Thu·Jul 4, 2019Thursday·July 4, 2019

1. 01*

   The interplay between SM precision, BSM physics and measurements of ${\alpha }_{\mathrm{had}}$ in $\mu$-$e$ scattering

   Ulrich Schubert🇺🇸 · Ciaran Williams🇺🇸

   Muon electron scattering experiments such as the proposed MUonE experiment, offer an opportunity for an improved measurement of the Leading Order hadronic running of $\alpha$, denoted $\Delta {\alpha }_{\mathrm{had}}$. Such a measurement could be utilized to reduce the theoretical uncertainty on the prediction of the anomalous magnetic moment of the muon, $g-2$. Currently there is a discrepancy between theory and data for this observable which could potentially be explained by Beyond the Standard Model (BSM) physics. Here we investigate the possible impact of missing Standard Model (SM) higher order corrections and BSM physics on the proposed measurement of $\Delta {\alpha }_{\mathrm{had}}$. In principle either could be indirectly fitted into $\Delta {\alpha }_{\mathrm{had}}$, causing inconsistencies if used in a $g-2$ application. The literature suggests a target of 10 ppm on the cross section for the theoretical accuracy. We assess the validity of this target in detail using a variety of methods, finding that a 1 ppm target is a more conservative estimate to ensure missing higher orders do not dominate the theoretical uncertainty. For the potential BSM contributions we study various models which contribute first at tree- and loop-level. Of particular interest is the impact from dark photon models, which can potentially affect the measurement of $\Delta {\alpha }_{\mathrm{had}}$ at the desired accuracy. At loop-level there exists in general a kinematic suppression adequate to reduce the BSM contributions to a level which can be neglected for the extraction of $\Delta {\alpha }_{\mathrm{had}}$.

   hep-phPRD(2019)·9 citations
2. 02*

   Impacts of radiative corrections on measurements of lepton flavour universality in $B\to D\ell {\nu }_{\ell }$ decays

   Suzanne Klaver🇮🇹

   Radiative corrections to $B\to D\ell {\nu }_{\ell }$ decays can have an impact on predictions and measurements of the lepton universality ratios $\mathcal{R}(D^{+})$ and $\mathcal{R}(D^0)$. These proceedings summarise a study on the comparison between recent calculations of soft-photon corrections on these ratios and the corrections simulated by the PHOTOS package. Also the impact of Coulomb interactions, not simulated in PHOTOS, is discussed. Using pseudo-experiments, the effect of high-energy photon emission is studied in an LHCb-like environment, showing a bias of up to 7\% on measurements of $\mathcal{R}(D)$.

   hep-phhep-ex1 citation
3. 03*

   Renormalization in Nonminimal Lorentz-Violating Field Theory

   J.R. Nascimento🇧🇷 · A.Yu. Petrov🇧🇷 · C.M. Reyes🇨🇱

   We provide the first step towards renormalization in a nonminimal Lorentz-violating model consisting of normal scalars and modified fermions with mass dimension five operators. We compute the radiative corrections corresponding to the scalar self-energy, and we show that some divergencies are improved and in the scalar sector they are finite. The pole mass of the scalar two-point function is found and shown to lead to modifications of asymptotic states.

   hep-phhep-th1 citation
4. 04*

   Dark Matter Spin-Spin Interaction through the Pseudo-Scalar Vacuum Field

   Alexander I Nesterov🇲🇽 · Gennady P Berman🇺🇸 · Vladimir Tsifrinovich🇺🇸 · Xidi Wang🇺🇸 · Marco Merkli🇨🇦

   We suggest that the pseudo-scalar vacuum field (PSV) in the dark matter (DM) sector of the Universe may be as important as the electromagnetic vacuum field in the baryonic sector. In particular, the spin-spin interaction between the DM fermions, mediated by PSV, may represent the strongest interaction between the DM fermions due to the absence of the electric charge and the magnetic dipole moment. Based on this assumption, we consider the influence of the spin-spin interaction, mediated by PSV, on the spin precession of the DM fermions (e. g. neutralino). In the secular approximation, we obtain the exact expression describing the frequency of the precession and estimate the decoherence rate.

   hep-phMod.Phys.Lett.A(2020)·0 citations
5. 05*

   Lepton (non-) unversality in (flavor changing) neutral current B decays

   Rodrigo Alonso🇯🇵

   The following proceedings contain a theory perspective on the flavor changing neutral current anomalies reported by LHCb on the ratios $B\to K^{(\ast )}\mu \mu /B\to K^{(\ast )}ee$

   hep-ph0 citations
6. 06*

   Doubly Blind Spots in Scalar Dark Matter Models

   Wolfgang Altmannshofer🇺🇸 · Brian Maddock🇺🇸 · Stefano Profumo🇺🇸

   We consider a framework where the Standard Model is augmented by a second SU(2) scalar doublet and by a real scalar singlet that, protected by a Z2 symmetry, provides a particle Dark Matter candidate. We show that this setup allows for doubly blind spots at both collider searches for anomalies in the Higgs invisible decay width, and at direct Dark Matter detection. The blind spots originate from cancellations between interfering diagrams featuring different neutral scalar exchanges, and from cancellations driven by the two-Higgs doublet structure in the vertex coupling the singlet state with the Standard-Model-like Higgs. We demonstrate that the blind spots arise in a wide and generic array of realizations for the two-Higgs doublet model, including scenarios with a non-trivial flavor structure. We provide analytical formulæ that describe the location of the blind spots in the theory parameter space, and we discuss the resulting phenomenology.

   hep-phPRD(2019)·8 citations
7. 07*

   Cho decomposition, Abelian gauge fixing and monopoles in G(2) Yang-Mills theory

   Zeinab Dehghan🇮🇷 · Sedigheh Deldar (University of Tehran)🇮🇷

   By extending the Cho decomposition method to G(2) gauge group, monopoles of this group are studied. Since SU(2) and SU(3) are subgroups of G(2), discussions are done mostly based on these subgroups of G(2). A direct relation between root vectors of G(2) and the associated magnetic charges is presented by group theoretical issues. In addition, G(2) monopoles are obtained by an Abelian gauge fixing method, and it is shown that the results agree with the ones we obtain by the Cho decomposition method.

   hep-phPRD(2019)·4 citations
8. 08*

   Pion form factor and low-energy hadronic contribution to muon $g-2$ by analytic extrapolation: consistency and sensitivity tests

   B. Ananthanarayan🇮🇳 · I. Caprini🇷🇴 · D. Das🇮🇳

   The largest error in the theoretical determination of the muon anomalous magnetic moment is due to the low-energy hadronic vacuum polarization, which cannot be calculated by perturbative QCD and requires nonperturbative techniques. Recently, an accurate determination of the low-energy two-pion contribution to muon $g-2$ has been obtained by a parametrization-free analytic continuation of the pion vector form factor from other kinematical regions. In this work we compare the results of the analytic continuation with direct determinations at low momenta from experiment and lattice QCD. We also explore the sensitivity of the method to the timelike data on the modulus of the form factor used as input, by extending the input region to energies up to 0.76 GeV.

   hep-phRom.J.Phys.(2019)·3 citations
9. 09*

   Thermal behaviors of light scalar resonances at low temperatures

   Rui Gao🇨🇳 · Zhi-Hui Guo🇨🇳 · Jin-Yi Pang🇩🇪

   We study the thermal properties of the lowest multiplet of the QCD light-flavor scalar resonances, including the $f_0(500)/\sigma$, $K_0^{\ast }(700)/\kappa$, $f_0(980)$ and $a_0(980)$, in the framework of unitarized $U(3)$ chiral perturbation theory. After the successful fits to the meson-meson scattering inputs, such as the phase shifts and inelasticities, we obtain the unknown parameters and further calculate the resonance poles and their residues at zero temperature. By including the finite-temperature effects in the unitarized meson-meson scattering amplitudes, the thermal behaviors of the scalar resonance poles in the complex energy plane are studied. The masses of $\sigma$ and $\kappa$ are found to considerably decrease when increasing the temperatures, while their widths turn out to be still large when the temperatures reach around $200$ MeV. In contrast, both the masses and widths of the $f_0(980)$ and $a_0(980)$ are only slightly changed.

   hep-phhep-latnucl-thPRD(2019)·18 citations
10. 10*

    Three regimes of QCD

    L. Ya. Glozman🇦🇹

    While the QCD Lagrangian as the whole is only chirally symmetric, its electric part has larger chiral-spin SU(2)_{CS} and SU(2N_F) symmetries. This allows separation of the electric and magnetic interactions in a given reference frame. Artificial truncation of the near-zero modes of the Dirac operator results in the emergence of the SU(2)_{CS} and SU(2N_F) symmetries in hadron spectrum. This implies that while the confining electric interaction is distributed among all modes of the Dirac operator, the magnetic interaction is located at least predominantly in the near-zero modes. Given this observation one could anticipate that above the pseudocritical temperature, where the near-zero modes of the Dirac operator are suppressed, QCD is SU(2)_{CS} and SU(2N_F) symmetric, which means absence of deconfinement in this regime. Solution of the N_F=2 QCD on the lattice with a chirally symmetric Dirac operator reveals that indeed in the interval Tc - 3Tc QCD is approximately SU(2)_{CS} and SU(2N_F) symmetric which implies that degrees of freedom are chirally symmetric quarks bound by the chromoelectric field into color-singlet objects without the chromomagnetic effects. This regime is referred to as a Stringy Fluid. At larger temperatures this emergent symmetry smoothly disappears and QCD approaches the Quark-Gluon Plasma regime with quasifree quarks. The Hadron Gas, the Stringy Fluid and the Quark-Gluon Plasma differ by symmetries, degrees of freedom and properties.

    hep-phhep-lathep-thnucl-thInt.J.Mod.Phys.A(2021)·15 citations
11. 11*

    Boundedness from below in the $U(1)\times U(1)$ three-Higgs-Doublet model

    Francisco S. Faro🇵🇹 · Igor P. Ivanov🇵🇹

    Establishing if multi-Higgs potentials are bounded from below (BFB) can be rather challenging, and it may impede efficient investigation of all phenomenological consequences of such models. In this paper, we find the necessary and sufficient BFB conditions for the Three-Higgs-Doublet model (3HDM) with the global symmetry group $U(1)\times U(1)$. We observed an important role played by charge-breaking directions in the Higgs space, even for situations when a good-looking neutral minimum exists. This remark is not limited to the particular model we consider but represents a rather general feature of elaborate multi-Higgs potentials which must be carefully dealt with. Also, applying this method to Weinberg's model (the ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ symmetric 3HDM) turned out to be more challenging than was believed in the literature. In particular, we have found that the approach taken in a paper from 2009 does not lead to the necessary and sufficient BFB conditions for this case.

    hep-phPRD(2019)·51 citations
12. 12*

    Unified Description of Multiplicity Distributions and Bose-Einstein Correlations at the LHC Based on the Three-Negative Binomial Distribution

    Minoru Biyajima🇯🇵 · Takuya Mizoguchi🇯🇵

    Using the Monte Carlo data at 7 TeV collected by the ATLAS collaboration (PYTHIA 6), we examine the necessity of applying the three-negative binomial distribution (T-NBD). By making use of the T-NBD formulation, we analyze the multiplicity distribution (MD) and the Bose-Einstein correlation (BEC) at the Large Hadron Collider (LHC). In the T-NBD framework, the BEC is expressed by two degrees of coherence ${\lambda }_1$ and ${\lambda }_2$ and two kinds of exchange functions $E_1^2$ and $E_2^2$ that act over interaction ranges $R_1$ and $R_2$, respectively. Using the calculated ${\lambda }_1$ and ${\lambda }_2$ based on the T-NBD, along with free ${\lambda }_1$ and ${\lambda }_2$, we analyze the BEC data at 0.9 and 7 TeV. The estimated parameters $R_1$ and $R_2$ are almost coincident and seem to be consistent with $pp$ collisions. We also present an enlarged Koba-Nielsen-Olesen (KNO) scaling function based on the T-NBD, and apply it to KNO scaling at LHC energies. The enlarged scaling function describes the observed violation of the KNO scaling.

    hep-phhep-exInt.J.Mod.Phys.A(2019)·9 citations
13. 13*

    Enhancing Sensitivity to Non-Standard Neutrino Interactions at INO combining muon and hadron information

    Amina Khatun🇮🇳 · Sabya Sachi Chatterjee🇬🇧 · Tarak Thakore🇺🇸 · Sanjib Kumar Agarwalla🇮🇳

    The neutral current non-standard interactions (NSI's) of neutrino with matter fermions while propagating through long distances inside the Earth matter can give rise to the extra matter potentials apart from the standard MSW potential due to the $W$-mediated interactions in matter. In this paper, we explore the impact of flavor violating neutral current NSI parameter ${\epsilon }_{\mu \tau }$ in the oscillation of atmospheric neutrino and antineutrino using the 50 kt magnetized ICAL detector at INO. We find that due to non-zero ${\epsilon }_{\mu \tau }$, ${\nu }_{\mu }\to {\nu }_{\mu }$ and ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_{\mu }$ transition probabilities get modified substantially at higher energies and longer baselines, where vacuum oscillation dominates. We estimate the sensitivity of the ICAL detector for various choices of binning schemes and observables. The most optimistic bound on ${\epsilon }_{\mu \tau }$ that we obtain is $-0.01<{\epsilon }_{\mu \tau }<0.01$ at 90$\%$ C.L. using 500 kt$\cdot$yr exposure and considering $E_{\mu },\cos {\theta }_{\mu },E_{\mathrm{had}}^{\prime }$ as observables in their ranges [1, 21] GeV, [-1, 1], and [0, 25] GeV respectively. For the first time we show that the charge identification capability of the ICAL detector is crucial to set stringent constraints on ${\epsilon }_{\mu \tau }$. We also show that when we marginalize over ${\epsilon }_{\mu \tau }$ in fit in its range of -0.1 to 0.1, the mass hierarchy sensitivity deteriorates by 10$\%$ to 20$\%$ depending on the analysis mode, and the precision measurements of atmospheric parameters remain quite robust at the ICAL detector.

    hep-phhep-exphysics.ins-detEPJC(2020)·20 citations
14. 14*

    Towards a W boson mass measurement with LHCb

    Martina Pili (on behalf of the LHCb Collaboration)🇬🇧

    LHCb provides unique opportunities to study $W$ and $Z$ boson production at forward rapidities at the LHC. It has recently been suggested that a measurement of the $W$ boson mass by LHCb would complement measurements by ATLAS and CMS. All measurements of the $W$ mass at hadron colliders are subject to PDF uncertainties, but there would be a partial cancellation of the overall PDF uncertainty when the LHCb result is included in an average with measurements by ATLAS and CMS. Here we review measurements of $W$ and $Z$ boson production by LHCb, and report on a new study of the PDF uncertainty on the LHCb measurement of the $W$ mass. The latter study includes the proposal of a new approach that should reduce the PDF uncertainty by roughly a factor of two with LHCb Run 2 data.

    hep-phhep-exPoS(2019)·1 citation
15. 15*

    Determining the Shape of Higgs Potential at Future Colliders

    Pankaj Agrawal🇮🇳 · Debashis Saha🇮🇳 · Ling-Xiao Xu🇨🇳 · Jiang-Hao Yu🇨🇳 · C.-P. Yuan🇺🇸

    Although the Higgs boson has been discovered, its self-couplings are poorly constrained. This leaves the nature of the Higgs boson undetermined. Motivated by different Higgs potential scenarios other than the Landau-Ginzburg type in the standard model, we systematically organize various new physics scenarios -- elementary Higgs, Nambu-Goldstone Higgs, Coleman-Weinberg Higgs, and Tadpole-induced Higgs, etc. We find that double-Higgs production at the 27 TeV high energy LHC can be used to discriminate different Higgs potential scenarios, while it is necessary to use triple-Higgs production at a future 100 TeV proton-proton collider to fully determine the shape of the Higgs potential.

    hep-phhep-exPRD(2020)·60 citations
16. 16*

    High energy QCD Lipatov's effective action in Euclidean space

    S.Bondarenko🇮🇱

    The continuation of high energy QCD Lipatov's effective action to Euclidean space is performed. The resulting Euclidean QCD RFT action is considered separately in Euclidean "light-cone" coordinates and axial gauge suitable for the numerical and analytical calculations correspondingly. The further application of the obtained results is also discussed.

    ↳ hep-thhep-phEPJC(2020)·2 citations
17. 17*

    A preliminary forecast for cosmological parameter estimation with gravitational-wave standard sirens from TianQin

    Ling-Feng Wang🇨🇳 · Ze-Wei Zhao🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    TianQin is a space-based gravitational-wave observatory scheduled to be launched in the 2030s. In this work, we make a preliminary forecast for the cosmological parameter estimation with the gravitational-wave standard siren observation from TianQin. We simulate the standard siren data of TianQin based on its 5-year observation after the completion of construction. In the simulation, three models for the population of massive black hole binary (MBHB), i.e., pop III, Q3nod, and Q3d, are considered to predict the event numbers of MBHB mergers. We find that: (i) among the three MBHB models, the Q3nod model can provide the tightest constraints on the cosmological parameters; (ii) TianQin's standard siren observation can effectively break the parameter degeneracies inherent in the cosmic microwave background observation; and (iii) the future standard siren observation from TianQin can significantly improve the cosmological parameter estimation under the current mainstream electromagnetic observations.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·67 citations
18. 18*

    Anisotropic string tensions and inversely magnetic catalyzed deconfinement from a dynamical AdS/QCD model

    Hardik Bohra🇮🇳 · David Dudal🇧🇪 · Ali Hajilou🇧🇪 · Subhash Mahapatra🇮🇳

    We extend previous work on dynamical AdS/QCD models by introducing an extra ingredient under the form of a background magnetic field, this to gain insight into the influence such field can have on crucial QCD observables. Therefore, we construct a closed form analytic solution to an Einstein-Maxwell-dilaton system with a magnetic field. We specifically focus on the deconfinement transition, reporting inverse magnetic catalysis, and on the string tension, reporting a weaker/stronger confinement along/perpendicular to the magnetic field. The latter, being of importance to potential modelling of heavy quarkonia, is in qualitative agreement with lattice findings.

    ↳ hep-thgr-qchep-lathep-phPLB(2020)·108 citations
19. 19*

    Interplay between $SU(N_f)$ chiral symmetry, $U(1{)}_A$ axial anomaly and massless bosons

    Vicente Azcoiti🇪🇸

    The standard wisdom on the origin of massless bosons in the spectrum of a Quantum Field Theory $(QFT)$ describing the interaction of gauge fields coupled to matter fields is based on two well known features: gauge symmetry, and spontaneous symmetry breaking of continuous global symmetries. However we will show in this article how the topological properties, that originate the $U(1{)}_A$ axial anomaly in a $QFT$ which describes the interaction of fermion matter fields and gauge bosons, are the basis of an alternative mechanism to generate massless bosons in the chiral limit, if the non-abelian $SU(N_f{)}_A$ chiral symmetry is fulfilled in the vacuum. We will also test our predictions with the results of a well known two-dimensional model, the two-flavour Schwinger model, which was analyzed by Coleman long ago, and will give a reliable answer to some of the questions he asked himself on the spectrum of the model in the strong-coupling (chiral) limit. We will also analyze what are the expectations for the $U(N)$ gauge-fermion model in two dimensions, and will discuss on the impact of our results in the chirally symmetric high temperature phase of $QCD$, which was present in the early universe, and is expected to be created in heavy-ion collision experiments.

    ↳ hep-lathep-phhep-thPRD(2019)·7 citations
20. 20*

    Vector Space of Feynman Integrals and Multivariate Intersection Numbers

    Hjalte Frellesvig🇮🇹 · Federico Gasparotto🇮🇹 · Manoj K. Mandal🇮🇹 · Pierpaolo Mastrolia🇮🇹 · Luca Mattiazzi🇮🇹 · Sebastian Mizera🇨🇦

    Feynman integrals obey linear relations governed by intersection numbers, which act as scalar products between vector spaces. We present a general algorithm for constructing multivariate intersection numbers relevant to Feynman integrals, and show for the first time how they can be used to solve the problem of integral reduction to a basis of master integrals by projections, and to directly derive functional equations fulfilled by the latter. We apply it to the derivation of contiguity relations for special functions admitting multi-fold integral representations, and to the decomposition of a few Feynman integrals at one- and two-loops, as first steps towards potential applications to generic multi-loop integrals.

    ↳ hep-thhep-phPRL(2019)·213 citations
21. 21*

    Orbital Inflation: inflating along an angular isometry of field space

    Ana Achucarro🇳🇱 · Yvette Welling🇩🇪

    The simplicity of the CMB data, so well described by single-field inflation, raises the question whether there might be an equally simple multi-field realization consistent with the observations. We explore the idea that an approximate 'angular' shift symmetry in field space (an isometry) protects the dynamics of coupled inflationary perturbations. This idea relates to the recent observation that multi-field inflation mimics the predictions of single-field inflation, if the inflaton is efficiently and constantly coupled to a second massless degree of freedom (the isocurvature perturbation). In multi-field inflation, the inflationary trajectory is in general not aligned with the gradient of the potential. As a corollary the potential does not reflect the symmetries of perturbations. We propose a new method to reconstruct simultaneously a two-field action and an inflationary trajectory which proceeds along an `angular' direction of field space, with a constant radius of curvature, and that has a controlled mass of `radial' isocurvature perturbations (entropy mass). We dub this `Orbital Inflation'. In this set-up the Hubble parameter determines the behavior of both the background and the perturbations. First, Orbital Inflation provides a playground for quasi-single field inflation. Second, the exquisite analytical control of these models allows us to exactly solve the phenomenology of Orbital Inflation with a small entropy mass and a small radius of curvature, a regime not previously explored. The predictions are single-field-like, although the consistency relations are violated. Moreover, the value of the entropy mass dictates how the inflationary predictions fan out in the ($n_s$, $r$) plane. Depending on the size of the self interactions of the isocurvature perturbations, the non-Gaussianity parameter $f_{NL}$ can range from slow-roll suppressed to $\mathcal{O}(\text{a few})$.

    ↳ hep-thastro-ph.COgr-qchep-ph32 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.