Fri·Apr 29, 2016Friday·April 29, 2016

1. 01*

   Compact Perturbative Expressions For Neutrino Oscillations in Matter

   Peter B. Denton🇺🇸 · Hisakazu Minakata🇧🇷 · Stephen J. Parke🇺🇸

   We further develop and extend a recent perturbative framework for neutrino oscillations in uniform matter density so that the resulting oscillation probabilities are accurate for the complete matter potential versus baseline divided by neutrino energy plane. This extension also gives the exact oscillation probabilities in vacuum for all values of baseline divided by neutrino energy. The expansion parameter used is related to the ratio of the solar to the atmospheric $\Delta m^2$ scales but with a unique choice of the atmospheric $\Delta m^2$ such that certain first-order effects are taken into account in the zeroth-order Hamiltonian. Using a mixing matrix formulation, this framework has the exceptional feature that the neutrino oscillation probability in matter has the same structure as in vacuum, to all orders in the expansion parameter. It also contains all orders in the matter potential and $\sin {\theta }_{13}$. It facilitates immediate physical interpretation of the analytic results, and makes the expressions for the neutrino oscillation probabilities extremely compact and very accurate even at zeroth order in our perturbative expansion. The first and second order results are also given which improve the precision by approximately two or more orders of magnitude per perturbative order.

   hep-phhep-exJHEP(2016)·98 citations
2. 02*

   Sum rules for interaction of ${\rm Y}$ resonances with $Z_b\pi$

   M.B. Voloshin🇺🇸

   The strength of the amplitudes for the coupling between the bottomonium ${\rm Y}(nS)$ states, the bottomonium-like isovector resonances $Z_b$ and a pion, ${\rm Y}(nS)Z_b\pi$, is considered. These amplitudes describe the decays $Z_b\to {\rm Y}(nS)\pi$ for $n=1,2,3$, and the processes ${\rm Y}(nS)\to Z_b\pi$ for $n=5,6,\dots$ with either $Z_b(10610)$ or $Z_b(10650)$. It is pointed out that analyticity and unitarity impose a sum rule for these couplings to each of the $Z_b$ resonances. With the currently available data it appears to be difficult or impossible to simultaneously satisfy the sum rules for the $Z_b(10610)$ and $Z_b(10650)$ resonances. This difficulty can be resolved if there is a considerable dissimilarity in the yield of the states $Z_b(10610)\pi$ and $Z_b(10650)\pi$ in the $e^{+}{e}^{-}$ annihilation at energies above the ${\rm Y}(5S)$ resonance.

   hep-phhep-exPRD(2016)·3 citations
3. 03*

   On the Detectability of Light Dark Matter with Superfluid Helium

   Katelin Schutz🇺🇸 · Kathryn M. Zurek🇺🇸

   We show that a two-excitation process in superfluid helium, combined with sensitivity to meV energy depositions, can probe dark matter down to the ~keV warm dark matter mass limit. This mass reach is three orders of magnitude below what can be probed with ordinary nuclear recoils in helium at the same energy resolution. For dark matter lighter than $\sim 100$ keV, the kinematics of the process requires the two athermal excitations to have nearly equal and opposite momentum, potentially providing a built-in coincidence mechanism for controlling backgrounds.

   hep-phastro-ph.COcond-mat.otherhep-thPRL(2016)·205 citations
4. 04*

   Twin Baryogenesis

   Marco Farina🇺🇸 · Angelo Monteux🇺🇸 · Chang Sub Shin🇺🇸

   In the context of Twin Higgs models, we study a simple mechanism that simultaneously generates asymmetries in the dark and visible sector through the out-of-equilibrium decay of a TeV scale particle charged under a combination of baryon and twin baryon number. We predict the dark matter to be a 5 GeV twin baryon, which is easy to achieve because of the similarity between the two confinement scales. Dark matter is metastable and can decay to three quarks, yielding indirect detection signatures. The mechanism requires the introduction of a new colored particle, typically within the reach of the LHC, of which we study the rich collider phenomenology, including prompt and displaced dijets, multi-jets, monojets and monotops.

   hep-phhep-exPRD(2016)·84 citations
5. 05*

   Leptogenesis and gravity: baryon asymmetry without decays

   J. I. McDonald🇬🇧 · G. M. Shore🇬🇧

   A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

   hep-phgr-qchep-thPLB(2017)·16 citations
6. 06*

   A $L_{\mu }-L_{\tau }$ theory of Higgs flavor violation and $(g-2{)}_{\mu }$

   Wolfgang Altmannshofer🇺🇸 · Marcela Carena🇺🇸 · Andreas Crivellin🇨🇭

   Several experiments reported hints for the violation of lepton flavor or lepton flavor universality in processes involving muons. Most prominently, there is the hint for a non-zero rate of the flavor violating Higgs decay $h\to \tau \mu$ at the LHC, as well as the hint for lepton flavor universality violation in rare $B$ meson decays at LHCb. In addition, also the long standing discrepancy in the anomalous magnetic moment of the muon motivates new physics connected to muons. A symmetry which violates lepton flavor universality, is $L_{\mu }-L_{\tau }$: the difference of muon-number and tau-number. We show that adding vector-like fermions to a $L_{\mu }-L_{\tau }$ theory generates naturally an effect in the anomalous magnetic moment of the muon and $h\to \tau \mu$, while effects in other $\tau \to \mu$ transitions are systematically suppressed by symmetry arguments. We find that if $L_{\mu }-L_{\tau }$ is gauged it is possible to also accommodate the discrepant $b\to s\mu \mu$ data while predicting a $\tau \to 3\mu$ and a modified $h\to \mu \mu$ rate within reach of upcoming experiments.

   hep-phhep-exPRD(2016)·120 citations
7. 07*

   Simple and Accurate Oscillation Probabilities for Three Coupled Neutrinos Propagating in Matter

   Mikkel B. Johnson🇺🇸 · Leonard S. Kisslinger🇺🇸

   Within a conventional Hamiltonian description, we find accurate closed-form expressions for the oscillation probabilities of three coupled neutrinos propagating in matter. Subtle cancelations that occur in coefficients of our formulation are avoided for all transitions ${\nu }_a\to {\nu }_b$ by transforming to a different set of coefficients presented in an appendix of this paper. The neutrino mass eigenvalues are easily obtained numerically as the solution of a cubic equation. Our methods are illustrated for flavor-changing transitions in the $({\nu }_e,{\nu }_{\mu })$ sector. The resulting analytic expressions oscillation probabilities, which are particularly simple, are also accurate to a few percent over all regions of interest at present and the envisioned future neutrino facilities. While somewhat less accurate than numerical simulations, our approximate expressions are sufficiently accuracy to obviate the need for exact computer simulations in many circumstances.

   hep-ph0 citations
8. 08*

   Holographic Picture of Heavy Vector Meson Melting

   Nelson R. F. Braga🇧🇷 · M. A. Martin Contreras🇨🇴 · Saulo Diles🇧🇷

   The fraction of heavy vector mesons produced in a heavy ion collision, as compared to a proton proton collision, serves as an important indication of the formation of a thermal medium, the quark gluon plasma. This sort of analysis strongly depends on understanding the thermal effects of a medium like the plasma on the states of heavy mesons. In particular, it is crucial to know the temperature ranges where they undergo a thermal dissociation, or melting. AdS/QCD models are know to provide an important tool for the calculation of hadronic masses, but in general are not consistent with the observation that decay constants of heavy vector mesons decrease with excitation level. It has recently been shown that this problem can be overcome using a soft wall background and introducing an extra energy parameter, through the calculation of correlation functions at a finite position of anti-de Sitter space. This approach leads to the evaluation of masses and decay constants of S wave quarkonium states with just one flavor dependent and one flavor independent parameters. Here we extend this more realistic model to finite temperatures and analyse the thermal behavior of the states $1S,2S$ and $3S$ of bottomonium and charmonium. The corresponding spectral function exhibits a consistent picture for the melting of the states where, for each flavor, the higher excitations melt at lower temperatures. We estimate for these six states, the energy ranges in which the heavy vector mesons undergo a transition from a well defined peak in the spectral function to complete melting in the thermal medium. A very clear distinction between the heavy flavors emerges, with bottomonium state ${\rm Y}(1S)$ surviving deconfinemet transition at temperatures much larger than the critical deconfinement temperature of the medium.

   hep-phhep-thEPJC(2016)·48 citations
9. 09*

   Factorization of Radiative Leptonic Decays of $B^{-}$ and $D^{-}$ Mesons Including the Soft Photon Region

   Ji-Chong Yang🇨🇳 · Mao-Zhi Yang🇨🇳

   In this work, we study the radiative leptonic decays of $B^{-}$ and $D^{-}$ mesons using factorization approach. Factorization is proved to be valid explicitly at 1-loop level at any order of $O({\Lambda }_{\mathrm{QCD}}/m_Q)$. We consider the contribution in the soft photon region that $E_{\gamma }\sim {\Lambda }_{\mathrm{QCD}}^2/m_Q$. The numerical results shows that, the soft photon region is very important for both the $B$ and $D$ mesons. The branching ratios of $B\to \gamma e{\nu }_e$ is $5.21\times 10^{-6}$, which is about $3$ times of the result obtained by only considering the hard photon region $E_{\gamma }\sim m_Q$. And for the case of $D\to \gamma e{\nu }_e$, the result of the branching ratio is $1.92\times 10^{-5}$.

   hep-phNPB(2017)·11 citations
10. 10*

    Probing the origin of 750 GeV diphoton excess with the precision measurements at the ILC

    Kyu Jung Bae🇯🇵 · Koichi Hamaguchi🇯🇵 · Takeo Moroi🇯🇵 · Keisuke Yanagi🇯🇵

    The recently reported diphoton excess at the LHC may imply the existence of a new resonance with a mass of about 750 GeV which couples to photons via loops of new charged particles. In this letter, we study the possibility to test such models at the ILC, paying attention to the new charged particles responsible for the diphoton decay of the resonance. We show that they affect the scattering processes $e^{+}{e}^{-}\to f\bar{f}$ (with $f$ denoting Standard Model fermions) at the ILC, which makes it possible to indirectly probe the new charged particles even if they are out of the kinematical reach. We also show that the discriminations of the diphoton models may be possible based on a study of the angular distributions of $f\bar{f}$.

    hep-phPLB(2016)·6 citations
11. 11*

    Jet-dilepton conversion from an anisotropic quark-gluon plasma

    Arghya Mukherjee🇮🇳 · Mahatsab Mandal🇮🇳 · Pradip Roy🇮🇳

    We calculate the yield of lepton pair production from jet-plasma interaction where the plasma is anisotropic in momentum space. We compare both the $M$ and $p_T$ distributions from such process with the Drell-Yan contribution. It is observed that the invariant mass distribution of lepton pair from such process dominate over the Drell-Yan up to $3$ GeV at RHIC and up to $10$ GeV at LHC. Moreover, it is found that the contribution from anistropic quark gluon plasma (AQGP) increases marginally compared to the isotropic QGP. In case of $p_T$-distribution we observe an increase by a factor of $3-4$ in the entire $p_T$-range at RHIC for AQGP. However, at LHC the change in the $p_T$-distribution is marginal as compared to the isotropic case.

    hep-phEPJA(2017)·6 citations
12. 12*

    Masses of Third Family Vector-like Quarks and Leptons in Yukawa-Unified $E_6$

    Aditya Hebbar🇺🇸 · George K. Leontaris🇬🇷 · Qaisar Shafi🇺🇸

    In supersymmetric $E_6$ the masses of the third family quarks and charged lepton, $t-b-\tau$, as well as the masses of the vector-like quarks and leptons, $D-\bar{D}$ and $L-\bar{L}$, may arise from the coupling $27_3$ x $27_3$ x $27_H$, where $27_3$ and $27_H$ denote the third family matter and Higgs multiplets respectively. We assume that the SO(10) singlet component in $27_H$ acquires a TeV scale VEV which spontaneously breaks U(1)${}_{\psi }$ and provides masses to the vector-like particles in $27_3$, while the MSSM doublets in $27_H$ provide masses to $t,b$ and $\tau$. Imposing Yukawa coupling unification $h_t=h_b=h_{\tau }=h_D=h_L$ at $M_{GUT}$ and employing the ATLAS and CMS constraints on the $Z_{\psi }^{\prime }$ boson mass, we estimate the lower bounds on the third family vector-like particles $D-\bar{D}$ and $L-\bar{L}$ masses to be around 5.85 TeV and 2.9 TeV respectively. These bounds apply in the supersymmetric limit.

    hep-phPRD(2016)·8 citations
13. 13*

    Cancellation of Infrared Divergence in Inclusive Production of Lepton Pair Near the Threshold of Heavy Quarkonia

    Gao-Liang Zhou🇨🇳

    The detailed proof of cancellation of topologically unfactorized infrared divergences in the inclusive production of lepton pair close to the threshold of heavy quarkonia is presented. To make the effects of transition between states containing heavy quark pairs, which is important in such cancellation, the final detected states are constrained to be lepton pair near the threshold of the heavy quarkonia instead of heavy quarkonia themselves. Such cancellation is crucial for the NRQCD factorization of these processes.

    hep-ph0 citations
14. 14*

    Lepton mixing and neutrino masses from A5 and CP

    Andrea Di Iura🇮🇹

    Some properties of lepton mixing and neutrino masses can be computed under the assumption of A5 and CP as a symmetry in the leptonic sector. The results show that four mixing patterns accommodate well the oscillation data, i.e. all the mixing angles are in the 3sigma confidence region. We also introduce an explicit realization of this framework in the case of the Weinberg operator where the neutrino mass spectrum can be computed.

    hep-ph4 citations
15. 15*

    Neutrino energy reconstruction in long-baseline experiments

    Erica Vagnoni🇮🇹

    Modern experiments aimed at measuring neutrino oscillation parameters have entered the age of precision. The determination of these parameters strongly depends on the ability to reconstruct the energy distributions of the neutrino beams. We compare two different energy reconstruction techniques: the reconstruction based on the kinematic of the outgoing lepton and the one based on the calorimetric method. Furthermore, we analyze realistic detector capabilities, such as energy resolutions, thresholds and efficiencies, in order to estimate how well they need to be evaluated to avoid a significant bias in the extraction of the oscillation parameters.

    hep-ph0 citations
16. 16*

    CPT-symmetry studies with antihydrogen

    Ralf Lehnert🇺🇸

    Various approaches to physics beyond the Standard Model can lead to small violations of CPT invariance. Since CPT symmetry can be measured with ultrahigh precision, CPT tests offer an interesting phenomenological avenue to search for underlying physics. We discuss this reasoning in more detail, comment on the connection between CPT and Lorentz invariance, and review how CPT breaking would affect the (anti)hydrogen spectrum.

    hep-phHyperfine Interact.(2012)·1 citation
17. 17*

    The role of heavy quarks in light hadron fragmentation

    M. Epele🇦🇷 · C. A. Garcia Canal🇦🇷 · R. Sassot🇦🇷

    We investigate the role of heavy quarks in the production of light flavored hadrons and in the determination of the corresponding non perturbative hadronization probabilities. We define a general mass variable flavor number scheme for fragmentation functions that accounts for heavy quark mass effects, and perform a global QCD analysis to an up-to-date data set including very precise Belle and BaBar results. We show that the mass dependent picture provides a much more accurate and consistent description of data.

    hep-phPRD(2016)·13 citations
18. 18*

    Missing energy signature from invisible decays of dark photons at the CERN SPS

    S.N. Gninenko🇷🇺 · N.V. Krasnikov🇷🇺 · M.M. Kirsanov🇷🇺 · D.V. Kirpichnikov🇷🇺

    The dark photon ($A^{\prime }$) production through the mixing with the bremsstrahlung photon from the electron scattering off nuclei can be accompanied by the dominant invisible $A^{\prime }$ decay into dark-sector particles. In this work we discuss the missing energy signature of this process in the experiment NA64 aiming at the search for $A^{\prime }\to invisible$ decays with a high-energy electron beam at the CERN SPS. We show the distinctive distributions of variables that can be used to distinguish the $A^{\prime }\to invisible$ signal from background. The results of the detailed simulation of the detector response for the events with and without $A^{\prime }$ emission are presented. The efficiency of the signal event selection is estimated. It is used to evaluate the sensitivity of the experiment and show that it allows to probe the still unexplored area of the mixing strength $10^{-6}\lesssim ϵ\lesssim 10^{-2}$ and masses up to $M_{A^{\prime }}\lesssim 1$ GeV. The results obtained are compared with the results from other calculations. In the case of the signal observation, a possibility of extraction of the parameters $M_{A^{\prime }}$ and $ϵ$ by using the missing energy spectrum shape is discussed. We consider as an example the $A^{\prime }$ with the mass 16.7 MeV and mixing $ϵ\lesssim 10^{-3}$, which can explain an excess of events recently observed in nuclear transitions of an excited state of ${}^8$Be. We show that if such $A^{\prime }$ exists its invisible decay can be observed in NA64 within a month of running, while data accumulated during a few months would allow also to determine the $ϵ$ and $M_{A^{\prime }}$ parameters.

    hep-phhep-exPRD(2016)·63 citations
19. 19*

    Unified description of seagull cancellations and infrared finiteness of gluon propagators

    A. C. Aguilar🇧🇷 · D. Binosi🇮🇹 · C. T. Figueiredo🇧🇷 · J. Papavassiliou🇪🇸

    We present a generalized theoretical framework for dealing with the important issue of dynamical mass generation in Yang-Mills theories, and, in particular, with the infrared finiteness of the gluon propagators, observed in a multitude of recent lattice simulations. Our analysis is manifestly gauge-invariant, in the sense that it preserves the transversality of the gluon self-energy, and gauge-independent, given that the conclusions do not depend on the choice of the gauge-fixing parameter within the linear covariant gauges. The central construction relies crucially on the subtle interplay between the Abelian Ward identities satisfied by the nonperturbative vertices and a special integral identity that enforces a vast number of 'seagull cancellations' among the one- and two-loop dressed diagrams of the gluon Schwinger-Dyson equation. The key result of these considerations is that the gluon propagator remains rigorously massless, provided that the vertices do not contain (dynamical) massless poles. When such poles are incorporated into the vertices, under the pivotal requirement of respecting the gauge symmetry of the theory, the terms comprising the Ward identities conspire in such a way as to still enforce the total annihilation of all quadratic divergences, inducing, at the same time, residual contributions that account for the saturation of gluon propagators in the deep infrared.

    hep-phhep-lathep-thPRD(2016)·42 citations
20. 20*

    Light-front holographic QCD with generic dilaton profile

    Zhaoheng Guo🇨🇳 · Tianbo Liu🇺🇸 · Bo-Qiang Ma🇨🇳

    We generalize the soft-wall and hard-wall models to a light-front holographic QCD model with a generic dilaton profile. The effective potential induced by a higher power dilaton profile is interpreted as a stronger color confinement at long distance, and it gradually evolves to the hard-wall model when the power increases to infinity. As an application, we investigate the exotic meson states recently discovered in experiments in the generic soft-wall model with a higher power dilaton profile, and the results are in agreement with the spectra of the exotic mesons. Our calculation indicates a weaker interaction at short distance and a stronger interaction at large distance for the components in the exotic mesons. The generic dilaton profile deserves further scrutiny for understanding the strong interaction and for applications.

    hep-phPRD(2016)·4 citations
21. 21*

    Polarized 3 parton production in inclusive DIS at small x

    A. Ayala🇲🇽 · M. Hentschinski🇲🇽 · J. Jalilian-Marian🇺🇸 · M. E. Tejeda-Yeomans🇲🇽

    Azimuthal angular correlations between produced hadrons/jets in high energy collisions are a sensitive probe of the dynamics of QCD at small x. Here we derive the triple differential cross section for inclusive production of 3 polarized partons in DIS at small x using the spinor helicity formalism. The target proton or nucleus is described using the Color Glass Condensate (CGC) formalism. The resulting expressions are used to study azimuthal angular correlations between produced partons in order to probe the gluon structure of the target hadron or nucleus. Our analytic expressions can also be used to calculate the real part of the Next to Leading Order (NLO) corrections to di-hadron production in DIS by integrating out one of the three final state partons.

    hep-phPLB(2016)·51 citations
22. 22*

    Global properties of proton-proton collisions at $\sqrt{s}$ = 100 TeV

    David d'Enterria🇨🇭 · Tanguy Pierog🇩🇪

    The global properties of the final states produced in hadronic interactions of protons at centre-of-mass energies of future hadron colliders (such as FCC-hh at CERN, and SppC in China), are studied. The predictions of various Monte Carlo (MC) event generators used in collider physics (PYTHIA 6, PYTHIA 8, and PHOJET) and in ultrahigh-energy cosmic-rays studies (EPOS, and QGSJET) are compared. Despite their different underlying modeling of hadronic interactions, their predictions for proton-proton (p-p) collisions at $\sqrt{s}$ = 100 TeV are quite similar. The average of all MC predictions (except PHOJET) for the different observables are: (i) p-p inelastic cross sections ${\sigma }_{\mathrm{inel}}$ = 105 $\pm$ 2 mb; (ii) total charged multiplicity ${\mathrm{N}}_{{}_{\mathrm{ch}}}$ = 150 $\pm$ 20; (iii) charged particle pseudorapidity density at midrapidity $\mathrm{d}{\mathrm{N}}_{\mathrm{ch}}/d\eta {|}_{\eta =0}=9.6\pm 0.2$; (iv) energy density at midrapidity $dE/d\eta {|}_{\eta =0}=13.6\pm 1.5$ GeV, and $dE/d\eta {|}_{\eta =5}=670\pm 70$ GeV at the edge of the central region; and (v) average transverse momenta at midrapidities $<{\mathrm{p}}_{\mathrm{T}}>=0.76\pm 0.07$ GeV/c. At midrapidity, EPOS and QGSJET-II predict larger per-event multiplicity probabilities at very low (${\mathrm{N}}_{\mathrm{ch}}<3$) and very high (${\mathrm{N}}_{\mathrm{ch}}>100$) particle multiplicities, whereas PYTHIA 6 and 8 feature higher yields in the intermediate region ${\mathrm{N}}_{\mathrm{ch}}\approx$ 30--80. These results provide useful information for the estimation of the detector occupancies and energy deposits from pileup collisions at the expected large FCC-hh/SppC luminosities.

    hep-phastro-ph.HEhep-exJHEP(2016)·27 citations
23. 23*

    Combined Preheating on the lattice with applications to Higgs inflation

    Joël Repond🇨🇭 · Javier Rubio🇨🇭

    We use classical lattice simulations in 3+1 dimensions to study the interplay between the resonant production of particles during preheating and the subsequent decay of these into a set of secondary species. We choose to work in a simplified version of Higgs inflation in which the Higgs field non-minimally coupled to gravity plays the role of the inflaton. Our numerical results extend the analytical estimates in the literature beyond the linear regime and shed some light on the limitations of the analytical techniques. The inclusion of fast and inefficient decays postpones the onset of parametric resonance by depleting the particles produced at the bottom of the potential. In spite of this delay, fermions are shown to play an important role on the destruction of the inflaton field. The limitations of our approach and its applications to a realistic Higgs inflation scenario are also discussed.

    ↳ astro-ph.COgr-qchep-phJCAP(2016)·107 citations
24. 24*

    Short review of ITEP TH results, 1946-2015

    A.D. Dolgov🇷🇺 · V.A. Novikov🇷🇺 · M.I. Vysotsky🇷🇺

    We review some prominent results of ITEP theorists obtained in the first 70 years of the Institute operation

    ↳ physics.hist-phhep-ph0 citations
25. 25*

    Relativistic model of 2p-2h meson exchange currents in (anti)neutrino scattering

    I. Ruiz Simo🇪🇸 · J.E. Amaro🇪🇸 · M.B. Barbaro🇮🇹 · A. De Pace🇮🇹 · J.A. Caballero🇪🇸 · T.W. Donnelly🇺🇸

    We develop a model of relativistic, charged meson-exchange currents (MEC) for neutrino-nucleus interactions. The two-body current is the sum of seagull, pion-in-flight, pion-pole and $\Delta$-pole operators. These operators are obtained from the weak pion-production amplitudes for the nucleon derived in the non-linear $\sigma$-model together with weak excitation of the $\Delta (1232)$ resonance and its subsequent decay into $N\pi$. With these currents we compute the five 2p-2h response functions contributing to $({\nu }_l,l^{-})$ and $({\overline{\nu }}_l,l^{+})$ reactions in the relativistic Fermi gas model. The total current is the sum of vector and axial two-body currents. The vector current is related to the electromagnetic MEC operator that contributes to electron scattering. This allows one to check our model by comparison with the results of De Pace {\em et al.,} Nuclear Physics A 726 (2003) 303. Thus our model is a natural extension of that model to the weak sector with the addition of the axial MEC operator. The dependences of the response functions on several ingredients of the approach are analyzed. Specifically we discuss relativistic effects, quantify the size of the direct-exchange interferences, and the relative importance of the axial versus vector current.

    ↳ nucl-thhep-phJ.Phys.G(2017)·121 citations
26. 26*

    Berry phase in lattice QCD

    Arata Yamamoto🇯🇵

    We propose the lattice QCD calculation of the Berry phase which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation.

    ↳ hep-lathep-phhep-thPRL(2016)·10 citations
27. 27*

    Critical endpoint in the presence of a chiral chemical potential

    Zhu-Fang Cui🇨🇳 · Ian C. Cloet🇺🇸 · Ya Lu🇨🇳 · Craig D. Roberts🇺🇸 · Sebastian M. Schmidt🇩🇪 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳

    A class of Polyakov-loop-modified Nambu--Jona-Lasinio (PNJL) models have been used to support a conjecture that numerical simulations of lattice-regularized quantum chromodynamics (QCD) defined with a chiral chemical potential can provide information about the existence and location of a critical endpoint in the QCD phase diagram drawn in the plane spanned by baryon chemical potential and temperature. That conjecture is challenged by conflicts between the model results and analyses of the same problem using simulations of lattice-regularized QCD (lQCD) and well-constrained Dyson-Schwinger equation (DSE) studies. We find the conflict is resolved in favor of the lQCD and DSE predictions when both a physically-motivated regularization is employed to suppress the contribution of high-momentum quark modes in the definition of the effective potential connected with the PNJL models and the four-fermion coupling in those models does not react strongly to changes in the mean-field that is assumed to mock-up Polyakov loop dynamics. With the lQCD and DSE predictions thus confirmed, it seems unlikely that simulations of lQCD with ${\mu }_5>0$ can shed any light on a critical endpoint in the regular QCD phase diagram.

    ↳ nucl-thhep-lathep-phnucl-exPRD(2016)·53 citations
28. 28*

    Moduli Vacuum Misalignment and Precise Predictions in String Inflation

    Michele Cicoli🇮🇹 · Koushik Dutta🇮🇳 · Anshuman Maharana🇮🇳 · Fernando Quevedo🇮🇹

    The predictions for all the cosmological observables of any inflationary model depend on the number of e-foldings which is sensitive to the post-inflationary history of the universe. In string models the generic presence of light moduli leads to a late-time period of matter domination which lowers the required number of e-foldings and, in turn, modifies the exact predictions of any inflationary model. In this paper we compute exactly the shift of the number of e-foldings in Kaehler moduli inflation which is determined by the magnitude of the moduli initial displacement caused by vacuum misalignment and the moduli decay rates. We find that the preferred number of e-foldings gets reduced from 50 to 45, causing a modification of the spectral index at the percent level. Our results illustrate the importance of understanding the full post-inflationary evolution of the universe in order to derive precise predictions in string inflation. To perform this task it is crucial to work in a setting where there is good control over moduli stabilisation.

    ↳ hep-thastro-ph.COhep-phJCAP(2016)·77 citations
29. 29*

    Searching for an oscillating massive scalar field as a dark matter candidate using atomic hyperfine frequency comparisons

    A. Hees🇺🇸 · J. Guéna🇫🇷 · M. Abgrall🇫🇷 · S. Bize🇫🇷 · P.Wolf🇫🇷

    We use six years of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant, and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.

    ↳ gr-qchep-phphysics.atom-phPRL(2016)·249 citations
30. 30*

    Simultaneous observation of gravitational and electromagnetic waves

    Vincenzo Branchina🇮🇹 · Manlio De Domenico🇪🇸

    Assuming that the short gamma-ray burst detected by the Fermi Gamma-Ray Space Telescope about 0.4 seconds after the gravitational waves observed by the LIGO and VIRGO Collaborations originated from the same black hole merger event, we perform a model-independent analysis of different quantum gravity scenarios based on (modified) dispersion relations (typical of quantum gravity models) for the graviton and the photon. We find that only scenarios where at least one of the two particles is luminal (the other being sub- or super-luminal) are allowed, while scenarios where none of the two particles is luminal are ruled out. Moreover, the physical request of having acceptable values for the quantum gravity scale imposes stringent bounds on the difference between the velocities of electromagnetic and gravitational waves, much more stringent than any previously known bound.

    ↳ gr-qcastro-ph.HEhep-phhep-th12 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.