Tue·Sep 24, 2019Tuesday·September 24, 2019

1. 01*

   On the ATLAS Top Mass Measurements and the Potential for Stealth Stop Contamination

   Timothy Cohen🇺🇸 · Stephanie Majewski🇺🇸 · Bryan Ostdiek🇺🇸 · Peter Zheng🇺🇸

   The discovery of the stop - the Supersymmetric partner of the top quark - is a key goal of the physics program enabled by the Large Hadron Collider. Although much of the accessible parameter space has already been probed, all current searches assume the top mass is known. This is relevant for the "stealth stop" regime, which is characterized by decay kinematics that force the final state top quark off its mass shell; such decays would contaminate the top mass measurements. We investigate the resulting bias imparted to the template method based ATLAS approach. A careful recasting of these results shows that effect can be as large as 2.0 GeV, comparable to the current quoted uncertainty on the top mass. Thus, a robust exploration of the stealth stop splinter requires the simultaneous consideration of the impact on the top mass. Additionally, we explore the robustness of the template technique, and point out a simple strategy for improving the methodology implemented for the semi-leptonic channel.

   hep-phhep-exJHEP(2020)·9 citations
2. 02*

   Gravitational footprints of massive neutrinos and lepton number breaking

   Andrea Addazi🇨🇳 · Antonino Marcianò🇨🇳 · António P. Morais🇵🇹 · Roman Pasechnik🇸🇪 · Rahul Srivastava🇪🇸 · José W. F. Valle🇪🇸

   We investigate the production of primordial Gravitational Waves (GWs) arising from First Order Phase Transitions (FOPTs) associated to neutrino mass generation in the context of type-I and inverse seesaw schemes. We examine both "high-scale" as well as "low-scale" variants, with either explicit or spontaneously broken lepton number symmetry $U(1{)}_L$ in the neutrino sector. In the latter case, a pseudo-Goldstone majoron-like boson may provide a candidate for cosmological dark matter. We find that schemes with softly-broken $U(1{)}_L$ and with single Higgs-doublet scalar sector lead to either no FOPTs or too weak FOPTs, precluding the detectability of GWs in present or near future measurements. Nevertheless, we found that, in the majoron-like seesaw scheme with spontaneously broken $U(1{)}_L$ at finite temperatures, one can have strong FOPTs and non-trivial primordial GW spectra which can fall well within the frequency and amplitude sensitivity of upcoming experiments, including LISA, BBO and u-DECIGO. However, GWs observability clashes with invisible Higgs decay constraints from the LHC. A simple and consistent fix is to assume the majoron-like mass to lie above the Higgs-decay kinematical threshold. We also found that the majoron-like variant of the low-scale seesaw mechanism implies a different GW spectrum than the one expected in the high-scale seesaw. This feature will be testable in future experiments. Our analysis shows that GWs can provide a new and complementary portal to test the neutrino mass generation mechanism.

   hep-phastro-ph.COgr-qchep-ex+1PLB(2020)·33 citations
3. 03*

   Dual Meissner Effect and Quark Confinement Potential in S U(3) Dual QCD Formalism

   Garima Punetha🇮🇳 · H.C. Chandola🇮🇳

   The mechanism of color confinement has been studied in the framework of SU (3) color gauge theory in terms of abelian fields and monopoles extracted by adopting magnetic symmetry. The existence of the mechanism of color confinement corresponds to the dual Meissner effect caused by monopoles. The two length scales, i.e. the penetration depth and coherence length are defined to demonstrate the scaling nature of the QCD vacuum and their ratio defines the Ginzburg-Landau parameter indicating the border of type I and type II dual superconductor. The existence of these two length scales describes the intrinsic shape of the confining flux-tube and is a characteristic of the dual superconductor model of confinement in QCD. As a result, the quark confining potential has been computed and the resulting expression of string tension has been constructed in the infrared sector of SU (3) Dual QCD formulation. Moreover, with the introduction of dynamical quarks the flux tube breaks and leads to the creation of quark anti-quark pairs. Finite temperature quark confining potential and the associated string tension has also been extracted which demonstrates a considerable reduction in the vicinity of critical temperature showing agreement with the recent lattice studies.

   hep-phActa Phys.Polon.B(2019)·2 citations
4. 04*

   Probing Gluon Sivers Function in Inelastic Photoproduction of $J/\psi$ at the EIC

   Raj Kishore🇮🇳 · Asmita Mukherjee🇮🇳 · Sangem Rajesh🇮🇹

   We present a recent calculation of the single spin asymmetry in inclusive photoproducton of $J/\psi$ at the future EIC, that can be used to probe the gluon Sivers function.

   hep-ph0 citations
5. 05*

   Gluon mass scale through nonlinearities and vertex interplay

   A. C. Aguilar🇧🇷 · M. N. Ferreira🇧🇷 · C. T. Figueiredo🇧🇷 · J. Papavassiliou🇪🇸

   We present a novel analysis of the gluon gap equation, where its full nonlinear structure is duly taken into account. In particular, while in previous treatments the linearization of this homogeneous integral equation introduced an indeterminacy in the scale of the corresponding mass, the current approach determines it uniquely, once the value of the gauge coupling at a given renormalization point is used as input. A crucial ingredient for this construction is the "kinetic term" of the gluon propagator, whose form is not obtained from the complicated equation governing its evolution, but is rather approximated by suitable initial {\it Ansätze}, which are subsequently improved by means of a systematic iterative procedure. The multiplicative renormalization of the central equation is carried out following an approximate method, which is extensively employed in the studies of the standard quark gap equation. This approach amounts to the effective substitution of the vertex renormalization constants by kinematically simplified form factors of the three- and four-gluon vertices. The resulting numerical interplay, exemplified by the infrared suppression of the three-gluon vertex and the mild enhancement of the four-gluon vertex, is instrumental for obtaining positive-definite and monotonically decreasing running gluon masses. The resulting gluon propagators, put together from the gluon masses and kinetic terms obtained with this method, match rather accurately the data obtained from large-volume lattice simulations.

   hep-phhep-lathep-thPRD(2019)·37 citations
6. 06*

   Temperature Dependence of the Axion Mass in a Scenario Where the Restoration of Chiral Symmetry Drives the Restoration of the $U_A(1)$ Symmetry

   Davor Horvatić🇭🇷 · Dalibor Kekez🇭🇷 · Dubravko Klabučar🇭🇷

   The temperature ($T$) dependence of the axion mass is predicted for $T$'s up to $\sim 2.3\times$ the chiral restoration temperature of QCD. The axion is related to the $U_A(1)$ anomaly. The squared axion mass $m_a(T{)}^2$ is, modulo the presently undetermined scale of spontaneous breaking of Peccei-Quinn symmetry $f_a$ (squared), equal to QCD topological susceptibility $\chi (T)$ for all $T$. We obtain $\chi (T)$ by using quark condensates calculated in two effective Dyson-Schwinger models of nonperturbative QCD. They exhibit the correct chiral behavior, including the dynamical breaking of chiral symmetry and its restoration at high $T$. This is reflected in the $U_A(1)$ symmetry breaking and restoration through $\chi (T)$. In our previous studies, such $\chi (T)$ yields the $T$-dependence of the $U_A(1)$-anomaly-influenced masses of ${\eta }^{\prime }$ and $\eta$ mesons consistent with experiment. This in turn supports our prediction for the $T$-dependence of the axion mass. Another support is a rather good agreement with the pertinent lattice results. This agreement is not spoiled by our varying $u$ and $d$ quark mass parameters out of the isospin limit.

   hep-phnucl-thUniverse(2019)·8 citations
7. 07*

   Di-Higgs Peaks and Top Valleys: Interference Effects in Higgs Sector Extensions

   Philipp Basler🇩🇪 · Sally Dawson🇺🇸 · Christoph Englert🇬🇧 · Margarete Mühlleitner🇩🇪

   In models with extended scalars and CP violation, resonance searches in double Higgs final states stand in competition with related searches in top quark final states as optimal channels for the discovery of beyond the Standard Model (BSM) physics. This complementarity is particularly relevant for benchmark scenarios that aim to highlight multi-Higgs production as a standard candle for the study of BSM phenomena. In this note, we compare interference effects in $t\bar{t}$ final states with correlated phenomena in double Higgs production in the complex singlet and the complex 2-Higgs-Doublet Models. Our results indicate that the BSM discovery potential in di-Higgs searches can be underestimated in comparison to $t\bar{t}$ resonance searches. Top pair final states are typically suppressed due to destructive signal-background interference, while $hh$ final states can be enhanced due to signal-signal interference. For parameter choices where the two heavy Higgs resonances are well separated in mass, top final states are suppressed relative to the naive signal expectation, while estimates of the production cross section times branching ratio remain accurate at the $\mathcal{O}(10\%)$ level for double Higgs final states.

   hep-phhep-exPRD(2020)·35 citations
8. 08*

   Quark Wigner Distributions and GTMDs of Pion in the Light-Front Holographic Model

   Navdeep Kaur🇮🇳 · Harleen Dahiya🇮🇳

   We investigate the quark Wigner distributions of the pion to reveal the multidimensional picture of pion. We have used the spin improved wave functions of pion deduced from the light-front holographic model of mesons. By using the Fock-state overlap representation, the Wigner distributions of an unpolarized, longitudinally polarized and transversely polarized quark inside the pion are calculated. We have presented the results of transverse Wigner distributions in impact-parameter space as well as in momentum space. In order to understand the role of skewness which gives the longitudinal momentum transfer between the quarks, we study the six-dimensional phase-space distribution: the generalized transverse momentum dependent parton distributions of pion for the case of zero skewness as well as for nonzero value of skewness.

   hep-phEPJA(2020)·19 citations
9. 09*

   Towards a combined analysis of inclusive/exclusive electroproduction

   Astrid N. Hiller Blin🇩🇪 · Vitaly V. Chesnokov🇷🇺 · Victor I. Mokeev🇺🇸

   In view of the major advances achieved by the CLAS experiments in studying the N* electroexcitation amplitudes, as well as further extension of these studies in the experiments with CLAS12, we present an approach for the evaluation of the resonant contributions to inclusive electron scattering off protons. For the first time, the resonant contributions are determined from the experimental results on N* electrocouplings available from the data analyses of exclusive meson electroproduction off protons. This is a useful benchmark for future endeavours on understanding the transition region between low and high-energy regions, strongly related to tests on quark-hadron duality.

   hep-phnucl-thEPJ Web Conf.(2020)·1 citation
10. 10*

    A subtraction scheme for massive QED

    T. Engel🇨🇭 · A. Signer🇨🇭 · Y. Ulrich🇨🇭

    We present an extension of the FKS subtraction scheme beyond next-to-leading order to deal with soft singularities in fully differential calculations within QED with massive fermions. After a detailed discussion of the next-to-next-to-leading order case, we show how to extend the scheme to even higher orders in perturbation theory. As an application we discuss the computation of the next-to-next-to-leading order QED corrections to the muon decay and present differential results with full electron mass dependence.

    hep-phJHEP(2020)·49 citations
11. 11*

    Model-independent limits for anomalous triple gauge bosons $W^{+}{W}^{-}\gamma$ coupling at the CLIC

    A. A. Billur🇹🇷 · M. Köksal🇹🇷 · A. Gutiérrez-Rodríguez🇲🇽 · M. A. Hernández-Ruíz🇲🇽

    We investigate the potential of the Compact Linear Collider (CLIC) to probe the anomalous $W^{+}{W}^{-}\gamma$ coupling in $\gamma \gamma$, $\gamma {\gamma }^{\ast }$ and ${\gamma }^{\ast }{\gamma }^{\ast }$ collisions through the processes $\gamma \gamma \to W^{+}{W}^{-}$, $e^{+}\gamma \to e^{+}{\gamma }^{\ast }\gamma \to e^{+}{W}^{-}{W}^{+}$ and $e^{+}{e}^{-}\to e^{+}{\gamma }^{\ast }{\gamma }^{\ast }{e}^{-}\to e^{+}{W}^{-}{W}^{+}{e}^{-}$. We perform leptonic, semi-leptonic and hadronic decays channels for $W^{+}{W}^{-}$ production in the final state. Taking $\mathcal{L}=1\mathrm{a}{\mathrm{b}}^{-1}@\sqrt{s}=0.380\mathrm{TeV}$, $\mathcal{L}=2.5\mathrm{a}{\mathrm{b}}^{-1}@\sqrt{s}=1.5\mathrm{TeV}$ and $\mathcal{L}=5\mathrm{a}{\mathrm{b}}^{-1}@\sqrt{s}=3\mathrm{TeV}$, based on future CLIC data, the limits for $\Delta {\kappa }_{\gamma }$ and ${\lambda }_{\gamma }$ might reach up to $\mathcal{O}(10^{-5}-10^{-4})$ level in the most ideal with 5\hspace{0.8mm}$\mathrm{a}{\mathrm{b}}^{-1}$ set data, which shows a potential advantage compared to those from LHC, Tevatron and LEP data. Thus, our results represent that the processes $\gamma \gamma \to W^{+}{W}^{-}$, $e^{+}\gamma \to e^{+}{\gamma }^{\ast }\gamma \to e^{+}{W}^{-}{W}^{+}$ and $e^{+}{e}^{-}\to e^{+}{\gamma }^{\ast }{\gamma }^{\ast }{e}^{-}\to e^{+}{W}^{-}{W}^{+}{e}^{-}$ at the CLIC are a very good prospect for probing the anomalous $W^{+}{W}^{-}\gamma$ couplings.

    hep-phEur.Phys.J.Plus(2021)·18 citations
12. 12*

    Scalar mesons in the chiral theory with quark degrees of freedom

    M. S. Lukashov🇷🇺 · Yu. A. Simonov🇷🇺

    The Chiral Confining Lagrangian, based on the chiral theory with quark degrees of freedom, is used to study the spectroscopy of scalar mesons. The formalism does not contain arbitrary fitting parameters and takes into account infinite number of transitions from meson-meson to quark-antiquark states. Starting from known $q\bar{q}$ poles the transition coefficients ensure the strong shift of the poles for the $\pi \pi$ and much smaller shift for the $K\bar{K}$ systems. The resulting amplitudes $f_{\pi \pi }$ and $f_{K\bar{K}}$ are calculated in terms of the $q\bar{q}$ and the free meson Green's functions. With the account of the $\pi \pi /K\bar{K}$ channel coupling one obtains two resonances: a wide resonance $E_1$ in the range 500-700 MeV and narrow $E_2$ near 1 GeV, which can be associated with $f_0(500)$ and $f_0(980)$. A similar analysis, applied to the $I=1$ channel, shows that in this case two very close poles in different sheets appear near $E=980$ MeV, which can be associated with the $a_0(980)$ resonance. The obtained $\pi \pi$ interaction amplitudes, $\mathrm{Re}{f}_{\pi \pi }(E)$ and $\mathrm{Im}{f}_{\pi \pi }(E)$ are compared with the known data.

    hep-phhep-exPRD(2020)·7 citations
13. 13*

    Testing Lorentz-symmetry violation via electroweak decays

    Y. M. P. Gomes🇧🇷 · P. C. Malta🇧🇷 · M. J. Neves🇧🇷

    In this work we introduce CPT-odd non-minimal Lorentz-symmetry violating couplings to the electroweak sector modifying the interaction between leptons and gauge bosons. The vertex rules allow us to calculate tree-level processes modified by the presence of the novel dimension-five operators. For definitiveness, we investigate the $W$ decay into a lepton-neutrino pair, the $Z$ decay into pairs of charged and neutral leptons, as well as the decay of the muon. By comparing the experimental measurements on these processes to our results we are able to bound several combinations of the background 4-vectors to be $\lesssim 10^{-4}\text{mbox}{GeV}^{-1}$.

    hep-phPRD(2020)·12 citations
14. 14*

    Three flavor neutrino conversions in supernovae: Slow $\&$ Fast instabilities

    Madhurima Chakraborty🇮🇳 · Sovan Chakraborty🇮🇳

    Self induced neutrino flavor conversions in the dense regions of stellar core collapse are almost exclusively studied in the standard two flavor scenario. Linear stability analysis has been successfully used to understand these flavor conversions. This is the first linearized study of $\text{three flavor}$ fast instabilities. The `fast' conversions are fascinating distinctions of the dense neutrino systems. In the fast modes the collective oscillation dynamics are independent of the neutrino mass, growing at the scale of the large neutrino-neutrino interaction strength ($10^5$ km${}^{-1}$) of the dense core. This is extremely fast, in comparison to the usual `slow' collective modes driven by much smaller vacuum oscillation frequencies ($10^0$ km${}^{-1}$). The three flavor analysis shows distinctive characteristics for both the slow and the fast conversions. The slow oscillation results are in qualitative agreement with the existing nonlinear three flavor studies. For the fast modes, addition of the third flavor opens up possibilities of influencing the growth rates of flavor instabilities when compared to a two flavor scenario.

    hep-phastro-ph.HEJCAP(2020)·68 citations
15. 15*

    The Multiple Point Principle and Extended Higgs Sectors

    John McDowall🇬🇧 · David J Miller🇬🇧

    The Higgs boson quartic self-coupling in the Standard Model appears to become zero just below the Planck scale, with interesting implications to the stability fo the Higgs vacuum at high energies. We review the Multiple Point Principle that suggests the quartic self-coupling should vanish exactly at the Planck scale. Although this vanishing is not consistent with the Standard Model, we investigate Higgs sectors extended with additional states to test whether one may satisfy the high scale boundary condition while maintaining the observed Higgs mass. We also test these scenarios to ensure the stability of the vacuum at all energies below the the Planck scale and confront them with experimental results from the LHC and Dark Matter experiments.

    hep-phFront.in Phys.(2019)·7 citations
16. 16*

    Neutrino Oscillations in Dark Matter

    Ki-Young Choi🇰🇷 · Eung Jin Chun🇰🇷 · Jongkuk Kim🇰🇷

    We study neutrino oscillations in a medium of dark matter which generalizes the standard matter effect. A general formula is derived to describe the effect of various mediums and their mediators to neutrinos. Neutrinos and anti-neutrinos receive opposite contributions from asymmetric distribution of (dark) matter and anti-matter, and thus it could appear in precision measurement of neutrino or anti-neutrino oscillations. Furthermore, the standard neutrino oscillation can occur from the symmetric dark matter effect even for massless neutrinos.

    hep-phastro-ph.HEhep-exPhys.Dark Univ.(2020)·51 citations
17. 17*

    Global fluid fits to identified particle transverse momentum spectra from heavy-ion collisions at the Large Hadron Collider

    D. Devetak🇩🇪 · A. Dubla🇩🇪 · S. Floerchinger🇩🇪 · E. Grossi🇩🇪 · S. Masciocchi🇩🇪 · A. Mazeliauskas🇨🇭 · I. Selyuzhenkov🇩🇪

    Transverse momentum spectra of identified particles produced in heavy-ion collisions at the Large Hadron Collider are described with relativistic fluid dynamics. We perform a systematic comparison of experimental data for pions, kaons and protons up to a transverse momentum of 3 GeV$/c$ with calculations using the FluiduM code package to solve the evolution equations of fluid dynamics, the TrENTo model to describe the initial state and the FastReso code to take resonance decays into account. Using data in five centrality classes at the center-of-mass collision energy per nucleon pair $\sqrt{s_{\text{NN}}}=2.76\text{TeV}$, we determine systematically the most likely parameters of our theoretical model including the shear and bulk viscosity to entropy ratios, the initialization time, initial density and freeze-out temperature through a global search and quantify their posterior probability. This is facilitated by the very efficient numerical implementation of FluiduM and FastReso. Based on the most likely model parameters we present predictions for the transverse momentum spectra of multi-strange hadrons as well as identified particle spectra from Pb-Pb collisions at $\sqrt{s_{\text{NN}}}=5.02\text{TeV}$.

    hep-phnucl-exnucl-thJHEP(2020)·50 citations
18. 18*

    Observing EeV neutrinos through the Earth: GZK and the anomalous ANITA events

    Ibrahim Safa🇺🇸 · Alex Pizzuto🇺🇸 · Carlos Argüelles🇺🇸 · Francis Halzen🇺🇸 · Raamis Hussain🇺🇸 · Ali Kheirandish🇺🇸 · Justin Vandenbroucke🇺🇸

    Tau neutrinos are unique cosmic messengers, especially at extreme energies. When they undergo a charged-current interaction, the short lifetime of the produced tau gives rise to secondary tau neutrinos that carry a significant fraction of the primary neutrino energy. This effect, known as tau neutrino regeneration, has not been applied to its full potential in current generation neutrino experiments. In this work, we present an updated calculation of tau neutrino regeneration, and explore its implications for two scenarios: the recent anomalous ANITA events and the cosmogenic neutrino flux. For the former, we investigate the idea of localized emission and find that the maximum secondary neutrino flux allowed by IceCube measurements implies a primary flux that is incompatible with the ANITA observation, regardless of the assumed source energy spectrum. For the latter, we study the prospect of detecting the cosmogenic neutrino flux of regenerated PeV neutrinos with current and next generation neutrino detectors.

    hep-phastro-ph.HEhep-exJCAP(2020)·50 citations
19. 19*

    Probing Doubly and Singly Charged Higgs at $pp$ Collider HE-LHC

    Rojalin Padhan🇮🇳 · Debottam Das🇮🇳 · Manimala Mitra🇮🇳 · Aruna Kumar Nayak🇮🇳

    We analyse the signal sensitivity of multi-lepton final states at collider that can arise from doubly and singly charged Higgs decay in a type-II seesaw framework. We assume triplet vev to be very small and degenerate masses for both the charged Higgs states. The leptonic branching ratio of doubly and singly charged Higgs states have a large dependency on the neutrino oscillation parameters, lightest neutrino mass scale, as well as neutrino mass hierarchy. We explore this as well as the relation between the leptonic branching ratios of the singly and doubly charged Higgs states in detail. We evaluate the effect of these uncertainties on the production cross-section. Finally, we present a detailed analysis of multi-lepton final states for a future hadron collider HE-LHC, that can operate with center of mass energy $\sqrt{s}=27$ TeV.

    hep-phhep-exPRD(2020)·41 citations
20. 20*

    Light and Heavy Mesons in The Complex Mass Scheme

    Mikhail N. Sergeenko🇧🇾

    Mesons containing light and heavy quarks are studied. Interaction of quarks is described by the funnel-type potential with the distant dependent strong coupling, ${\alpha }_{\S }(r)$. Free particle hypothesis for the bound state is developed: quark and antiquark move as free particles in of the bound system. Relativistic two-body wave equation with position dependent particle masses is used to describe the flavored $Qq$ systems. Solution of the equation for the system in the form of a~standing wave is given. Interpolating complex-mass formula for two exact asymptotic eigenmass expressions is obtained. Mass spectra for some leading-state flavored mesons are calculated.

    hep-ph5 citations
21. 21*

    Higgs field in cosmology

    Christian F. Steinwachs🇩🇪

    The accelerated expansion of the early universe is an integral part of modern cosmology and dynamically realized by the mechanism of inflation. The simplest theoretical description of the inflationary paradigm is based on the assumption of an additional propagating scalar degree of freedom which drives inflation - the inflaton. In most models of inflation the fundamental nature of the inflaton remains unexplained. In the model of Higgs inflation, the inflaton is identified with the Standard Model Higgs boson and connects cosmology with elementary particle physics. A characteristic feature of this model is a non-minimal coupling of the Higgs boson to gravity. I review and discuss several phenomenological and fundamental aspects of this model, including the impact of quantum corrections and the renormalization group, the derivation of initial conditions for Higgs inflation in a quantum cosmological framework and the classical and quantum equivalence of different field parametrizations.

    hep-phastro-ph.COgr-qchep-thFundam.Theor.Phys.(2020)·17 citations
22. 22*

    Differential Top Quark Pair Production at the LHC: Challenges for PDF Fits

    Shaun Bailey🇬🇧 · Lucian Harland-Lang🇬🇧

    We present the results of a PDF fit to differential top quark production within the MMHT framework. We in particular consider ATLAS data in the lepton + jet and dilepton channels and CMS data in the lepton + jet channel, at 8 TeV. While the fit quality to the ATLAS dilepton data is good, for the CMS case we see some issues in achieving a good fit quality for certain distributions. However, we focus on the ATLAS lepton + jet data, for which correlations of the statistical and systematic errors are provided across the four relevant distributions for PDF determination, namely $p_T^t$, $M_{tt}$, $y_t$ and $y_{tt}$. We find severe difficulties in fitting these distributions simultaneously, with particular sensitivity to the precise degree of correlation taken between the dominant two--point MC uncertainties in the data. We investigate the effect of some reasonable decorrelation of these uncertainties, finding the impact on the fit quality to be significant and the resultant gluon not negligible. This is in particular found to be larger than the effect of including NNLO QCD and NLO EW corrections in the top quark pair production cross section on the fit, motivating a closer understanding of the physics underlying these errors sources and in particular the uncertainty on the degree of correlation in them.

    hep-phEPJC(2020)·46 citations
23. 23*

    $B_{(s)}\to {\eta }_c(P,V)$ decays and effects of the next-to-leading order contributions in the perturbative QCD approach

    Zhen-Jun Xiao🇨🇳 · Da-Cheng Yan🇨🇳 · Xin Liu🇨🇳

    By employing the perturbative QCD (PQCD) factorization approach, we studied the sixteen $B/B_s\to {\eta }_c(\pi ,K,{\eta }^{(\prime )},\rho ,K^{\ast },\omega ,\varphi )$ decays with the inclusion of the currently known next-to-leading order (NLO) contributions. We found the following main points: (a) for the five measured $B\to {\eta }_c(K,K^{\ast })$ and $B_s\to {\eta }_c\varphi$ decays, the NLO contributions can provide $(80-180)\%$ enhancements to the leading order (LO) PQCD predictions of their branching ratios, which play an important role to help us to interpret the data; (b) for the seven ratios $R_{1,\cdots ,7}$ of the branching ratios defined among the properly selected pair of the considered decay modes, the PQCD predictions for the values of $R_{3,4,5}$ agree well with those currently available measurements from BaBar and Belle Collaboration; (c) for $B^0\to {\eta }_c{K}_S^0$ decay, the PQCD predictions for both the direct and mixing induced CP asymmetries do agree very well with the measured values within errors; and (d) the PQCD predictions for ratios $R_{1,2}$ and $R_{6,7}$ also agree with the general expectations and will be tested by the future experiments.

    hep-phhep-exNPB(2020)·8 citations
24. 24*

    QCD Corrections in SMEFT Fits to $WZ$ and $WW$ Production

    Julien Baglio🇩🇪 · Sally Dawson🇺🇸 · Samuel Homiller🇺🇸

    We investigate the role of anomalous gauge boson and fermion couplings on the production of $WZ$ and $W^{+}{W}^{-}$ pairs at the LHC to NLO QCD in the Standard Model effective field theory, including dimension-6 operators. Our results are implemented in a publicly available version of the POWHEG-BOX. We combine our $WZ$ results in the leptonic final state $e\nu {\mu }^{+}{\mu }^{-}$ with previous $W^{+}{W}^{-}$ results to demonstrate the numerical effects of NLO QCD corrections on the limits on effective couplings derived from ATLAS and CMS 8 and 13 TeV differential measurements. Our study demonstrates the importance of including NLO QCD SMEFT corrections in the $WZ$ analysis, while the effects on $WW$ production are smaller. We also show that the $\mathcal{O}(1/{\Lambda }^4)$ contributions dominate the analysis, where $\Lambda$ is the high energy scale associated with the SMEFT.

    hep-phhep-exPRD(2019)·59 citations
25. 25*

    Non-Minimal M-flation

    Amjad Ashoorioon🇮🇷 · Kazem Rezazadeh🇮🇷

    We show how in a matrix inflationary model in which there is a non-minimal coupling between the matrix inflatons and gravity --hence dubbed Non-$\text{MM}$-flation-- some of the disadvantages of the minimal model can be avoided. In particular, the number of D3 branes can be reduced substantially to $\lesssim \mathcal{O}(100)$, which can alleviate the ``potential'' backreaction problem of large number of D3 branes on the background geometry. This is achieved by values of non-minimal coupling of order few hundred, which is much smaller than that of Higgs Inflation. The prediction of the model in the symmetry breaking part of the potential, which is a local attractor and can support eternal inflation, is compatible with the latest PLANCK results. In contrast to the minimal model, the spectator fields can partially or completely reheat the universe, depending on the symmetry-breaking vacuum expectation value and the non-minimal coupling parameter. We also comment on how the presence of gauge species keep the UV cutoff at around the Planck scale in the Einstein frame and, in contrast to the Higgs inflation, the problem of field displacements beyond the cutoff does not occur.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2020)·7 citations
26. 26*

    Planck Scale from Broken Local Conformal Invariance in Weyl Geometry

    Ichiro Oda🇯🇵

    It is shown that in the quadratic gravity based on Weyl's conformal geometry, the Planck mass scale can be generated from quantum effects of the gravitational field and the Weyl gauge field via the Coleman-Weinberg mechanism where a local scale symmetry, that is, conformal symmetry, is broken. At the same time, the Weyl gauge field acquires mass less than the Planck mass by absorbing the dilaton. The shape of the effective potential is almost flat owing to a gravitational character and high symmetries, so our model would provide an attractive model for the inflationary universe. We also present a toy model showing spontaneous symmetry breakdown of a scale symmetry by moving from the Jordan frame to the Einstein one, and point out its problem.

    ↳ hep-thgr-qchep-phAdv.Stud.Theor.Phys.(2020)·12 citations
27. 27*

    Contributions of the LAGO Collaboration to the 36th ICRC

    A. Alberto · W. Alvarez · L. Ancari · M. Andrade Uzieda · R. Arceo · O. Areso · L.H. Arnaldi · H. Asorey · M. Audelo · E. Berazaín · X. Bertou · M. J. Bonilla-Rosales and 81 other authors

    The LAGO (Latin American Giant Observatory) observatory is an experiment that spans over Latin America in a wide range of latitudes that gives different rigidity cut offs for the enter of cosmic rays in the atmosphere. The motivation of the Observatory is to study atmospheric radiation and space weather through the measurement of the secondary emission of low energy cosmic rays at ground level using Water Cherenkov Detectors (WCD). This work presents the contributions of the LAGO collaboration to the 2019 36th ICRC.

    ↳ hep-exhep-ph0 citations
28. 28*

    Gravitational waves from first order cosmological phase transitions in the Sound Shell Model

    Mark Hindmarsh🇫🇮 · Mulham Hijazi🇬🇧

    We calculate gravitational wave power spectra from first order early Universe phase transitions using the Sound Shell Model. The model predicts that the power spectrum depends on the mean bubble separation, the phase transition strength, the phase boundary speed, with the overall frequency scale set by the nucleation temperature. There is also a dependence on the time evolution of the bubble nucleation rate. The gravitational wave peak power and frequency are in good agreement with published numerical simulations, where bubbles are nucleated simultaneously. Agreement is particularly good for detonations, but the total power for deflagrations is predicted higher than numerical simulations show, indicating refinement of the model of the transfer of energy to the fluid is needed for accurate computations. We show how the time-dependence of the bubble nucleation rate affects the shape of the power spectrum: an exponentially rising nucleation rate produces higher amplitude gravitational waves at a longer wavelength than simultaneous nucleation. We present an improved fit for the predicted gravitational wave power spectrum in the form of a double broken power law, where the two breaks in the slope happen at wavenumber corresponding to the mean bubble separation and the thickness of the fluid shell surrounding the expanding bubbles, which in turn is related to the difference of the phase boundary speed from the speed of sound.

    ↳ astro-ph.COhep-phJCAP(2019)·259 citations
29. 29*

    Consistency checks for two-body finite-volume matrix elements: I. Conserved currents and bound states

    Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇨🇭 · Andrew W. Jackura🇺🇸

    Recently, a framework has been developed to study form factors of two-hadron states probed by an external current. The method is based on relating finite-volume matrix elements, computed using numerical lattice QCD, to the corresponding infinite-volume observables. As the formalism is complicated, it is important to provide non-trivial checks on the final results and also to explore limiting cases in which more straightforward predications may be extracted. In this work we provide examples on both fronts. First, we show that, in the case of a conserved vector current, the formalism ensures that the finite-volume matrix element of the conserved charge is volume-independent and equal to the total charge of the two-particle state. Second, we study the implications for a two-particle bound state. We demonstrate that the infinite-volume limit reproduces the expected matrix element and derive the leading finite-volume corrections to this result for a scalar current. Finally, we provide numerical estimates for the expected size of volume effects in future lattice QCD calculations of the deuteron's scalar charge. We find that these effects completely dominate the infinite-volume result for realistic lattice volumes and that applying the present formalism, to analytically remove an infinite-series of leading volume corrections, is crucial to reliably extract the infinite-volume charge of the state.

    ↳ hep-lathep-phnucl-thPRD(2019)·39 citations
30. 30*

    Neutron Star Structure in the Minimal Gravitational Standard-Model Extension and the Implication to Continuous Gravitational Waves

    Rui Xu🇨🇳 · Junjie Zhao🇨🇳 · Lijing Shao🇨🇳

    Tiny violation of Lorentz invariance has been the subject of theoretic study and experimental test for a long time. We use the Standard-Model Extension (SME) framework to investigate the effect of the minimal Lorentz violation on the structure of a neutron star. A set of hydrostatic equations with modifications from Lorentz violation are derived, and then the modifications are isolated and added to the Tolman-Oppenheimer-Volkoff (TOV) equation as the leading-order Lorentz-violation corrections in relativistic systems. A perturbation solution to the leading-order modified TOV equations is found. The quadrupole moments due to the anisotropy in the structure of neutron stars are calculated and used to estimate the quadrupole radiation of a spinning neutron star with the same deformation. The calculation puts forward a new test for Lorentz invariance in the strong-field regime when continuous gravitational waves are observed in the future.

    ↳ gr-qcastro-ph.HEhep-phPLB(2020)·16 citations
31. 31*

    Mass fluctuations and absorption rates in Dirac materials sensors

    Bart Olsthoorn🇸🇪 · Alexander V. Balatsky🇸🇪

    We study the mass fluctuations in gapped Dirac materials by treating the mass-term as both a continuous and discrete random variable. Gapped Dirac materials were proposed to be used as materials for Dark matter sensors. One thus would need to estimate the role of disorder and fluctuations on the interband absorption of dark matter. We find that both continuous and discrete fluctuations across the sample introduce tails (e.g. Lifshitz tails) in the density of states and the interband absorption rate. We estimate the strength of the gap filling and discuss implications of these fluctuations on the performance as sensors for Dark matter detection. The approach used in this work provides a basic framework to model the disorder by any arbitrary mechanism on the interband absorption of Dirac material sensors.

    ↳ cond-mat.mtrl-scihep-phPRB(2020)·1 citation
32. 32*

    Logarithmic loop corrections, moduli stabilisation and de Sitter vacua in string theory

    Ignatios Antoniadis🇫🇷 · Yifan Chen🇫🇷 · George K. Leontaris🇬🇷

    We study string loop corrections to the gravity kinetic terms in type IIB compactifications on Calabi-Yau threefolds or their orbifold limits, in the presence of $D7$-branes and orientifold planes. We show that they exhibit in general a logarithmic behaviour in the large volume limit transverse to the $D7$-branes, induced by a localised four-dimensional Einstein-Hilbert action that appears at a lower order in the closed string sector, found in the past. Here, we compute the coefficient of the logarithmic corrections and use them to provide an explicit realisation of a mechanism for Kähler moduli stabilisation that we have proposed recently, which does not rely on non-perturbative effects and lead to de Sitter vacua. Our result avoids no-go theorems of perturbative stabilisation due to runaway potentials, in a way similar to the Coleman-Weinberg mechanism, and provides a counter example to one of the swampland conjectures concerning de Sitter vacua in quantum gravity, once string loop effects are taken into account; it thus paves the way for embedding the Standard Model of particle physics and cosmology in string theory.

    ↳ hep-thgr-qchep-phJHEP(2020)·86 citations
33. 33*

    Waveform of gravitational waves in the general parity-violating gravities

    Wen Zhao🇨🇳 · Tao Zhu🇨🇳 · Jin Qiao🇨🇳 · Anzhong Wang🇺🇸

    As an extension of our previous work [J.Qiao, T.Zhu, W.Zhao & A.Wang, arXiv:1909.03815], in this article, we calculate the effects of parity violation on gravitational-wave (GW) waveforms during their propagation in the most general parity-violating gravities, including Chern-Simons modified gravity, ghost-free scalar-tensor gravity, symmetric teleparallel equivalence of GR theory, Hořava-Lifshitz gravity and so on. For this purpose, we consider the GWs generated by the coalescence of compact binaries and concentrate on the imprints of the parity violation in the propagation of GWs. With a unified description of GW in the theories of parity-violating gravity, we study the effects of velocity and amplitude birefringence on the GW waveforms. Decomposing the GWs into the circular polarization modes, the two birefringence effects exactly correspond to the modifications in phase and amplitude of GW waveforms respectively. We find that, for each circular polarization mode, the amplitude, phase and velocity of GW can be modified by both the parity-violating terms and parity-conserving terms in gravity. Therefore, in order to test the parity symmetry in gravity, we should compare the difference between two circular polarization modes, rather than measuring an individual mode. Combining two circular modes, we obtain the GW waveforms in the Fourier domain, and obtain the deviations from those in General Relativity. The GW waveforms derived in this paper are also applicable to the theories of parity-conserving gravity, which have the modified dispersion relations (e.g. massive gravity, double special relativity theory, extra-dimensional theories, etc), or/and have the modified friction terms (e.g. nonlocal gravity, gravitational theory with time-dependent Planck mass, etc).

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2020)·113 citations
34. 34*

    A new magnetic monopole inspired by Berry's phase

    Shinichi Deguchi🇯🇵 · Kazuo Fujikawa🇯🇵

    A new static and azimuthally symmetric magnetic monopolelike object, which looks like a Dirac monopole when seen from far away but smoothly changes to a dipole near the monopole position and vanishes at the origin, is discussed. This monopolelike object is inspired by an analysis of an exactly solvable model of Berry's phase in the parameter space. A salient feature of the monopolelike potential ${\mathcal{A}}_k(r,\theta )$ with a magnetic charge $e_M$ is that the Dirac string is naturally described by the potential ${\mathcal{A}}_k(r,\theta )$, and the origin of the Dirac string and the geometrical center of the monopole are displaced in the coordinate space. The smooth topology change from a monopole to a dipole takes place if the Dirac string, when coupled to the electron, becomes unobservable by satisfying the Dirac quantization condition. The electric charge is then quantized even if the monopole changes to a dipole near the origin. In the transitional region from a monopole to a dipole, a half-monopole with a magnetic charge $e_M/2$ appears.

    ↳ hep-thcond-mat.mes-hallhep-phPLB(2020)·6 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.