Mon·May 1, 2017Monday·May 1, 2017

1. 01*

   A symmetry for ${ϵ}_K$

   Leandro Da Rold🇦🇷 · Iván A. Davidovich (Centro Atómico Bariloche, Instituto Balseiro and CONICET)🇦🇷

   We show a symmetry that, in the context of a composite Higgs with anarchic flavor, can suppress the dominant CP violating contributions to $K-\bar{K}$ mixing. Based on previous extensions of SU(3)${}_c$, we consider the case in which the composite sector has a global SU(6) symmetry, spontaneously broken to a subgroup containing SU(3)$\times$SU(3). We show that the interactions with the Standard Model can spontaneously break the remaining symmetry to the diagonal subgroup, identified with the group of color interactions, and naturally suppress ${ϵ}_K$. We consider this scenario in the context of the Minimal Composite Higgs Model based on SO(5)/SO(4) for the electroweak sector. By working in the framework of 2-site models, we compute the scalar potential, determine the conditions for a successful breaking of the symmetries and calculate the spectrum of lightest states. We find that ${ϵ}_K$ can be suppressed and the top mass reproduced for a large region of the parameter space where the symmetries are dynamically broken. Besides other new resonances, the model predicts the presence of a new singlet scalar state, generally lighter than the Higgs, that could have evaded detection at colliders.

   hep-phJHEP(2017)·4 citations
2. 02*

   Indirect Detection of Neutrino Portal Dark Matter

   Brian Batell🇺🇸 · Tao Han🇺🇸 · Barmak Shams Es Haghi🇺🇸

   We investigate the feasibility of the indirect detection of dark matter in a simple model using the neutrino portal. The model is very economical, with right-handed neutrinos generating neutrino masses through the Type-I seesaw mechanism and simultaneously mediating interactions with dark matter. Given the small neutrino Yukawa couplings expected in a Type-I seesaw, direct detection and accelerator probes of dark matter in this scenario are challenging. However, dark matter can efficiently annihilate to right-handed neutrinos, which then decay via active-sterile mixing through the weak interactions, leading to a variety of indirect astronomical signatures. We derive the existing constraints on this scenario from Planck cosmic microwave background measurements, Fermi dwarf spheroidal galaxies and Galactic Center gamma-rays observations, and Alpha Magnetic Spectrometer - 02 antiprotons observations, and also discuss the future prospects of Fermi and the Cherenkov Telescope Array. Thermal annihilation rates are already being probed for dark matter lighter than about 50 GeV, and this can be extended to dark matter masses of 100 GeV and beyond in the future. This scenario can also provide a dark matter interpretation of the Fermi Galactic Center gamma ray excess, and we confront this interpretation with other indirect constraints. Finally we discuss some of the exciting implications of extensions of the minimal model with large neutrino Yukawa couplings and Higgs portal couplings.

   hep-phastro-ph.HEPRD(2018)·89 citations
3. 03*

   The seesaw portal in testable models of neutrino masses

   A. Caputo🇪🇸 · P. Hernandez🇪🇸 · J. Lopez-Pavon🇨🇭 · J. Salvado🇪🇸

   A Standard Model extension with two Majorana neutrinos can explain the measured neutrino masses and mixings, and also account for the matter-antimatter asymmetry in a region of parameter space that could be testable in future experiments. The testability of the model relies to some extent on its minimality. In this paper we address the possibility that the model might be extended by extra generic new physics which we parametrize in terms of a low-energy effective theory. We consider the effects of the operators of the lowest dimensionality, $d=5$, and evaluate the upper bounds on the coefficients so that the predictions of the minimal model are robust. One of the operators gives a new production mechanism for the heavy neutrinos at LHC via higgs decays. The higgs can decay to a pair of such neutrinos that, being long-lived, leave a powerful signal of two displaced vertices. We estimate the LHC reach to this process.

   hep-phJHEP(2017)·111 citations
4. 04*

   Interpretation of $Y(4390)$ as an isoscalar partner of $Z(4430)$ from $D^{\ast }(2010){\bar{D}}_1(2420)$ interaction

   Jun He🇨🇳 · Dian-Yong Chen🇨🇳

   Invoked by the recent observation of $Y(4390)$ at BESIII, which is about 40 MeV below the $D^{\ast }(2010){\bar{D}}_1(2420)$ threshold, we investigate possible bound and resonance states from the $D^{\ast }(2010){\bar{D}}_1(2420)$ interaction with the one-boson-exchange model in a quasipotential Bethe-Salpeter equation approach. A bound state with quantum number $0^{-}(1^{--})$ is produced at 4384 MeV from the $D^{(}2010){\bar{D}}_1(2420)$ interaction, which can be related to experimentally observed $Y(4390)$. Another state with quantum number $1^{+}(1^{+})$ is also produced at $4461+i39$ MeV from this interaction. Different from the $0^{-}(1^{--})$ state, the $1^{+}(1^{+})$ state is a resonance state above the $D^{\ast }(2010){\bar{D}}_1(2420)$ threshold. This resonance state can be related to the first observed charged charmonium-like state $Z(4430)$, which has a mass about 4475 MeV measured above the threshold as observed at Belle and LHCb. Our result suggests that $Y(4390)$ is an isoscalar partner of the $Z(4430)$ as a hadronic-molecular state from the $D^{\ast }(2010){\bar{D}}_1(2420)$ interaction.

   hep-phhep-exhep-latnucl-thEPJC(2017)·19 citations
5. 05*

   Production and absorption of exotic bottomonium-like states in high energy heavy ion collisions

   L. M. Abreu🇧🇷 · K. P. Khemchandani🇧🇷 · A. Martínez Torres🇧🇷 · F. S. Navarra🇧🇷 · M. Nielsen🇧🇷 · A. L. Vasconcellos🇧🇷

   We investigate the production and absorption of $Z_b(10610)$ and $Z_b^{\prime }(10650)$ states in a hadronic medium, via the processes ${\bar{B}}^{(\ast )}{B}^{(\ast )}\to \pi Z_b^{(\prime )}$ and the corresponding inverses reactions. We use effective field Lagrangians based on an $SU(4)$-extension of the hidden gauge formalism to account for the couplings between light and heavy mesons, and a phenomenological Lagrangian involving the $B^{\ast }{B}^{(\ast )}{Z}_b^{(\prime )}$ vertices. The absorption cross sections are found to be much larger than the production ones.

   hep-phnucl-thPRD(2017)·11 citations
6. 06*

   Special Grand Unification

   Naoki Yamatsu🇯🇵

   We discuss new-type grand unified theories based on grand unified groups broken to their special subgroups as well as their regular subgroups. In the framework, when we construct four-dimensional (4D) chiral gauge theories, i.e., the Standard Model (SM), 4D gauge anomaly cancellation restricts the minimal number of generations of the 4D SM Weyl fermions. We show that in a six-dimensional (6D) $SU(16)$ gauge theory on $M^4\times T^2/{\mathbb{Z}}_2$ one generation of the SM fermions can be embedded into a 6D bulk Weyl fermion. For the model including three chiral generations of the SM fermions, the 6D and 4D gauge anomalies on the bulk and fixed points are canceled out without exotic 4D chiral fermions.

   hep-phhep-thPTEP(2017)·19 citations
7. 07*

   Exact treatment of dispersion relations in pp and pp̄ elastic scattering

   E. Ferreira🇧🇷 · A. K. Kohara🇧🇷 · J. Sesma🇪🇸

   Based on a study of the properties of the Lerch's transcendent, exact closed forms of dispersion relations for amplitudes and for derivatives of amplitudes in pp and pp̄ scattering are introduced. Exact and complete expressions are written for the real parts and for their derivatives at $t=0$ based on given inputs for the energy dependence of the total cross sections and of the slopes of the imaginary parts. The results are prepared for application in the analysis of forward scattering data of the pp and pp̄ systems at all energies, where exact and precise representations can be written.

   hep-phmath-phmath.MPPRC(2018)·8 citations
8. 08*

   Corrections to (pseudo)scalars decay into a fermion pair from gravitational torsion

   Felipe Rojas Abatte🇨🇱 · Jilberto Zamora-Saa🇷🇺 · Oscar Castillo-Felisola🇨🇱 · Bastian Diaz🇨🇱 · Alfonso R. Zerwekh🇨🇱

   We study the contribution of the torsion-descendent four-fermion contact interaction to the decay width of a neutral (pseudo)scalar field into a fermion pair. This new interaction comes from the existence of gravitational torsion in models with extra dimensions. Additionally, we exemplify the formalism with two examples: first, the variation of the considered branching ratio of the Higgs in the context of the standard model, and second the proper variations of the scalar and pseudo scalar fields of the type II-1 two Higgs doublets model.

   hep-phActa Phys.Polon.B(2018)·2 citations
9. 09*

   Transverse parton momenta in single inclusive hadron production in $e^{+}{e}^{-}$ annihilation processes

   M. Boglione🇮🇹 · J.O. Gonzalez-Hernandez🇮🇹 · R. Taghavi🇮🇷

   We study the transverse momentum distributions of single inclusive hadron production in $e^{+}{e}^{-}$ annihilation processes. Although the only available experimental data are scarce and quite old, we find that the fundamental features of transverse momentum dependent (TMD) evolution, historically addressed in Drell-Yan processes and, more recently, in Semi-inclusive deep inelastic scattering processes, are visible in $e^{+}{e}^{-}$ annihilations as well. Interesting effects related to its non-perturbative regime can be observed. We test two different parameterizations for the $p_{\perp }$ dependence of the cross section: the usual Gaussian distribution and a power-law model. We find the latter to be more appropriate in describing this particular set of experimental data, over a relatively large range of $p_{\perp }$ values. We use this model to map some of the features of the data within the framework of TMD evolution, and discuss the caveats of this and other possible interpretations, related to the one-dimensional nature of the available experimental data.

   hep-phPLB(2017)·31 citations
10. 10*

    Simulations of Cold Electroweak Baryogenesis: Hypercharge U(1) and the creation of helical magnetic fields

    Zong-Gang Mou🇳🇴 · Paul M. Saffin🇬🇧 · Anders Tranberg🇳🇴

    We perform numerical simulations of Cold Electroweak Baryogenesis, including for the first time in the Bosonic sector the full electroweak gauge group SU(2)$\times$U(1) and CP-violation. We find that the maximum generated baryon asymmetry is reduced by a factor of three relative to the SU(2)-only model, but that the quench time dependence is very similar. In addition, we compute the magnitude of the helical magnetic fields, and find that it is proportional to the strength of CP-violation and dependent on quench time, but is not proportional to the magnitude of the baryon asymmetry as proposed in the literature. Astrophysical signatures of primordial magnetic helicity can therefore not in general be used as evidence that electroweak baryogenesis has taken place.

    hep-phhep-lathep-thJHEP(2017)·13 citations
11. 11*

    Feynman integrals and iterated integrals of modular forms

    Luise Adams🇩🇪 · Stefan Weinzierl🇩🇪

    In this paper we show that certain Feynman integrals can be expressed as linear combinations of iterated integrals of modular forms to all orders in the dimensional regularisation parameter $\epsilon$ . We discuss explicitly the equal mass sunrise integral and the kite integral. For both cases we give the alphabet of letters occurring in the iterated integrals. For the sunrise integral we present a compact formula, expressing this integral to all orders in $\epsilon$ as iterated integrals of modular forms.

    hep-phhep-thmath-phmath.MPCommun.Num.Theor.Phys.(2018)·170 citations
12. 12*

    Status and challenges of neutrino cross sections

    Marco Martini🇫🇷

    Neutrino oscillations physics entered in the precision era. In this context accelerator-based neutrino experiments need a reduction of systematic errors to the level of a few percent. Today one of the most important sources of systematic errors are the neutrino-nucleus cross sections. The status of our knowledge of these cross sections in the different open channels in the few-GeV region, i.e. the quasielastic, the pion production and the multinucleon emission, is reviewed. Special emphasis is devoted to the multinucleon emission channel, which attracted a lot of attention in the last few years. It is crucial to properly reconstruct the neutrino energy which enters the expression of the oscillation probability. This channel was not included in the generators used for the analyses of the neutrino cross sections and oscillations experiments.

    hep-phhep-exnucl-th0 citations
13. 13*

    Is electroweak baryogenesis dead?

    James M. Cline🇨🇦

    Electroweak baryogenesis is severely challenged in its traditional settings: the Minimal Supersymmetric Standard Model, and in more general two Higgs doublet models. Fine tuning of parameters is required, or large couplings leading to a Landau pole at scales just above the new physics introduced. The situation is somewhat better in models with a singlet scalar coupling to the Higgs so as to give a strongly first order phase transition due to a tree-level barrier, but even in this case no UV complete models had been demonstrated to give successful baryogenesis. Here we point out some directions that overcome this limitation, by introducing a new source of CP violation in the couplings of the singlet field. A model of electroweak baryogenesis requiring no fine tuning and consistent to scales far above 1 TeV is demonstrated, in which dark matter plays the leading role in creating a CP asymmetry that is the source of the baryon asymmetry.

    hep-phPhil.Trans.Roy.Soc.Lond.A(2018)·53 citations
14. 14*

    Pulse shape optimization for electron-positron production in rotating fields

    François Fillion-Gourdeau🇨🇦 · Florian Hebenstreit🇨🇭 · Denis Gagnon🇨🇦 · Steve MacLean🇨🇦

    We optimize the pulse shape and polarization of time-dependent electric fields to maximize the production of electron-positron pairs via strong field quantum electrodynamics processes. The pulse is parametrized in Fourier space by a B-spline polynomial basis, which results in a relatively low-dimensional parameter space while still allowing for a large number of electric field modes. The optimization is performed by using a parallel implementation of the differential evolution, one of the most efficient metaheuristic algorithms. The computational performance of the numerical method and the results on pair production are compared with a local multistart optimization algorithm. These techniques allow us to determine the pulse shape and field polarization that maximize the number of produced pairs in computationally accessible regimes.

    hep-phquant-phPRD(2017)·25 citations
15. 15*

    Moriond QCD 2017: theoretical summary

    Oleg Lebedev🇫🇮

    I summarize the highlights of the theory talks at the 52nd Rencontres de Moriond: QCD and high energy interactions.

    hep-ph0 citations
16. 16*

    High-$p_T$ dilepton tails and flavour physics

    Admir Greljo🇨🇭 · David Marzocca🇨🇭

    We investigate the impact of flavour-conserving, non-universal quark-lepton contact interactions on the dilepton invariant mass distribution in $pp\to {\ell }^{+}{\ell }^{-}$ processes at the LHC. After recasting the recent ATLAS search performed at 13 TeV with 36.1 fb${}^{-1}$ of data, we derive the best up-to-date limits on the full set of 36 relevant four-fermion operators, as well as estimate the sensitivity achievable at the HL-LHC. We discuss how these high-$p_T$ measurements can provide complementary information to the low-$p_T$ rare meson decays. In particular, we find that the recent hints on lepton flavour universality violation in $b\to s{\mu }^{+}{\mu }^{-}$ transitions are already in mild tension with the dimuon spectrum at high-$p_T$ if the flavour structure follows minimal flavour violation. Even if the mass scale of New Physics is well beyond the kinematical reach for on-shell production, the signal in the high-$p_T$ dilepton tail might still be observed, a fact that has been often overlooked in the present literature. In scenarios where new physics couples predominantly to third generation quarks, instead, the HL-LHC phase is necessary in order to provide valuable information.

    hep-phhep-exEPJC(2017)·265 citations
17. 17*

    Fisher matrix forecasts for astrophysical tests of the stability of the fine-structure constant

    C. S. Alves🇵🇹 · T. A. Silva🇵🇹 · C. J. A. P. Martins🇵🇹 · A. C. O. Leite🇵🇹

    We use Fisher Matrix analysis techniques to forecast the cosmological impact of astrophysical tests of the stability of the fine-structure constant to be carried out by the forthcoming ESPRESSO spectrograph at the VLT (due for commissioning in late 2017), as well by the planned high-resolution spectrograph (currently in Phase A) for the European Extremely Large Telescope. Assuming a fiducial model without $\alpha$ variations, we show that ESPRESSO can improve current bounds on the Eötvös parameter---which quantifies Weak Equivalence Principle violations---by up to two orders of magnitude, leading to stronger bounds than those expected from the ongoing tests with the MICROSCOPE satellite, while constraints from the E-ELT should be competitive with those of the proposed STEP satellite. Should an $\alpha$ variation be detected, these measurements will further constrain cosmological parameters, being particularly sensitive to the dynamics of dark energy.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2017)·6 citations
18. 18*

    Bounds on the Polymer Scale from Gamma Ray Bursts

    Yuri Bonder🇲🇽 · Angel Garcia-Chung🇲🇽 · Saeed Rastgoo🇲🇽

    The polymer representations, which are partially motivated by loop quantum gravity, have been suggested as alternative schemes to quantize the matter fields. Here we apply a version of the polymer representations to the free electromagnetic field, in a reduced phase space setting, and derive the corresponding effective (i.e., semiclassical) Hamiltonian. We study the propagation of an electromagnetic pulse and we confront our theoretical results with gamma ray burst observations. This comparison reveals that the dimensionless polymer scale must be smaller than $4\times 10^{-35}$, casting doubts on the possibility that the matter fields are quantized with the polymer representation we employed.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2017)·9 citations
19. 19*

    Large gauge transformation and little group for soft photons

    Yuta Hamada🇯🇵 · Min-Seok Seo🇰🇷 · Gary Shiu🇺🇸

    Recently, large gauge transformation (LGT), the residual gauge symmetry after gauge fixing that survives at null infinity, has drawn much attention concerning soft theorems and the memory effect. We point out that LGT charges in quantum electrodynamics are in fact one of non-compact generators of the two dimensional Euclidean group. Moreover, by comparing two equivalent descriptions of gauge transformation, we suggest that LGT is simply another way of describing the gauged little group for massless soft photons.

    ↳ hep-thhep-phPRD(2017)·15 citations
20. 20*

    Sterile Neutrinos: Reactor Experiments

    Christian Buck🇩🇪

    Nuclear reactors are strong, pure and well localized sources of electron antineutrinos with energies in the few MeV range. Therefore they provide a suitable environment to study neutrino properties, in particular neutrino oscillation parameters. Recent predictions of the expected antineutrino flux at nuclear reactors are about 6% higher than the average rate measured in different experiments. This discrepancy, known as the reactor antineutrino anomaly, is significant at the 2.5{\sigma} level. Several new experiments are searching for the origin of this observed neutrino deficit. One hypothesis to be tested is an oscillation to another neutrino state. In a three flavor model reactor neutrinos do not oscillate at baselines below 100 m. Hence, if such an oscillation is observed, it would imply the existence of at least one light sterile neutrino state not participating in weak interactions. Such a discovery would open the gate for new physics beyond the Standard Model.

    ↳ hep-exhep-phphysics.ins-det0 citations
21. 21*

    Two bosons in a narrowly resonant trap

    Bingwei Long🇨🇳 · Jianfeng Wang🇨🇳 · Songlin Lyu🇨🇳

    It is rare for an $S$-wave resonance to remain narrow while approaching threshold as a result of the interaction parameters being fine tuned. Such an interaction is, however, realized by pion-charmed baryon system $\pi {\Sigma }_c$, which has a narrow resonance ${\Lambda }_c^{+}(2595)$ located a few MeVs above its threshold. We study the consequence of narrowly resonant inter-species interaction in a three-body system composed of two identical light bosons and an extremely heavy particle. We concern ourselves in the present paper with resonances of the three-body system, as opposed to bound states. The focus is on the technical aspects of constructing the integral equation for three-body amplitudes and of analytically continuing the integral equation to locate the "trimer" resonance pole in the unphysical sheet of the center-of-mass energy plane.

    ↳ nucl-thcond-mat.quant-gashep-ph3 citations
22. 22*

    Elastic and inelastic pion-nucleon scattering to fourth order in chiral perturbation theory

    D. Siemens🇩🇪 · V. Bernard🇫🇷 · E. Epelbaum🇩🇪 · A. M. Gasparyan🇩🇪 · H. Krebs🇩🇪 · Ulf-G. Meißner🇩🇪

    We extend our previous study of elastic pion-nucleon scattering in the framework of chiral perturbation theory by performing a combined analysis of the reactions $\pi N\to \pi N$ and $\pi N\to \pi \pi N$. The calculation is carried out to fourth order in the chiral expansion using the heavy baryon approach and the covariant formulation supplemented with a modified version of the extended on-mass-shell renormalization scheme. We demonstrate that a combined fit to experimental data in both channels leads to a reduced amount of correlations between the low-energy constants. A satisfactory description of the experimental data in both channels is obtained, which is further improved upon including tree-level contributions of the $\Delta$(1232) resonance. We also explore a possibility of using the empirical information about $\pi N$ subthreshold parameters obtained recently by means of the Roy-Steiner equations to stabilize the fits.

    ↳ nucl-thhep-phPRC(2017)·35 citations
23. 23*

    From deep inelastic scattering to heavy-flavor semi-leptonic decays: Total rates into multi-hadron final states from lattice QCD

    Maxwell T. Hansen🇩🇪 · Harvey B. Meyer🇩🇪 · Daniel Robaina🇩🇪

    We present a new technique for extracting decay and transition rates into final states with any number of hadrons. The approach is only sensitive to total rates, in which all out-states with a given set of QCD quantum numbers are included. For processes involving photons or leptons, differential rates with respect to the non-hadronic kinematics may also be extracted. Our method involves constructing a finite-volume Euclidean four-point function, whose corresponding spectral function measures the decay and transition rates in the infinite-volume limit. This requires solving the inverse problem of extracting the spectral function from the correlator and also necessitates a smoothing procedure so that a well-defined infinite-volume limit exists. Both of these steps are accomplished by the Backus-Gilbert method and, as we show with a numerical example, reasonable precision can be expected in cases with multiple open decay channels. Potential applications include nucleon structure functions and the onset of the deep inelastic scattering regime, as well as semi-leptonic $D$ and $B$ decay rates.

    ↳ hep-lathep-phPRD(2017)·158 citations
24. 24*

    Relativistic fluid dynamics with spin

    Wojciech Florkowski🇵🇱 · Bengt Friman🇩🇪 · Amaresh Jaiswal🇮🇳 · Enrico Speranza🇩🇪

    Using the conservation laws for charge, energy, momentum, and angular momentum, we derive hydrodynamic equations for the charge density, local temperature, and fluid velocity, as well as for the spin tensor, starting from local equilibrium distribution functions for particles and antiparticles with spin 1/2. The resulting set of differential equations extend the standard picture of perfect-fluid hydrodynamics with a conserved entropy current in a minimal way. This framework can be used in space-time analyzes of the evolution of spin and polarization in various physical systems including high-energy nuclear collisions. We demonstrate that a stationary vortex, which exhibits vorticity-spin alignment, corresponds to a special solution of the spin-hydrodynamical equations.

    ↳ nucl-thhep-phnucl-exPRC(2018)·327 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.