Tue·Dec 1, 2015Tuesday·December 1, 2015

1. 01*

   Comparative Analysis of Brookhaven National Laboratory Nuclear Decay Data and Super-Kamiokande Neutrino Data: Indication of a Solar Connection

   P.A. Sturrock🇺🇸 · E. Fischbach🇺🇸

   An experiment carried out at the Brookhaven National Laboratory from February 1982 to December 1989 acquired 364 measurements of the beta-decay rates of a sample of 36Cl and of a sample of 32Si. The experimenters reported finding small periodic annual deviations of the data points from an exponential decay - of uncertain origin. We here analyze this dataset by power spectrum analysis and by forming spectrograms and phasegrams. We confirm the occurrence of annual oscillations but we also find evidence of oscillations in a band of frequencies appropriate for the internal rotation of the Sun. Both datasets show clear evidence of a transient oscillation with a frequency of 12.7 cycles per year that falls in the range of rotational frequencies for the solar radiative zone. We repeat these analyses for 358 neutrino measurements acquired by Super-Kamiokande over the interval May 1986 to August 2001. Spectrogram analysis yields a strong and steady oscillation at about 9.5 cycles per year and an intermittent oscillation with frequency in the range 12.5 - 12.7 cycles per year. We attribute the former to rotation of the solar core and the latter to rotation in the radiative zone. Since the flux of neutrinos (8B neutrinos) responsible for the Super-Kamiokande measurements is known, we are able to estimate the cross sections for the beta-decay oscillations at 12.7 cycles per year. These estimates are found to be 10-21.6 cm-2 for 36Cl and 10-18.4 cm-2 for 32Si. We suggest that the beta-decay process is influenced by neutrinos, and that the solar neutrino flux is modulated by magnetic field in the deep solar interior by Resonant Spin Flavor Precession.

   hep-phastro-ph.SR4 citations
2. 02*

   Model-Independent Indirect Detection Constraints on Hidden Sector Dark Matter

   Gilly Elor🇺🇸 · Nicholas L. Rodd🇺🇸 · Tracy R. Slatyer🇺🇸 · Wei Xue🇺🇸

   If dark matter inhabits an expanded "hidden sector", annihilations may proceed through sequential decays or multi-body final states. We map out the potential signals and current constraints on such a framework in indirect searches, using a model-independent setup based on multi-step hierarchical cascade decays. While remaining agnostic to the details of the hidden sector model, our framework captures the generic broadening of the spectrum of secondary particles (photons, neutrinos, e+e- and antiprotons) relative to the case of direct annihilation to Standard Model particles. We explore how indirect constraints on dark matter annihilation limit the parameter space for such cascade/multi-particle decays. We investigate limits from the cosmic microwave background by Planck, the Fermi measurement of photons from the dwarf galaxies, and positron data from AMS-02. The presence of a hidden sector can change the constraints on the dark matter annihilation cross section by up to an order of magnitude in either direction (although the effect can be much smaller). We find that generally the bound from the Fermi dwarfs is most constraining for annihilations to photon-rich final states, while AMS-02 is most constraining for electron and muon final states; however in certain instances the CMB bounds overtake both, due to their approximate independence of the details of the hidden sector cascade. We provide the full set of cascade spectra considered here as publicly available code with examples at http://web.mit.edu/lns/research/CascadeSpectra.html.

   hep-phastro-ph.HEJCAP(2016)·168 citations
3. 03*

   Spin Decomposition of Electron in QED

   Xiangdong Ji🇺🇸 · Andreas Schäfer🇩🇪 · Feng Yuan🇺🇸 · Jian-Hui Zhang🇩🇪 · Yong Zhao🇺🇸

   We perform a systematic study on the spin decomposition of an electron in QED at one-loop order. It is found that the electron orbital angular momentum defined in Jaffe-Manohar and Ji spin sum rules agrees with each other, and the so-called potential angular momentum vanishes at this order. The calculations are performed in both dimensional regularization and Pauli-Villars regularization for the ultraviolet divergences, and they lead to consistent results. We further investigate the calculations in terms of light-front wave functions, and find a missing contribution from the instantaneous interaction in light-front quantization. This clarifies the confusing issues raised recently in the literature on the spin decomposition of an electron, and will help to consolidate the spin physics program for nucleons in QCD.

   hep-phhep-thnucl-thPRD(2016)·25 citations
4. 04*

   Yukawa matrix unification in the Minimal Supersymmetric Standard Model

   Mateusz Iskrzyński🇵🇱

   In this dissertation, the Minimal Supersymmetric Standard Model (MSSM) is studied as a low-energy theory stemming from the $SU(5)$ Grand Unified Theory (GUT). We investigate the possibility of satisfying the minimal $SU(5)$ boundary condition ${\mathbf{Y}}^d={\mathbf{Y}}^{eT}$ for the full $3\times 3$ down-quark and lepton Yukawa matrices at the GUT scale within the $R$-parity conserving MSSM. We give numerical evidence in favour of the statement: There exist regions in the parameter space of the R-parity conserving MSSM for which the unification of the down-quark and lepton Yukawa matrices takes place, while the predicted values of flavour, electroweak and other collider observables are consistent with experimental constraints. Furthermore, we find evidence that the bottom-tau and strange-muon Yukawa unification is possible with a stable MSSM vacuum in the standard form. We investigate two separate scenarios of the soft supersymmetry breaking terms at the GUT scale. In the first one, it is assumed that the soft terms are flavour-diagonal in the super-CKM basis. In such a case, the trilinear Higgs-squark-squark $A$-terms can generate large threshold corrections to ${\mathbf{Y}}^d$ at the superpartner decoupling scale. In effect, the condition ${\mathbf{Y}}^d={\mathbf{Y}}^{eT}$ imposed at the GUT scale can be satisfied. However, the large trilinear terms make the usual Higgs vacuum metastable (though sufficiently long-lived). In the second scenario, we consider non-vanishing flavour off-diagonal entries in the soft SUSY-breaking mass matrices. We show that a non-trivial flavour structure of the soft SUSY-breaking sector can allow a precise bottom-tau and strange-muon Yukawa coupling unification, while satisfying all phenomenological constraints.

   hep-ph0 citations
5. 05*

   CKM mixings from mass matrices with five texture zeros

   Yithsbey Giraldo🇨🇴 · Eduardo Rojas🇨🇴

   In this work we carry out an exhaustive study to find quark mass matrices in the Standard Model~(SM), with the maximum number of texture zeros consistent with the experimental data. We found four viable configurations of five texture zeros that adjust the quark masses, the mixing angles and the CP violation phase, with deviations below $1\sigma$ level respect to the current SM best fit values. One of the most important aspects of this work is an economic procedure to find the texture zeros: we resort to the weak basis transformation method, which, as we will show, exhaustively search every possible configuration. We report various leading order relations between the mixing angles and the quark masses for each case.

   hep-phPRD(2021)·8 citations
6. 06*

   Probing $(g-2{)}_{\mu }$ at the LHC in the paradigm of R-parity violating MSSM

   Amit Chakraborty🇮🇳 · Sabyasachi Chakraborty🇮🇳

   The measurement of the anomalous magnetic moment of the muon exhibits a long standing discrepancy compared to the Standard model prediction. In this paper, we concentrate on this issue in the framework of $R$-parity violating Minimal supersymmetric standard model. Such a scenario provides substantial contribution to the anomalous magnetic moment of the muon while satisfying constraints from low energy experimental observables as well as neutrino mass. In addition, we point out that the implication of such operators satisfying muon $g-2$ are immense from the perspective of the LHC experiment, leading to a spectacular four muon final state. We propose an analysis in this particular channel which might help to settle the debate of R-parity violation as a probable explanation for $(g-2{)}_{\mu }$.

   hep-phPRD(2016)·30 citations
7. 07*

   $\tau$- and $\mu$-physics in a general two Higgs doublet model with $\mu -\tau$ flavor violation

   Yuji Omura🇯🇵 · Eibun Senaha🇹🇼 · Kazuhiro Tobe🇯🇵

   Motivated by the recent CMS excess in a flavor violating Higgs decay $h\to \mu \tau$ as well as the anomaly of muon anomalous magnetic moment (muon g-2), we consider a scenario where both the excess in $h\to \mu \tau$ and the anomaly of muon g-2 are explained by the $\mu -\tau$ flavor violation in a general two Higgs doublet model. We study various processes involving $\mu$ and $\tau$, and then discuss the typical predictions and constraints in this scenario. Especially, we find that the prediction of $\tau \to \mu \gamma$ can be within the reach of the Belle II experiment. We also show that the lepton non-universality between $\tau \to \mu \nu \bar{\nu }$ and $\tau \to e\nu \bar{\nu }$ can be sizable, and hence the analysis of the current Belle data and the future experimental improvement would have an impact on this model. Besides, processes such as $\tau \to \mu l^{+}{l}^{-}(l=e,\mu )$, $\tau \to \mu \eta$, $\mu \to e\gamma$, $\mu \to 3e$, and muon EDM can be accessible, depending on the unknown Yukawa couplings. On the other hand, the processes like $\tau \to e\gamma$ and $\tau \to e{l}^{+}{l}^{-}(l=e,\mu )$ could not be sizable to observe because of the current strong constraints on the $e-\mu$ and $e-\tau$ flavor violations. Then we also conclude that contrary to $h\to \mu \tau$ decay mode, the lepton flavor violating Higgs boson decay modes $h\to e\mu$ and $h\to e\tau$ are strongly suppressed, and hence it will be difficult to observe these modes at the LHC experiment.

   hep-phhep-exPRD(2016)·77 citations
8. 08*

   ATLAS Diboson Excess from Stueckelberg Mechanism

   Wan-Zhe Feng🇩🇪 · Zuowei Liu🇨🇳 · Pran Nath🇺🇸

   We discuss the diboson excess seen by the ATLAS detector around 2 TeV in the LHC run I at $\sqrt{s}=8$ TeV. We explore the possibility that such an excess can arise from a $Z^{\prime }$ boson which acquires mass through a $U(1{)}_X$ Stueckelberg extension. The corresponding $Z^{\prime }$ gauge boson is leptophobic with a mass of around 2 TeV and has interactions with $SU(2{)}_L$ Yang-Mills fields and gauge fields of the hypercharge. The analysis predicts $Z^{\prime }$ decays into $WW$ and $ZZ$ as well as into $Z\gamma$. Further three-body as well as four-body decays of the $Z^{\prime }$ such as $WWZ,WW\gamma ,WWZZ$ etc are predicted. In the analysis we use the helicity formalism which allows us to exhibit the helicity structure of the $Z^{\prime }$ decay processes in an transparent manner. In particular, we are able to show the set of vanishing helicity amplitudes in the decay of the massive $Z^{\prime }$ into two vector bosons due to angular momentum conservation with a special choice of the reference momenta. The residual set of non-vanishing helicity amplitudes are identified. The parameter space of the model compatible with the diboson excess seen by the ATLAS experiment at $\sqrt{s}=8$ TeV is exhibited. Estimate of the diboson excess expected at $\sqrt{s}=13$ TeV with 20 fb${}^{-1}$ of integrated luminosity at LHC run II is also given. It is shown that the $WW$, $ZZ$ and $Z\gamma$ modes are predicted to be in the approximate ratio $1:{\cos }^2{\theta }_W(1+\alpha {\tan }^2{\theta }_W{)}^2/2:(1-\alpha {)}^2{\sin }^2{\theta }_W/2$ where $\alpha$ is the relative strength of the couplings of hypercharge gauge fields to the couplings of the Yang-Mills gauge fields. Thus observation of the $Z\gamma$ mode as well as three-body and four-body decay modes of the $Z^{\prime }$ will provide a definite test of the model and of a possible new source of interaction beyond the standard model.

   hep-phhep-exJHEP(2016)·13 citations
9. 09*

   Interpretation of Angular Distributions of $Z$-boson Production at Colliders

   Jen-Chieh Peng🇺🇸 · Wen-Chen Chang🇹🇼 · Randall Evan McClellan🇺🇸 · Oleg Teryaev🇷🇺

   High precision data of dilepton angular distributions in ${\gamma }^{\ast }/Z$ production were reported recently by the CMS Collaboration covering a broad range of the dilepton transverse momentum, $q_T$, up to $\sim 300$ GeV. Pronounced $q_T$ dependencies of the $\lambda$ and $\nu$ parameters, characterizing the ${\cos }^2\theta$ and $\cos 2\varphi$ angular distributions, were found. Violation of the Lam-Tung relation was also clearly observed. We show that the $q_T$ dependence of $\lambda$ allows a determination of the relative contributions of the $q\bar{q}$ annihilation versus the $qG$ Compton process. The violation of the Lam-Tung relation is attributed to the presence of a non-zero component of the $q-\bar{q}$ axis in the direction normal to the "hadron plane" formed by the colliding hadrons. The magnitude of the violation of the Lam-Tung relation is shown to reflect the amount of this `non-coplanarity". The observed $q_T$ dependencies of $\lambda$ and $\nu$ from the CMS and the earlier CDF data can be well described using this approach.

   hep-phhep-exnucl-exPLB(2016)·52 citations
10. 10*

    125 GeV Higgs decay with lepton flavor violation in the $\mu \nu$SSM

    Hai-Bin Zhang🇨🇳 · Tai-Fu Feng🇨🇳 · Shu-Min Zhao🇨🇳 · Yu-Li Yan🇨🇳 · Fei Sun🇨🇳

    Recently, the CMS and ATLAS Collaborations have reported direct searches for the 125 GeV Higgs decay with lepton flavor violation, $h\to \mu \tau$. In this work, we analyze the signal of the lepton flavour violating (LFV) Higgs decay $h\to \mu \tau$ in the $\mu$ from $\nu$ Supersymmetric Standard Model ($\mu \nu$SSM) with slepton flavor mixing. Simultaneously, we consider the constraints from the LFV decay $\tau \to \mu \gamma$, the muon anomalous magnetic dipole moment and the lightest Higgs mass around 125 GeV.

    hep-phCPC(2017)·34 citations
11. 11*

    Challenging Asymptotic Freedom

    Francesco Sannino🇩🇰

    Several extensions of the standard model feature new colored states that besides modifying the running of the QCD coupling could even lead to the loss of asymptotic freedom. Such a loss would potentially diminish the Wilsonian fundamental value of the theory. However, the recent discovery of complete asymptotically safe vector-like theories \cite{Litim:2014uca}, i.e. featuring an interacting UV fixed point in all couplings, elevates these theories to a fundamental status and opens the door to alternative UV completions of (parts of) the standard model. If, for example, QCD rather than being asymptotically free becomes asymptotically safe there would be consequences on the early time evolution of the Universe (the QCD plasma would not be free). It is therefore important to test, both directly and indirectly, the strong coupling running at the highest possible energies. I will review here the attempts made in \cite{Becciolini:2014lya} to use pure QCD observables at the Large Hadron Collider (LHC) to place bounds on new colored states. Such bounds do not depend on the detailed properties of the new hypothetical states but on their effective number and mass. We will see that these direct constraints cannot exclude a potentially safe, rather than free, QCD asymptotic nature. A safe QCD scenario would imply that quarks and gluons are only approximately free at some intermediate energies, otherwise they are always in chains.

    hep-phhep-lathep-th18 citations
12. 12*

    Perturbative Corrections to ${\Lambda }_b\to \Lambda$ Form Factors from QCD Light-Cone Sum Rules

    Yu-Ming Wang🇦🇹 · Yue-Long Shen🇨🇳

    We compute radiative corrections to ${\Lambda }_b\to \Lambda$ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with ${\Lambda }_b$-baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-${\Lambda }_b$-baryon correlation function is justified at leading power in $\Lambda /m_b$, with the aid of the method of regions. Hard functions entering the factorization formulae are identical to the corresponding matching coefficients of heavy-to-light currents from QCD onto soft-collinear effective theory. The universal jet function from integrating out the hard-collinear fluctuations exhibits richer structures compared with the one involved in the factorization expressions of the vacuum-to-$B$-meson correlation function. Based upon the QCD resummation improved sum rules we observe that the perturbative corrections at $\mathcal{O}({\alpha }_s)$ shift the ${\Lambda }_b\to \Lambda$ from factors at large recoil significantly and the dominant contribution originates from the next-to-leading order jet function instead of the hard coefficient functions. Having at hand the sum rule predictions for the ${\Lambda }_b\to \Lambda$ from factors we further investigate several decay observables in the electro-weak penguin ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$ transitions in the factorization limit (i.e., ignoring the "non-factorizable" hadronic effects which cannot be expressed in terms of the ${\Lambda }_b\to \Lambda$ from factors), including the invariant mass distribution of the lepton pair, the forward-backward asymmetry in the dilepton system and the longitudinal polarization fraction of the leptonic sector.

    hep-phhep-exhep-latJHEP(2016)·120 citations
13. 13*

    The structure of pentaquarks $P_c^{+}$ in the chiral quark model

    Gang Yang🇨🇳 · Jialun Ping🇨🇳

    The recent experimental results of LHCb collaboration suggested the existence of pentaquark states with charmonium. To understand the structure of the states, a dynamical calculation of 5-quark systems with quantum numbers $I{J}^P=\frac{1}{2}(\frac{1}{2}{)}^{\pm }$, $\frac{1}{2}(\frac{3}{2}{)}^{\pm }$ and $\frac{1}{2}(\frac{5}{2}{)}^{\pm }$ is performed in the framework of chiral quark model with the help of gaussian expansion method. The results show that the negative parity states can be bound states while all of the positive parity states are the scattering states. The $P_c(4380)$ state is suggested to be the bound state of ${\Sigma }_c^{\ast }D$. Although the energy of ${\Sigma }_c{D}^{\ast }$ is very close to the mass of $P_c(4450)$, the inconsistent parity prevents the assignment. The calculated distances between quarks confirm the molecular nature of the states. Other five-quark bound states of the combination of ${\Sigma }_{c}D$ and ${\Sigma }_c^{\ast }{D}^{\ast }$ are also found in the region about 4.3GeV and 4.5GeV.

    hep-phnucl-thPRD(2017)·93 citations
14. 14*

    Unraveling flavor & naturalness from RUN II to 100 TeV

    Amarjit Soni🇺🇸

    The importance of incorporating flavor constraints, when providing bounds on new physics is stressed. As is well known it is very difficult for models of new physics to have scales lighter than about 10 TeV once flavor constraints are built in. Although, in the conventional sense, this higher scale means more tuning, it may well make the underlying theory simpler as illustrated with one example. Direct production of new particles heavier than about 5 TeV becomes very difficult at LHC though indirect signals such as deviations in the Higgs to gamma gamma branching ratio may still be possible. Also of course precision studies at low energy facilities can be useful for detecting new phenomena. For direct production of new particles over 5-10 TeV a new high energy collider perhaps at 100 TeV is highly desirable. Indeed, a very strong physics case can be made for such a machine. It can be used to significantly improve many bounds as well as allow a multitude of direct searches in many channels without relying on specific models. Naturalness can be tested by another factor of about 50 past LHC to O($10^{-4}$), a valuable achievement in itself.

    hep-ph0 citations
15. 15*

    Detecting quark anomalous electroweak couplings at the LHC

    Sheng-Zhi Zhao🇨🇳 · Bin Zhang🇨🇳

    We study the dimension-6 quark anomalous electroweak couplings in the formulation of linearly realized effective Lagrangian. We investigate the constraints on these anomalous couplings from the $pp\to W^{+}{W}^{-}$ process in detail at the LHC. With additional kinematic cuts, we find that the 14 TeV LHC can provide a test of anomalous couplings of $O(0.1-1){\mathrm{TeV}}^{-2}$. The $pp\to ZZ/Z\gamma /\gamma \gamma$ processes can provide a good complement as they are sensitive to those anomalous couplings which do not affect the $pp\to W^{+}{W}^{-}$ process. Those processes that only contain anomalous triple vertices, like $pp\to W^{\ast }\to l{\nu }_l$ or $pp\to {\gamma }^{\ast }/Z^{\ast }\to l^{+}{l}^{-}$, can improve the sensitivities to $O(0.01-0.1){\mathrm{TeV}}^{-2}$. We also study the kinematic differences between different anomalous couplings and discuss the potential of the ${\chi }^2$-analysis to distinguish them. Finally, we discuss the detection ability of the possible future 100 TeV proton-proton collider(SPPC), and find that the detection sensitivity is improved by about one order of magnitude compared with the LHC.

    hep-phPRD(2016)·0 citations
16. 16*

    Light Higgsino from $A_t$ Dilemma in Rare $B$-decays

    Ming-xing Luo🇨🇳 · Kai Wang🇨🇳 · Tao Xu🇨🇳 · Liangliang Zhang🇨🇳 · Guohuai Zhu🇨🇳

    In the Minimal Supersymmetric Standard Model (MSSM), large chiral symmetry breaking term $A_t$, which plays an important role in Higgs mass, may significantly contribute in flavor changing neutral current (FCNC) processes $B\to X_s\gamma$ and $B_s\to {\mu }^{+}{\mu }^{-}$. Though the above processes can both be categorized as $b\to s$ transitions, the two rare decays behave completely different in MSSM. With an on-shell photon in the final state, helicity of initial state $b$-quark and final state $s$-quark must be flipped in $B\to X_s\gamma$, which corresponds to the simultaneous breaking of chiral symmetry and electroweak symmetry. The common feature is shared by fermion mass generation. Same as radiative mass generation in MSSM, Peccei-Quinn and $R$ symmetry breaking contributions, for example from a Higgsino-stop loop when $\mu A_t<0$, may significantly cancel the contribution from charged Higgs and reduce the prediction of $B\to X_s\gamma$. For the latter process, including Babu-Kolda FCNC proportional to $\mu A_t$, $B_s\to {\mu }^{+}{\mu }^{-}$ is mediated by a scalar $H_d$ boson which corresponds to chiral symmetry breaking. In addition, as a result of interference among the Higgs extension sector and $Z$ contributions, in the region of $\mu A_t<0$ which is favored by $B\to X_s\gamma$, there may simultaneously exist large enhancement in $B_s\to {\mu }^{+}{\mu }^{-}$. However, we still find viable parameter region with light Higgsino of a few hundreds GeV when charged Higgs contribution is not negligible with $M_A$ of 400 GeV.

    hep-ph0 citations
17. 17*

    Pion in the Medium with a Light-Front Model

    J. P. B. C. de Melo🇧🇷 · Kazuo Tsushima (Laboratório de Física Teórica e Computacional - LFTC - Universidade Cruzeiro do Sul)🇧🇷 · Tobias Frederico (Instituto Tecnológico da Aeronáutica/DCTA)🇧🇷

    The pion properties in symmetric nuclear matter are investigated with the Quark-Meson Coupling (QMC) Model plus the light-front constituent quark model~(LFCQM). The LFCQM has been quite successful in describing the properties of pseudoscalar mesons in vacuum, such as the electromagnetic elastic form factors, electromagnetic radii, and decay constants. We study the pion properties in symmetric nuclear matter with the in-medium input recalculated through the QMC model, which provides the in-medium modification of the LFCQM.

    hep-phnucl-thAIP Conf.Proc.(2016)·5 citations
18. 18*

    High-energy single diffractive dissociation of nucleons and the 3P-model applicability range

    A.A. Godizov🇷🇺

    The adequacy of the triple-Pomeron interaction approximation (the 3P-model) for description of the high-energy single diffractive dissociation of nucleons is analyzed via application to the available experimental data on nucleon-nucleon scattering, including the recent results produced by CMS Collaboration which allow to estimate reliably the triple-Pomeron coupling value. It is argued that the total contribution of secondary Reggeon exchanges is not negligible up to the Tevatron energy.

    hep-phhep-exNPA(2016)·6 citations
19. 19*

    Light neutrino contribution: is it all there is to neutrinoless double beta decay?

    Namit Mahajan🇮🇳

    We consider perturbative one loop QCD corrections to the light neutrino contribution to neutrinoless double beta decay and find large enhancement to the rate. QCD corrections also generate structures which mimic new physics contributions usually considered. Within some approximations, the net effect seem to almost saturate the experimental limits, and therefore seems to implt that this is all there is to neutrinoless double beta decay.

    hep-phhep-exnucl-th1 citation
20. 20*

    The Galactic Center Excess from Z3 Scalar Semi-Annihilations

    Yi Cai🇦🇺 · Andrew Paul Spray🇰🇷

    We investigate the possibility of the Z3 scalar singlet model explaining the Fermi galactic centre excess. We find a good fit to the measured spectral excess in the region where the dark matter mass is comparable to the Higgs and the Higgs portal coupling ${\lambda }_{HS}\sim 0.04$. This preferred region is consistent with constraints from vacuum stability and current dark matter experiments, and will be discovered or falsified soon by future dark matter direct detection experiment.

    hep-phJHEP(2016)·13 citations
21. 21*

    Majorana neutrino mass structure induced by rigid instatons on toroidal orbifold

    Tatsuo Kobayashi🇯🇵 · Yoshiyuki Tatsuta🇯🇵 · Shohei Uemura🇯🇵

    We study effects of D-brane instantons wrapping rigid cycles on Z2*Z2' toroidal orbifold. We compute Majorana masses induced by rigid D-brane instantons and realize bimaximal mixing matrices in certain models. We can also derive more generic mass matrices in other models. The bimaximal mixing Majorana mass matrix has a possibility to explain observed mixing angles. We also compute the mu-term matrix among more than one pairs of Higgs fields induced by rigid D-brane instantons.

    hep-phhep-thPRD(2016)·21 citations
22. 22*

    Landscape View at the Edge of a Mystery

    D.I. Kazakov🇷🇺

    The situation in particle physics after the discovery of the Higgs boson is discussed. Is the Standard Model consistent quantum field theory? Does it describe all experimental data? Are there any indications of physics beyond the SM? Is there another scale except for the EW and the Planck ones? Is the SM of particles physics compatible with Cosmology? New challenges of hadron physics: exotic hadrons and dense hadronic matter. Search for new physics, from the Higgs sector to dark matter, supersymmetry, extra dimensions and compositeness. What do we expect? What are the main targets? We try to answer the main questions and describe the key issues of possible new physics beyond the SM.

    hep-ph2 citations
23. 23*

    A revisit to a compressed supersymmetric spectrum with 125 GeV Higgs

    Juhi Dutta🇮🇳 · Partha Konar🇮🇳 · Subhadeep Mondal🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Santosh Kumar Rai🇮🇳

    A compressed spectrum was initially proposed as an explanation for the elusiveness of low-energy supersymmetry (SUSY). Some characteristic signals at the Large Hadron Collider (LHC), such as mono-jet + \slashed{E}_T, had been propounded as its trademark signals. However, later investigations suggested that lower limits on the supersymmetric particle masses would be quite stringent in spite of compression. Also, most compressed SUSY scenarios studied so far are only partially compressed. In this backdrop, we make an exhaustive analysis of the compressed SUSY scenarios for the 13 TeV run of LHC, keeping the level of compression in the entire spectrum as high as possible. A broad class of benchmark spectra are thus considered, after ensuring consistency with the observed Higgs mass as well as the dark matter constraints. The rates of observable events in the high-energy run are obtained through detailed simulation, for both the multi-jet +\slashed{E}_T and mono-jet + \slashed{E}_T final states. Our conclusion is that the former is still more efficient to reveal a compressed SUSY spectrum first, while the latter can serve as a useful confirmatory channel.

    hep-phhep-exJHEP(2016)·22 citations
24. 24*

    Short path length corrections to Djordjevic-Gyulassy-Levai-Vitev energy loss

    Isobel Kolbé🇿🇦 · W. A. Horowitz🇿🇦

    We compute the correction to the energy loss of a hard parton due to short separation distances between the creation of the particle and the in-medium scattering center that stimulates bremsstrahlung radiation, to first order in opacity. In deriving the result we make full use of the large formation time assumption, which results in a significant reduction of the number of diagrams contributing to the small separation distance correction. An asymptotic analysis of our small separation distance correction term finds that the correction dominates at large $\sim 100$ GeV parent parton energies; scales like $L$ with the size of the system for small $L$, but like $L^0$ at larger $L$; and breaks color triviality. An extensive numerical investigation of the correction term confirms the aforementioned analytic findings, reveals that the correction term does not go to zero for large $L$, finds that the correction is sensitive to the mass of the parent parton, and shows a crucial dependence of the energy loss on a proper treatment of the physics of separation distances on the order of the Debye screening length. However, an examination of the large formation time approximation shows that it is violated for much of the phase space of the emitted radiation, implying a need to investigate the sensitivity of jet quenching results from relaxing this approximation. Our result constitutes an important step toward understanding partonic energy loss in small colliding systems.

    hep-phPRC(2019)·29 citations
25. 25*

    Exploring the Higgs sector of the MRSSM with a light scalar

    Philip Diessner🇩🇪 · Jan Kalinowski🇵🇱 · Wojciech Kotlarski🇩🇪 · Dominik Stöckinger🇩🇪

    In a recent paper we showed that the Minimal R-symmetric Supersymmetric Standard Model (MRSSM) can accommodate the observed 125 GeV Higgs boson as the lightest scalar of the model in agreement with electroweak precision observables, in particular with the W boson mass and $T$ parameter. Here we explore a scenario with the light singlet (and bino-singlino) state in which the second-lightest scalar takes the role of the SM-like boson with mass close to 125 GeV. In such a case the second-lightest Higgs state gets pushed up via mixing already at tree-level and thereby reducing the required loop correction. Unlike in the NMSSM, the light singlet is necessarily connected with a light neutralino which naturally appears as a promising dark matter candidate. We show that dark matter and LHC searches place further bounds on this scenario and point out parameter regions, which are viable and of interest for LHC Run II and upcoming dark matter experiments.

    hep-phJHEP(2016)·49 citations
26. 26*

    QCD and Jets at Hadron Colliders

    Sebastian Sapeta🇨🇭

    We review various aspects of jet physics in the context of hadron colliders. We start by discussing the definitions and properties of jets and recent development in this area. We then consider the question of factorization for processes with jets, in particular for cases in which jets are produced in special configurations, like for example in the region of forward rapidities. We review numerous perturbative methods for calculating predictions for jet processes, including the fixed-order calculations as well as various matching and merging techniques. We also discuss the questions related to non-perturbative effects and the role they play in precision jet studies. We describe the status of calculations for processes with jet vetoes and we also elaborate on production of jets in forward direction. Throughout the article, we present selected comparisons between state-of-the-art theoretical predictions and the data from the LHC.

    hep-phPPNP(2016)·57 citations
27. 27*

    Precise predictions for Higgs-boson production in association with top quarks

    Ansgar Denner🇩🇪 · Robert Feger🇩🇪 · Andreas Scharf🇩🇪

    We analyse the production of a Higgs boson in association with a top--antitop-quark pair in the Standard Model at the LHC. Considering the final state consisting of four b jets, two jets, one identified charged lepton and missing energy, we examine the irreducible background for the production rate and several kinematical distributions. While ttH production and decay is roughly a fourth of the full process for the final state specified above, ttbb production constitutes the main contribution with about $92\%$. Surprisingly, interference effects result in a reduction of the cross-section by five per cent. Furthermore, we consider NLO QCD corrections for the production of a Higgs boson, two charged leptons, two neutrinos, and two b jets. We discuss the size of the corrections and the scale dependence for the integrated cross section and different distributions. For the integrated cross section we find a $K$ factor of 1.17 and a reduction of the scale dependence from $30\%$ at leading order to $5\%$ at next-to-leading order.

    hep-phPoS(2015)·0 citations
28. 28*

    Resonances in QCD

    Matthias F.M. Lutz · Jens Sören Lange · Michael Pennington · Diego Bettoni · Nora Brambilla · Volker Crede · Simon Eidelman · Albrecht Gillitzer · Wolfgang Gradl · Christian B. Lang · Volker Metag · Juan Nieves and 13 other authors

    We report on the EMMI Rapid Reaction Task Force meeting 'Resonances in QCD', which took place at GSI October 12-14, 2015. A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions: What is needed to understand the physics of resonances in QCD? Where does QCD lead us to expect resonances with exotic quantum numbers? What experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with $up$, $down$ and $strange$ quark content were considered. For heavy-light and heavy-heavy meson systems, those with $charm$ quarks were the focus. This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.

    hep-phNPA(2016)·31 citations
29. 29*

    Factorization for forward dijets in dilute-dense collisions

    Elena Petreska🇫🇷

    We propose a factorization formula for the cross section for forward dijet production in dilute-dense collisions. The new formula is applicable for an arbitrary value of the momentum imbalance of the two jets, $k_t$. It unifies the previously derived transverse momentum dependent (TMD) factorization for small $k_t$ (of the order of the saturation scale), and the High Energy Factorization (HEF) for large $k_t$ (of the order of the momentum of the jets). We extend the previous TMD formula, first to finite $N_c$, and then to all ranges of $k_t$ by including off-shell matrix elements. We present previously unpublished analytical expressions for the TMD gluon distributions in the Golec-Biernat-Wusthoff model, and their perturbative behaviour in the McLerran-Venugopalan model. In addition, we show directly the equivalence of the HEF and the color glass condensate formulae in the dilute target approximation.

    hep-phNPA(2016)·5 citations
30. 30*

    The Pentabox Master Integrals with the Simplified Differential Equations approach

    Costas G. Papadopoulos🇬🇷 · Damiano Tommasini🇬🇷 · Christopher Wever🇬🇷

    We present the calculation of massless two-loop Master Integrals relevant to five-point amplitudes with one off-shell external leg and derive the complete set of planar Master Integrals with five on-mass-shell legs, that contribute to many $2\to 3$ amplitudes of interest at the LHC, as for instance three jet production, $\gamma ,V,H+2$ jets etc., based on the Simplified Differential Equations approach.

    hep-phhep-thJHEP(2016)·156 citations
31. 31*

    A View of Neutrino Studies with the Next Generation Facilities

    Luca Stanco🇮🇹

    Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long--standing investigation of new physics beyond the Standard Model. The rather recent measurement of the third mixing angle ${\theta }_{13}$ in the standard mixing oscillation scenario encourages the pursuit of what is still missing: the size of any leptonic CP violation, absolute neutrino masses and the characteristic nature of the neutrino. Several projects are currently running and they are providing impressive results. In this review, the phenomenology of neutrino oscillations that results from the last two decades of investigations is reviewed, with emphasis on our current knowledge and on what lesson can be taken from the past. We then present a critical discussion of current studies on the mass ordering and what might be expected from future results. Our conclusion is that decisions determining the next generation of experiments and investigations have to be strictly based on the findings of the current generation of experiment. In this sense it would be wise to wait a few years before taking decisions on the future projects. In the meantime, since no direct path forward is evident for the future projects, the community must be committed to their careful evaluation.

    hep-phhep-exRev.Phys.(2016)·13 citations
32. 32*

    Heavy quarks in proton-nucleus collisions - the hybrid formalism

    Tolga Altinoluk🇪🇸 · Néstor Armesto🇪🇸 · Guillaume Beuf🇮🇱 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱

    We explore the quark mass effects on inclusive hadron production in proton-nucleus collisions at high energies. We consider two processes. First, we compute the single inclusive cross-section for production of hadrons with open heavy flavour in the proton forward direction at leading order. Next, in the same kinematics, we calculate the heavy-quark contribution to single inclusive production of light or unidentified hadrons at next-to-leading-order. For both studies we exploit the hybrid formalism, that is the collinear factorisation on the proton side while high-density and high-energy effects are resummed on the side of the nucleus.

    hep-phPRD(2016)·26 citations
33. 33*

    Recent progress on chiral symmetry breaking in QCD

    Leonardo Giusti🇮🇹

    I review recent progress achieved on the lattice in the quantitative comprehension of chiral symmetry breaking in QCD. Emphasis is given to the recent precise computations of the spectral density of the Dirac operator in the continuum limit, and of the topological susceptibility.

    ↳ hep-lathep-phhep-thPoS(2016)·4 citations
34. 34*

    $U(1)$ current from the AdS/CFT: diffusion, conductivity and causality

    Yanyan Bu🇮🇱 · Michael Lublinsky🇮🇱 · Amir Sharon🇮🇱

    For a holographically defined finite temperature theory, we derive an off-shell constitutive relation for a global $U(1)$ current driven by a weak external non-dynamical electromagnetic field. The constitutive relation involves an all order gradient expansion resummed into three momenta-dependent transport coefficient functions: diffusion, electric conductivity, and "magnetic" conductivity. These transport functions are first computed analytically in the hydrodynamic limit, up to third order in the derivative expansion, and then numerically for generic values of momenta. We also compute a diffusion memory function, which, as a result of all order gradient resummation, is found to be causal.

    ↳ hep-thhep-phnucl-thJHEP(2016)·24 citations
35. 35*

    Constraints on Primordial Magnetic Fields from Inflation

    Daniel Green🇨🇦 · Takeshi Kobayashi🇨🇦

    We present generic bounds on magnetic fields produced from cosmic inflation. By investigating field bounds on the vector potential, we constrain both the quantum mechanical production of magnetic fields and their classical growth in a model independent way. For classical growth, we show that only if the reheating temperature is as low as T_{reh} <~ 10^2 MeV can magnetic fields of 10^{-15} G be produced on Mpc scales in the present universe. For purely quantum mechanical scenarios, even stronger constraints are derived. Our bounds on classical and quantum mechanical scenarios apply to generic theories of inflationary magnetogenesis with a two-derivative time kinetic term for the vector potential. In both cases, the magnetic field strength is limited by the gravitational back-reaction of the electric fields that are produced simultaneously. As an example of quantum mechanical scenarios, we construct vector field theories whose time diffeomorphisms are spontaneously broken, and explore magnetic field generation in theories with a variable speed of light. Transitions of quantum vector field fluctuations into classical fluctuations are also analyzed in the examples.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2016)·38 citations
36. 36*

    Analysis of the observed and intrinsic durations of $Swift$/BAT gamma-ray bursts

    Mariusz Tarnopolski🇵🇱

    The duration distribution of 947 GRBs observed by $Swift$/BAT, as well as its subsample of 347 events with measured redshift, allowing to examine the durations in both the observer and rest frames, are examined. Using a maximum log-likelihood method, mixtures of two and three standard Gaussians are fitted to each sample, and the adequate model is chosen based on the value of the difference in the log-likelihoods, Akaike information criterion and Bayesian information criterion. It is found that a two-Gaussian is a better description than a three-Gaussian, and that the presumed intermediate-duration class is unlikely to be present in the $Swift$ duration data.

    ↳ astro-ph.HEastro-ph.COhep-phphysics.space-phNew Astron.(2016)·19 citations
37. 37*

    Origin of fermion masses without spontaneous symmetry breaking

    Venkitesh Ayyar🇺🇸 · Shailesh Chandrasekharan (Duke University)🇺🇸

    Using a simple three dimensional lattice four-fermion model we argue that massless fermions can become massive due to interactions without the need for any spontaneous symmetry breaking. Using large scale Monte Carlo calculations within our model, we show that this non-traditional mass generation mechanism occurs at a second order quantum critical point that separates phases with the same symmetries. Universality then suggests that the new origin for the fermion mass should be of wide interest.

    ↳ hep-latcond-mat.str-elhep-phPRD(2016)·86 citations
38. 38*

    $\pi$N and strangeness sigma terms at the physical point with chiral fermions

    Yi-Bo Yang🇺🇸 · Andrei Alexandru🇺🇸 · Terrence Draper🇺🇸 · Jian Liang🇺🇸 · Keh-Fei Liu🇺🇸

    Lattice QCD calculations with chiral fermions of the $\pi$N sigma term ${\sigma }_{\pi N}$ and strangeness sigma term ${\sigma }_{sN}$ including chiral interpolation with continuum and volume corrections are provided in this work, with the excited-state contaminations subtracted properly. We calculate the scalar matrix element for the light/strange quark directly and find ${\sigma }_{\pi N}=45.9(7.4)(2.8)$ MeV, with the disconnected insertion part contributing 20(12)(4)\%, and ${\sigma }_{sN}=40.2(11.7)(3.5)$ MeV, which is somewhat smaller than ${\sigma }_{\pi N}$. The ratio of the strange/light scalar matrix elements is $y$ = 0.09(3)(1).

    ↳ hep-lathep-phPRD(2016)·166 citations
39. 39*

    Transverse spin azimuthal asymmetries in SIDIS at COMPASS: Multidimensional analysis

    Bakur Parsamyan🇮🇹

    One of the important objectives of the COMPASS experiment (CERN, SPS north area) is the exploration of transverse spin structure of nucleon via study of spin (in)dependent azimuthal asymmetries with semi-inclusive deep inelastic scattering (SIDIS) processes and recently also with Drell-Yan (DY) reactions. In the past twelve years series of measurements were made in COMPASS, using 160 GeV/c longitudinally polarized muon beam and polarized ${}^{6}LiD$ and $N{H}_3$ targets. Drell-Yan measurements with high energy (190 GeV/c) pion beam and transversely polarized $N{H}_3$ target started in 2014 with a pilot-run have been followed by 140 days of data taking in 2015. The experimental results obtained by COMPASS for azimuthal effects in SIDIS play an important role in the general understanding of the three-dimensional nature of the nucleon and are widely used in theoretical analyses and global data fits. In addition, future first ever polarized DY-data from COMPASS compared with SIDIS results will open a new chapter probing general principles of QCD TMD-formalism. In this review main focus is given to the very recent results obtained by the COMPASS collaboration from first ever multi-dimensional extraction of SIDIS transverse spin asymmetries.

    ↳ hep-exhep-ph3 citations
40. 40*

    Nucleon-nucleon bremsstrahlung of dark gauge bosons and revised supernova constraints

    Ermal Rrapaj🇺🇸 · Sanjay Reddy🇺🇸

    We calculate the rate of production of hypothetical light vector bosons (LVBs) from nucleon-nucleon bremsstrahlung reactions in the soft radiation limit directly in terms of the measured nucleon-nucleon elastic cross sections. We use these results and the observation of neutrinos from supernova SN1987a to deduce constraints on the couplings of vector bosons with masses $\lesssim 200$ MeV to either electric charge (dark photons) or to baryon number. We establish for the first time strong constraints on LVB that couple only to baryon number, and revise earlier constraints on the dark photon. For the latter, we find that the excluded region of parameter space is diminished by about a factor of 10.

    ↳ nucl-thastro-ph.HEastro-ph.SRhep-phPRC(2016)·126 citations
41. 41*

    N* Spectroscopy from Lattice QCD: The Roper Explained

    Derek Leinweber🇦🇺 · Waseem Kamleh🇦🇺 · Adrian Kiratidis🇦🇺 · Zhan-Wei Liu🇦🇺 · Selim Mahbub🇦🇺 · Dale Roberts🇦🇺 · Finn Stokes🇦🇺 · Anthony W. Thomas🇦🇺 · Jiajun Wu🇦🇺

    This brief review focuses on the low-lying even- and odd-parity excitations of the nucleon obtained in recent lattice QCD calculations. Commencing with a survey of the 2014-15 literature we'll see that results for the first even-parity excitation energy can differ by as much as 1 GeV, a rather unsatisfactory situation. Following a brief review of the methods used to isolate excitations of the nucleon in lattice QCD, and drawing on recent advances, we'll see how a consensus on the low-lying spectrum has emerged among many different lattice groups. To provide insight into the nature of these states we'll review the wave functions and electromagnetic form factors that are available for a few of these states. Consistent with the Luscher formalism for extracting phase shifts from finite volume spectra, the Hamiltonian approach to effective field theory in finite volume can provide guidance on the manner in which physical quantities manifest themselves in the finite volume of the lattice. With this insight, we will address the question; Have we seen the Roper in lattice QCD?

    ↳ hep-lathep-phnucl-thJPS Conf.Proc.(2016)·31 citations
42. 42*

    Two-Loop Quantum Gravity Corrections to Cosmological Constant in Landau Gauge

    Ken-ji Hamada🇯🇵 · Mikoto Matsuda🇯🇵

    The anomalous dimensions of the Planck mass and the cosmological constant are calculated in a renormalizable quantum conformal gravity with a single dimensionless coupling, which is formulated using dimensional regularization on the basis of Hathrell's works for conformal anomalies. The dynamics of the traceless tensor field is handled by the Weyl action, while that of the conformal-factor field is described by the induced Wess-Zumino actions, including the Riegert action as the kinetic term. Loop calculations are carried out in Landau gauge in order to reduce the number of Feynman diagrams as well as to avoid some uncertainty. Especially, we calculate two-loop quantum gravity corrections to the cosmological constant. It suggests that there is a dynamical solution to the cosmological constant problem.

    ↳ hep-thgr-qchep-phPRD(2016)·9 citations
43. 43*

    Analytical and Geometric approches of non-perturbative Quantum Field Theories

    Pierre J. Clavier🇫🇷

    We present the Hopf algebra of renormalization and introduce the renormalization group equation in this framework. Some linear Schwinger--Dyson equations are studied, and exact solutions are presented. Then we study the Schwinger--Dyson equation of the massless Wess--Zumino model in the physical plane and in the Borel plane. In the former the asymptotics of the solution of the Schwinger--Dyson equation is found and its perturbations are computed. In the later we study the singularities of the solution and their transcendental contents. The last chapter is a presentation of the BV formalism seen as theory of integration for the polyvector fields. The appendices contain a presentation of the geometric approach of the BRST formalism, an alternative description of the BV formalism that underlines the link between BRST and BV and some computations of Feynman integrals.

    ↳ math-phhep-phhep-thmath.MP1 citation
44. 44*

    Search for gamma-ray emission from eight dwarf spheroidal galaxy candidates discovered in Year Two of Dark Energy Survey with Fermi-LAT data

    Shang Li🇨🇳 · Yun-Feng Liang🇨🇳 · Kai-Kai Duan🇨🇳 · Zhao-Qiang Shen🇨🇳 · Xiaoyuan Huang🇩🇪 · Xiang Li🇨🇳 · Yi-Zhong Fan🇨🇳 · Neng-Hui Liao🇨🇳 · Lei Feng🇨🇳 · Jin Chang🇨🇳

    Very recently the Dark Energy Survey (DES) Collaboration has released their second group of Dwarf spheroidal (dSph) galaxy candidates. With the publicly-available Pass 8 data of Fermi-LAT we search for $\gamma -$ray emissions from the directions of these eight newly discovered dSph galaxy candidates. No statistically significant $\gamma -$ray signal has been found in the combined analysis of these sources. With the empirically estimated J-factors of these sources, the constraint on the annihilation channel of $\chi \chi \to {\tau }^{+}{\tau }^{-}$ is comparable to the bound set by the joint analysis of fifteen previously known dSphs with kinematically constrained J-factors for the dark matter mass $m_{\chi }>250$ GeV. In the direction of Tucana III (DES J2356-5935), one of the nearest dSph galaxy candidates that is $\sim 25$ kpc away, there is a weak $\gamma -$ray signal and its peak test statistic (TS) value for the dark matter annihilation channel $\chi \chi \to {\tau }^{+}{\tau }^{-1}$ is $\approx 6.7$ at $m_{\chi }\sim 15$ GeV. The significance of the possible signal likely increases with time. More data is highly needed to pin down the physical origin of such a GeV excess.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2016)·74 citations
45. 45*

    Mixed Inflaton and Spectator Field Models: CMB constraints and $\mu$ distortion

    Kari Enqvist🇫🇮 · Toyokazu Sekiguchi🇰🇷 · Tomo Takahashi🇯🇵

    We discuss mixed inflaton and spectator field models where both the fields are responsible for the observed density fluctuations. We use the current CMB data to constrain both the general mixed model as well as some specific representative scenarios, and collate the results with the model predictions for the CMB spectral $\mu$ distortion. We find the posterior distribution of $\mu$ using MCMC chains and demonstrate that the standard single-field inflaton model typically predicts $\mu \sim 10^{-8}$ with a relatively narrow distribution, whereas for the mixed models, the distribution turns out to be much broader, and $\mu$ could be larger by almost an order of magnitude. Hence future experiments of $\mu$ distortion could provide a tool for the critical testing of the mixed source models of the primordial perturbation.

    ↳ astro-ph.COhep-phJCAP(2016)·8 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.