Fri·Dec 22, 2017Friday·December 22, 2017

1. 01*

   The charming beauty of the strong interaction

   Laura Tolos🇩🇪

   Charmed and beauty hadrons in matter are discussed within a unitarized coupled-channel model consistent with heavy-quark spin symmetry. We analyse the formation of D-mesic states as well as the propagation of charmed and beauty hadrons in heavy-ion collisions from LHC to FAIR energies.

   hep-phhep-exnucl-th0 citations
2. 02*

   Strong fields and neutral particle magnetic moment dynamics

   Martin Formanek🇺🇸 · Stefan Evans🇺🇸 · Johann Rafelski🇺🇸 · Andrew Steinmetz🇺🇸 · Cheng-Tao Yang🇺🇸

   Interaction of magnetic moment of point particles with external electromagnetic fields experiences unresolved theoretical and experimental discrepancies. In this work we point out several issues within the relativistic quantum mechanics and the QED and we describe effects related to a new covariant classical model of magnetic moment dynamics. Using this framework we explore the invariant acceleration experienced by neutral particles coupled to an external plane wave field through the magnetic moment: we study the case of ultra relativistic Dirac neutrinos with magnetic moment in the range of $10^{-11}$ to $10^{-20}$ ${\mu }_{\mathrm{B}}$; and we address the case of slowly moving neutrons. We explore how critical accelerations for neutrinos can be experimentally achieved in laser-pulse interactions. The radiation of accelerated neutrinos can serve as an important test distinguishing between Majorana and Dirac nature of neutrinos.

   hep-phphysics.class-phphysics.plasm-phPlasma Phys.Control.Fusion(2018)·15 citations
3. 03*

   Standard Model Effective Field Theory: Integrating out Neutralinos and Charginos in the MSSM

   Huayong Han🇨🇳 · Ran Huo🇺🇸 · Minyuan Jiang🇨🇳 · Jing Shu🇨🇳

   We apply the covariant derivative expansion method to integrate out the neutralinos and charginos in the minimal supersymmetric Standard Model. The results are presented as set of pure bosonic dimension-6 operators in the Standard Model effective field theory. Nontrivial chirality dependence in fermionic covariant derivative expansion are discussed carefully. The results are checked by computing the $h\gamma \gamma$ effective coupling and the electroweak oblique parameters using the Standard Model effective field theory with our effective operators and direct loop calculation. In global fitting the proposed lepton collider constraint projections, special phenomenological emphasis is paid to the gaugino mass unification scenario ($M_2\simeq 2M_1$) and anomaly mediation scenario ($M_1\simeq 3.3M_2$). These results show that the precision measurement experiments in future lepton colliders will provide a very useful complementary job in probing the electroweakino sector, in particular, filling the gap of the soft lepton plus missing $E_T$ channel search left by the traditional collider, where the neutralino as the lightest supersymmetric particle is very degenerated with the next-to-lightest chargino/neutralino.

   hep-phPRD(2018)·8 citations
4. 04*

   Optimising sensitivity to $\gamma$ with $B^0\to D{K}^{+}{\pi }^{-}$, $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ double Dalitz plot analysis

   Daniel Craik🇺🇸 · Timothy Gershon🇬🇧 · Anton Poluektov🇬🇧

   Two of the most powerful methods currently used to determine the angle $\gamma$ of the CKM Unitarity Triangle exploit $B^{+}\to D{K}^{+}$, $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ decays and $B^0\to D{K}^{+}{\pi }^{-}$, $D\to K^{+}{K}^{-}$, ${\pi }^{+}{\pi }^{-}$ decays. It is possible to combine the strengths of both approaches in a "double Dalitz plot" analysis of $B^0\to D{K}^{+}{\pi }^{-}$, $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ decays. The potential sensitivity of such an analysis is investigated in the light of recently published experimental information on the $B^0\to D{K}^{+}{\pi }^{-}$ decay. The formalism is also expanded, compared to previous discussions in the literature, to allow $B^0\to D{K}^{+}{\pi }^{-}$ with any subsequent $D$ decay to be included.

   hep-phhep-exPRD(2018)·20 citations
5. 05*

   Next to leading order QED corrections to the process $\gamma \gamma \to {\mu }^{+}{\mu }^{-}\gamma$

   Mikhail G. Kozlov🇷🇺

   We have calculated one loop quantum electrodynamic corrections to the process $\gamma \gamma \to {\mu }^{+}{\mu }^{-}\gamma$, where all photons are on mass shell and the muon mass is taken into account. The result is obtained in the analytical form and is implemented as functions in the C programming language, which can be used to calculate the cross-section, the differential cross section, and to construct generators. We also present numerical results for corrections to the cross section and to the differential cross section.

   hep-ph1 citation
6. 06*

   Rare FCNC radiative leptonic $B_{s,d}\to \gamma l^{+}{l}^{-}$ decays in the Standard Model

   Anastasiia Kozachuk🇷🇺 · Dmitri Melikhov🇦🇹 · Nikolai Nikitin🇷🇺

   We revisit rare radiative leptonic decays $B_{s,d}\to \gamma e^{+}{e}^{-}$ and $B_{s,d}\to \gamma {\mu }^{+}{\mu }^{-}$ in the Standard Model and provide the updated estimates for various differential distributions (the branching ratios, the forward-backward asymmetry, and $R_{\mu /e}$, the ratio of the differential distribution for muons over electrons in the final state). The new ingredients of this work compared to the existing theoretical analyses are the following: (i) we calculate all $B_d\to \gamma$ and $B_s\to \gamma$ form factors induced by the vector, axial-vector, tensor and pseudotensor quark currents within the relativistic dispersion approach based on the constituent quark picture; (ii) we perform a detailed analysis of the charm-loop contributions to radiative leptonic decays: we obtain constraints imposed by the electromagnetic gauge invariance and discuss the existing ambiguities in the charmonia contributions.

   hep-phPRD(2018)·57 citations
7. 07*

   Prompt inclusive production of $J/\psi$, ${\psi }^{\prime }$ and ${\chi }_c$ mesons at the LHC in forward directions within the NRQCD $k_t$-factorization approach - search for the onset of gluon saturation

   Anna Cisek🇵🇱 · Antoni Szczurek🇵🇱

   We discuss prompt production of $J/\psi$ mesons in proton-proton collisions at the LHC within NRQCD $k_t$-factorization approach using Kimber-Martin-Ryskin (KMR) unintegrated gluon distributions (UGDF). We include both direct color-singlet production ($gg\to J/\psi g$) as well as a feed-down from ${\chi }_c\to J/\psi \gamma$ and ${\psi }^{\prime }\to J/\psi X$ decays. The production of the decaying mesons (${\chi }_c$ or ${\psi }^{\prime }$) is also calculated within NRQCD $k_t$-factorization approach. The corresponding matrix elements for $gg\to J/\psi$ g, $gg\to {\psi }^{\prime }g$ and $gg\to {\chi }_c$ include parameters of the nonrelativistic space wave functions of the quarkonia at $r=0$, which are taken from potential models in the literature. We get the ratio of the corresponding cross section ratio for ${\chi }_c(2)$-to-${\chi }_c(1)$ at midrapidities much closer to experimental data than obtained in a recent analysis. Differential distributions in rapidity and transverse momentum of $J/\psi$ and ${\psi }^{\prime }$ are calculated and compared with experimental data of the ALICE and LHCb collaborations. We discuss a possible onset of gluon saturation effects in the production of $J/\psi$ and ${\chi }_c$ mesons at forward/backward rapidities. We show that it is neccessary to modify the standard KMR UGDF to describe ALICE and LHCb data. A mixed UGDF scenario was proposed. Then we can describe the experimental data for $J/\psi$ production within model uncertainties with color-singlet component only. Therefore our theoretical results leave only a relatively small room for the color-octet contributions.

   hep-phPRD(2018)·23 citations
8. 08*

   Power corrections to the HTL effective Lagrangian of QED

   Stefano Carignano🇮🇹 · Cristina Manuel🇪🇸 · Joan Soto🇪🇸

   We present compact expressions for the power corrections to the hard thermal loop (HTL) Lagrangian of QED in $d$ space dimensions. These are corrections of order $(L/T{)}^2$, valid for momenta $L\ll T$, where $T$ is the temperature. In the limit $d\to 3$ we achieve a consistent regularization of both infrared and ultraviolet divergences, which respects the gauge symmetry of the theory. Dimensional regularization also allows us to witness subtle cancellations of infrared divergences. We also discuss how to generalise our results in the presence of a chemical potential, so as to obtain the power corrections to the hard dense loop (HDL) Lagrangian.

   hep-phPLB(2018)·36 citations
9. 09*

   Towards a new paradigm for heavy-light meson spectroscopy

   Meng-Lin Du🇩🇪 · Miguel Albaladejo🇪🇸 · Pedro Fernandez-Soler🇪🇸 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Ulf-G. Meißner🇩🇪 · Juan Nieves🇪🇸 · De-Liang Yao🇪🇸

   Since 2003 many new hadrons, including the lowest-lying positive-parity charm-strange mesons $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$, were observed that do not conform with quark model expectations. It was recently demonstrated that various puzzles in the charm meson spectrum find a natural resolution, if the SU(3) multiplets for the lightest scalar and axial-vector states, amongst them the $D_{s0}^{\ast }(2317)$ and the $D_{s1}(2460)$, owe their existence to the nonperturbative dynamics of Goldstone-Boson scattering off $D_{(s)}$ and $D_{(s)}^{\ast }$ mesons. Most importantly the ordering of the lightest strange and nonstrange scalars becomes natural. In this work we demonstrate for the first time that this mechanism is strongly supported by the recent high quality data on the $B^{-}\to D^{+}{\pi }^{-}{\pi }^{-}$ provided by the LHCb experiment. This implies that the lowest quark-model positive-parity charm mesons, together with their bottom counterparts, if realized in nature, do not form the ground-state multiplet. This is similar to the pattern that has been established for the scalar mesons made from light up, down and strange quarks, where the lowest multiplet is considered to be made of states not described by the quark model. In a broader view, the hadron spectrum must be viewed as more than a collection of quark model states.

   hep-phhep-exhep-latnucl-thPRD(2018)·118 citations
10. 10*

    Mass sensitivity of the three-flavor chiral phase transition

    Simon Resch🇩🇪 · Fabian Rennecke🇺🇸 · Bernd-Jochen Schaefer🇩🇪

    The mass sensitivity of the chiral phase transition of QCD with and without axial $U_A(1)$-symmetry breaking at vanishing and finite quark chemical potential is investigated. To focus on the low-energy sector of QCD, a quark-meson model with three dynamical quark flavors is employed. Non-perturbative quantum fluctuations are taken into account with the functional renormalization group. The inherent ambiguities in fixing the low-energy model parameters away from the physical mass point and their consequences for spontaneous chiral symmetry breaking are discussed in detail and a heuristic parameter fixing scheme motivated by chiral perturbation theory is proposed. The influence of vacuum and thermal fluctuations of quarks and mesons on the order of the chiral phase transition is additionally assessed with a mean-field analysis.

    hep-phhep-thnucl-thPRD(2019)·65 citations
11. 11*

    Compatibility of a dark matter discovery at XENONnT/LZ with the WIMP thermal production mechanism

    Riccardo Catena🇸🇪 · Jan Conrad🇸🇪 · Martin B. Krauss🇸🇪

    The discovery of dark matter (DM) at XENONnT or LZ would place constraints on DM particle mass and coupling constants. It is interesting to ask when these constraints can be compatible with the DM thermal production mechanism. We address this question within the most general set of renormalisable models that preserve Lorentz and gauge symmetry, and that extend the Standard Model by one DM candidate of mass $m_{\mathrm{DM}}$ and one particle of mass $M_{med}$ mediating DM-quark interactions. Our analysis divides into two parts. First, we postulate that XENONnT/LZ has detected ${\mu }_S\sim \mathcal{O}(100)$ signal events, and use this input to calculate the DM relic density, ${\Omega }_{DM}{h}^2$. Then, we identify the regions in the $M_{med}-{\Omega }_{DM}{h}^2$ plane which are compatible with the observed signal and with current CMB data. We find that for most of the models considered here, $\mathcal{O}(100)$ signal events at XENONnT/LZ and the DM thermal production are only compatible for resonant DM annihilations, i.e. for $M_{med}\simeq 2m_{DM}$. In this case, XENONnT/LZ would be able to simultaneously measure $m_{DM}$ and $M_{med}$. We also discuss the dependence of our results on $m_{DM}$, ${\mu }_S$ and the DM spin, and provide analytic expressions for annihilation cross-sections and mediator decay widths for all models considered in this study.

    hep-phastro-ph.COPRD(2018)·16 citations
12. 12*

    An automated subtraction of NLO EW infrared divergences

    Marek Schönherr🇨🇭

    In this paper a complete generalisation of the Catani-Seymour dipole subtraction method to next-to-leading order electroweak calculations is presented. All singularities due to photon and gluon radiation off both massless and massive partons in the presence of both massless and massive spectators are accounted for. Particular attention is paid to the simultaneous subtraction of singularities of both QCD and electroweak origin which are present in the next-to-leading order corrections to processes with more than one perturbative order contributing at Born level. Similarly, embedding non-dipole-like photon splittings in the dipole subtraction scheme discussed. The implementation of the formulated subtraction scheme in the framework of the Sherpa Monte-Carlo event generator is detailed and numerous internal consistency checks validating the obtained results are presented.

    hep-phEPJC(2018)·89 citations
13. 13*

    Dynamically generated hadronic states in the $\bar{K}N$ and $\eta N$ coupled-channels interactions

    Ales Cieply🇨🇿

    We compare and review the theoretical predictions for the $\bar{K}N$ and $\eta N$ elastic amplitudes where sizable variations are found among the considered approaches, especially at subthreshold energies relevant for studies of kaonic atoms and meson-nuclear quasi-bound states. Conditions for an appearance of dynamically generated states in meson-baryon multi-channel interactions are established and discussed for the $\bar{K}N$ and $\eta N$ systems.

    hep-phnucl-thEPJ Web Conf.(2018)·0 citations
14. 14*

    A New Light Higgs Boson and Short-Baseline Neutrino Anomalies

    J. Asaadi🇺🇸 · E. Church🇺🇸 · R. Guenette🇺🇸 · B. J. P. Jones🇺🇸 · A. M. Szelc🇬🇧

    The low-energy excesses observed by the MiniBooNE experiment have, to date, defied a convinc- ing explanation under the standard model even with accommodation for non-zero neutrino mass. In this paper we explore a new oscillation mechanism to explain these anomalies, invoking a light neu- trinophilic Higgs boson, conceived to induce a low Dirac neutrino mass in accord with experimental limits. Beam neutrinos forward-scattering off of a locally over-dense relic neutrino background give rise to a novel matter-effect with an energy-specific resonance. An enhanced oscillation around this resonance peak produces flavor transitions which are highly consistent with the MiniBooNE neutrino- and antineutrino-mode data sets. The model provides substantially improved ${\chi }^2$ values beyond either the no-oscillation hypothesis or the more commonly explored 3+1 sterile neutrino hy- pothesis. This mechanism would introduce distinctive signatures at each baseline in the upcoming SBN program at Fermilab, presenting opportunities for further exploration.

    hep-phhep-exPRD(2018)·48 citations
15. 15*

    Solving the fermionic mass hierarchy of the standard model

    Gauhar Abbas🇮🇳

    We show that a simultaneous explanation for fermionic mass hierarchy among and within the fermionic families, quark-mixing, can be obtained in an extension of the standard model, with real singlet scalar fields, which is UV completed by vector-like fermions and a strongly interacting sector.

    hep-phInt.J.Mod.Phys.A(2019)·24 citations
16. 16*

    Dark Matter from Electroweak Single Top Production

    Tilman Plehn🇩🇪 · Jennifer Thompson🇩🇪 · Susanne Westhoff🇩🇪

    Dark matter scenarios with spin-0 mediators in the $s$-channel have be tested in well-established processes with missing energy, such as top-pair- and mono-jet-associated production. We suggest electroweak single top production in association with a dark matter pair as an alternative channel. Based on a realistic analysis for the LHC at 13 TeV, we demonstrate how to efficiently discriminate between the signal and Standard-Model background using event kinematics. With $300{\text{fb}}^{-1}(3{\text{ab}}^{-1})$ of data luminosity, on-shell scalar mediators with a coupling strength $g_S^t=1$ to top quarks can be probed up to masses of $180(360)\text{GeV}$. Single-top-associated dark matter production should thus be included as an independent search channel in the LHC dark matter program.

    hep-phhep-exPRD(2018)·16 citations
17. 17*

    Resummation of Goldstone Infrared Divergences: A Proof to All Orders

    Jose R. Espinosa🇪🇸 · Thomas Konstandin🇩🇪

    The perturbative effective potential calculated in Landau gauge suffers from infrared problems due to Goldstone boson loops. These divergences are spurious and can be removed by a resummation procedure that amounts to a shift of the mass of soft Goldstones. We prove this to all loops using an effective theory approach, providing a compact recipe for the shift of the Goldstone mass that relies on the use of the method of regions to split soft and hard Goldstone contributions.

    hep-phhep-thPRD(2018)·18 citations
18. 18*

    Polarized double-virtual amplitudes for heavy-quark pair production

    L. Chen🇩🇪 · M. Czakon🇩🇪 · R. Poncelet🇩🇪

    We present the two-loop virtual amplitudes for heavy-quark pair production in light quark-antiquark annihilation and gluon fusion channels, including full spin and color dependence. We use expansions around kinematical limits and numerical integration to obtain results for the involved master integrals. From these, we determine the renormalised infrared finite remainders of the coefficients of amplitude decompositions in terms of color and spin structures. The remainders are given in form of numerical interpolation grids supported by expansions around the production threshold and the high energy limit. Finally, we provide the spin density matrix, which encodes the heavy-quark spin correlations and is sufficient for phenomenological applications. Our results are necessary for the derivation of top-quark pair production cross sections in hadron collisions in the narrow width approximation with next-to-next-to-leading order accuracy in QCD.

    hep-phJHEP(2018)·30 citations
19. 19*

    Effective-particle approach to bound states of quarks and gluons in QCD

    María Gómez-Rocha🇮🇹 · Kamil Serafin🇵🇱

    A general approach to the construction of bound states in quantum field theory, called the renormalization group procedure for effective particles (RGPEP), was applied recently to single heavy-flavor QCD in order to study its utility beyond illustration of its general features. This heavy-flavor QCD is chosen as the simplest available context in which the dynamics of quark and gluon bound states can be studied with the required rigor using Minkowski-space Hamiltonian operators in the Fock space, taking the advantage of asymptotic freedom. The effective quarks and gluons differ from the point-like canonical ones by having a finite size $s$. Their size plays the role of renormalization group parameter. However, instead of integrating out high-energy degrees of freedom, our RGPEP procedure is based on a transformation of the front-form QCD Hamiltonian from its canonical form with counterterms to the renormalized, scale-dependent operator that acts in the Fock space of effective quanta of quark and gluon fields, keeping all degrees of freedom intact but accounting for them in a transformed form. We discuss different behavior of effective particles interacting at different energy scales, corresponding to different size s. Namely, we cover phenomena ranging from asymptotic freedom at highest energies down to the scales at which the formation of bound states occurs. We briefly present recent applications of the RGPEP to quarks and gluons in QCD, which have been developed using expansion in powers of the Fock-space Hamiltonian running coupling. After observing that the QCD effective Hamiltonian satisfies the requirement of producing asymptotic freedom, we derive the leading effective interaction between quarks in heavy-flavor QCD. An effective confining effect is derived as a result of assuming that the non-Abelian and non-perturbative dynamics causes effective gluons to have mass.

    hep-phPoS(2018)·0 citations
20. 20*

    Single inclusive jet production and the nuclear modification ratio at very forward rapidity in proton-lead collisions with $\sqrt{s_{NN}}$ = 5.02 TeV

    Marcin Bury🇵🇱 · Hans Van Haevermaet🇧🇪 · Andreas Van Hameren🇵🇱 · Pierre Van Mechelen🇧🇪 · Krzysztof Kutak🇵🇱 · Mirko Serino🇵🇱

    We present calculations of single inclusive jet transverse momentum and energy spectra at forward rapidity ($5.2<y<6.6$) in proton-lead collisions with $\sqrt{s_{NN}}$ = 5.02 TeV. The predictions are obtained with the KaTie Monte Carlo event generator, which allows to calculate interactions within the High Energy Factorisation framework. The tree-level matrix element results are subsequently interfaced with the CASCADE Monte Carlo event generator to account for hadronisation. The effects of the saturation of the gluon density, leading to suppression of the cross section, are investigated.

    hep-phPLB(2018)·15 citations
21. 21*

    Connections between collinear and transverse-momentum-dependent polarized observables within the Collins-Soper-Sterman formalism

    Leonard Gamberg🇺🇸 · Andreas Metz🇺🇸 · Daniel Pitonyak🇺🇸 · Alexei Prokudin🇺🇸

    We extend the improved Collins-Soper-Sterman (iCSS) $W+Y$ construction recently presented in~\cite{Collins:2016hqq} to the case of polarized observables, where we focus in particular on the Sivers effect in semi-inclusive deep-inelastic scattering. We further show how one recovers the expected leading-order collinear twist-3 result from a (weighted) $q_T$-integral of the differential cross section. We are also able to demonstrate the validity of the well-known relation between the (TMD) Sivers function and the (collinear twist-3) Qiu-Sterman function within the iCSS framework. This relation allows for their interpretation as functions yielding the average transverse momentum of unpolarized quarks in a transversely polarized spin-$\frac{1}{2}$ target. We further outline how this study can be generalized to other polarized quantities.

    hep-phhep-exPLB(2018)·23 citations
22. 22*

    Single-top production and rare top interactions

    Pratishruti Saha🇮🇳 · Ken Kiers🇺🇸 · Alejandro Szynkman🇦🇷

    The study of the top quark's properties is an important part of the LHC programme. In earlier work, we have studied the rare decay $t\to b\bar{b}c$, using effective operators to capture the effects of physics beyond the Standard Model. However top decay is primarily sensitive to new physics in the sub-TeV energy regime. If this new physics resides at a higher energy scale, then one needs to turn to single-top production. In this paper, we use the $s$-channel and $t$-channel single-top production measurements to constrain the new physics parameter space associated with such contact interactions. We also study the net top polarization as a means to distinguish between contributions from operators involving different fermion chiralities and Lorentz structures.

    hep-phPRD(2018)·0 citations
23. 23*

    Inflation from High-Scale Supersymmetry Breaking

    Valerie Domcke🇩🇪 · Kai Schmitz🇩🇪

    Supersymmetry breaking close to the scale of grand unification can explain cosmic inflation. As we demonstrate in this paper, this can be achieved in strongly coupled supersymmetric gauge theories, such that the energy scales of inflation and supersymmetry breaking are generated dynamically. As a consequence, both scales are related to each other and exponentially suppressed compared to the Planck scale. As an example, we consider a dynamical model in which gauging a global flavor symmetry in the supersymmetry-breaking sector gives rise to a Fayet-Iliopoulos D term. This results in successful D-term hybrid inflation in agreement with all theoretical and phenomenological constraints. The gauged flavor symmetry can be identified with U(1)_B-L, where B and L denote baryon and lepton number, respectively. In the end, we arrive at a consistent cosmological scenario that provides a unified picture of high-scale supersymmetry breaking, viable D-term hybrid inflation, spontaneous B-L breaking at the scale of grand unification, baryogenesis via leptogenesis, and standard model neutrino masses due to the type-I seesaw mechanism.

    hep-phastro-ph.COhep-thPRD(2018)·35 citations
24. 24*

    Flavour issues in warped custodial models: $B$ anomalies and rare $K$ decays

    Giancarlo D'Ambrosio🇮🇹 · Abhishek M. Iyer🇮🇹

    We explore the flavour structure of custodial Randall-Sundrum (RS) models in the context of the recently observed deviations in the decay of the $B$ mesons. The anomalies in the $b\to sll$ processes can be easily fit with partially composite second generation leptons and third generation quarks. We establish correlation with the parameter space consistent with the flavour anomalies in the neutral current sector and obtain predictions for rare $K$- decay which are likely to be another candle for NP with increased precision. Two scenarios are considered: A) Right handed muon coupled more to NP that the corresponding muon doublets (unorthodox case). Non-universality exists in the right handed sector. B) Standard scenario with anomalies explained primarily by non-universal couplings to the lepton doublets. The prediction for rare $K$-decays are different according to the scenario, thereby serving as a useful discriminatory tool. We note that, in this setup $R(D^{\ast })$ is at best consistent with the SM and increasing the compositeness of the ${\tau }_L$ generates a net contribution becoming below the SM expectation. This makes this framework fairly predictive and easily verifiable. Finally, we also comment on the implications of flavour violation in the lepton sector and present an explicit example with the implementation of bulk leptonic MFV which helps in alleviating the constraints.

    hep-phEPJC(2018)·29 citations
25. 25*

    A C++ interface to QCDNUM

    Valerio Bertone🇳🇱 · Michiel Botje🇳🇱

    In this document we report on the recent development of a C++ interface to the FORTRAN-based evolution program QCDNUM. A short description of the interface is given with a few basic examples of its usage.

    hep-phcs.MS3 citations
26. 26*

    Generalisation of the identity method for determination of high-order moments of multiplicity distributions with a software implementation

    Maja Mackowiak-Pawlowska🇵🇱 · Piotr Przybyla🇬🇧

    The incomplete particle identification limits the experimentally-available phase space region for identified particle analysis. This problem affects ongoing fluctuation and correlation studies including the search for the critical point of strongly interacting matter performed on SPS and RHIC accelerators. In this paper we provide a procedure to obtain $n$-th order moments of the multiplicity distribution using the identity method, generalising previously published solutions for $n=2$ and $n=3$. Moreover, we present an open source software implementation of this computation, called \textit{Idhim}, that allows one to obtain the true moments of identified particle multiplicity distributions from the measured ones provided the response function of the detector is known.

    ↳ hep-exhep-phnucl-exEPJC(2018)·3 citations
27. 27*

    Symmetry Realization via a Dynamical Inverse Higgs Mechanism

    Ira Z. Rothstein🇺🇸 · Prashant Shrivastava🇺🇸

    The Ward identities associated with spontaneously broken symmetries can be saturated by Goldstone bosons. However, when space-time symmetries are broken, the number of Goldstone bosons necessary to non-linearly realize the symmetry can be less than the number of broken generators. The loss of Goldstones may be due to a redundancy or the generation of a gap. This phenomena is called an Inverse Higgs Mechanism (IHM). However, there are cases when a Goldstone boson associated with a broken generator does not appear in the low energy theory despite the lack of the existence of an associated IHM. In this paper we will show that in such cases the relevant broken symmetry can be realized, without the aid of an associated Goldstone, if there exists a proper set of operator constraints, which we call a Dynamical Inverse Higgs Mechanism (DIHM). We consider the spontaneous breaking of boosts, rotations and conformal transformations in the context of Fermi liquids, finding three possible paths to symmetry realization: pure Goldstones, no Goldstones and DIHM, or some mixture thereof. We show that in the two dimensional degenerate electron system the DIHM route is the only consistent way to realize spontaneously broken boosts and dilatations, while in three dimensions these symmetries could just as well be realized via the inclusion of non-derivatively coupled Goldstone bosons. We have present the action, including the leading order non-linearities, for the rotational Goldstone (angulon), and discuss the constraint associated with the possible DIHM that would need to be imposed to remove it from the spectrum. Finally we discuss the conditions under which Goldstone bosons are non-derivatively coupled, a necessary condition for the existence of a Dynamical Inverse Higgs Constraint (DIHC), generalizaing the results for Vishwanath and Wantanabe.

    ↳ hep-thcond-mat.str-elhep-phnucl-thJHEP(2018)·27 citations
28. 28*

    Symmetry Obstruction to Fermi Liquid Behavior in the Unitary Limit

    Ira Z. Rothstein🇺🇸 · Prashant Shrivastava🇺🇸

    We show that a Fermi gas, in three dimensions, at temperatures above the superconducting phase transition but below the Fermi temperature, can not be described by Fermi Liquid Theory (FLT) in the unitary limit where the scattering length diverges. The result follows by showing that the there are no effective field theory descriptions that both behave like a Fermi liquid and properly non-linearly realize the spontaneously broken boost and conformal invariance of the system.

    ↳ cond-mat.str-elhep-phhep-thnucl-thPRB(2019)·23 citations
29. 29*

    Evidence of a truncated spectrum in the angular correlation function of the cosmic microwave background

    Fulvio Melia🇺🇸 · Martin Lopez-Corredoira🇪🇸

    The lack of large-angle correlations in the fluctuations of the cosmic microwave background (CMB) conflicts with predictions of slow-roll inflation. But though probabilities (< 0.24%) for the missing correlations disfavor the conventional picture at > 3 sigma, factors not associated with the model itself may be contributing to the tension. Here we aim to show that the absence of large-angle correlations is best explained with the introduction of a non-zero minimum wavenumber k_min for the fluctuation power spectrum P(k). We assume that quantum fluctuations were generated in the early Universe with a well-defined power spectrum P(k), though with a cutoff k_min not equal to 0. We then re-calculate the angular correlation function of the CMB and compare it with Planck observations. The Planck 2013 data rule out a zero k_min at a confidence level exceeding 8 sigma. Whereas purely slow-roll inflation would have stretched all fluctuations beyond the horizon, producing a P(k) with k_min=0---and therefore strong correlations at all angles---a k_min > 0 would signal the presence of a maximum wavelength at the time (t_dec) of decoupling. This argues against the basic inflationary paradigm---perhaps even suggesting non-inflationary alternatives---for the origin and growth of perturbations in the early Universe. In at least one competing cosmology, the R_h=ct universe, the inferred k_min corresponds to the gravitational radius at t_dec.

    ↳ astro-ph.COgr-qchep-phhep-thAstron.Astrophys.(2018)·36 citations
30. 30*

    The gluon condensation effects in the DAMPE cosmic ray spectrum of electrons and positrons

    Wei Zhu Jiangshan Lan Jianhong Ruan · Fan Wang

    Gluons dominate the proton behavior at high energy collisions, they can be condensed at ultra high energy. The collisions of the accelerated high energy protons with interplanetary matter in cosmic rays will produce a huge number of secondary particles at the gluon condensate energy region, which break the primary power-law of cosmic rays. The above predictions seem to be consistent with the recent DAMPE data concerning the electron plus positron spectra. We find that the smoothly broken power-law at $\sim 0.9TeV$ and $3\sim 4TeV$ in the DAMPE data can be understood as the gluon condensation effects in proton.

    ↳ astro-ph.HEhep-exhep-ph1 citation
31. 31*

    Noether symmetry in a nonlocal f(T) Gravity

    Phongpichit Channuie (Walailak U.)🇹🇭 · Davood Momeni (Sultan Qaboos U.)🇴🇲

    It is well known that the Noether symmetry approach proves to be very useful not only to fix physically viable cosmological models but also to reduce dynamics and achieve exact solutions. In this work, We examine a formal framework of nonlocal $f(T)$ theory of gravity through the Noether symmetry approach. The Noether equations of the nonlocal $f(T)$ theory are obtained for flat FLRW universe. We analyse the dynamics of the field in a nonlocal $f(T)$ gravity admitted by the Noether symmetry. We observe that there exists a transition from a deceleration phase to the acceleration one in our present analysis. We check statefinder parameters for the obtained solutions which imply that some particular solutions are comparable with the Lambda-CDM model.

    ↳ gr-qchep-phhep-thNPB(2018)·20 citations
32. 32*

    Horizon Feedback Inflation

    Malcolm Fairbairn🇬🇧 · Tommi Markkanen🇬🇧 · David Rodriguez-Roman🇬🇧

    We consider the effect of the Gibbons-Hawking radiation on the inflaton in the situation where it is coupled to a large number of spectator fields. We argue that this will lead to two important effects - a thermal contribution to the potential and a gradual change in parameters in the Lagrangian which results from thermodynamic and energy conservation arguments. We present a scenario of hilltop inflation where the field starts trapped at the origin before slowly experiencing a phase transition during which the field extremely slowly moves towards its zero temperature expectation value. We show that it is possible to obtain enough e-folds of expansion as well as the correct spectrum of perturbations without hugely fine-tuned parameters in the potential (albeit with many spectator fields). We also comment on how initial conditions for inflation can arise naturally in this situation.

    ↳ gr-qcastro-ph.COhep-phEPJC(2018)·11 citations
33. 33*

    D mesons in strongly magnetized asymmetric nuclear matter

    P. Sushruth Reddy🇮🇳 · C. S. Amal Jahan🇮🇳 · Nikhil Dhale🇮🇳 · Amruta Mishra🇮🇳 · Juergen Schaffner-Bielich🇩🇪

    The medium modifications of the open charm mesons ($D$ and $\bar{D}$) are studied in isospin asymmetric nuclear matter in the presence of strong magnetic fields, using a chiral effective model. The mass modifications of these mesons in the effective hadronic model, arise due to their interactions with the protons, neutrons and the scalar mesons (non-strange isoscalar $\sigma$, strange isoscalar, $\zeta$ and non-strange isovector, $\delta$), in the magnetized nuclear matter. In the presence of magnetic field, for the charged baryon, i.e., the proton, the number density as well as the scalar density have contributions due to the summation over the Landau energy levels. For a given value of the baryon density, ${\rho }_B$, and isospin asymmetry, the scalar fields are solved self consistently from their coupled equations of motion. The modifications of the masses of the $D$ and $\bar{D}$ mesons are calculated, from the medium modifications of the scalar fields and the nucleons. The effects of the anomalous magnetic moments of the nucleons on the masses of the open charm mesons are also investigated in the present work. The effects of isospin asymmetry as well as of the anomalous magnetic moments are observed to be prominent at high densities for large values of magnetic fields.

    ↳ nucl-thhep-phPRC(2018)·54 citations
34. 34*

    Effective theory of the D = 3 center vortex ensemble

    L. E. Oxman🇧🇷 · H. Reinhardt🇩🇪

    By means of lattice calculations, center vortices have been established as the infrared dominant gauge field configurations of Yang-Mills theory. In this work, we investigate an ensemble of center vortices in D = 3 Euclidean space-time dimension where they form closed flux loops. To account for the properties of center vortices detected on the lattice, they are equipped with tension, stiffness and a repulsive contact interaction. The ensemble of oriented center vortices is then mapped onto an effective theory of a complex scalar field with a U(1) symmetry. For a positive tension, small vortex loops are favoured and the Wilson loop displays a perimeter law while for a negative tension, large loops dominate the ensemble. In this case the U(1) symmetry of the effective scalar field theory is spontaneously broken and the Wilson loop shows an area law. To account for the large quantum fluctuations of the corresponding Goldstone modes, we use a lattice representation, which results in an XY model with frustration, for which we also study the Villain approximation.

    ↳ hep-thhep-phEPJC(2018)·10 citations
35. 35*

    Searching for Light Relics with Large-Scale Structure

    Daniel Baumann🇳🇱 · Daniel Green🇺🇸 · Benjamin Wallisch🇬🇧

    Light thermal relics of the hot big bang, often quantified by the parameter $N_{\mathrm{eff}}$, are one of the primary targets of cosmological measurements. At present, the energy density in such relics is constrained to be less than ten percent of the total energy density in radiation. Upcoming cosmic microwave background (CMB) experiments, however, have the potential to measure the radiation density at the one-percent level, which is close to well-motivated theoretical targets. In this paper, we explore to what degree the CMB observations can be enhanced by future large-scale structure surveys. We carefully isolate the information encoded in the shape of the galaxy power spectrum and in the spectrum of baryon acoustic oscillations (BAO). We find that measurements of the shape of the power spectrum can significantly improve on current and near-term CMB experiments. We also show that the phase shift of the BAO spectrum induced by relic neutrinos can be detected at high significance in future experiments.

    ↳ astro-ph.COhep-phhep-thJCAP(2018)·135 citations
36. 36*

    Testing Noncommutative Spacetimes and Violations of the Pauli Exclusion Principle with underground experiments

    Andrea Addazi🇨🇳 · Pierluigi Belli🇮🇹 · Rita Bernabei🇮🇹 · Antonino Marciano🇨🇳

    We propose to deploy limits that arise from different tests of the Pauli Exclusion Principle in order: i) to provide theories of quantum gravity with an experimental guidance; ii) to distinguish among the plethora of possible models the ones that are already ruled out by current data; iii) to direct future attempts to be in accordance with experimental constraints. We firstly review experimental bounds on nuclear processes forbidden by the Pauli Exclusion Principle, which have been derived by several experimental collaborations making use of different detector materials. Distinct features of the experimental devices entail sensitivities on the constraints hitherto achieved that may differ one another by several orders of magnitude. We show that with choices of these limits, renown examples of flat noncommutative space-time instantiations of quantum gravity can be heavily constrained, and eventually ruled out. We devote particular attention to the analysis of the $\kappa$-Minkowski and $\theta$-Minkowski noncommutative spacetimes. These are deeply connected to some scenarios in string theory, loop quantum gravity and noncommutative geometry. We emphasize that the severe constraints on these quantum spacetimes, although cannot rule out theories of top-down quantum gravity to whom are connected in various way, provide a powerful limitations of those models that it will make sense to focus on in the future.

    ↳ hep-thgr-qchep-phCPC(2018)·30 citations
37. 37*

    The Palatini side of inflationary attractors

    Laur Järv🇪🇪 · Antonio Racioppi🇪🇪 · Tommi Tenkanen🇬🇧

    We perform an analysis of models of chaotic inflation where the inflaton field $\varphi$ is coupled non-minimally to gravity via $\xi {\varphi }^n{g}^{\mu \nu }{R}_{\mu \nu }(\Gamma ),n>0$. We focus on the Palatini theory of gravity, i.e. the case where the assumptions of the General Relativity are relaxed (that of the connection being the Levi-Civita one) and the gravitational degrees of freedom are encoded not only in the metric but also the connection $\Gamma$, which is treated as an independent variable. We show that in this case the famous attractor behaviour of simple non-minimally coupled models of inflation is lost. Therefore the attractors are not universal but their existence depends on the underlying theory of gravity in a subtle way. We discuss what this means for chaotic models and their observational consequences.

    ↳ gr-qchep-phPRD(2018)·108 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.