Thu·May 26, 2016Thursday·May 26, 2016

1. 01*

   Large BR(h -> tau mu) in Supersymmetric Models

   Ahmed Hammad🇪🇬 · Shaaban Khalil🇪🇬 · Cem Salih Un🇹🇷

   We analyze the Lepton Flavor Violating (LFV) Higgs decay h -> tau mu in three supersymmetric models: Minimal Supersymmetric Standard Model (MSSM), Supersymmetric Seesaw Model (SSM), and Supersymmetric B-L model with Inverse Seesaw (BLSSM-IS). We show that in generic MSSM, with non-universal slepton masses and/or trilinear couplings, it is not possible to enhance BR(h -> tau mu) without violating the experimental bound on the BR(tau -> mu gamma). In SSM, where flavor mixing is radiatively generated, the LFV process mu -> e gamma strictly constrains the parameter space and the maximum value of BR(h -> tau mu) is of order 10^-10, which is extremely smaller than the recent results reported by the CMS and ATLAS experiments. In BLSSM-IS, with universal soft SUSY breaking terms at the grand unified scale, we emphasize that the measured values of BR(h -> tau mu) can be accommodated in a wide region of parameter space without violating LFV constraints. Thus, confirming the LFV Higgs decay results will be a clear signal of BLSSM-IS type of models. Finally, the signal of h -> tau mu in the BLSSM-IS at the LHC, which has a tiny background, is analyzed.

   hep-phPRD(2017)·23 citations
2. 02*

   Light Adjoint Quarks in the Instanton-Dyon Liquid Model IV

   Yizhuang Liu🇺🇸 · Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸

   We discuss the instanton-dyon liquid model with $N_f$ Majorana quark flavors in the adjoint representation of color $S{U}_c(2)$ at finite temperature. We briefly recall the index theorem on $S^1\times R^3$ for twisted adjoint fermions in a BPS dyon background of arbitrary holonomy, and use the ADHM construction to explicit the adjoint anti-periodic zero modes. We use these results to derive the partition function of an interacting instanton-dyon ensemble with $N_f$ light and anti-periodic adjoint quarks. We develop the model in details by mapping the theory on a 3-dimensional quantum effective theory with adjoint quarks with manifest $SU(N_f)\times Z_{4N_f}$ symmetry. Using a mean-field analysis at weak coupling and strong screening, we show that center symmetry requires the spontaneous breaking of chiral symmetry, which is shown to only take place for $N_f=1$. For a sufficiently dense liquid, we find that the ground state is center symmetric and breaks spontaneously flavor symmetry through $SU(N_f)\times Z_{4N_f}\to O(N_f)$. As the liquid dilutes with increasing temperature, center symmetry and chiral symmetry are restored. We present numerical and analytical estimates for the transition temperatures.

   hep-phhep-lathep-thPRD(2016)·14 citations
3. 03*

   Decay coupling constants sum rules for dibaryon octet into two baryon octets with ${\lambda }_8$ first order SU(3) symmetry breaking

   E. N. Polanco-Euán🇲🇽 · V. Gupta🇲🇽 · G. Sánchez-Colón🇲🇽 · B. A. Bambah🇮🇳

   The SU(3) octet states with baryon number B = 2, hexaquark dibaryons, are considered. Decay coupling constants sum rules for dibaryon octet into two ordinary baryon octets with ?${\lambda }_8$ first order SU(3) symmetry breaking are given. An SU(4) extension of the analysis is commented upon. Possibilities for the experimental observation of multibaryon and anti-multibaryon states are pointed out.

   hep-phJ.Phys.Conf.Ser.(2016)·2 citations
4. 04*

   The LPM effect in sequential bremsstrahlung 2: factorization

   Peter Arnold🇺🇸 · Han-Chih Chang🇺🇸 · Shahin Iqbal🇺🇸

   The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g.\ overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is the case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\hat{q}$ approximation; large $N_c$; and neglect for the moment of processes involving 4-gluon vertices) and explicitly compute the correction $\Delta d\Gamma /dxdy$ due to overlapping formation times.

   hep-phnucl-thJHEP(2016)·47 citations
5. 05*

   On the Standard Model predictions for $R_K$ and $R_{K^{\ast }}$

   Marzia Bordone🇨🇭 · Gino Isidori🇨🇭 · Andrea Pattori🇨🇭

   We evaluate the impact of radiative corrections in the ratios $\Gamma [B\to M{\mu }^{+}{\mu }^{-}]/\Gamma [B\to M{e}^{+}{e}^{-}]$ when the meson $M$ is a $K$ or a $K^{\ast }$. Employing the cuts on $m_{\ell \ell }^2$ and the reconstructed $B$-meson mass presently applied by the LHCb Collaboration, such corrections do not exceed a few $\%$. Moreover, their effect is well described (and corrected for) by existing Montecarlo codes. Our analysis reinforces the interest of these observables as clean probe of physics beyond the Standard Model.

   hep-phhep-exEPJC(2016)·598 citations
6. 06*

   Electron electric dipole moment in Inverse Seesaw models

   Asmaa Abada🇫🇷 · Takashi Toma🇫🇷

   We consider the contribution of sterile neutrinos to the electric dipole moment of charged leptons in the most minimal realisation of the Inverse Seesaw mechanism, in which the Standard Model is extended by two right-handed neutrinos and two sterile fermion states. Our study shows that the two pairs of (heavy) pseudo-Dirac mass eigenstates can give significant contributions to the electron electric dipole moment, lying close to future experimental sensitivity if their masses are above the electroweak scale. The major contribution comes from two-loop diagrams with pseudo-Dirac neutrino states running in the loops. In our analysis we further discuss the possibility of having a successful leptogenesis in this framework, compatible with a large electron electric dipole moment.

   hep-phhep-exJHEP(2016)·39 citations
7. 07*

   Diffractive $\rho$ and $\varphi$ production at HERA using an AdS/QCD holographic light-front meson wavefunction

   Mohammad Ahmady🇨🇦 · Ruben Sandapen🇨🇦 · Neetika Sharma🇮🇳

   We use an anti-de Sitter/Quantum Chromodynamics (AdS/QCD) holographic light-front wavefunction for the $\rho$ and $\varphi$ mesons, in conjunction with the Color Glass Condensate (CGC) dipole cross-section whose parameters are fitted to the most recent 2015 high precision HERA data on inclusive Deep Inelastic Scattering (DIS), in order to predict the cross-sections for diffractive $\rho$ and $\varphi$ electroproduction. Our results suggest that the holographic meson light-front wavefunction is able to give a simultaneous description of the $\rho$ and $\varphi$ production data provided we use a set of light quark masses with $m_{u,d}$ < $m_s$ ~ 0.14 GeV.

   hep-phPRD(2016)·53 citations
8. 08*

   Neutrino dynamics below the electroweak crossover

   J. Ghiglieri🇨🇭 · M. Laine🇨🇭

   We estimate the thermal masses and damping rates of active (m < eV) and sterile (M ~ GeV) neutrinos with thermal momenta k ~ 3T at temperatures below the electroweak crossover (5 GeV < T < 160 GeV). These quantities fix the equilibration or "washout" rates of Standard Model lepton number densities. Sterile neutrinos interact via direct scatterings mediated by Yukawa couplings, and via their overlap with active neutrinos. Including all leading-order reactions we find that the washout rate generally exceeds the Hubble rate for 5 GeV < T < 30 GeV. Therefore it is challenging to generate a large lepton asymmetry facilitating dark matter computations operating at T < 5 GeV, whereas the generation of a baryon asymmetry at T > 130 GeV remains an option. Our differential rates are tabulated in a form suitable for studies of specific scenarios with given neutrino Yukawa matrices.

   hep-phJCAP(2016)·78 citations
9. 09*

   Neutrino Mass Ordering in Future Neutrinoless Double Beta Decay Experiments

   Jue Zhang🇨🇳

   Motivated by recent intensive experimental efforts on searching for neutrinoless double beta decays, we present a detailed quantitative analysis on the prospect of resolving neutrino mass ordering in the next generation ${}^{76}$Ge-type experiments.

   hep-phMod.Phys.Lett.A(2016)·0 citations
10. 10*

    One-loop Chiral Perturbation Theory with two fermion representations

    Thomas DeGrand🇺🇸 · Maarten Golterman🇺🇸 · Ethan T. Neil🇺🇸 · Yigal Shamir🇮🇱

    We develop Chiral Perturbation Theory for chirally broken theories with fermions in two different representations of the gauge group. Any such theory has a non-anomalous singlet $U(1{)}_A$ symmetry, yielding an additional Nambu-Goldstone boson when spontaneously broken. We calculate the next-to-leading order corrections for the pseudoscalar masses and decay constants, which include the singlet Nambu-Goldstone boson, as well as for the two condensates. The results can be generalized to more than two representations.

    hep-phhep-latPRD(2016)·49 citations
11. 11*

    Tensor polarization dependent fragmentation functions and e+e-\to V \pi X at high energies

    Kai-bao Chen🇨🇳 · Wei-hua Yang🇨🇳 · Shu-yi Wei🇨🇳 · Zuo-tang Liang🇨🇳

    We present the systematic results for three dimensional fragmentation functions of spin one hadrons defined via quark-quark correlator. There are totally 72 such fragmentation functions, among them 18 are twist-2, 36 are twist-3 and 18 are twist-4. We also present the relationships between the twist-3 parts and those defined via quark-gluon-quark correlator obtained from the QCD equation of motion. We show that two particle semi-inclusive hadron production process $e^{+}{e}^{-}\to V\pi X$ at high energies is one of the best places to study the three-dimensional tensor polarization dependent fragmentation functions. We present the general kinematic analysis of this process and show that the cross section should be expressed in terms of 81 independent structure functions. After that we present parton model results for the hadronic tensor, the structure functions, the azimuthal and spin asymmetries in terms of these gauge invariant fragmentation functions at the leading order pQCD up to twist-3.

    hep-phPRD(2016)·47 citations
12. 12*

    Getting the Most from Detection of Galactic Supernova Neutrinos in Future Large Liquid-Scintillator Detectors

    Jia-Shu Lu🇨🇳 · Yu-Feng Li🇨🇳 · Shun Zhou🇨🇳

    Future large liquid-scintillator detectors can be implemented to observe neutrinos from a core-collapse supernova (SN) in our galaxy in various reaction channels: (1) The inverse beta decay ${\overline{\nu }}_e^{}+p\to n+e^{+}$; (2) The elastic neutrino-proton scattering $\nu +p\to \nu +p$; (3) The elastic neutrino-electron scattering $\nu +e^{-}\to \nu +e^{-}$; (4) The charged-current ${\nu }_e^{}$ interaction ${\nu }_e^{}+{}^{12}\mathrm{C}\to e^{-}+{}^{12}\mathrm{N}$; (5) The charged-current ${\overline{\nu }}_e^{}$ interaction ${\overline{\nu }}_e^{}+{}^{12}\mathrm{C}\to e^{+}+{}^{12}\mathrm{B}$; (6) The neutral-current interaction $\nu +{}^{12}\mathrm{C}\to \nu +{}^{12}{\mathrm{C}}^{\ast }$. The less abundant ${}^{13}\mathrm{C}$ atoms in the liquid scintillator are also considered as a target, and both the charged-current interaction ${\nu }_e^{}+{}^{13}\mathrm{C}\to e^{-}+{}^{13}\mathrm{N}$ and the neutral-current interaction $\nu +{}^{13}\mathrm{C}\to \nu +{}^{13}{\mathrm{C}}^{\ast }$ are taken into account. In this work, we show for the first time that a global analysis of all these channels at a single {liquid-}scintillator detector, such as Jiangmen Underground Neutrino Observatory (JUNO), is very important to test the average-energy hierarchy of SN neutrinos and how the total energy is partitioned among neutrino flavors. In addition, the dominant channels for reconstructing neutrino spectra and the impact of other channels are discussed in great detail.

    hep-phPRD(2016)·69 citations
13. 13*

    The electroweak theory based on SU(4)_L X U(1)_X gauge group

    H. N. Long🇻🇳 · L. T. Hue🇻🇳 · D. V. Loi🇻🇳

    This paper includes two main parts. In the first part, we present generalized gauge models based on SU(3)_C x SU(4)_L x U(1)_X (3-4-1) gauge group with arbitrary electric charge of leptons. The mixing matrix of neutral gauge bosons is analysed, the eigenmasses and eigenstates are obtained. The anomaly free as well as matching conditions are discussed precisely. In the second part, we present new development of the original 3-4-1 model [1,2]. In difference from previous works, in this paper the neutrinos, with the help of the decuplet H, get the Dirac masses at the tree level. The VEV of the Higgs field in the decuplet H acquiring VEV responsible for neutrino Dirac mass leads to mixing in separated pairs of singly charged gauge bosons, namely the SM W boson and K - new gauge boson acting in right-handed lepton sector, and the singly charged bileptons X and Y. Due to the mixing, there occurs a right-handed current carried by the SM W bosons. From the expression of the electromagnetic coupling constant, ones get the limit of square sinus of the Weinberg angle: sin^2 \theta_W < 0.25 and a constraint on electric charges of extra leptons. In the limit of lepton number conservation, the Higgs sector contains all massless Goldstone bosons for massive gauge bosons and the SM-like Higgs. Some phenomenology are pointed out.

    hep-phPRD(2016)·29 citations
14. 14*

    Parton Shower Matching Systematics in Vector-Boson-Fusion WW Production

    Michael Rauch🇩🇪 · Simon Plätzer🇬🇧

    We perform a detailed analysis of next-to-leading order plus parton-shower matching in vector-boson-fusion WW production including leptonic decays. The study is performed in the Herwig 7 framework interfaced to VBFNLO 3, using the angular-ordered and dipole-based parton-shower algorithms combined with the subtractive and multiplicative matching algorithms.

    hep-phEPJC(2017)·31 citations
15. 15*

    Theoretical determination of the hadronic (g-2) of the muon

    C. A. Dominguez🇿🇦 · K. Schilcher🇿🇦 · H. Spiesberger🇩🇪

    An approach is discussed on the determination of the leading order hadronic contribution to the muon anomaly, $a_{\mu }^{HAD}$, based entirely on theory. This method makes no use of $e^{+}{e}^{-}$ annihilation data, a likely source of the current discrepancy between theory and experiment beyond the $3\sigma$ level. What this method requires is essentially knowledge of the first derivative of the vector current correlator at zero-momentum. In the heavy-quark sector this is obtained from the well known heavy quark expansion in perturbative QCD, leading to values of $a_{\mu }^{HAD}$ in the charm- and bottom-quark region which were fully confirmed by later lattice QCD (LQCD) results. In the light-quark sector, using recent preliminary LQCD results for the first derivative of the vector current correlator at zero-momentum leads to the value $a_{\mu }^{HAD}=(729-871)\times 10^{-10}$, which is significantly larger than values obtained from using $e^{+}{e}^{-}$ data. A separate approach based on the operator product expansion (OPE), and designed to quench the contribution of these data, reduces the discrepancy by at least 40\%. In addition, it exposes a tension between the OPE and $e^{+}{e}^{-}$ data, thus suggesting the blame for the discrepancy on the latter.

    hep-phMod.Phys.Lett.A(2016)·5 citations
16. 16*

    Asymmetries in Heavy Quark Pair and Dijet Production at an EIC

    Daniël Boer🇳🇱 · Piet J. Mulders🇳🇱 · Cristian Pisano🇮🇹 · Jian Zhou🇨🇳

    Asymmetries in heavy quark pair and dijet production in electron-proton collisions allow studies of gluon TMDs in close analogy to studies of quark TMDs in semi-inclusive DIS. Here we present expressions for azimuthal asymmetries for both unpolarized and transversely polarized proton cases and consider the maximal asymmetries allowed. The latter are found to be rather sizeable, except in certain kinematic limits which are pointed out. In addition, we consider the small-x limit and expectations from a McLerran-Venugopalan model for unpolarized and linearly polarized gluons and from a perturbative, large transverse momentum calculation for the T-odd gluon TMDs. Comparison to related observables at RHIC and LHC is expected to provide valuable information about the process dependence of the gluon TMDs. In particular this will offer the possibility of a sign change test of the gluon Sivers TMD and two other T-odd gluon TMDs. This provides additional motivation for studies of azimuthal asymmetries in heavy quark pair and dijet production at a future Electron-Ion Collider.

    hep-phJHEP(2016)·111 citations
17. 17*

    Constraints on Z' models from LHC dijet searches and implications for dark matter

    Malcolm Fairbairn🇬🇧 · John Heal🇬🇧 · Felix Kahlhoefer🇩🇪 · Patrick Tunney🇬🇧

    We analyse a combination of ATLAS and CMS searches for dijet resonances at run I and run II, presenting the results in a way that can be easily applied to a generic Z' model. As an illustrative example, we consider a simple model of a Z' coupling to quarks and dark matter. We first study a benchmark case with fixed couplings and then focus on the assumption that the Z' is responsible for setting the dark matter relic abundance. Dijet constraints place significant bounds on this scenario, allowing us to narrow down the allowed range of dark matter masses for given Z' mass and width.

    hep-phhep-exJHEP(2016)·65 citations
18. 18*

    Hidden flavor symmetries of SO(10) GUT

    Borut Bajc🇸🇮 · Alexei Yu. Smirnov🇩🇪

    The Yukawa interactions of the SO(10) GUT with fermions in 16-plets (as well as with singlets) have certain intrinsic ("built-in") symmetries which do not depend on the model parameters. Thus, the symmetric Yukawa interactions of the 10 and 126 dimensional Higgses have intrinsic discrete $Z_2\times Z_2$ symmetries, while the antisymmetric Yukawa interactions of the 120 dimensional Higgs have a continuous SU(2) symmetry. The couplings of SO(10) singlet fermions with fermionic 16-plets have $U(1{)}^3$ symmetry. We consider a possibility that some elements of these intrinsic symmetries are the residual symmetries, which originate from the (spontaneous) breaking of a larger symmetry group $G_f$. Such an embedding leads to the determination of certain elements of the relative mixing matrix $U$ between the matrices of Yukawa couplings $Y_{10}$, $Y_{126}$, $Y_{120}$, and consequently, to restrictions of masses and mixings of quarks and leptons. We explore the consequences of such embedding using the symmetry group conditions. We show how unitarity emerges from group properties and obtain the conditions it imposes on the parameters of embedding. We find that in some cases the predicted values of elements of $U$ are compatible with the existing data fits. In the supersymmetric version of SO(10) such results are renormalization group invariant.

    hep-phNPB(2016)·14 citations
19. 19*

    Cornering diphoton resonance models at the LHC

    Mihailo Backović🇧🇪 · Suchita Kulkarni🇦🇹 · Alberto Mariotti🇧🇪 · Enrico Maria Sessolo🇵🇱 · Michael Spannowsky🇬🇧

    We explore the ability of the high luminosity LHC to test models which can explain the 750 GeV diphoton excess. We focus on a wide class of models where a 750 GeV singlet scalar couples to Standard Model gauge bosons and quarks, as well as dark matter. Including both gluon and photon fusion production mechanisms, we show that LHC searches in channels correlated with the diphoton signal will be able to probe wide classes of diphoton models with $\mathcal{L}\sim 3000{\text{fb}}^{-1}$ of data. Furthermore, models in which the scalar is a portal to the dark sector can be cornered with as little as $\mathcal{L}\sim 30{\text{fb}}^{-1}$.

    hep-phhep-exJHEP(2016)·4 citations
20. 20*

    Exotic Discoveries in Familiar Places: Theory of the Onia and Exotics

    Richard F. Lebed🇺🇸

    This brief overview presents an introduction to the heavy-quark exotic hadron candidates, $X$, $Y$, $Z$, $P_c$, believed to be tetraquark and pentaquark states. After an abridged account of their discovery, we outline the various theoretical pictures employed to describe their structure, with special focus on the new dynamical diquark picture.

    hep-phnucl-thPoS(2016)·3 citations
21. 21*

    First axion bounds from a pulsating helium-rich white dwarf star

    Tiara Battich🇦🇷 · Alejandro Hugo Córsico🇦🇷 · Leandro Gabriel Althaus🇦🇷 · Marcelo Miguel Miller Bertolami🇦🇷

    The Peccei-Quinn mechanism proposed to solve the CP problem of Quantum Chromodynamics has as consequence the existence of axions, hypothetical weakly interacting particles whose mass is constrained to be on the sub-eV range. If these particles exist and interact with electrons, they would be emitted from the dense interior of white dwarfs, becoming an important energy sink for the star. Due to their well known physics, white dwarfs are good laboratories to study the properties of fundamental particles such as the axions. We study the general effect of axion emission on the evolution of helium-rich white dwarfs and on their pulsational properties. To this aim, we calculate evolutionary helium-rich white dwarf models with axion emission, and asses the pulsational properties of this models. Our results indicate that the rates of change of pulsation periods are significantly affected by the existence of axions. We are able for the first time to independently constrain the mass of the axion from the study of pulsating helium-rich white dwarfs. To do this, we use an estimation of the rate of change of period of the pulsating white dwarf PG 1351+489 corresponding to the dominant pulsation period. From an asteroseismological model of PG 1351+489 we obtain $g_{ae}<3.3\times 10^{-13}$ for the axion-electron coupling constant, or $m_a{\cos }^2\beta \lesssim$ 11.5 meV for the axion mass. This constraint is relaxed to $g_{ae}<5.5\times 10^{-13}$ ($m_a{\cos }^2\beta \lesssim$ 19.5 meV), when no detailed asteroseismological model is adopted for the comparison with observations.

    ↳ astro-ph.SRhep-phJCAP(2016)·46 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.