Tue·Apr 17, 2018Tuesday·April 17, 2018

1. 01*

   Vacuum polarization corrections to ${\mu }^{+}{\mu }^{-}$ spectrum

   Wayne W. Repko🇺🇸

   The energy levels of the $n=1$ and $n=2$ bound states of the ${\mu }^{+}{\mu }^{-}$ atom (true muonium) are calculated starting from a previously derived potential that correctly describes positronium to order ${\alpha }^5$ supplemented by the known ${\alpha }^6$ contributions. All electron vacuum polarization corrections on the true muonium levels are computed to order ${\alpha }^6$ order. The second order perturbative contributions from all of the ${\alpha }^4$ and ${\alpha }^5$ terms in the potential are also included. Additional order ${\alpha }^6$ contributions from the two photon and three photon annihilation processes are included in the evaluation of the ground state ($1^3{S}_1-1^1{S}_0$) hyperfine splitting.

   hep-phPRD(2025)·0 citations
2. 02*

   Neutrino Oscillations in Dark Backgrounds

   Francesco Capozzi🇩🇪 · Ian M. Shoemaker🇺🇸 · Luca Vecchi🇨🇭

   We examine scenarios in which a dark sector (dark matter, dark radiation, or dark energy) couples to the active neutrinos. For light and weakly-coupled exotic sectors we find that scalar, vector, or tensor dark backgrounds may appreciably impact neutrino propagation while remaining practically invisible to all other phenomenological probes. The dark medium may induce small departures from the Standard Model predictions or even offer an alternative explanation of neutrino oscillations. While the propagation of neutrinos is affected in all experiments, atmospheric data currently represent the most promising probe of the new physics scale. We quantify the future sensitivity of the ORCA detector of KM3NeT and the IceCube experiment and find that all exotic effects can be constrained at the level of a few percent of the Earth matter potential, with couplings mediating $\mu$-neutrino transitions being most constrained. Long baseline experiments like DUNE may provide additional complementary information on the scale of the dark sector.

   hep-phhep-exJCAP(2018)·88 citations
3. 03*

   "Invisible" QCD axion rolling through the QCD phase transition

   Jihn E. Kim🇰🇷 · Se-Jin Kim

   Visible matter in the current Universe is a consequence of the phase transition of the strong force, quantum chromodynamics (QCD). This phase transition has occurred at the Universe temperature around $T_c\simeq 165$MeV while it was expanding. Strongly interacting matter particles are quarks above $T_c$, while they are pions, protons and neutrons below $T_c$. The spin degrees of freedom 37 in the quark and gluon phase just above $T_c$ are converted to 3 (pions) after the phase transition. This phase transition might have been achieved mostly at supercooled temperatures. The supercooling was provided by the expansion of the Universe. We obtain the effective bubble formation rate $\alpha (T)\approx 10^{4-5}$MeV and the completion temperature of the phase change (to the hadronic phase), $T_f\simeq 126$MeV. During the phase transition, the scale factor $R$ has increased by a factor of 2.4. This provides a key knowledge on the energy density of "invisible" QCD axion at the full hadronic-phase commencement temperature $T_f$, and allows for us to estimate the current energy density of cold dark matter composed of "invisible" QCD axions.

   hep-phastro-ph.COhep-latPLB(2018)·14 citations
4. 04*

   The next-to-next-to-leading order soft function for top quark pair production

   Guoxing Wang🇨🇳 · Xiaofeng Xu🇨🇳 · Li Lin Yang🇨🇳 · Hua Xing Zhu🇨🇳

   We present the first calculation of the next-to-next-to-leading order threshold soft function for top quark pair production at hadron colliders, with full velocity dependence of the massive top quarks. Our results are fully analytic, and can be entirely written in terms of generalized polylogarithms. The scale-dependence of our result coincides with the well-known two-loop anomalous dimension matrix including the three-parton correlations, which at the two-loop order only appear when more than one massive partons are involved in the scattering process. In the boosted limit, our result exhibits the expected factorization property of mass logarithms, which leads to a consistent extraction of the soft fragmentation function. The next-to-next-to-leading order soft function obtained in this paper is an important ingredient for threshold resummation at the next-to-next-to-next-to-leading logarithmic accuracy.

   hep-phhep-thJHEP(2018)·16 citations
5. 05*

   Probing bino-wino coannihilation dark matter under the neutrino floor at the LHC

   Guang Hua Duan🇨🇳 · Ken-ichi Hikasa🇯🇵 · Jie Ren🇨🇳 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳

   In the minimal supersymmetric standard model (MSSM) the bino-wino coannihilation provides a feasible way to accommodate the observed cosmological dark matter (DM) relic density. However, such a scenario usually predicts a very small DM-nucleon scattering cross section that is below the neutrino floor, and can not be tested by DM direct detection experiments. In this work, we investigate the discovery potential of this bino-wino co-annihilation region by searching for the soft dilepton events from the process $pp\to {\chi }_2^0(\to {\ell }^{+}{\ell }^{-}{\chi }_1^0){\chi }_1^{\pm }+jets$ at the LHC. We find that the mass of the wino-like ${\chi }_2^0$ can be probed up to about 310 (230) GeV at $2\sigma$ ($5\sigma$) level for an integrated luminosity $\mathcal{L}=300$ fb${}^{-1}$. In the future HL-LHC with 3000 fb${}^{-1}$ luminosity, the corresponding mass limits can be pushed up to 430 (330) GeV.

   hep-phhep-exPRD(2018)·36 citations
6. 06*

   Gluon GPDs and Exclusive Photoproduction of a Quarkonium in Forward Region

   Z.L. Cui🇨🇳 · M.C. Hu🇨🇳 · J.P. Ma🇨🇳

   Forward photoproduction of $J/\psi$ can be used to extract Generalized Parton Distributions(GPD's) of gluons. We analyze the process at twist-3 level and study relevant classifications of twist-3 gluon GPD's. At leading power or twist-2 level the produced $J/\psi$ is transversely polarized. We find that at twist-3 the produced $J/\psi$ is longitudinally polarized. Our study shows that in high energy limit the twist-3 amplitude is only suppressed by the inverse power of the heavy quark mass relatively to the twist-2 amplitude. This indicates that the power correction to the cross-section of unpolarized $J/\psi$ can have a sizeable effect. We have also derived the amplitude of the production of $h_c$ at twist-3, but the result contains end-point singularities. The production of other quarkonia has been briefly discussed.

   hep-phhep-exEPJC(2019)·16 citations
7. 07*

   In depth analysis of the combined HERA data in the dipole models with and without saturation

   Heikki Mäntysaari🇫🇮 · Pia Zurita🇺🇸

   We present an updated impact parameter dependent saturation model (IPsat) determined trough a fit to the combined HERA I and I+II reduced cross section data. The same HERA data are used to fit the linearized (IPnonsat) version of the applied dipole amplitude, which makes it possible to estimate the magnitude of the saturation effects in various experiments. We find that both parametrizations provide comparable descriptions of the considered data when an effective confinement scale dynamics is incorporated with quark masses. Moreover, it is possible to consistently determine the light and charm quark masses. The role of potentially non-perturbatively large dipoles is examined in detail, with the result that, especially in case of the structure function $F_2$, their contribution is numerically significant. Potential to discriminate between the two models in future $e+p$ and $e+A$ experiments is also illustrated.

   hep-phnucl-thPRD(2018)·94 citations
8. 08*

   Hydrogen spin oscillations in a background of axions and the 21-cm brightness temperature

   G. Lambiase🇮🇹 · S. Mohanty🇮🇳

   The 21-cm line signal arising from the hyperfine interaction in hydrogen has an important role in cosmology and provides a unique method for probing of the universe prior to the star formation era. We propose that the spin flip of Hydrogen by the coherent emission/absorption of axions causes a lowering of their spin temperature and can explain the stronger than expected absorption of 21-cm light reported by the EDGES collaboration. We find the analogy of axion interaction with the two level HI with the Jaynes-Cummings model of a two level atom in a cavity and we derive the spin flip frequency in this formalism and show that the coherent oscillations frequency $\Omega \propto 1/f_a$ in contrast with the incoherent transitions between the HI hyperfine levels where the transition rates $\propto 1/f_a^2$. The axion emission and absorption rates are equal but the spin temperature is still lowered due to different selection rules for the spin flip transitions compared to the photon process. We show that the axion process goes in the right direction for explaining the EDGES observation. For this mechanism to work we require a coherent field of relativistic axions with energy $E_{\nu }$ peaked at the 21-cm spin-flip energy. Such a coherent background of relativistic axions can arise from the decay of cosmic strings if the decay takes place in the electroweak era.

   hep-phMNRAS(2020)·28 citations
9. 09*

   Pinning down Anomalous $WW\gamma$ Couplings at the LHC

   Disha Bhatia🇮🇳 · Ushoshi Maitra🇮🇳 · Sreerup Raychaudhuri🇮🇳

   We make a careful analysis of $W^{\pm }\gamma$ production at the LHC, identifying the $W^{\pm }$ through leptonic decays, with a view to exploring the sensitivity of the machine to anomalous $CP$-conserving $WW\gamma$ interactions. All the available kinematic variables are used, but we find that the most useful one is the opening angle in the transverse plane between the decay products of the $W^{\pm }$. It is shown that even a simple-minded analysis using this variable can lead to a much greater sensitivity at the LHC than the current constraints on the relevant parameters.

   hep-phPRD(2019)·15 citations
10. 10*

    Sterile neutrinos as a possible explanation for the upward air shower events at ANITA

    Guo-yuan Huang🇨🇳

    The ANITA experiment has observed two unusual upgoing air shower events which are consistent with the $\tau$-lepton decay origin. However, these events are in contradiction with the standard neutrino-matter interaction models as well as the $\mathrm{EeV}$ diffuse neutrino flux limits set by the IceCube and the cosmic ray facilities like AUGER. In this paper, we have reinvestigated the possibility of using sterile neutrino hypothesis to explain the ANITA anomalous events. The diffuse flux of the sterile neutrinos is less constrained by the IceCube and AUGER experiments due to the small active-sterile mixing suppression. The quantum decoherence effect should be included for describing the neutrino flux propagating in the Earth matter, because the interactions between neutrinos and the Earth matter are very strong at the EeV scale. After several experimental approximations, we show that the ANITA anomaly itself is able to be explained by the sterile neutrino origin, but we also predict that the IceCube observatory should have more events than ANITA. It makes the sterile neutrino origin very unlikely to account for both of them simultaneously. A more solid conclusion can be drawn by the dedicated ANITA signal simulations.

    hep-phPRD(2018)·53 citations
11. 11*

    Thermodynamical consistency of quasiparticle model at finite baryon density

    Hong-Hao Ma🇧🇷 · Kai Lin🇧🇷 · Wei-Liang Qian🇧🇷 · Yogiro Hama🇧🇷 · Takeshi Kodama🇧🇷

    In this work, we revisit the thermodynamical self-consistency of the quasiparticle model with the finite baryon chemical potential adjusted to lattice QCD calculations. Here, we investigate the possibility that the effective quasiparticle mass is also a function of its momentum, $k$, in addition to temperature $T$ and chemical potential $\mu$. It is found that the thermodynamic consistency can be expressed in terms of an integro-differential equation concerning $k$, $T$, and $\mu$. We further discuss two special solutions, both can be viewed as sufficient condition for the thermodynamical consistency, while expressed in terms of a particle differential equation. The first case is shown to be equivalent to those previously discussed by Peshier et al. The second one, obtained through an ad hoc assumption, is an intrinsically different solution where the particle mass is momentum dependent. These equations can be solved by using boundary condition determined by the lattice QCD data at vanishing baryon chemical potential. By numerical calculations, we show that both solutions can reasonably reproduce the recent lattice QCD results of the Wuppertal-Budapest and HotQCD Collaborations, and in particular, those concerning finite baryon density. Possible implications are discussed.

    hep-phPRC(2019)·5 citations
12. 12*

    Mass dependence of vector meson photoproduction off protons and nuclei within the energy-dependent hot-spot model

    J. Cepila🇨🇿 · J. G. Contreras🇨🇿 · M.Krelina🇨🇱 · J. D. Tapia Takaki🇺🇸

    We study the photoproduction of vector mesons off proton and off nuclear targets. We work within the colour dipole model in an approach that includes subnucleon degrees of freedom, so-called hot spots, whose positions in the impact-parameter plane change event-by-event. The key feature of our model is that the number of hot spots depends on the energy of the photon--target interaction. Predictions are presented for exclusive and dissociative production of ${\rho }^0$, $J/\psi$, and ${\rm Y}(1S)$ off protons, as well as for coherent and incoherent photoproduction of ${\rho }^0$ off nuclear targets, where Xe, Au, and Pb nuclei are considered. We find that the mass dependence of dissociative production off protons as a function of the energy of the interaction provides a further handle to search for saturation effects at HERA, the LHC and future colliders. We also find that the coherent photonuclear production of ${\rho }^0$ is sensitive to fluctuations in the subnucleon degrees of freedom at RHIC and LHC energies.

    hep-phNPB(2018)·51 citations
13. 13*

    Deep inelastic $e-\tau$ and $\mu -\tau$ conversion in the NA64 experiment at the CERN SPS

    Sergei Gninenko🇷🇺 · Sergey Kovalenko🇨🇱 · Serguei Kuleshov🇨🇱 · Valery E. Lyubovitskij🇩🇪 · Alexey S. Zhevlakov🇷🇺

    We study the Lepton Flavor Violating (LFV) $e(\mu )-\tau$ conversion in Deep Inelastic Scattering (DIS) of electron (muon) on fixed-target nuclei. Our model-independent analysis is based on the set of the low-energy effective four-fermion LFV operators composed of leptons and quarks with the corresponding mass scales ${\Lambda }_k$ for each operator. Using the estimated sensitivity of the search for this LFV process in events with large missing energy in the NA64 experiment at the CERN SPS, we derive lower limits for ${\Lambda }_k$ and compared them with the corresponding limits existing in the literature. We show that the DIS $e(\mu )-\tau$ conversion is able to provide a plenty of new limits as yet non-existing in the literature. We also analyzed the energy spectrum of the final-state $\tau$ and discussed viability of the observation of this process in the NA64 experiment and ones akin to it. The case of polarized beams and targets is also discussed.

    hep-phPRD(2018)·45 citations
14. 14*

    Detailed Study of the Decay Lambda_b --> Lambda_c tau {\bar \nu}_{\tau}

    E. Di Salvo🇫🇷 · F. Fontanelli🇮🇹 · Z.J. Ajaltouni🇫🇷

    We examine in detail the semi-leptonic decay ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$, which may confirm previous hints, from the analogous $B$ decay, of a new physics beyond the standard model. First of all, starting from rather general assumptions, we predict the partial width of the decay. Then we analyze the effects of five possible new physics interactions, adopting in each case five different form factors. In particular, for each term beyond the standard model, we find some constraints on the strength and phase of the coupling, which we combine with those found by other authors in analyzing the analogous semi-leptonic decays of $B$. Our analysis involves some dimensionless quantities, substantially independent of the form factor, but which, owing to the constraints, turn out to be strongly sensitive to the kind of non-standard interaction. We also introduce a criterion thanks to which one can discriminate among the various new physics terms: the left-handed current and the two-higgs-doublet model appear privileged, with a neat preference for the former interaction. Lastly, we suggest a differential observable that could, in principle, help to distinguish between the two cases.

    hep-phInt.J.Mod.Phys.A(2018)·43 citations
15. 15*

    A strategy for a simultaneous measurement of $CP$ violation parameters related to the $CKM$ angle $\gamma$ in multiple $B$ meson decay channels

    Jordi Garra Ticó🇬🇧

    Several methods exist to measure $CP$ violation observables related to the $CKM$ angle $\gamma$. These observables are different for every $B$ meson decay channel. However, the information they contain on $\gamma$ is encoded in a similar way for all of them. This paper describes a strategy for a simultaneous measurement including several $B$ meson decay channels, while taking into account any possible correlations between them.

    hep-ph8 citations
16. 16*

    Constraining top quark flavor violation and dipole moments through three and four top quark productions at the LHC

    Malihe Malekhosseini🇮🇷 · Mehrdad Ghominejad🇮🇷 · Hamzeh Khanpour🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

    In this paper, we examine the sensitivity of the three-top quark production at the LHC to the top quark flavor-changing neutral currents (FCNC) as well as the sensitivity of the four-top production to the strong and weak dipole moments of the top quark. Upper limits at $95\%$ CL on the branching fractions of $\mathcal{B}(t\to qX)$, where $X=g,Z,\gamma ,H$ and $q=u,c$, are set by performing an analysis on three-top events in the same-sign dilepton channel. We consider the main sources of the background processes and a realistic detector simulation is performed at the center-of-mass energy of 14 TeV. In the second part of this work, based on the recent upper limits which have been set on the four-top quark cross section by the ATLAS and CMS collaborations from 13 TeV data, we constrain the top quark strong and weak dipole moments. The bounds on the top quark dipole moments are presented using the future LHC prospects for four-top quark cross section measurement.

    hep-phhep-exPRD(2018)·25 citations
17. 17*

    Three-loop MSSM Higgs-Boson Mass Predictions and Regularization by Dimensional Reduction

    Dominik Stöckinger🇩🇪 · Josua Unger🇩🇪

    The evaluation of three-loop contributions to the MSSM Higgs-boson mass is considered at the orders enhanced by the strong gauge coupling and top or bottom Yukawa couplings, i.e. at the orders $O({\alpha }_{t,b}{\alpha }_s^2,{\alpha }_{t,b}^2{\alpha }_s,{\alpha }_{t,b}^3)$. We prove that regularization by dimensional reduction preserves supersymmetry at the required level. Thus generating counterterms by multiplicative renormalization is correct. Technically, we extend a previous two-loop analysis to the three-loop level. The extension covers not only the genuine three-loop Higgs potential counterterms but also a large sector of two-loop counterterms, required for subrenormalization.

    hep-phNPB(2018)·29 citations
18. 18*

    Dijet production in diffractive deep-inelastic scattering in next-to-next-to-leading order QCD

    D. Britzger🇩🇪 · J. Currie🇬🇧 · T. Gehrmann🇨🇭 · A. Huss🇨🇭 · J. Niehues🇬🇧 · R. Žlebčík🇩🇪

    Hard processes in diffractive deep-inelastic scattering can be described by a factorisation into parton-level subprocesses and diffractive parton distributions. In this framework, cross sections for inclusive dijet production in diffractive deep-inelastic electron-proton scattering (DIS) are computed to next-to-next-to-leading order (NNLO) QCD accuracy and compared to a comprehensive selection of data. Predictions for the total cross sections, 39 single-differential and four double-differential distributions for six measurements at HERA by the H1 and ZEUS collaborations are calculated. In the studied kinematical range, the NNLO corrections are found to be sizeable and positive. The NNLO predictions typically exceed the data, while the kinematical shape of the data is described better at NNLO than at next-to-leading order (NLO). A significant reduction of the scale uncertainty is achieved in comparison to NLO predictions. Our results use the currently available NLO diffractive parton distributions, and the discrepancy in normalisation highlights the need for a consistent determination of these distributions at NNLO accuracy.

    hep-phhep-exEPJC(2018)·23 citations
19. 19*

    Effective Field Theory with Nambu-Goldstone Modes

    Antonio Pich🇪🇸

    These lectures provide an introduction to the low-energy dynamics of Nambu-Goldstone fields, associated with some spontaneous (or dynamical) symmetry breaking, using the powerful methods of effective field theory. The generic symmetry properties of these massless modes are described in detail and two very relevant phenomenological applications are worked out: chiral perturbation theory, the low-energy effective theory of QCD, and the (non-linear) electroweak effective theory. The similarities and differences between these two effective theories are emphasized, and their current status is reviewed. Special attention is given to the short-distance dynamical information encoded in the low-energy couplings of the effective Lagrangians. The successful methods developed in QCD could help us to uncover fingerprints of new physics scales from future measurements of the electroweak effective theory couplings.

    hep-phhep-thLes Houches Lect.Notes(2020)·78 citations
20. 20*

    Time-dependent Ginzburg-Landau approach to the dynamics of inhomogeneous chiral condensates in a nonlocal Nambu--Jona-Lasinio model

    Juan Pablo Carlomagno🇦🇷 · Gastão Krein🇧🇷

    We study the dynamics of inhomogeneous scalar and pseudoscalar chiral order parameters within the framework of the time-dependent Ginzburg-Landau equations. We utilize a nonlocal chiral quark model to obtain the phase diagram of the model as function of temperature and baryon chemical potential and study the formation of metastable spatial domains of matter where the order parameters acquire a spatial modulation in the course their dynamical evolution. We found that, before reaching the expected equilibrium homogeneous state, both scalar and pseudoscalar chiral condensates go through long-lived metastable inhomogeneous structures. For different initial configurations of the order parameters, the lifetimes of the inhomogeneous structures are compared to timescales in a relativistic heavy-ion collision.

    hep-phPRD(2018)·6 citations
21. 21*

    Neutrino Physics and Leptonic Weak Basis Invariants

    M. N. Rebelo🇵🇹

    In this talk we present a powerful tool applied to the study of Leptonic Physics. This tool is based on the construction of Weak Basis invariant relations associated to different properties of leptonic models. The rationale behind these constructions is the fact that fermion mass matrices related through weak basis transformations look different but lead to the same physics. Such invariants can be built, for instance, with the aim to test leptonic models for different types of CP violation. These invariants are also relevant beyond such tests and have been applied to the study of implications from zero textures appearing in the leptonic mass matrices. In this case an important question is, how can a flavour model corresponding to a set of texture zeros be recognised, when written in a different weak basis, where the zeros are not explicitly present. Another important application is the construction of invariants sensitive to the neutrino mass ordering and the ${\theta }_{23}$ octant.

    hep-ph2 citations
22. 22*

    Strongly First-Order Phase Transition in Real Singlet Scalar Dark Matter Model

    Karim Ghorbani🇮🇷 · Parsa Hossein Ghorbani🇺🇸

    The extension of the standard model by a real gauge singlet scalar is the simplest but the most studied model with sometimes controversial ideas on the ability of the model to address the dark matter and the electroweak phase transition issues simultaneously. For this model, we obtain analytically slightly different conditions for strongly first-order electroweak phase transition and apply that in computation of the dark matter relic density where the real scalar plays the role of the dark matter particle. We show that the scalar in this model before imposing the invisible Higgs decay constraint, can be responsible for all or part of the dark matter abundance, while at the same time gives rise to a strongly first-order electroweak phase transition required for the baryogenesis. When the constraints from the direct detection experiments such as XENON100 or LUX/XENON1t are considered, the model is excluded completely.

    hep-phJ.Phys.G(2020)·42 citations
23. 23*

    Non-Standard Neutrino Interactions in a Modified $\nu$2HDM

    Ujjal Kumar Dey🇮🇳 · Newton Nath🇨🇳 · Soumya Sadhukhan🇮🇳

    In the traditional neutrinophilic two-Higgs doublet model ($\nu$2HDM), there is no non-standard neutrino interaction (NSI) as the interactions between the Standard Model fermions with neutrinos are negligibly small due to the tiny mixing of the two scalar doublets. In this work, we propose that if $\nu$2HDM is modified by considering the right-handed electron, $e_R$ is negatively charged under a global $U(1)$-symmetry then one can generate significant amount of NSI along with the tiny Dirac neutrino mass. Depending on different constraints from the LEP experiment, tree level lepton flavor violating processes, big-bang neucleosynthesis etc., we observe that this model significantly restricts the range of permissible NSI parameters, putting a strict upper bound on different NSIs. Furthermore, considering these model-dependent NSIs, we study their impact on the next-generation superbeam experiment, DUNE. We present a detailed discussion on the mass hierarchy sensitivity and the CP-violation discovery study considering the impact of both diagonal as well as off-diagonal NSIs.

    hep-phPRD(2018)·33 citations
24. 24*

    Two-field cosmological phase transitions and gravitational waves in the singlet Majoron model

    Youping Wan🇨🇳 · Batool Imtiaz🇨🇳 · Yi-Fu Cai🇨🇳

    In the singlet Majoron model, we study cosmological phase transitions (PTs) and their resulting gravitational waves (GWs), in the two-field phase space, without freezing any of the field directions. We first calculate the effective potential, at one loop and at finite temperature, of the Standard Model Higgs doublet together with one extra Higgs singlet. We make use of the public available Python package CosmoTransitions to simulate the two-dimensional cosmological PTs and evaluate the gravitational waves generated by first-order PTs. With the full 2D simulation, we are able not only to confirm the PTs' properties previously discussed in the literature, but also we find new patterns, such as strong first-order PTs tunneling from a vacuum located on one axis to another vacuum located on the second axis. The two-field phase space analysis presents a richer panel of cosmological PT patterns compared to analysis with a single-field approximation. The PTGW amplitudes turn out to be out of the reach for the space-borne gravitational wave interferometers such as LISA, DECIGO, BBO, TAIJI and TianQin when constraints from colliders physics are taken into account.

    hep-phgr-qcEPJC(2019)·28 citations
25. 25*

    New physics vs new paradigms: distinguishing CPT violation from NSI

    Gabriela Barenboim🇪🇸 · Christoph Andreas Ternes🇪🇸 · Mariam Tórtola🇪🇸

    Our way of describing Nature is based on local relativistic quantum field theories, and then CPT symmetry, a natural consequence of Lorentz invariance, locality and hermiticity of the Hamiltonian, is one of the few if not the only prediction that all of them share. Therefore, testing CPT invariance does not test a particular model but the whole paradigm. Current and future long baseline experiments will assess the status of CPT in the neutrino sector at an unprecedented level and thus its distinction from similar experimental signatures arising from non-standard interactions is imperative. Whether the whole paradigm is at stake or just the standard model of neutrinos crucially depends on that.

    hep-phhep-exEPJC(2019)·26 citations
26. 26*

    $B$-decay anomalies and scalar leptoquarks in unified Pati-Salam models from noncommutative geometry

    Ufuk Aydemir🇨🇳 · Djordje Minic🇺🇸 · Chen Sun🇨🇳 · Tatsu Takeuchi🇺🇸

    Motivated by possible scalar-leptoquark explanations of the recently reported $B$-decay anomalies, we investigate whether the required leptoquarks can be accommodated within models based on noncommutative geometry (NCG). The models considered have the gauge structure of Pati-Salam models, $SU(4)\times SU(2{)}_L\times SU(2{)}_R$, with gauge coupling unification at a single scale. In one of the models, we find a unique scalar leptoquark with quantum numbers $(3,1,-\frac{1}{3}{)}_{321}$, originating from a complex multiplet $(6,1,1{)}_{422}$, which can potentially explain the $B$-decay anomalies if its mass is on the order of a few TeV. The unification of couplings can be realized with the inclusion of a single step of intermediate symmetry breaking. The scalar leptoquark under consideration does not contribute to proton decay due to the absence of diquark couplings, as dictated by the underlying noncommutative geometry.

    hep-phhep-thJHEP(2018)·39 citations
27. 27*

    Analytic inclusion of the scale dependence of the anomalous dimension matrix in Standard Model Effective Theory

    Andrzej J. Buras🇩🇪 · Martin Jung🇩🇪

    The renormalization group equations (RGEs) in Standard Model effective theory are usually either solved analytically, neglecting the scale dependence of gauge and Yukawa couplings, or numerically without such approximations. We present analytic solutions of RGEs that take into account the dominant scale dependence of the anomalous-dimension matrix due to the running of the QCD coupling and of the top-Yukawa coupling. We consider first the case for which a given operator is generated directly through mixing with the parent operator whose Wilson coefficient is non-vanishing at the new physics scale. Subsequently we consider the case of two-step running, in which two operators do not mix directly, but only via a third mediator operator. We generalize these solutions to an arbitrary number of operators and show how even in this case analytic solutions can be obtained.

    hep-phJHEP(2018)·20 citations
28. 28*

    Systematic Errors in General Spin Precession in Storage Ring

    Takeshi Fukuyama🇯🇵

    We analyse the systematic errors on the spin precession of particles in the storage ring, especially in the muon g-2/EDM project. There particles have both anomalous magnetic moments (g-2) and elctric dipole moments(EDM), and their positions and velocity directions have both $O(10^{-3}-10^{-4})\equiv O(ϵ)$ extensions. In order to measure these dipole moments up to $0.1$ppm or more we determine the precession frequency up to $O({ϵ}^2)$. Our analytical formulation includes the Farley's pitch correction in the special case and can be applied to more general experimental setups.

    hep-phhep-exPLB(2018)·0 citations
29. 29*

    Infrared Resummation for Biased Tracers in Redshift Space

    Mikhail M. Ivanov🇺🇸 · Sergey Sibiryakov🇨🇭

    We incorporate the effects of redshift space distortions and non-linear bias in time-sliced perturbation theory (TSPT). This is done via a new method that allows to map cosmological correlation functions from real to redshift space. This mapping preserves a transparent infrared (IR) structure of the theory and provides us with an efficient tool to study non-linear infrared effects altering the pattern of baryon acoustic oscillations (BAO) in redshift space. We give an accurate description of the BAO by means of a systematic resummation of Feynman diagrams guided by well-defined power counting rules. This establishes IR resummation within TSPT as a robust and complete procedure and provides a consistent theoretical model for the BAO feature in the statistics of biased tracers in redshift space.

    ↳ astro-ph.COhep-phhep-thJCAP(2018)·162 citations
30. 30*

    Gravitational wave asteroseismology limits from low density nuclear matter and perturbative QCD

    C. Vásquez Flores🇧🇷 · G. Lugones🇧🇷

    We investigate the fundamental mode of non-radial oscillations of non-rotating compact stars in general relativity using a set of equations of state (EOS) connecting state-of-the-art calculations at low and high densities. Specifically, a low density model based on the chiral effective field theory (EFT) and high density results based on perturbative Quantum Chromodynamics (QCD) are matched through different interpolating polytropes fulfilling thermodynamic stability and subluminality of the speed of sound, together with the additional requirement that the equations of state support a two solar mass star. We employ three representative models (EOS I, II and III) presented in Ref. [1] such that EOS I gives the minimum stellar radius, EOS II the maximum stellar mass, and EOS III the maximum stellar radius. Using this family of equations of state, we find that the frequency and the damping time of the $f$-mode are constrained within narrow quite model-independent windows. We also analyze some proposed empirical relations that describe the $f$-mode properties in terms of the average density and the compactness of the neutron star. We discuss the stringency of these constrains and the possible role of physical effects that cannot be encoded in a mere interpolation between low and high density EOSs.

    ↳ astro-ph.HEgr-qchep-phJCAP(2018)·16 citations
31. 31*

    Generalized Uncertainty Principle, Black Holes, and White Dwarfs: A Tale of Two Infinities

    Yen Chin Ong🇨🇳

    It is often argued that quantum gravitational correction to the Heisenberg's uncertainty principle leads to, among other things, a black hole remnant with finite temperature. However, such a generalized uncertainty principle also seemingly removes the Chandrasekhar limit, i.e., it permits white dwarfs to be arbitrarily large, which is at odds with astrophysical observations. We show that this problem can be resolved if the parameter in the generalized uncertainty principle is negative. We also discuss the Planck scale physics of such a model.

    ↳ gr-qchep-phhep-thJCAP(2018)·131 citations
32. 32*

    Statistical and systematical errors in analyses of separate experimental data sets in high energy physics

    R. Orava🇫🇮 · O.V. Selyugin🇷🇺

    Different ways of extracting parameters of interest from combined data sets of separate experiments are investigated accounting for the systematic errors. It is shown, that the frequentist approach may yield larger ${\chi }^2$ values when compared to the Bayesian approach, where the systematic errors have a Gaussian distributed prior calculated in quadrature. The former leads to a better estimation of the parameters. A maximum-likelihood method, applied to different "gedanken" and real LHC data, is presented. The results allow to choose an optimal approach for obtaining the fit based model parameters.

    ↳ hep-exhep-phphysics.data-an5 citations
33. 33*

    Non-resistive dissipative magnetohydrodynamics from the Boltzmann equation in the 14-moment approximation

    Gabriel S. Denicol🇧🇷 · Xu-Guang Huang🇨🇳 · Etele Molnár🇩🇪 · Gustavo M. Monteiro🇧🇷 · Harri Niemi🇩🇪 · Jorge Noronha🇧🇷 · Dirk H. Rischke🇩🇪 · Qun Wang🇨🇳

    We derive the equations of motion of relativistic, non-resistive, second-order dissipative magnetohydrodynamics from the Boltzmann equation using the method of moments. We assume the fluid to be composed of a single type of point-like particles with vanishing dipole moment or spin, so that the fluid has vanishing magnetization and polarization. In a first approximation, we assume the fluid to be non-resistive, which allows to express the electric field in terms of the magnetic field. We derive equations of motion for the irreducible moments of the deviation of the single-particle distribution function from local thermodynamical equilibrium. We analyze the Navier-Stokes limit of these equations, reproducing previous results for the structure of the first-order transport coefficients. Finally, we truncate the system of equations for the irreducible moments using the 14-moment approximation, deriving the equations of motion of relativistic, non-resistive, second-order dissipative magnetohydrodynamics. We also give expressions for the new transport coefficients appearing due to the coupling of the magnetic field to the dissipative quantities.

    ↳ nucl-thhep-phphysics.flu-dynPRD(2018)·103 citations
34. 34*

    Monte Carlo Glauber model with meson cloud: predictions for 5.44 TeV Xe+Xe collisions

    B.G. Zakharov🇷🇺

    We study, within the Monte-Carlo Glauber model, centrality dependence of the midrapidity charged multiplicity density $d{N}_{ch}/d\eta$ and of the anisotropy coefficients ${\epsilon }_{2,3}$ in Pb+Pb collisions at $\sqrt{s}=5.02$ TeV and in Xe+Xe collisions at $\sqrt{s}=5.44$ TeV. Calculations are performed for versions with and without nucleon meson cloud. The fraction of the binary collisions, $\alpha$, has been fitted to the data on $d{N}_{ch}/d\eta$ in Pb+Pb collisions. We obtain $\alpha \approx 0.09(0.13)$ with (without) meson cloud. The effect of meson cloud on the $d{N}_{ch}/d\eta$ is relatively small. For Xe+Xe collisions for $0$-$5$\% centrality bin we obtain $d{N}_{ch}/d\eta \approx 1149$ and $1134$ with and without meson cloud, respectively. We obtain ${\epsilon }_2(\text{mbox}Xe)/{\epsilon }_2(\text{mbox}Pb)\sim 1.45$ for most central collisions, and ${\epsilon }_2(\text{mbox}Xe)/{\epsilon }_2(\text{mbox}Pb)$ close to unity at $c\gtrsim 20$\%. We find a noticeable increase of the eccentricity in Xe+Xe collisions at small centralities due to the prolate shape of the Xe nucleus. The triangularity in Xe+Xe collisions is bigger than in Pb+Pb collisions at $c\lesssim 70$\%. We obtain ${\epsilon }_3(\text{mbox}Xe)/{\epsilon }_3(\text{mbox}Pb)\sim 1.3$ at $c\lesssim 1$\%.

    ↳ nucl-thhep-phEPJC(2018)·14 citations
35. 35*

    Simulation study of elliptic flow of charged hadrons produced in Au + Au collisions at the Facility for Antiproton and Ion Research

    Soumya Sarkar🇮🇳 · Provash Mali🇮🇳 · Amitabha Mukhopadhyay🇮🇳

    Centrality and system geometry dependence of azimuthal anisotropy of charged hadrons measured in terms of the elliptic flow parameter are investigated using Au+Au event samples at incident beam energy $20$A GeV and $40$A GeV generated by Ultrarelativistic Quantum Molecular Dynamics and A Multiphase Transport models. The Monte Carlo Glauber model is employed to estimate the eccentricity of the overlapping zone at an early stage of the collisions. Anisotropies present both in the particle multiplicity distribution and in the kinetic radial expansion are examined by using standard statistical and phenomenological methods. In the context of upcoming Compressed Baryonic Matter experiment to be held at the Facility for Antiproton and Ion Research, the present set of simulated results provide us not only with an opportunity to examine the expected collective behavior of hadronic matter at high baryon density and moderate temperature environment, but when compared with similar results obtained from Relativistic Heavy Ion Collider and Large Hadron Collider experiments, they also allow us to investigate how anisotropy of hadronic matter may differ or agree with its low baryon density and high temperature counterpart.

    ↳ nucl-thhep-phPRC(2017)·15 citations
36. 36*

    Azimuthal anisotropy in particle distribution in A Multi-phase Transport Model

    Soumya Sarkar🇮🇳 · Provash Mali🇮🇳 · Amitabha Mukhopadhyay🇮🇳

    Anisotropic flow of hadronic matter is considered as a sensitive tool to detect the early stage dynamics of high-energy heavy-ion collisions. Taking the event by event fluctuations of the collision geometry into account, the elliptic flow parameter and the triangular flow parameter derived from the azimuthal distribution of produced hadrons, are investigated within the framework of a multiphase transport (AMPT) model, at a collision energy that in near future will typically be available at the Facility for Antiproton and Ion Research. The dependence of elliptic and triangular flow parameters on initial fluctuations, on parton scattering cross-sections, their mass ordering on different hadron species and on the constituent quark number scaling are examined. The AMPT simulation can not exactly match the elliptic flow results on Pb + Pb collision at 40A GeV of the NA49 experiment. The simulation results presented in this work are expected to provide us with an insight to study flow properties at high baryonic density but moderate temperature, and also with an opportunity to compare similar results available from RHIC and LHC experiments.

    ↳ nucl-thhep-phPRC(2017)·8 citations
37. 37*

    $\text{Tr}(F^3)$ supersymmetric form factors and maximal transcendentality Part I: $\mathcal{N}=4$ super Yang-Mills

    Andreas Brandhuber🇬🇧 · Martyna Kostacinska🇬🇧 · Brenda Penante🇨🇭 · Gabriele Travaglini🇬🇧

    In the large top-mass limit, Higgs plus multi-gluon amplitudes in QCD can be computed using an effective field theory. This approach turns the computation of such amplitudes into that of form factors of operators of increasing classical dimension. In this paper we focus on the first finite top-mass correction, arising from the operator $\mathrm{Tr}(F^3)$, up to two loops and three gluons. Setting up the calculation in the maximally supersymmetric theory requires identification of an appropriate supersymmetric completion of $\mathrm{Tr}(F^3)$, which we recognise as a descendant of the Konishi operator. We provide detailed computations for both this operator and the component operator $\mathrm{Tr}(F^3)$, preparing the ground for the calculation in $\mathcal{N}<4$, to be detailed in a companion paper. Our results for both operators are expressed in terms of a few universal functions of transcendental degree four and below, some of which have appeared in other contexts, hinting at universality of such quantities. An important feature of the result is a delicate cancellation of unphysical poles appearing in soft/collinear limits of the remainders which links terms of different transcendentality. Our calculation provides another example of the principle of maximal transcendentality for observables with non-trivial kinematic dependence.

    ↳ hep-thhep-phJHEP(2018)·45 citations
38. 38*

    Diffusive dynamics of critical fluctuations near the QCD critical point

    Marlene Nahrgang (SUBATECH, Nantes)🇫🇷 · Marcus Bluhm (Wroclaw U.)🇵🇱 · Thomas Schaefer (North Carolina State U.)🇺🇸 · Steffen A. Bass (Duke U.)🇺🇸

    A quantitatively reliable theoretical description of the dynamics of fluctuations in non-equilibrium is indispensable in the experimental search for the QCD critical point by means of ultra-relativistic heavy-ion collisions. In this work we consider the fluctuations of the net-baryon density which becomes the slow, critical mode near the critical point. Due to net-baryon number conservation the dynamics is described by the fluid dynamical diffusion equation, which we extend to contain a white noise stochastic current. Including nonlinear couplings from the 3d Ising model universality class in the free energy functional, we solve the fully interacting theory in a finite size system. We observe that purely Gaussian white noise generates non-Gaussian fluctuations, but finite size effects and exact net-baryon number conservation lead to significant deviations from the expected behavior in equilibrated systems. In particular the skewness shows a qualitative deviation from infinite volume expectations. With this benchmark established we study the real-time dynamics of the fluctuations. We recover the expected dynamical scaling behavior and observe retardation effects and the impact of critical slowing down near the pseudo-critical temperature.

    ↳ nucl-thhep-phPRD(2019)·131 citations
39. 39*

    Scaling behavior of anisotropic flow harmonics in the far from equilibrium regime

    Nicolas Borghini🇩🇪 · Steffen Feld🇩🇪 · Nina Kersting🇩🇪

    We consider the development of anisotropic flow in an expanding system of particles undergoing very few rescatterings, using a kinetic-theoretical description with a nonlinear collision term. We derive the scaling behaviors of the harmonic coefficients $v_n$ with the initial-state eccentricities and the mean number of rescatterings, and argue that hexagonal flow $v_6$ should follow a nontrivial behavior, different from that of the lower harmonics. Our findings should be observable in experimental data for small systems.

    ↳ nucl-thhep-phnucl-exEPJC(2018)·28 citations
40. 40*

    Searching for light from a dark matter clump

    Tathagata Ghosh🇺🇸 · Jason Kumar🇺🇸 · Danny Marfatia🇺🇸 · Pearl Sandick🇺🇸

    The DAMPE experiment has recently reported an electron spectrum that can be explained by dark matter annihilation into charged lepton pairs in a nearby dark matter clump. The accompanying bremsstrahlung may yield a gamma-ray excess with a known spectral shape that extends over an angular scale of $O(10^{\circ })$. We show that such an excess is not present in Fermi-LAT data.

    ↳ astro-ph.HEastro-ph.COhep-exhep-phJCAP(2018)·7 citations
41. 41*

    MOND from a brane-world picture

    Mordehai Milgrom🇮🇱

    I describe a heuristic model where MOND dynamics emerge in a universe viewed as a nearly spherical brane embedded in a higher-dimensional flat space. The brane, described by $\xi (\Omega )$, is of density $\sigma$ ($\xi$ and $\Omega$ are the radial and angular coordinates in the embedding space). The brane and matter -- confined to the brane and of density $\rho (\Omega )\ll \sigma$ -- are coupled to a potential $\epsilon (\xi )$. I restrict myself to shallow perturbations, $\xi (\Omega )={\ell }_0+\zeta (\Omega )$, $|\zeta |\ll {\ell }_0$. A balanced brane implies ${\hat{a}}_0\equiv {\epsilon }^{\prime }({\ell }_0)\sim T/\sigma {\ell }_0$, $T$ is the brane tension, yielding for the velocity of small brane perturbations $c^2\sim T/\sigma \sim {\ell }_0{\hat{a}}_0$. But, ${\hat{a}}_0$ plays the role of the MOND acceleration constant in local gravitational dynamics; so ${\hat{a}}_0\sim c^2/{\ell }_0$. What we, in the brane, perceive as the gravitational potential is $\varphi \equiv \epsilon [\xi (\Omega )]\approx {\varphi }_0+{\hat{a}}_0\zeta$. Aspects of MOND that may emerge naturally as geometrical properties are: a. The special role of acceleration in MOND, and why it is an acceleration, $a_0$, that marks the transition from the standard dynamics much above $a_0$ to scale-invariant dynamics much below $a_0$. b. The intriguing connection of $a_0$ with cosmology. c. The Newtonian limit corresponds to local departure $|\zeta |\ll {\ell }_0$; i.e., $\varphi -{\varphi }_0\sim a_0\zeta \ll a_0{\ell }_0\sim c^2$ - whereas relativity enters when $|\zeta |/\ll {\ell }_0$. The model also opens new vistas for extension, e.g., it points to possible dependence of $a_0$ on $\varphi$, and to $a_0$ losing its status and meaning altogether in the relativistic regime. The required global balance of the brane might solve the `old' cosmological-constant problem. I discuss possible connections with the nearly-de-Sitter nature of our Universe. (Abridged.)

    ↳ gr-qcastro-ph.COastro-ph.GAhep-ph7 citations
42. 42*

    Astrophysical radio background cannot explain the EDGES 21-cm signal: constraints from cooling of non-thermal electrons

    Prateek Sharma🇮🇳

    Recently the EDGES experiment has claimed the detection of an absorption feature centered at 78 MHz. When interpreted as a signature of cosmic dawn, this feature appears at the correct wavelength (corresponding to a redshift range of $z\approx 15-20$) but is larger by at least a factor of two in amplitude compared to the standard 21-cm models. One way to explain the excess radio absorption is by the enhancement of the diffuse radio background at $\nu =1.42$ GHz ($\lambda =21$ cm) in the rest frame of the absorbing neutral hydrogen. Astrophysical scenarios, based on the acceleration of relativistic electrons by accretion on to supermassive black holes (SMBHs) and by supernovae (SN) from first stars, have been proposed to produce the enhanced radio background via synchrotron emission. In this Letter we show that either the synchrotron or the inverse-Compton (IC) cooling time for such electrons is at least three orders of magnitude shorter than the duration of the EDGES signal centered at $z\approx 17$, irrespective of the magnetic field strength. The synchrotron radio emission at 1.42 GHz due to rapidly cooling electrons is $\sim 10^3$ times smaller than the non-cooling estimate. Thus astrophysical scenarios for excess radio background proposed to explain the EDGES signal appear very unlikely.

    ↳ astro-ph.HEhep-phMNRAS(2018)·45 citations
43. 43*

    Dihedral symmetry in $SU(N)$ Yang-Mills theory

    Kyle Aitken🇺🇸 · Aleksey Cherman🇺🇸 · Mithat Ünsal🇺🇸

    We point out that charge conjugation and coordinate reflection symmetries do not commute with the center symmetry of $SU(N)$ YM theory when $N>2$. As a result, for generic values of the $\theta$ angle, the group of discrete zero-form symmetries of YM theory on e.g. the spacetime manifold ${\mathbb{R}}^3\times S^1$ includes the dihedral group $D_{2N}$ which is non-Abelian for $N>2$. At $\theta =\pi$, the non-Abelian factor in the symmetry group is enhanced to $D_{4N}$ due to discrete 't Hooft anomaly considerations. We illustrate these results in YM theory as well as in a simple quantum mechanical model, where we study representation theory as a function of $\theta$ angle.

    ↳ hep-thhep-phPRD(2019)·24 citations
44. 44*

    Gravitational Bose-Einstein condensation in the kinetic regime

    D.G. Levkov🇷🇺 · A.G. Panin🇷🇺 · I.I. Tkachev🇷🇺

    We study Bose-Einstein condensation and formation of Bose stars in the virialized dark matter halos/miniclusters by universal gravitational interactions. We prove that this phenomenon does occur and it is described by kinetic equation. We give expression for the condensation time. Our results suggest that Bose stars may form kinetically in the mainstream dark matter models such as invisible QCD axions and Fuzzy Dark Matter.

    ↳ astro-ph.COastro-ph.GAcond-mat.stat-mechhep-phPRL(2018)·317 citations
45. 45*

    Net-charge fluctuation in Au+Au collisions at energies available at the Facility for Antiproton and Ion Research using the UrQMD model

    Somnath Ghosh🇮🇳 · Provash Mali🇮🇳 · Amitabha Mukhopadhyay🇮🇳

    We have studied the dynamical fluctuation of net-charge of hadrons produced in Au+Au collisions at energies that in near future will be available at the Facility for Antiproton and Ion Research (FAIR). Data simulated by a microscopic transport model based on ultra-relativistic quantum molecular dynamics are analyzed for the purpose. The centrality and pseudorapidity dependence of the net-charge fluctuation of hadrons are examined. Our simulated results are compared with the results available for nucleus-nucleus collision experiments held at similar energies. The gross features of our simulated results on net-charge fluctuations are found to be consistent with the experiment. At incident beam energy $E_{\mathrm{lab}}=10A$ GeV the magnitude of net-charge fluctuation is very large, and in comparison with the rest its centrality dependence appears to be a little unusual. The effect of global charge conservation is expected to be very crucial at FAIR energies. The charge fluctuations measured with varying pesudorapidity window size depend on the collision centrality. The dependence is however exactly opposite in nature to that observed in the Pb+Pb collision at $\sqrt{s_{{}_{NN}}}=2.76$ TeV.

    ↳ nucl-thhep-phPRC(2017)·13 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.