Mon·Apr 9, 2018Monday·April 9, 2018

1. 01*

   Lepton nonuniversality anomalies and implications

   Gudrun Hiller🇩🇪

   We discuss avenues for diagnosing new physics hinted from lepton nonuniversality in rare $b$-decays, and physics implications.

   hep-phhep-ex10 citations
2. 02*

   The 1-loop effective potential for the Standard Model in curved spacetime

   Tommi Markkanen🇬🇧 · Sami Nurmi🇫🇮 · Arttu Rajantie🇬🇧 · Stephen Stopyra🇬🇧

   The renormalisation group improved Standard Model effective potential in an arbitrary curved spacetime is computed to one loop order in perturbation theory. The loop corrections are computed in the ultraviolet limit, which makes them independent of the choice of the vacuum state and allows the derivation of the complete set of $\beta$-functions. The potential depends on the spacetime curvature through the direct non-minimal Higgs-curvature coupling, curvature contributions to the loop diagrams, and through the curvature dependence of the renormalisation scale. Together, these lead to significant curvature dependence, which needs to be taken into account in cosmological applications, which is demonstrated with the example of vacuum stability in de Sitter space.

   hep-phgr-qchep-thJHEP(2018)·96 citations
3. 03*

   Exploring Partial $\mu$-$\tau$ Reflection Symmetry at DUNE and Hyper-Kamiokande

   Kaustav Chakraborty🇮🇳 · K.N. Deepthi🇮🇳 · Srubabati Goswami🇮🇳 · Anjan S. Joshipura🇮🇳 · Newton Nath🇨🇳

   We study origin, consequences and testability of a hypothesis of `partial $\mu$-$\tau$' reflection symmetry. This symmetry predicts $|U_{\mu i}|=|U_{\tau i}|(i=1,2,3)$ for a single column of the leptonic mixing matrix $U$. Depending on whether this symmetry holds for the first or second column of $U$ different correlations between ${\theta }_{23}$ and ${\delta }_{CP}$ can be obtained. This symmetry can be obtained using discrete flavour symmetries. In particular, all the subgroups of SU(3) with 3-dimensional irreducible representation which are classified as class C or D can lead to partial $\mu$-$\tau$ reflection symmetry. We show how the predictions of this symmetry compare with the allowed area in the ${\sin }^2{\theta }_{23}-{\delta }_{CP}$ plane as obtained from the global analysis of neutrino oscillation data. Furthermore, we study the possibility of testing these symmetries at the proposed DUNE and Hyper-Kamiokande (HK) experiments (T2HK, T2HKK), by incorporating the correlations between ${\theta }_{23}$ and ${\delta }_{CP}$ predicted by the symmetries. We find that when simulated data of DUNE and HK is fitted with the symmetry predictions, the ${\theta }_{23}-{\delta }_{CP}$ parameter space gets largely restricted near the CP conserving values of ${\delta }_{CP}$. Finally, we illustrate the capability of these experiments to distinguish between the two cases leading to partial $\mu -\tau$ symmetry namely $|U_{\mu 1}|=|U_{\tau 1}|$ and $|U_{\mu 2}|=|U_{\tau 2}|$.

   hep-phPRD(2018)·22 citations
4. 04*

   A simplified expression for the one-loop soft-gluon current with massive fermions

   Michal Czakon🇩🇪 · Alexander Mitov🇬🇧

   We present a much simpler analytic expression for the UV un-renormalized one-loop soft-gluon current which controls the infra-red behavior of one-loop QCD amplitudes with massive fermions when an external gluon becomes soft. The result is given entirely in terms of standard polylogarithms, is of uniform transcendentality and is well-suited for computer implementation.

   hep-phhep-th17 citations
5. 05*

   Revised Criteria for Stability in the General Two-Higgs Doublet Model

   Yithsbey Giraldo🇨🇴 · Larry Burbano🇨🇴

   We will revise one of the methods given in the literature to determine the necessary and sufficient conditions that the parameters must satisfy to have a stable scalar potential in the general two-Higgs doublet model. We will give a procedure that facilitates finding the conditions for stability of a scalar potential. The stability guarantees that the scalar potential has a global minimum, that is, the potential is bounded from below, which is a necessary condition to implement the spontaneous gauge-symmetry breaking in the models.

   hep-ph0 citations
6. 06*

   Revisiting the direct detection of dark matter in simplified models

   Tong Li🇦🇺

   In this work we numerically re-examine the loop-induced WIMP-nucleon scattering cross section for the simplified dark matter models and the constraint set by the latest direct detection experiment. We consider a fermion, scalar or vector dark matter component from five simplified models with leptophobic spin-0 mediators coupled only to Standard Model quarks and dark matter particles. The tree-level WIMP-nucleon cross sections in these models are all momentum-suppressed. We calculate the non-suppressed spin-independent WIMP-nucleon cross sections from loop diagrams and investigate the constrained space of dark matter mass and mediator mass by Xenon1T. The constraints from indirect detection and collider search are also discussed.

   hep-phPLB(2018)·28 citations
7. 07*

   Effect of final state interactions on neutrino energy reconstruction at DUNE

   Sabeeha Naaz🇮🇳 · Anupam Yadav🇮🇳 · Jyotsna Singh🇮🇳 · R. B. Singh🇮🇳

   We quantitatively study the percentage of fake events present in CCQE and CCRes interactions and the impact of final state interactions on the neutrino oscillation parameters at Dune. Resonance interaction will be the most dominant interaction in the oscillation sensitive region of DUNE. The effect of final-state interactions for DUNE oscillation physics is analysed in an ideal and realistic detector scenario. The ${\nu }_{\mu }$-disappearance Oscillation channel is studied using LAr detector. We find that nuclear effects and detector thresholds plays an significant role in CCQE and CCRes interactions and these nuclear effects induces a significant bias in the determination of atmospheric oscillation parameters. The impression of nuclear effects on the determination of ${\theta }_{23}$ is quantified in this work.

   hep-phNPB(2018)·14 citations
8. 08*

   The Two-mass Contribution to the Three-Loop Gluonic Operator Matrix Element $A_{gg,Q}^{(3)}$

   J. Ablinger🇦🇹 · J. Blümlein🇩🇪 · A. De Freitas🇩🇪 · A. Goedicke🇩🇪 · C. Schneider🇦🇹 · K. Schönwald🇩🇪

   We calculate the two-mass QCD contributions to the massive operator matrix element $A_{gg,Q}$ at $\mathcal{O}({\alpha }_s^3)$ in analytic form in Mellin $N$- and $z$-space, maintaining the complete dependence on the heavy quark mass ratio. These terms are important ingredients for the matching relations of the variable flavor number scheme in the presence of two heavy quark flavors, such as charm and bottom. In Mellin $N$-space the result is given in the form of nested harmonic, generalized harmonic, cyclotomic and binomial sums, with arguments depending on the mass ratio. The Mellin inversion of these quantities to $z$-space gives rise to generalized iterated integrals with square root valued letters in the alphabet, depending on the mass ratio as well. Numerical results are presented.

   hep-phhep-exhep-thNPB(2018)·43 citations
9. 09*

   Exploiting the WH/ZH symmetry in the search for New Physics

   R.V. Harlander🇩🇪 · J. Klappert🇩🇪 · C. Pandini🇨🇭 · A. Papaefstathiou🇳🇱

   We suggest to isolate the loop-induced gluon-initiated component ($gg\to ZH$) for associated $ZH$ production by using the similarity of the Drell-Yan-like component for $ZH$ production to the $WH$ process. We argue that the cross-section ratio of the latter two processes can be predicted with high theoretical accuracy. Comparing it to the experimental $ZH/WH$ cross-section ratio should allow to probe for New Physics in the $gg\to ZH$ component at the HL-LHC. We consider typical BSM scenarios in order to exemplify the effect they would have on the proposed observable.

   hep-phEPJC(2018)·24 citations
10. 10*

    ${\eta }_c$ photoproduction at LHC energies

    V. P. Goncalves🇧🇷 · B. D. Moreira🇧🇷

    In this contribution, we study the inclusive and diffractive ${\eta }_c$ photoproduction in $pp$ and $pPb$ ultra-peripheral collisions (UPC's) at the LHC Run 2 energies. The quarkonium production is studied using nonrelativistic quantum chromodynamics (NRQCD) formalism. We present predictions for rapidity and transverse momentum distributions for the ${\eta }_c$ photoproduction and present our estimate for the total cross sections at the Run 2 energies.

    hep-phhep-ex0 citations
11. 11*

    Bound on a diffuse flux of ultra-high energy neutrinos in the ADD model

    M.O. Astashenkov🇷🇺 · A.V. Kisselev🇷🇺

    The search for ultra-high energy downward-going and Earth-skimming cosmic neutrinos by the Surface Detector array of the Pierre Auger Observatory (PAO) is analyzed in the ADD model with n extra flat spatial dimensions. We assumed that the diffuse neutrino flux dN_nu/dE_nu$ is equal to k E_nu^(-20) in the energy range 10^(17) eV - 2.5 10^(19) eV. Taking into account that no neutrino events where found by the PAO, we have estimated an upper bound on a value of k. It is shown that this bound can be stronger than the upper bound on k recently obtained by the Pierre Auger Collaboration, depending on n and (n+4)-dimensional gravity scale M_D.

    hep-phastro-ph.HEPRD(2018)·1 citation
12. 12*

    Next-to-minimal dark matter at the LHC

    Aoife Bharucha🇫🇷 · Felix Brümmer🇫🇷 · Nishita Desai🇫🇷

    We examine the collider signatures of a WIMP dark matter scenario comprising a singlet fermion and an SU(2) n-plet fermion, with a focus on n=3 and n=5. The singlet and n-plet masses are of the order of the electroweak scale. The n-plet contains new charged particles which will be copiously pair-produced at the LHC. Small mixing angles and near-degenerate masses, both of which feature naturally in these models, give rise to long-lived particles and their characteristic collider signatures. In particular, the n=5 model can be constrained by displaced lepton searches independently of the mixing angle, generically ruling out 5-plet masses below about 280 GeV. For small mixing angles, we show that there is a parameter range for which the model reproduces the observed thermal relic density but is severely constrained by disappearing track searches in both the n=3 and the n=5 cases. The n=3 model is further constrained by soft di-lepton searches irrespectively of whether any new particles are long-lived.

    hep-phJHEP(2018)·21 citations
13. 13*

    Model-independent bounds probing on the electromagnetic dipole moments of the $\tau$-lepton at the CLIC

    M. Koksal🇹🇷 · A. A. Billur🇹🇷 · A. Gutierrez-Rodriguez🇲🇽 · M. A. Hernandez-Ruiz🇲🇽

    We establish model independent bounds on the anomalous magnetic and electric dipole moments of the tau-lepton using the two-photon processes $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ and $\gamma \gamma \to {\tau }^{+}{\tau }^{-}\gamma$. We use $\mathcal{L}=10,50,100,300,500,1000,1500,2000,3000f{b}^{-1}$ of data collected with the future $e^{+}{e}^{-}$ linear collider such as the CLIC at $\sqrt{s}=380,1500,3000GeV$ and we consider systematic uncertainties of ${\delta }_{sys}=0,3,5\%$. Precise bounds at $95\%$ C. L. on the anomalous dipole moments to the tau-lepton $-0.00015\le {\tilde{a}}_{\tau }\le 0.00017$ and $|{\tilde{d}}_{\tau }(ecm)|=9.040\times 10^{-19}$ are set from our study. Our results show that the processes under consideration are a very good prospect for probing the dipole moments of the tau-lepton at the future $e^{+}{e}^{-}$ linear collider at the $\gamma \gamma$ mode.

    hep-phPRD(2018)·30 citations
14. 14*

    Surprising phenomenology in the non-Universal U(1) gauge extended $\mu \nu$SSM

    Victor Martin Lozano🇩🇪 · Santiago Oviedo Casado🇪🇸

    So far the most sophisticated experiments have shown no trace of new physics at the TeV scale. Consequently, new models with unexplored parameter regions are necessary to explain current results, re-examine the existing data, and propose new experiments. In this Letter, we present a modified version of the $\mu \nu$SSM supersymmetric model where a non-Universal extra U(1) gauge symmetry is added in order to restore an effective R-parity that ensures proton stability. We show that anomalies equations cancel without having to add \emph{any} exotic matter, restricting the charges of the fields under the extra symmetry to a discrete set of values. We find that it is the viability of the model through anomalies cancellation what defines the conditions in which fermions interact with dark matter candidates via the exchange of $Z^{\prime }$ bosons. The strict condition of universality violation means that LHC constraints for a $Z^{\prime }$ mass do not apply directly to our model, allowing for a yet undiscovered relatively light $Z$', as we discuss both in the phenomenological context and in its implications for possible flavour changing neutral currents. Moreover, we explore the possibility of isospin violating dark matter interactions; we observe that this interaction depends, surprisingly, on the Higgs charges under the new symmetry, both limiting the number of possible models and allowing to analyse indirect dark matter searches in the light of well defined, particular scenarios.

    hep-phJHEP(2018)·7 citations
15. 15*

    A universally enhanced light-quarks Yukawa couplings paradigm

    Shaouly Bar-Shalom🇮🇱 · Amarjit Soni🇺🇸

    We propose that natural TeV-scale new physics (NP) with $\mathcal{O}(1)$ couplings to the standard model (SM) quarks may lead to a universal enhancement of the Yukawa couplings of all the light quarks, perhaps to a size comparable to that of the SM b-quark Yukawa coupling, i.e., $y_q\sim \mathcal{O}(y_b^{SM})$ for $q=u,d,c,s$. This scenario is described within an effective field theory (EFT) extension of the SM, for which a potential contribution of certain dimension six effective operators to the light quarks Yukawa couplings is $y_q\sim \mathcal{O}\left(f\frac{v^2}{{\Lambda }^2}\right)$, where $v$ is the Higgs vacuum expectation value (VEV), $v=246$ GeV, $\Lambda$ is the typical scale of the underlying heavy NP and $f$ is the corresponding Wilson coefficient which depends on its properties and details. In particular, we study the case of $y_q\sim 0.025\sim y_b^{SM}$, which is the typical size of the enhanced light-quark Yukawa couplings if the NP scale is around $\Lambda \sim 1.5$ TeV and the NP couplings are natural, i.e., $f\sim \mathcal{O}(1)$. We also explore this enhanced light quarks Yukawa paradigm in extensions of the SM which contain TeV-scale vector-like quarks and we match them to the specific higher dimensional effective operators in the EFT description. We discuss the constraints on this scenario and the flavor structure of the underlying NP dynamics and suggest some resulting "smoking gun" signals that should be searched for at the LHC, such as multi-Higgs production $pp\to hh,hhh$ and single Higgs production in association with a high $p_T$ jet ($j$) or photon $pp\to hj,h\gamma$ and with a single top-quark $pp\to ht$.

    hep-phhep-exPRD(2018)·38 citations
16. 16*

    Dual QCD Insight into BSM Hadronic Matrix Elements for $K^0-{\bar{K}}^0$ Mixing from Lattice QCD

    Andrzej J. Buras🇩🇪 · Jean-Marc Gerard🇧🇪

    We calculate BSM hadronic matrix elements for $K^0-{\bar{K}}^0$ mixing in the Dual QCD approach (DQCD). The ETM, SWME and RBC-UKQCD lattice collaborations find the matrix elements of the BSM density-density operators ${\mathcal{O}}_i$ with $i=2-5$ to be rather different from their vacuum insertion values (VIA) with $B_2\approx 0.5$, $B_3\approx B_5\approx 0.7$ and $B_4\approx 0.9$ at $\mu =3GeV$ to be compared with $B_i=1$ in the VIA. We demonstrate that this pattern can be reconstructed within the DQCD through the non-perturbative meson evolution from very low scales, where factorization of matrix elements is valid, to scales of order $(1GeV)$ with subsequent perturbative quark-gluon evolution to $\mu =3GeV$. This turns out to be possible in spite of a very different pattern displayed at low scales with $B_2=1.2$, $B_3=3.0$, $B_4=1.0$ and $B_5\approx 0.2$ in the large $N$ limit, $N$ being the number of colours. Our results imply that the inclusion of meson evolution in the phenomenology of any non-leptonic transition like $K^0-{\bar{K}}^0$ mixing and $K\to \pi \pi$ decays is mandatory. While meson evolution, as demonstrated in our paper, is hidden in LQCD results, to our knowledge DQCD is the only analytic approach for non-leptonic transitions and decays which takes this important QCD dynamics into account.

    hep-phhep-exhep-latActa Phys.Polon.B(2019)·33 citations
17. 17*

    Gravitational Waves and Neutrinos

    Riccardo Sturani (IIP-UFRN, Natal)🇧🇷

    We give an overview about the recent detection of gravitational waves by the Advanced LIGO first and second observing runs and by Advanced Virgo, with emphasis on the prospects for multi-messenger astronomy involving neutrino detections.

    hep-phastro-ph.HE1 citation
18. 18*

    Towards Reliable Nuclear Matrix Elements for Neutrinoless $\beta \beta$ Decay

    Javier Menéndez🇯🇵

    The calculated nuclear matrix elements for the neutrinoless double-beta ($0\nu \beta \beta$) decay suffer from several limitations. Predicted matrix-element values depend on the many-body method used to calculate them and, in addition, they may need to be "quenched", albeit by an unknown amount due to the relatively high momentum transferred in the decay. These uncertainties are hard to figure out from theoretical calculations alone because of the unique character of $0\nu \beta \beta$ decay, not clearly related to other nuclear structure observables. We present recent progress in the determination of the nuclear matrix elements. First, we report improved shell model calculations in an extended configuration space of two harmonic oscillator shells. Second, we note the relation between the $0\nu \beta \beta$ decay and double Gamow-Teller transitions that can in principle be measured in double charge-exchange reactions. These new insights pave the way for a more reliable estimation of the value of the nuclear matrix elements.

    ↳ nucl-thhep-exhep-phnucl-exJPS Conf.Proc.(2018)·2 citations
19. 19*

    Neutrinoless $\beta \beta$ decay mediated by the exchange of light and heavy neutrinos: The role of nuclear structure correlations

    Javier Menéndez🇯🇵

    Neutrinoless $\beta \beta$ decay nuclear matrix elements calculated with the shell model and energy-density functional theory typically disagree by more than a factor of two in the standard scenario of light-neutrino exchange. In contrast, for a decay mediated by sterile heavy neutrinos the deviations are reduced to about 50\%, an uncertainty similar to the one due to short-range effects. We compare matrix elements in the light- and heavy-neutrino-exchange channels, exploring the radial, momentum transfer and angular momentum-parity matrix element distributions, and considering transitions that involve correlated and uncorrelated nuclear states. We argue that the shorter-range heavy-neutrino exchange is less sensitive to collective nuclear correlations, and that discrepancies in matrix elements are mostly due to the treatment of long-range correlations in many-body calculations. Our analysis supports previous studies suggesting that isoscalar pairing correlations, which affect mostly the longer-range part of the neutrinoless $\beta \beta$ decay operator, are partially responsible for the differences between nuclear matrix elements in the standard light-neutrino-exchange mechanism.

    ↳ nucl-thhep-exhep-phnucl-exJ.Phys.G(2018)·125 citations
20. 20*

    Temperature dependence of bulk viscosity within lattice simulation of $SU(3)$--gluodynamics

    N.Yu. Astrakhantsev🇷🇺 · V.V. Braguta🇷🇺 · A.Yu. Kotov🇷🇺

    In this paper the temperature dependence of the $SU(3)$--gluodynamics bulk viscosity is studied within lattice simulations. To carry out this study we measure the correlation function of the trace of the energy-momentum tensor for a set of temperatures within the range $T/T_c\in (0.9,1.5)$. To extract the bulk viscosity from the correlation function we apply the Backus-Gilbert method and the Tikhonov regularization method. We show that the ratio $\zeta /s$ is small in the region $T/T_c⩾1.1-1.2$ and in the vicinity of the transition $T/T_c⩽1.1-1.2$ it quickly rises. Our results are in agreement with previous lattice studies and in a reasonable agreement with other phenomenological approaches. Obtained values of the bulk viscosity are significantly larger than perturbative results, what confirms that QGP is a strongly correlated system.

    ↳ hep-lathep-phhep-thPRD(2018)·67 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.