Fri·Mar 3, 2017Friday·March 3, 2017

1. 01*

   Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

   Iason Baldes🇩🇪 · Kalliopi Petraki🇫🇷

   Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

   hep-phJCAP(2017)·107 citations
2. 02*

   A Two Loop Radiative Neutrino Model

   Seungwon Baek🇰🇷 · Hiroshi Okada🇹🇼 · Yuta Orikasa🇨🇿

   We explore the possibility to explain a bosonic dark matter candidate with a gauge singlet inside the loop to generate the neutrino mass matrix at two-loop level. The mass matrix is suppressed by a small mixing that comes from the bound on {direct detection experiments of the dark matter, and equivalent of the three-loop neutrino model due to the small mixing between neutral inert bosons. Here, our setup is} the Zee-Babu type scenario with $Z_3$ discrete symmetry, in which we consider the neutrino oscillation data, lepton flavor violations, muon $g-2$, $\mu -e$ conversion rate, lepton flavor-changing and conserving $Z$ boson decay and bosonic dark matter candidate.

   hep-phNPB(2019)·19 citations
3. 03*

   Effects of coupled channels on $c\bar{b}$ mass and decays in NRQM with OGEP

   Manjunath Bhat🇮🇳 · Antony Prakash Monteiro🇮🇳 · K. B. Vijaya Kumar🇮🇳

   The complete spectrum of $c\bar{b}$ states is obtained in a phenomenological non relativistic quark model(NRQM), which consists of a confinement potential and one gluon exchange potential (OGEP) as effective quark - antiquark potential with coupled channel effects. We make predictions for the radiative decay (E1 and M1) widths and weak decay widths of $c\bar{b}$ states in the framework of NRQM formalism.

   hep-phIJMPE(2017)·4 citations
4. 04*

   Structures of Neutrino Mass Spectrum and Lepton Mixing: Results of Violated Mirror Symmetry

   Igor T. Dyatlov🇷🇺

   The specific violated mirror symmetry model is capable of generating the observed lepton weak mixing matrix with a structure similar to the observed one that almost lacks any visible regularities (the "flavor riddle"). The peculiarities of the Standard Model (SM): quark and lepton mass hierarchy and the neutrino spectrum different from this hierarchy appear to be necessary conditions for reproduction of such a structure. The inverse order of the neutrino spectrum and a small value of the mass $m_3$ are here two other necessary conditions. The smallness of the angle ${\Theta }_{1,3}$ is determined then just by small mass ratios in the hierarchical lepton spectrum. The explanation is proposed for differences between the neutrino spectrum and other fermion spectra of SM. The inverse order of the neutrino spectrum and the observed ${\Theta }_{1,3}$ angle permit evaluation of the absolute values of neutrino masses: $m_1\sim m_2\sim 0.05$eV, $m_3\le 0.01$eV.

   hep-phPhys.Atom.Nucl.(2017)·4 citations
5. 05*

   String dynamics and metastability of fully-heavy tetraquarks

   Jean-Marc Richard (Lyon)🇫🇷 · Alfredo Valcarce (Salamanca)🇪🇸 · Javier Vijande (Valencia)🇪🇸

   Multiquark states have been advocated to explain recent experimental data in the heavy-light sector, and there are already speculations about multiquarks containing only heavy quarks and antiquarks. With a rigorous treatment of the four-body problem in current quark models, full-charm $(cc\bar{c}\bar{c})$ and full-beauty $(bb\bar{b}\bar{b})$ tetraquarks are found to be unbound. Thus their stability should rely on more subtle effects that are not included in the simple picture of constituent quarks. The case of $(bc\bar{b}\bar{c})$ might be more favorable if the naive color-additive model of confinement is replaced by a string-inspired interaction.

   hep-phhep-exnucl-thPRD(2017)·117 citations
6. 06*

   Naturalness in testable type II seesaw scenarios

   P. S. Bhupal Dev🇺🇸 · Clara Miralles Vila🇩🇪 · Werner Rodejohann🇩🇪

   New physics coupling to the Higgs sector of the Standard Model can lead to dangerously large corrections to the Higgs mass. We investigate this problem in the type II seesaw model for neutrino mass, where a weak scalar triplet is introduced. The interplay of direct and indirect constraints on the type II seesaw model with its contribution to the Higgs mass is analyzed. The focus lies on testable triplet masses and (sub) eV-scale triplet vacuum expectation values. We identify scenarios that are testable in collider and/or lepton flavor violation experiments, while satisfying the Higgs naturalness criterion.

   hep-phhep-exNPB(2017)·54 citations
7. 07*

   Pseudo-Goldstone excitations in chiral Yukawa-theories with quadratic explicit symmetry breaking

   A. Jakovác🇭🇺 · I. Kaposvári🇭🇺 · A. Patkós🇭🇺

   The symmetry breakdown pattern is studied in models containing one fermion flavor multiplet and a multicomponent scalar field, supplemented with a chiral Yukawa-interaction, and in presence of an explicit symmetry breaking source quadratic in the scalar field. In a detailed investigation of the model with $U_L(1)\times U_R(1)$ chiral symmetry it is shown that by diminishing the strength of quadratic explicit symmetry breaking one can still keep stable the mass ratio of the fermionic and the pseudo-Goldstone excitation. At the same time the mass ratio of the two bosonic excitations appears to approach a limiting value depending only on the infrared value of the first ratio, but not on the microscopic (ultraviolet) coupling values. The observations receive a general interpretation by the existence of an ultraviolet fixed point located in the symmetric phase. Understanding the general conditions for its existence allows the construction of a similar theory with $U_L(2)\times U_R(2)$ chiral symmetry. All results of the present investigation were obtained with nonperturbative functional renormalisation group technique making use of the first two approximations to the gradient expansion of the effective action.

   hep-phhep-thPRD(2017)·2 citations
8. 08*

   Towards understanding thermal history of the Universe through direct and indirect detection of dark matter

   Leszek Roszkowski🇵🇱 · Sebastian Trojanowski🇺🇸 · Krzysztof Turzynski🇵🇱

   We examine the question to what extent prospective detection of dark matter by direct and indirect- detection experiments could shed light on what fraction of dark matter was generated thermally via the freeze-out process in the early Universe. By simulating putative signals that could be seen in the near future and using them to reconstruct WIMP dark matter properties, we show that, in a model- independent approach this could only be achieved in a thin sliver of the parameter space. However, with additional theoretical input the hypothesis about the thermal freeze-out as the dominant mechanism for generating dark matter can potentially be verified. We illustrate this with two examples: an effective field theory of dark matter with a vector messenger and a higgsino or wino dark matter within the MSSM.

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

   Updated Global 3+1 Analysis of Short-BaseLine Neutrino Oscillations

   S. Gariazzo🇪🇸 · C. Giunti🇮🇹 · M. Laveder🇮🇹 · Y.F. Li🇨🇳

   We present the results of an updated fit of short-baseline neutrino oscillation data in the framework of 3+1 active-sterile neutrino mixing. We first consider ${\nu }_e$ and ${\bar{\nu }}_e$ disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor ${\bar{\nu }}_e$ spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of $|U_{e4}{|}^2$. The beta-decay constraints allow us to limit the oscillation length between about 2 cm and 7 m at $3\sigma$ for neutrinos with an energy of 1 MeV. We then consider the global fit of the data in the light of the LSND anomaly, taking into account the constraints from ${\nu }_e$ and ${\nu }_{\mu }$ disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on $|U_{e4}{|}^2$ and the MINOS and IceCube constraints on $|U_{\mu 4}{|}^2$ lead to an unacceptable appearance-disappearance tension which becomes tolerable only in a pragmatic fit which neglects the MiniBooNE low-energy anomaly. The minimization of the global ${\chi }^2$ in the space of the four mixing parameters $\Delta m_{41}^2$, $|U_{e4}{|}^2$, $|U_{\mu 4}{|}^2$, and $|U_{\tau 4}{|}^2$ leads to three allowed regions with narrow $\Delta m_{41}^2$ widths at $\Delta m_{41}^2\approx 1.7$ (best-fit), 1.3 (at $2\sigma$), 2.4 (at $3\sigma$) eV${}^2$. The restrictions of the allowed regions of the mixing parameters with respect to our previous global fits are mainly due to the NEOS constraints. We present a comparison of the allowed regions of the mixing parameters with the sensitivities of ongoing experiments, which show that it is likely that these experiments will determine in a definitive way if the reactor, Gallium and LSND anomalies are due to active-sterile neutrino oscillations or not.

   hep-phhep-exJHEP(2017)·306 citations
10. 10*

    Optimal renormalization and the extraction of strange quark mass from semi-leptonic $\tau$-decay

    B. Ananthanarayan🇮🇳 · Diganta Das🇮🇳

    We employ optimal renormalization group analysis to semi-leptonic $\tau$-decay polarization functions and extract the strange quark mass from their moments measured by the ALEPH and OPAL collaborations. The optimal renormalization group makes use of the renormalization group equation of a given perturbation series which then leads to closed form sum of all the renormalization group-accessible logarithms which have reduced scale dependence. Using the latest theoretical inputs we find $m_s(2\mathrm{GeV})=106.70\pm 9.36\mathrm{MeV}$ and $m_s(2\mathrm{GeV})=74.47\pm 7.77\mathrm{MeV}$ for ALEPH and OPAL data respectively.

    hep-phSpringer Proc.Phys.(2018)·0 citations
11. 11*

    Lepton flavor violating Higgs boson decays in seesaw models: new discussions

    N.H. Thao🇻🇳 · L.T. Hue🇻🇳 · H.T. Hung🇻🇳 · N.T. Xuan🇻🇳

    The lepton flavor violating decay of the Standard Model-like Higgs boson (LFVHD), h->\mu\tau, is discussed in seesaw models at the one-loop level. Based on particular analytic expressions of Passarino-Veltman functions, the two unitary and 't Hooft Feynman gauges are used to compute the branching ratio of LFVHD and compare with results reported recently. In the minimal seesaw (MSS) model, the branching ratio was investigated in the whole valid range 10^{-9}-10^{15} GeV of new neutrino mass scale m_{n_6}. Using the Casas-Ibarra parameterization, this branching ratio enhances with large and increasing m_{n_6}. But the maximal value can reach only order of 10^{-11}. Interesting relations of LFVHD predicted by the MSS and inverse seesaw (ISS) model are discussed. The ratio between two LFVHD branching ratios predicted by the ISS and MSS is simply m^2_{n_6}\mu^{-2}_X, where \mu_X is the small neutrino mass scale in the ISS. The consistence between different calculations is shown precisely from analytical approach.

    hep-phNPB(2017)·31 citations
12. 12*

    New Constraints and Prospects for sub-GeV Dark Matter Scattering off Electrons in Xenon

    Rouven Essig🇺🇸 · Tomer Volansky🇮🇱 · Tien-Tien Yu🇨🇭

    We study in detail sub-GeV dark matter scattering off electrons in xenon, including the expected electron recoil spectra and annual modulation spectra. We derive improved constraints using low-energy XENON10 and XENON100 ionization-only data. For XENON10, in addition to including electron-recoil data corresponding to about $1-3$ electrons, we include for the first time events with $\gtrsim 4$ electrons. Assuming the scattering is momentum independent, this strengthens a previous cross-section bound by almost an order of magnitude for dark matter masses above 50 MeV. The available XENON100 data corresponds to events with $\gtrsim 4$ electrons, and leads to a constraint that is comparable to the XENON10 bound above 50 MeV. We demonstrate that a search for an annual modulation signal in upcoming xenon experiments (XENON1T, XENONnT, LZ) could substantially improve the above bounds even in the presence of large backgrounds. We also emphasize that in simple benchmark models of sub-GeV dark matter, the dark matter-electron scattering rate can be as high as one event every ten (two) seconds in the XENON1T (XENONnT or LZ) experiments, without being in conflict with any other known experimental bounds. While there are several sources of backgrounds that can produce single- or few-electron events, a large event rate can be consistent with a dark matter signal and should not be simply written off as purely a detector curiosity. This fact motivates a detailed analysis of the ionization-only ("S2-only") data, taking into account the expected annual modulation spectrum of the signal rate, as well as the DM-induced electron-recoil spectra, which are another powerful discriminant between signal and background.

    hep-phastro-ph.COPRD(2017)·474 citations
13. 13*

    Constraining Quirky Tracks with Conventional Searches

    Marco Farina🇺🇸 · Matthew Low🇺🇸

    Quirks are particles that are both charged under the standard model and under a new confining group. The quirk setup assumes there are no light flavors of the new confining group so that while the theory is in a confining phase, the distance between quirk-antiquirk pairs can be macroscopic. In this work, we reinterpret existing collider limits, those from monojet and heavy stable charged particle searches, as limits on quirks. Additionally, we propose a new search in the magnetic-field-less CMS data for quirks and estimate the sensitivity. We focus on the region where the confinement scale is roughly between 1 eV and 100 eV and find mass constraints in the TeV-range, depending on the quirk's quantum numbers.

    hep-phhep-exPRL(2017)·27 citations
14. 14*

    Fractal based observables to probe jet substructure of quarks and gluons

    Joe Davighi🇬🇧 · Philip Harris🇨🇭

    New jet observables are defined which characterize both fractal and scale-dependent contributions to the distribution of hadrons in a jet. These infrared safe observables, named Extended Fractal Observables (EFOs), have been applied to quark-gluon discrimination to demonstrate their potential utility. The EFOs are found to be individually discriminating and only weakly correlated to variables used in existing discriminators. Consequently, their inclusion improves discriminator performance, as here demonstrated with particle level simulation from the parton shower.

    hep-phhep-exEPJC(2018)·28 citations
15. 15*

    Theta, Time Reversal, and Temperature

    Davide Gaiotto🇨🇦 · Anton Kapustin🇺🇸 · Zohar Komargodski🇮🇱 · Nathan Seiberg🇺🇸

    $SU(N)$ gauge theory is time reversal invariant at $\theta =0$ and $\theta =\pi$. We show that at $\theta =\pi$ there is a discrete 't Hooft anomaly involving time reversal and the center symmetry. This anomaly leads to constraints on the vacua of the theory. It follows that at $\theta =\pi$ the vacuum cannot be a trivial non-degenerate gapped state. (By contrast, the vacuum at $\theta =0$ is gapped, non-degenerate, and trivial.) Due to the anomaly, the theory admits nontrivial domain walls supporting lower-dimensional theories. Depending on the nature of the vacuum at $\theta =\pi$, several phase diagrams are possible. Assuming area law for space-like loops, one arrives at an inequality involving the temperatures at which CP and the center symmetry are restored. We also analyze alternative scenarios for $SU(2)$ gauge theory. The underlying symmetry at $\theta =\pi$ is the dihedral group of 8 elements. If deconfined loops are allowed, one can have two $O(2)$-symmetric fixed points. It may also be that the four-dimensional theory around $\theta =\pi$ is gapless, e.g. a Coulomb phase could match the underlying anomalies.

    ↳ hep-thhep-lathep-phJHEP(2017)·552 citations
16. 16*

    Spontaneous Supersymmetry Breaking, Negative Metric and Vacuum Energy

    Taichiro Kugo🇯🇵

    The supersymmetric Nambu-Jona-Lasinio model proposed by Cheng, Dai, Faisel and Kong is re-analyzed by using an auxiliary superfield method in which a hidden local U(1) symmetry emerges. It is shown that, in the healthy field-space region where no negative metric particles appear, only SUSY preserving vacua can be realized in the weak coupling regime and a composite massive spin-1 supermultiplets appear as a result of spontaneous breaking of the hidden local U(1) symmetry. In the strong coupling regime, on the other hand, SUSY is dynamically broken, but it is always accompanied by negative metric particles.

    ↳ hep-thhep-ph1 citation
17. 17*

    Weighing neutrinos in dynamical dark energy models

    Xin Zhang🇨🇳

    We briefly review the recent results of constraining neutrino mass in dynamical dark energy models using cosmological observations and summarize the findings. (i) In dynamical dark energy models, compared to $\Lambda$CDM, the upper limit of $\sum m_{\nu }$ can become larger and can also become smaller. In the cases of phantom and early phantom (i.e., the quintom evolving from $w<-1$ to $w>-1$), the constraint on $\sum m_{\nu }$ becomes looser; but in the cases of quintessence and early quintessence (i.e., the quintom evolving from $w>-1$ to $w<-1$), the constraint on $\sum m_{\nu }$ becomes tighter. (ii) In the holographic dark energy (HDE) model, the tightest constraint on $\sum m_{\nu }$, i.e., $\sum m_{\nu }<0.105$ eV, is obtained, which is almost equal to the lower limit of $\sum m_{\nu }$ of IH case. Thus, it is of great interest to find that the future neutrino oscillation experiments would potentially offer a possible falsifying scheme for the HDE model. (iii) The mass splitting of neutrinos can influence the cosmological fits. We find that the NH case fits the current observations slightly better than the IH case, although the difference of ${\chi }^2$ of the two cases is still not significant enough to definitely distinguish the neutrino mass hierarchy.

    ↳ astro-ph.COgr-qchep-phSCPMA(2017)·48 citations
18. 18*

    Collective flow and hydrodynamics in large and small systems at the LHC

    Huichao Song🇨🇳 · You Zhou🇩🇰 · Katarina Gajdosova🇩🇰

    In this article, we briefly review the recent progress on collective flow and hydrodynamics in large and small systems at the Large Hadron Collider (LHC), which includes the following topics: extracting the QGP viscosity from the flow data, initial state fluctuations and final state correlations in 2.76 A TeV Pb--Pb collisions, correlations and collective flow in high energy p--Pb and p--p collisions.

    ↳ nucl-thhep-phnucl-exNucl.Sci.Tech.(2017)·155 citations
19. 19*

    Universal self-similar scaling of spatial Wilson loops out of equilibrium

    J. Berges🇩🇪 · M. Mace🇺🇸 · S. Schlichting🇺🇸

    We investigate strongly correlated non-Abelian plasmas out of equilibrium. Based on numerical simulations, we establish a self-similar scaling property for the time evolution of spatial Wilson loops that characterizes a universal state of matter far from equilibrium. Most remarkably, it exhibits a generalized area law which holds for sufficiently large ratio of spatial area and fractional power of time. Performing calculations also for the perturbative regime at higher momenta, we are able to characterize the full nonthermal scaling properties of SU(2) and SU(3) symmetric plasmas from short to large distance scales in terms of two independent universal exponents and associated scaling functions.

    ↳ hep-thhep-lathep-phPRL(2017)·27 citations
20. 20*

    Heavy and light flavor jet quenching at RHIC and LHC energies

    Shanshan Cao🇺🇸 · Tan Luo🇨🇳 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳

    The Linear Boltzmann Transport (LBT) model coupled to hydrodynamical background is extended to include transport of both light partons and heavy quarks through the quark-gluon plasma (QGP) in high-energy heavy-ion collisions. The LBT model includes both elastic and inelastic medium-interaction of both primary jet shower partons and thermal recoil partons within perturbative QCD (pQCD). It is shown to simultaneously describe the experimental data on heavy and light flavor hadron suppression in high-energy heavy-ion collisions for different centralities at RHIC and LHC energies. More detailed investigations within the LBT model illustrate the importance of both initial parton spectra and the shapes of fragmentation functions on the difference between the nuclear modifications of light and heavy flavor hadrons. The dependence of the jet quenching parameter $\hat{q}$ on medium temperature and jet flavor is quantitatively extracted.

    ↳ nucl-thhep-phnucl-exPLB(2018)·175 citations
21. 21*

    Screening masses in strong external magnetic fields

    Claudio Bonati🇮🇹 · Massimo D'Elia🇮🇹 · Marco Mariti🇮🇹 · Michele Mesiti🇮🇹 · Francesco Negro🇮🇹 · Andrea Rucci🇮🇹 · Francesco Sanfilippo🇮🇹

    We present results for the (color)magnetic and (color)electric screening masses of the Quark-Gluon Plasma in the presence of an external magnetic field. The screening masses are extracted from the correlators of Polyakov loops, determined by lattice QCD simulations at the physical point. We explore temperatures in the range $200\mathrm{MeV}\lesssim T\lesssim 330\mathrm{MeV}$ and magnetic field intensities up to $|e|B\sim 1.3{\mathrm{GeV}}^2$. We find that both screening masses are increasing functions of the magnetic field and that the dependence on $B$ becomes weaker for larger temperatures. In the case of the magnetic screening mass a slight anisotropy is also observable.

    ↳ hep-lathep-phPRD(2017)·53 citations
22. 22*

    Phases of New Physics in the BAO Spectrum

    Daniel Baumann🇳🇱 · Daniel Green🇺🇸 · Matias Zaldarriaga🇺🇸

    We show that the phase of the spectrum of baryon acoustic oscillations (BAO) is immune to the effects of nonlinear evolution. This suggests that any new physics that contributes to the initial phase of the BAO spectrum, such as extra light species in the early universe, can be extracted reliably at late times. We provide three arguments in support of our claim: First, we point out that a phase shift of the BAO spectrum maps to a characteristic sign change in the real space correlation function and that this feature cannot be generated or modified by nonlinear dynamics. Second, we confirm this intuition through an explicit computation, valid to all orders in cosmological perturbation theory. Finally, we provide a nonperturbative argument using general analytic properties of the linear response to the initial oscillations. Our result motivates measuring the phase of the BAO spectrum as a robust probe of new physics.

    ↳ astro-ph.COhep-phhep-thJCAP(2017)·101 citations
23. 23*

    The WKB approximation and tunneling in theories with non-canonical kinetic terms

    Mariana Carrillo Gonzalez🇺🇸 · Ali Masoumi🇺🇸 · Adam R. Solomon🇺🇸 · Mark Trodden🇺🇸

    Tunneling is a fascinating aspect of quantum mechanics that renders the local minima of a potential meta-stable, with important consequences for particle physics, for the early hot stage of the universe, and more speculatively, for the behavior of the putative multiverse. While this phenomenon has been studied extensively for systems which have canonical kinetic terms, many theories of fundamental physics contain fields with non-canonical kinetic structures. It is therefore desirable to have a detailed framework for calculating tunneling rates and initial states after tunneling for these theories. In this work, we present such a rigorous formulation and illustrate its use by applying it to a number of examples.

    ↳ hep-thhep-phPRD(2017)·1 citation

* 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.