component, this raises the possibility that they contain vortex lines.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2017)·33 citations
13. 13*

    New Limits on Thermally annihilating Dark Matter from Neutrino Telescopes

    José Lopes🇵🇹 · Ilídio Lopes🇵🇹

    We used a consistent and robust solar model to obtain upper limits placed by neutrino telescopes, such as Ice- Cube and Super-Kamiokande, on the Dark Matter-nucleon scattering cross-section, for a general model of Dark Matter with a velocity dependent (p-wave) thermally averaged cross-section. In this picture, the Boltzmann equation for the Dark Matter abundance is numerically solved satisfying the Dark Matter density measured from the Cosmic Microwave Background (CMB). We show that for lower cross-sections and higher masses, the Dark Matter annihilation rate drops sharply, resulting in upper bounds on the scattering cross-section one order of magnitude above those derived from a velocity independent (s-wave) annihilation cross-section. Our results show that upper limits on the scattering cross-section obtained from Dark Matter annihilating in the Sun are sensible to the uncertainty in current standard solar models, fluctuating a maximum of 20 % depending on the annihilation channel.

    ↳ astro-ph.COastro-ph.SRhep-phApJ(2016)·13 citations
14. 14*

    The $\{\beta \}$-expansion formalism in perturbative QCD and its extension

    A. L. Kataev🇷🇺 · S. V. Mikhailov🇷🇺

    We discuss the $\{\beta \}$-expansion for renormalization group invariant quantities tracing this expansion to the different contractions of the corresponding incomplete BPHZ $R$-operation. All of the coupling renormalizations, which follow from these contractions, should be taken into account for the $\{\beta \}$-expansion. We illustrate this feature considering the nonsinglet Adler function $D^{\text{NS}}$ in the third order of perturbation. We propose a generalization of the $\{\beta \}$-expansion for the renormalization group covariant quantities -- the $\{\beta ,\gamma \}$-expansion.

    ↳ hep-thhep-phJHEP(2016)·14 citations
15. 15*

    Dispersion by pulsars, magnetars, fast radio bursts and massive electromagnetism at very low radio frequencies

    Mark J. Bentum🇳🇱 · Luca Bonetti🇫🇷 · Alessandro D.A.M. Spallicci🇫🇷

    Our understanding of the universe relies mostly on electromagnetism. As photons are the messengers, fundamental physics is concerned in testing their properties. Photon mass upper limits have been earlier set through pulsar observations, but new investigations are offered by the excess of dispersion measure (DM) sometimes observed with pulsar and magnetar data at low frequencies, or with the fast radio bursts (FRBs), of yet unknown origin. Arguments for the excess of DM do not reach a consensus, but are not mutually exclusive. Thus, we remind that for massive electromagnetism, dispersion goes as the inverse of the frequency squared. Thereby, new avenues are offered also by the recently operating ground observatories in 10-80 MHz domain and by the proposed Orbiting Low Frequency Antennas for Radio astronomy (OLFAR). The latter acts as a large aperture dish by employing a swarm of nano-satellites observing the sky for the first time in the 0.1 - 15 MHz spectrum. The swarm must be deployed sufficiently away from the ionosphere to avoid distortions especially during the solar maxima, terrestrial interference and offer stable conditions for calibration during observations.

    ↳ astro-ph.IMastro-ph.HEgr-qchep-phAdv.Space Res.(2017)·31 citations
16. 16*

    Ferromagnetic detection of moduli dark matter

    A. Vinante🇮🇹

    We propose a scheme to detect light scalar moduli dark matter, based on measuring the change of magnetization induced in a macroscopic hard ferromagnet. Our method can probe moduli dark matter at the natural coupling to the electron mass over several orders of magnitude in the moduli mass. The most attracting feature of the proposed approach, compared to mechanical ones, is that it relies on a nonresonant detection, allowing to probe a much wider region of the parameter space. This is a crucial point, as long as the theory is not able to predict the moduli mass.

    ↳ physics.ins-dethep-exhep-ph0 citations
17. 17*

    Sneutrino Inflation with $\alpha$-attractors

    Renata Kallosh🇺🇸 · Andrei Linde🇺🇸 · Diederik Roest🇳🇱 · Timm Wrase🇦🇹

    Sneutrino inflation employs the fermionic partners of the inflaton and stabilizer field as right-handed neutrinos to realize the seesaw mechanism for light neutrino masses. We show that one can improve the latest version of this scenario and its consistency with the Planck data by embedding it in the theory of cosmological $\alpha$-attractors.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2016)·37 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.